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How blood group O protects against malaria

Posted in Hematology, Human Immune System in Health and in Disease on March 11, 2015| Leave a Comment »

How blood group O protects against malaria

Reporter: Aviva Lev-Ari, PhD, RN

Malaria is a serious disease that is estimated by the WHO to infect 200 million people a year, 600,000 of whom, primarily children under five, fatally. Malaria, which is most endemic in sub-Saharan Africa, is caused by different kinds of parasites from the plasmodium family, and effectively all cases of severe or fatal malaria come from the species known as Plasmodium falciparum. In severe cases of the disease, the infected red blood cells adhere excessively in the microvasculature and block the blood flow, causing oxygen deficiency and tissue damage that can lead to coma, brain damage and, eventually death. Scientists have therefore been keen to learn more about how this species of parasite makes the infected red blood cells so sticky.

It has long been known that people with blood type O are protected against severe malaria, while those with other types, such as A, often fall into a coma and die. Unpacking the mechanisms behind this has been one of the main goals of malaria research.

A team of scientists led from Karolinska Institutet in Sweden have now identified a new and important piece of the puzzle by describing the key part played by the RIFIN protein. Using data from different kinds of experiment on cell cultures and animals, they show how the Plasmodium falciparum parasite secretes RIFIN, and how the protein makes its way to the surface of the blood cell, where it acts like glue. The team also demonstrates how it bonds strongly with the surface of type A blood cells, but only weakly to type O.

Principal investigator Mats Wahlgren, a Professor at Karolinska Institutet’s Department of Microbiology, Tumour and Cell Biology, describes the finding as “conceptually simple”. However, since RIFIN is found in many different variants, it has taken the research team a lot of time to isolate exactly which variant is responsible for this mechanism.

“Our study ties together previous findings”, said Professor Wahlgren. “We can explain the mechanism behind the protection that blood group O provides against severe malaria, which can, in turn, explain why the blood type is so common in the areas where malaria is common. In Nigeria, for instance, more than half of the population belongs to blood group O, which protects against malaria.”

Source: www.eurekalert.org

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Acute Lung Injury

Posted in Biological Networks, Ca2+ triggered activation, Calcium Signaling, Calmodulin Kinase and Contraction, Cell Biology, Signaling & Cell Circuits, Chemical Biology and its relations to Metabolic Disease, Clinical Diagnostics, Curation, Cytoskeleton, Disease Biology, Disease Biology, Small Molecules in Development of Therapeutic Drugs, Drug Toxicity, Gene Regulation, Hematology, Human Immune System in Health and in Disease, Lipid metabolism, Metabolism, Metabolomics, Microbiology, Nitric Oxide in Health and Disease, Nutrition and Phytochemistry, Pharmaceutical Analytics, Pharmaceutical Drug Discovery, Pharmacologic toxicities, Plant extract, Proteins, Regulated Clinical Trials: Design, Methods, Components and IRB related issues, tagged Acute lung injury, cell supernatant, immunomodulation, lipopolysaccharide (LPS), plasma products, platelets, PPARs, Sepsis, transfusion reaction on February 26, 2015| Leave a Comment »

Acute Lung Injury

Writer and Curator: Larry H. Bernstein, MD, FCAP

Introduction

Acute lung injury is a serious phenomenon only recognized as having significant relevance to allogeneic blood transfusion in the last 15 years. It is not limited to transfusion events, and is also related to SIRS and sepsis. It is simulated in experimental models by lipoprotein, such as endotoxin. It occurs in the pretransfused surgical patient, or in the medical patient as well. Why it was not recognized earlier is a matter of conjecture. The significant reduction in immune modulated blood type incompatibility reactions in Western countries is a factor. The other factor is that the lipoprotein antigenic fractions involved are associated with component transfusions other than stored red cells. The following discussion will elaborate on what is increasingly recognized as a relevant issue in medicine today.
Transfusion Related Reaction

In medicine, transfusion related acute lung injury (TRALI) is a serious blood transfusion complication characterized by the acute onset of non-cardiogenic pulmonary edema following transfusion of blood products.^[1]

Although the incidence of TRALI has decreased with modified transfusion practices, it is still the leading cause of transfusion-related fatalities in the United States from fiscal year 2008 through fiscal year 2012.

Transfusion Related Acute Lung Injury

TRALI-Hyaline_membranes_-_very_high_mag

Micrograph of diffuse alveolar damage, the histologic correlate of TRALI. H&E stain. Very high magnification micrograph of hyaline membranes, as seen in diffuse alveolar damage (DAD), the histologic correlate of acute respiratory distress syndrome (ARDS), transfusion related acute lung injury (TRALI), acute interstitial pneumonia (AIP).
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Hyaline_membranes_-_very_high_mag.jpg/1024px-Hyaline_membranes_-_very_high_mag.jpg

TRALI is defined as an acute lung injury that is temporally related to a blood transfusion; specifically, it occurs within the first six hours following a transfusion.^[3]

It is typically associated with plasma components such as platelets and Fresh Frozen Plasma, though cases have been reported with packed red blood cells since there is some residual plasma in the packed cells. The blood component transfused is not part of the case definition. Transfusion-related acute lung injury (TRALI) is an uncommon syndrome that is due to the presence of leukocyte antibodies in transfused plasma. TRALI is believed to occur in approximately one in every 5000 transfusions. Leukoagglutination and pooling of granulocytes in the recipient’s lungs may occur, with release of the contents of leukocyte granules, and resulting injury to cellular membranes, endothelial surfaces, and potentially to lung parenchyma. In most cases leukoagglutination results in mild dyspnea and pulmonary infiltrates within about 6 hours of transfusion, and spontaneously resolves;

Occasionally more severe lung injury occurs as a result of this phenomenon and Acute Respiratory Distress Syndrome (ARDS) results. Leukocyte filters may prevent TRALI for those patients whose lung injury is due to leukoagglutination of the donor white blood cells, but because most TRALI is due to donor antibodies to leukocytes, filters are not helpful in TRALI prevention. Transfused plasma (from any component source) may also contain antibodies that cross-react with platelets in the recipient, producing usually mild forms of posttransfusion purpura or platelet aggregation after transfusion.

Another nonspecific form of immunologic transfusion complication is mild to moderate immunosuppression consequent to transfusion. This effect of transfusion is not completely understood, but appears to be more common with cellular transfusion and may result in both desirable and undesirable effects. Mild immunosuppression may benefit organ transplant recipients and patients with autoimmune diseases; however, neonates and other already immunosuppressed hosts may be more vulnerable to infection, and cancer patients may possibly have worse outcomes postoperatively.

http://en.wikipedia.org/wiki/Transfusion-related_acute_lung_injury

Perioperative transfusion-related acute lung injury: The Canadian Blood Services experience

Asim Alam, Mary Huang, Qi-Long Yi, Yulia Lin, Barbara Hannach
Transfusion and Apheresis Science 50 (2014) 392–398
http://dx.doi.org/10.1016/j.transci.2014.04.008

Purpose: Transfusion-related acute lung injury (TRALI) is a devastating transfusion-associated adverse event. There is a paucity of data on the incidence and characteristics of TRALI cases that occur perioperatively. We classified suspected perioperative TRALI cases reported to Canadian Blood Services between 2001 and 2012, and compared them to non-perioperative cases to elucidate factors that may be associated with an increased risk of developing TRALI in the perioperative setting. Methods: All suspected TRALI cases reported to Canadian Blood Services (CBS) since 2001 were reviewed by two experts or, from 2006 to 2012, the CBS TRALI Medical Review Group (TMRG). These cases were classified based on the Canadian Consensus Conference (CCC) definitions and detailed in a database. Two additional reviewers further categorized them as occurring within 72 h from the onset of surgery (perioperative) or not in that period (non-perioperative). Various demographic and characteristic variables of each case were collected and compared between groups. Results: Between 2001 and 2012, a total of 469 suspected TRALI cases were reported to Canadian Blood Services; 303 were determined to be within the TRALI diagnosis spectrum. Of those, 112 (38%) were identified as occurring during the perioperative period. Patients who underwent cardiac surgery requiring cardiopulmonary bypass (25.0%), general surgery (18.0%) and orthopedics patients (12.5%) represented the three largest surgical groups. Perioperative TRALI cases comprised more men (53.6% vs. 41.4%, p = 0.04) than non-perioperative patients. Perioperative TRALI patients more often required supplemental O2 (14.3% vs. 3.1%, p = 0.0003), mechanical ventilation (18.8% vs. 3.1%), or were in the ICU (14.3% vs. 3.7%, p = 0.0043) prior to the onset of TRALI compared to non-perioperative TRALI patients. The surgical patients were transfused on average more components than non-perioperative patients (6.0 [SD = 8.3] vs. 3.6 [5.2] products per patient, p = 0.0002). Perioperative TRALI patients were transfused more plasma (152 vs. 105, p = 0.013) and cryoprecipitate (51 vs. 23, p < 0.01) than non-perioperative TRALI patients. There was no difference between donor antibody test results between the groups. Conclusion: CBS data has provided insight into the nature of TRALI cases that occur perioperatively; this group represents a large proportion of TRALI cases.

Transfusion-related acute lung injury: a clinical review

Alexander P J Vlaar, Nicole P Juffermans
Lancet 2013; 382: 984–94
http://dx.doi.org/10.1016/S0140-6736(12)62197-7

Three decades ago, transfusion-related acute lung injury (TRALI) was considered a rare complication of transfusion medicine. Nowadays, the US Food and Drug Administration acknowledge the syndrome as the leading cause of transfusion-related mortality. Understanding of the pathogenesis of TRALI has resulted in the design of preventive strategies from a blood-bank perspective. A major breakthrough in efforts to reduce the incidence of TRALI has been to exclude female donors of products with high plasma volume, resulting in a decrease of roughly two-thirds in incidence. However, this strategy has not completely eradicated the complication. In the past few years, research has identified patient-related risk factors for the onset of TRALI, which have empowered physicians to take an individualized approach to patients who need transfusion.

Development of an international consensus definition has aided TRALI research, yielding a higher incidence in specific patient populations than previously acknowledged Patients suffering from a clinical disorder such as sepsis are increasingly recognized as being at risk for development of TRALI. Thereby, from a diagnosis by exclusion, TRALI has become the leading cause of transfusion-related mortality. However, the syndrome is still under diagnosed and under-reported in some countries.

Although blood transfusion can be life-saving, it can also be a life-threatening intervention. Physicians use blood transfusion on a daily basis. Increased awareness of the risks of this procedure is needed, because management of patient-tailored transfusion could reduce the risk of TRALI. Such an individualized approach is now possible as insight into TRALI risk factors evolves. Furthermore, proper reporting of TRALI could prevent recurrence.

Absence of an international definition for TRALI previously contributed to underdiagnosis. As such, a consensus panel, and the US National Heart, Lung and Blood Institute Working Group in 2004, formulated a case definition of TRALI based on clinical and radiological parameters. The definition is derived from the widely used definition of acute lung injury (panel 1). Suspected TRALI is defined as fulfilment of the definition of acute lung injury within 6 h of transfusion in the absence of another risk factor (panel 1).

Although this definition seems to be straightforward, the characteristics of TRALI are indistinguishable from acute lung injury due to other causes, such as sepsis or lung contusion. Therefore, this definition would rule out the possibility of diagnosing TRALI in a patient with an underlying risk factor for acute lung injury who has also received a transfusion. To identify such cases, the term possible TRALI was developed.

Although the TRALI definition is an international consensus definition, surveillance systems in some countries, including the USA, France and the Netherlands, use an alternative in which imputability is scored. Imputability aims to identify the likelihood that transfusion is the causal factor. Imputability scores mostly imply that other causes of acute lung injury can be ruled out, so that diagnosis of TRALI is by exclusion. However, observational and animal studies suggest that risk factors for TRALI include other disorders, such as sepsis. Therefore, an imputability definition would result in underdiagnosis of TRALI. The consensus definition accommodates the uncertainty of the association of acute lung injury to the transfusion in possible TRALI. The conventional definition of TRALI uses a timeframe of 6 h in which acute lung injury needs to develop after a blood transfusion. In critically ill patients, transfusion increases the risk (odds ratio 2·13, 95% CI 1·75–2·52) for development of acute lung injury 6–72 h after transfusion. However, whether the pathogenesis of delayed TRALI is similar to that of TRALI is unclear.

A two-hit hypothesis has been proposed for TRALI. The first hit is underlying patient factors, resulting in adherence of primed neutrophils to the pulmonary endothelium. The second hit is caused by mediators in the blood transfusion that activate the endothelial cells and pulmonary neutrophils, resulting in capillary leakage and subsequent pulmonary edema. The second hit can be antibody-mediated or non-antibody-mediated.

Panel 1: Definition of transfusion-related acute lung injury (TRALI)

Suspected TRALI

Acute onset within 6 h of blood transfusion
• PaO2/FIO2<300 mm Hg, or worsening of P to F ratio
• Bilateral infi ltrative changes on chest radiograph
• No sign of hydrostatic pulmonary oedema (pulmonary arterial occlusion
pressure ≤18 mm Hg or central venous pressure ≤15 mm Hg)
• No other risk factor for acute lung injury

Possible TRALI
Same as for suspected TRALI, but another risk factor present for acute lung injury

Delayed TRALI
Same as for (possible) TRALI and onset within 6–72 h of blood transfusion

Pathophysiology of two-hit mediated transfusion-related acute lung injury (TRALI). The pre-phase of the syndrome consists of a fi rst hit, which is mainly systemic. This first hit is the underlying disorder of the patient (eg, sepsis or pneumonia) causing neutrophil attraction to the capillary of the lung. Neutrophils are attracted to the lung by release of cytokines and chemokines from upregulated lung endothelium. Loose binding by L-selectin takes place. Firm adhesion is mediated by E-selectin and platelet-derived P-selectin and intracellular adhesion molecules (ICAM-1). In the acute phase of the syndrome, a second hit caused by mediators in the blood transfusion takes place. This hit results in activation of inflammation and coagulation in the pulmonary compartment. Neutrophils adhere to the injured capillary endothelium and marginate through the interstitium into the air space, which is filled with protein-rich edema fluid. In the air space, cytokines interleukin-1, -6, and -8, (IL-1, IL-6, and IL-8, respectively) are secreted, which act locally to stimulate chemotaxis and activate neutrophils resulting in formation of the elastase-α1-antitrypsin (EA) complex. Neutrophils can release oxidants, proteases, and other proinflammatory molecules, such as platelet-activating factor (PAF), and form neutrophil extracellular traps (NETs). Furthermore, activation of the coagulation system happens, shown by an increase in thrombin-antithrombin complexes (TATc), as does a decrease in activity of the fibrinolysis system, shown by a reduction in plasminogen activator activity. The influx of protein-rich edema fluid into the alveolus leads to the inactivation of surfactant, which contributes to the clinical picture of acute respiratory distress in the onset of TRALI. PAI-1 = plasminogen activator inhibitor-1.

Antibody-mediated TRALI is caused by passive transfusion of HLA or human neutrophil antigen (HNA) and corresponding antibodies from the donor directed against antigens of the recipient. Neutrophil activation occurs directly by binding of the antibody to the neutrophil surface (HNA antibodies) or indirectly, mainly by binding to the endothelial cells with activation of the neutrophil (HLA class I antibodies) or to monocytes with subsequent activation of the neutrophil (HLA class II antibodies). The antibody titer and the volume of antibody containing plasma both increase the risk for onset of TRALI. Although the role of donor HLA and HNA antibodies from transfused blood is widely accepted, not all TRALI cases are antibody mediated. In many patients, antibodies cannot be detected. Furthermore, many blood products containing antibodies do not lead to TRALI. This finding has led to development of an alternative hypothesis for the onset of TRALI, termed non-antibody-mediated TRALI.

Non-antibody-mediated TRALI is caused by accumulation of proinflammatory mediators during storage of blood products, and possibly by ageing of the erythrocytes and platelets themselves. Although most preclinical studies have noted a positive correlation between storage time of cell-containing blood products and TRALI, the mechanism is controversial. Two mechanisms have been suggested, including either plasma or the aged cells. In a small-case study and animal experiments, accumulation of bioactive lipids and soluble CD40 ligand (sCD40L) in the plasma layer of cell-containing blood products has been associated with TRALI. Bioactive lipids are thought to cause neutrophil activation through the G-protein coupled receptor on the neutrophil.

The two-hit model suggests that patients in a poor clinical state are at risk for development of TRALI. However, cases have been described of antibody-mediated TRALI developing in fairly healthy recipients. To explain this discrepancy, a threshold model has been suggested in which a threshold must be overcome to induce a TRALI reaction. The threshold is dependent both on the predisposition of the patient (first hit) and the quantity of antibodies in the transfusion (second hit). A large quantity of antibody that matches the recipient’s antigen can cause severe TRALI in a recipient with no predisposition.

Threshold model of antibody-mediated transfusion-related acute lung injury (TRALI). A specific threshold must be overcome to induce a TRALI reaction. To overcome a threshold, several factors act together: the activation status of the pulmonary neutrophils at the time of transfusion, the strength of the neutrophil-priming activity of transfused mediators (A), and the clinical status of the patient (B).

Panel 2: Clinical characteristics of transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO)

TRALI
• Dyspnea
• Fever
• Usually hypotension
• Hypoxia
• Leukopenia
• Thrombocytopenia
• Pulmonary edema on chest x-ray
• Normal left ventricular function*
• Normal pulmonary artery occlusion pressure

TACO
• Dyspnea
• Usually hypertension
• Hypoxia
• Pulmonary edema on chest radiographs
• Normal or decreased left ventricular function
• Increased pulmonary artery occlusion pressure
• Raised brain natriuretic peptide

Restrictive transfusion policy

The most effective prevention is a restrictive transfusion strategy. In a randomised clinical trial in critically ill patients, a restrictive transfusion policy for red blood cells was associated with a decrease in incidence of acute lung injury compared with a liberal strategy (7·7% vs 11·4%), suggesting that some of these patients might have had TRALI. The restrictive threshold was well tolerated and has greatly helped in guidance of red blood cell transfusion in the intensive-care unit.

Patient-tailored transfusion policy

Transfusion cannot be avoided altogether. A multivariate analysis in patients in intensive care showed that patient related risk factors contributed more to the onset of TRALI than did transfusion-related risk factors, suggesting that development of a TRALI reaction is dependent more on host factors then on factors in the blood product. Therefore, a patient-tailored approach aimed at reducing TRALI risk factors could be effective to alleviate the risk of TRALI.

Despite limitations of diagnostic tests, TRALI incidence seems to be high in at-risk patient populations. Therefore, TRALI is an underestimated health-care problem. Preventive measures, such as mainly male donor strategies, have been successful in reducing risk of TRALI. Identification of risk factors further improves the risk–benefit assessment of a blood transfusion. Efforts to further decrease the risk of TRALI needs increased awareness of this syndrome among physicians.

Transfusion-related acute lung injury: Current understanding and preventive strategies

A.P.J. Vlaar
Transfusion Clinique et Biologique 19 (2012) 117–124
http://dx.doi.org/10.1016/j.tracli.2012.03.001

Transfusion-related acute lung injury (TRALI) is the most serious complication of transfusion medicine. TRALI is defined as the onset of acute hypoxia within 6 hours of a blood transfusion in the absence of hydrostatic pulmonary edema. The past decades have resulted in a better understanding of the pathogenesis of this potentially life-threating syndrome. The present notion is that the onset of TRALI follows a threshold model in which both patient and transfusion factors are essential. The transfusion factors can be divided into immune and non-immune mediated TRALI. Immune-mediated TRALI is caused by the passive transfer of human neutrophil antibodies (HNA) or human leukocyte antibodies (HLA) present in the blood product reacting with a matching antigen in the recipient. Non-immune mediated TRALI is caused by the transfusion of stored cell-containing blood products. Although the mechanisms behind immune-mediated TRALI are reasonably well understood, this is not the case for non-immune mediated TRALI. The increased understanding of pathways involved in the onset of immune-mediated TRALI has led to the design of preventive strategies. Preventive strategies are aimed at reducing the risk to exposure of HLA and HNA to the recipient of the transfusion. These strategies include exclusion of “at risk” donors and pooling of high plasma volume products and have shown to reduce the TRALI incidence effectively.

Studies show that, in at risk patient populations, up to 8% of transfused patients may develop TRALI. Since the syndrome TRALI has been recognized, evidence on the pathogenesis of TRALI has been accumulating. The present notion is that the onset of TRALI follows a threshold model in which both patient and transfusion factors are essential in the development of TRALI. The transfusion factors can be divided into immune and non-immune mediated TRALI. Immune-mediated TRALI is caused by the passive transfer of human neutrophil antibodies (HNA) or human leukocyte antibodies (HLA) present in the blood product, reacting with a matching antigen in the recipient. Non-immune mediated TRALI is caused by the transfusion of stored cell-containing blood products. In recent years, many countries have successfully implemented preventive strategies resulting in a decrease of the incidence of TRALI.

Definition of transfusion-related acute lung injury (TRALI).

Acute onset within 6 hours after a blood transfusion
PaO2/FiO2 < 300 mmHg
Bilateral infiltrative changes on the chest X-ray
No sign of hydrostatic pulmonary edema (PAOP < 18 mmHg or CVP < 15 mmHg)
No other risk factor for acute lung injury present

Possible TRALI

Other risk factor for acute lung injury present

PAOP: pulmonary arterial occlusion pressure; CVP: central venous pressure

The first landmark report creating the basis for the understanding of the pathogenesis of TRALI was published by Popovsky et al. in 1983. They provided evidence on the association between the presence of leucocyte antibodies in the donor serum and onset of acute lung injury in the recipient of the transfusion. It was also recognized that multiparous blood donors whose plasma contained these antibodies represented a potential transfusion hazard. It was this research group that was the first to identify TRALI as a distinct clinical entity. Subsequently, many other authors reported on the association between the presence of HLA or HNA antibodies in donor blood and the onset of TRALI in the recipient.

Although the role of transfused blood donor HLA and HNA antibodies was widely accepted to be involved in the onset of TRALI, not all cases could be explained by this theory. A significant part of reported TRALI cases have no detectable antibodies. Also, many antibody-containing blood products fail to produce TRALI.

The alternative hypothesis proposed by the group of Silliman posed that TRALI is a “two hit” event. The “first hit” is the underlying condition of the patient, resulting in priming of the pulmonary neutrophil. The “second hit” is the transfusion of a blood product causing activation of the neutrophils in the pulmonary compartment, causing pulmonary edema finally resulting in TRALI. The transfusion factors causing the “second hit” are divided in two groups; immune and non-immune mediated TRALI.

The “second hit” is the transfusion itself and is either immune or non-immune mediated TRALI. The mechanisms behind immune-mediated TRALI are widely accepted and proven in both pre-clinical and clinical studies. The mechanisms involved in non-immune mediated TRALI are less clear.

The role of stored cell-containing blood products in the onset of non-immune TRALI has extensively been studied in preclinical and clinical studies. Although most of the pre-clinical studies find a positive correlation between the transfusion of stored cell-containing blood products in the presence of a “first hit” and the onset of TRALI, the mechanism behind the onset is controversial.

TRALI management consists mainly of preventing future adverse reactions and providing proper incidence estimates. All suspected TRALI cases should be reported to the blood bank for immunologic work-up as it is impossible to distinguish immune-mediated TRALI from non-immune mediated TRALI at bedside. Immunologic work-up includes testing of incompatibility by cross-matching donor plasma against recipient’s leucocytes. A donor with antibodies which are incompatible with the patient is excluded from further donation of blood for transfusion products. Furthermore, it is important to stress that the absence of a positive serologic work-up does not exclude the diagnosis of TRALI. TRALI is a clinical diagnosis and the immunologic work-up can be supportive but is not part of the diagnosis of TRALI. the two-event hypothesis and threshold hypothesis do not exclude the role of antibodies in the occurrence of TRALI in the presence of an inflammatory condition. Thus any patient fulfilling the TRALI definition (including possible TRALI) should be reported to the blood bank for an immunologic work-up of the recipient and the implicated donors on the presence of HLA and HNA antibodies.

Prevention of immune-mediated TRALI is achieved by exclusion of donors proven to have HLA or HNA antibodies in their plasma present or donors “at risk” to have these antibodies present.

Exclusion of HLA or HNA positive donors
Exclusion of donors “at risk” of being HLA or HNA positive
Female donors – more specifically, multiparous donors
Testing donors for HLA or HNA antibodies
Multiple plasma pooling
solvent/detergent plasma is produced from multiple donations, leading to an at least 500-fold dilution of a single plasma unit;
neither HNA nor HLA antibodies are detectable in solvent/detergent fresh frozen plasma.
To prevent non-immune mediated TRALI, the use of fresh blood only has been suggested

Strategies to prevent the onset of TRALI include the exclusion of female plasma donors and the pooling of plasma products. These strategies have already been implemented in some countries resulting in a reduction of the incidence of TRALI.
Transfusion-related immunomodulation (TRIM): An update

Eleftherios C. Vamvakas, Morris A. Blajchman
Blood Reviews (2007) 21, 327–348
http://dx.doi.org:/10.1016/j.blre.2007.07.003

Allogeneic blood transfusion (ABT)-related immunomodulation (TRIM) encompasses the laboratory immune aberrations that occur after ABT and their established or purported clinical effects. TRIM is a real biologic phenomenon resulting in at least one established beneficial clinical effect in humans, but the existence of deleterious clinical TRIM effects has not yet been confirmed. Initially, TRIM encompassed effects attributable to ABT by immunomodulatory mechanisms (e.g., cancer recurrence, postoperative infection, or virus activation). More recently, TRIM has also included effects attributable to ABT by pro-inflammatory mechanisms (e.g., multiple-organ failure or mortality). TRIM effects may be mediated by: (1) allogeneic mononuclear cells; (2) white-blood-cell (WBC)-derived soluble mediators; and/or (3) soluble HLA peptides circulating in allogeneic plasma. This review categorizes the available randomized controlled trials based on the inference(s) that they permit about possible mediator(s) of TRIM, and examines the strength of the evidence available for relying on WBC reduction or autologous transfusion to prevent TRIM effects.

Allogeneic blood transfusion (ABT) may either cause alloimmunization or induce tolerance in recipients. ABTs introduce a multitude of foreign antigens into the recipient, including HLA-DR antigens found on the donor’s dendritic antigen presenting cells (APCs). The presence or absence of recipient HLA-DR antigens on the donor’s white blood cells (WBCs) plays a decisive role as to whether alloimmunization or immune suppression will ensue following ABT. In general, allogeneic transfusions sharing at least one HLA-DR antigen with the recipient induce tolerance, while fully HLA-DR-mismatched transfusions lead to alloimmunization.

In addition to the degree of HLA-DR compatibility between donor and recipient, the immunogenicity of cellular or soluble HLA antigens associated with transfused blood components depends on the viability of the donor dendritic APCs and the presence of co-stimulatory signals for the presentation of the donor antigens to the recipient’s T cells. Nonviable APCs and/or the absence of the requisite co-stimulatory signals result in T-cell unreponsiveness. Thus, when a multitude of antigens is introduced into the host by an ABT, the host response to some of these antigens is often decreased, and immune tolerance ensues. ABT has been shown to cause decreased helper T-cell count, decreased helper/suppressor T-lymphocyte ratio, decreased lymphocyte response to mitogens, decreased natural killer (NK) cell function, reduction in delayed-type hypersensitivity, defective antigen presentation, suppression of lymphocyte blastogenesis, decreased cytokine (IL-2, interferon-c) production, decreased monocyte/macrophage phagocytic function, and increased production of antiidiotypic and anticlonotypic antibodies.

All these laboratory immune aberrations that indicate immune suppression and occur in transfused patients could potentially be associated with clinically-manifest ABT effects. Thus a variety of beneficial or deleterious clinical effects, potentially attributable to ABT-related immunosuppression, have been described over the last 30 years. The constellation of all such ABT-associated laboratory and clinical findings is known as ABT-related immunomodulation (TRIM). Initially, TRIM encompassed effects attributable to ABT by means of immunologic mechanisms only; however more recently, the term has been used more broadly, to encompass additional effects that could be related to ABT by means of ‘‘proinflammatory’’ rather than ‘‘immunomodulatory’’ mechanisms.

Over 30 years ago, it was reported that pre-transplant ABTs could improve renal-allograft survival in patients who had undergone renal transplantation. This beneficial immunosuppressive effect of ABT has been confirmed by animal data, observational clinical studies, and clinical experience worldwide, although it has not been proven in randomized controlled trials (RCTs). Before the advent of the AIDS pandemic, it had become standard policy in many renal units to deliberately expose patients on transplant waiting lists to one or more red blood cell (RBC) transfusions.

All the available data considered together indicate that TRIM is most likely a real biologic phenomenon, which results in at least one established beneficial clinical effect in humans, although the available evidence has not yet confirmed the existence and/or magnitude of the deleterious clinical TRIM effects. In fact, the debate over the existence of such deleterious clinical TRIM effects has been long and sometimes acrimonious.

Many studies tended to indicate that patients receiving perioperative transfusion (compared with those not needing transfusion) almost always had a higher risk of developing postoperative bacterial infection. The studies also indicated that patients receiving ABT differed from those not receiving a transfusion in several prognostic factors that predisposed to adverse clinical outcomes.

The specific constituent(s) of allogeneic blood that mediate(s) either or both the immunomodulatory and the pro-inflammatory effect(s) of ABT remain
(s) unknown, and the published literature suggests that these TRIM effects
may be mediated by: (1) allogeneic mononuclear cells; (2) soluble biologic response modifiers released in a time dependent manner from WBC granules or membranes into the supernatant fluid of RBC or platelet concentrates
during storage; and/or (3) soluble HLA class I peptides that circulate in allogeneic plasma. If each of these mediators do cause TRIM effects, ABT effects mediated by allogeneic mononuclear cells would be expected to be preventable by WBC reduction (performed either before or after storage of cellular blood components), as well as by autologous transfusion. The ABT effects mediated by soluble HLA peptides circulating in allogeneic plasma would be expected to be preventable only by autologous transfusion.

BENEFICIAL TRIM EFFECTS

Enhanced survival of renal allografts
Reduced recurrence rate of Crohn’s disease

DELETERIOUS

Increased recurrence rate of resected malignancies
Increased incidence of postoperative bacterial infections
Activation of endogenous CMV or HIV infection
Increased short-term (up to 3-month) mortality

Possible mechanisms and mediators of TRIM effects

Although the mechanisms of TRIM have been debated extensively, the exact mechanism(s) of this phenomenon has yet to be elucidated. A number of putative mechanisms have been postulated. The three major mechanisms accounting for much of the experimental data include:

clonal deletion,
induction of anergy, and
immune suppression.

Conceptually, clonal deletion refers to the inactivation and removal of alloreactive lymphocytes that would, for example, cause the rejection of an allograft; anergy implies immunologic nonresponsiveness; and immune suppression suggests that the responding cell is being inhibited of doing so by a cellular mechanism or by a cytokine. Antiidiotypic antibodies, which are predominantly of the V_H6 gene family, have also been demonstrated in the sera of ABT recipients and in patients with long-term functioning renal allografts.

To date, no RCT has enrolled patients with sarcomas—tumors whose growth is stimulated by TGF-β—or patients with tumors for which the immune response plays a major role. (These would include skin tumors—such as melanomas, keratoacanthomas, squamous and basal-cell carcinomas—and certain virus-induced tumors—notably Kaposi’s sarcoma and certain lymphomas.) Instead, the 3 available RCTs of ABT and cancer recurrence enrolled patients with colorectal cancer—a tumor that is not sufficiently antigenic to render an impairment of host immunity capable of facilitating tumor growth, and a tumor whose cells have not been shown to be stimulated by TGF-β.

Fig not shown. Randomized controlled trials (RCTs) investigating the association of WBC-containing allogeneic blood transfusion (ABT) with cancer recurrence. For each RCT, the figure shows the odds ratio (OR) of cancer recurrence in recipients of non-WBC-reduced allogeneic versus autologous or WBC-reduced allogeneic RBCs, as calculated from an intention-to-treat analysis. A deleterious effect of ABT (and thus a benefit from autologous transfusion or WBC reduction) exists when the OR is greater than 1 as well as statistically significant. (In the figure, each OR is surrounded by its 95% confidence interval [CI]; if the 95% CI of the OR includes the null value of 1, the TRIM effect is not statistically significant [p > 0.05]).

Fig not shown. Randomized controlled trials (RCTs) investigating the association of WBC-containing allogeneic blood transfusions with postoperative infection (n = 17). For each RCT, the figure shows the odds ratio (OR) of postoperative infection in recipients of non-WBC reduced allogeneic versus autologous or WBC-reduced allogeneic RBCs, as calculated from an intention-to-treat analysis. A deleterious effect of ABT (and thus a benefit from autologous transfusion or WBC reduction) exists when the OR is greater than 1 as well as statistically significant. (In the figure, each OR is surrounded by its 95% confidence interval [CI]; if the 95% CI of the OR includes the null value of 1, the TRIM effect is not statistically significant [p > 0.05]).

The totality of the evidence from RCTs does not demonstrate a TRIM effect manifest across all clinical settings and transfused RBC products. Instead, WBC-containing ABT is associated with an increased risk of short-term (up to 3-month post transfusion) mortality from all causes combined specifically in cardiac surgery. The additional deleterious TRIM effect detected by the latest meta-analysis (i.e., the effect on postoperative infection prevented by poststorage filtration) contradicts current theories about the pathogenesis of TRIM, because it is not accompanied by a similar or larger effect prevented by prestorage filtration.

Thus, only in cardiac surgery (Fig. 5 – not shown) are the findings of RCTs pertaining to a deleterious TRIM effect consistent. Even in this setting, however, the reasons for the excess deaths attributed to WBC containing ABT remain elusive. The initial hypothesis suggested that WBC-containing ABT may predispose to MOF which, in turn, may predispose to mortality. However, hitherto, no cardiac-surgery RCT has demonstrated an association between WBC-containing ABT and MOF, and no other cause of death specifically attributed to WBC-containing ABT has been proposed.

The TRIM effect seen in cardiac surgery deserves further study to pinpoint the cause(s) of the excess deaths, but-now that the majority of transfusions in Western Europe and North America are WBC reduced- the undertaking of further RCTs comparing recipients of non-WBC-reduced versus WBC reduced allogeneic RBCs in cardiac surgery is unlikely. For countries that have not yet converted to universal WBC reduction, whether to opt for WBC reduction of all cellular blood components transfused in cardiac surgery-in the absence of information on the specific cause(s) of death ascribed to WBC-containing ABT-is a policy decision that will have to be made based on the hitherto available data.

Regulation of alveolar fluid clearance and ENaC expression in lung by exogenous angiotensin II

Jia Denga, Dao-xin Wanga, Wang Deng, Chang-yi Li, Jin Tong, Hilary Ma
Respiratory Physiology & Neurobiology 181 (2012) 53– 61
http://dx.doi.org:/10.1016/j.resp.2011.11.009

Angiotensin II (Ang II) has been demonstrated as a pro-inflammatory effect in acute lung injury, but studies of the effect of Ang II on the formation of pulmonary edema and alveolar filling remains unclear. Therefore, in this study the regulation of alveolar fluid clearance (AFC) and the expression of epithelial sodium channel (ENaC) by exogenous Ang II was verified. SD rats were anesthetized and were given Ang II with increasing doses (1, 10 and 100 [1]g/kg per min) via osmotic minipumps, whereas control rats received only saline vehicle. AT1 receptor antagonist ZD7155 (10 mg/kg) and inhibitor of cAMP degeneration rolipram (1 mg/kg) were injected intraperitoneally 30 min before administration of Ang II. The lungs were isolated for measurement of alveolar fluid clearance. The mRNA and protein expression of ENaC were detected by RT-PCR and Western blot. Exposure to higher doses of Ang II reduced AFC in a dose-dependent manner and resulted in a non-coordinate regulation of α-ENaC vs the regulation of β- and ϒ-ENaC, however Ang II type 1 (AT1) receptor antagonist ZD7155 prevented the Ang II-induced inhibition of fluid clearance and dysregulation of ENaC expression. In addition, exposure to inhibitor of cAMP degradation rolipram blunted the Ang II-induced inhibition of fluid clearance. These results indicate that through activation of AT1 receptor, exogenous Ang II promotes pulmonary edema and alveolar filling by inhibition of alveolar fluid clearance via downregulation of cAMP level and dysregulation of ENaC expression.

Effects of angiotensin II (Ang II) receptor antagonists and rolipram on AFC

Effects of angiotensin II (Ang II) receptor antagonists and rolipram on rat alveolar fluid clearance (AFC). Then AFC was measured 1 h after fluid instillation (4 mL/kg). Amiloride (100 [1]M), Ang II (10−7 M), ZD7155 (10−6 M), and rolipram (10−5 M) were added to the instillate as indicated (n = 10 per group). Mean values ± SEM. p < 0.01 vs control. p < 0.01 vs Ang II + ZD7155.
p < 0.05 vs amiloride. p < 0.05 vs Ang II.

Effects of angiotensin II (Ang II) on cyclic adenosine monophosphate (cAMP)

Effects of angiotensin II (Ang II) on cyclic adenosine monophosphate (cAMP) concentration in lung. Rats were given saline or Ang II (1, 10 and 100 µg/kg per min) for 6 h, and cAMP in lung was determined by RIA (n = 30 per group). Mean values ± SEM. p < 0.01 vs control. p < 0.05 vs 10 µg/kg Ang II.

Histological examination of lung

Histological examination of lung. Rats were given saline or Ang II (10 µg/kg per min) by osmotic minipump for 6 h. ZD7155 (10 mg/kg) was injected intraperitoneally 30 min before administration of Ang II. Shown are representative lung specimens obtained from the control (A), Ang II (B) and Ang II + ZD7155 (C) groups. All photographs are at 100× magnification. Interstitial edema and inflammatory cell infiltration were seen in Ang II group, but reduced in Ang II + ZD7155 group.
The present results demonstrate that Ang II infusion is associated with pulmonary edema and alveolar filling. Three important findings were observed:

(1) high doses of Ang II led to reduction of alveolar fluid clearance, and this effect was blunted by an AT1 receptor antagonist.
(2) Ang II infusion increased the abundance of α-ENaC, whereas decreased the abundance ofβ and ϒ-ENaC, and these effects were reversed in response to an AT1 receptor antagonist.
(3) Ang II infusion decreased cAMP concentration in lung tissue, and an inhibitor of cAMP degradation prevented inhibition of alveolar fluid clearance by Ang II, but had no effect on the dysregulation of ENaC.

Our data indicate that Ang II results in pulmonary edema by inhibition of alveolar fluid clearance via down-regulation of cellular cAMP level and dysregulation of the abundance of ENaC, whereas these effects are prevented by an AT1 receptor antagonist.

The renin-angiotensin system is a major regulator of body fluid and sodium balance, predominantly through the actions of its main effector Ang II. Several previous experimental studies demonstrated that plasma Ang II levels vary in both physiological and pathological conditions. In the kidney, Ang II added to the peritubular perfusion has a biphasic action with stimulation of sodium reabsorption at low doses (10−12–10−10M) and inhibition at high doses (10−7–10−6M) (Harris and Young, 1977). In vitro, Ang II also exerts a dose-dependent dual action on intestinal absorption (Levens, 1985). The evidence shows that the effect of Ang II on sodium and water absorption is dose-dependent. Our results showed that low intravenous doses of Ang II (<1 µg/kg per min) had no effect on alveolar fluid clearance which represents the sodium and water reabsorption in alveoli. However, with high intravenous doses, Ang II decreased alveolar fluid clearance. This finding suggests that the effect of Ang II on fluid absorption in lung is also dose-dependent.

Rat models of acute lung injury: Exhaled nitric oxide as a sensitive,noninvasive real-time biomarker of prognosis and efficacy of intervention

Fangfang Liu, Wenli Lib, Jürgen Pauluhn, Hubert Trübel, Chen Wang
Toxicology 310 (2013) 104– 114
http://dx.doi.org/10.1016/j.tox.2013.05.016

Exhaled nitric oxide (eNO) has received increased attention in clinical settings because this technique is easy to use with instant readout. However, despite the simplicity of eNO in humans, this endpoint has not frequently been used in experimental rat models of septic (endotoxemia) or irritant acute lung injury (ALI). The focus of this study is to adapt this method to rats for studying ALI-related lung disease and whether it can serve as instant, non-invasive biomarker of ALI to study lung toxicity and pharmacological efficacy. Measurements were made in a dynamic flow of sheath air containing the exhaled breath from spontaneously breathing, conscious rats placed into a head-out volume plethysmograph. The quantity of eNO in exhaled breath was adjusted (normalized) to the physiological variables (breathing frequency, concentration of exhaled carbon dioxide) mirroring pulmonary perfusion and ventilation. eNO was examined on the instillation/inhalation exposure day and first post-exposure day in Wistar rats intratracheally instilled with lipopolysaccharide (LPS) or single inhalation exposure to chlorine or phosgene gas. eNO was also examined in a Brown Norway rat asthma model using the asthmagen toluene diisocyanate (TDI). The diagnostic sensitivity of adjusted eNO was superior to the measurements not accounting forthe normalization of physiological variables. In all bioassays – whether septic, airway or alveolar irritant or allergic, the adjusted eNO was significantly increased when compared to the concurrent control. The maximum increase of the adjusted eNO occurred following exposure to the airway irritant chlorine. The specificity of adjustment was experimentally verified by decreased eNO following inhalation dosing ofthe non-selective nitric oxide synthase inhibitor amoni-guanidine. In summary, the diagnostic sensitivity of eNO can readily be applied to spontaneously breathing, conscious rats without any intervention or anesthesia. Measurements are definitely improved by accounting for the disease-related changes inexhaled CO2and breathing frequency. Accordingly, adjusted eNO appears to be a promising methodological improvement for utilizing eNO in inhalation toxicology and pharmacological disease models
with fewer animals.

Role of p38 MAP Kinase in the Development of Acute Lung Injury

J Arcaroli, Ho-Kee Yum, J Kupfner, JS Park, Kuang-Yao Yang, and E Abraham
Clinical Immunology 2001; 101(2):211–219
http://dx.doi.org:/10.1006/clim.2001.5108

Acute lung injury (ALI) is characterized by an intense pulmonary inflammatory response, in which neutrophils play a central role. The p38 mitogen-activated protein kinase pathway is involved in the regulation of stress-induced cellular functions and appears to be important in modulating neutrophil activation, particularly in response to endotoxin. Although p38 has potent effects on neutrophil functions under in vitro conditions, there is relatively little information concerning the role of p38 in affecting neutrophil driven inflammatory responses in vivo. To examine this issue, we treated mice with the p38 inhibitor SB203580 and then examined parameters of neutrophil activation and acute lung injury after hemorrhage or endotoxemia. Although p38 was activated in lung neutrophils after hemorrhage or endotoxemia, inhibition of p38 did not decrease neutrophil accumulation in the lungs or the development of lung edema under these conditions. Similarly, the increased production of proinflammatory cytokines and activation of NF-kB in lung neutrophils induced by hemorrhage or endotoxemia was not diminished by p38 inhibition. These results indicate that p38 does not have a central role
in the development of ALI after either hemorrhage or endotoxemia.

The coagulation system and pulmonary endothelial function in acute lung injury

James H. Finigan
Microvascular Research 77 (2009) 35–38
http://dx.doi.org:/10.1016/j.mvr.2008.09.002

Acute lung injury (ALI) is a disease marked by diffuse endothelial injury and increased capillary permeability. The coagulation system is a major participant in ALI and activation of coagulation is both a consequence and contributor to ongoing lung injury. Increased coagulation and depressed fibrinolysis result in diffuse alveolar fibrin deposition which serves to amplify pulmonary inflammation. In addition, existing evidence demonstrates a direct role for different components of coagulation on vascular endothelial barrier function. In particular, the pro-coagulant protein thrombin disrupts the endothelial actin cytoskeleton resulting in increased endothelial leak. In contrast, the anti-coagulant activated protein C (APC) confers a barrier protective actin configuration and enhances the vascular barrier in vitro and in vivo. However, recent studies suggest a complex landscape with receptor cross-talk, temporal heterogeneity and pro-coagulant/anticoagulant protein interactions. In this article, the major signaling pathways governing endothelial permeability in lung injury are reviewed with a particular focus on the role that endothelial proteins, such as thrombin and APC, which play on the vascular barrier function.

Acute lung injury (ALI) is a devastating illness with an annual incidence of approximately 200,000 and a mortality of 40%. Most commonly seen in the setting of sepsis, ALI is a complex inflammatory syndrome marked by increased vascular permeability resulting in tissue edema and organ dysfunction. The vascular endothelium is a key target and critical participant in the pathogenesis of sepsis-induced organ dysfunction and disruption of the endothelial barrier is central to the pathophysiology of both sepsis and ALI. Sepsis and acute lung injury (ALI) are syndromes marked by diffuse inflammation with a key feature being endothelial cell barrier disruption and increased vascular permeability resulting in widespread organ dysfunction. The endothelial cytoskeleton has been identified as a critical regulator of vascular barrier integrity with a current model of endothelial barrier regulation suggesting a balance between barrier-disrupting cellular contractile forces and barrier-protective cell–cell and cell–matrix forces. These competing forces exert their opposing effects via manipulation of the actin-based endothelial cytoskeleton and associated endothelial regulatory proteins. Endothelial cells generate tension via an actomyosin motor, and focally distributed changes in tension/relaxation can be accomplished by spatially-defined regulation of the phosphorylation of the regulatory 20 kDa myosin light chain (MLC) catalyzed by the Ca2+/calmodulin (CaM)-dependent enzyme myosin light chain kinase (MLCK).

Thrombin is the proto-typical coagulation protein with direct effects on the endothelial barrier via alterations in the cytoskeleton. In the coagulation cascade, thrombin converts fibrinogen to fibrin in the final step of thrombus formation and also activated platelets. In addition, this multifunctional protease is present at sites of vascular inflammation and induces barrier dysfunction. Through its receptor, protease-activated receptor-1 (PAR1), thrombin initiates a series of events which includes MLC phosphorylation, dramatic cytoskeletal reorganization and stress fiber formation, increased cellular contractility, paracellular gap formation, and enhanced fluid and protein transport. Similarly, thrombin exposure results in increased pulmonary edema in vivo, a finding which is also seen after treatment with a PAR1 activating peptide and attenuated in PAR1 knockout mice.

Disruptions in the coagulation system have long been recognized to be an integral part of inflammation, sepsis and ALI. In 1969, Saldeen demonstrated that thrombin infusion produced canine respiratory insufficiency which was linked pathologically to emboli in the pulmonary microcirculation, a condition he labeled the “Microembolism Syndrome” (Saldeen, 1979). Elemental to the pathophysiology of sepsis and ALI is a shift towards a pro-coagulant state. Bronchoalveolar (BAL) fluid from patients with ALI reflects this increase in procoagulant activity with elevated levels of fibrinopeptide A, factor VII and d-dimer. Concomitantly, there is a decrease in fibrinolytic activity, as shown by depressed BAL levels of urokinase and increased levels of the fibrinolysis inhibitors plasminogen activator inhibitor (PAI) and α2-antiplasmin.

Given that APC is a vascular endothelial protein which interacts with other coagulation proteins such as thrombin, it seems logical that it might have an effect on endothelial integrity. In cultured human pulmonary endothelial cells, while thrombin results in decreased electrical resistance, a reflection of increased permeability, pre- or post-exposure to physiologic concentrations of APC significantly attenuates this thrombin-induced drop in resistance. These APC-mediated alterations in barrier function are associated with MLC phosphorylation as well as activation of the endothelial protein Rac, and cytoskeletal re-arrangement in a barrier protective configuration all findings very reminiscent of the barrier protective signaling induced by the bioactive lipid, S1P. Interestingly, APC appears to activate sphingosine kinase and mediate its barrier protective effects through PI3 kinase and AKT-dependent ligation of the S1P receptor, S1P1. Moreover, the endothelial barrier-protective effects of APC have been observed in other tissues including brain and kidney. The barrier protection in these beds appears independent of any anti-coagulant effect of APC and is associated with decreased endothelial apoptosis.

Recently, the endothelial protein C receptor (EPCR) has been identified as a crucial participant in the protein C pathway. Structurally similar to the major histocompatibility class I/CD1 family of molecules, EPCR binds protein C, presenting it to the thrombin/TM complex, thereby increasing the activation of protein C by ∼20 fold. Importantly, APC can also bind EPCR, and while the bound form of APC loses its extra-cellular anti-coagulant activity, increasing evidence indicates that much, if not all, of APC intra-cellular signaling requires EPCR. APC-mediated increases in endothelial phosphor-MLC and activated Rac are all EPCR-dependent and APC-induced endothelial barrier protection requires ligation of EPCR.

Sepsis and ALI are significant causes of morbidity and mortality in the intensive care unit and are marked by zealous activation of the coagulation system. While this could conceivably confer certain benefits, such as enclosing and spatially controlling an infection, it is clear that this pro-coagulant environment participates in the pathophysiology of ALI, particularly via exacerbating endothelial damage and augmenting endothelial permeability. However, the biology of coagulation in ALI is incompletely understood and trials of new therapies specifically targeting coagulation in patients with ALI have been disappointing. Despite this, recent advances in the knowledge of the dynamic interplay between inflammation and coagulation in ALI as well as endothelial receptor-ligand binding and receptor cross talk have stimulated promising research and identified novel therapeutic targets for patients with ALI.

Phosphatidylserine-expressing cell by-products in transfusion: A pro-inflammatory or an anti-inflammatory effect?

Saas, F. Angelot, L. Bardiaux, E. Seilles, F. Garnache-Ottou, S. Perruche
Transfusion Clinique et Biologique 19 (2012) 90–97
http://dx.doi.org/10.1016/j.tracli.2012.02.002

Labile blood products contain phosphatidylserine-expressing cell dusts, including apoptotic cells and microparticles. These cell by-products are produced during blood product process or storage and derived from the cells of interest that exert a therapeutic effect (red blood cells or platelets). Alternatively, phosphatidylserine-expressing cell dusts may also derived from contaminating cells, such as leukocytes, or may be already present in plasma, such as platelet-derived microparticles. These cell by-products present in labile blood products can be responsible for transfusion induced immunomodulation leading to either transfusion-related acute lung injury (TRALI) or increased occurrence of post-transfusion infections or cancer relapse. In this review, we report data from the literature and our laboratory dealing with interactions between antigen-presenting cells and phosphatidylserine-expressing cell dusts, including apoptotic leukocytes and blood cell-derived microparticles. Then, we discuss how these phosphatidylserine-expressing cell by-products may influence transfusion.

Potential consequences of phosphatidylserine-expressing cell by-products in transfusion

Potential consequences of phosphatidylserine-expressing cell by-products in transfusion. Interactions of phosphatidylserine-expressing cell dusts (apoptotic cells or microparticles) may lead to antigen-presenting cell activation or inhibition. Antigen-presenting cell activation may trigger inflammation and be involved in transfusion-related acute lung injury (TRALI), while antigen-presenting cell inhibition may exert transient immunosuppression or tolerance. Blood product process or storage may influence the generation of phosphatidylserine-expressing cell dusts. PtdSer: phosphatidylserine; APC: antigen-presenting cell.

Several publications report the presence of phosphatidylserine-expressing cell by-products in blood products. These cell by-products may be generated during the blood product process, such as filtration, or during storage (either cold storage for red blood cells or between 20–24 ◦C for platelets). Alternatively, they may be limited by filtration. Phosphatidylserine-expressing cell by-products can be apoptotic cells. Apoptotic cells have been found in different blood products: red blood cell units and platelet concentrates. These apoptotic cells correspond to dying cells of interest: red blood cells or platelets, both enucleated cells that can undergo apoptosis.

Immunomodulatory effects of apoptotic leukocytes

Immunomodulatory effects of apoptotic leukocytes. Early during the apoptotic program, phosphatidylserine-exposure occurs leading to apoptotic cell removal by macrophages or conventional dendritic cells. This uptake by antigen-presenting cells induces the production of anti-inflammatory factors and concomitantly inhibits the synthesis of inflammatory cytokines. These antigen-presenting cells are refractory to TLR activation. This leads to a transient immunosuppressive microenvironment. If antigen-presenting cells from this microenvironment migrate to secondary lymphoid organs, naive T cells are converted into inducible regulatory T cells. This leads to tolerance against apoptotic cell-derived antigens. M[1]: macrophage; cDC: conventional dendritic cells; PtdSer: phosphatidylserine; Treg: regulatory T cells; Th1: helper T cells; HGF: hepatocyte growth factor; IL-: interleukin; NO: nitrite oxide; PGE-2: prostaglandin-E2; TGF: transforming growth factor; TNF: tumor necrosis factor; TLR: Toll-like receptor.

Implication of phosphatidylserine in the inhibition of both inflammation and specific immune responses has been further demonstrated using phosphatidylserine-expressing liposomes and is sustained by the following observations:

phosphatidylserine-dependent ingestion of apoptotic cells induces TGF-β secretion and resolution of lung inflammation;
inhibition of phosphatidylserine recognition through annexin-V enhances the immunogenicity of irradiated tumor cells in vivo;
masking of phosphatidylserine inhibits apoptotic cell engulfment and induces autoantibody production in mice.

Based on data from our group and Peter Henson’s group, some authors have speculated that apoptotic leukocytes present in blood products may be responsible for transfusion-related immunosuppression.

The first consequences of phosphatidylserine-expressing apoptotic cells in blood products may be a transient immunosuppression−responsible for an increase in infection rate and of cancer relapse−or tolerance induction− as observed after donor-specific transfusion − when Treg have been generated. However, apoptotic leukocytes become secondarily necrotic in the absence of phagocytes. This may certainly occur in blood product bags. Necrotic cells, through the release of damage-associated molecular patterns, may become immunogenic. The same process may occur for platelets. Necrotic platelets may represent the procoagulant form of platelets. Thus, hemostatic activation of platelets or their by-products may link thrombosis and inflammation to amplify lung microvascular damage during nonimmune TRALI.

What are the next steps to answer the question on the role of phosphatidylserine-expressing cell dusts in the modulation of immune responses after transfusion?

The next steps are to characterize or identify factors involved in the triggering of inflammation or its inhibition and produced during blood product storage or process. Several factors influence the immune responses against dying cells. We can speculate on some factors, including:

the number of phosphatidylserine-expressing cell byproducts contained per blood product, as the immunogenicity of apoptotic cells may be proportional to their number;
the occurrence of secondary necrosis and so the passive release of intracellular damage-associated molecular patterns that overpasses the inhibitory signals delivered by phosphatidylserine. One of these damage associated molecular patterns can be the heme released from stored red blood cells which signals via TLR4;
the size of cell by-products and especially microparticles, since these latter exert different functions according to their size. Moreover, antigen-presenting cells, such as plasmacytoid dendritic cells, respond only to lower size synthetic particles. This may explain the different responses observed between “amateur” phagocytes (plasmacytoid dendritic cells) versus professional phagocytes (conventional dendritic cells/macrophages) after incubation with microparticles. The size of cell by-products diminishes during plasma filtration, as assessed by dynamic light scattering from 101 to 464 nm in unfiltered fresh-frozen plasma versus 21 to 182 nm after 0.2 µm filtration process;
expression of the recently described phosphatidylserine receptors on different antigen-presenting cell subsets may also explain the different responses between plasmacytoid dendritic cells versus conventional dendritic cells/macrophages and may impact on the overall immune response.

Peroxisome proliferator-activated receptors and inflammation

Leonardo A. Moraes, Laura Piqueras, David Bishop-Bailey
Pharmacology & Therapeutics 110 (2006) 371 – 385
http://dx.doi.org:/10.1016/j.pharmthera.2005.08.007

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptors family. PPARs are a family of 3 ligand-activated transcription factors: PPARa (NR1C1), PPARh/y (NUC1; NR1C2), and PPARg (NR1C3). PPARα, -h/y, and -ϒ are encoded by different genes but show substantial amino acid similarity, especially within the DNA and ligand binding domains. All PPARs act as heterodimers with the 9-cis-retinoic acid receptors (retinoid X receptor; RXRs) and play important roles in the regulation of metabolic pathways, including those of lipid of biosynthesis and glucose metabolism, as well as in a variety of cell differentiation, proliferation, and apoptosis pathways. Recently, there has been a great deal of interest in the involvement of PPARs in inflammatory processes. PPAR ligands, in particular those of PPARα and PPARϒ, inhibit the activation of inflammatory gene expression and can negatively interfere with proinflammatory transcription factor signaling pathways in vascular and inflammatory cells. Furthermore, PPAR levels are differentially regulated in a variety of inflammatory disorders in man, where ligands appear to be promising new therapies.

Fig. not shown. Structure and transcriptional activation of PPARs. (A) Generic schematic of the structure of the PPAR family of nuclear receptors. Indicated are the N–C terminal regions subdivided in to 4 domains: the A/B, N terminal domain [also called the activation function (AF)-1 domain]; C, the DNA binding domain; D, the F hinge_region; and E, the ligand binding domain (AF-2). (B) Generic scheme for the activation of a PPAR receptor as a transcription factor. PPAR activation leads to heterodimerization with RXR and an accumulation in the nucleus. Ligand activation of PPAR results in a change from a repressed binding protein complex which may contain histone deacetylases (HDAC), the nuclear receptor corepressor (NCo-R), and the silencing mediator of retinoid and thyroid signaling (SMRT) to an activation complex that may contain the histone acetylases, steroid receptor co-activator-1 (SRC-1), the PPAR binding protein (PBP), cAMP response element binding protein (CBP/p300), TATA box binding proteins, and RNA polymerase (RNA pol) III. The activated PPAR–RXR heterodimer complex binds to DNA sequences called PPAR response elements (PPRE) in target genes initiation their transcription.

Although the nature of true endogenous PPAR ligands are still not known (Bishop-Bailey & Wray, 2003), PPARs can be activated by a wide variety of F endogenous or pharmacological ligands. PPARα activators include a variety of endogenously present fatty acids, LTB4 and hydroxyeicosatetraenoic acids (HETEs), and clinically used drugs, such as the fibrates, a class of first-line drugs in the treatment of dyslipidemia. Similarly, PPARg can be activated by a number of ligands, including docosahexaenoic acid, linoleic acid, the anti-diabetic glitazones, used as insulin sensitizers, and a number of lipids, including oxidized LDL, azoyle-PAF, and eicosanoids, such as 5,8,11,14-eicosatetraynoic acid and the prostanoids PGA1, PGA2, PGD2, and its dehydration products of the PGJ series of cyclopentanones (e.g., 15 deoxy-D12,14-PGJ2). Dyslipidemia and insulin-dependent diabetes are commonly found existing together as part of the metabolic X syndrome.

Because PPARa and PPARg ligands independently are useful clinical drugs in the treatment of these respective disorders, synthetic dual PPARα/ϒ ligands have recently been developed and show a combined clinical efficacy. PPAR h/y activators include fatty acids and prostacyclin and synthetic compounds L-165,041, GW501516, compound F and L-783,483. Unlike PPARα or-ϒ, there are no PPAR h/y drugs in the clinic, although ligands are in phase II clinical trials for dyslipidemia (http://www.science.gsk.com/pipeline). Indeed, part of the challenge in determining the function of PPARh/y has been the identification and availability of new ligands with more potency and selectivity for use as pharmacological tools.

Fig. not shown. Mechanisms of the anti-inflammatory effects of PPARα. PPARα ligands inhibit the activities of NF-nB, AP-1, and T-bet within cells. In sites of local inflammation, tissue and endothelial cell activity is inhibited, and expressions of adhesion molecules (ICAM-1 and VCAM-1), pro-inflammatory cytokines (IL-1, -6, -8, -12, and TNFα), vasoactive mediators (inducible cyclo-oxygenase, inducible nitric oxide synthase, and endothelin-1; COX-2, iNOS, and ET-1), and proteases (MMP-9) are decreased. The inflammatory responses in leukocytes are also diminished. Monocyte/macrophage activity is decreased, and lipid metabolizing pathways increased, T- and B-lymphocyte proliferation and differentiation are inhibited, and T-lymphocyte and eosinophil chemotaxis reduced. Bold italic text indicates positive regulation by the PPAR, all other text indicates a negative regulation.

Fig. not shown. Mechanisms of the anti-inflammatory effects of PPAR h/y. PPAR h/y ligands inhibit the activities of NF-nB and release the suppressor BCL-6 from PPAR h/y. In sites of local inflammation, endothelial cell adhesion molecule (VCAM-1) and chemokine (MCP-1) are reduced. PPAR h/y and its endogenous ligand(s) are induced during the inflammatory response in keratinocytes, which then promotes cell survival (integrin-linked kinase—Akt pathway) and wound healing. The inflammatory responses in monocyte/ macrophages are modulated. In the absence of ligand, PPAR h/y sequesters BCL-6 and induces MCP-1, MCP-3, and IL-1h. When PPAR h/y ligand is given, BCL-6 is released and MCP-1, -3, and IL-1h levels are reduced. Bold italic text indicates positive regulation by the PPAR, all other text indicates a negative regulation.

Fig. not shown. Mechanisms of the anti-inflammatory effects of PPARg. PPARg ligands can inhibit the activities of NF-nB, AP-1, STAT-1, N-FAT, Erg-1, Jun, and GATA-3 within cells. In sites of local inflammation, tissue and endothelial cell activity is inhibited, and expression of adhesion molecules (ICAM-1), proinflammatory cytokines (IL-8, -12, and TNFα), chemokines (MCP-1, MCP-3, IP-10, Mig, and I-TAC), vasoactive mediators (inducible nitric oxide synthase and endothelin-1; iNOS and ET-1), and proteases (MMP-9) are decreased. The inflammatory responses in leukocytes are also diminished. Monocyte/ macrophage activity is decreased, T- and B-lymphocyte proliferation and differentiation are inhibited, and T-lymphocyte and eosinophil chemotaxis reduced. Platelet activity is inhibited and dendritic cell production of IL-12, and expression of CCL3, CCL5, and CD80 is reduced, so pro-inflammatory TH1 lymphocytes maturation is inhibited. Bold italic text indicates positive regulation by the PPAR, all other text indicates a negative regulation.

The PPARs are one of the most intensely studied members of the nuclear receptor gene family, and since their initial discovery just over decade ago, the PPARs have attracted an increasing amount of experimental and clinical research by investigators from different scientific areas. PPARs through their central roles in regulating energy homeostasis regulate physiological function in many cell types, tissues, and organ systems. Many disease states from carcinogenesis to inflammation have been linked to abnormalities in the function of PPAR-regulated transcription factors. PPARs are expressed or regulate pathophysiology of diverse human disorders including atherosclerosis, inflammation, obesity, diabetes, and the immune response. PPARs have beneficial effects in many inflammatory conditions, where they regulate cytokine production, adhesion molecule expression, fibrinolysis cell proliferation, apoptosis, and differentiation. Further studies and development of novel PPAR ligands and their selective modulators may lead to novel therapeutic agents in the many conditions associated with inflammatory processes.

Regulators of endothelial and epithelial barrier integrity and function in acute lung injury

Rudolf Lucas, Alexander D. Verin, Stephen M. Black, John D. Catravas
Biochemical Pharmacology 77 (2009) 1763–1772
http://dx.doi.org:/10.1016/j.bcp.2009.01.014

Pulmonary permeability edema is a major complication of acute lung injury (ALI), severe pneumonia and ARDS. This pathology can be accompanied by

(1) a reduction of alveolar liquid clearance capacity, caused by an inhibition of the expression of crucial sodium transporters, such as the epithelial sodium channel (ENaC) and the Na+-K+-ATPase,
(2) an epithelial and endothelial hyperpermeability and
(3) a disruption of the epithelial and endothelial barriers, caused by increased apoptosis or necrosis.

Since, apart from ventilation strategies, no standard treatment exists for permeability edema, the following chapters will review a selection of novel approaches aiming to improve these parameters in the capillary endothelium and the alveolar epithelium.

Apoptosis is an essential physiological process for the selective elimination of cells. However, the dysregulation of apoptotic pathways is thought to play an important role in the pathogenesis of ALI. Both delayed neutrophil apoptosis and enhanced endothelial/epithelial cell apoptosis have been identified in ALI/ARDS. In the case of neutrophils, which contribute significantly to ALI/ ARDS, studies in both animals and ARDS patients suggest that apoptosis is inhibited during the early stages (<2 h) of inflammation.

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily, that includes receptors for steroid hormones, thyroid hormones, retinoic acid, and fat-soluble vitamins. Since their discovery in 1990, increasing data has been published on the role of PPARs in diverse processes, including lipid and glucose metabolism, diabetes and obesity, atherosclerosis, cellular proliferation and differentiation, neurological diseases, inflammation and immunity. PPARs have both gene-dependent and gene-independent effects. Gene-dependent functions involve the formation of heterodimers with the retinoid X-receptor. Activation by PPAR ligands results in the binding of the heterodimer to peroxisome proliferator response elements, located in the promoter regions of PPAR-regulated genes. Gene independent effects involve the direct binding of PPARs to transcription factors, such as NF-kB, which then alters their binding to DNA promoter elements. PPARs can also bind and sequester various cofactors for transcription factors, and thus further alter gene expression. Importantly, the precise effects of PPARs vary greatly between cell types. To date, three subtypes of PPAR have been identified: α, β, and ϒ. There is increasing data suggesting that PPAR signaling may play an important role in the pathobiology of systemic vascular disease. However, there is less data implicating PPAR signaling in diseases of the lung.

A role for PPARs in the control of inflammation was first evidenced for PPARα, where mice deficient in PPARα exhibited an increased duration of ear-swelling in response to the proinflammatory mediator, LTB4. More recently, a number of studies in mice and in humans have shown that PPAR agonists exhibit anti-inflammatory effects under a wide range of conditions. There are two main mechanisms by which PPARs exert their anti-inflammatory effect. The first involves complex formation, and the inhibition of transcription factors that positively regulate the transcription of pro-inflammatory genes. These include nuclear factor-kB (NF-kB), signal transducers and activators of transcription (STATs), nuclear factor of activated T cells (NF-AT), CAAT/enhancer binding protein (C/EBP) and activator protein 1 (AP-1). These transcription factors are the main mediators of the major proinflammatory cytokines, chemokines, and adhesion molecules involved in inflammation. The second PPAR-mediated anti-inflammatory pathway is mediated by the sequestration of rate limiting, but essential, co-activators or co-repressors.

Recent studies have shown that PPAR signaling can attenuate the airway inflammation induced by LPS in the mouse. It was shown that mice treated with the PPARα agonist, fenofibrate, had decreases in both inflammatory cell infiltration and inflammatory mediators. Conversely, PPARα -/- mice have been shown to have a greater number of neutrophils and macrophages, and increased levels of inflammatory mediators in bronchoalveolar lavage fluids (BALF). Other PPAR agonists, such as rosiglitazone or SB 21994 have also been shown to reduce LPS-mediated ALI in the mouse lung. PPARϒ signaling has also been shown to be protective in regulating pulmonary inflammation associated with fluorescein isothiocyanate (FITC)-induced lung injury, with the PPARϒ ligand pioglitazone decreasing neutrophil infiltration. Collectively, these data suggest that therapeutic agents that activate either or both PPARα and PPARϒ could be beneficial for the treatment of ALI.

Permeability edema is characterized by a reduced alveolar liquid clearance capacity, combined with an endothelial hyperpermeability. Various signaling pathways, such as those involving reactive oxygen species (ROS), Rho GTPases and tyrosine phosphorylation of junctional proteins, converge to regulate junctional permeability, either by affecting the stability of junctional proteins or by modulating their interactions. The regulation of junctional permeability is mainly mediated by dynamic interactions between the proteins of the adherens junctions and the actin cytoskeleton. Actin-mediated endothelial cell contraction is the result of myosin light chain (MLC) phosphorylation by MLC kinase (MLCK) in a Ca2+/calmodulin-dependent manner. RhoA additionally potentiates MLC phosphorylation, by inhibiting MLC phosphatase activity through its downstream effector Rho kinase (ROCK). As such, actin/myosin-driven contraction will generate a contractile force that pulls VE-cadherin inward. This contraction will force VE-cadherin to dissociate from its adjacent partner, as such producing interendothelial gaps.

Vascular endothelial cells can be regulated by nucleotides released from platelets. During vascular injury, broken cells are also the source of the extracellular nucleotides. Furthermore, endothelium may provide a local source of ATP within vascular beds. Primary cultures of human endothelial cells derived from multiple blood vessels release ATP constitutively and exclusively across the apical membrane under basal conditions. Hypotonic challenge or the calcium agonists (ionomycin and thapsigargin) stimulate ATP release in a reversible and regulated manner. Enhanced release of pharmacologically relevant amounts of ATP was observed in endothelial cells under such stimuli as shear stress, lipopolysaccharide (LPS), and ATP itself. Pearson and Gordon demonstrated that incubation of aortic endothelial and smooth muscle cells with thrombin resulted in the specific release of ATP, which was converted to ADP by vascular hydrolases. Yang et al. showed that endothelial cells isolated from guinea pig heart release nucleotides in response to bradykinin, acetylcholine, serotonin and ADP. Nucleotide action is mediated by cell surface purinoreceptors. Once released from endothelial cells, ATP may act in the blood vessel lumen at P2 receptors on nearby endothelium downstream from the site of release. ATP is also degraded rapidly and its metabolites have also been recognized as signaling molecules, which can initiate additional receptor-mediated functions. These include ADP and the final hydrolysis product adenosine.

Signal transduction pathways implicated in ATP-mediated endothelial barrier enhancement

Signal transduction pathways implicated in ATP-mediated endothelial barrier enhancement

During the course of ALI, the alveolar space, as well as the interstitium, are sites of intense inflammation, leading to the local production of pro-inflammatory cytokines, such as IL-1β, TGF-β and TNF. The latter pleiotropic cytokine is a 51 kDa homotrimeric protein, binding to two types of receptors, i.e. TNF-R1 and TNF-R2 and which is mainly produced by activated macrophages and T cells. Soluble TNF, as well as the soluble TNF receptors 1 and 2, are generated upon cleavage of membrane TNF or of the membrane associated receptors, respectively, by the enzyme TNF-α convertase (TACE). TNF-R1, but not TNF-R2, contains a death domain, which signals apoptosis upon the formation of the Death Inducing Signaling Complex (DISC). In spite of its lack of a death domain, TNF-R2 can nevertheless be implicated in apoptosis induction, since its activation causes degradation of TNF Receptor Associated Factor 2 (TRAF2), an inhibitor of the TNF-R1-induced DISC formation. Moreover, apoptosis induction of lung microvascular endothelial cells by TNF was shown to require activation of both TNF receptors. TNF-R2 was also shown to be important for ICAM-1 upregulation in endothelial cells in vitro and in vivo, an activity important in the sequestration of leukocytes in the microvessels. Moreover, lung microvascular endothelial cells isolated from ARDS patients express significantly higher levels of TNF-R2 and of ICAM-1 than cells isolated from patients who had undergone a lobectomy for lung carcinoma, used as controls. These findings therefore suggest that ICAM-1 and TNF-R2 may have a particular involvement in the pathogenesis of acute lung injury.

Dichotomous activity of TNF in alveolar liquid clearance and barrier protection

Dichotomous activity of TNF in alveolar liquid clearance and barrier protection during ALI. TNF, which is induced during ALI, causes a downregulation of ENaC expression in type II alveolar epithelial cells, upon activating TNF-R1. Moreover, TNF increases permeability, by means of interfering with tight junctions (TJ) in both alveolar epithelial (AEC) and capillary endothelial cells (MVEC). ROS, the generation of which is frequently increased during ALI, were also shown to downregulate ENaC and Na+-K+-ATPase expression and moreover also lead to decreased endothelial barrier integrity. The TIP peptide, mimicking the lectin-like domain of TNF, is able to increase sodium uptake in alveolar epithelial cells and to restore endothelial barrier integrity, as such providing a significant protection against the development of permeability edema (red lines: inhibition, green arrows: activation).

Proposed mechanism of action for the anti-inflammatory and barrier-protective actions of hsp90 inhibitors.

Proposed mechanism of action for the anti-inflammatory and barrier-protective actions of hsp90 inhibitors.

Permeability edema represents a life-threatening complication of acute lung injury, severe pneumonia and ARDS, characterized by a combined dysregulation of pulmonary epithelial and endothelial apoptosis, endothelial barrier integrity and alveolar liquid clearance capacity. As such, it is likely that several of these parameters have to be targeted in order to obtain a successful therapy. This review focuses on a selection of recently discovered substances and mechanisms that might improve ALI therapy. As such, we have discussed the inhibition of apoptosis and necrosis occurring during ALI, by means of the restoration of Zn²⁺ homeostasis. PPARα and ϒ agonists can represent therapeutically promising molecules, since they inhibit transcription factors as well as essential co-activators involved in the activation of pro-inflammatory cytokines, chemokines and adhesion molecules, all of which are implicated in ALI. Apart from inducing a potent inhibition of inflammation upon interfering with NF-kB activation, hsp90 inhibitors were shown to prevent and restore endothelial barrier integrity. These agents are able to significantly improve survival and lung function during LPS-induced ALI. A restoration of endothelial barrier integrity during ALI can also be obtained upon increasing extracellular levels of ATP or adenosine, which activate the purinoreceptors P2Y and P1A2, respectively, leading to a decrease in myosin light chain phosphorylation and an increase in MLC phosphatase 1 activity. The pro-inflammatory cytokine TNF is involved in endothelial apoptosis and hyperpermeability, as well as in the reduction of alveolar liquid clearance, upon activating its receptors. However, apart from its receptor binding sites, TNF harbors a lectin-like domain, which can be mimicked by the TIP peptide. This peptide has been shown to increase alveolar liquid clearance and moreover induces endothelial barrier protection. As such, TNF can be considered as a moonlighting cytokine, combining both positive and negative activities for permeability edema generation within one molecule.

The protective effect of CDDO-Me on lipopolysaccharide-induced acute lung injury in mice

Tong Chen, Yi Moua, Jiani Tan, LinlinWei, Yixue Qiao, Tingting Wei, et al.
International Immunopharmacology 25 (2015) 55–64
http://dx.doi.org/10.1016/j.intimp.2015.01.011

ALI is a clinical syndrome characterized by a disruption of epithelial integrity, neutrophil accumulation, noncardiogenic pulmonary edema, severe hypoxemia and an intense pulmonary inflammatory response with a wide array of increasing severity of lung parenchymal injury. Previous studies have shown that lots of pathogenesis contribute to ALI, such as oxidant/antioxidant dysfunction, dysregulation of inflammatory/anti-inflammatory pathway, upregulation of chemokine production and adhesion molecules. However, to date there is no effective medicine to control ALI. Lipopolysaccharide (LPS) is a main component of the outer membrane of Gram negative bacteria. It has been reported to activate toll like receptors 4 (TLR4) and to stimulate the release of inflammatory mediators inducing ALI-like symptoms. Intratracheal administration of LPS has been used to construct animal models of ALI.

The biological importance of naturally occurring triterpenoids has long been recognized. Oleanolic acid, exhibiting modest biological activities, has been marketed in China as an oral drug for the treatment of liver disorders in humans. Among its derivatives, bardoxolonemethyl (2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid methylester) CDDO-Me, had completed a successful phase I clinical trial for the treatment of cancer and started a phase II trial for the treatment of patients with pulmonary arterial hypertension. For its broad spectrum antiproliferative and anti-tumorigenic activities, CDDO-Me has also been reported to possess a number of pharmacological activities such as antioxidant, anti-tumor and anti-inflammatory effects. However, the mechanisms by which CDDO-Me exerted its anti-inflammatory effects on macrophage were insufficiently elucidated. More importantly, there is no available report to evaluate its therapeutic effect on acute lung injury.

CDDO-Me, initiated in a phase II clinical trial, is a potential useful therapeutic agent for cancer and inflammatory dysfunctions, whereas the therapeutic efficacy of CDDO-Me on LPS-induced acute lung injury (ALI) has not been reported as yet. The purpose of the present study was to explore the protective effect of CDDO-Me on LPS-induced ALI in mice and to investigate its possible mechanism. BalB/c mice received CDDO-Me (0.5 mg/kg, 2 mg/kg) or dexamethasone (5 mg/kg) intraperitoneally 1 h before LPS stimulation and were sacrificed 6 h later. W/D ratio, lung MPO activity, number of total cells and neutrophils, pulmonary histopathology, IL-6, IL-1β, and TNF-α in the BALF were assessed. Furthermore, we estimated iNOS, IL-6, IL-1β, and TNF-α mRNA expression and NO production as well as the activation of the three main MAPKs, AkT, IκB-α and p65. Pretreatment with CDDO-Me significantly ameliorated W/D ratio, lung MPO activity, inflammatory cell infiltration, and inflammatory cytokine production in BALF from the in vivo study. Additionally, CDDO-Me had beneficial effects on the intervention for pathogenesis process at molecular, protein and transcriptional levels in vitro. These analytical results provided evidence that CDDO-Me could be a potential therapeutic candidate for treating LPS-induced ALI.

Effects of CDDO-Me on LPS-mediated lung histopathologic changes in lung tissues. (A) The lung section from the control mice; (B) the lung section from the mice administered with LPS (8 mg/kg); (C) the lung section from the mice administered with dexamethasone (5 mg/kg) and LPS (8 mg/kg); (D) the lung section from the mice administered with CDDO-Me (0.5mg/kg) and LPS (8mg/kg); (E) the lung section from the mice administered with CDDO-Me (2mg/kg) and LPS (8mg/kg); (hematoxylin and eosin staining, magnification 200×). Control group: the green arrow indicated alveolar wall, no hyperemia. All the other groups: The black arrow indicated the inflammatory cell infiltration; the green arrow indicated alveolar wall hyperemia.

The impact of cardiac dysfunction on acute respiratory distress syndrome and mortality in mechanically ventilated patients with severe sepsis and septic shock: An observational study

Brian M. Fuller, Nicholas M. Mohr, Thomas J. Graetz, et al.
Journal of Critical Care 30 (2015) 65–70
http://dx.doi.org/10.1016/j.jcrc.2014.07.027

Purpose: Acute respiratory distress syndrome (ARDS) is associated with significant mortality and morbidity in survivors. Treatment is only supportive, therefore elucidating modifiable factors that could prevent ARDS could have a profound impact on outcome. The impact that sepsis-associated cardiac dysfunction has on ARDS is not known. Materials and Methods: In this retrospective observational cohort study of mechanically ventilated patients with severe sepsis and septic shock, 122 patients were assessed for the impact of sepsis-associated cardiac dysfunction on incidence of ARDS (primary outcome) and mortality. Results: Sepsis-associated cardiac dysfunction occurred in 44 patients (36.1%). There was no association of sepsis-associated cardiac dysfunction with ARDS incidence (p= 0.59) or mortality, and no association with outcomes in patients that did progress to ARDS after admission. Multivariable logistic regression demonstrated that higher BMI was associated with progression to ARDS (adjusted OR 11.84, 95% CI 1.24 to 113.0, p= 0.02). Conclusions: Cardiac dysfunction in mechanically ventilated patients with sepsis did not impact ARDS incidence, clinical outcome in ARDS patients, or mortality. This contrasts against previous investigations demonstrating an influence of nonpulmonary organ dysfunction on outcome in ARDS. Given the frequency of ARDS as a sequela of sepsis, the impact of cardiac dysfunction on outcome should be further studied.

Suppression of NF-κβ pathway by crocetin contributes to attenuation of lipopolysaccharide-induced acute lung injury in mice

Ruhui Yang, Lina Yang, Xiangchun Shen, Wenyuan Cheng, et al.
European Journal of Pharmacology 674 (2012) 391–396
http://dx.doi.org:/10.1016/j.ejphar.2011.08.029

Crocetin, a carotenoid compound, has been shown to reduce expression of inflammation and inhibit the production of reactive oxygen species. In the present study, the effect of crocetin on acute lung injury induced by lipopolysaccharide (LPS) was investigated in vivo. In the mouse model, pretreatment with crocetin at dosages of 50 and 100 mg/kg reduced the LPS-induced lung edema and histological changes, increased LPS-impaired superoxide dismutase (SOD) activity, and decreased lung myeloperoxidase (MPO) activity. Furthermore, treatment with crocetin significantly attenuated LPS-induced mRNA and the protein expressions of interleukin-6 (IL-6), macrophage chemoattractant protein-1 (MCP-1), and tumour necrosis factor-α (TNF-α) in lung tissue. In addition, crocetin at different dosages reduced phospho-IκB expression and NF-κB activity in LPS-induced lung tissue alteration. These results indicate that crocetin can provide protection against LPS-induced acute lung injury in mice.

Sauchinone, a lignan from Saururus chinensis, attenuates neutrophil pro-inflammatory activity and acute lung injury

Hui-Jing Han, Mei Li, Jong-Keun Son, Chang-Seob Seo, et al.
International Immunopharmacology 17 (2013) 471–477
http://dx.doi.org/10.1016/j.intimp.2013.07.011

Previous studies have shown that sauchinone modulates the expression of inflammatory mediators through mitogen-activated protein kinase (MAPK) pathways in various cell types. However, little information exists about the effect of sauchinone on neutrophils, which play a crucial role in inflammatory process such as acute lung injury (ALI). We found that sauchinone decreased the phosphorylation of p38 MAPK in lipopolysaccharide (LPS)-stimulated murine bone marrow neutrophils, but not ERK1/2 and JNK. Exposure of LPS-stimulated neutrophils to sauchinone or SB203580, a p38 inhibitor, diminished production of tumor necrosis factor (TNF)-α and macrophage inflammatory protein (MIP)-2 compared to neutrophils cultured with LPS. Treatment with sauchinone decreased the level of phosphorylated ribosomal protein S6 (rpS6) in LPS-stimulated neutrophils. Systemic administration of sauchinone to mice led to reduced levels of phosphorylation of p38 and rpS6 in mice lungs given LPS, decreased TNF-α and MIP-2 production in bronchoalveolar lavage fluid, and also diminished the severity of LPS-induced lung injury, as determined by reduced neutrophil accumulation in the lungs, wet/dry weight ratio, and histological analysis. These results suggest that sauchinone diminishes LPS-induced neutrophil activation and ALI.

In the present study, the systemic administration of sauchinone decreased the phosphorylation of p38 MAPK and rpS6 in mice lungs subjected to LPS and diminished the severity of LPS-induced ALI. Neutrophils play an important role in acute inflammatory processes, such as ALI, which was demonstrated by various experimental models. Previous reports suggested that p38 MAPK inhibition of murine neutrophils could lead to the loss of chemotaxis toward MIP-2, as well as the loss of TNF-αandMIP-2 production in response to LPS, and also attenuated neutrophil accumulation in LPS-induced ALI models. Therefore, the beneficial effects of sauchinone on LPS-induced ALI are likely associated with decreases in the production of pro-inflammatory mediators by neutrophils, consistent with our in vitro experiments. However, we cannot exclude that the effects of sauchinone on reducing the release of TNF-α and MIP-2 in mice lungs subjected to LPS, with the resultant prevention of ALI, could be affected by various pulmonary cell populations, such as alveolar macrophages. Also, the inhibitory effects of sauchinone on NF-κB activation through various pulmonary cell populations (Supplemental Fig. S2), in addition to p38MAPK activity in mouse lungs given LPS, might enhance the anti-inflammatory action of sauchinone in mouse lungs subjected to LPS. In conclusion, we found that sauchinone significantly diminished the release of inflammatory mediators in isolated neutrophils and lungs subjected to LPS. The anti-inflammatory action of sauchinone was associated with the prevention of p38 MAPK and rpS6 activation. These findings suggest that sauchinone may be an appropriate pharmacological candidate for the treatment of ALI as well as other neutrophil driven acute inflammatory diseases.
Supplementary data to this article can be found online at
http://dx.doi.org/10.1016/j.intimp.2013.07.011

Protective effect of dexmedetomidine in a rat model of α-naphthylthiourea- induced acute lung injury

Volkan Hancı, Gamze Yurdakan, Serhan Yurtlu, et al.
J Surg Res 178 (2012):424-430
http://dx.doi.org:/10.1016/j.jss.2012.02.027

Background: We assessed the effects of dexmedetomidine in a rat model of a-naphthylthiourea (ANTU)einduced acute lung injury. Methods: Forty Wistar Albino male rats weighing 200e240 g were divided into 5 groups (n = 8 each), including a control group. Thus, there were one ANTU group and three dexmedetomidine groups (10-, 50-, and 100-mg/kg treatment groups), plus a control group. The control group provided the normal base values. The rats in the ANTU group were given 10 mg/kg of ANTU intraperitoneally and the three treatment groups received 10, 50, or 100 mg/kg of dexmedetomidine intraperitoneally 30 min before ANTU application. The rat body weight (BW), pleural effusion (PE), and lung weight (LW) of each group were measured 4 h after ANTU administration. The histopathologic changes were evaluated using hematoxylin-eosin staining. Results: The mean PE, LW, LW/BW, and PE/BW measurements in the ANTU group were significantly greater than in the control groups and all dexmedeto-midine treatment groups (P < 0.05). There were also significant decreases in the mean PE, LW, LW/BW and PE/BW values in the dexmedetomidine 50-mg/kg group compared with those in the ANTU group (P < 0.01). The inflammation, hemorrhage, and edema scores in the ANTU group were significantly greater than those in the control or dexmedetomidine 50-mg/kg group (P < 0.01). Conclusion: Dexmedetomidine treatment has demonstrated a potential benefit by preventing ANTU-induced acute lung injury in an experimental rat model. Dexmedetomidine could have a potential protective effect on acute lung injury in intensive care patients.

Protective effects of Isofraxidin against lipopolysaccharide-induced acute lung injury in mice

Xiaofeng Niu, YuWang, Weifeng Li, Qingli Mu, et al.
International Immunopharmacology 24 (2015) 432–439
http://dx.doi.org/10.1016/j.intimp.2014.12.041

Acute lung injury (ALI) is a life-threatening disease characterized by serious lung inflammation and increased capillary permeability, which presents a high mortality worldwide. Isofraxidin (IF), a Coumarin compound isolated from the natural medicinal plants such as Sarcandra glabra and Acanthopanax senticosus, has been reported to have definite anti-bacterial, anti-oxidant, and anti-inflammatory activities. However, the effects of IF against lipopoly-saccharide-induced ALI have not been clarified. The aim of the present study is to explore the protective effects and potential mechanism of IF against LPS-induced ALI in mice. In this study, We found that pretreatment with IF significantly lowered LPS-induced mortality and lung wet-to-dry weight (W/D) ratio and reduced the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and prostaglandin E2 (PGE2) in serum and bronchoalveolar lavage fluid (BALF). We also found that total cells, neutrophils and macrophages in BALF,MPO activity in lung tissues were markedly decreased. Besides, IF obviously inhibited lung histopathological changes and cyclooxygenase-2 (COX-2) protein expression. These results suggest that IF has a protective effect against LPS induced ALI, and the protective effect of IF seems to result from the inhibition of COX-2 protein expression in the lung, which regulates the production of PGE2.

Ingestion of LPS stimulates vascular permeability, promotes inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) from blood into lung tissues and activates numerous inflammatory cells such as neutrophils and macrophages. In macrophages, LPS challenge induces the transcription of gene encoding pro-inflammatory protein, which leads to cytokine release and synthesis of enzymes, such as cyclo-oxygenase-2 (COX-2). COX-2 usually can’t be found in normal tissues, but widely induced by pro-inflammatory stimuli, such as cytokines, endotoxins, and growth factors. COX-2 plays a vital role in the regulation of inflammatory process by modulating the production of prostaglandin E2 (PGE2). PGE2, induced by cytokines and other initiator, is an inflammatory mediator which is produced in the regulation of COX-2. Previous researches demonstrated that inhibition of COX-2 produced a dramatically anti-inflammatory effect with little gastrointestinal toxicity. Therefore, inhibition of COX-2 protein expression has far-reaching significance in the treatment of ALI.

effects of IF on LPS-induced mortality in ALI mice

The effects of IF on LPS-induced mortality in ALI mice (n = 12/group). IF (5, 10, 15 mg/kg, i.p.) or DEX (5 mg/kg, i.p.) were given to mice 1 h prior to LPS challenge. The mortalities were observed at 0, 12, 24, 36, 48, 60, and 72 h. ###P = 0.001 when compared with the control group; *P = 0.05, **P = 0.01, and ***P = 0.001 when compared with the LPS group.

Protective effects of intranasal curcumin on paraquot induced acute lung injury (ALI) in mice

Namitosh Tyagi, Asha Kumaria, D. Dash, Rashmi Singh
Environment Toxicol & Pharmacol 38 (2014) 913–921
http://dx.doi.org/10.1016/j.etap.2014.10.003

Paraquot (PQ) is widely and commonly used as herbicide and has been reported to be hazardous as it causes lung injury. However, molecular mechanism underlying lung toxicity caused by PQ has not been elucidated. Curcumin, a known anti-inflammatory molecule derived from rhizomes of Curcuma longa has variety of pharmacological activities including free-radical scavenging properties but the protective effects of curcumin on PQ-induced acute lung injury (ALI) have not been studied. In this study, we aimed to study the effects of curcumin on ALI caused by PQ in male parke’s strain mice which were challenged acutely byPQ (50 mg/kg, i.p.) with or without curcumin an hour before (5 mg/kg, i.n.) PQ intoxication. Lung specimens and the bronchoalveolar lavage fluid (BALF) were isolated for pathological and biochemical analysis after 48 h of PQ exposure. Curcumin administration has significantly enhanced superoxide dismutase (SOD) and catalase activities. Lung wet/dry weight ratio, malondialdehyde (MDA) and lactate dehydrogenase (LDH) content, total cell number and myeloperoxidase (MPO) levels in BALF as well as neutrophil infiltration were attenuated by curcumin. Pathological studies also revealed that intranasal curcumin alleviate PQ-induced pulmonary damage and pro-inflammatory cytokine levels like tumor necrosis factor-α (TNF-α) and nitric oxide (NO). These results suggest that intranasal curcumin may directly target lungs and curcumin inhalers may prove to be effective in PQ-induced ALI treatment in near future.

Phillyrin attenuates LPS-induced pulmonary inflammation via suppression of MAPK and NF-κB activation in acute lung injury mice

Wei-ting Zhong, Yi-chun Wu, Xian-xing Xie, Xuan Zhou, et al.
Fitoterapia 90 (2013) 132–139
http://dx.doi.org/10.1016/j.fitote.2013.06.003

Phillyrin (Phil) is one of the main chemical constituents of Forsythia suspensa (Thunb.), which has shown to be an important traditional Chinese medicine. We tested the hypothesis that Phil modulates pulmonary inflammation in an ALI model induced by LPS. Male BALB/c mice were pretreated with or without Phil before respiratory administration with LPS, and pretreated with dexamethasone as a control. Cytokine release (TNF-α, IL-1β, and IL-6) and amounts of inflammatory cell in bronchoalveolar lavage fluid (BALF) were detected by ELISA and cell counting separately. Pathologic changes, including neutrophil infiltration, interstitial edema, hemorrhage, hyaline membrane formation, necrosis, and congestion during acute lung injury in mice were evaluated via pathological section with HE staining. To further investigate the mechanism of Phil anti-inflammatory effects, activation of MAPK and NF-κB pathways was tested by western blot assay. Phil pretreatment significantly attenuated LPS-induced pulmonary histopathologic changes, alveolar hemorrhage, and neutrophil infiltration. The lung wet-to-dry weight ratios, as the index of pulmonary edema, were markedly decreased by Phil retreatment. In addition, Phil decreased the production of the proinflammatory cytokines including (TNF-α, IL-1β, and IL-6) and the concentration of myeloperoxidase (MPO) in lung tissues. Phil pretreatment also significantly suppressed LPS-induced activation of MAPK and NF-κB pathways in lung tissues. Taken together, the results suggest that Phil may have a protective effect on LPS-induced ALI, and it potentially contributes to the suppression of the activation of MAPK and NF-κB pathways. Phil may be a new preventive agent of ALI in the clinical setting.

A mass of studies have been reported basically on alleviating LPS-induced acute lung injury in models. Phillyrin (Fig. 1), a lignin, is one of the main chemical constituents of Forsythia suspensa (Thunb.), which is an important traditional Chinese medicine (“Lianqiao” in Chinese), and has long been used for gonorrhea, erysipelas, inflammation, pyrexia and ulcer. Previous studies indicated that Phil significantly inhibited NO production in LPS-activated macrophage cells. But there is not much evidence showing the anti-inflammatory properties of phillyrin. In the present study, we sought to investigate the effects of phillyrin on LPS-induced pulmonary inflammation in mice.

Fig. not shown. A: Effects of Phil on histopathological changes in lung tissues in LPS-induced ALI mice. Mice were given an intragastric administration of Phil (10 and 20 mg/kg) or Dex (5 mg/kg) 1 h prior to an intranasal administration of LPS. Then mice were anesthetized and lung tissue samples were collected at 6 h after LPS challenge for histological evaluation. These representative histological changes of the lung were obtained from mice of different groups (hematoxylin and eosin staining, original magnification 200×, Scale bar: 50 μm). B: Effects of Phil on LPS-induced lung morphology. The slides were histopathologically evaluated using a semi-quantitative scoring method. Lung injury was graded from 0 (normal) to 4 (severe) in four categories: congestion, edema, interstitial inflammation and inflammatory cell infiltration. The total lung injury score was calculated by adding up the individual scores of each category. The values presented are the means ± S.E.M. (n = 4–6 in each group). ##P b 0.01 vs. the control group, **P b 0.01 vs. the LPS group. Cont: control group; LPS: LPS group; Phil + LPS: Phil + LPS group; Dex + LPS: Dex + LPS group.

In summary, the present study indicated that Phil has a protective effect on LPS-induced acute lung injury. Phil significantly attenuated histopathological changes initiated by LPS via reducing over inflammatory responses. We also demonstrated that MAPK and NF-κB signaling pathways are the important targets of Phil to perform its actions. Phil acts by preventing NF-κB translocation to the nucleus or inhibiting the activation of MAPKs directly or indirectly, which is to be investigated in further studies. All these results suggest that Phil may be a new therapeutic agent for the prevention of inflammation during acute lung injury.

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Depth Underwater and Underground

Posted in Amino acids, Best evidence, Biochemical pathways, Biological Networks, Biological Networks, Gene Regulation and Evolution, Biomedical Measurement Science, Cell Biology, Cell Biology, Signaling & Cell Circuits, Curation, Curation methodology, Developmental biology, Diabetes Mellitus, Dialectic, Discovery process, Electrophysiology, Evolutionary cognition, Explanatory, Fatty acids, Gene Regulation, Gene Regulation and Evolution, Genome Biology, Hematopoiesis, Historical relevance, Innovations, Lipid metabolism, Metabolism, Mutant Gene Expression, Myocardial Ischemia, Myocardial Metabolism, Na-K transport, Na-K-ATPase, Neurological Diseases, Nutrition, Proteins, Proteomics, Signaling & Cell Circuits, Theoretic convergence, Translational Research, Translational Science, tagged Biochemistry and Molecular Biology, Bioinformatics, Biology, blind mole rat, Cell Biology, cellular stress, climate, decompression, Hemoglobin, human diving, mtDNA, myoglobin, nitrogen sickness, oxygen delivery, sea lion, seals and otters, whales on February 24, 2015| Leave a Comment »

Depth Underwater and Underground

Writer and Curator: Larry H. Bernstein, MD, FCAP

Introduction

Deep diving for mammals is dangerous for humans and land based animals for too long, and it has dangerous consequences, most notable in nitrogen emboli with very deep underwater diving. Other mammals live in water and have adapted to a water habitat. This is another topic that needs further exploration.

Deep diving has different meanings depending on the context. Even in recreational diving the meaning may vary:

In recreational diving, a depth below about 30 metres (98 ft), where nitrogen narcosis becomes a significant hazard for most divers, may be considered a “deep dive”

In technical diving, a depth below about 60 metres (200 ft) where hypoxic breathing gas becomes necessary to avoid oxygen toxicity may be considered a “deep dive”.

Early experiments carried out by Comex S.A. (Compagnie maritime d’expertises) using hydrox and trimix attained far greater depths than any recreational technical diving. One example being the Comex Janus IV open-sea dive to 501 metres (1,644 ft) in 1977. The open-sea diving depth record was achieved in 1988 by a team of Comex divers who performed pipe line connection exercises at a depth of 534 metres (1,752 ft) in the Mediterranean Sea as part of the Hydra 8 program. These divers needed to breathe special gas mixtures because they were exposed to very high ambient pressure (more than 50 times atmospheric pressure).

Then there is the adaptation to the water habitat as a living environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.

http://en.wikipedia.org/wiki/Deep_diving

Marine ecosystems are part of the earth’s aquatic ecosystem. The habitats that make up this vast system range from the productive nearshore regions to the barren ocean floor. The marine waters may be fully saline, brackish or nearly fresh. The saline waters have a salinity of 35-50 ppt (= parts per thousand). The freshwater has a salinity of less than 0.5 ppt. The brackish water lies in between these 2. Marine habitats are situated from the coasts, over the continental shelf to the open ocean and deep sea. The ecosystems are sometimes linked with each other and are sometimes replacing each other in other geographical regions. The reason why habitats differ from another is because of the physical factors that influence the functioning and diversity of the habitats. These factors are temperature, salinity, tides, currents, wind, wave action, light and substrate.

Marine ecosystems are home to a host of different species ranging from planktonic organisms that form the base of the marine food web to large marine mammals. Many species rely on marine ecosystems for both food and shelter from predators. They are very important to the overall health of both marine and terrestrial environments. Coastal habitats are those above the spring high tide limit or above the mean water level in non-tidal waters. They are close to the sea and include habitats such as coastal dunes and sandy shores, beaches , cliffs and supralittoral habitats. Coastal habitats alone account for approximately 30% of all marine biological productivity.

http://www.marbef.org/wiki/marine_habitats_and_ecosystems

All plant and animal life forms are included from the microscopic picoplankton all the way to the majestic blue whale, the largest creature in the sea—and for that matter in the world. It wasn’t until the writings of Aristotle from 384-322 BC that specific references to marine life were recorded. Aristotle identified a variety of species including crustaceans, echinoderms, mollusks, and fish.
Today’s classification system was developed by Carl Linnaeus external link as an important tool for use in the study of biology and for use in the protection of biodiversity. Without very specific classification information and a naming system to identify species’ relationships, scientists would be limited in attempts to accurately describe the relationships among species. Understanding these relationships helps predict how ecosystems can be altered by human or natural factors.

Preserving biodiversity is facilitated by taxonomy. Species data can be better analyzed to determine the number of different species in a community and to determine how they might be affected by environmental stresses. Family, or phylogenetic, trees for species help predict environmental impacts on individual species and their relatives.

http://marinebio.org/oceans/marine-taxonomy/

For generations, whales and other marine mammals have intrigued humans. 2,400 years ago, Aristotle, a Greek scientist and philosopher, recognized that whales are mammals, not fish, because they nurse their young and breathe air like other mammals. There are numerous myths and legends surrounding marine mammals. The Greeks believed that killing a dolphin was as bad as murdering a human. An Amazon legend said that river dolphins came to shore dressed as men to woo pretty girls during fiestas. During the Middle Ages, there were numerous legends surrounding the narwhals’ amazing tusk, which was thought to have come from the unicorn.

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Marine mammals evolved from their land dwelling ancestors over time by developing adaptations to life in the water. To aid swimming, the body has become streamlined and the number of body projections has been reduced. The ears have shrunk to small holes in size and shape. Mammary glands and sex organs are not part of the external physiology, and posterior (hind) limbs are no longer present.

Mechanisms to prevent heat loss have also been developed. The cylindrical body shape with small appendages reduces the surface area to volume ratio of the body, which reduces heat loss. Marine mammals also have a counter current heat exchange mechanism created by convergent evolution external link where the heat from the arteries is transferred to the veins as they pass each other before getting to extremities, thus reducing heat loss. Some marine mammals also have a thick layer of fur with a water repellent undercoat and/or a thick layer of blubber that can’t be compressed. The blubber provides insulation, a food reserve, and aids with buoyancy. These heat loss adaptations can also lead to overheating for animals that spend time out of the water. To prevent overheating, seals or sea lions will swim close to the surface with their front flippers waving in the air. They also flick sand onto themselves to keep the sun from directly hitting their skin. Blood vessels can also be expanded to act as a sort of radiator.

One of the major behavioral adaptations of marine mammals is their ability to swim and dive. Pinnipeds swim by paddling their flippers while sirenians and cetaceans move their tails or flukes up and down.

Some marine mammals can swim at relatively high speeds. Sea lions swim up to 35 kph and orcas can reach 50 kph. The fastest marine mammal, however, is the common dolphin, which reaches speeds up to 64 kph. While swimming, these animals take very quick breaths. For example, fin whales can empty and refill their huge lungs in less than 2 seconds. Marine mammals’ larynx and esophagus close automatically when they open their mouths to catch prey during dives. Oxygen is stored in hemoglobin in the blood and in myoglobin in the muscles. The lungs are also collapsible so that air is pushed into the windpipe preventing excess nitrogen from being absorbed into the tissues. Decreasing pressure can cause excess nitrogen to expand in the tissues as animals ascend to shallower depths, which can lead to decompression sickness, aka “the bends.” Bradycardia, the reduction of heart rate by 10 to 20%, also takes place to aid with slowing respiration during dives and the blood flow to non-essential body parts. These adaptations allow sea otters to stay submerged for 4 to 5 minutes and dive to depths up to 55 m. Pinnipeds can often stay down for 30 minutes and reach average depths of 150-250 m. One marine mammal with exceptional diving skills is the Weddell seal, which can stay submerged for at least 73 minutes at a time at depths up to 600 m. The length and depth of whale dives depends on the species. Baleen whales feed on plankton near the surface of the water and have no need to dive deeply so they are rarely seen diving deeper than 100 m external link. Toothed whales seek larger prey at deeper depths and some can stay down for hours at depths of up to 2,250 m external link.

http://marinebio.org/oceans/marine-mammals/

Human Experience

Albert Behnke: Nitrogen Narcosis

Casey A. Grover and David H. Grover
The Journal of Emergency Medicine, 2014; 46(2):225–227
http://dx.doi.org/10.1016/j.jemermed.2013.08.080

As early as 1826, divers diving to great depths noted that descent often resulted in a phenomenon of intoxication and euphoria. In 1935, Albert Behnke discovered nitrogen as the cause of this clinical syndrome, a condition now known as nitrogen narcosis. Nitrogen narcosis consists of the development of euphoria, a false sense of security, and impaired judgment upon underwater descent using compressed air below 34 atmospheres (99 to 132 feet). At greater depths, symptoms can progress to loss of consciousness. The syndrome remains relatively unchanged in modern diving when compressed air is used. Behnke’s use of non-nitrogencontaining gas mixtures subsequent to his discovery during the 1939 rescue of the wrecked submarine USS Squalus pioneered the use of non-nitrogencontaining gas mixtures, which are used by modern divers when working at great depth to avoid the effects of nitrogen narcosis.

Behnke’s first duty station as a licensed physician was as assistant medical officer for Submarine Division 20 in San Diego, which was then commanded by one of the Navy’s rising stars, Captain Chester W. Nimitz of World War II fame.
In this setting, Dr. Behnke spent his free time constructively by learning to dive, using the traditional ‘‘hard-hat’’ gear aboard the USS Ortalon, a submarine rescue vessel to which he also rotated. Diving was not a notable specialty of the Navy at the time, and the service was slow in developing the infrastructure for it. Dr. Behnke devoted his efforts to research on the topic of diving medicine, as well as developing a more sound understanding of the biophysics of diving. In 1932, he wrote a letter to the Surgeon General describing some of his observations on arterial gas embolism, which earned him some accolades from the Navy and resulted in his transfer to Harvard’s School of Public Health as a graduate fellow. After 2 years at Harvard, the Navy assigned duty to Dr. Behnke at the Navy’s submarine escape training tower at Pearl Harbor. He worked extensively here on developing techniques for rescuing personnel from disabled submarines on the sea floor. In 1937, he was one of three Navy physicians assigned to the Navy’s Experimental Diving Unit. This team worked on improving the rescue system, plus updating the diving recompression tables originally developed by the British in 1908.

The intoxicating effects of diving were first described by a French physician named Colladon in 1826, who reported that descent in a diving bell resulted in his feeling a ‘‘state of excitement as though I had drunk some alcoholic liquor’’.
The etiology of this phenomenon remained largely unknown until the 1930s, when the British military researcher Damant again highlighted the issue, and reported very unpredictable behavior in his divers during descents as deep as 320 feet during the British Admiralty Deep Sea diving trials. Two initial theories arose as to the etiology for this effect, the first being from psychological causes by Hill and Phillip in 1932, and the second being from oxygen toxicity by Haldane in 1935.

Dr. Behnke and his colleagues at the Harvard School of Public Health had another idea as to the etiology of this phenomenon. In 1935, based on observation of individuals in experiments with a pressure chamber, Dr. Behnke published an article in the American Journal of Physiology in which he posited that nitrogen was the etiology of the intoxicating effects of diving.

Nitrogen narcosis, described as ‘‘rapture of the deep’’ by Jacques Cousteau, still remains a relatively common occurrence in modern diving, despite major advances in diving technology since Behnke’s initial description of the pathophysiologic cause of the condition in 1935. The development of symptoms of this condition varies from diver to diver, but usually begins when a depth of 4 atmospheres (132 feet) is reached in divers using compressed air. More sensitive divers can develop symptoms at only 3 atmospheres (99 feet), and other divers may not be affected up to depths as high as 6 atmospheres (198 feet). Interestingly, tolerance to nitrogen narcosis can be developed by frequent diving and exposure to the effects of compressed air at depth.

Acott C. A brief history of diving and decompression illness. SPUMS J 1999;29:98–109.
2. Bornmann R. Dr. Behnke, founder of UHMS, dies. Pressure 1992; 21:14.
3. Behnke AR, Thomson RM, Motley P. The psychologic effects from breathing air at 4 atmospheric pressures. Am J Physiol 1935; 112:554–8.
4. Behnke AR, Johnson FS, Poppen JR, Motley P. The effect of oxygen on man at pressures from 1 to 4 atmospheres. AmJ Physiol 1934; 110:565–72.

Exhaled nitric oxide concentration and decompression-induced bubble formation: An index of decompression severity in humans?

J.-M. Pontier, Buzzacott, J. Nastorg, A.T. Dinh-Xuan, K. Lambrechts
Nitric Oxide 39 (2014) 29–34
http://dx.doi.org/10.1016/j.niox.2014.04.005

Introduction: Previous studies have highlighted a decreased exhaled nitric oxide concentration (FE NO) in divers after hyperbaric exposure in a dry chamber or following a wet dive. The underlying mechanisms of this decrease remain however unknown. The aim of this study was to quantify the separate effects of submersion, hyperbaric hyperoxia exposure and decompression-induced bubble formation on FE NO after a wet dive.
Methods: Healthy experienced divers (n = 31) were assigned to either

a group making a scuba-air dive (Air dive),
a group with a shallow oxygen dive protocol (Oxygen dive) or

a group making a deep dive breathing a trimix gas mixture (deep-dive).
Bubble signals were graded with the KISS score. Before and after each dive FE NO values were measured using a hand-held electrochemical analyzer.
Results: There was no change in post-dive values of FE NO values (expressed in ppb = parts per billion) in the Air dive group (15.1 ± 3.6 ppb vs. 14.3 ± 4.7 ppb, n = 9, p = 0.32). There was a significant decrease in post-dive values of FE NO in the Oxygen dive group (15.6 ± 6 ppb vs. 11.7 ± 4.7 ppb, n = 9, p = 0.009). There was an even more pronounced decrease in the deep dive group (16.4 ± 6.6 ppb vs. 9.4 ± 3.5 ppb, n = 13, p < 0.001) and a significant correlation between KISS bubble score >0 (n = 13) and percentage decrease in post-dive FE NO values (r = -0.53, p = 0.03). Discussion: Submersion and hyperbaric hyperoxia exposure cannot account entirely for these results suggesting the possibility that, in combination, one effect magnifies the other. A main finding of the present study is a significant relationship between reduction in exhaled NO concentration and dive-induced bubble formation. We postulate that exhaled NO concentration could be a useful index of decompression severity in healthy human divers.

Brain Damage in Commercial Breath-Hold Divers

Kiyotaka Kohshi, H Tamaki, F Lemaıtre, T Okudera, T Ishitake, PJ Denoble
PLoS ONE 9(8): e105006 http://dx.doi.org:/10.1371/journal.pone.0105006

Background: Acute decompression illness (DCI) involving the brain (Cerebral DCI) is one of the most serious forms of diving related injuries which may leave residual brain damage. Cerebral DCI occurs in compressed air and in breath-hold divers, likewise. We conducted this study to investigate whether long-term breath-hold divers who may be exposed to repeated symptomatic and asymptomatic brain injuries, show brain damage on magnetic resonance imaging (MRI).
Subjects and Methods: Our study subjects were 12 commercial breath-hold divers (Ama) with long histories of diving work in a district of Japan. We obtained information on their diving practices and the presence or absence of medical problems, especially DCI events. All participants were examined with MRI to determine the prevalence of brain lesions.
Results: Out of 12 Ama divers (mean age: 54.965.1 years), four had histories of cerebral DCI events, and 11 divers demonstrated ischemic lesions of the brain on MRI studies. The lesions were situated in the cortical and/or subcortical area (9 cases), white matters (4 cases), the basal ganglia (4 cases), and the thalamus (1 case). Subdural fluid collections were seen in 2 cases. Conclusion: These results suggest that commercial breath-hold divers are at a risk of clinical or subclinical brain injury which may affect the long-term neuropsychological health of divers.

Decompression illness

Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon
Lancet 2010; 377: 153–64

Decompression illness is caused by intravascular or extravascular bubbles that are formed as a result of reduction in environmental pressure (decompression). The term covers both arterial gas embolism, in which alveolar gas or venous gas emboli (via cardiac shunts or via pulmonary vessels) are introduced into the arterial circulation, and decompression sickness, which is caused by in-situ bubble formation from dissolved inert gas. Both syndromes can occur in divers, compressed air workers, aviators, and astronauts, but arterial gas embolism also arises from iatrogenic causes unrelated to decompression. Risk of decompression illness is
affected by immersion, exercise, and heat or cold. Manifestations range from itching and minor pain to neurological symptoms, cardiac collapse, and death. First aid treatment is 100% oxygen and definitive treatment is recompression to increased pressure, breathing 100% oxygen. Adjunctive treatment, including fluid administration and prophylaxis against venous thromboembolism in paralyzed patients, is also recommended. Treatment is, in most cases, effective although residual deficits can remain in serious cases, even after several recompressions.

Bubbles can have mechanical, embolic, and biochemical effects with manifestations ranging from trivial to fatal. Clinical manifestations can be caused by direct effects from extravascular (autochthonous) bubbles such as mechanical distortion of tissues causing pain, or vascular obstruction causing stroke-like signs and symptoms. Secondary effects can cause delayed symptom onset up to 24 h after surfacing. Endothelial damage by intravascular bubbles can cause capillary leak, extravasation of plasma, and haemoconcentration. Impaired endothelial function, as measured by decreased effects of vasoactive compounds, has been reported in animals and might occur in man. Hypotension can occur in severe cases. Other effects include platelet activation and deposition, leucocyte-endothelial adhesion, and possibly consequences of vascular occlusion believed to occur in thromboembolic stroke such as ischaemia-reperfusion injury, and apoptosis.

Classification of initial and of all eventual manifestations of decompression illness in 2346 recreational diving accidents reported to the Divers Alert Network from 1998 to 2004 For all instances of pain, 58% consisted of joint pain, 35% muscle pain, and 7% girdle pain. Girdle pain often portends spinal cord involvement. Constitutional symptoms included headache, lightheadedness, inappropriate fatigue, malaise, nausea or vomiting, and anorexia. Muscular discomfort included stiffness, pressure, cramps, and spasm but excluded pain. Pulmonary manifestations included dyspnoea and cough.

Other than depth and time, risk of decompression sickness is affected by other factors that affect inert gas exchange and bubble formation, such as immersion (vs dry hyperbaric chamber exposure), exercise, and temperature. Immersion decreases venous pooling and increases venous return and cardiac output. Warm environments improve peripheral perfusion by promoting vasodilation, whereas cool temperatures decrease perfusion through vasoconstriction. Exercise increases both peripheral perfusion and temperature. The effect of environmental conditions on risk of decompression sickness is dependent on the phase of the pressure exposure. Pressure, exercise, immersion, or a hot environment increase inert gas uptake and risk of decompression sickness. During decom-pression these factors increase inert gas elimination and therefore decrease the risk of decompression sickness. Conversely, uptake is reduced during rest or in a cold environment, hence a diver resting in a cold environment on the bottom has decreased risk of decompression sickness. Rest or low temperatures during decompression increase the risk. If exercise occurs after decompression when super-saturation is present, bubble formation increases and risk of decompression sickness rises.

Exercise at specific times before a dive can decrease the risk of serious decompression sickness in animals and incidence of venous gas emboli in both animals and man. The mechanisms of these effects are unknown but might involve modulation of nitric oxide production and effects on endothelium. Venous gas emboli and risk of decompression sickness increase slightly with age and body-mass index.

Arterial gas embolism should be suspected if a diver has a new onset of altered consciousness, confusion, focal cortical signs, or seizure during ascent or within a few minutes after surfacing from a compressed gas dive.

If the diver spends much time at depth and might have absorbed substantial inert gas before surfacing, arterial gas embolism and serious decompression sickness can coexist, and in such cases, spinal cord manifestations can predominate. Other organ systems, such as the heart, can also be affected, but the clinical diagnosis of gas embolism is not reliable without CNS manifestations. Arterial gas embolism is rare in altitude exposure; if cerebral symptoms occur after altitude exposure, the cause is usually decompression sickness.

Nondermatomal hypoaesthesia and truncal ataxia are common in neurological decompression sickness and can be missed by cursory examination. Pertinent information includes level of consciousness and mental status, cranial nerve function, and motor strength. Coordination can be affected disproportionately, and abnormalities can be detected by assessment of finger-nose movement, and, with eyes open and closed, ability to stand and walk and do heel-toe walking backwards and forwards. Many of these simple tests can be done on the scene by untrained companions.

Panel: Differential diagnosis of decompression illness

Inner-ear barotrauma

Middle-ear or maxillary sinus overinfl ation

Contaminated diving gas and oxygen toxic effects

Musculoskeletal strains or trauma sustained before, during, or after diving

Seafood toxin ingestion (ciguatera, pufferfish, paralytic shellfish poisoning)

Immersion pulmonary edema

Water aspiration

Decompression chamber

Decompression chamber. fluidic or pneumatic ventilator is shown at the left. The infusion pump is contained within a plastic cover, in which 100% nitrogen is used to decrease the fi re risk in the event of an electrical problem. The monitor screen is outside the chamber and can be seen through the viewing port. Photo from Duke University Medical Center, with permission.

Long-term outcomes of 69 divers with spinal cord decompressionsickness, by manifestation
	n	%
No residual symptoms	34	49·3
Any residual symptom	35	50·7
Mild paraesthesias, weakness, or pain	14	20·3
Some impairment of daily activities	21	30·4
Difficulty walking	11	15·9
Impaired micturition	13	18·8
Impaired defecation	15	21·7
Impaired sexual function	15	21·7

Decompression illness occurs in a small population but is an international problem that few physicians are trained to recognise or manage. Although its manifestations are often mild, the potential for permanent injury exists in severe cases, especially if unrecognised or inadequately treated. Emergency medical personnel should be aware of manifestations of decompression illness in the setting of a patient with a history of recent diving or other exposure to substantial pressure change, and should contact an appropriate consultation service for advice.

Diving Medicine: Contemporary Topics and Their Controversies

Michael B. Strauss and Robert C. Borer, Jr
Am J Emerg Med 2001; 19:232-238
http://dx.doi.org:/10.1053/ajem.2001.22654

SCUBA diving is a popular recreational sport. Although serious injuries occur infrequently, when they do knowledge of diving medicine and/or where to obtain appropriate consultation is essential. The emergency physician is likely to be the first physician contact the injured diver has. We discuss 8 subjects
in diving medicine which are contemporary, yet may have controversies associated with them. From this information the physician dealing primarily with the injured diver will have a basis for understanding and managing, as
well as where to find additional help, for his/her patients’ diving injuries.

Over the past 10 years, new knowledge and equipment improvements have made diving safer and more enjoyable. Estimates of actively participating sports divers show a striking increase over this time interval while the number of SCUBA diving deaths annually has remained nearly level at approximately 100. A further indicator of recreational diving safety is that reflected in the nearly constant number of diving injuries (1000 per annum) over the most recent 5 reported years, or approximately 0.53 to 3.4 incidents/10,000 dives.

Divers Alert Network.
The Divers Alert Network (DAN) is a nonprofit organization directed and staffed by experts in the specialty of diving medicine.6 DAN provides immediate consultation for both divers and physicians in the diagnosis and initial management of diving injuries. This 24-hour service is available free world-wide through a dedicated emergency telephone line: 1-919-684-4326. The DAN staff will also identify the nearest appropriate recompression treatment facility and knowledgeable physicians for an expedient referral. General diving medical inquiries can be answered during normal weekday hours either through an information telephone line: 1-919-684-2948 or through an interactive web site http://www.diversalertnetwork.org.

Use of 100% Oxygen for Initial, on the Scene, Management of Diving Accidents
The breathing of pure oxygen is crucial for the initial management of the diving related problems of arterial gas embolism (AGE), decompression sickness (DCS), pulmonary barotrauma (thoracic squeeze), aspiration pneumonitis, and hypoxic encephalopathy associated with near drowning. In 1985, Dick reported that in many cases the neurologic symptoms of AGE and DCS were resolved with the immediate breathing of pure oxygen on the surface. The breathing of pure oxygen reduces bubble size by increasing the differential pressure for the inert gas to diffuse out of the bubble and it also speeds the washout of inert gas from body tissues. The early elimination of the bubble prevents hypoxia and the interaction of the bubble with the blood vessel lining. This interaction leads to secondary problems of capillary leak, bleeding, inflammation, ischemia, and cell death. These secondary problems are the reasons not all DCS symptoms resolve with recompression chamber treatment. The immediate use of pure oxygen for the medical management of these diving problems is analogous to the use of cardiopulmonary resuscitation for the witnessed cardiac arrest; the sooner initiated the better the results.

Diving Education

Medical Fitness for Diving

Asthma has the potential risk for AGE. Neuman reviewed the subject of asthma and diving. He and his coauthors recommend that asthmatics who are asymptomatic, not on medications and have no exercised induced abnormality on pulmonary function studies be allowed to dive.

Conditions leading to loss of consciousness, such as insulin dependent diabetes and epilepsy, can result in drowning. Carefully controlled diving studies in diabetics, who are free from complications, are now defining the safe requirements for diving. Epilepsy remains as a disqualification except in individuals with a history of febrile seizures ending prior to 5 years of age.

Availability of Hyperbaric Oxygen Treatment Facilities

The availability of these chambers makes it possible for divers who become symptomatic after SCUBA diving to readily receive recompression treatment. This is important because the closer the initiation of recompression treatment to the onset of DCS (and AGE) signs and symptoms, the greater the likelihood of full recovery.

Improved Diving Equipment

Mixed and Rebreather Gas Diving
Mixed gas diving involves changing the breathing gas from air which has 20% oxygen to higher oxygen percentages (nitrox). As the amount of oxygen is increased in the gas mixture, the amount of the inert gas (nitrogen) is reduced. With oxygen enriched air there is less tissue deposition of inert gas per unit of time under water for any given depth. However, because of increased oxygen partial pressures, the seizure threshold for oxygen toxicity is lowered. For normal sports diving activities, oxygen toxicity with mixed gas diving is only a theoretical concern.

Decompression Illness is More Than Bubbles

When AGE occurs, DCS symptoms may be concurrent or appear during or after recompression treatment even though the decompression tables were not violated on the dive. When DCS occurs in this situation it appears resistant to recompression treatment (Neuman) perhaps because of the inflammatory reaction generated by the bubble-blood vessel interaction from the AGE. In cases of DCI where components of both DCS and AGE are suspected, the diver should be observed for a minimum of 24 hours after the recompression treatment is completed for the delayed onset of DCS.

No theory of DCS discounts the primary role of bubbles in this condition. However, new information suggests that there are precursors to bubble formation and post-bubbling events that occur as a consequence of the bubbles. As mentioned earlier, venous gas emboli are a common occurrence diving ascent and ordinarily are filtered out harmlessly by the lungs. Precursors to DCS include stasis, dehydration and too rapid of ascents. These conditions allow the ubiquitous VGE to enlarge, coalesce and occlude the venous side of the circulation. Massive venous bubbling to the lungs can cause pulmonary vessel obstruction described as the chokes. If right to left shunts occur in the heart, VGE can become AGE to the brain. If the arterial flow is slow enough and/or the gradients large enough, autochthonus (ie, spontaneous) bubbles can form in the arterial circulation and lead to any of the consequences of AGE. In such situations it could be difficult to determine whether the DCI event was from AGE or DCS even after careful analysis of the dive profile. Hollenbeck’s model for diving paraplegia includes the setting of venous stasis (Batson’s plexus of veins) in the spinal canal, bubble formation, bubble enlargement possibly from off gassing of the spinal cord, blood vessel occlusion, and venous side infarctions of the spinal cord.
Contemporary Management of DCS

Problem	Intervention	Effect
Bubble	Recompression with HBO	Reduce bubble size 1. Washout inert gas. 2. Change bubble composition by diffusion.
Stasis and dehydration	Hydration: oral fluids if alert, IV fluids otherwise.	Improve blood flow.
InflammationCell Ischemia	? Anti-inflammatory medicationsHBO	Reduce interaction between bubble and blood vessel endothelium. Improve oxygen availability to hypoxic tissues, reduce edema and also reduces the interaction between bubble and blood vessel endothelium.

Conclusions

We anticipate that in the future there will be further improvements for the safety and enjoyment of the recreational SCUBA diver. For example, the dive computer of the future will be able to individualize dive profiles for different personal medical parameters such as age, body composition and fitness level. Diver locators could quickly target a missing diver and save time and gas consumption as well as prevent serious diving mishaps. Drugs may be developed that would minimize the effect of bubbles interacting with body tissues and prevent DCS and AGE.

Extracorporeal membrane oxygenation therapy for pulmonary decompression illness

Yutaka Kondo, Masataka Fukami and Ichiro Kukita
Kondo et al. Critical Care 2014; 18:438 http://ccforum.com/content/18/3/438/10.1186/cc13935

Pulmonary decompression illness is rarely observed in clinical settings, and most patients die prior to hospitalization. We administered ECMO therapy to rescue a patient, even though this therapy has rarely been reported with good outcome in patients with decompression illness. In addition, we had to select venovenous ECMO even with the patient showing right ventricular failure. A lot of physicians may select venoarterial ECMO if the patient shows right ventricular failure, but the important physiological mechanism of pulmonary decompression illness is massive air embolism in the pulmonary arteries, and the bubbles diminish within the first 24 hours. The management of decompression illness therefore differs substantially from the usual right-sided heart failure.

Extremes of barometric pressure

Jane E Risdall, David P Gradwell
Anaesthesia and Intensive Care Medicine 16:2
Ascent to elevated altitude, commonly achieved through flight, by climbing or by residence in highland regions, exposes the individual to reduced ambient pressure. Although there are physical manifestations of this exposure as a consequence of Boyle’s law, the primary physiological challenge is of hypobaric hypoxia. The acute physiological and longer-term adaptive responses of the cardiovascular, respiratory, hematological and neurological systems to altitude are described, together with an outline of the presentation and management of acute mountain sickness, high-altitude pulmonary edema and high-altitude cerebral edema. While many millions experience modest exposure to altitude as a result of flight in pressurized aircraft, fewer individuals are exposed to increased ambient pressure. The pressure changes during diving and hyperbaric exposures result in greater changes in gas load and gas toxicity. Physiological effects include the consequences of increased work of breathing and redistribution of circulating volume. Neurological manifestations may be the direct result of pressure or a consequence of gas toxicity at depth. Increased tissue gas loads may result in decompression illness on return to surface or subsequent ascent in flight.

understand the physical effects of changes in ambient pressure and the physiological consequences on the cardiovascular respiratory and neurological systems
gain an awareness that exposure to reduced ambient pressure produces both acute and more chronic effects, with differing signs, symptoms and time to onset at various altitudes
develop an awareness of the toxic effects of ‘inert’ gases at increased ambient pressures and the pathogenesis and management of decompression illness

Decompression illness According to Henry’s law, at a constant temperature the amount of gas which dissolves in a liquid is proportional to the pressure of that gas or its partial pressure, if it is part of a mixture of gases. Breathing gases at increased ambient pressure will increase the amount of each gas dissolved in the fluid phases of body tissues. On ascent this excess gas has to be given up. If the ascent is controlled at a sufficiently slow rate, elimination will be via the respiratory system. If the ascent is too fast, excess gas may come out of solution and form free bubbles in the tissues or circulation. Bubbles may contain any of the gases in the breathing mixture, but it is the presence of inert gas bubbles (nitrogen or helium) that are thought most likely to give rise to problems, since the elimination of excess oxygen is achieved by metabolism as well as ventilation. These bubbles may act as venous emboli or may trigger inflammatory tissue responses giving rise to symptoms of decompression illness (DCI). Signs and symptoms of DCI may appear up to 48 hours after exposure to increased ambient pressure and include joint pains, motor and sensory deficits, dyspnoea, cough and skin rashes.

Neurological effects of deep diving

Marit Grønning, Johan A. Aarli
Journal of the Neurological Sciences 304 (2011) 17–21
http://dx.doi.org:/10.1016/j.jns.2011.01.021

Deep diving is defined as diving to depths more than 50 m of seawater (msw), and is mainly used for occupational and military purposes. A deep dive is characterized by the compression phase, the bottom time and the decompression phase. Neurological and neurophysiologic effects are demonstrated in divers during the compression phase and the bottom time. Immediate and transient neurological effects after deep dives have been shown in some divers. However, the results from the epidemiological studies regarding long term neurological effects from deep diving are conflicting and still not conclusive.

Possible immediate neurological effects of deep diving
Syndrome	Pressure
Hyperoxia/oxygen seizures	>152 kPa (5 msw)
HypoxiaHypercapnia
Nitrogen narcosis	>354 kPa (25 msw)
High pressure nervous syndrome	>1.6 MPa (150 msw)
Neurological decompression sickness

Neurological effects have been demonstrated, both clinically and neurophysiologically in divers during the compression phase and the bottom time. Studies of divers before and after deep dives have shown immediate and transient neurological effects in some divers. However, the results from the epidemiological and clinical studies regarding long term neurological effects from deep diving are conflicting and still not conclusive. Prospective clinical studies with sufficient power and sensitivity are needed to solve this important issue.

Today deep diving to more than 100 msw is routinely performed globally in the oil- and gas industry. In the North Sea remote underwater intervention and maintenance is performed by the use of remotely operated vehicles (ROV), both in conjunction to and as an alternative to manned underwater operations. There will, however, always be a need for human divers in the technically more advanced underwater operations and for contingency repair operations.

P300 latency indexes nitrogen narcosis

Barry Fowler, Janice Pogue and Gerry Porlier
Electroencephalography, and clinical Neurophysiology, 1990, 75:221-229

This experiment investigated the effects of nitrogen narcosis on reaction time (RT) and P300 latency and amplitude, Ten subjects breathed either air or a non-narcotic 20% oxygen-80% helium (heliox) mixture in a hyperbaric chamber at 6.5, 8.3 and 10 atmospheres absolute (ATA), The subjects responded under controlled accuracy conditions to visually presented male or female names in an oddball paradigm. Single-trial analysis revealed a strong relationship between RT and P300 latency, both of which were slowed in a dose-related manner by hyperbaric air but not by heliox. A clear-cut dose-response relationship could not be established for P300 amplitude. These results indicate that P300 latency indexes nitrogen narcosis and are interpreted as support for the slowed processing model of inert gas narcosis.

Adaptation to Deep Water Habitat

Effects of hypoxia on ionic regulation, glycogen utilization and antioxidative ability in the gills and liver of the aquatic air-breathing fish Trichogaster microlepis

Chun-Yen Huang, Hui-Chen Lina, Cheng-Huang Lin
Comparative Biochemistry and Physiology, Part A 179 (2015) 25–34
http://dx.doi.org/10.1016/j.cbpa.2014.09.001

We examined the hypothesis that Trichogaster microlepis, a fish with an accessory air-breathing organ, uses a compensatory strategy involving changes in both behavior and protein levels to enhance its gas exchange ability. This compensatory strategy enables the gill ion-regulatory metabolism to maintain homeostasis during exposure to hypoxia. The present study aimed to determinewhether ionic regulation, glycogen utilization and antioxidant activity differ in terms of expression under hypoxic stresses; fish were sampled after being subjected to 3 or 12 h of hypoxia and 12 h of recovery under normoxia. The air-breathing behavior of the fish increased under hypoxia. No morphological modification of the gills was observed. The expression of carbonic anhydrase II did not vary among the treatments. The Na+/K+-ATPase enzyme activity did not decrease, but increases in Na+/K+-ATPase protein expression and ionocyte levels were observed. The glycogen utilization increased under hypoxia as measured by glycogen phosphorylase protein expression and blood glucose level, whereas the glycogen content decreased. The enzyme activity of several components of the antioxidant system in the gills, including catalase, glutathione peroxidase, and superoxidase dismutase, increased in enzyme activity. Based on the above data, we concluded that T. microlepis is a hypoxia-tolerant species that does not exhibit ion-regulatory suppression but uses glycogen to maintain energy utilization in the gills under hypoxic stress. Components of the antioxidant system showed increased expression under the applied experimental treatments.

Divergence date estimation and a comprehensive molecular tree of extant cetaceans

Michael R. McGowen , Michelle Spaulding, John Gatesy
Molecular Phylogenetics and Evolution 53 (2009) 891–906
http://dx.doi.org/10.1016/j.ympev.2009.08.018

Cetaceans are remarkable among mammals for their numerous adaptations to an entirely aquatic existence, yet many aspects of their phylogeny remain unresolved. Here we merged 37 new sequences from the nuclear genes RAG1 and PRM1 with most published molecular data for the group (45 nuclear loci, transposons, mitochondrial genomes), and generated a supermatrix consisting of 42,335 characters. The great majority of these data have never been combined. Model-based analyses of the supermatrix produced a solid, consistent phylogenetic hypothesis for 87 cetacean species. Bayesian analyses corroborated odontocete (toothed whale) monophyly, stabilized basal odontocete relationships, and completely resolved branching events within Mysticeti (baleen whales) as well as the problematic speciose clade Delphinidae (oceanic dolphins). Only limited conflicts relative to maximum likelihood results were recorded, and discrepancies found in parsimony trees were very weakly supported. We utilized the Bayesian supermatrix tree to estimate divergence dates among lineages using relaxed-clock methods. Divergence estimates revealed rapid branching of basal odontocete lineages near the Eocene–Oligocene boundary, the antiquity of river dolphin lineages, a Late Miocene radiation of balaenopteroid mysticetes, and a recent rapid radiation of Delphinidae beginning [1]10 million years ago. Our comprehensive, time calibrated tree provides a powerful evolutionary tool for broad-scale comparative studies of Cetacea.

Mitogenomic analyses provide new insights into cetacean origin and evolution

Ulfur Arnason, Anette Gullberg, Axel Janke
Gene 333 (2004) 27–34
http://dx.doi.org:/10.1016/j.gene.2004.02.010

The evolution of the order Cetacea (whales, dolphins, porpoises) has, for a long time, attracted the attention of evolutionary biologists. Here we examine cetacean phylogenetic relationships on the basis of analyses of complete mitochondrial genomes that represent all extant cetacean families. The results suggest that the ancestors of recent cetaceans had an explosive evolutionary radiation 30–35 million years before present. During this period, extant cetaceans divided into the two primary groups, Mysticeti (baleen whales) and Odontoceti (toothed whales). Soon after this basal split, the Odontoceti diverged into the four extant lineages, sperm whales, beaked whales, Indian river dolphins and delphinoids (iniid river dolphins, narwhals/belugas, porpoises and true dolphins). The current data set has allowed test of two recent morphological hypotheses on cetacean origin. One of these hypotheses posits that Artiodactyla and Cetacea originated from the extinct group Mesonychia, and the other that Mesonychia/Cetacea constitutes a sister group to Artiodactyla. The current results are inconsistent with both these hypotheses. The findings suggest that the claimed morphological similarities between Mesonychia and Cetacea are the result of evolutionary convergence rather than common ancestry.

The order Cetacea traditionally includes three suborders: the extinct Archaeoceti and the recent Odontoceti and Mysticeti. It is commonly believed that the evolution of ancestral cetaceans from terrestrial to marine (aquatic) life was accompanied by a fast and radical morphological adaptation. Such a scenario may explain why it was, for a long time, difficult to morphologically establish the position of Cetacea in the mammalian tree and even to settle whether Cetacea constituted a monophyletic group.

Biochemical analyses in the 1950s and 1960s had shown a closer relationship between cetaceans and artiodactyls (even-toed hoofed mammals) than between cetaceans and any other eutherian order and karyological studies in the late 1960s and early 1970s unequivocally supported cetacean monophyly (Arnason, 1969, 1974). The nature of the relationship between cetaceans and artiodactyls was resolved in phylogenetic studies of mitochondrial (mt) cytochrome b (cytb) genes (Irwin and Arnason, 1994; Arnason and Gullberg, 1996) that placed Cetacea within the order Artiodactyla itself as the sister group of the Hippopotamidae (see also Sarich, 1993). The Hippopotamidae/ Cetacea relationship was subsequently supported in studies of nuclear data (Gatesy et al., 1996; Gatesy, 1997) and statistically established in analysis of complete mt genomes (Ursing and Arnason, 1998). The relationship has also been confirmed in analyses of combined nuclear and mt sequences (Gatesy et al., 1999; Cassens et al., 2000) and in studies of short interspersed repetitive elements (SINEs). Artiodactyla and Cetacea are now commonly referred to as Cetartiodactyla.

Previous analyses of the complete cytb gene of more than 30 cetacean species (Arnason and Gullberg, 1996) identified five primary lineages of recent cetaceans, viz., Mysticeti and the four odontocete lineages Physeteridae (sperm whales), Platanistidae (Indian river dolphins), Ziphiidae (beaked whales) and Delphinoidea (iniid river dolphins, porpoises, narwhals and dolphins). However, these studies left unresolved the relationships of the five lineages as well as those between the three delphinoid families Monodontidae (narwhals, belugas), Phocoenidae (porpoises) and Delphinidae (dolphins). Similarly, the relationships between the four mysticete families Balaenidae (right whales), Neobalaenidae (pygmy right whales), Eschrichtiidae (gray whales) and Balaenopteridae (rorquals) were not conclusively resolved in analyses of cytb genes.

Fig. (not shown). Cetartiodactyl relationships and the estimated times of their divergences. The tree was established on the basis of maximum likelihood analysis of the concatenated amino acid (aa) sequences of 12 mt protein-coding genes. Length of alignment 3610 aa. Support values for branches A–H are shown in the insert.
Cetruminantia (branch A) receives moderate support and Cetancodonta (B) strong support. Cetacea (C) splits into monophyletic Mysticeti (baleen whales) and monophyletic Odontoceti (toothed whales). Odontoceti has four basal lineages, Physeteridae (sperm whales: represented by the sperm and pygmy sperm whales), Ziphiidae (beaked whales: bottlenose and Baird’s beaked whales), Platanistidae (Indian river dolphins: Indian river dolphin) and Delphinoidea. Delphinoidea encompasses the families Iniidae (iniid river dolphins: Amazon river dolphin, La Plata dolphin), Monodontidae (narwhals/belugas: narwhal), Phocoenidae (porpoises: harbour porpoise) and Delphinidae (dolphins: white-beaked dolphin). The common odontocete branch and the branches separating the four cetacean lineages are short. These relationships are therefore somewhat unstable (cf. Section 3.1 and Table 1). Iniid river dolphins (F) are solidly nested within the Delphinoidea (E). Thus, traditional river dolphins (Platanistidae + Iniidae) do not form a monophyletic unit. Molecular estimates of divergence times (Sanderson 2002) were based on two calibration points, A/C-60 and O/M-35 (cf. Section 3.2). Due to the short lengths of internal branches, some estimates for these divergences overlap. NJ: neighbor joining; MP: maximum parsimony; LBP: local bootstrap probability; QP: quartet puzzling. The bar shows the number of aa substitutions per site.

The limited molecular resolution among basal cetacean lineages has been known for some time. Studies of hemoglobin and myoglobin (Goodman, 1989; Czelusniak et al., 1990) have either joined Physeteridae and Mysticeti to the exclusion of Delphinoidea (myoglobin data) or Mysticeti and Delphinoidea to the exclusion of Physeteridae (hemoglobin data). Thus, neither of the data sets identified monophyletic Odontoceti by joining the two odontocete lineages (Physeteridae and Delphinoidea) to the exclusion of Mysticeti. A similar instability was recognized and cautioned against in analyses of some mt data, notably, sequences of rRNA genes (Arnason et al., 1993b). The suggestion (Milinkovitch et al., 1993) of a sister group relationship between Physeteridae and the mysticete family Balaenopteridae (rorquals) was based on a myoglobin data set (which joins Physeteridae and Mysticeti to the exclusion of Delphinoidea) that was complemented with partial data of the mt 16S rRNA gene.

The cetancodont divergence times calculated using A/C-60 and O/M-35 as references have been included in Fig. 1. As a result of the short branches separating several cetacean lineages, the estimates of these divergences overlap. The same observation has been made in calculations based on SINE flanking sequences (Nikaido et al., 2001). There is a general consistency between the current and the flanking sequence datings, except for those involving the Balaenopteridae, which are somewhat younger in our analysis than in the SINEs study. The currently estimated age of the divergence between Hippopotamus and Cetacea (c53.5 MYBP) is consistent with the age (>50 MY) of the oldest archaeocete fossils identified so far (Bajpai and Gingerich, 1998). This suggests that the ages allocated to the two references, A/C-60 (the divergence between ruminant artiodactyls and cetancodonts) and O/M-35 (the divergence between odontocetes and mysticetes) are reasonably accurate.

The dating of the divergence between the blue and fin whales is of interest regarding hybridization between closely related mammalian species. Previous molecular analyses (Arnason et al., 1991b; Spilliaert et al., 1991) demonstrated the occurrence of hybridization between these two species. These studies, which were based on three hybrids (one female and two males), showed that either species could be the mother or father in these hybridizations. The two male hybrids had rudimentary testes, whereas the female hybrid was in her second pregnancy. This suggests that the blue and fin whales may be close to the limit for permissible species hybridization among mammals.

The current data set has allowed examination of the coherence between the molecular results and two prevalent morphological hypotheses related to cetacean evolution. The first hypothesis, which in essence originates from Van Valen (1966, 1968), postulates that monophyletic Artiodactyla and monophyletic Cetacea evolved separately from the extinct Palaeocene group Mesonychia. This hypothesis was recently reinforced in a morphological study (Thewissen et al., 2001) that included mesonychians, two archaeocete taxa (Ambuloocetus and Pakicetus) and some extant and fossil artiodactyls. The study of Thewissen et al. (2001) showed a sister group relationship between monophyletic Artiodactyla and monophyletic Cetacea, with Mesonychia as the basal sister group of Artiodactyla/Cetacea, a conclusion consistent with the palaeontological age of Mesonychia relative to that of Artiodactyla and Cetacea. The second hypothesis favours a sister group relationship between Mesonychia and Cetacea with the Mesonychia/Cetacea clade as the sister group of monophyletic Artiodactyla (O’Leary and Geisler, 1999; see also Gatesy and O’Leary, 2001).

Although the position of Mesonychia differs in the two morphological hypotheses, both correspond to a sister group relationship between Cetacea and monophyletic Artiodactyla among extant cetartiodactyls. Thus, both hypotheses can be tested against the current data set. The result of such a test has been included in Table 1, topology (m)(not shown). As evident, both these morphological hypotheses are incongruent with the mitogenomic findings.

Morphological studies have not provided an answer to the question whether mysticetes and odontocetes had separate origins among the archaeocetes (Fordyce and de Muizon, 2001). However, the long common cetacean branch and the short branches separating the five extant cetacean lineages strongly suggest an origin of modern cetaceans from the same archaeocete group (probably the Dorudontidae).

The limbs of Ambulocetus constitute somewhat of an evolutionary enigma. As evident in Thewissen et al.’s (1994) paper, Ambulocetus has very large hind limbs compared to its forelimbs, a difference that is less pronounced in later silhouette drawings of the animal. It is nevertheless evident that evolution from the powerful hindlimbs of Ambulocetus to their rudimentation in archaeocetes constitutes a remarkable morphological reversal if Ambulocetus is connected to the cetacean branch after the separation of the hippopotamid and cetacean lineages.

For natural reasons, systematic schemes have traditionally been based on external morphological characteristics. The rates of morphological and molecular evolution are rarely (if ever) strictly correlated, however, and this may give rise to inconsistency between traditional systematics and molecular findings. The emerging consensus that the order Cetacea resides within another traditional order, Artiodactyla, makes apparent the incongruity in cetartiodactyl nomenclature (Graur and Higgins, 1994). In this instance, a possible solution for maintaining reasonable consistency between nomenclature and phylogeny would be to recognize Cetartiodactyla as an order with three suborders: Suina, Tylopoda and Cetruminantia. According to such a scheme, Cetacea would (together with the Hippopotamidae) constitute a parvorder within the infraorder Cetancodonta.

Cytochrome b and Bayesian inference of whale phylogeny

Laura May-Collado, Ingi Agnarsson
Molecular Phylogenetics and Evolution 38 (2006) 344–354
http://dx.doi.org//10.1016/j.ympev.2005.09.019

In the mid 1990s cytochrome b and other mitochondrial DNA data reinvigorated cetacean phylogenetics by proposing many novel

and provocative hypotheses of cetacean relationships. These results sparked a revision and reanalysis of morphological datasets, and the collection of new nuclear DNA data from numerous loci. Some of the most controversial mitochondrial hypotheses have now become benchmark clades, corroborated with nuclear DNA and morphological data; others have been resolved in favor of more traditional views. That major conflicts in cetacean phylogeny are disappearing is encouraging. However, most recent papers aim specifically to resolve higher-level conflicts by adding characters, at the cost of densely sampling taxa to resolve lower-level relationships. No molecular study to date has included more than 33 cetaceans. More detailed molecular phylogenies will provide better tools for evolutionary studies. Until more genes are available for a high number of taxa, can we rely on readily available single gene mitochondrial data? Here, we estimate the phylogeny of 66 cetacean taxa and 24 outgroups based on Cytb sequences. We judge the reliability of our phylogeny based on the recovery of several deep-level benchmark clades. A Bayesian phylogenetic analysis recovered all benchmark clades and for the Wrst time supported Odontoceti monophyly based exclusively on analysis of a single mitochondrial gene. The results recover the monophyly, with the exception of only one taxa within Cetacea, and the most recently proposed super- and subfamilies. In contrast, parsimony never recovered all benchmark clades and was sensitive to a priori weighting decisions. These results provide the most detailed phylogeny of Cetacea to date and highlight the utility of both Bayesian methodology in general, and of Cytb in cetacean phylogenetics. They furthermore suggest that dense taxon sampling, like dense character sampling, can overcome problems in phylogenetic reconstruction.

Some long standing debates are all but resolved: our understanding of deeper level cetacean phylogeny has grown strong. However, the strong focus of most recent studies, aiming specifically to resolve these higher level conflicts by adding mostly characters rather than taxa, has left our understanding of lower level relationships among whale species lagging behind. Mitogenomic data, for example, is available only for 16 cetacean species, and no molecular study to date has included more than 33 cetaceans. It seems timely to focus on more detailed (genus, and species level) molecular phylogenies. These will provide better tools for detailed evolutionary studies, and are necessary to test existing morphological phylogenetic hypotheses, and current cetacean classification.

We judge the reliability of our phylogeny based on the recovery of the previously mentioned benchmark clades, in addition to the less controversial clades Perissodactyla, Euungulata (sensu Waddell et al., 2001; Perissodactyla+ Cetartiodactyla), Cetacea, and Mysticeti. Because Cytb is thought to be most reliable at lower taxonomic levels (due to high substitution rates), recovering ‘known’ deeper clades gives credibility to these new findings which have not been addressed by studies using few taxa. We compare the performance of Bayesian analyses versus parsimony under four different models, and briefly examine the sensitivity of the results to taxon sampling. We use our results to discuss agreement and remaining conflict in cetacean phylogenetics, and provide comments on current classification.

The Bayesian analysis recovered all seven benchmark clades. Support for five of the benchmark clades is high (100 posterior probabilities) but rather low for Cetancodonta (79) and marginal for the monophyly of Odontoceti. The analysis also recovered all but one family level, and most sub- and superfamily level cetacean taxa. The results broadly corroborate current cetacean classiffcation, while also pointing to some lower-level groups that may need redefinition.

Many recent cetacean phylogenetic studies include relatively few taxa, in part due to a focus on generating more characters to resolve higher level phylogenetics. While addressing crucial questions and providing the backbone for lower level phylogenies, such studies have limited utility for classification, and for comparative evolutionary studies. In some cases sparse taxon sampling may also confound the results. Of course, taxon sampling is usually simply constrained by the availability of character data, but for some reason many studies have opted to include only one, or a few outgroup taxa, even if many are available.

We find that as long as outgroup taxon sampling was extensive, Bayesian analyses of Cytb recovered all the a priori identified benchmark clades. When only a few outgroups were chosen, however, the Bayesian analysis negated Odontoceti monophyly, as have many previous parsimony analyses of mitochondrial DNA. Furthermore, in almost every detailed comparison possible our results mirror the findings O’Leary et al. (2004), the most ‘character-complete’ (but including relatively few cetacean taxa) analysis to date (37,000 characters from morphology, SINE, and 51 gene fragments). This result gives credibility to our findings, including previously untested lower level clades.

Monophyly and placement of Mysticeti (baleen whales).
Monophyly of Odontoceti (toothed whales)
Delphinoids
River Dolphins
Beaked and sperm whales

A major goal of phylogenetics is a phylogeny of life (i.e., many taxa), based on multiple lines of evidence (many characters of many types). However, when phylogenies based on relatively few characters can be judged reliable based on external evidence (taxonomic congruence with other phylogenies using many characters, but few taxa), they seem like very promising and useful ‘first guess’ hypotheses. The evolution of sexual dimorphism, echolocation, social behavior, and whistles and other communicative signals, and major ecological shifts (e.g., transition to fresh water) are among the numerous interesting questions in cetacean biology that this phylogeny can help answer.

Deep-diving sea lions exhibit extreme bradycardia in long duration dives

Birgitte I. McDonald1, and Paul J. Ponganis
The Journal of Experimental Biology (2014) 217, 1525-1534 http://dx.doi.org:/10.1242/jeb.098558

Heart rate and peripheral blood flow distribution are the primary determinants of the rate and pattern of oxygen store utilization and ultimately breath-hold duration in marine endotherms. Despite this, little is known about how otariids (sea lions and fur seals) regulate heart rate (fH) while diving. We investigated dive fH in five adult female California sea lions (Zalophus californianus) during foraging trips by instrumenting them with digital electrocardiogram (ECG) loggers and time depth recorders. In all dives, dive fH (number of beats/duration; 50±9 beats min⁻¹) decreased compared with surface rates (113±5 beats min⁻¹), with all dives exhibiting an instantaneous fH below resting (<54 beats min⁻¹) at some point during the dive. Both dive fH and minimum instantaneous fH significantly decreased with increasing dive duration. Typical instantaneous fH profiles of deep dives (>100 m) consisted of:

(1) an initial rapid decline in fH resulting in the lowest instantaneous fH of the dive at the end of descent, often below 10 beats min⁻¹ in dives longer than 6 min in duration;
(2) a slight increase in fH to ~10–40 beats min⁻¹ during the bottom portion of the dive; and
(3) a gradual increase in fH during ascent with a rapid increase prior to surfacing.

Thus, fH regulation in deep-diving sea lions is not simply a progressive bradycardia. Extreme bradycardia and the presumed associated reductions in pulmonary and peripheral blood flow during late descent of deep dives should

(a) contribute to preservation of the lung oxygen store,
(b) increase dependence of muscle on the myoglobin-bound oxygen store,
(c) conserve the blood oxygen store and
(d) help limit the absorption of nitrogen at depth.

This fH profile during deep dives of sea lions may be characteristic of deep-diving marine endotherms that dive on inspiration as similar fH profiles have been recently documented in the emperor penguin, another deep diver that dives on inspiration.

The resting ƒH measured in this study (54±6 beats min⁻¹) was lower than predicted for an animal of similar size (~80 beats min⁻¹ for an 80 kg mammal). In part, this may be due to the fact that the sea lions were probably sleeping. The resting ƒH in our study was also lower than previous measurements in captive juvenile California sea lions (87±17 beats min⁻¹, average mass 30 kg) and wild Antarctic fur seals (78±5 beats min⁻¹, body mass 30–50 kg). However, we found a significant negative relationship between mass and resting ƒH even with our small sample size of five sea lions (resting ƒH = –0.58 Mb +100.26, r²=0.81, F_1,3=12.37, P=0.039). For a 30 kg sea lion, this equation predicts a resting ƒH of 83 beats min⁻¹, which is similar to what was measured previously in juvenile sea lions, suggesting this equation may be useful in estimating resting ƒH in sea lions.

The sea lions exhibited a distinct sinus arrhythmia fluctuating between a minimum of 42±9 and a maximum of 87±12 beats min⁻¹, comparable to the sinus arrhythmias described in other diving birds and mammals, including sea lions. The minimum instantaneous ƒH during the sinus arrhythmia was similar to the mean minimum ƒH in dives less than 3 min (37±7 beats min⁻¹), indicating that in dives less than 3 min (estimated cADL), ƒH only decreased to levels observed during exhalation at rest. This is consistent with observations in emperor penguins and elephant seals, where it was proposed that in dives shorter than the aerobic dive limit (ADL) the reduction in ƒH is regulated by a mechanism of cardiorespiratory control similar to that governing the respiratory sinus arrhythmia, with a further reduction only occurring in dives longer than the ADL.

Fig. 3. (not shown) Instantaneous fH and dive depth profiles of a California sea lion (CSL12_2). Data are from (A) a short, shallow dive (1.3 min, 45 m), (B) a mid-duration dive (4.8 min, 239 m) and (C) a long-duration dive (8.5 min, 305 m). Minimum instantaneous fH reached 37 beats min⁻¹ in the short dive
(A) 19 beats min⁻¹ in the mid-duration dive
(B) and 7 beats min⁻¹ in the long duration dive
(C) Prominent features typical of mid- and long-duration dives include

a surface interval tachycardia (pre- and post-dive);
a steady rapid decrease in fH during initial descent;
a gradual decline in fH towards the end of descent with the lowest fH of the dive at the end of descent;
a slight increase and sometimes variable fH during the bottom portion of the dive; and
a slow increase in fH during ascent,
often ending in a rapid increase just before surfacing.

We obtained the first diving ƒH data from wild sea lions on natural foraging trips, demonstrating how they regulate ƒH over a range of dive durations. Sea lions always decreased dive ƒH from surface ƒH values; however, individual sea lions exhibited different dive ƒH, accounting for a significant amount of the variation in the relationship between dive duration and ƒH (intra-individual correlation: 75–81%)). The individual differences in dive ƒH exhibited in this study suggest that different dive capacities of individual sea lions may partially account for the range of dive strategies exhibited in a previous study (Villegas-Amtmann et al., 2011). Despite the individual differences in ƒH, the pattern of the dive ƒH response was similar in all the sea lions. As predicted, sea lions only consistently displayed a true bradycardia on mid- to long- duration dives (>4 min) (Fig. 5A). Additionally, as seen in freely diving phocids, dive ƒH and minimum ƒH were negatively related to dive duration, with the longest duration dives having the lowest dive ƒH and displaying the most intense bradycardia, often below 10 beats min⁻¹ (Fig. 5A,B).

Profiles of mean fH at 10 s intervals of dives

Fig 4. Profiles of mean fH at 10 s intervals of dives for (A) six duration categories and (B) five depth categories. Standard error bars are shown. Data were pooled from 461 dives performed by five sea lions. The number of dives in each category and the number of sea lions performing the dives in each category are provided in the keys.

The mild bradycardia and the dive ƒH profiles observed in the shorter duration dives (<3 min) were similar to those observed in trained juvenile California sea lions and adult Stellar sea lions, but much more intense than ƒH observed in freely diving Antarctic fur seals. Surprisingly, although dive ƒH of trained Steller sea lions was similar, Steller sea lions regularly exhibited lower minimum ƒH, with minimum ƒH almost always less than 20 beats min⁻¹ in dives less than 2 min in duration. In the wild, California sea lions rarely exhibited a minimum ƒH less than 20 beats min⁻¹ in similar duration dives (Fig. 5B), suggesting greater blood oxygen transport during these natural short-duration dives.

Fig. 5. (not shown) fH decreases with increasing dive duration. Dive duration versus (A) dive fH (total number of beats/dive duration), (B) minimum instantaneous fH and (C) bottom fH (total beats at bottom of dive/bottom time) for California sea lions (461 dives from five sea lions).

Although California sea lions are not usually considered exceptional divers, they exhibited extreme bradycardia, comparable to that of the best diving phocids, during their deep dives. In dives greater than 6 min in duration, minimum ƒH was usually less than 10 beats min⁻¹ and sometimes as low as 6 beats mins⁻¹ (Fig. 5B), which is similar to extreme divers such as emperor penguins (3 beats min−1), elephant seals (3 beats min⁻¹), grey seals (2 beats min−1) and Weddell seals (<10 beats min⁻¹), and even as low as what was observed in forced submersion studies. Thus, similar to phocids, the extreme bradycardia exhibited during forced submersions is also a routine component of the sea lion’s physiological repertoire, allowing them to perform long-duration dives.

While the degree of bradycardia observed in long dives of California sea lions was similar to the extreme bradycardia observed in phocids, the ƒH profiles were quite different. In general, phocid ƒH decreases abruptly upon submergence. The intensity of the initial phocid bradycardia either remains relatively stable or intensifies as the dive progresses, and does not start to increase until the seal begins its ascent. In contrast, the ƒH profiles of sea lions were more complex, showing a more gradual decrease during descent, with the minimum ƒH of the dive usually towards the end of descent (Figs 3, 6). There was often a slight increase in ƒH during the bottom portion of the dive, and as soon as the sea lions started to ascend, the ƒH slowly started to increase, often becoming irregular during the middle of ascent, before increasing rapidly as the sea lion approached the surface.

Fig. 6. (not shown) Instantaneous fH and dive depth profiles of the longest dive (10.0 min, 385 m) from a California sea lion (CSL12_1). During this dive, instantaneous fH reached 7 beats min⁻¹ and was less than 20 beats min⁻¹ for over 5.5 min. Post-dive fH was high in the first 0.5–1 min after surfacing, but then declined to ~100 beats min⁻¹ towards the end of the surface interval.

Implications for pulmonary gas exchange

The moderate dive ƒH in short, shallow dives compared with the much slower ƒH of deep long-duration dives suggests more pulmonary blood flow and greater potential for reliance on lung O2. Most of these dives were to depths of less than 100 m (well below the estimated depth of lung collapse near 200 m), so maintenance of a moderate ƒH during these dives may allow sea lions to maximise use of the potentially significant lung O2 stores (~16% of total body O2 stores) throughout the dive. This is supported by venous blood O2 profiles, where, occasionally, there was no decrease in venous blood O2 between the beginning and end of the dive; this can only occur if pulmonary gas exchange continues throughout the dive. Greater utilization of the lung O2 store in sea lions is consistent with higher dive ƒH in other species that both dive on inspiration and typically perform shallow dives (dolphins, porpoises, some penguin species), and in deeper diving species when they perform shallow dives (emperor penguins).

In deeper dives of sea lions, although ƒH was lower and bradycardia more extreme, the diving ƒH profiles suggest that pulmonary gas exchange is also important. In long-duration dives, even though ƒH started to decrease upon or shortly after submergence, the decrease was not as abrupt as in phocids. Additionally, in long deep dives, despite having overall low dive ƒH, there were more heart beats before resting ƒH was reached compared with short, shallow dives. In dives less than 3 min in duration, there were ~10–15 beats until instantaneous ƒH reached resting values. In longer duration dives (>3 min), there were usually ~30–40 beats before instantaneous ƒH reached resting values. We suggest the greater number of heart beats early in these deeper dives enables more gas exchange and blood O2 uptake at shallow depths, thus allowing utilisation of the postulated larger respiratory O2 stores in deeper dives The less abrupt decline in ƒH we observed in sea lions is similar to the more gradual declines documented in emperor penguins and porpoises, where it has also been proposed that the gradual decrease in ƒH allows them to maximise pulmonary gas exchange at shallower depths. However, as sea lions swam deeper, ƒH decreased further (Figs 3, 6), and by 200 m depth (the approximate depth of lung collapse, instantaneous ƒH was 14 beats min⁻¹. Such an extreme decline in ƒH in conjunction with increased pulmonary shunting due to lung compression at greater depths will result in minimization of both O2 and N2 uptake by blood, even before the depth of full lung collapse (100% pulmonary shunt) is reached.

Implications for blood flow

ƒH is often used as a proxy to estimate blood flow and perfusion during diving because of the relative ease of its measurement. This is based on the assumption that stroke volume does not change during diving in sea lions, and, hence, changes in ƒH directly reflect changes in cardiac output. As breath-hold divers maintain arterial pressure while diving, changes in cardiac output should be associated with changes in peripheral vascular resistance and changes in blood flow to tissues. In Weddell seals, a decrease in cardiac output of ~85% during forced submersions resulted in an 80–100% decrease in tissue perfusion in all tissues excluding the brain, adrenal glands and lung. Sea lions exhibited extremely low instantaneous ƒH values that often remained low for significant portions of the dive (Figs 4, 6), suggesting severe decreases in tissue perfusion in dives greater than 5 min in duration. In almost all dives greater than 6 min in duration, instantaneous ƒH reached 10 beats min⁻¹, and stayed below 20 beats min⁻¹ for more than a minute. At a ƒH of 20 beats min⁻¹, cardiac output will be ~36% of resting cardiac output and only about 18% of average surface cardiac output. At these levels of cardiac suppression, most of this flow should be directed towards the brain and heart.

Conclusions

We successfully obtained diving ƒH profiles from a deep-diving otariid during natural foraging trips. We found that

(1) ƒH decreases during all dives, but true and more intense bradycardia only occurred in longer duration dives and
(2) in the longest duration dives, ƒH and presumed cardiac output were as low as 20% of resting values.

We conclude that, although initial high ƒH promotes gas exchange early in deep dives, the extremely low ƒH in late descent of deep dives (a) preserves lung O2, (b) conserves blood O2, (c) increases the dependence of muscle on myoglobin-bound O2 and (d) limits N2 absorption at depth. This ƒH profile, especially during the late descent/early bottom phase of deep dives is similar to that of deep-diving emperor penguins, and may be characteristic of deep diving endotherms that dive on inspiration.

Dive duration was the fixed effect in all models, and to account for the lack of independence caused by having many dives from the same individual, individual (sea lion ID) was included as a random effect. Covariance and random effect structures of the full models were evaluated using Akaike’s information criterion (AIC) and examination of residual plots. AICs from all the tested models are presented with the best model in bold.

Additionally, dives were classified as short-duration (less than 3 min, minimum cADL), mid-duration (3–5 min, range of cADLs) or long-duration (>5 min) dives. Differences in pre-dive ƒH, dive ƒH, minimum ƒH, post-dive ƒH, and heart beats to resting between the categories were investigated using mixed effects ANOVA, followed by post hoc Tukey tests. In all models, dive duration category was the fixed effect and individual (sea lion ID) was included as a random effect. Model fit was accessed by examination of the residuals. All means are expressed ±s.d. and results of the Tukey tests were considered significant at P<0.05. Statistical analysis was performed in R.

Investigating Annual Diving Behaviour by Hooded Seals (Cystophora cristata) within the Northwest Atlantic Ocean

Julie M. Andersen, Mette Skern-Mauritzen, Lars Boehme
PLoS ONE 8(11): e80438. http://dx.doi.org:/10.1371/journal.pone.0080438

With the exception of relatively brief periods when they reproduce and molt, hooded seals, Cystophora cristata, spend most of the year in the open ocean where they undergo feeding migrations to either recover or prepare for the next fasting period. Valuable insights into habitat use and diving behavior during these periods have been obtained by attaching Satellite Relay Data Loggers (SRDLs) to 51 Northwest (NW) Atlantic hooded seals (33 females and 18 males) during icebound fasting periods (200422008). Using General Additive Models (GAMs) we describe habitat use in terms of First Passage Time (FPT) and analyze how bathymetry, seasonality and FPT influence the hooded seals’ diving behavior described by maximum dive depth, dive duration and surface duration. Adult NW Atlantic hooded seals exhibit a change in diving activity in areas where they spend .20 h by increasing maximum dive depth, dive duration and surface duration, indicating a restricted search behavior. We found that male and female hooded seals are spatially segregated and that diving behavior varies between sexes in relation to habitat properties and seasonality. Migration periods are described by increased dive duration for both sexes with a peak in May, October and January. Males demonstrated an increase in dive depth and dive duration towards May (post-breeding/pre-molt) and August–October (post-molt/pre-breeding) but did not show any pronounced increase in surface duration. Females dived deepest and had the highest surface duration between December and January (post-molt/pre-breeding). Our results suggest that the smaller females may have a greater need to recover from dives than that of the larger males. Horizontal segregation could have evolved as a result of a resource partitioning strategy to avoid sexual competition or that the energy requirements of males and females are different due to different energy expenditure during fasting periods.

Novel locomotor muscle design in extreme deep-diving whales

P. Velten, R. M. Dillaman, S. T. Kinsey, W. A. McLellan and D. A. Pabst
The Journal of Experimental Biology 216, 1862-1871
http://dx.doi.org:/10.1242/jeb.081323

Most marine mammals are hypothesized to routinely dive within their aerobic dive limit (ADL). Mammals that regularly perform deep, long-duration dives have locomotor muscles with elevated myoglobin concentrations that are composed of predominantly large, slow-twitch (Type I) fibers with low mitochondrial volume densities (Vmt). These features contribute to extending ADL by increasing oxygen stores and decreasing metabolic rate. Recent tagging studies, however, have challenged the view that two groups of extreme deep-diving cetaceans dive within their ADLs. Beaked whales (including Ziphius cavirostris and Mesoplodon densirostris) routinely perform the deepest and longest average dives of any air-breathing vertebrate, and short-finned pilot whales (Globicephala macrorhynchus) perform high-speed sprints at depth. We investigated the locomotor muscle morphology and estimated total body oxygen stores of several species within these two groups of cetaceans to determine whether they

(1) shared muscle design features with other deep divers and
(2) performed dives within their calculated ADLs.

Muscle of both cetaceans displayed high myoglobin concentrations and large fibers, as predicted, but novel fiber profiles for diving mammals. Beaked whales possessed a sprinterʼs fiber-type profile, composed of ~80% fast-twitch (Type II) fibers with low Vmt. Approximately one-third of the muscle fibers of short-finned pilot whales were slow-twitch, oxidative, glycolytic fibers, a rare fiber type for any mammal. The muscle morphology of beaked whales likely decreases the energetic cost of diving, while that of short-finned pilot whales supports high activity events. Calculated ADLs indicate that, at low metabolic rates, both beaked and short-finned pilot whales carry sufficient onboard oxygen to aerobically support their dives.

Serial cross-sections of the m. longissimus dorsi of Mesoplodon densirostris

Fig. Serial cross-sections of the m. longissimus dorsi of Mesoplodon densirostris (A–D) and Globicephala macrorhynchus (E–H). Scale bars, 50μm. Muscle sections stained for the alkaline (A,E) and acidic (B,F) preincubations of myosin ATPase were used to distinguish Type I and II fibers. Muscle sections stained for succinate dehydrogenase (C,G) and α-glycerophosphate dehydrogenase (D,H) were used to distinguish glycolytic (gl), oxidative (o) and intermediate (i) fibers.

Previous studies of the locomotor muscles of deep-diving marine mammals have demonstrated that these species share a suite of adaptations that increase onboard oxygen stores while slowing the rate at which these stores are utilized, thus extending ADL. Their locomotor muscles display elevated myoglobin concentrations and are composed predominantly of large Type I fibers. Vmt are also lower in deep divers than in shallow divers or athletic terrestrial species. The results of this study indicate that beaked whales and short-finned pilot whales do not uniformly display these characteristics and that each possesses a novel fiber profile compared with those of other deep divers.

The phylogeny of Cetartiodactyla: The importance of dense taxon sampling, missing data, and the remarkable promise of cytochrome b to provide reliable species-level phylogenies

Ingi Agnarsson, Laura J. May-Collado
Molecular Phylogenetics and Evolution 48 (2008) 964–985
http://dx.doi.org:/10.1016/j.ympev.2008.05.046

We perform Bayesian phylogenetic analyses on cytochrome b sequences from 264 of the 290 extant cetartiodactyl mammals (whales plus even-toed ungulates) and two recently extinct species, the ‘Mouse Goat’ and the ‘Irish Elk’. Previous primary analyses have included only a small portion of the species diversity within Cetartiodactyla, while a complete supertree analysis lacks resolution and branch lengths limiting its utility for comparative studies. The benefits of using a single-gene approach include rapid phylogenetic estimates for a large number of species. However, single-gene phylogenies often differ dramatically from studies involving multiple datasets suggesting that they often are unreliable. However, based on recovery of benchmark clades—clades supported in prior studies based on multiple independent datasets—and recovery of undisputed traditional taxonomic groups, Cytb performs extraordinarily well in resolving cetartiodactyl phylogeny when taxon sampling is dense. Missing data, however, (taxa with partial sequences) can compromise phylogenetic accuracy, suggesting a tradeoff between the benefits of adding taxa and introducing question marks. In the full data, a few species with a short sequences appear misplaced, however, sequence length alone seems a poor predictor of this phenomenon as other taxa.

The mammalian superorder Cetartiodactyla (whales and eventoed ungulates) contains nearly 300 species including many of immense commercial importance (cow, pig, and sheep) and of conservation interest and aesthetic value (antelopes, deer, giraffe, dolphins, and whales) (MacDonald, 2006). Certain members of this superorder count among the best studied organisms on earth, whether speaking morphologically, behaviorally, physiologically or genetically. Understanding the interrelationships among cetartiodactyl species, therefore, is of obvious importance with equally short sequences were not conspicuously misplaced. Although we recommend awaiting a better supported phylogeny based on more character data to reconsider classification and taxonomy within Cetartiodactyla, the new phylogenetic hypotheses provided here represent the currently best available tool for comparative species-level studies within this group. Cytb has been sequenced for a large percentage of mammals and appears to be a reliable phylogenetic marker as long as taxon sampling is dense. Therefore, an opportunity exists now to reconstruct detailed phylogenies of most of the major mammalian clades to rapidly provide much needed tools for species-level comparative studies.

Our results support the following relationship among the four major cetartiodactylan lineages (((Tylopoda ((Cetancodonta (Ruminantia + Suina))), with variable support. This arrangement has not been suggested previously, to our knowledge (see review in O’Leary and Gatesy, 2008 and discussion).

Relationships among clades within Cetancodonta are identical to those found by May-Collado and Agnarsson (2006).

Within Ruminantia all our analyzes suggest the following relationships among families: (((((Tragulidae((((Antilocapridae(((Giraffidae(( Cervidae(Moschidae + Bovidae))))) with relatively high support, supporting the subdivision of Ruminantia into Tragulina and Pecora.
In the rare cases where our results are inconsistent with benchmark clades, ad hoc explanations seem reasonable. The placement of M. meminna (Tragulidae) within Bovidae is likely an artifact of missing data, although remarkably it is the only conspicuous misplacement of a species across the whole phylogeny at the family level (while three species appear to be misplaced at the subfamily level within Cervidae in the full analysis, see Fig. 5a). This is supported by the fact that the placement of Moschiola receives low support, and the removal of Moschiola prior to analysis increases dramatically the support for clades close to where it nested (not shown, analysis available from authors), suggesting it had a tendency to ‘jump around’. Two other possibilities cannot be ruled out, however. One, that possibly the available sequence in Genbank may be mislabeled. And second, it should be kept in mind that the validity of Tragulidae has never been tested with molecular data including more than two species.

Oxygen and carbon dioxide fluctuations in burrows of subterranean blind mole rats indicate tolerance to hypoxic–hypercapnic stresses

Imad Shams, Aaron Avivi, Eviatar Nevo
Comparative Biochemistry and Physiology, Part A 142 (2005) 376 – 382
http://dx.doi.org:/10.1016/j.cbpa.2005.09.003

The composition of oxygen (O2), carbon dioxide (CO2), and soil humidity in the underground burrows from three species of the Israeli subterranean mole rat Spalax ehrenbergi superspecies were studied in their natural habitat. Two geographically close populations of each species from contrasting soil types were probed. Maximal CO2 levels (6.1%) and minimal O2 levels (7.2%) were recorded in northern Israel in the breeding mounds of S. carmeli in a flooded, poor drained field of heavy clay soil with very high volumetric water content. The patterns of gas fluctuations during the measurement period among the different Spalax species studied were similar. The more significant differentiation in gas levels was not among species, but between neighboring populations inhabiting heavy soils or light soils: O2 was lower and CO2 was higher in the heavy soils (clay and basaltic) compared to the relatively light soils (terra rossa and rendzina). The extreme values of gas concentration, which occurred during the rainy season, seemed to fluctuate with partial flooding of the tunnels, animal digging activity, and over-crowded breeding mounds inhabited by a nursing female and her offspring. The gas composition and soil water content in neighboring sites with different soil types indicated large differences in the levels of hypoxic–hypercapnic stress in different populations of the same species. A growing number of genes associated with hypoxic stress have been shown to exhibit structural and functional differences between the subterranean Spalax and the aboveground rat (Rattus norvegicus), probably reflecting the molecular adaptations that Spalax went through during 40 million years of evolution to survive efficiently in the severe fluctuations in gas composition in the underground habitat.

map of the studied sites

Schematic map of the studied sites: S. galili (2n =52): 1— Rehania (chalk); 2— Dalton (basaltic); S. golani (2n =54): 3— Majdal Shams (terra tossa); 4—Masa’ada (basaltic soils); S. carmeli (2n =58): 5— Al-Maker (heavy clay); 6— Muhraqa (terra rossa).

Comparison of gas composition (O2 and CO2) and water content between light and heavy soils inhabited by S. carmeli

Comparison of gas composition (O2 and CO2) and water content between light and heavy soils inhabited by S. carmeli, Al-Maker (heavy soil) and Muhraqa (light soil). AverageTSD of measurements in the burrows of approximately 10 animals at a given date is presented. **p <0.01, T-test and Mann– Whitney test).

Subterranean mammals, which live in closed underground burrow systems, experience an atmosphere that is different from the atmosphere above-ground. Gas exchange between these two atmospheres depends on diffusion through the soil, which in turn, depends on soil particle size, water content, and burrow depth. Heavy soils (clay and basaltic), hold water and have little air space for gas diffusion. A large deviation from external gas composition is found in the burrows of Spalax living in these soil types. The maximal measured concentration of CO2 was 6.1% in Spalax breeding mounds, which is one of the highest concentrations among studied mammals in natural conditions. At the same time 7.2% O2 was measured in water saturated heavy clay soil

seasonal variation from August to March in mean O2, CO2, and soil water content

Example of seasonal variation from August to March in mean O2, CO2, and soil water content (VWC) in the Al-Maker population (2n =58, heavy soil). Values are presented as mean TSD.

In this study new data were presented for a wild mammal that survives in an extreme hypoxic–hypercapnic environment. Interestingly, the very low concentrations of O2 experienced by Spalax are correlated with the expression pattern of hypoxia related genes. So far, we have shown higher and longer-term mRNA expression of erythropoietin, the main factor that regulates the level of circulating red blood cells, in subterranean Spalax compared to the above-ground rat in response to hypoxic stress, as well as differences in the response of erythropoietin to hypoxia in different populations of Spalax experiencing different hypoxic stress in nature. We also demonstrated that erythropoietin pattern of expression is different in Spalax than in Rattus throughout development, a pattern suggesting more efficient hypoxic tolerance in Spalax starting as early as in the embryonic stages. Furthermore, vascular endothelial growth factor (VEGF), which is a critical angiogenic factor that responds to hypoxia, is constitutively expressed at maximal levels in Spalax muscles, the most energy consuming tissue during digging. This level is 1.6-fold higher than in Rattus muscles and is correlated with significantly higher blood vessel concentration in the Spalax muscles compared to the Rattus muscles. Likewise, myoglobin the globin involved in oxygen homeostasis in skeletal muscles, exhibits different expression pattern under normoxia and in response to hypoxia in Spalax muscles compared to rat muscles as well as between different populations of Spalax exposed to different hypoxic stress in nature (unpublished results). Similarly, neuroglobin, a brain-specific globin involved in reversible oxygen binding, i.e., presumably in cellular homeostasis, is expressed differently in the Spalax brain compared to Rattus brain. Like erythropoietin and myoglobin also neuroglobin is expressed differently in Spalax populations experiencing different oxygen supply (unpublished results). Furthermore, Spalax p53 harbors two amino acid substitutions in its binding domain, which are identical to mutations found in p53 of human cancer cells. These substitutions endow Spalax p53 with several-fold higher activation of cell arrest and DNA repair genes compared to human p53 and favor activation of DNA repair genes over apoptotic genes. The study of specific tumoral variants indicates that such preference of growth arrest over apoptosis possibly results as a response to the hypoxic environmental stress known in tumors. Differences in the structure of other molecules related to homeostasis, namely, hemoglobin, haptoglobin (Nevo, 1999), and cytoglobin (unpublished) were also observed in Spalax.

Stress, adaptation, and speciation in the evolution of the blind mole rat, Spalax, in Israel

Eviatar Nevo
Molecular Phylogenetics and Evolution 66 (2013) 515–525
http://dx.doi.org/10.1016/j.ympev.2012.09.008

Environmental stress played a major role in the evolution of the blind mole rat superspecies Spalax ehrenbergi, affecting its adaptive evolution and ecological speciation underground. Spalax is safeguarded all of its life underground from aboveground climatic fluctuations and predators. However, it encounters multiple stresses in its underground burrows including darkness, energetics, hypoxia, hypercapnia, food scarcity, and pathogenicity. Consequently, it evolved adaptive genomic, proteomic, and phenomic complexes to cope with those stresses. Here I describe some of these adaptive complexes, and their theoretical and applied perspectives. Spalax mosaic molecular and organismal evolution involves reductions or regressions coupled with expansions or progressions caused by evolutionary tinkering and natural genetic engineering. Speciation of Spalax in Israel occurred in the Pleistocene, during the last 2.00–2.35 Mya, generating four species associated intimately with four climatic regimes with increasing aridity stress southwards and eastwards representing an ecological speciational adaptive trend: (Spalax golani, 2n = 54?S. galili, 2n = 52?S. carmeli, 2n = 58?S. judaei, 2n = 60). Darwinian ecological speciation occurred gradually with relatively little genetic change by Robertsonian chromosomal and genic mutations. Spalax genome sequencing has just been completed. It involves multiple adaptive complexes to life underground and is an evolutionary model to a few hundred underground mammals. It involves great promise in the future for medicine, space flight, and deep-sea diving.

Stress is a major driving force of evolution (Parsons, 2005; Nevo, 2011). Parsons defined stress as the ‘‘environmental factor causing potential injurious changes to biological systems with a potential for impacts on evolutionary processes’’. The global climatic transition from the middle Eocene to the early Oligocene (45–35 Ma = Million years ago) led to extensive convergent evolution underground of small subterranean mammals across the planet (Nevo, 1999; Lacey et al., 2000; Bennett and Faulkes, 2000; Begall et al., 2007). The subterranean ecotope provided small mammals with shelter from predators and extreme aboveground climatic stressful fluctuations of temperature and humidity. However, they had to evolve genomic adaptive complexes for the immense underground stresses of darkness, energy for burrowing in solid soil, low productivity and food scarcity, hypoxia, hypercapnia, and high infectivity. These stresses have been described in Nevo (1999, 2011) and Nevo et al. (2001); and Nevo list of Spalax publication at http://evolution.haifa.ac.il with many cited references relevant to these stresses).

blind subterranean mole rat of the Spalax ehrenbergi superspecies

The blind subterranean mole rat of the Spalax ehrenbergi superspecies in Israel. An extreme example of adaptation to life underground

Circadian rhythm and genes

adaptive circadian genes. We identified the circadian rhythm of Spalax
(Nevo et al., 1982) and described, cloned, sequenced, and expressed several circadian genes in Spalax. These include Clock, MOP3, three Period (Per), and cryptochromes (Avivi et al., 2001, 2002, 2003). The Spalax circadian genes are differentially conserved, yet characterized by a significant number of amino acid substitutions. The glutamine-rich area of Clock, which is assumed to function in circadian rhythmicity, is expanded in Spalax compared with that of mice and humans and is different in amino acid composition from that of rats. All three Per genes of Spalax oscillate with a periodicity of 24 h in the suprachaismatic nucleus, eye, and Harderian gland and are expressed in peripheral organs. Per genes are involved in clock resetting. Spalax Per 3 is unique in mammals though its function is still unresolved. The Spalax Per genes contribute to the unique adaptive circadian rhythm to life underground. The cryptochrome (Cry) genes, found in animals and plants, act both as photoreceptors and as ingredients of the negative feedback mechanism of the biological Clock. The CRY 1 protein is significantly closer to the human homolog than to that of mice, as was also shown in parts of the immunogenetic system. Both Cry 1 and Cry 2 mRNAs were found in the SCN, eye, harderian gland, and in peripheral tissues. Remarkably, the distinctly hypertrophied harderian gland is central in Spalax’s unique underground circadian rhythmicity (Pevet et al., 1984).

Spalax eye mosaic evolution
Gene expression in the eye of Spalax
Brain evolution in Spalax to underground stresses
Spalax: four species in Israel

The morphological, physiological, and behavioral Spalax eye patterns are underlain by gene expression representing regressive and progressive associated transcripts. Regressive transcripts involve B-2 microglobulin, transketolase, four keratins, alpha enolase, and different heat shock proteins. Several proteins may be involved in eye degeneration. These include heat shock protein 90alpha (hsp90alpha), found also in the blind fish Astyanax mexicanus, two transcripts of programmed cell death proteins, oculospanin, and peripherin 2, both belonging to the Tetraspanin family, in which 60 different mutations cause eye degeneration in humans. Several progressive transcripts in the Spalax eye are found in the retina of many mammals involving gluthatione, peroxidase 4, B spectrin, and Ankyrin; the last two characterize rod cells in the retina. Some transcripts are involved in metabolic processing of retinal, a vertebrate key component in phototransduction, and a relative of vitamin A.

cross section of the developing eye of the mole rat

Light micrographs showing cross section of the developing eye of the mole rat Spalax ehrenbergi. (A) Optic cup and lens vesicle initially develop normally (x100). (B) Eye at a later embryonic stage. Note appearance of iris-ciliary body rudiment (arrows), and development of the lens nucleus (L). ON, optic nerve (x100). (C) Eye at a still later fetal stage. Note massive growth of the iris-ciliary body complex colobomatous opening (arrow) (x100). (D) Early postnatal stage. The iris-ciliary body complex completely fills the chamber. The lens is vascularized and vacuolated (x100). (E) Adult eye. Eyelids are completely closed and pupil is absent. Note atrophic appearance of the optic disc region (arrow) (x65). (F) Higher magnification of the adult retina. The different retinal layers are retained: PE, pigment epithelium: RE, receptor layer; ON, outer nuclear layer: IN, inner nuclear layer; GC, ganglion cell layer (x500) (from Sanyal et al., 1990, Fig. 1).

The brains of subterranean mammals underwent dramatic evolution in accordance with underground stresses for digging and photoperiodic perception associated with vibrational, tactile, vocal, olfactory, and magnetic communication systems replacing sight, as is seen in Spalax. The brain of Spalax is twice as large as that of the laboratory rat of the same body size. The somatosensory region in the isocortex of Spalax is 1.7 times, the thalamic nuclei 1.3 times, and the motor cortex 3.1 times larger than in the sighted laboratory rat Rattus norvegicus matched to body size.

The ecological stress determinant in Spalax brain evolution is highlighted by the four species of the Spalax ehrenbergi superspecies in Israel. They differentiated chromosomally (by means of Robertsonian mutations and fission), allopatrically, and clinally southwards into four species associated with different climatic regimes, following the gradient of increasing aridity stress and decreasing predictability southwards towards the desert: Spalax galili (2n = 52) ->S. golani (2n = 54)->S. carmeli (2n = 58)->S. judaei (2n = 60), and eastwards S. galili ->S. golani (2n = 52–>54) (Fig. 2). This chromosomal speciation trend southwards is associated with the regional aridity stress southwards (and eastwards) in Israel, budding new species adapted genomically, proteomically, and phenomically (i.e., in morphology, physiology, and behavior) to increasing stresses of higher solar radiation, temperature, and drought southwards (Nevo, 1999; Nevo et al., 2001; Nevo
list of Spalax at http://evolution.haifa.ac.il). A uniquely recent discovery of incipient sympatric ecological speciation at a microscale in Spalax triggered by local stresses occurs within Spalax galili.

retinal input to primary visual structures in Spalax

Relative degree of retinal input to primary visual structures in Spalax, hamster, rat, and Spalacopus cyanus (South American Octodontidae, ‘‘coruro’’). These rodents are of similar body size (120–140 g). B. Relative degree of change in the proportions of retinal input to different primary visual structures in Spalax compared with measures obtained in other rodents. A relative progressive development in Spalax is seen in structures involved in photoperiodic and neuroendocrine functions (SCN, BNST).The main regressive feature is the drastic relative reduction of retinal input to the superior colliculus. The main regressive feature is the drastic reduction of retinal input to the superior colliculus. The relative size of other visual structures in Spalax is modified compared to that of the other species. c. Comparison of the absolute size (volume, mm³ x 10^-4) of visual structures in Spalax and other rodents. The size of the SCN is equivalent in all species. The vLGN and dLGN are reduced by 87–93% in Spalax. The retino-recipient layers of the superior colliculus are reduced by 97%. Abbreviations: SCN: suprachiasmatic nucleus; BNST: bed nucleus of the stria terminalis; dLGN: dorsal lateral geniculate nucleus; SC: superior colliculus [From Cooper et al., 1993 (Fig 3)].

Subterranean life has a high energetic cost if an animal has to burrow in order to obtain its food. For a 150 g Thomomys bottae, burrowing 1 m may be 360–3400 times more expensive energetically than moving the same distance on the surface (Vleck, 1979). Mean rates of oxygen consumption during burrowing at 22 ^oC are from 2.8 to 7.1 times the RMR. Vleck developed a model examining the energetics of foraging by burrowing and found that, in the desert, Thomomys adjusts the burrow segment length to minimize the cost of burrowing. Since burrowing becomes less economic as body size increases, Vleck (1981) predicted that the maximum possible body size that a subterranean mammal can attain depends on a balance between habitat productivity and the cost of burrowing in local soils. Vleck’s cost of burrowing hypothesis has been verified in multiple cases. Heth (1989) demonstrated longer burrows in the rendzina soil and shorter ones in the terra rossa soil, associating lower productivity in the former for Spalax.

Food is a limiting factor for subterranean mammals. The abundance and distribution of food explain some of the ecological, physiological, and behavioral characteristics of subterranean mammals. In a field test of Spalax foraging strategy, we concluded that Spalax was a generalist due to the constraints of the subterranean ecotope. Restricted foraging time primarily during the winter when soil is wet, and the high energetic investment of tunneling to get to food items is significantly reduced than in summertime.
We also identified a decrease in the basic metabolic rate towards the desert, i.e., economizing energetics. The maintenance of adequate O2 transport in a subterranean mammal confronting hypoxia requires adaptation along the O2 transport system, achieved by increasing the flow of O2 in the convection systems (ventilation and perfusion) and by reduction of oxygen pressure (PO2) gradients at the diffusion barriers (lung blood, blood-tissue (Arieli, 1990). The PO2 gradient between blood capillaries and respiring mitochondria capillaries is large, and any adaptation at this level could be significant for O2 transport. Reduction of diffusion distance in a muscle can be achieved, like in Spalax, by increasing the number of capillaries that surround muscle fiber or by reducing fiber areas.

Geographic distribution in Israel of the four chromosomal species belonging to the S. ehrenbergi superspecies

Geographic distribution in Israel of the four chromosomal species belonging to the S. ehrenbergi superspecies that are separated by narrow hybrid zones (2n = 52, 54, 58, and 60, now named as S. galili, S. golani, S. carmeli, and S. judaei, respectively; see Nevo et al., 2001).

Spalacid evolution, based on mtDNA, is driven by climatic oscillations and stresses. The underground ecotope provided subterranean mammals with shelter from extreme climate (temperature and humidity) fluctuations, and predators. However, they had to extensively and intensively adapt to the multiple underground stresses (darkness, energetic, low productivity and
food scarcity, hypoxia, hypercapnia, and high infectivity). All subterranean mammals, including spalacids as an extreme case, share convergent molecular and organismal adaptations to their shared unique underground ecotope. Evolution underground, as exemplified here in spalacids, led to mosaic molecular and organismal evolutionary syndromes to cope with multiple stresses.

Speciation involves all rates – from gradual to rapid. Subterranean mammals, with the spalacid example discussed above, provide uniquely rich evolutionary global tests of speciation and adaptation, convergence, regression, progression, and mosaic evolutionary processes. Adaptation and speciation underground was one of the most dramatic natural experiments verifying Darwinian evolution.

The Spalax genome sequencing has just been completed. It is being analyzed and will soon be published in 2012. This will be a milestone in understanding how numerous mammals across the globe, who found underground shelter from climatic fluctuations and stresses above ground, cope with the new suite of stresses they encountered underground, demanding a new engineering overhaul on all organizational levels, selecting for adaptive complexes to cope with the new underground stresses. The main current and future challenges are to compare and contrast genome sequences and identify the genomic basis of adaptation and speciation.

This global Cenozoic experiment could answer the following open questions: How heterozygous is the whole genome? How prevalent are retrotransposons and what is their functional role? How many genes are involved in the Spalax genome and how are they regulated? What are the genic and regulatory networks resisting the multiple stresses underground? How much of the Spalax genome is conserved and how much is reorganized to cope with the underground stresses? How is the solitary blind mole rat, Spalax, different from the social naked mole rat Heterocephalus? How are the processes of reduction, expansion, and genetic tinkering and engineering reflected across the genome? How effective is copy number variation in regulation? Is there similarity in the transcriptomes of subterranean mammals? How could we harness the rich genome repertoire of Spalax to revolutionize medicine, especially in the realm of hypoxia tolerance and the related major diseases of the western world, e.g., cancer, stroke, and cardiovascular diseases? What is the phylogenetic origin of Spalax? How much of the Spalax genome represents its phylogenetic roots and how much of coding and noncoding genomic regions are shared with other subterranean mammals across the globe in adapting to life underground?

The Atmospheric Environment of the Fossorial Mole Rat (Spalax Ehrenbergi): Effects of Season, Soil Texture, Rain, Temperature and Activity

Arieli
Comp Biochen Physiol. 1978; 63A:569-5151. The fossorial mole rat (Spalax ehrenbergi) may inhabit heavy soil with low gas permeability.
Air composition in burrows in heavy soil deviates from atmospheric air more than that of burrows in light soil.
In winter and spring O2 and CO2 concentrations in breeding mounds were 16.5% O2 and 2.5-3x CO2 and the extreme values measured were 14.0% O2 and 4.8% Cot.
Hypoxia and hypercapnia in the burrow develop shortly after rain and when ambient temperature drops.
Composition of the burrows air is influenced by the solubility of CO2 in soil water and by faster penetration of oxygen than outflowing of CO2.

Hypo-osmotic stress-induced physiological and ion-osmoregulatory responses in European sea bass (Dicentrarchus labrax) are modulated differentially by nutritional status

Amit Kumar Sinha, AF Dasan, R Rasoloniriana, N Pipralia, R Blust, G De Boeck
Comparative Biochemistry and Physiology, Part A 181 (2015) 87–99
http://dx.doi.org/10.1016/j.cbpa.2014.11.024

We investigated the impact of nutritional status on the physiological, metabolic and ion-osmoregulatory performance of European sea bass (Dicentrarchus labrax)when acclimated to seawater (32 ppt), brackishwater (20 and 10 ppt) and hyposaline water (2.5 ppt) for 2 weeks. Following acclimation to different salinities, fish were either fed or fasted (unfed for 14 days). Plasma osmolality, [Na+], [Cl−] and muscle water contentwere severely altered in fasted fish acclimated to 10 and 2.5 ppt in comparison to normal seawater-acclimated fish, suggesting ion regulation and acid–base balance disturbances. In contrast to feed-deprived fish, fed fish were able to avoid osmotic perturbation more effectively. This was accompanied by an increase in Na+/K+-ATPase expression and activity, transitory activation of H+-ATPase (only at 2.5 ppt) and down-regulation of Na+/K+/2Cl− gene expression. Ammonia excretion rate was inhibited to a larger extent in fasted fish acclimated to low salinities while fed fish were able to excrete efficiently. Consequently, the build-up of ammonia in the plasma of fed fish was relatively lower. Energy stores, especially glycogen and lipid, dropped in the fasted fish at low salinities and progression towards the anaerobic metabolic pathway became evident by an increase in plasma lactate level. Overall, the results indicate no osmotic stress in both feeding treatments within the salinity range of 32 to 20 ppt. However, at lower salinities (10–2.5 ppt) feed deprivation tends to reduce physiological, metabolic, ion-osmo-regulatory and molecular compensatory mechanisms and thus limits the fish’s abilities to adapt to a hypo-osmotic environment.

The absence of ion-regulatory suppression in the gills of the aquatic air-breathing fish Trichogaster lalius during oxygen stress

Chun-Yen Huang, Hsueh-Hsi Lin, Cheng-Huang Lin, Hui-Chen Lin
Comparative Biochemistry and Physiology, Part A 179 (2015) 7–16
http://dx.doi.org/10.1016/j.cbpa.2014.08.017

The strategy for most teleost to survive in hypoxic or anoxic conditions is to conserve energy expenditure, which can be achieved by suppressing energy-consuming activities such as ion regulation. However, an air-breathing fish can cope with hypoxic stress using a similar adjustment or by enhancing gas exchange ability, both behaviorally and physiologically. This study examined Trichogaster lalius, an air-breathing fish without apparent gill modification, for their gill ion-regulatory abilities and glycogen utilization under a hypoxic treatment. We recorded air-breathing frequency, branchial morphology, and the expression of ion-regulatory proteins (Na+/K+-ATPase and vacuolar-type H+-ATPase) in the 1st and 4th gills and labyrinth organ (LO), and the expression of glycogen utilization (GP, glycogen phosphorylase protein expression and glycogen content) and other protein responses (catalase, CAT; carbonic anhydrase II, CAII; heat shock protein 70, HSP70; hypoxia-inducible factor-1α, HIF-1α; proliferating cell nuclear antigen, PCNA; superoxidase dismutase, SOD) in the gills of T. lalius after 3 days in hypoxic and restricted conditions. No morphological modification of the 1st and 4th gills was observed. The air breathing behavior of the fish and CAII protein expression both increased under hypoxia. Ion-regulatory abilities were not suppressed in the hypoxic or restricted groups, but glycogen utilization was enhanced within the groups. The expression of HIF-1α, HSP70 and PCNA did not vary among the treatments. Regarding the antioxidant system, decreased CAT enzyme activity was observed among the groups. In conclusion, during hypoxic stress, T. lalius did not significantly reduce energy consumption but enhanced gas exchange ability and glycogen expenditure.

The combined effect of hypoxia and nutritional status on metabolic and ionoregulatory responses of common carp (Cyprinus carpio)

Sofie Moyson, HJ Liew, M Diricx, AK Sinha, R Blusta, G De Boeck
Comparative Biochemistry and Physiology, Part A 179 (2015) 133–143
http://dx.doi.org/10.1016/j.cbpa.2014.09.017

In the present study, the combined effects of hypoxia and nutritional status were examined in common carp (Cyprinus carpio), a relatively hypoxia tolerant cyprinid. Fish were either fed or fasted and were exposed to hypoxia (1.5–1.8mgO2 L−1) at or slightly above their critical oxygen concentration during 1, 3 or 7 days followed by a 7 day recovery period. Ventilation initially increased during hypoxia, but fasted fish had lower ventilation frequencies than fed fish. In fed fish, ventilation returned to control levels during hypoxia, while in fasted fish recovery only occurred after reoxygenation. Due to this, C. carpio managed, at least in part, to maintain aerobic metabolism during hypoxia: muscle and plasma lactate levels remained relatively stable although they tended to be higher in fed fish (despite higher ventilation rates). However, during recovery, compensatory responses differed greatly between both feeding regimes: plasma lactate in fed fish increased with a simultaneous breakdown of liver glycogen indicating increased energy use, while fasted fish seemed to economize energy and recycle decreasing plasma lactate levels into increasing liver glycogen levels. Protein was used under both feeding regimes during hypoxia and subsequent recovery: protein levels reduced mainly in liver for fed fish and in muscle for fasted fish. Overall, nutritional status had a greater impact on energy reserves than the lack of oxygen with a lower hepatosomatic index and lower glycogen stores in fasted fish. Fasted fish transiently increased Na+/K+-ATPase activity under hypoxia, but in general ionoregulatory balance proved to be only slightly disturbed, showing that sufficient energy was left for ion regulation.

The effect of temperature and body size on metabolic scope of activity in juvenile Atlantic cod Gadus morhua L.

Bjørn Tirsgaard, Jane W. Behrens, John F. Steffensen
Comparative Biochemistry and Physiology, Part A 179 (2015) 89–94
http://dx.doi.org/10.1016/j.cbpa.2014.09.033

Changes in ambient temperature affect the physiology and metabolism and thus the distribution of fish. In this study we used intermittent flow respirometry to determine the effect of temperature (2, 5, 10, 15 and 20 °C) and wet body mass (BM) (~30–460 g) on standard metabolic rate (SMR, mg O2 h−1), maximum metabolic rate (MMR, mg O2 h−1) and metabolic scope (MS, mg O2 h−1) of juvenile Atlantic cod. SMR increased with BM irrespectively of temperature, resulting in an average scaling exponent of 0.87 (0.82–0.92). Q10 values were 1.8–2.1 at temperatures between 5 and 15 °C but higher (2.6–4.3) between 2 and 5 °C and lower (1.6–1.4) between 15 and 20 °C in 200 and 450 g cod. MMR increased with temperature in the smallest cod (50 g) but in the larger cod MMR plateaued between 10, 15 and 20 °C. This resulted in a negative correlation between the optimal temperature for MS (T_opt) and BM, T_opt being respectively 14.5, 11.8 and 10.9 °C in a 50, 200 and 450 g cod. Irrespective of BM cold water temperatures resulted in a reduction (30–35%) of MS whereas the reduction of MS at warm temperatures was only evident for larger fish (200 and 450 g), caused by plateauing of MMR at 10 °C and above. Warm temperatures thus seem favorable for smaller (50 g) juvenile cod, but not for larger conspecifics (200 and 450 g).

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Altitude Adaptation

Posted in Amino acids, Biochemical pathways, Biological Networks, Ca2+ triggered activation, Cardiovascular Research, Cell Biology, Curation, Developmental biology, Enzymes and isoenzymes, Fatty acids, Gene Regulation and Evolution, Hematology, Hematopoiesis, Lipid metabolism, Liver & Digestive Diseases Research, Metabolism, Mutant Gene Expression, Myocardial Metabolism, Nitric Oxide in Health and Disease, Proteins, Proteomics, Signaling, Signaling & Cell Circuits, tagged acute high altitude sickness, altitude adaptation, Andeas, cewrebral edema, chronic altitude sickness, cognitive effects, Evolution, hemoglobin gene substitutions, hemoglobins, high elevation plants, Himalayan Plateau, mammals, mountain antelope, Mountain sickness, pulmonary edema, Tibetan goat, Tibetan sheep on February 24, 2015| Leave a Comment »

Altitude Adaptation

Writer and Curator: Larry H. Bernstein, MD, FCAP

Introduction

Land adapted animals depend on respiration for oxygen supply, but have adapted to altitudes that have difference oxygen contents. In this discussion we explore how animals have adapted to oxygen supply in different terrestrial habitats, and also how humans adjust to short term changes in high and extreme altitudes.

High-altitude adaptation is an evolutionary modification in animals, most notably in birds and mammals, by which species are subjected to considerable physiological changes to survive in extremely high mountainous environments. As opposed to short-term adaptation, or more properly acclimatization (which is basically an immediate physiological response to changing environment), the term “high-altitude adaptation” has strictly developed into the description of an irreversible, long-term physiological responses to high-altitude environments, associated with heritable behavioral and genetic changes. Perhaps, the phenomenon is most conspicuous, at least best documented, in human populations such as the Tibetans, the South Americans and the Ethiopians, who live in the otherwise uninhabitable high mountains of the Himalayas, Andes and Ethiopia respectively; and this represents one of the finest examples of natural selection in action.

Oxygen, essential for animal life, is proportionally abundant in the atmosphere with height from the sea level; hence, the highest mountain ranges of the world are considered unsuitable for habitation. Surprisingly, some 140 million people live permanently at high altitudes (>2,500 m) in North, Central and South America, East Africa, and Asia, and flourish very well for millennia in the exceptionally high mountains, without any apparent complications. This has become a recognized instance of the process of Darwinian evolution in humans acting on favorable characters such as enhanced respiratory mechanisms. As a matter of fact, this adaptation is so far the fastest case of evolution in humans that is scientifically documented. Among animals only few mammals (such as yak, ibex, Tibetan gazelle, vicunas, llamas, mountain goats, etc.) and certain birds are known to have completely adapted to high-altitude environments.

These adaptations are an example of convergent evolution, with adaptations occurring simultaneously on three continents. Tibetan humans and Tibetan domestic dogs found the genetic mutation in both species, EPAS1. This mutation has not been seen in Andean humans, showing the effect of a shared environment on evolution.

At elevation higher than 8,000 metres (26,000 ft), which is called the “death zone” in mountaineering, the available oxygen in the air is so low that it is considered insufficient to support life. And higher than 7,600 m is seriously lethal. Yet, there are Tibetans, Ethiopians and Americans who habitually live at places higher than 2,500 m from the sea level. For normal human population, even a brief stay at these places means mountain sickness, which is a syndrome of hypoxia or severe lack of oxygen, with complications such as fatigue, dizziness, breathlessness, headaches, insomnia, malaise, nausea, vomiting, body pain, loss of appetite, ear-ringing, blistering and purpling and of the hands and feet, and dilated veins. Amazingly for the native highlanders, there are no adverse effects; in fact, they are perfectly normal in all respects. Basically, the physiological and genetic adaptations in these people involve massive modification in the oxygen transport system of the blood, especially molecular changes in the structure and functions hemoglobin, a protein for carrying oxygen in the body. This is to compensate for perpetual low oxygen environment. This adaptation is associated with better developmental patterns such as high birth weight, increased lung volumes, increased breathing, and higher resting metabolism.

http://en.wikipedia.org/wiki/High-altitude_adaptation

Acute Mountain Sickness: Pathophysiology, Prevention, and Treatment

Chris Imraya, Alex Wright, Andrew Subudhie,, Robert Roache
Progress in Cardiovascular Diseases 52 (2010) 467–484
http://dx.doi.org:/10.1016/j.pcad.2010.02.003

Barometric pressure falls with increasing altitude and consequently there is a reduction in the partial pressure of oxygen resulting in a hypoxic challenge to any individual ascending to altitude. A spectrum of high altitude illnesses can occur when the hypoxic stress outstrips the subject’s ability to acclimatize. Acute altitude-related problems consist of the common syndrome of acute mountain sickness, which is relatively benign and usually self-limiting, and the rarer, more serious syndromes of high-altitude cerebral edema and high-altitude pulmonary edema. A common feature of acute altitude illness is rapid ascent by otherwise fit individuals to altitudes above 3000 m without sufficient time to acclimatize. The susceptibility of an individual to high altitude syndromes is variable but generally reproducible. Prevention of altitude-related illness by slow ascent is the best approach, but this is not always practical. The immediate management of serious illness requires oxygen (if available) and descent of more than 300 m as soon as possible. In this article, we describe the setting and clinical features of acute mountain sickness and high altitude cerebral edema, including an overview of the known pathophysiology, and explain contemporary practices for both prevention and treatment exploring the comprehensive evidence base for the various interventions.

Acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) strike people who travel too fast to high altitudes that lie beyond their current level of acclimatization. Understanding AMS and HACE is important because AMS can sharply limit recreation and work at high altitude. The syndromes can be identified early and reliably without sophisticated instruments, and when AMS and HACE are recognized early, most cases respond rapidly with complete recovery in a few hours (AMS) to days (HACE).

High-altitude headache (HAH) is the primary symptom of AMS. High-altitude headache in AMS usually occurs with some combination of other symptoms.
These are – insomnia, fatigue (beyond that expected from the day’s activities), dizziness, anorexia, and nausea. The headache often worsens during the night and with exertion. Insomnia is the next most frequent complaint. Poor sleep can occur secondary to periodic breathing, severe headache, dizziness, and shortness of breath, among other causes. Anorexia and nausea are common, with vomiting reported less frequently in trekkers to 4243 m.

AMS is distinguished only by symptoms. The progression of AMS to HACE is marked by altered mental status, including impaired mental capacity, drowsiness, stupor, and ataxia. Coma may develop as soon as 24 hours after the onset of ataxia or change in mental status. The severity of AMS can be scored using the Lake Louise Questionnaire, or the more detailed Environmental Symptoms Questionnaire, or by the use of a simple analogue scale. Today, more than 100 years after the first clear clinical descriptions of AMS and HACE, we have advanced our understanding of the physiology of acclimatization to high altitude, and the pathophysiology of AMS and HACE.

As altitude increases, barometric pressure falls (see Fig ). This fall in barometric pressure causes a corresponding drop in the partial pressure of oxygen (21% of barometric pressure) resulting in hypobaric hypoxia. Hypoxia is the major challenge humans face at high altitude, and the primary cause of AMS and HACE. It follows that oxygen partial pressure is more important than
geographic altitude, as exemplified near the poles where the atmosphere is thinner and, thus, barometric pressure is lower. Lower barometric pressure at the poles can result in oxygen partial pressures that are physiologically equivalent to altitudes 100 to 200 m higher at more moderate latitudes. We define altitude regions as high altitude (1500-3500 m), very high altitude (3500-5500 m), and extreme altitude (>5500 m).

Neurological consequences of increasing altitude

Neurological consequences of increasing altitude: The relation among altitude (classified as high [1500–3500 m], very high [3500-5500 m] and extreme [>5500 m]), the partial pressure of oxygen, and the neurological consequences of acute and gradual exposure to these pressure changes. Neurological consequences will vary greatly from person to person and with rate of ascent. HACE is far more common at higher altitudes, although there are case reports of HACE at 2500 m.

It is important for any discussion of AMS and HACE to have as a starting point an understanding of acclimatization. The process of acclimatization involves a series of adjustments by the body to meet the challenge of hypoxemia. While we have a general understanding of systemic changes associated with acclimatization, the underlying molecular and cellular processes are not yet fully described. Recent findings suggest that the process may be initiated by widespread molecular up-regulation of hypoxia inducible factor-1. Downstream processes ultimately act to offset hypoxemia, including elevated ventilation leading to a rise in arterial oxygen saturation (SaO2), a mild diuresis and contraction of plasma volume such that more oxygen is carried per unit of blood, elevated blood flow and oxygen delivery, and eventually a greater circulating hemoglobin mass. Acclimatization can be viewed as the end-stage process of how humans can best adjust to hypoxia. But optimal acclimatization takes from days to weeks, or perhaps even months.

The initial and immediate strategy to protect the body from hypoxia is to increase ventilation. This compensatory mechanism is triggered by stimulation of the carotid bodies, which sense hypoxemia (low arterial PO2), and increase central respiratory drive. This is a fast response, occurring within minutes of exposure to hypoxia persisting throughout high altitude exposure. This is why one cautions against the use of respiratory depressants such as alcohol and some sleeping medications, which can depress the hypoxic drive to breathe and may thus worsen hypoxemia. Pharmacological simulation of this natural process by acetazolamide, a respiratory stimulant and mild diuretic, largely protects from AMS and HACE by stimulating acclimatization. Circulatory responses are key to improving oxygen delivery, and are likely regulated by marked elevations in sympathetic activity. Field experience suggests that a marked elevation in early morning resting heart rate is a sign of challenges to acclimatization, perhaps secondary to increased hypoxemia, or dehydration. For the pathophysiology of AMS and HACE responses of the cerebral circulation are especially important. Maintenance of cerebral oxygen delivery is a critical factor for survival at high altitude. The balance between hypoxic vasodilation and hypocapnia-induced vasoconstriction determines overall cerebral blood flow (CBF). In a classic study, CBF increased 24% on abrupt ascent to 3810 m, and then returned to normal over 3 to 5 days. Recent studies, largely using regional transcranial Doppler measures of CBF velocity as a proxy for CBF, report discernible individual variation in the CBF response to hypoxia. All advanced brain imaging studies to date have shown both elevations in CBF in hypoxic humans and striking heterogeneity of CBF distribution in the hypoxic brain, with CBF rising up to 33% in the hypothalamus, and 20% in the thalamus with no other significant changes. Also, it is becoming clear that cerebral autoregulation, the process by which cerebral perfusion is maintained as blood pressure varies, is impaired in hypoxia. Thus, hypoxia modulates cerebral autoregulation and raises interesting questions about the importance of this process in AMS and acclimatization, since it appears to be a uniform response in all humans made hypoxemic. Further, hematocrit and hemoglobin concentration are elevated after 12 to 24 hours of hypoxic exposure due to a fall in plasma volume, but after several weeks, plasma volume returns to near sea level values. Normalization of plasma volume coupled with an increase in red cell mass secondary to the hypoxia stimulated erythropoiesis leads to an increase in total blood volume after several weeks of acclimatization. Adequate iron stores are required for adequate hematologic acclimatization to high altitude. Acclimatization, then, is a series of physiological responses to hypoxia that serve to offset hypoxemia, improve systemic oxygen delivery, and avoid AMS and HACE. When acclimatization fails, or the challenge of hypoxia is too great, AMS and HACE can develop.

AMS occurs in susceptible individuals when ascent to high altitude outpaces the ability to acclimatize. For example, most people ascending very rapidly to high altitude will get AMS. The symptoms, although often initially incapacitating, usually resolve in 24 to 48 hrs. The incidence and severity of AMS depend on the rate of ascent and the altitude attained, the length of time at altitude, the degree of physical exertion, and the individual’s physiological susceptibility. The chief significance of AMS is that planned activities may be impossible to complete during the first few days at a new altitude due to symptoms. In addition, in a few individuals, AMS may progress to life-threatening HACE or HAPE. At 4000 m and above, the incidence of AMS ranges from 50% to 65% depending on the rate and mode of ascent, altitude reached, and sleeping altitude. A survey of 3158 travelers visiting resorts in the Rocky Mountains of Colorado revealed that 25% developed AMS, and most decreased their daily activity because of their symptoms.

Singh et al. proposed that the high-altitude syndromes are secondary to the body’s responses to hypobaric hypoxia, not due simply to hypoxemia. They based this conclusion on 2 observations:

there is a delay between the onset of hypoxia and the onset of symptoms after ascent (from hours to days), and
not all symptoms are immediately reversed with oxygen.

On the other hand, scientists have long assumed that AMS and HACE are due solely to hypoxia, based largely on 2 reports:

the pioneering experiments of Paul Bert and
the Glass House experiment of Barcroft.

When these assumptions were tested in a laboratory setting to study symptom responses to hypobaric hypoxia (simulated high altitude), hypoxia alone, and hypobaric normoxia, AMS occurred soonest and with greater severity with simulated altitude, compared with either normobaric hypoxia or normoxic hypobaria. In 2 studies, one in normobaric hypoxia found no MRI signs of vasogenic edema but suggested that AMS was associated with “cytotoxic edema”, whereas a comparable study in hypobaric hypoxia found combined vasogenic and intracellular edema. The conclusions from the 2 studies have very different implications for refining a theory of the pathophysiology of AMS. Although the studies were not designed for a direct comparison between hypobaria and hypoxia, the discrepancy points out an assumption about normobaric hypoxia and the pathophysiology of AMS that may warrant further investigation.

Our central hypothesis regarding the pathophysiology of AMS, and by extension of HACE, is that it is centered on dysfunction within the brain. This is not a new idea, but it is one of current intense interest thanks to advances in brain imaging and neuroscience techniques. Barcroft, writing in 1924, argued that the brain’s response to hypoxia was central to understanding the pathophysiology of mountain sickness.

A low ventilatory response to hypoxia coupled with increased symptoms of AMS led to intensive investigation of a link between the chemical control of ventilation and the pathogenesis of AMS. The results of these investigations suggest that for most people, the ventilatory response to hypoxia has little predictive value for AMS risk. Only if the extremes of ventilator responsiveness are contrasted can accurate predictions be made, where those with extremely low ventilatory drives being more likely to suffer AMS. At the extreme end of the distribution (i.e., for very high responses), the protective role of a brisk hypoxic ventilatory response may be due to increased arterial oxygen content and cerebral oxygen delivery despite mild hypocapnic cerebral vasoconstriction.

Hansen and Evans were the first to publish a comprehensive hypothesis of the pathophysiology of AMS centered on the brain. Their theory posited that compression of the brain, either by increased cerebral venous volume, reduced absorption of cerebral spinal fluid, or increased brain-tissue hydration (edema), initiates the development of the symptoms and signs of AMS and HACE. Ross built on these ideas with his “tight fit hypothesis,” published in 1985, and others have developed these ideas into a series of testable hypotheses congruent with today’s knowledge of AMS and HACE. The tight fit hypothesis states that expanded intracranial volume (due to the reasons put forth by Hansen and Evans, or other causes) plus the volume available for intracranial buffering of that expanded volume would predict who would get AMS. Greater buffering capacity leads to AMS resistance, lower buffering capacity, or a ‘tight fit’ of the brain in the cranial vault, would lead to greater AMS susceptibility. Overall, it is clear that brain volume increases in humans on exposure to hypoxia. It is less certain whether this elevation in brain volume plays a role in AMS.

Hackett’s pioneering MRI study in HACE, with marked white matter edema suggestive of a vasogenic origin, has led to a decade of studies looking for a similar finding in AMS. In moderate to severe AMS, all imaging studies have shown some degree of cerebral edema. But in mild to moderate AMS, admittedly an arbitrary and subjective distinction, brain edema is present in some MRI studies of AMS subjects, but not in all. It seems reasonable to conclude from the available data that the increase in brain volume observed is at least partially due to brain edema, and that earlier studies missed the edema more for technical than physiological reasons. It is less clear whether the brain edema is largely of intracellular or vasogenic origin, and what role if any it plays in the pathophysiology of AMS.

Although we support transcranial doppler for many investigations in integrative physiology, the complex interplay of hypoxia and hypocapnia that is present in acutely hypoxic humans may present a situation where whole brain imaging is a more reliable and accurate tool to discern the role of CBF in the onset of AMS. To date, no brain imaging studies have addressed global cerebral perfusion in AMS.

The management of AMS and HACE is based on our current understanding of the physiological and pathophysiological responses to hypoxia. Hypoxia itself, however, does not immediately lead to AMS as there is a delay of several hours after arrival at high altitude before symptoms develop. Increased knowledge of hypoxic inducible factor and cytokines that alter capillary permeability may lead to the discovery of new drugs for the prevention and alleviation of AMS and HACE.

Much work has focused on the role of vascular endothelial growth factor (VEGF), a potent permeability factor up-regulated by hypoxia. Some studies have found no evidence of an association of changes in plasma concentrations of VEGF and AMS, whereas others support the hypothesis that VEGF contributes to the pathogensis of AMS. Clearly a better understanding of the mechanisms of increased capillary permeability of cerebral capillaries will greatly enhance the management of AMS and HACE.

Flying high: A theoretical analysis of the factors limiting exercise performance in birds at altitude

Graham R. Scott, William K. Milsom
Respiratory Physiology & Neurobiology 154 (2006) 284–301
http://dx.doi.org:/10.1016/j.resp.2006.02.012

The ability of some bird species to fly at extreme altitude has fascinated comparative respiratory physiologists for decades, yet there is still no consensus about what adaptations enable high altitude flight. Using a theoretical model of O2 transport, we performed a sensitivity analysis of the factors that might limit exercise performance in birds. We found that the influence of individual physiological traits on oxygen consumption (˙VO2 ) during exercise differed between sea level, moderate altitude, and extreme altitude. At extreme altitude, hemoglobin (Hb) O2 affinity, total ventilation, and tissue diffusion capacity for O2 (DTO2) had the greatest influences on VO2; increasing these variables should therefore have the greatest adaptive benefit for high altitude flight. There was a beneficial interaction between DTO2 and the P50 of Hb, such that increasing DTO2 had a greater influence on VO2 when P50 was low. Increases in the temperature effect on P50 could also be beneficial for high flying birds, provided that cold inspired air at extreme altitude causes a substantial difference in temperature between blood in the lungs and in the tissues. Changes in lung diffusion capacity for O2, cardiac output, blood Hb concentration, the Bohr coefficient, or the Hill coefficient likely have less adaptive significance at high altitude. Our sensitivity analysis provides theoretical suggestions of the adaptations most likely to promote high altitude flight in birds and provides direction for future in vivo studies.

The bird lung is unique among the lungs of air-breathing vertebrates, with a blood flow that is crosscurrent to gas flow, and a gas flow that occurs unidirectionally through rigid parabronchioles. As such, bird lungs are inherently more efficient than the lungs of other air-breathing vertebrates (Piiper and Scheid, 1972, 1975). While this may partially account for the greater hypoxia tolerance of birds in general when compared to mammals (cf. Scheid, 1990), its presence in all birds excludes the crosscurrent lung as a possible adaptation specific to high altitude fliers. Similarly, an extremely small diffusion distance across the blood–gas interface compared to other air breathers seems to be a characteristic of all bird lungs, and not just those of high fliers (Maina and King, 1982; Powell and Mazzone, 1983; Shams and Scheid, 1989). Partly because of this small diffusion distance, the inherent O2 diffusion capacity across the gas–blood interface (DLO2) is generally high in birds. Interestingly, pulmonary vasoconstriction does not appear to increase during hypoxia in bar-headed geese (Faraci et al., 1984a). This may be a significant advantage during combined exercise and severe hypoxia, and suggests that regulation of lung blood flow could be important in high altitude birds. In addition, the CO2/pH sensitivity of ventilation is commonly assessed by comparing the isocapnic and poikilocapnic hypoxic ventilatory responses; however, the isocapnic ventilatory responses to hypoxia of both low and high altitude birds have not been compared. In this regard, the ventilator response in high altitude birds may also depend on their capacity to maintain intracellular pH during alkalosis, or to buffer changes in extracellular pH due to hyperventilation. It therefore remains to be conclusively determined whether high altitude fliers have a greater capacity to increase ventilation during severe hypoxia.

After diffusing into the blood in the lungs, oxygen is primarily circulated throughout the body bound to hemoglobin. A high cardiac output is therefore important for exercise at high altitude to supply the working muscle with adequate amounts of O2. Indeed, animals selectively bred for exercise performance have higher maximum cardiac outputs, as do species that have evolved for exercise performance. Whether cardiac output limits exercise performance per se, however, is less clear; other factors may limit intense exercise, and in more athletic species (or individuals) cardiac output may be higher simply out of necessity. Excessive cardiac output may even be detrimental if blood transit times in the lungs or tissues are substantially reduced. Unfortunately, very little is known about cardiac performance in high flying birds. Both the high altitude bar-headed goose and the low altitude pekin duck can increase cardiac output at least five-fold during hypoxia at rest (Black and Tenney, 1980), but no comparison of maximum cardiac performance has been made between high and low altitude birds.

Once oxygenated blood is circulated to the tissues, O2 moves to the tissue mitochondria, the site of oxidative phosphorylation and oxygen consumption. Transport of oxygen from the blood to the mitochondria involves several steps. Oxygen must first dissociate from Hb and diffuse through the various compartments of the blood, but in both birds and mammals the conductances of these steps are high, and are unlikely to impose much of a limitation to O2 transport. In contrast, diffusion across the vascular wall and through the extracellular spaces is thought to provide the most sizeable limitation to O2 transport. Consequently, the size of the capillary–muscle fiber interface is an extremely important determinant of a muscle’s aerobic capacity. Finally, oxygen diffuses across the muscle fiber membrane and moves through the cytoplasm until it associates with cytochrome c oxidase, the O2 acceptor in the mitochondrial electron transport chain. Myoglobin probably assists intracellular O2 transport, so diffusion through the muscle likely provides very little resistance to O2 flux.

It is obvious that the ability of some bird species to fly at extreme altitudes is poorly understood. The adaptive benefit of high hemoglobin oxygen affinity is well established, but its relative importance is unknown. Some evidence suggests that traits increasing oxygen diffusion capacity in flight muscle are adaptive in high fliers as well, but the adaptive significance of differences in the respiratory and cardiovascular systems of high altitude fliers is not clear. The remainder of this study assesses these possibilities using theoretical sensitivity analysis, and explores potential adaptations for high altitude flight in birds.

Oxygen transport in birds

Oxygen transport in birds. The crosscurrent parabronchial lung is unidirectionally ventilated by air sacs, and oxygen diffuses into blood capillaries from air capillaries (not shown) all along the length of the parabronchi. Oxygen is then circulated in the blood, and diffuses to mitochondria in the tissues. The rate of oxygen transport at both the lungs and tissues can be calculated using the Fick equation, and the amount of O2 transferred from the lungs into the blood can be calculated using an oxygen conservation equation.

Oxygen tensions in the lung

Oxygen tensions in the lung (A) and tissue (B) capillaries during normoxia. In the crosscurrent avian lung, PO2 varies in two dimensions: PO2 increases along the path of blood flow through the lungs, but does not increase by as much at the end of the parabronchi as at the start (gas PO2 decreases along the length of the parabronchi). In the tissues, blood PO2 decreases continuously along the capillary length as O2 diffuses to tissue mitochondria. To reach a solution, our model iterates between gas transport calculations in the lungs (A) and tissues (B) until a stable result is reached.

varying different biochemical features of hemoglobin (Hb) on oxygen consumption

The effects of varying different biochemical features of hemoglobin (Hb) on oxygen consumption during exercise in normoxia (PIO2 of 150 Torr; red), moderate hypoxia (84 Torr; green dashed), and severe hypoxia (30 Torr; dark blue). (A) P50, the PO2 at 50% Hb saturation; (B and C) Bohr coefficient (φ); and (D and E) Hill coefficient (n) (see Section 2 for a mathematical description of each). In (B)–(E), the effects of each variable were assessed at the P50 of pekin ducks (40 Torr; B and D) as well as the P50 of bar-headed geese (25 Torr; C and E).

Unlike in vivo studies, theoretical sensitivity analyses allow individual physiological variables to be altered independently so their individual effects on oxygen consumption can be assessed. By applying this analysis to hypoxia in birds, we feel we can predict which factors most likely limit oxygen consumption and exercise performance. As a consequence, our analysis identifies which steps in the oxygen cascade can provide the basis for adaptive change in birds that evolved for high altitude flight, namely ventilation and tissue diffusion capacity.

Since our interest was in the factors limiting exercise performance at altitude, the starting data for our model were obtained from previous studies on pekin ducks near maximal oxygen consumption. These ducks were exercising on a treadmill, however, and were not flying. Unfortunately, to the best of our knowledge only one previous study has made all the required measurements for this analysis during flight, and this was only done in normoxia (in pigeons, Butler et al., 1977). Pekin ducks are the only species for which we could find all the required measurements for our analysis during exercise in both normoxia and hypoxia. Only the lung and tissue diffusion capacities remained to be calculated in our analysis, but previous experimental determinations of DLO2 in pekin ducks were similar to the values calculated in this study (Scheid et al., 1977). Similar values for DTO2 are not available.

The physiological variables limiting exercise performance in birds during moderate hypoxia are similar to those limiting performance in normoxia. DTO2 continues to pose the greatest limitation, and limitations imposed by the circulation (˙Q and CHb) are still greater at a lower P50. Unlike normoxia, however, ˙VO2 in moderate hypoxia appears to be limited less by the circulation and more by respiratory variables, as is also the case in humans (Wagner, 1996). The most substantial difference between severe hypoxia and normoxia/moderate hypoxia is in the effects of altering ventilation. Ventilation appears to become a major limitation to exercise performance at extreme altitude. DTO2 also appears to limit ˙VO2 in severe hypoxia, but only at lower P50 values. This is not entirely unsurprising: in severe hypoxia the venous blood of pekin ducks (a species which has a higher P50) is almost completely deoxygenated in vivo, so there are no possible benefits of increasing DTO2 . At the lower P50, there is a substantially higher arterial oxygen content, so more oxygen can be removed, and increasing DTO2 can have a greater influence. In humans during severe hypoxia, DTO2, DLO2, and ˙V have the greatest influence on exercise performance.

Tissue diffusion capacity should also be adaptive in high altitude birds with a high hemoglobin O2 affinity. In the present study, a simultaneous decrease in P50 (from 40 to 25 Torr) and increase in DTO2 (twofold) increased ˙VO2 by 51%. Thus, in high flying birds that are known to have a low P50, such as the barheaded goose and Ruppell’s griffon (Gyps rueppellii), increases in flight muscle diffusion capacity should be of extreme importance. This suggestion is supported by research demonstrating greater muscle capillarization in bar-headed geese than in low altitude fliers, as the size of the capillary–muscle fiber interface is known to be the primary structural determinant of O2 flux into the muscle.

Our analysis suggests that an enhanced capacity to increase ventilation should also benefit birds significantly in severe hypoxia, and could therefore be an important source of adaptation for high altitude flight. This is likely true regardless of P50; although there is a small amount of interaction between P50 and ventilation, increasing ˙V always had a substantial effect on oxygen consumption. Data from the literature addressing this possibility have unfortunately been inconclusive. Both bar-headed geese and pekin ducks can effectively increase ventilation, thus reducing the inspired-arterial O2 difference, during severe poikilocapnic hypoxia at rest, as well as during moderate poikilocapnic hypoxia and running exercise.

oxyhemoglobin dissociation curve

In contrast to the Bohr effect and Hill coefficient, the temperature effect on Hb-O2 binding affinity may have a substantial effect on oxygen consumption, and may therefore be a source of adaptive change for high altitude flight. An effect of temperature on ˙VO2 may arise if hyperventilation during flight at extreme altitude cools the pulmonary blood. This would reduce the P50 of Hb in the lungs, and thus facilitate oxygen uptake. When this blood enters the exercising muscles it would then be rewarmed to body temperature, and oxygen would be released from Hb. Our modelling suggests that a temperature effect on Hb could significantly enhance ˙VO2 . The greater the difference in temperature between blood in the lungs and in the muscles, and the greater the temperature effect on Hb-O2 binding, the greater the increase in ˙VO2 . At normal levels of temperature sensitivity, the increase in ˙VO2 was approximately 5% for every 1 ◦C difference. It could be adaptive at high altitude to alter the magnitude of the temperature effect on Hb while allowing lung temperature to fall. At present, however, it is unknown whether the Hb of high altitude birds has a heightened sensitivity to temperature, or whether pulmonary blood is actually cooled during high altitude flight.

Using a theoretical sensitivity analysis that allows individual physiological variables to be altered independently, we have identified the factors most likely to limit oxygen consumption and exercise performance in birds, and by extension, the physiological changes that are likely adaptive for high altitude flight. The adaptive benefits of some of these changes, in particular hemoglobin oxygen affinity, are already well established for high flying birds. For other traits, such as an enhanced hypoxic ventilatory response or O2 diffusion capacity of flight muscle, adaptive differences have not been conclusively recognized in studies in vivo. Furthermore, the beneficial interaction between increasing DTO2 and decreasing hemoglobin P50 has not yet been demonstrated in vivo. Our theoretical analysis suggests that changes in these respiratory processes could also adapt birds to environmental extremes, and future studies should explore these findings.

Adaptation and Convergent Evolution within the Jamesonia-Eriosorus Complex in High-Elevation Biodiverse Andean Hotspots

Patricia Sanchez-Baracaldo, Gavin H. Thomas
PLoS ONE 9(10): e110618. http://dx.doi.org:/10.1371/journal.pone.0110618

The recent uplift of the tropical Andes (since the late Pliocene or early Pleistocene) provided extensive ecological opportunity for evolutionary radiations. We test for phylogenetic and morphological evidence of adaptive radiation and convergent evolution to novel habitats (exposed, high-altitude paramo habitats) in the Andean fern genera Jamesonia and Eriosorus. We construct time-calibrated phylogenies for the Jamesonia-Eriosorus clade. We then use recent phylogenetic comparative methods to test for evolutionary transitions among habitats, associations between habitat and leaf morphology, and ecologically driven variation in the rate of morphological evolution. Paramo species (Jamesonia) display morphological adaptations consistent with convergent evolution in response to the demands of a highly exposed environment but these adaptations are associated with microhabitat use rather than the paramo per se. Species that are associated with exposed microhabitats (including Jamesonia and Eriorsorus) are characterized by many but short pinnae per frond whereas species occupying sheltered microhabitats (primarily Eriosorus) have few but long pinnae per frond. Pinnae length declines more rapidly with altitude in sheltered species. Rates of speciation are significantly higher among paramo than non-paramo lineages supporting the hypothesis of adaptation and divergence in the unique Pa´ramo biodiversity hotspot.

AltitudeOmics: Rapid Hemoglobin Mass Alterations with Early Acclimatization to and De-Acclimatization from 5,260 m in Healthy Humans

Benjamin J. Ryan, NB Wachsmuth, WF Schmidt, WC Byrnes, et al.
PLoS ONE 9(10): e108788. http://dx.doi.org:/10.1371/journal.pone.0108788

It is classically thought that increases in hemoglobin mass (Hb mass) take several weeks to develop upon ascent to high altitude and are lost gradually following descent. However, the early time course of these erythropoietic adaptations has not been thoroughly investigated and data are lacking at elevations greater than 5,000 m, where the hypoxic stimulus is dramatically increased. As part of the AltitudeOmics project, we examined Hb mass in healthy men and women at sea level (SL) and 5,260 m following 1, 7, and 16 days of high altitude exposure (ALT1/ALT7/ALT16). Subjects were also studied upon return to 5,260 m following descent to 1,525 m for either 7 or 21 days. Compared to SL, absolute Hb mass was not different at ALT1 but increased by 3.7-5.8% (mean 6 SD; n = 20; p<0.01) at ALT7 and 7.6-6.6% (n = 21; p=0.001) at ALT16. Following descent to 1,525 m, Hb mass was reduced compared to ALT16 (-6.0+3.7%; n = 20; p = 0.001) and not different compared to SL, with no difference in the loss in Hb mass between groups that descended for 7 (-6.3+3.0%; n = 13) versus 21 days (-5.7+5.0; n = 7). The loss in Hb mass following 7 days at 1,525 m was correlated with an increase in serum ferritin
(r =20.64; n = 13; p,0.05), suggesting increased red blood cell destruction. Our novel findings demonstrate that Hb mass increases within 7 days of ascent to 5,260 m but that the altitude-induced Hb mass adaptation is lost within 7 days of descent to 1,525 m. The rapid time course of these adaptations contrasts with the classical dogma, suggesting the need to further examine mechanisms responsible for Hb mass adaptations in response to severe hypoxia.

Cardiovascular adjustments for life at high altitude

Roger Hainsworth, Mark J. Drinkhill
Respiratory Physiology & Neurobiology 158 (2007) 204–211
http://dx.doi.org:/10.1016/j.resp.2007.05.006

The effects of hypobaric hypoxia in visitors depend not only on the actual elevation but also on the rate of ascent. There are increases in sympathetic activity resulting in increases in systemic vascular resistance, blood pressure and heart rate. Pulmonary vasoconstriction leads to pulmonary hypertension, particularly during exercise. The sympathetic excitation results from hypoxia, partly through chemoreceptor reflexes and partly through altered baroreceptor function. Systemic vasoconstriction may also occur as a reflex response to the high pulmonary arterial pressures. Many communities live permanently at high altitude and most dwellers show excellent adaptation although there are differences between populations in the extent of the ventilatory drive and the erythropoiesis. Despite living all their lives at altitude, some dwellers, particularly Andeans, may develop a maladaptation syndrome known as chronic mountain sickness. The most prominent characteristic of this is excessive polycythemia, the cause of which has been attributed to peripheral chemoreceptor dysfunction. The hyperviscous blood leads to pulmonary hypertension, symptoms of cerebral hypoperfusion, and eventually right heart failure and death.

High altitude places are not only destinations of adventurous travelers, many people are born, live their lives and die in these cold and hypoxic regions. According to WHO, in 1996 there were approximately 140 million people living at altitudes over 2,500m and there are several areas of permanent habitation at over 4,000 m. These are in three main regions of the world: the Andes of South America, the highlands of Eastern Africa, and the Himalayas of South-Central Asia. This review is concerned with the effects of exposure to high altitude on the cardiovascular system and its autonomic control, in visitors, and the means by which the permanent high altitude dwellers have adapted to their environment.

For visitors the period of initial adaptation, i.e. the first days and weeks following arrival at attitude, is a critical time since it is during this period that acute mountain sickness and/or pulmonary edema may occur. The processes of adaptation occurring during this initial period may well determine the individual’s ability to continue to function normally. Recent studies in animals and man have highlighted the role of the autonomic nervous system in adaptation and in particular the importance of sympathetic activation of the cardiovascular system following high altitude exposure.

An increase in resting heart rate in response to acute hypoxia has been
described in several species including man. Vogel and Harris (1967)
investigated the effects of simulated exposure to high altitude in man
at pressures equivalent to 600, 3,400 and 4,600m using a hypobaric
chamber. Each level of chamber pressure was developed over a 30 min
period andwas maintained for 48 h in an attempt to simulate expedition
conditions. After 10 h at the equivalent of 3,400 m resting
heart rate was significantly increased and by 40 h it had increased by
16% from the resting value at 600 m. At 4,600 m it increased by 34%.
Similar findings, an increase in heart rate of 18%, were shown following
ascent to 4,300 m for periods up to 5 weeks. However, this study also
demonstrated that the rate of ascent also influenced the magnitude of
the heart rate increase. A gradual increase in altitude over a period
of 2 weeks resulted in the resting heart rate increasing by 25%
compared with an abrupt ascent which resulted in an increase of
only 9%. As subjects acclimatize at altitudes up to about 4,500 m
much of the increase in heart rate is lost and resting heart rates
return towards their sea level values. Acute hypoxia also causes
increases in cardiac output both at rest and for given levels of
exercise compared with values during normoxia.

The effect of hypoxia on the pulmonary circulation is dramatic
resulting in pulmonary hypertension caused by an increase in
pulmonary vascular resistance. The onset has been shown in man
to be very rapid, reaching a maximum within 5 min. Zhao et al.
(2001) demonstrated that breathing 11% oxygen for 30 min
increased mean pulmonary artery pressure by 56%, from 16 to
25 mmHg. The effect of hypoxia on the pulmonary circulation is
even more pronounced during exercise, as demonstrated in studies
carried out on subjects of Operation Everest II. Resting pulmonary
artery pressure increased from 15 mmHg at sea level to 34 mmHg
at the equivalent of 8,840 m. During near maximal exercise at
8,840 m it increased from the sea level value of 33–54 mm Hg.
In the short term the mechanism of this pulmonary artery vaso-
constriction has been shown to involve inhibition of O2 sensitive
K+ channels leading to depolarization of pulmonary artery smooth
muscle cells and activation of voltage gated Ca2+ channels. This
causes Ca2+ influx and vasocon-striction. This process is
immediately reversed by breathing oxygen.

Healthy high altitude residents show excellent adaptation to their
environment. These adaptations are likely to be associated with
altered gene expression as the expression of genes associated with
vascular control and reactions to hypoxia have been found to be high
in altitude dwellers. Different communities, however, seem to adopt
different adaptation strategies. For example Andeans hyperventilate
to decrease end-tidal and arterial CO2 levels to as low as 25 mmHg
and have hemoglobin levels well above those in sea-level people.
Tibetans Hyperventilate but have normal hemoglobin levels below
4,000 m. Ethiopian highlanders, on the other hand, have CO2 and
hemoglobin levels similar to those of sea-level dwellers.

Blood volumes are larger in high altitude dwellers. In Andeans this
is due to large packed cell volumes whereas in Ethiopians it was the
plasma volumes that were large. Probably as the result of the large
blood volumes, tolerance to orthostatic stress was greater than that
in sea-level residents.

CMS is a condition frequently found in long term residents of high
altitudes, particularly in the Andes where it is a major public health
problem. It also occurs in residents on the Tibetan plateau, although
not in Ethiopians. Patients with CMS develop excessive polycythemia
and various clinical features including dyspnea, palpitations, insomnia,
dizziness, headaches, confusion, loss of appetite, lack of mental
concentration and memory alterations. Patients may also complain
of decreased exercise tolerance, bone pains, acral paresthesia and
occasionally hemoptysis. The impairment of mental function may
be reversed by phlebotomy. Physical examination reveals cyanosis,
due to the combination of polycythemia and low oxygen saturation,
and a marked pigmentation of the skin exposed to the sun.
Hyperemia of conjunctivae is characteristic and the retinal vessels
are also dilated and engorged. The second heart sound is frequently
accentuated and there is an increased cardiac size, mainly due to
right ventricular hypertrophy. As the condition progresses, overt
congestive heart failure becomes evident, characterized by dyspnea
at rest and during mild effort, peripheral edema, distension of
superficial veins, and progressive cardiac dilation.

The major mechanism for the control of blood pressure is through
regulation of peripheral vascular resistance, but most studies have
examined only the control of heart rate. We have recently studied
the responses of forearm vascular resistance to carotid baroreceptor
stimulation in high altitude residents with and without CMS, both at
their resident altitude and shortly after descent to sea level. Results
showed that baroreflex “set point” was higher in CMS, but only at
altitude. At sea level, values were similar.

The chronic hypoxia at high altitude stresses many of the body’s
homeostatic mechanisms. There have been many investigations
which have examined the effects on respiration. However, cardio-
vascular effects are no less important and it is largely through effects
on the cardiovascular system that both acute and chronic mountain
sickness are caused. The hypoxia exerts both direct and reflex effects.
In the lung it causes vasoconstriction and pulmonary hypertension.
The sympathetic nervous system is excited partly through a central
effect of the hypoxia, through stimulation of chemoreceptors and
possibly pulmonary arterial baroreceptors and altered systemic
baroreceptor function. In some individuals the excessive hemopoiesis
causes increased blood viscosity and tissue hypoperfusion leading
to the syndrome of chronic mountain sickness.

New Insights in the Pathogenesis of High-Altitude Pulmonary Edema

Urs Scherrer, Emrush Rexhaj, Pierre-Yves Jayet, et al.
Progress in Cardiovascular Diseases 52 (2010) 485–492
http://dx.doi.org:/10.1016/j.pcad.2010.02.004

High-altitude pulmonary edema is a life-threatening condition occurring in predisposed but otherwise healthy individuals. It therefore permits the study of underlying mechanisms of pulmonary edema in the absence of confounding factors such as coexisting cardiovascular or pulmonary disease, and/or drug therapy. There is evidence that some degree of asymptomatic alveolar fluid accumulation may represent a normal phenomenon in healthy humans shortly after arrival at high altitude. Two fundamental mechanisms then determine whether this fluid accumulation is cleared or whether it progresses to HAPE: the quantity of liquid escaping from the pulmonary vasculature and the rate of its clearance by the alveolar respiratory epithelium. The former is directly related to the degree of hypoxia induced pulmonary hypertension, whereas the latter is determined by the alveolar epithelial sodium transport. Here, we will review evidence that, in HAPE-prone subjects, impaired pulmonary endothelial and epithelial NO synthesis and/or bioavailability may represent a central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and, in turn, capillary stress failure and alveolar fluid flooding. We will then demonstrate that exaggerated pulmonary hypertension, although possibly a condition sine qua non, may not always be sufficient to induce HAPE and how defective alveolar fluid clearance may represent a second important pathogenic mechanism.

Cerebral Blood Flow at High Altitude

Philip N. Ainslie and Andrew W. Subudhi
High Altitude Medicine & Biology 2014; 15(2): 133–140
http://dx.doi.org:/10.1089/ham.2013.1138

This brief review traces the last 50 years of research related to cerebral blood flow (CBF) in humans exposed to high altitude. The increase in CBF within the first 12 hours at high altitude and its return to near sea level values after 3–5 days of acclimatization was first documented with use of the Kety-Schmidt technique in 1964. The degree of change in CBF at high altitude is influenced by many variables, including arterial oxygen and carbon dioxide tensions, oxygen content, cerebral spinal fluid pH, and hematocrit, but can be collectively summarized in terms of the relative strengths of four key integrated reflexes:

hypoxic cerebral vasodilatation;
2) hypocapnic cerebral vasoconstriction;
3) hypoxic ventilatory response; and
4) hypercapnic ventilatory response.

Understanding the mechanisms underlying these reflexes and their interactions with one another is critical to advance our understanding of global and regional CBF regulation. Whether high altitude populations exhibit cerebrovascular adaptations to chronic levels of hypoxia or if changes in CBF are related to the development of acute mountain sickness are currently unknown; yet overall, the integrated CBF response to high altitude appears to be sufficient to meet the brain’s large and consistent demand for oxygen.

Relative to its size, the brain is the most oxygen dependent organ in the body, but many pathophysiological and environmental processes may either cause or result in an interruption to its oxygen supply. As such, studying the brain at high altitude is an appropriate model to investigate both acute and chronic effects of hypoxemia on cerebrovascular function. The cerebrovascular responses to high altitude are complex, involving mechanistic interactions of physiological, metabolic, and biochemical processes.

This short review is organized as follows: An historical overview of the earliest CBF measurements collected at high altitude introduces a summary of reported CBF changes at altitude over the last 50 years in both lowlanders and high-altitude natives. The most tenable candidate mechanism(s) regulating CBF at altitude are summarized with a focus on available data in humans, and a role for these mechanisms in the pathophysiology of AMS is considered. Finally, suggestions for future directions are provided.

Angelo Mosso (1846–1910) is undoubtedly the forefather of high altitude cerebrovascular physiology. In order to pursue his principal curiosity of the physiological effects of hypobaria, Mosso built barometric chambers and was reported to expose himself pressures as low as 192 mmHg (equivalent to > 10,000 m). He was also responsible for the building of the Capanna Margherita laboratory on Monta Rosa at 4,559 m. In both settings, Mosso utilized his hydrosphygmomanometer to measure changes in ‘‘brain pulsations’’ in patients that had suffered removal of skull sections, due to illness or trauma. Indicative of changes in CBF, these recordings preceded the next estimates of CBF in humans by some 50 years.

At sea level, Kety and Schmidt (1945) were the first to quantify human CBF using an inert tracer (nitrous oxide, N2O) combined with arterial and jugular venous sampling. This method for the measurement of global CBF is based on the Fick principle, whereby the integrated difference of multiple arterial and venous blood samples during the first 10 or more minutes after the sudden introduction into the lung of a soluble gas tracer is inversely proportional to cerebral blood flow. In 1948, they showed that breathing 10% oxygen increased CBF by 35%; however, it was not until 1964 that the first measurements of CBF were made in humans at high altitude. The motivation for these high altitude experiments was stimulated, in part, from the earlier discovery of the brain’s ventral medullary cerebrospinal fluid (CSF) pH sensors in animals. Following the location of these central chemoreceptors, Severinghaus and colleagues examined in humans the role of CSF pH and bicarbonate in acclimatization to high altitude (3,810 m) at the White Mountain (California, USA) laboratories (Severinghaus et al., 1963). A year later, at the same location, John Severinghaus performed his seminal study of CBF at high altitude. He was joined by Tom Hornbein—shortly after his first ascent of Everest by the West Ridge—who was part of the research team and also volunteered for the study (Fig.). The results showed clear time dependent changes in CBF during acclimatization to high altitude (HA).

the Kety-Schmidt nitrous oxide method of measuring CBF

From left to right, Larry Saidman (administering the gas), Tom Hornbien (volunteer), Ed Munson (drawing jugular venous blood samples), and John Severinghaus. Here (1964) the Kety-Schmidt nitrous oxide method of measuring CBF is used. The subject breathed about 15% N2O for 15 min while arterial and jugular venous blood was frequently sampled. (B) Results from Severinghaus et al. (1966). Graphs shows that CBF as estimated by cerebral A-VO2 differences from sea level controls increased about 24% within hours of arrival at 3810 m, and fell over 4 days to about 13% above control. CBF by the N2O method was increased by 40% on day 1, and returned to 6% above control on day 4. However, the N2O method data had greater variance. Acute normoxia on day 1 and day 4 returned CBF to sea level values within 15 min. Photograph courtesy of Dr. John W Severinghaus.

Native Tibetan (or Himalayan) and Andean populations arrived approximately 25,000 and 11,000 years ago, suggesting that these populations either carried traits that allowed them to thrive at high altitude or were able to adapt to the environment. The physiological and genetic traits associated with native high-altitude populations have been elegantly reviewed (Beall, 2007; Erzurum et al., 2007; Frisancho, 2013). As such, this topic is briefly summarized here with the focus on CBF at altitude in context of Andean and Tibetan high-altitude residents.

In general, native Andeans have lower CBF values compared to sea level natives. The first evidence suggesting lower flow was reported in 8 Peruvian natives living at 4300m altitude in Cerro de Pasco (Milledge and Sørensen, 1972). The authors found the mean arterial–venous oxygen content difference across the brain was 7.9 – 1 vol%, about 20% higher than the published sea level mean of 6.5 vol%. They suggested that CBF probably was proportionately about 20% below sea level normal values, assuming that brain metabolic rate was normal, and postulated that the mechanism might be high blood viscosity given the high hematocrit (58 – 6%) in these subjects. However, since the cerebral metabolic rate for oxygen (CMRO2) is constant even in severe hypoxia (Kety and Schmidt 1948b; Ainslie et al. 2013), the inverse linear relationship between CBF and arterial–venous oxygen content differences could also explain the reduction in CBF, as less flow would be needed to match the oxygen demand of the brain when arterial content is elevated. A similar study (Sørensen et al., 1974), using arterio-venous differences combined (in a subgroup) with a modified version of Kety–Schmidt method (krypton instead of N2O,) conducted in high-altitude residents in La Paz in Bolivia at 3800 m, also reported a 15%–20% reduction in CBF (with a reported average hematocrit of 50%) compared to a sea level control group.

Percent changes in cerebral blood flow

Percent changes in cerebral blood flow (D%CBF, graph A), arterial oxygen content (Cao2, graph B), and cerebral oxygen delivery (CDO2, graph C) with time at high-altitude from seven studies at various altitudes and durations. Severinghaus et al. (1966) studied CBF using the Kety-Schmidt technique in five subjects brought rapidly by car to 3810 m. Using the Xe133 method, Jensen et al. (1990) measured CBF in 12 subjects at 3475 m. Huang et al. (1987) measured ICA and VA blood velocities as a metric of CBF on Pikes Peak (4300 m). Baumgartner et al. (1994) studied 24 subjects who rapidly ascended to 3200m by cable car, slept one night at 3600 m, and ascended by foot to 4559m the next day. Cerebral blood flow was estimated by transcranial Doppler ultrasound. About two-thirds of the subjects developed symptoms of AMS, data included are the mean of all subjects. Lucas et al. (2011) employed an 8–9 day ascent to 5050m and estimated changes in CBF by transcranial Doppler ultrasound of the middle cerebral artery. Willie et al. (2013) following the same ascent measured flow (Duplex ultrasound; and TCCD) in the ICA and VA and estimated global flow from: 2*ICA + 2* VA. The same methodological approach was used time Subudhi upon rapid ascent via car and oxygen breathing to 5240 m (Subudhi et al. 2013). Cao2 was calculated from: (1.39 · [Hb] · SaO2) + Pao2 *0.003. In some studies [Hb] data were not available, and typical data from previous studies over comparable time at related elevation were used. In other studies, Pao2 was not always reported; therefore, Sao2 was used to estimate Pao2 via (Severinghaus, 1979).

Only two studies have measured serial changes in CBF during progressive ascent to high altitude, but the findings may help explain small discrepancies between studies. In 2011, Wilson et al. (2011) measured diameter and velocity in the MCA (using transcranial color-coded Duplex-ultrasound, TCCD) following partial acclimation to 5300m (n = 24), 6400 m (n = 14), and 7950m (n = 5). Remarkable elevations (200%) in flow in the MCA occurred at 7950 m. Notably, the authors estimated *24% dilation of the MCA occurred at 6400 m. Dilation of the MCA further increased to *90% at 7950m (Fig.) and was rapidly reversed with oxygen supplementation (Fig.). Cerebral oxygen delivery and oxygenation were maintained by commensurate elevations of CBF even at these extreme altitudes. In another recent study, CBF and MCA diameter were measured at 1338 m, 3440 m, 4371 m, and over time at 5050 m (Willie et al., 2013). Dilation of the MCA was observed upon arrival at 5050 m with subsequent normalization of CBF and MCA diameter by days 10–12. Such findings are consistent with unchanged diameter following 17 days at 5400m (Wilson et al., 2011). It is important to note that according to Poiseuille’s Law, flow is proportional to radius raised to the fourth power. Therefore, consistent with previous concerns about TCD (Giller, 2003), that the MCA dilates at such levels of hypoxemia indicates that previous studies using TCD at altitude may have underestimated flow (see previous Fig.) and thus may explain differences between studies. These findings are particularly important because they suggest regional regulation of CBF occurs in both large and small cerebral arteries.

Changes in blood flow in the middle cerebral artery (MCA) upon progressive ascent to 7950 m

Changes in blood flow in the middle cerebral artery (MCA) upon progressive ascent to 7950 m. Data were collected following partial acclimation to 5300 m (n = 24), at 6400 m (n = 14), and at 7950 m (n = 5). Remarkable elevations (200%) in flow in the MCA occurred at 7950 m following removal of breathing supplementary oxygen and breathing air for 20 min. Dilation (*24%) of the MCA occurred at 6400 m, which was further increased to 90% at 7950 m. Oxygen supplementation at this highest altitude rapidly reversed the observed MCA vessel dilation (denoted by blue triangle). Elevations in CBF via cerebral vasodilation were adequate to maintain oxygen delivery, even at these extreme altitudes. Modified from Wilson et al. (2011).

Summary of the major factors acting to increase ( plus) and decrease (minus) CBF during exposure to hypoxia

Summary of the major factors acting to increase ( plus) and decrease (minus) CBF during exposure to hypoxia. Cao2, arterial oxygen content; CBV, cerebral blood volume; EDHF, endothelium-derived hyperpolarizing factor; ET-1, endothelin-1; HCT, hematocrit; NO, nitric oxide; O2-, superoxide; PGE, prostaglandins; SNA, sympathetic nerve activity; VAH, ventilatory acclimatization to hypoxia/altitude. Modified from Ainslie and Ogoh (2010); Ainslie et al. (2014).

It is clear that many aspects of CBF regulation and brain function at high altitude warrant further investigation. Indeed, several questions remain. For example, over the period of ventilatory acclimatization (weeks to months), how do interactions between the hypoxic ventilatory response, hypercapnic ventilatoy response, hypoxic cerebral vasodilatation, and hypocapnic cerebral vasoconstriction interact to alter CBF? Furthermore, what is the role of NO and/or adenosine in mediating cerebral vasodilation at high altitude? And last, what is the time-course of recovery in CBF following descent to sea level?

Cognitive Impairments at High Altitudes and Adaptation

Xiaodan Yan
High Alt Med Biol. 15:141–145, 2014
http://dx.doi.org:/10.1089/ham.2014.1009

High altitude hypoxia has been shown to have significant impact on cognitive performance. This article reviews the aspects in which, and the conditions under which, decreased cognitive performance has been observed at high altitudes. Neural changes related to high altitude hypoxia are also reviewed with respect to their possible contributions to cognitive impairments. In addition, potential adaptation mechanisms are reviewed among indigenous high altitude residents and long-term immigrant residents, with discussions about methodological concerns related to these studies.

The amount of cognitive impairments at high altitudes is related to the chronicity of exposure. Acute exposure usually refers to a duration of several weeks, whereas chronic exposure usually refer to ‘‘extended permanence’’ in the high altitude environment (Virue´s-Ortega and others, 2004). The altitude of ascending or residence is another factor affecting the severity of impairments. This review will first summarize the cognitive impairments in acute exposure, then talk about impairments in chronic exposure, with discussions about the effect of altitudes in corresponding sections.

High altitude-related neurocognitive impairments with ascending altitudes

High altitude-related neurocognitive impairments with ascending altitudes in acute high altitude exposure (Wilson and others, 2009).

human brain consumes about 20% of the total oxygen intake

The human brain consumes about 20% of the total oxygen intake, which is disproportional to its size (about 2% of the total body weight). In this figure, oxygen consumption is reflected from glucose consumption in positron emission tomography (PET) (Alavi and Reivich, 2002).

The possibility of adaptation to high altitude hypoxia has always been an intriguing issue. In the acute cases, the human body does have some capacity for acclimatization, which varies significantly for different individuals. The question is, in chronic cases, for example, does growing up at high altitude regions guarantee sufficient adaption to occur to compensate for the risk of cognitive impairments? Existing research tends to suggest that, although some level of adaptation does occur, neural and cognitive impairments are still observed in these populations who are native or long-term residents at high altitude.

Although multiple studies have suggested that growing up at high altitudes is associated with cognitive impairments, it is not to say that adaptation does not happen with prolonged chronic exposure to high altitudes. One study has revealed that as a function of the length of low altitude residence (across the range of 1–5 years), some neuroimaging parameters of original highlanders who grew up at high altitude regions had shown the trend of converging towards the patterns of original low altitude residents, although such changes were not accompanied by statistically significant changes in cognitive performance (Yan and others, 2010). It is possible that, given sufficiently long time for normoxia adaptation, the neural and cognitive impairments associated with high altitude hypoxia may be alleviated to a certain extent.

In summary, various cognitive impairments associated with high altitude hypoxia have been reported from existing studies, which are accompanied by findings about neural impairments, suggesting that these cognitive impairments have legitimate neural basis. The specific relationships between physiological symptoms and cognitive impairments appear to be complicated and require further elucidation. There are cognitive impairments associated with both acute and chronic exposure to high altitudes; however, particular caution should be taken when interpreting the findings about cognitive impairments among native high altitude residents because of the differences
in cultural and socioeconomic factors. Existing studies have suggested that there can be some level of adaptation to high altitudes, in spite of the fact that some neuronal impairment may be irreversible.

Exercise Capacity and Selected Physiological Factors by Ancestry and Residential Altitude: Cross-Sectional Studies of 9–10-Year-Old Children in Tibet

Bianba, Sveinung Berntsen, Lars Bo Andersen, Hein Stigum, et al.
High Alt Med Biol. 2014; 15:162–169
http://dx.doi.org:/10.1089/ham.2013.1084

Aim: Several physiological compensatory mechanisms have enabled Tibetans to live and work at high altitude, including increased ventilation and pulmonary diffusion capacity, both of which serve to increase oxygen transport in the blood. The aim of the present study was to compare exercise capacity (maximal power output) and selected physiological factors (arterial oxygen saturation and heart rate at rest and during maximal exercise, resting hemoglobin concentration, and forced vital capacity) in groups of native Tibetan children living at different residential altitudes (3700 vs. 4300 m above sea level) and across ancestry (native Tibetan vs. Han Chinese children living at the same altitude of 3700 m). Methods: A total of 430 9–10-year-old native Tibetan children from Tingri (4300 m) and 406 native Tibetan and 406 Han Chinese immigrants (77% lowland-born and 33% highland-born) from Lhasa (3700 m) participated in two cross-sectional studies. The maximal power output (Wmax) was assessed using an ergometer cycle. Results: Lhasa Tibetan children had a 20% higher maximal power output (watts/kg) than Tingri Tibetan and 4% higher than Lhasa Han Chinese. Maximal heart rate, arterial oxygen saturation at rest, lung volume, and arterial oxygen saturation were significantly associated with exercise capacity at a given altitude, but could not fully account for the differences in exercise capacity observed between ancestry groups or altitudes. Conclusions: The superior exercise capacity in native Tibetans vs. Han Chinese may reflect a better adaptation to life at high altitude. Tibetans at the lower residential altitude of 3700 m demonstrated a better exercise capacity than residents at a higher altitude of 4300m when measured at their respective residential altitudes. Such altitude- or ancestry-related difference could not be fully attributed to the physiological factors measured.

Group size effects on foraging and vigilance in migratory Tibetan antelope

Xinming Lian, Tongzuo Zhang, Yifan Cao, Jianping Su, Simon Thirgood
Behavioural Processes 76 (2007) 192–197
http://dx.doi.org:/10.1016/j.beproc.2007.05.001

Large group sizes have been hypothesized to decrease predation risk and increase food competition. We investigated group size effects on vigilance and foraging behavior during the migratory period in female Tibetan antelope Pantholops hodgsoni, in the Kekexili Nature Reserve of Qinghai Province, China. During June to August, adult female antelope and yearling females gather in large migratory groups and cross the Qinghai–Tibet highway to calving grounds within the Nature Reserve and return to Qumalai county after calving. Large groups of antelope aggregate in the migratory corridor where they compete for limited food resources and attract the attention of mammalian and avian predators and scavengers. We restricted our sampling to groups of less than 30 antelopes and thus limit our inference accordingly. Focal-animal sampling was used to record the behavior of the free-ranging antelope except for those with lambs. Tibetan antelope spent more time foraging in larger groups but frequency of foraging bouts was not affected by group size. Conversely, the time spent vigilant and frequency of vigilance bouts decreased with increased group size. We suggest that these results are best explained by competition for food and risk of predation.

High altitude exposure alters gene expression levels of DNA repair enzymes, and modulates fatty acid metabolism by SIRT4 induction in human skeletal muscle

Zoltan Acsa, Zoltan Boria, Masaki Takedaa, Peter Osvatha, et al.
Respiratory Physiology & Neurobiology 196 (2014) 33–37
http://dx.doi.org/10.1016/j.resp.2014.02.006

We hypothesized that high altitude exposure and physical activity associated with the attack to Mt Everest could alter mRNA levels of DNA repair and metabolic enzymes and cause oxidative stress-related challenges in human skeletal muscle. Therefore, we have tested eight male mountaineers (25–40 years old) before and after five weeks of exposure to high altitude, which included attacks to peaks above 8000 m. Data gained from biopsy samples from vastus lateralis revealed increased mRNA levels of both cytosolic and mitochondrial superoxide dismutase. On the other hand 8-oxoguanine DNA glycosylase(OGG1) mRNA levels tended to decrease while Ku70 mRNA levels and SIRT6 decreased with altitude exposure. The levels of SIRT1 and SIRT3 mRNA did not change significantly. But SIRT4 mRNA level increased significantly, which could indicate decreases in fatty acid metabolism, since SIRT4 is one of the important regulators of this process. Within the limitations of this human study, data suggest that combined effects of high altitude exposure and physical activity climbing to Mt. Everest, could jeopardize the integrity of the particular chromosome.

High-altitude adaptations in vertebrate hemoglobins

Roy E. Weber
Respiratory Physiology & Neurobiology 158 (2007) 132–142
http://dx.doi.org:/10.1016/j.resp.2007.05.001

Vertebrates at high altitude are subjected to hypoxic conditions that challenge aerobic metabolism. O2 transport from the respiratory surfaces to tissues requires matching between theO2 loading and unloading tensions and theO2-affinity of blood, which is an integrated function of hemoglobin’s intrinsic O2-affinity and its allosteric interaction with cellular effectors (organic phosphates, protons and chloride). Whereas short-term altitudinal adaptations predominantly involve adjustments in allosteric interactions, long-term, genetically-coded adaptations typically involve changes in the structure of the hemoglobin molecules. The latter commonly comprise substitutions of amino acid residues at the effector binding sites, the heme protein contacts, or at inter-subunit contacts that stabilize either the low-affinity (‘Tense’) or the high-affinity (‘Relaxed’) structures of the molecules. Molecular heterogeneity (multiple iso-Hbs with differentiated oxygenation properties) can further broaden the range of physico-chemical conditions where Hb functions under altitudinal hypoxia. This treatise reviews the molecular and cellular mechanisms that adapt hemoglobin-oxygen affinities in mammals, birds and ectothermic vertebrates at high altitude.

Vertebrate animals display remarkable ability to tolerate high altitudes and cope with the concomitant decreases in O2 tension that potentially constrain aerobic life (Monge and Leon-Velarde, 1991;Weber, 1995; Samaja et al., 2003). Compared to an ambient PO2 of approximately 160 mm Hg at sea level, inspired tension approximates only 95 mm Hg for llamas and frogs from Andean habitats above 4000 m, 45 mm Hg for bar-headed geese that fly across the Himalayas, and 33 mm Hg for Ruppell’s griffon that soars at 11,300 m over Africa’s Ivory Coast. Apart from the distinct adaptations manifest in blood’s O2-transporting properties, tolerance to decreased O2 availability may entail reconfigurations at the organ and cellular levels that include a switch to partial anaerobiosis. Driven by needs to reduce aerobic metabolic rate and maintain functional integrity (Ramirez et al., 2007), these pertain to a core triad of adaptations:

metabolic suppression,
tolerance to metabolite (e.g. lactate) accumulation, and
defenses against increased free radicals associated with return to high O2 tensions (Bickler and Buck, 2007).

The response to oxygen lack comprises two phases

defense, which includes metabolic arrest (a suppression of ATP-demand and ATP-supply) and channel arrest (decreases cell membrane permeability), and
rescue, which commonly involves preferential expression of proteins that are implicated in extending metabolic down-regulation (Hochachka et al., 1996).

These responses vary greatly in different species and different tissues. Thus, although mixed-venous lactate concentrations increase strongly in sea-level as well as high-altitude acclimated pigeons that are exposed to altitude (from 1–2 mM at sea level to 5–7 mM at 9000 m) (Weinstein et al., 1985), and humans performing submaximal work at high altitude show a transient ‘lactate paradox’ (lower peak lactate levels that humans living at sea level (Lundby et al., 2000)), many species do not exhibit altitude-related changes in anaerobic metabolism.

Organismic adaptations to survive and perform physical exercise at extreme altitudinal hypoxia are diverse. In birds the undisputed high-altitude champions, where flapping flight may raise the energy demand 10–20-fold compared to resting levels (Scott et al., 2006), a highly efficient “cross-current” ventilation perfusion arrangement in the lungs may increase arterial O2 tensions above the tensions in expired air (Scheid, 1979) and drastically reduce the difference between inhalant and arterial O2 tensions (to 1 mm Hg in bar-headed geese subjected to simulated altitude of 11580 m) (Black and Tenney, 1980). The Andean frog Telmatobius culeus has a highly ‘oversized’ (folded) and vascularized skin that is ventilated by ‘bobbing’ behavior to support water(=skin) breathing. Manifold organismic adaptations moreover include combinations of increased muscle Mb concentrations (Reynafarje and Morrison, 1962) increased muscle capillarization (manifest in mammals and birds (cf. Monge et al., 1991)) and decreased red cell size (seen in amphibians but not high-altitude reptiles (Ruiz et al., 1989; Ruiz et al., 1993)). Amphibians exhibit an interspecific correlation between erythrocyte count and the degree of vascularization of respiratory surfaces and muscle tissues (Hutchison and Szarski, 1965), that reflect differences in their ability to tolerate altitudinal hypoxia.

A sensitivity analysis of the factors that may limit exercise performance identifies high Hb-O2 affinity, together with high total ventilation and high tissue diffusion capacity as the physiological traits that have greatest adaptive benefit for bird flight at extreme high altitude (Scott and Milsom, 2006). Blood O2 affinity is a combination of the intrinsic O2 affinity of the ‘stripped’ (purified) Hb molecules and the interaction of allosteric effectors (like organic phosphates, protons and chloride ions) that decrease Hb-O2 affinity inside the rbcs (Weber and Fago, 2004). Short-term adaptations in O2 affinity are commonly mediated by changes in erythrocytic effectors such as organic phosphates (2,3-diphosphoglycerate, DPG, in mammals, inositol pentaphosphate, IPP, in birds, ATP in reptiles, and ATP and DPG in amphibians), whereas long-term adaptations (that include interspecific ones that are genetically determined) commonly involve changes in Hb structure (amino acid exchanges) that alter Hb’s intrinsic O2 affinity or its sensitivity to allosteric effectors.

Vertebrate Hbs are tetrameric molecules composed of two α (or α-like) chains and two β (or β-like) chains, which in humans consist of 141 and 146 amino acid residues, respectively. Each subunit exhibits a highly characteristic “globin fold” comprised of seven or eight α-helices (labelled A, B, C, etc.) linked by nonhelical (EF, FG) segments, and N- and C-terminal extensions termed NA and HC, respectively. Individual amino acid residues are identified by their sequential positions in chain or/and the helix; thus α1131(H14)-Ser refers to Serine that is the 131^st residue of α1 chain and the 14th of the H. During (de-) oxygenation Hb switches between two major structural states:

the high affinity oxygenated R (relaxed) state that prevails at the respiratory surfaces, and
the low affinity, deoxygenated T (tense) state that occurs predominantly in the tissues and is constrained by additional hydrogen bonds and salt bridges.

The Hbs exhibit cooperative homotropic interactions between the O2 binding heme groups (that cause the S-shaped O2 equilibrium curves and increase O2 loading and unloading for a given change in O2 tension) as well as inhibitory, heterotropic interactions between the hemes and the binding sites of effectors that decrease O2 affinity (increase the half-saturation O2 loading tension, P50) and facilitate O2 unloading.

A comparison of Hbs from different species (cf. Perutz, 1983) reveals that variation in the sensitivities to effectors correlates generally with exchanges of very few of the approximately 287 amino acid residues that comprise each αβ dimer. Thus in adult human Hb (HbA) at physiological pH, the majority of the Bohr effect (pH dependence of Hb-O2 affinity that facilitates O2 release in relatively acid working muscles) results from proton binding at the C-terminal residues of the β-chains (β146-His) (cf. Lukin and Ho, 2004). Correspondingly DPG binds to only four β-chain residues (β1-Val, β2-His, β82-Lys and β143-His), CO2 binding (carbamate formation) occurs at the uncharged amino-termini of both chains (α1-Val and β1-Val), and monovalent anions like chloride are considered to bind at one α-chain site (between α1-Val and α131–Ser) and one β-chain site (between β82-Lys and β1-Val) (cf. Riggs, 1988).

The small number of sites that primarily determine Hb-O2 affinity and its sensitivity to effectors aligns with the neutral theory of molecular evolution (Kimura, 1979), which holds that the majority of amino acid substitutions are non-adaptive and harmless—and facilitates identification of key molecular mechanisms implicated in adaptations at altitude.

The role of effectors in altitude adaptation is aptly illustrated in humans where Hb structure (intrinsic O2 affinity) remains unchanged. Newcomers and permanent residents at moderate altitude (e.g. 2000 m) show increased DPG levels, resulting in a decreased O2 affinity that positions arterial and mixed venous O2 tensions on the steep part of the O2 equilibrium curve, increasing O2 capacitance ([1]bO2) and O2 transport, without materially compromising O2 loading (Turek et al., 1973; Mairbaurl, 1994). The increased DPG correlates with erythropoietin-mediated formation of new rbcs that have higher glycolytic rates and higher DPG and ATP levels than old rbcs. However, faster increases in P50 than in DPG level indicate contributions from other factors, such as chloride and ATP, and Mg ions that neutralize the anionic effectors (Mairbaurl et al., 1993). At higher altitudes (4559 m) increased hyperventilation that drives off CO2 causes respiratory alkalosis (Mairbaurl, 1994). The higher pH increases O2 affinity via the Bohr effect and, offsetting the effect of increased DPG, leads to a similar O2 affinity and arterio-venous O2 saturation difference as at sea level (Fig.). O2 unloading in the tissues is moreover enhanced by metabolic acidification of capillary blood (Fig.).

Obviously right-shifted curves (that favor O2 unloading) becomes counterproductive at extreme altitudes where O2 loading becomes compromised, predicting that decreased O2 affinity becomes maladaptive under severe hypoxic stress. This is consistent with the observation that a carbamylation-induced increase in blood O2 affinity of rats (that lowers P50 from 27 to 15 mm Hg), increases survival under hypobaric hypoxia equivalent to 9200 meters’ altitude (Eaton et al., 1974). The altitude limit where increased affinity rather than a decreased affinity optimizes tissue O2 supply < 5000 m in man (Samaja et al., 2003)] depends on organismic adaptations (e.g. efficiency of gas exchange) and thus will vary between species. Mammals that permanently inhabit high altitudes and show high blood O2 affinities include the Andean rodent Chinchilla brevicaudata living at 3000–5000 m (blood P50 = 23 mm Hg compared to 38 mm Hg in the rat) (Ostojic et al., 2002). The deer mouse, Peromyscus maniculatus that occurs continuously from sea level to altitudes above 4300 m shows a strong correlation between blood O2 affinity and native altitude (Snyder et al., 1988). That genetically based differences in cofactor levels may contribute to this relationship follows from lower DPG/Hb ratios found in specimens resident, and native to, high altitude than in those from low altitude, after long-term acclimation of both groups to low altitude (Snyder, 1982).

O2 equilibrium curves of human blood illustrating the effects of increases in red cell DPG and pH at high-altitude

O2 equilibrium curves of human blood illustrating the effects of increases in red cell DPG and pH at high-altitude (4559 m). Solid curves refer to arterial blood (P50 = 26 mm,upper section) and cubical venous blood (P50 = 27.5 mm Hg, lower section); their displacement reflects the Bohr effect. The broken curves depict effects of increased DPG levels (↑DPG) at unchanged pH, increased pH (↑pH) at unchanged DPG, and of decreased tissue pH (↓pH) resulting from higher degrees of metabolic acidification in the tissues. Open and shaded vertical columns indicate O2 unloaded at sea level and 4559 m, respectively, for venous O2 tensions (PvO2) of 25 and 15 mm Hg,respectively [Modified after (Mairbaurl, 1994)].

Camelids. The high blood-O2 affinities in Andean camelids (llama, vicunia, alpaca and guanaco) whose natural habitats exceed 3000 m (Bartels et al., 1963) compared to those of similarly-sized lowland mammals are well-established. In the camelids a β2His→Asn substitution deletes two of the seven DPG contacts in the tetrameric Hb, which increases blood O2 affinity by reducing the DPG effect. Although the intrinsic Hb-O2 affinity is lower in llama than in the related, lowland camel (Bauer et al., 1980), llama blood has a higher O2 affinity due to a three-fold lower DPG-binding than in camel Hb that has the same DPG binding sites as humans (Bauer et al., 1980). In vicunia, a higher O2 affinity than in llama (that has identical β-chains), correlates with the α130Ala→Thr substitution, which introduces a hydroxyl polar group that predictably reduces the chloride binding at adjacent α131Asn residue .

Sheep and goats commonly express two isoforms, HbA and HbB. The heterogeneity is controlled by two autosomal alleles with codominant expression. Whereas individuals expressing HbA have higher blood-O2 affinity than those that express HbB, heterozygotes that express both forms at equimolar concentrations in the same erythrocytes show intermediate affinity. Anemic blood loss induces switching from HbA to HbC that has a similarly high affinity. Hbs A, B and C have identical α-chains but different β[1]-chains. It appears unknown whether altitudinal exposure (which like anemia, induces tissue hypoxia) modulates Hb heterogeneity via selective expression of specific β-chains.

Compared to most mammals that possess one major adult and one major fetal Hb, yak, Poephagus (=Bos) grunniens, a native to altitudes of 3000–6000 m in Tibet, Nepal and Bhutan, has two or four major adult Hbs and two major fetal Hbs. These Hbs exhibit higher intrinsic affinities than closely-related bovine Hb, marked DPG sensitivities and, exceptional amongst mammals, differentiated O2 affinities that indicates an extended range of ambient O2 tensions (and altitudes) in which the composite Hb functions.

(Not shown). Representation of interchain contacts considered to underly differentiated O2 affinities in Rueppell’s griffon isoHbs A, A , D and D that have identical β- chains but different α- chains. Accordingly the van der Waal’s contact between β134Ile and β₁125-Asp in Hbs A , D and D stabilizes the low-affinity, T-state less strongly than the H-bond between Thr 134 and β₁125-Asp and thus increases O2 affinity in Hbs A, D and D. Analogously, the hydrogen bonds between α₁38-β₂97/99 that stabilize the high-affinity oxystructure (raising O2 affinity in isoHbs D and D) cannot form in HbA and HbA that have Pro at α₁38.

Ostriches, the largest extant birds, exhibit a β2His→Gln exchange (that reduces phosphate interaction). They moreover ‘use’ ITP (inositol phosphate) that carries fewer negative charges, and predictably has lesser allosteric effect, than IPP (Isaacks et al., 1977), predicting a high blood O2 affinity that is compatible with ‘scaling’ and (as in elephants) increases high altitude tolerance.

Whereas some adult birds express one major iso-Hb (HbA), the majority of species, reportedly all that fly at high altitudes (Hiebl et al., 1987), also express a less abundant HbD. HbD has the same β-chains as HbA but different α-chains (α^D) and exhibits higher O2 affinities (Huisman et al., 1964). There is no consistent evidence for hypoxia-induced changes in HbD expression.

An example of how “molecular anatomy is just as key to understanding molecular adaptation as phylogeny and physiological ecology” (Golding and Dean, 1998) is Hb of the high-altitude tolerant bar-headed goose that has a sharply higher blood O2 affinity than that of the closely related graylag goose that is restricted to lower altitudes (P50 = 29.7 and 39.5mmHg at 37 ◦C and pH 7.4). The Hbs differ by only four (greylag→bar-headed) amino acid exchanges: α18Gly→Ser, α63Ala→Val, β125Glu→Asp and α119Pro→Ala. The last mentioned exchange that is unique in birds, predictably increases O2 affinity, by deleting a contact between α₁119 and β₁55 that destabilizes the T-structure (Perutz, 1983). Moreover, Andean ‘goose’ Hb that also has high blood O2 affinity shows β55 Leu→Ser that deletes the same contact. Significantly, two human Hb mutants (α₁19Pro–Ala and β₁55Met→Ser) engineered by site-directed mutagenesis to mimic the mutations found in bar-headed and Andean geese possess markedly higher O2 affinities than native HbA.

Although “the study of molecular adaptation has long been fraught with difficulties not the least of which is identifying out the hundreds of amino acid replacements, those few directly responsible for major adaptations” Hb’s adaptations to high altitude are a prime example of how “an amino acid replacement of modest effect at the molecular level causes a dramatic expansion in an ecological niche” [quotations from (Golding et al., 1998)].

However, the pathway of molecular O2 from the respiratory medium to the cellular combustion sites via the Hb molecules is regulated by a symphony of supplementary adaptations that span different levels of biological organization, each of which (according to the principle of symmorphosis) may become maximally recruited in extreme cases (as in birds actively flying above 10,000 m). Apart from hyperventilation, that appears to occur ubiquitously (and increases blood O2 affinity via increased pH), different species subjected to less extreme hypoxic stress utilize different adaptations among the arsenal of organismic, cellular and molecular strategies that favor efficient aerobic utilization of the scarce O2 available at high altitude. No clear correlations exist between the adaptive strategies recruited by different animals on the one hand, and their phylogenetic position, mode of life or ecological niches on the other. An overall limitation is that short-term adaptive adjustments in O2 affinity (that may occur within individual animals) necessarily involves rapid adaptive responses, such as changes in the levels of erythrocytic effectors, whereas the long-term acclimations that have accumulated in permanent high-altitude dwellers during evolutionary development.

Genetic Diversity of Microsatellite DNA Loci of Tibetan Antelope (Chiru, Pantholops hodgsonii) in Hoh Xil National Nature Reserve, Qinghai, China

Hui Zhou, Diqiang Li, Yuguang Zhang, Tao Yang, Yi Liu
J Genetics and Genomics (Formerly Acta Genetica Sinica) 2007; 34(7): 600-607

The Tibetan antelope (Pantholops hodgsonii), indigenous to China, became an endangered species because of considerable reduction both in number and distribution during the 20th century. Presently, it is listed as an AppendixⅠspecies by CITES and as CategoryⅠ by the Key Protected Wildlife List of China. Understanding the genetic diversity and population structure of the Tibetan antelope is significant for the development of effective conservation plans that will ensure the recovery and future persistence of this species. Twenty-five microsatellites were selected to obtain loci with sufficient levels of polymorphism that can provide in-formation for the analysis of population structure. Among the 25 loci that were examined, nine of them showed high levels of genetic diversity. The nine variable loci (MCM38, MNS64, IOBT395, MCMAI, TGLA68, BM1329, BMS1341, BM3501, and MB066) were used to examine the genetic diversity of the Tibetan antelope (n = 75) in Hoh Xil National Nature Reserve(HXNNR), Qinghai, China. The results obtained by estimating the number of population suggested that all the 75 Tibetan antelope samples were from the same population. The mean number of alleles per locus was 9.4 ± 0.5300 (range, 7–12) and the mean effective number of alleles was 6.519 ± 0.5271 (range, 4.676–9.169). The observed mean and expected heterozygosity were 0.844 ± 0.0133 (range, 0.791–0.897) and 0.838 ± 0.0132 (range, 0.786–0.891), respectively. Mean Polymorphism Information Content (PIC) was 0.818 ± 0.0158 (range, 0.753–0.881). The value of Fixation index (Fis) ranged from −0.269 to −0.097 with the mean of −0.163 ± 0.0197. Mean Shannon’s information index was 1.990 ± 0.0719 among nine loci (range, 1.660–2.315). These results provide baseline data for the evaluation of the level of genetic variation in Tibetan antelope, which will be important for the development of conservation strategies in future.

Expression profiling of abundant genes in pulmonary and cardiac muscle tissues of Tibetan Antelope (Pantholops hodgsonii)

Xiaomei Tong, Yingzhong Yang, Weiwei Wang, Zenzhong Bai, et al.
Gene 523 (2013) 187–191
http://dx.doi.org/10.1016/j.gene.2013.03.011

The Tibetan Antelope (TA), which has lived at high altitude for millions of years, was selected as the model species of high hypoxia-tolerant adaptation. Here we constructed two cDNA libraries from lung and cardiac muscle tissues, obtained EST sequences from the libraries, and acquired extensive expression data related energy metabolism genes. Comparative analyses of synonymous (Ks) and nonsynonymous (Ka) substitution rates of nucleus-encoded mitochondrial unigenes among different species revealed that many antelope genes have undergone rapid evolution. Surfactant-associated protein A (SP-A) and surfactant-associated protein B (SP-B) genes in the AT lineage experienced accelerated evolution compared to goat and sheep, and these two genes are highly expressed in the lung tissue. This study suggests that many specific genes of lung and cardiac muscle tissues showed unique expression profiles and may undergo fast adaptive evolution in TA. These data provide useful information for studying on molecular adaptation to high-altitude in humans as well as other mammals.

Exogenous Sphingosine-1-Phosphate Boosts Acclimatization in Rats Exposed to Acute Hypobaric Hypoxia: Assessment of Haematological and Metabolic Effects

Sonam Chawla, Babita Rahar, Mrinalini Singh, Anju Bansal, et al.
PLoS ONE 9(6): e98025. http://dx.doi.org:/10.1371/journal.pone.0098025

Background: The physiological challenges posed by hypobaric hypoxia warrant exploration of pharmacological entities to improve acclimatization to hypoxia. The present study investigates the preclinical efficacy of sphingosine-1-phosphate (S1P) to improve acclimatization to simulated hypobaric hypoxia. Experimental Approach: Efficacy of intravenously administered S1P in improving hematological and metabolic acclimatization was evaluated in rats exposed to simulated acute hypobaric hypoxia (7620 m for 6 hours) following S1P pre-treatment for three days. Major Findings: Altitude exposure of the control rats caused systemic hypoxia, hypocapnia (plausible sign of hyperventilation) and respiratory alkalosis due to suboptimal renal compensation indicated by an overt alkaline pH of the mixed venous blood. This was associated with pronounced energy deficit in the hepatic tissue along with systemic oxidative stress and inflammation. S1P pre-treatment improved blood oxygen-carrying-capacity by increasing hemoglobin, hematocrit, and RBC count, probably as an outcome of hypoxia inducible factor-1a mediated erythropoiesis and renal S1P receptor 1 mediated hemoconcentation. The improved partial pressure of oxygen in the blood could further restore aerobic respiration and increase ATP content in the hepatic tissue of S1P treated animals. S1P could also protect the animals from hypoxia mediated oxidative stress and inflammation. Conclusion: The study findings highlight S1P’s merits as a preconditioning agent for improving acclimatization to acute hypobaric hypoxia exposure. The results may have long term clinical application for improving physiological acclimatization of subjects venturing into high altitude for occupational or recreational purposes.

S1P Stabilizes HIF-1a and Boosts HIF-1a Mediated Hypoxia Adaptive Responses

S1P pre-conditioning led to 1.9 fold higher HIF-1a level in the kidney tissue (p<0.001) and 1.3 fold higher HIF-1a level in the liver tissue (p<0.001) in 1 mg/kg b.w. S1P group than in hypoxia control group. However, the hypoxia control group also had 1.3 folds higher HIF-1a levels in both liver and kidney tissues than in normoxia control groups, indicating a non-hypoxic boost of HIF-1a in S1P treated animals (Figure 1a and b). Further, plasma Epo levels were also observed to be significantly higher following S1P pre-treatment compared to the hypoxia control groups (p=0.05) (Figure 1a). Epo being primarily secreted by the kidneys and its expression being under regulation of HIF-1a, the raised plasma Epo level could be attributed to higher HIF-1a level in the kidney.

Figure 1. (not shown) Effect of S1P treatment on HIF-1a accumulation and downstream gene expression. a) Renal HIF-1a accumulation and Epo accumulation in plasma. HIF-1a accumulation in the renal tissue homogenate and build-up of erythropoietin in plasma was quantified. b) Hepatic HIF-1a accumulation. c) Effect S1P pre-treatment on circulatory VEGF. Vascular endothelial growth factor (VEGF) was quantified in plasma of experimental animals. These estimations were carried out using sandwich ELISA, and were carried out in triplicates for each experimental animal. Values are representative of mean 6 SD (n = 6). Statistical significance was calculated using ANOVA/post hoc Bonferroni. NC: Normoxia control, HC: Hypoxia control, 1: 1 mg S1P/kg b.w., 10: 10 mg S1P/kg b.w., 100: 100 mg S1P/kg b.w., p<0.05 compared with the normoxic control, p<0.01 compared with the normoxic control, p<0.001 compared with the normoxic control, p<0.05 compared with the hypoxic control, p<0.01 compared with the hypoxic control, p<0.001 compared with the hypoxic control. http://dx.doi.org:/10.1371/journal.pone.0098025.g001

Figure 2.(not shown) Effect of S1P treatment on S1P1 expression in renal tissue. Representative immune-blot of S1P1. Densitometric analysis of blot normalized against the loading control (α-tubulin). Values are representative of mean 6 SD (n = 6). Statistical significance was calculated using ANOVA/post hoc Bonferroni. NC: Normoxia control, HC: Hypoxia control, 1: 1 mg S1P/kg b.w., 10: 10 mg S1P/kg b.w., 100: 100 mg S1P/kg b.w., p<0.05 compared with the normoxic control, p<0.01 compared with the normoxic control, p<0.001 compared with the normoxic control, p< 0.05 compared with the hypoxic control, p<0.01 compared with the hypoxic control, p<0.001 compared with the hypoxic control. http://dx.doi.org:/10.1371/journal.pone.0098025.g002

Cloning of hypoxia-inducible factor 1α cDNA from a high hypoxia tolerant mammal—plateau pika (Ochotona curzoniae)

T.B. Zhao, H.X. Ning, S.S. Zhu, P. Sun, S.X. Xu, Z.J. Chang, and X.Q. Zhao
Biochemical and Biophysical Research Communications 316 (2004) 565–572
http://dx.doi.org:/10.1016/j.bbrc.2004.02.087

Hypoxia-inducible factor 1 is a transcription factor composed of HIF-1α and HIF-1β. It plays an important role in the signal transduction of cell response to hypoxia. Plateau pika (Ochotona curzoniae) is a high hypoxia-tolerant and cold adaptation species living only at 3000–5000m above sea level on the Qinghai-Tibet Plateau. In this study, HIF-1α cDNA of plateau pika was cloned and its expression in various tissues was studied. The results indicated that plateau pika HIF-1α cDNA was highly identical to those of the human (82%), bovine (89%), mouse (82%), and Norway rat (77%). The deduced amino acid sequence (822 bp) showed 90%, 92%, 86%, and 86% identities with those of the human, bovine, house mouse, and Norway rat, respectively. Northern blot analyses detected two isoforms named pLHIF-1α and pSHIF-1α. The HIF-1α mRNA was highly expressed in the brain and kidney, and much less in the heart, lung, liver, muscle, and spleen, which was quite different from the expression pattern of mouse mRNA. Meanwhile, a new variant of plateau pika HIF-1α mRNA was identified by RT-PCR and characterized. The deduced protein, composed of 536 amino acids, lacks a part of the oxygen-dependent degradation domain (ODD), both transactivation domains (TADs), and the nuclear localization signal motif (NLS). Our results suggest that HIF-1α may play an important role in the pika’s adaptation to hypoxia, especially in brain and kidney, and pika HIF-1α function pattern may be different from that of mouse HIF-1α. Furthermore, for the high ratio of HIF-1α homology among the animals, the HIF-1α gene may be a good phylogenetic performer in recovering the true phylogenetic relationships among taxa.

Comparative Proteomics Analyses of Kobresia pygmaea Adaptation to Environment along an Elevational Gradient on the Central Tibetan Plateau

Xiong Li, Yunqiang Yang, Lan Ma, Xudong Sun, et al.
PLoS ONE 9(6): e98410. http://dx.doi.org:/10.1371/journal.pone.0098410

Variations in elevation limit the growth and distribution of alpine plants because multiple environmental stresses impact plant growth, including sharp temperature shifts, strong ultraviolet radiation exposure, low oxygen content, etc. Alpine plants have developed special strategies to help survive the harsh environments of high mountains, but the internal mechanisms remain undefined. Kobresia pygmaea, the dominant species of alpine meadows, is widely distributed in the Southeastern Tibet Plateau, Tibet Autonomous Region, China. In this study, we mainly used comparative proteomics analyses to investigate the dynamic protein patterns for K. pygmaea located at four different elevations (4600, 4800, 4950 and 5100 m). A total of 58 differentially expressed proteins were successfully detected and functionally characterized. The proteins were divided into various functional categories, including material and energy metabolism, protein synthesis and degradation, redox process, defense response, photosynthesis, and protein kinase. Our study confirmed that increasing levels of antioxidant and heat shock proteins and the accumulation of primary metabolites, such as proline and abscisic acid, conferred K. pygmaea with tolerance to the alpine environment. In addition, the various methods K. pygmaea used to regulate material and energy metabolism played important roles in the development of tolerance to environmental stress. Our results also showed that the way in which K. pygmaea mediated stomatal characteristics and photosynthetic pigments constitutes an enhanced adaptation to alpine environmental stress. According to these findings, we concluded that K. pygmaea adapted to the high-elevation environment on the Tibetan Plateau by aggressively accumulating abiotic stress related metabolites and proteins and by the various life events mediated by proteins. Based on the species flexible physiological and biochemical processes, we surmised that environment change has only a slight impact on K. pygmaea except for possible impacts to populations on vulnerable edges of the species’ range
Altered mitochondrial biogenesis and its fusion gene expression is involved in the high-altitude adaptation of rat lung

Loganathan Chitra, Rathanam Boopathy
Respiratory Physiology & Neurobiology 192 (2014) 74– 84
http://dx.doi.org/10.1016/j.resp.2013.12.007

Intermittent hypobaric hypoxia-induced preconditioning (IHH-PC) of rat favored the adaption of lungs to severe HH conditions, possibly through stabilization of mitochondrial function. This is based on the data generated on regulatory coordination of nuclear DNA-encoded mitochondrial biogenesis; dynamics,and mitochondrial DNA (mtDNA)-encoded oxidative phosphorylation (mt-OXPHOS) genes expression. At16th day after start of IHH-PC (equivalent to 5,000 m, 6 h/d, 2 w of treatment), rats were exposed to severe HH stimulation at 9142 m for 6 h. The IHH-PC significantly counteracted the HH-induced effect of increased lung: water content; tissue damage; and oxidant injury. Further, IHH-PC significantly increased the mitochondrial number, mtDNA content and mt- OXPHOS complex activity in the lung tissues. This observation is due to an increased expression of genes involved in mitochondrial biogenesis (PGC-1α,ERRα, NRF1, NRF2 and TFAM), fusion (Mfn1 and Mfn2) and mt OXPHOS. Thus, the regulatory pathway formed by PGC-1α/ERRα/Mfn2 axes is required for the mitochondrial adaptation provoked by IHH-PC regimen to counteract subsequent HH stress.

Molecular characteristics of Tibetan antelope (Pantholops hodgsonii) mitochondrial DNA control region and phylogenetic inferences with related species

Feng, B. Fan, K. Li, Q.D. Zhang, et al.
Small Ruminant Research 75 (2008) 236–242
http://dx.doi.org:/10.1016/j.smallrumres.2007.06.011

Although Tibetan antelope (Pantholops hodgsonii) is a distinctive wild species inhabiting the Tibet-Qinghai Plateau, its taxonomic classification within the Bovidae is still unclear and little molecular information has been reported to date. In this study of Tibetan antelope, the complete control regions of mtDNA were sequenced and compared to those of Tibetan sheep (Ovis aries) and goat (Capra hircus). The length of the control region in Tibetan antelope, sheep and goat is 1067, 1181/1106 and 1121 bp, respectively. A 75-bp repeat sequence was found near the 5’ end of the control region of Tibetan antelope and sheep, the repeat numbers of which were two in Tibetan antelope and three or four in sheep. Three major domain regions, including HVI, HVII and central domain, in Tibetan antelope, sheep and goat were outlined, as well as other less conserved blocks, such as CSB-1, CSB-2, ETAS-1 and ETAS-2. NJ cluster analysis of the three species revealed that Tibetan antelope was more closely related to Tibetan sheep than Tibetan goat. These results were further confirmed by phylogenetic analysis using the partial control region sequences of these and 13 other antelope species. Tibetan antelope is better assigned to the Caprinae rather than the Antilopinae subfamily of the Bovidae.

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Neonatal Pathophysiology

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Neonatal Pathophysiology

Writer and Curator: Larry H. Bernstein, MD, FCAP

Introduction

This curation deals with a large and specialized branch of medicine that grew since the mid 20th century in concert with the developments in genetics and as a result of a growing population, with large urban populations, increasing problems of premature deliveries. The problems of prematurity grew very preterm to very low birth weight babies with special problems. While there were nurseries, the need for intensive care nurseries became evident in the 1960s, and the need for perinatal care of pregnant mothers also grew as a result of metabolic problems of the mother, intrauterine positioning of the fetus, and increasing numbers of teen age pregnancies as well as nutritional problems of the mother. There was also a period when the manufacturers of nutritional products displaced the customary use of breast feeding, which was consequential. This discussion is quite comprehensive, as it involves a consideration of the heart, the lungs, the brain, and the liver, to a large extent, and also the kidneys and skeletal development.

It is possible to outline, with a proportionate emphasis based on frequency and severity, this as follows:

Genetic and metabolic diseases
Nervous system
Cardiovascular
Pulmonary
Skeletal – bone and muscle
Hematological
Liver
Esophagus, stomach, and intestines
Kidneys
Immune system

Fetal Development

Gestation is the period of time between conception and birth when a baby grows and develops inside the mother’s womb. Because it’s impossible to know exactly when conception occurs, gestational age is measured from the first day of the mother’s last menstrual cycle to the current date. It is measured in weeks. A normal gestation lasts anywhere from 37 to 41 weeks.

Week 5 is the start of the “embryonic period.” This is when all the baby’s major systems and structures develop. The embryo’s cells multiply and start to take on specific functions. This is called differentiation. Blood cells, kidney cells, and nerve cells all develop. The embryo grows rapidly, and the baby’s external features begin to form.

Week 6-9: Brain forms into five different areas. Some cranial nerves are visible. Eyes and ears begin to form. Tissue grows that will the baby’s spine and other bones. Baby’s heart continues to grow and now beats at a regular rhythm. Blood pumps through the main vessels. Your baby’s brain continues to grow. The lungs start to form. Limbs look like paddles. Essential organs begin to grow.

Weeks 11-18: Limbs extended. Baby makes sucking motion. Movement of limbs. Liver and pancreas produce secretions. Muscle and bones developing.

Week 19-21: Baby can hear. Mom feels baby – and quickening.

http://www.nlm.nih.gov/medlineplus/ency/article/002398.htm

fetal-development

https://polination.files.wordpress.com/2014/02/abortion-new-research-into-fetal-development.jpg

Inherited Metabolic Disorders

The original cause of most genetic metabolic disorders is a gene mutation that occurred many, many generations ago. The gene mutation is passed along through the generations, ensuring its preservation.

Each inherited metabolic disorder is quite rare in the general population. Considered all together, inherited metabolic disorders may affect about 1 in 1,000 to 2,500 newborns. In certain ethnic populations, such as Ashkenazi Jews (Jews of central and eastern European ancestry), the rate of inherited metabolic disorders is higher.

Hundreds of inherited metabolic disorders have been identified, and new ones continue to be discovered. Some of the more common and important genetic metabolic disorders include:

Lysosomal storage disorders : Lysosomes are spaces inside cells that break down waste products of metabolism. Various enzyme deficiencies inside lysosomes can result in buildup of toxic substances, causing metabolic disorders including:

Hurler syndrome (abnormal bone structure and developmental delay)
Niemann-Pick disease (babies develop liver enlargement, difficulty feeding, and nerve damage)
Tay-Sachs disease (progressive weakness in a months-old child, progressing to severe nerve damage; the child usually lives only until age 4 or 5)
Gauchers disease and others

Galactosemia: Impaired breakdown of the sugar galactose leads to jaundice, vomiting, and liver enlargement after breast or formula feeding by a newborn.

Maple syrup urine disease: Deficiency of an enzyme called BCKD causes buildup of amino acids in the body. Nerve damage results, and the urine smells like syrup.

Phenylketonuria (PKU): Deficiency of the enzyme PAH results in high levels of phenylalanine in the blood. Mental retardation results if the condition is not recognized.

Glycogen storage diseases: Problems with sugar storage lead to low blood sugar levels, muscle pain, and weakness.

Metal metabolism disorders: Levels of trace metals in the blood are controlled by special proteins. Inherited metabolic disorders can result in protein malfunction and toxic accumulation of metal in the body:

Wilson disease (toxic copper levels accumulate in the liver, brain, and other organs)

Hemochromatosis (the intestines absorb excessive iron, which builds up in the liver, pancreas, joints, and heart, causing damage)

Organic acidemias: methylmalonic acidemia and propionic acidemia.

Urea cycle disorders: ornithine transcarbamylase deficiency and citrullinemia

Hemoglobinopathies – thalassemias, sickle cell disease

Red cell enzyme disorders – glucose-6-phosphate dehydrogenase, pyruvate kinase

This list is by no means complete.

http://www.webmd.com/a-to-z-guides/inherited-metabolic-disorder-types-and-treatments

New variations in the galactose-1-phosphate uridyltransferase (GALT) gene

Clinical and molecular spectra in galactosemic patients from neonatal screening in northeastern Italy: Structural and functional characterization of new variations in the galactose-1-phosphate uridyltransferase (GALT) gene

E Viggiano, A Marabotti, AP Burlina, C Cazzorla, MR D’Apice, et al.
Gene 559 (2015) 112–118
http://dx.doi.org/10.1016/j.gene.2015.01.013
Galactosemia (OMIM 230400) is a rare autosomal recessive inherited disorder caused by deficiency of galactose-1-phosphate uridyltransferase (GALT; OMIM 606999) activity. The incidence of galactosemia is 1 in 30,000–60,000, with a prevalence of 1 in 47,000 in the white population. Neonates with galactosemia can present acute symptoms, such as severe hepatic and renal failure, cataract and sepsis after milk introduction. Dietary restriction of galactose determines the clinical improvement in these patients. However, despite early diagnosis by neonatal screening and dietary treatment, a high percentage of patients develop long-term complications such as cognitive disability, speech problems, neurological and/or movement disorders and, in females, ovarian dysfunction.

With the benefit of early diagnosis by neonatal screening and early therapy, the acute presentation of classical galactosemia can be prevented. The objectives of the current study were to report our experience with a group of galactosemic patients identified through the neonatal screening programs in northeastern Italy during the last 30 years.

No neonatal deaths due to galactosemia complications occurred after the introduction of the neonatal screening program. However, despite the early diagnosis and dietary treatment, the patients with classical galactosemia showed one or more long-term complications.

A total of 18 different variations in the GALT gene were found in the patient cohort: 12 missense, 2 frameshift, 1 nonsense, 1 deletion, 1 silent variation, and 1 intronic. Six (p.R33P, p.G83V, p.P244S, p.L267R, p.L267V, p.E271D) were new variations. The most common variation was p.Q188R (12 alleles, 31.5%), followed by p.K285N (6 alleles, 15.7%) and p.N314D (6 alleles, 15.7%). The other variations comprised 1 or 2 alleles. In the patients carrying a new mutation, the biochemical analysis of GALT activity in erythrocytes showed an activity of < 1%. In silico analysis (SIFT, PolyPhen-2 and the computational analysis on the static protein structure) showed potentially damaging effects of the six new variations on the GALT protein, thus expanding the genetic spectrum of GALT variations in Italy. The study emphasizes the difficulty in establishing a genotype–phenotype correlation in classical galactosemia and underlines the importance of molecular diagnostic testing prior to making any treatment.

Diagnosis and Management of Hereditary Hemochromatosis

Reena J. Salgia, Kimberly Brown
Clin Liver Dis 19 (2015) 187–198
http://dx.doi.org/10.1016/j.cld.2014.09.011

Hereditary hemochromatosis (HH) is a diagnosis most commonly made in patients with elevated iron indices (transferrin saturation and ferritin), and HFE genetic mutation testing showing C282Y homozygosity.

The HFE mutation is believed to result in clinical iron overload through altering hepcidin levels resulting in increased iron absorption.

The most common clinical complications of HH include cirrhosis, diabetes, nonischemic cardiomyopathy, and hepatocellular carcinoma.

Liver biopsy should be performed in patients with HH if the liver enzymes are elevated or serum ferritin is greater than 1000 mg/L. This is useful to determine the degree of iron overload and stage the fibrosis.

Treatment of HH with clinical iron overload involves a combination of phlebotomy and/or chelation therapy. Liver transplantation should be considered for patients with HH-related decompensated cirrhosis.

Health economic evaluation of plasma oxysterol screening in the diagnosis of Niemann–Pick Type C disease among intellectually disabled using discrete event simulation

CDM van Karnebeek, Tima Mohammadi, Nicole Tsaod, Graham Sinclair, et al.
Molecular Genetics and Metabolism 114 (2015) 226–232
http://dx.doi.org/10.1016/j.ymgme.2014.07.004

Background: Recently a less invasive method of screening and diagnosing Niemann–Pick C (NP-C) disease has emerged. This approach involves the use of a metabolic screening test (oxysterol assay) instead of the current practice of clinical assessment of patients suspected of NP-C (review of medical history, family history and clinical examination for the signs and symptoms). Our objective is to compare costs and outcomes of plasma oxysterol screening versus current practice in diagnosis of NP-C disease among intellectually disabled (ID) patients using decision-analytic methods.
Methods: A discrete event simulation model was conducted to follow ID patients through the diagnosis and treatment of NP-C, forecast the costs and effectiveness for a cohort of ID patients and compare the outcomes and costs in two different arms of the model: plasma oxysterol screening and routine diagnosis procedure (anno 2013) over 5 years of follow up. Data from published sources and clinical trials were used in simulation model. Unit costs and quality-adjusted life-years (QALYs) were discounted at a 3% annual rate in the base case analysis. Deterministic and probabilistic sensitivity analyses were conducted.
Results: The outcomes of the base case model showed that using plasma oxysterol screening for diagnosis of NP-C disease among ID patients is a dominant strategy. It would result in lower total cost and would slightly improve patients’ quality of life. The average amount of cost saving was $3642 CAD and the incremental QALYs per each individual ID patient in oxysterol screening arm versus current practice of diagnosis NP-C was 0.0022 QALYs. Results of sensitivity analysis demonstrated robustness of the outcomes over the wide range of changes in model inputs.
Conclusion: Whilst acknowledging the limitations of this study, we conclude that screening ID children and adolescents with oxysterol tests compared to current practice for the diagnosis of NP-C is a dominant strategy with clinical and economic benefits. The less costly, more sensitive and specific oxysterol test has potential to save costs to the healthcare system while improving patients’ quality of life and may be considered as a routine tool in the NP-C diagnosis armamentarium for ID. Further research is needed to elucidate its effectiveness in patients presenting characteristics other than ID in childhood and adolescence.

Neurological and Behavioral Disorders

Estrogen receptor signaling during vertebrate development

Maria Bondesson, Ruixin Hao, Chin-Yo Lin, Cecilia Williams, Jan-Åke Gustafsson
Biochimica et Biophysica Acta 1849 (2015) 142–151
http://dx.doi.org/10.1016/j.bbagrm.2014.06.005

Estrogen receptors are expressed and their cognate ligands produced in all vertebrates, indicative of important and conserved functions. Through evolution estrogen has been involved in controlling reproduction, affectingboth the development of reproductive organs and reproductive behavior. This review broadly describes the synthesis of estrogens and the expression patterns of aromatase and the estrogen receptors, in relation to estrogen functions in the developing fetus and child. We focus on the role of estrogens for the development of reproductive tissues, as well as non-reproductive effects on the developing brain. We collate data from human, rodent, bird and fish studies and highlight common and species-specific effects of estrogen signaling on fetal development. Morphological malformations originating from perturbed estrogen signaling in estrogen receptor and aromatase knockout mice are discussed, as well as the clinical manifestations of rare estrogen receptor alpha and aromatase gene mutations in humans. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Memory function and hippocampal volumes in preterm born very-low-birth-weight (VLBW) young adults

Synne Aanes, Knut Jørgen Bjuland, Jon Skranes, Gro C.C. Løhaugen
NeuroImage 105 (2015) 76–83
http://dx.doi.org/10.1016/j.neuroimage.2014.10.023

The hippocampi are regarded as core structures for learning and memory functions, which is important for daily functioning and educational achievements. Previous studies have linked reduction in hippocampal volume to working memory problems in very low birth weight (VLBW; ≤1500 g) children and reduced general cognitive ability in VLBW adolescents. However, the relationship between memory function and hippocampal volume has not been described in VLBW subjects reaching adulthood. The aim of the study was to investigate memory function and hippocampal volume in VLBW young adults, both in relation to perinatal risk factors and compared to term born controls, and to look for structure–function relationships. Using Wechsler Memory Scale-III and MRI, we included 42 non-disabled VLBW and 61 control individuals at age 19–20 years, and related our findings to perinatal risk factors in the VLBW-group. The VLBW young adults achieved lower scores on several subtests of the Wechsler Memory Scale-III, resulting in lower results in the immediate memory indices (visual and auditory), the working memory index, and in the visual delayed and general memory delayed indices, but not in the auditory delayed and auditory recognition delayed indices. The VLBW group had smaller absolute and relative hippocampal volumes than the controls. In the VLBW group inferior memory function, especially for the working memory index, was related to smaller hippocampal volume, and both correlated with lower birth weight and more days in the neonatal intensive care unit (NICU). Our results may indicate a structural–functional relationship in the VLBW group due to aberrant hippocampal development and functioning after preterm birth.

The relation of infant attachment to attachment and cognitive and behavioural outcomes in early childhood

Yan-hua Ding, Xiu Xua, Zheng-yan Wang, Hui-rong Li, Wei-ping Wang
Early Human Development 90 (2014) 459–464
http://dx.doi.org/10.1016/j.earlhumdev.2014.06.004

Background: In China, research on the relation of mother–infant attachment to children’s development is scarce.
Aims: This study sought to investigate the relation of mother–infant attachment to attachment, cognitive and behavioral development in young children. Study design: This study used a longitudinal study design.
Subjects: The subjects included healthy infants (n=160) aged 12 to 18 months.
Outcome measures: Ainsworth’s “Strange Situation Procedure” was used to evaluate mother–infant attachment types. The attachment Q-set (AQS) was used to evaluate the attachment between young children and their mothers. The Bayley scale of infant development-second edition (BSID-II) was used to evaluate cognitive developmental level in early childhood. Achenbach’s child behavior checklist (CBCL) for 2- to 3-year-oldswas used to investigate behavioral problems.
Results: In total, 118 young children (73.8%) completed the follow-up; 89.7% of infants with secure attachment and 85.0% of infants with insecure attachment still demonstrated this type of attachment in early childhood (κ = 0.738, p b 0.05). Infants with insecure attachment collectively exhibited a significantly lower mental development index (MDI) in early childhood than did infants with secure attachment, especially the resistant type. In addition, resistant infants were reported to have greater social withdrawal, sleep problems and aggressive behavior in early childhood.
Conclusion: There is a high consistency in attachment development from infancy to early childhood. Secure mother–infant attachment predicts a better cognitive and behavioral outcome; whereas insecure attachment, especially the resistant attachment, may lead to a lower cognitive level and greater behavioral problems in early childhood.

representations of the HPA axis

representations of limbic stress-integrative pathways from the prefrontal cortex, amygdala and hippocampus

Fetal programming of schizophrenia: Select mechanisms

Monojit Debnatha, Ganesan Venkatasubramanian, Michael Berk
Neuroscience and Biobehavioral Reviews 49 (2015) 90–104
http://dx.doi.org/10.1016/j.neubiorev.2014.12.003

Mounting evidence indicates that schizophrenia is associated with adverse intrauterine experiences. An adverse or suboptimal fetal environment can cause irreversible changes in brain that can subsequently exert long-lasting effects through resetting a diverse array of biological systems including endocrine, immune and nervous. It is evident from animal and imaging studies that subtle variations in the intrauterine environment can cause recognizable differences in brain structure and cognitive functions in the offspring. A wide variety of environmental factors may play a role in precipitating the emergent developmental dysregulation and the consequent evolution of psychiatric traits in early adulthood by inducing inflammatory, oxidative and nitrosative stress (IO&NS) pathways, mitochondrial dysfunction, apoptosis, and epigenetic dysregulation. However, the precise mechanisms behind such relationships and the specificity of the risk factors for schizophrenia remain exploratory. Considering the paucity of knowledge on fetal programming of schizophrenia, it is timely to consolidate the recent advances in the field and put forward an integrated overview of the mechanisms associated with fetal origin of schizophrenia.

NMDA receptor dysfunction in autism spectrum disorders

Eun-Jae Lee, Su Yeon Choi and Eunjoon Kim
Current Opinion in Pharmacology 2015, 20:8–13
http://dx.doi.org/10.1016/j.coph.2014.10.007

Autism spectrum disorders (ASDs) represent neurodevelopmental disorders characterized by two core symptoms;

(1) impaired social interaction and communication, and
(2) restricted and repetitive behaviors, interests, and activities.

ASDs affect ~ 1% of the population, and are considered to be highly genetic in nature. A large number (~600) of ASD-related genetic variations have been identified (sfari.org), and target gene functions are apparently quite diverse. However, some fall onto common pathways, including synaptic function and chromosome remodeling, suggesting that core mechanisms may exist.

Abnormalities and imbalances in neuronal excitatory and inhibitory synapses have been implicated in diverse neuropsychiatric disorders including autism spectrum disorders (ASDs). Increasing evidence indicates that dysfunction of NMDA receptors (NMDARs) at excitatory synapses is associated with ASDs. In support of this, human ASD-associated genetic variations are found in genes encoding NMDAR subunits. Pharmacological enhancement or suppression of NMDAR function ameliorates ASD symptoms in humans. Animal models of ASD display bidirectional NMDAR dysfunction, and correcting this deficit rescues ASD-like behaviors. These findings suggest that deviation of NMDAR function in either direction contributes to the development of ASDs, and that correcting NMDAR dysfunction has therapeutic potential for ASDs.

Among known synaptic proteins implicated in ASD are metabotropic glutamate receptors (mGluRs). Functional enhancement and suppression of mGluR5 are associated with fragile X syndrome and tuberous sclerosis, respectively, which share autism as a common phenotype. More recently, ionotropic glutamate receptors, namely NMDA receptors (NMDARs) and AMPA receptors (AMPARs), have also been implicated in ASDs. In this review, we will focus on NMDA receptors and summarize evidence supporting the hypothesis that NMDAR dysfunction contributes to ASDs, and, by extension, that correcting NMDAR dysfunction has therapeutic potential for ASDs. ASD-related human NMDAR genetic variants.

Chemokines roles within the hippocampus

IL-1 mediates stress-induced activation of the HPA axis

A systemic model of the beneficial role of immune processes in behavioral and neural plasticity

Three Classes of Glutamate Receptors

Clinical studies on ASDs have identified genetic variants of NMDAR subunit genes. Specifically, de novo mutations have been identified in the GRIN2B gene, encoding the GluN2B subunit. In addition, SNP analyses have linked both GRIN2A (GluN2A subunit) and GRIN2B with ASDs. Because assembled NMDARs contain four subunits, each with distinct properties, ASD-related GRIN2A/ GRIN2B variants likely alter the functional properties of NMDARs and/or NMDAR-dependent plasticity.

Pharmacological modulation of NMDAR function can improve ASD symptoms. D-cycloserine (DCS), an NMDAR agonist, significantly ameliorates social withdrawal and repetitive behavior in individuals with ASD. These results suggest that reduced NMDAR function may contribute to the development of ASDs in humans.

We can divide animal studies into two groups. The first group consists of animals in which NMDAR modulators were shown to normalize both NMDAR dysfunction and ASD-like behaviors, establishing strong association between NMDARs and ASD phenotypes (Fig.). In the second group, NMDAR modulators were shown to rescue ASD-like behaviors, but NMDAR dysfunction and its correction have not been demonstrated.

ASD models with data showing rescue of both NMDAR dysfunction and ASD like behaviors Mice lacking neuroligin-1, an excitatory postsynaptic adhesion molecule, show reduced NMDAR function in the hippocampus and striatum, as evidenced by a decrease in NMDA/AMPA ratio and long-term potentiation (LTP). Neuroligin-1 is thought to enhance synaptic NMDAR function, by directly interacting with and promoting synaptic localization of NMDARs.

Fig not shown.

Bidirectional NMDAR dysfunction in animal models of ASD. Animal models of ASD with bidirectional NMDAR dysfunction can be positioned on either side of an NMDAR function curve. Model animals were divided into two groups.

Group 1: NMDAR modulators normalize both NMDAR dysfunction and ASD-like behaviors (green).

Group 2: NMDAR modulators rescue ASD-like behaviors, but NMDAR dysfunction and its rescue have not been demonstrated (orange). Note that Group 2 animals are tentatively placed on the left-hand side of the slope based on the observed DCS rescue of their ASD-like phenotypes, but the directions of their NMDAR dysfunctions remain to be experimentally determined.

ASD models with data showing rescue of ASD-like behaviors but no demonstrated NMDAR dysfunction

Tbr1 is a transcriptional regulator, one of whose targets is the gene encoding the GluN2B subunit of NMDARs. Mice haploinsufficient for Tbr1 (Tbr1+/-) show structural abnormalities in the amygdala and limited GluN2B induction upon behavioral stimulation. Both systemic injection and local amygdalar infusion of DCS rescue social deficits and impaired associative memory in Tbr1+/- mice. However, reduced NMDAR function and its DCS-dependent correction have not been demonstrated.

Spatial working memory and attention skills are predicted by maternal stress during pregnancy

André Plamondon, Emis Akbari, Leslie Atkinson, Meir Steiner
Early Human Development 91 (2015) 23–29
http://dx.doi.org/10.1016/j.earlhumdev.2014.11.004

Introduction: Experimental evidence in rodents shows that maternal stress during pregnancy (MSDP) negatively impacts spatial learning and memory in the offspring. We aim to investigate the association between MSDP (i.e., life events) and spatial working memory, as well as attention skills (attention shifting and attention focusing), in humans. The moderating roles of child sex, maternal anxiety during pregnancy and postnatal care are also investigated. Methods: Participants were 236mother–child dyads that were followed from the second trimester of pregnancy until 4 years postpartum. Measurements included questionnaires and independent observations.
Results: MSDP was negatively associated with attention shifting at 18monthswhen concurrent maternal anxiety was low. MSDP was associated with poorer spatial working memory at 4 years of age, but only for boys who experienced poorer postnatal care.
Conclusion: Consistent with results observed in rodents, MSDP was found to be associated with spatial working memory and attention skills. These results point to postnatal care and maternal anxiety during pregnancy as potential targets for interventions that aim to buffer children from the detrimental effects of MSDP.

Acute and massive bleeding from placenta previa and infants’ brain damage

Ken Furuta, Shuichi Tokunaga, Seishi Furukawa, Hiroshi Sameshima
Early Human Development 90 (2014) 455–458
http://dx.doi.org/10.1016/j.earlhumdev.2014.06.002

Background: Among the causes of third trimester bleeding, the impact of placenta previa on cerebral palsy is not well known.
Aims: To clarify the effect ofmaternal bleeding fromplacenta previa on cerebral palsy, and in particular when and how it occurs.
Study design: A descriptive study.
Subjects: Sixty infants born to mothers with placenta previa in our regional population-based study of 160,000 deliveries from 1998 to 2012. Premature deliveries occurring atb26 weeks of gestation and placenta accrete were excluded.
Outcome measures: Prevalence of cystic periventricular leukomalacia (PVL) and cerebral palsy (CP).
Results: Five infants had PVL and 4 of these infants developed CP (1/40,000 deliveries). Acute and massive bleeding (>500 g) within 8 h) occurred at around 30–31 weeks of gestation, and was severe enough to deliver the fetus. None of the 5 infants with PVL underwent antenatal corticosteroid treatment, and 1 infant had mild neonatal hypocapnia with a PaCO2 < 25 mm Hg. However, none of the 5 PVL infants showed umbilical arterial academia with pH < 7.2, an abnormal fetal heart rate monitoring pattern, or neonatal hypotension.
Conclusions: Our descriptive study showed that acute and massive bleeding from placenta previa at around 30 weeks of gestation may be a risk factor for CP, and requires careful neonatal follow-up. The underlying process connecting massive placental bleeding and PVL requires further investigation.

Impact of bilirubin-induced neurologic dysfunction on neurodevelopmental outcomes

Courtney J. Wusthoff, Irene M. Loe
Seminars in Fetal & Neonatal Medicine 20 (2015) 52e57
http://dx.doi.org/10.1016/j.siny.2014.12.003

Extreme neonatal hyperbilirubinemia has long been known to cause the clinical syndrome of kernicterus, or chronic bilirubin encephalopathy (CBE). Kernicterus most usually is characterized by choreoathetoid cerebral palsy (CP), impaired upward gaze, and sensorineural hearing loss, whereas cognition is relatively spared. The chronic condition of kernicterus may be, but is not always, preceded in the acute stage by acute bilirubin encephalopathy (ABE). This acute neonatal condition is also due to hyperbilirubinemia, and is characterized by lethargy and abnormal behavior, evolving to frank neonatal encephalopathy, opisthotonus, and seizures. Less completely defined is the syndrome of bilirubin-induced neurologic dysfunction (BIND).

Bilirubin-induced neurologic dysfunction (BIND) is the constellation of neurologic sequelae following milder degrees of neonatal hyperbilirubinemia than are associated with kernicterus. Clinically, BIND may manifest after the neonatal period as developmental delay, cognitive impairment, disordered executive function, and behavioral and psychiatric disorders. However, there is controversy regarding the relative contribution of neonatal hyperbilirubinemia versus other risk factors to the development of later neurodevelopmental disorders in children with BIND. In this review, we focus on the empiric data from the past 25 years regarding neurodevelopmental outcomes and BIND, including specific effects on developmental delay, cognition, speech and language development, executive function, and the neurobehavioral disorders, such as attention deficit/hyperactivity disorder and autism.

As noted in a technical report by the American Academy of Pediatrics Subcommittee on Hyperbilirubinemia, “it is apparent that the use of a single total serum bilirubin level to predict long-term outcomes is inadequate and will lead to conflicting results”. As described above, this has certainly been the case in research to date. To clarify how hyperbilirubinemia influences neurodevelopmental outcome, more sophisticated consideration is needed both of how to assess bilirubin exposure leading to neurotoxicity, and of those comorbid conditions which may lower the threshold for brain injury.

For example, premature infants are known to be especially susceptible to bilirubin neurotoxicity, with kernicterus reported following TB levels far lower than the threshold expected in term neonates. Similarly, among extremely preterm neonates, BBC is proportional to gestational age, meaning that the most premature infants have the highest UB, even for similar TB levels. Thus, future studies must be adequately powered to examine preterm infants separately from term infants, and should consider not just peak TB, but also BBC, as independent variables in neonates with hyperbilirubinemia. Similarly, an analysis by the NICHD NRN found that, among ELBW infants, higher UB levels were associated with a higher risk of death or NDI. However, increased TB levels were only associated with death or NDI in unstable infants. Again, UB or BBC appeared to be more useful than TB.

Are the neuromotor disabilities of bilirubin-induced neurologic dysfunction disorders related to the cerebellum and its connections?

Jon F. Watchko, Michael J. Painter, Ashok Panigrahy
Seminars in Fetal & Neonatal Medicine 20 (2015) 47e51
http://dx.doi.org/10.1016/j.siny.2014.12.004

Investigators have hypothesized a range of subcortical neuropathology in the genesis of bilirubin induced neurologic dysfunction (BIND). The current review builds on this speculation with a specific focus on the cerebellum and its connections in the development of the subtle neuromotor disabilities of BIND. The focus on the cerebellum derives from the following observations:
(i) the cerebellum is vulnerable to bilirubin-induced injury; perhaps the most vulnerable region within the central nervous system;
(ii) infants with cerebellar injury exhibit a neuromotor phenotype similar to BIND; and (iii) the cerebellum has extensive bidirectional circuitry projections to motor and non-motor regions of the brain-stem and cerebral cortex that impact a variety of neurobehaviors.
Future study using advanced magnetic resonance neuroimaging techniques have the potential to shed new insights into bilirubin’s effect on neural network topology via both structural and functional brain connectivity measurements.

Bilirubin-induced neurologic damage is most often thought of in terms of severe adverse neuromotor (dystonia with or without athetosis) and auditory (hearing impairment or deafness) sequelae. Observed together, they comprise the classic neurodevelopmental phenotype of chronic bilirubin encephalopathy or kernicterus, and may also be seen individually as motor or auditory predominant subtypes. These injuries reflect both a predilection of bilirubin toxicity for neurons (relative to glial cells) and the regional topography of bilirubin-induced neuronal damage characterized by prominent involvement of the globus pallidus, subthalamic nucleus, VIII cranial nerve, and cochlear nucleus.

It is also asserted that bilirubin neurotoxicity may be associated with other less severe neurodevelopmental disabilities, a condition termed “subtle kernicterus” or “bilirubin-induced neurologic dysfunction” (BIND). BIND is defined by a constellation of “subtle neurodevelopmental disabilities without the classical findings of kernicterus that, after careful evaluation and exclusion of other possible etiologies, appear to be due to bilirubin neurotoxicity”. These purportedly include:

(i) mild-to-moderate disorders of movement (e.g., incoordination, clumsiness, gait abnormalities, disturbances in static and dynamic balance, impaired fine motor skills, and ataxia); (ii) disturbances in muscle tone; and
(iii) altered sensorimotor integration. Isolated disturbances of central auditory processing are also included in the spectrum of BIND.

Cerebellar vulnerability to bilirubin-induced injury
Cerebellar injury phenotypes and BIND
Cerebellar projections

Transverse section of cerebellum and brainstem

Transverse section of cerebellum and brain-stem from a 34 gestational-week premature kernicteric infant formalin-fixed for two weeks. Yellow staining is evident in the cerebellar dentate nuclei (upper arrow) and vestibular nuclei at the pontomedullary junction (lower arrowhead). Photo is courtesy of Mahmdouha Ahdab-Barmada and reprinted with permission from Taylor-Francis Group (Ahdab Barmada M. The neuropathology of kernicterus: definitions and debate. In: Maisel MJ, Watchko JF editors. Neonatal jaundice. Amsterdam: Harwood Academic Publishers; 2000. p. 75e88

Whether cerebellar injury is primal or an integral part of disturbed neural circuitry in bilirubin-induced CNS damage is unclear. Movement disorders, however, are increasingly recognized to arise from abnormalities of neuronal circuitry rather than localized, circumscribed lesions. The cerebellum has extensive bidirectional circuitry projections to an array of brainstem nuclei and the cerebral cortex that modulate and refine motor activities. In this regard, the cerebellum is characteristically subdivided into three lobes based on neuroanatomic and phylogenetic criteria as well as by their primary afferent and efferent connections. They include:
(i) flocculonodular lobe (archicerebellum);
(ii) anterior lobe (paleocerebellum); and
(iii) posterior lobe (neocerebellum).

The archicerebellum, the oldest division phylogenically, receives extensive input from the vestibular system and is therefore also known as the vestibulocerebellum and is important for equilibrium control. The paleocerebellum, also a primitive region, receives extensive somatosensory input from the spinal cord, including the anterior and posterior spinocerebellar pathways that convey unconscious proprioception, and is therefore also known as the spinocerebellum. The neocerebellum is the most recently evolved region, receives most of the input from the cerebral cortex, and is thus termed the cerebrocerebellum. This area has greatly expanded in association with the extensive development of the cerebral cortex in mammals and especially primates. To cause serious longstanding dysfunction, cerebellar injury must typically involve the deep cerebellar nuclei and their projections.

Schematic of the bidirectional connectivity between the cerebellum and other

Schematic of the bidirectional connectivity between the cerebellum and other brain regions including the cerebral cortex. Most cerebro-cerebellar afferent projections pass through the basal (anterior or ventral) pontine nuclei and intermediate cerebellar peduncle, whereas most cerebello-cerebral efferent projections pass through the dentate and ventrolateral thalamic nuclei. DCN, deep cerebellar nuclei; RN, red nucleus; ATN, anterior thalamic nucleus; PFC, prefrontal cortex; MC, motor cortex; PC, parietal cortex; TC, temporal cortex; STN, subthalamic nucleus; APN, anterior pontine nuclei. Reprinted under the terms of the Creative Commons Attribution License from D’Angelo E, Casali S. Seeking a unified framework for cerebellar function and dysfunction: from circuit to cognition. Front Neural Circuits 2013; 6:116.

Given the vulnerability of the cerebellum to bilirubin-induced injury, cerebellar involvement should also be evident in classic kernicterus, contributing to neuromotor deficits observed therein. It is of interest, therefore, that cerebellar damage may play a role in the genesis of bilirubin-induced dystonia, a prominent neuromotor feature of chronic bilirubin encephalopathy in preterm and term neonates alike. This complex movement disorder is characterized by involuntary sustained muscle contractions that result in abnormal position and posture. Moreover, dystonia that is brief in duration results in chorea, and, if brief and repetitive, leads to athetosis ‒ conditions also classically observed in kernicterus. Recent evidence suggests that dystonic movements may depend on disruption of both basal ganglia and cerebellar neuronal networks, rather than isolated dysfunction of only one motor system.

Dystonia is also a prominent feature in Gunn rat pups and neonatal Ugt1‒/‒-deficient mice both robust models of kernicterus. The former is used as an experimental model of dystonia. Although these models show basal ganglia injury, the sine qua non of bilirubin-induced murine neuropathology is cerebellar damage and resultant cerebellar hypoplasia.

Studies are needed to define more precisely the motor network abnormalities in kernicterus and BIND. Magnetic resonance imaging (MRI) has been widely used in evaluating infants at risk for bilirubin-induced brain injury using conventional structural T1-and T2-weighted imaging. Infants with chronic bilirubin encephalopathy often demonstrate abnormal bilateral, symmetric, high-signal intensity on T2-weighted MRI of the globus pallidus and subthalamic nucleus, consistent with the neuropathology of kernicterus. Early postnatal MRI of at-risk infants, although frequently showing increased T1-signal in these regions, may give false-positive findings due to the presence of myelin in these structures.

Diffusion tensor imaging and tractography could be used to delineate long-term changes involving specific white matter pathways, further elucidating the neural basis of long-term disability in infants and children with chronic bilirubin encephalopathy and BIND. It will be equally valuable to use blood oxygen level-dependent (BOLD) “resting state” functional MRI to study intrinsic connectivity in order to identify vulnerable brain networks in neonates with kernicterus and BIND. Structural networks of the CNS (connectome) and functional network topology can be characterized in infants with kernicterus and BIND to determine disease-related pattern(s) with respect to both long- and short-range connectivity. These findings have the potential to shed novel insights into the pathogenesis of these disorders and their impact on complex anatomical connections and resultant functional deficits.

Audiologic impairment associated with bilirubin-induced neurologic damage

Cristen Olds, John S. Oghalai
Seminars in Fetal & Neonatal Medicine 20 (2015) 42e46
http://dx.doi.org/10.1016/j.siny.2014.12.006

Hyperbilirubinemia affects up to 84% of term and late preterm infants in the first week of life. The elevation of total serum/plasma bilirubin (TB) levels is generally mild, transitory, and, for most children, inconsequential. However, a subset of infants experiences lifelong neurological sequelae. Although the prevalence of classic kernicterus has fallen steadily in the USA in recent years, the incidence of jaundice in term and premature infants has increased, and kernicterus remains a significant problem in the global arena. Bilirubin-induced neurologic dysfunction (BIND) is a spectrum of neurological injury due to acute or sustained exposure of the central nervous system(CNS) to bilirubin. The BIND spectrum includes kernicterus, acute bilirubin encephalopathy, and isolated neural pathway dysfunction.

Animal studies have shown that unconjugated bilirubin passively diffuses across cell membranes and the blood‒brain barrier (BBB), and bilirubin not removed by organic anion efflux pumps accumulates within the cytoplasm and becomes toxic. Exposure of neurons to bilirubin results in increased oxidative stress and decreased neuronal proliferation and presynaptic neuro-degeneration at central glutaminergic synapses. Furthermore, bilirubin administration results in smaller spiral ganglion cell bodies, with decreased cellular density and selective loss of large cranial nerve VIII myelinated fibers. When exposed to bilirubin, neuronal supporting cells have been found to secrete inflammatory markers, which contribute to increased BBB permeability and bilirubin loading.

The jaundiced Gunn rat is the classic animal model of bilirubin toxicity. It is homozygous for a premature stop codon within the gene for UDP-glucuronosyltransferase family 1 (UGT1). The resultant gene product has reduced bilirubin-conjugating activity, leading to a state of hyperbilirubinemia. Studies with this rat model have led to the concept that impaired calcium homeostasis is an important mechanism of neuronal toxicity, with reduced expression of calcium-binding proteins in affected cells being a sensitive index of bilirubin-induced neurotoxicity. Similarly, application of bilirubin to cultured auditory neurons from brainstem cochlear nuclei results in hyperexcitability and excitotoxicity.

The auditory pathway and normal auditory brainstem response (ABR).

The auditory pathway and normal auditory brain-stem response (ABR). The ipsilateral (green) and contralateral (blue) auditory pathways are shown, with structures that are known to be affected by hyperbilirubinemia highlighted in red. Roman numerals in parentheses indicate corresponding waves in the normal human ABR (inset). Illustration adapted from the “Ear Anatomy” series by Robert Jackler and Christine Gralapp, with permission.

Bilirubin-induced neurologic dysfunction (BIND)

Vinod K. Bhutani, Ronald Wong
Seminars in Fetal & Neonatal Medicine 20 (2015) 1
http://dx.doi.org/10.1016/j.siny.2014.12.010

Beyond the traditional recognized areas of fulminant injury to the globus pallidus as seen in infants with kernicterus, other vulnerable areas include the cerebellum, hippocampus, and subthalamic nuclear bodies as well as certain cranial nerves. The hippocampus is a brain region that is particularly affected by age related morphological changes. It is generally assumed that a loss in hippocampal volume results in functional deficits that contribute to age-related cognitive deficits. Lower grey matter volumes within the limbic-striato-thalamic circuitry are common to other etiological mechanisms of subtle neurologic injury. Lower grey matter volumes in the amygdala, caudate, frontal and medial gyrus are found in schizophrenia and in the putamen in autism. Thus, in terms of brain volumetrics, schizophrenia and autism spectrum disorders have a clear degree of overlap that may reflect shared etiological mechanisms. Overlap with injuries observed in infants with BIND raises the question about how these lesions are arrived at in the context of the impact of common etiologies.

Stress-induced perinatal and transgenerational epigenetic programming of brain development and mental health

Olena Babenko, Igor Kovalchuk, Gerlinde A.S. Metz
Neuroscience and Biobehavioral Reviews 48 (2015) 70–91
http://dx.doi.org/10.1016/j.neubiorev.2014.11.013

Research efforts during the past decades have provided intriguing evidence suggesting that stressful experiences during pregnancy exert long-term consequences on the future mental wellbeing of both the mother and her baby. Recent human epidemiological and animal studies indicate that stressful experiences in utero or during early life may increase the risk of neurological and psychiatric disorders, arguably via altered epigenetic regulation. Epigenetic mechanisms, such as miRNA expression, DNA methylation, and histone modifications are prone to changes in response to stressful experiences and hostile environmental factors. Altered epigenetic regulation may potentially influence fetal endocrine programming and brain development across several generations. Only recently, however, more attention has been paid to possible transgenerational effects of stress. In this review we discuss the evidence of transgenerational epigenetic inheritance of stress exposure in human studies and animal models. We highlight the complex interplay between prenatal stress exposure, associated changes in miRNA expression and DNA methylation in placenta and brain and possible links to greater risks of schizophrenia, attention deficit hyperactivity disorder, autism, anxiety- or depression-related disorders later in life. Based on existing evidence, we propose that prenatal stress, through the generation of epigenetic alterations, becomes one of the most powerful influences on mental health in later life. The consideration of ancestral and prenatal stress effects on lifetime health trajectories is critical for improving strategies that support healthy development and successful aging.

Sensitive time-windows for susceptibility in neurodevelopmental disorders

Rhiannon M. Meredith, Julia Dawitz and Ioannis Kramvis
Trends in Neurosciences, June 2012; 35(6): 335-344
http://dx.doi.org:/10.1016/j.tins.2012.03.005

Many neurodevelopmental disorders (NDDs) are characterized by age-dependent symptom onset and regression, particularly during early postnatal periods of life. The neurobiological mechanisms preceding and underlying these developmental cognitive and behavioral impairments are, however, not clearly understood. Recent evidence using animal models for monogenic NDDs demonstrates the existence of time-regulated windows of neuronal and synaptic impairments. We propose that these developmentally-dependent impairments can be unified into a key concept: namely, time-restricted windows for impaired synaptic phenotypes exist in NDDs, akin to critical periods during normal sensory development in the brain. Existence of sensitive time-windows has significant implications for our understanding of early brain development underlying NDDs and may indicate vulnerable periods when the brain is more susceptible to current therapeutic treatments.

Fig (not shown)

Misregulated mechanisms underlying spine morphology in NDDs. Several proteins implicated in monogenic NDDs (highlighted in red) are linked to the regulation of the synaptic cytoskeleton via F-actin through different Rho-mediated signaling pathways (highlighted in green). Mutations in OPHN1, TSC1/2, FMRP, p21-activated kinase (PAK) are directly linked to human NDDs of intellectual disability. For instance, point mutations in OPHN1 and a PAK isoform are linked to non-syndromic mental retardation, whereas mutations or altered expression of TSC1/2 and FMRP are linked to TSC and FXS, respectively. Cytoplasmic interacting protein (CYFIP) and LIM-domain kinase 1 (LIMK1) are known to interact with FMRP and PAK, respectively [105]. LIMK1 is one of many dysregulated proteins contributing to the NDD Williams syndrome. Mouse models are available for all highlighted (red) proteins and reveal specific synaptic and behavioral deficits. Local protein synthesis in synapses, dendrites and glia is also regulated by proteins such as TSC1/2 and the FMRP/CYFIP complex. Abbreviations: 4EBP, 4E binding protein; eIF4E, eukaryotic translation initiation factor 4E.

Fig (not shown)

Sensitive time-windows, synaptic phenotypes and NDD gene targets. Sensitive time-windows exist in neural circuits, during which gene targets implicated in NDDs are normally expressed. Misregulation of these genes can affect multiple synaptic phenotypes during a restricted developmental period. The effect upon synaptic phenotypes is dependent upon the temporal expression of these NDD genes and their targets. (a) Expression outside a critical period of development will have no effect upon synaptic phenotypes. (b,c) A temporal expression pattern that overlaps with the onset (b) or closure (c) of a known critical period can alter the synaptic phenotype during that developmental time-window.

Outstanding questions

(1) Can treatment at early presymptomatic stages in animal models for NDDs prevent or ease the later synaptic, neuronal, and behavioral impairments?

(2) Are all sensory critical periods equally misregulated in mouse models for a specific NDD? Are there different susceptibilities for auditory, visual and somatosensory neurocircuits that reflect the degree of impairments observed in patients?

(3) If one critical period is missed or delayed during formation of a layer-specific connection in a network, does the network overcome this misregulated connectivity or plasticity window?

(4) In monogenic NDDs, does the severity of misregulating one particular time-window for synaptic establishment during development correlate with the importance of that gene for that synaptic circuit?

(5) Why do critical periods close in brain development?

(6) What underlies the regression of some altered synaptic phenotypes in Fmr1-KO mice?

(7) Can the concept of susceptible time-windows be applied to other NDDs, including schizophrenia and Tourette’s syndrome?

Cardiovascular

Cardiac output monitoring in newborns

Willem-Pieter de Boode
Early Human Development 86 (2010) 143–148
http://dx.doi.org:/10.1016/j.earlhumdev.2010.01.032

There is an increased interest in methods of objective cardiac output measurement in critically ill patients. Several techniques are available for measurement of cardiac output in children, although this remains very complex in newborns. Cardiac output monitoring could provide essential information to guide hemodynamic management. An overview is given of various methods of cardiac output monitoring with advantages and major limitations of each technology together with a short explanation of the basic principles.

Fick principle

According to the Fick principle the volume of blood flow in a given period equals the amount of substance entering the blood stream in the same period divided by the difference in concentrations of the substrate upstream respectively downstream to the point of entry in the circulation. This substance can be oxygen (O2-Fick) or carbon dioxide (CO2-FICK), so cardiac output can be calculated by dividing measured pulmonary oxygen uptake by the arteriovenous oxygen concentration difference. The direct O2-Fick method is regarded as gold standard in cardiac output monitoring in a research setting, despite its limitations. When the Fick principle is applied for carbon dioxide (CO2 Fick), the pulmonary carbon dioxide exchange is divided by the venoarterial CO2 concentration difference to calculate cardiac output.

In the modified CO2 Fick method pulmonary CO2 exchange is measured at the endotracheal tube. Measurement of total CO2 concentration in blood is more complex and simultaneous sampling of arterial and central venous blood is required. However, frequent blood sampling will result in an unacceptable blood loss in the neonatal population.

Blood flow can be calculated if the change in concentration of a known quantity of injected indicator is measured in time distal to the point of injection, so an indicator dilution curve can be obtained. Cardiac output can then be calculated with the use of the Stewart–Hamilton equation. Several indicators are used, such as indocyanine green, Evans blue and brilliant red in dye dilution, cold solutions in thermodilution, lithium in lithium dilution, and isotonic saline in ultrasound dilution.

Cardiovascular adaptation to extra uterine life

Alice Lawford, Robert MR Tulloh
Paediatrics And Child Health 2014; 25(1): 1-6.

The adaptation to extra uterine life is of interest because of its complexity and the ability to cause significant health concerns. In this article we describe the normal changes that occur and the commoner abnormalities that are due to failure of normal development and the effect of congenital cardiac disease. Abnormal development may occur as a result of problems with the mother, or with the fetus before birth. After birth it is essential to determine whether there is an underlying abnormality of the fetal pulmonary or cardiac development and to determine the best course of management of pulmonary hypertension or congenital cardiac disease. Causes of underdevelopment, maldevelopment and maladaptation are described as are the causes of critical congenital heart disease. The methods of diagnosis and management are described to allow the neonatologist to successfully manage such newborns.

Fetal vascular structures that exist to direct blood flow

Fetal structure	Function
Arterial duct	Connects pulmonary artery to the aorta and shunts blood right to left; diverting flow away from fetal lungs
Foramen ovale	Opening between the two atria thatdirects blood flow returning to right atrium through the septal wall into the left atrium bypassing lungs
Ductus venosus	Receives oxygenated blood fromumbilical vein and directs it to the inferior vena cava and right atrium
Umbilical arteries	Carrying deoxygenated blood fromthe fetus to the placenta
Umbilical vein	Carrying oxygenated blood from theplacenta to the fetus

Maternal causes of congenital heart disease

Maternal disorders	rubella, SLE, diabetes mellitus
Maternal drug use	Warfarin, alcohol
Chromosomal abnormality	Down, Edward, Patau, Turner, William, Noonan

Fetal and Neonatal Circulation The fetal circulation is specifically adapted to efficiently exchange gases, nutrients, and wastes through placental circulation. Upon birth, the shunts (foramen ovale, ductus arteriosus, and ductus venosus) close and the placental circulation is disrupted, producing the series circulation of blood through the lungs, left atrium, left ventricle, systemic circulation, right heart, and back to the lungs.

Clinical monitoring of systemic hemodynamics in critically ill newborns

Willem-Pieter de Boode
Early Human Development 86 (2010) 137–141
http://dx.doi.org:/10.1016/j.earlhumdev.2010.01.031

Circulatory failure is a major cause of mortality and morbidity in critically ill newborn infants. Since objective measurement of systemic blood flow remains very challenging, neonatal hemodynamics is usually assessed by the interpretation of various clinical and biochemical parameters. An overview is given about the predictive value of the most used indicators of circulatory failure, which are blood pressure, heart rate, urine output, capillary refill time, serum lactate concentration, central–peripheral temperature difference, pH, standard base excess, central venous oxygen saturation and color.

Key guidelines

➢ The clinical assessment of cardiac output by the interpretation of indirect parameters of systemic blood flow is inaccurate, irrespective of the level of experience of the clinician

➢ Using blood pressure to diagnose low systemic blood flow will consequently mean that too many patients will potentially be undertreated or overtreated, both with substantial risk of adverse effects and iatrogenic damage.

➢ Combining different clinical hemodynamic parameters enhances the predictive value in the detection of circulatory failure, although accuracy is still limited.

➢ Variation in time (trend monitoring) might possibly be more informative than individual, static values of clinical and biochemical parameters to evaluate the adequacy of neonatal circulation.

Monitoring oxygen saturation and heart rate in the early neonatal period

J.A. Dawson, C.J. Morley
Seminars in Fetal & Neonatal Medicine 15 (2010) 203e207
http://dx.doi.org:/10.1016/j.siny.2010.03.004

Pulse oximetry is commonly used to assist clinicians in assessment and management of newly born infants in the delivery room (DR). In many DRs, pulse oximetry is now the standard of care for managing high risk infants, enabling immediate and dynamic assessment of oxygenation and heart rate. However, there is little evidence that using pulse oximetry in the DR improves short and long term outcomes. We review the current literature on using pulse oximetry to measure oxygen saturation and heart rate and how to apply current evidence to management in the DR.

Practice points

Understand how SpO2 changes in the first minutes after birth.
Apply a sensor to an infant’s right wrist as soon as possible after birth.
Attach sensor to infant then to oximeter cable.
Use two second averaging and maximum sensitivity.

Using pulse oximetry assists clinicians:

Assess changes in HR in real time during transition.
Assess oxygenation and titrate the administration of oxygen to maintain oxygenation within the appropriate range for SpO2 during the first minutes after birth.

Research directions

What are the appropriate centiles to target during the minutes after birth to prevent hypoxia and hyperoxia: 25th to 75th, or 10th to 90th, or just the 50th (median)?
Can the inspired oxygen be titrated against the SpO2 to keep the SpO2 in the ‘normal range’?
Does the use of centile charts in the DR for HR and oxygen saturation reduce the rate of hyperoxia when infants are treated with oxygen.
Does the use of pulse oximetry immediately after birth improve short term outcomes, e.g. efficacy of immediate respiratory support, intubation rates in the DR, percentage of inspired oxygen, rate of use of adrenalin or chest compressions, duration of hypoxia/hyperoxia and bradycardia.
Does the use of pulse oximetry in the DR improve short term respiratory and long term neurodevelopmental outcomes for preterm infants, e.g. rate of intubation, use of surfactant, and duration of ventilation, continuous positive airway pressure, or supplemental oxygen?
Can all modern pulse oximeters be used effectively in the DR or do some have a longer delay before giving an accurate signal and more movement artefact?
Would a longer averaging time result in more stable data?

Peripheral haemodynamics in newborns: Best practice guidelines

Michael Weindling, Fauzia Paize
Early Human Development 86 (2010) 159–165
http://dx.doi.org:/10.1016/j.earlhumdev.2010.01.033

Peripheral hemodynamics refers to blood flow, which determines oxygen and nutrient delivery to the tissues. Peripheral blood flow is affected by vascular resistance and blood pressure, which in turn varies with cardiac function. Arterial oxygen content depends on the blood hemoglobin concentration (Hb) and arterial pO2; tissue oxygen delivery depends on the position of the oxygen-dissociation curve, which is determined by temperature and the amount of adult or fetal hemoglobin. Methods available to study tissue perfusion include near-infrared spectroscopy, Doppler flowmetry, orthogonal polarization spectral imaging and the peripheral perfusion index. Cardiac function, blood gases, Hb, and peripheral temperature all affect blood flow and oxygen extraction. Blood pressure appears to be less important. Other factors likely to play a role are the administration of vasoactive medications and ventilation strategies, which affect blood gases and cardiac output by changing the intrathoracic pressure.

graphic

NIRS with partial venous occlusion to measure venous oxygen saturation

NIRS with partial venous occlusion to measure venous oxygen saturation. Taken from Yoxall and Weindling

Schematic representation of the biphasic relationship between oxygen delivery and oxygen consumption in tissue

graphic

Schematic representation of the biphasic relationship between oxygen delivery and oxygen consumption in tissue. (a) oxygen delivery (DO2). (b) As DO2 decreases, VO2 is dependent on DO2. The slope of the line indicates the FOE, which in this case is about 0.50. (c) The slope of the line indicates the FOE in the normal situation where oxygenation is DO2 independent, usually < 0.35

The oxygen-dissociation curve

graphic

The oxygen-dissociation curve

Considerable information about the response of the peripheral circulation has been obtained using NIRS with venous occlusion. Although these measurements were validated against blood co-oximetry in human adults and infants, they can only be made intermittently by a trained operator and are thus not appropriate for general clinical use. Further research is needed to find other better measures of peripheral perfusion and oxygenation which may be easily and continuously monitored, and which could be useful in a clinical setting.

Peripheral oxygenation and management in the perinatal period

Michael Weindling
Seminars in Fetal & Neonatal Medicine 15 (2010) 208e215
http://dx.doi.org:/10.1016/j.siny.2010.03.005

The mechanisms for the adequate provision of oxygen to the peripheral tissues are complex. They involve control of the microcirculation and peripheral blood flow, the position of the oxygen dissociation curve including the proportion of fetal and adult hemoglobin, blood gases and viscosity. Systemic blood pressure appears to have little effect, at least in the non-shocked state. The adequate delivery of oxygen (DO2) depends on consumption (VO2), which is variable. The balance between VO2 and DO2 is given by fractional oxygen extraction (FOE ¼ VO2/DO2). FOE varies from organ to organ and with levels of activity. Measurements of FOE for the whole body produce a range of about 0.15-0.33, i.e. the body consumes 15-33% of oxygen transported.

Fig (not shown)

Biphasic relationship between oxygen delivery (DO2) and oxygen consumption (VO2) in tissue. Dotted lines show fractional oxygen extraction (FOE). ‘A’ indicates the normal situation when VO2 is independent ofDO2 and FOE is about 0.30. AsDO2 decreases in the direction of the arrow, VO2 remains independent of DO2 until the critical point is reached at ‘B’; in this illustration, FOE is about 0.50. The slope of the dotted line indicates the FOE (¼ VO2/DO2), which increases progressively as DO2 decreases.

$Relationship between haemoglobin F fraction (HbF) and peripheral fractional oxygen extraction$

Relationship between haemoglobin F fraction (HbF) and peripheral fractional oxygen extraction

Graphic
(A)Relationship between haemoglobin F fraction (HbF) and peripheral fractional oxygen extraction in anaemic and control infants. (From Wardle et al.) (B) HbF synthesis and concentration. (From Bard and Widness.) (C) Oxygen dissociation curve.

$Peripheral fractional oxygen extraction in babies$

Peripheral fractional oxygen extraction in babies

graphic

Peripheral fractional oxygen extraction in babies with asymptomatic or symptomatic anemia compared to controls. Bars represent the median for each group. (From Wardle et al.)

Practice points

Peripheral tissue DO2 is complex: cardiac function, blood gases, Hb concentration and the proportion of HbF, and peripheral temperature all play a part in determining blood flow and oxygen extraction in the sick, preterm infant. Blood pressure appears to be less important.
Other factors likely to play a role are the administration of vasoactive medications and ventilation strategies, which affect blood gases and cardiac output by changing intrathoracic pressure.
Central blood pressure is a poor surrogate measurement for the adequacy of DO2 to the periphery. Direct measurement, using NIRS, laser Doppler flowmetry or other means, may give more useful information.
Reasons for total hemoglobin concentration (Hb) being a relatively poor indicator of the adequacy of the provision of oxygen to the tissues:

Hb is only indirectly related to red blood cell volume, which may be a better indicator of the body’s oxygen delivering capacity.
Hb-dependent oxygen availability depends on the position of the oxygen-hemoglobin dissociation curve.
An individual’s oxygen requirements vary with time and from organ to organ. This means that DO2 also needs to vary.
It is possible to compensate for a low Hb by increasing cardiac output and ventilation, and so the ability to compensate for anemia depends on an individual’s cardio-respiratory reserve as well as Hb.
The normal decrease of Hb during the first few weeks of life in both full-term and preterm babies usually occurs without symptoms or signs of anemia or clinical consequences.

The relationship between VO2 and DO2 is complex and various factors need to be taken into account, including the position of the oxygen dissociation curve, determined by the proportion of HbA and HbF, temperature and pH. Furthermore, diffusion of oxygen from capillaries to the cell depends on the oxygen tension gradient between erythrocytes and the mitochondria, which depends on microcirculatory conditions, e.g. capillary PO2, distance of the cell from the capillary (characterized by intercapillary distances) and the surface area of open capillaries. The latter can change rapidly, for example, in septic shock where arteriovenous shunting occurs associated with tissue hypoxia in spite of high DO2 and a low FOE.

Changes in local temperature deserve particular consideration. When the blood pressure is low, there may be peripheral vasoconstriction with decreased local perfusion and DO2. However, the fall in local tissue temperature would also be expected to be associated with a decreased metabolic rate and a consequent decrease in VO2. Thus a decreased DO2 may still be appropriate for tissue needs.

Pulmonary

Accurate Measurements of Oxygen Saturation in Neonates: Paired Arterial and Venous Blood Analyses

Shyang-Yun Pamela K. Shiao
Newborn and Infant Nurs Rev, 2005; 5(4): 170–178
http://dx.doi.org:/10.1053/j.nainr.2005.09.001

Oxygen saturation (So2) measurements (functional measurement, So2; and fractional measurement, oxyhemoglobin [Hbo2]) and monitoring are commonly investigated as a method of assessing oxygenation in neonates. Differences exist between the So2 and Hbo2 when blood tests are performed, and clinical monitors indicate So2 values. Oxyhemoglobin will decrease with the increased levels of carbon monoxide hemoglobin (Hbco) and methemo-globin (MetHb), and it is the most accurate measurements of oxygen (O2) association of hemoglobin (Hb). Pulse oximeter (for pulse oximetry saturation [Spo2] measurement) is commonly used in neonates. However, it will not detect the changes of Hb variations in the blood for accurate So2 measurements. Thus, the measurements from clinical oximeters should be used with caution. In neonates, fetal hemoglobin (HbF) accounts for most of the circulating Hb in their blood. Fetal hemoglobin has a high O2 affinity, thus releases less O2 to the body tissues, presenting a left-shifted Hbo2 dissociation curve.5,6 To date, however, limited data are available with HbF correction, for accurate arterial and venous (AV) So2 measurements (arterial oxygen saturation [Sao2] and venous oxygen saturation [Svo2]) in neonates, using paired AV blood samples.

In a study of critically ill adult patients, increased pulmonary CO production and elevation in arterial Hbco but not venous Hbco were documented by inflammatory stimuli inducing pulmonary heme oxygenase–1. In normal adults, venous Hbco level might be slightly higher than or equal to arterial Hbco because of production of CO by enzyme heme oxygenase–2, which is predominantly produced in the liver and spleen. However, hypoxia or pulmonary inflammation could induce heme oxygenase–1 to increase endogenous CO, thus elevating pulmonary arterial and systemic arterial Hbco levels in adults. Both endogenous and exogenous CO can suppress proliferation of pulmonary smooth muscles, a significant consideration for the prevention of chronic lung diseases in newborns. Despite these considerations, a later study in healthy adults indicated that the AV differences in Hbco were from technical artifacts and perhaps from inadequate control of different instruments. Thus, further studies are needed to provide more definitive answers for the AV differences of Hbco for adults and neonates with acute and chronic lung diseases.

Methemoglobin is an indicator of Hb oxidation and is essential for accurate measurement of Hbo2, So2, and oxygenation status. No evidence exists to show the AV MetHb difference, although this difference was elucidated with the potential changes of MetHb with different O2 levels. Methemoglobin can be increased with nitric oxide (NO) therapy, used in respiratory distress syndrome (RDS) to reduce pulmonary hypertension and during heart surgery. Nitric oxide, in vitro, is an oxidant of Hb, with increased O2 during ischemia reperfusion. In hypoxemic conditions in vivo, nitrohemoglobin is a product generated by vessel responsiveness to nitrovasodilators. Nitro-hemoglobin can be spontaneously reversible in vivo, requiring no chemical agents or reductase. However, when O2 levels were increased experimentally in vitro following acidic conditions (pH 6.5) to simulate reperfusion conditions, MetHb levels were increased for the hemolysates (broken red cells). Nitrite-induced oxidation of Hb was associated with an increase in red blood cell membrane rigidity, thus contributing to Hb breakdown. A newer in vitro study of whole blood cells, however, concluded that MetHb formation is not dependent on increased O2 levels. Additional studies are needed to examine in vivo reperfusion of O2 and MetHb effects.

Purpose: The aim of this study was to examine the accuracy of arterial oxygen saturation (Sao2) and venous oxygen saturation (Svo2) with paired arterial and venous (AV) blood in relation to pulse oximetry saturation (Spo2) and oxyhemoglobin (Hbo2) with fetal hemoglobin determination, and their Hbo2 dissociation curves. Method: Twelve preterm neonates with gestational ages ranging from 27 to 34 weeks at birth, who had umbilical AV lines inserted, were investigated. Analyses were performed with 37 pairs of AV blood samples by using a blood volume safety protocol. Results: The mean differences between Sao2 and Svo2, and AV Hbo2 were both 6 percent (F6.9 and F6.7 percent, respectively), with higher Svo2 than those reported for adults. Biases were 2.1 – 0.49 for Sao2, 2.0 – 0.44 for Svo2, and 3.1 – 0.45 for Spo2, compared against Hbo2. With left-shifted Hbo2 dissociation curves in neonates, for the critical values of oxygen tension values between 50 and 75 millimeters of mercury, Hbo2 ranged from 92 to 93.4 percent; Sao2 ranged from 94.5 to 95.7 percent; and Spo2 ranged from 93.7 to 96.3 percent (compared to 85–94 percent in healthy adults). Conclusions: In neonates, both left-shifted Hbo2 dissociation curve and lower AV differences of oxygen saturation measurements indicated low flow of oxygen to the body tissues. These findings demonstrate the importance of accurate assessment of oxygenation statues in neonates.

In these neonates, the mean AV blood differences for both So2 and Hbo2 were about 6 percent, which was much lower than those reported for healthy adults (23 percent) for O2 supply and demand. In addition, with very high levels of HbF releasing less O2 to the body tissue, the results of blood analyses are worrisome for these critically ill neonates for low systemic oxygen states. O’Connor and Hall determined AV So2 in neonates without HbF determination. Much of the AV So2 difference is dependent on Svo2 measurement. The ranges of Svo2 spanned for 35 percent, and the ranges of Sao2 spanned 6 percent in these neonates. The greater intervals for Svo2 measurements contribute to greater sensitivity for the measurements (than Sao2 measurements) in responding to nursing care and changes of O2 demand. Thus, Svo2 measurement is essential for better assessment of oxygenation status in neonates.

The findings of this study on AV differences of So2 were limited with very small number of paired AV blood samples. However, critically ill neonates need accurate assessment of oxygenation status because of HbF, which releases less O2 to the tissues. Decreased differences of AV So2 measurements added further possibilities of lower flow of O2 to the body tissues and demonstrated the greater need to accurately assess the proper oxygenation in the neonates. The findings of this study continued to clarify the accuracy of So2 measurements for neonates. Additional studies are needed to examine So2 levels in neonates to further validate these findings by using larger sample sizes.

Neonatal ventilation strategies and long-term respiratory outcomes

Sandeep Shetty, Anne Greenough
Early Human Development 90 (2014) 735–739
http://dx.doi.org/10.1016/j.earlhumdev.2014.08.020

Long-term respiratory morbidity is common, particularly in those born very prematurely and who have developed bronchopulmonary dysplasia (BPD), but it does occur in those without BPD and in infants born at term. A variety of neonatal strategies have been developed, all with short-term advantages, but meta-analyses of randomized controlled trials (RCTs) have demonstrated that only volume-targeted ventilation and prophylactic high-frequency oscillatory ventilation (HFOV) may reduce BPD. Few RCTs have incorporated long-term follow-up, but one has demonstrated that prophylactic HFOV improves respiratory and functional outcomes at school age, despite not reducing BPD. Results from other neonatal interventions have demonstrated that any impact on BPD may not translate into changes in long-term outcomes. All future neonatal ventilation RCTs should have long-term outcomes rather than BPD as their primary outcome if they are to impact on clinical practice.

A Model Analysis of Arterial Oxygen Desaturation during Apnea in Preterm Infants

Scott A. Sands, BA Edwards, VJ Kelly, MR Davidson, MH Wilkinson, PJ Berger
PLoS Comput Biol 5(12): e1000588
http://dx.doi.org:/10.1371/journal.pcbi.1000588

Rapid arterial O2 desaturation during apnea in the preterm infant has obvious clinical implications but to date no adequate explanation for why it exists. Understanding the factors influencing the rate of arterial O2 desaturation during apnea (_SSaO2 ) is complicated by the non-linear O2 dissociation curve, falling pulmonary O2 uptake, and by the fact that O2 desaturation is biphasic, exhibiting a rapid phase (stage 1) followed by a slower phase when severe desaturation develops (stage 2). Using a mathematical model incorporating pulmonary uptake dynamics, we found that elevated metabolic O2 consumption accelerates _SSaO2 throughout the entire desaturation process. By contrast, the remaining factors have a restricted temporal influence: low pre-apneic alveolar PO2 causes an early onset of desaturation, but thereafter has little impact; reduced lung volume, hemoglobin content or cardiac output, accelerates _SSaO2 during stage 1, and finally, total blood O2 capacity (blood volume and hemoglobin content) alone determines _SSaO2 during stage 2. Preterm infants with elevated metabolic rate, respiratory depression, low lung volume, impaired cardiac reserve, anemia, or hypovolemia, are at risk for rapid and profound apneic hypoxemia. Our insights provide a basic physiological framework that may guide clinical interpretation and design of interventions for preventing sudden apneic hypoxemia.

A novel approach to study oxidative stress in neonatal respiratory distress syndrome

Reena Negi, D Pande, K Karki, A Kumar, RS Khanna, HD Khanna
BBA Clinical 3 (2015) 65–69
http://dx.doi.org/10.1016/j.bbacli.2014.12.001

Oxidative stress is an imbalance between the systemic manifestation of reactive oxygen species and a biological system’s ability to readily detoxify the reactive intermediates or to repair the resulting damage. It is a physiological event in the fetal-to-neonatal transition, which is actually a great stress to the fetus. These physiological changes and processes greatly increase the production of free radicals, which must be controlled by the antioxidant defense system, the maturation of which follows the course of the gestation. This could lead to several functional alterations with important repercussions for the infants. Adequately mature and healthy infants are able to tolerate this drastic change in the oxygen concentration. A problem occurs when the intrauterine development is incomplete or abnormal. Preterm or intrauterine growth retarded (IUGR) and low birth weight neonates are typically of this kind. An oxidant/antioxidant imbalance in infants is implicated in the pathogenesis of the major complications of prematurity including respiratory distress syndrome (RDS), necrotizing enterocolitis (NEC), chronic lung disease, retinopathy of prematurity and intraventricular hemorrhage (IVH).

Background: Respiratory distress syndrome of the neonate (neonatal RDS) is still an important problem in treatment of preterm infants. It is accompanied by inflammatory processes with free radical generation and oxidative stress. The aim of study was to determine the role of oxidative stress in the development of neonatal RDS. Methods: Markers of oxidative stress and antioxidant activity in umbilical cord blood were studied in infants with neonatal respiratory distress syndrome with reference to healthy newborns. Results: Status of markers of oxidative stress (malondialdehyde, protein carbonyl and 8-hydroxy-2-deoxy guanosine) showed a significant increase with depleted levels of total antioxidant capacity in neonatal RDS when compared to healthy newborns. Conclusion: The study provides convincing evidence of oxidative damage and diminished antioxidant defenses in newborns with RDS. Neonatal RDS is characterized by damage of lipid, protein and DNA, which indicates the augmentation of oxidative stress. General significance: The identification of the potential biomarker of oxidative stress consists of a promising strategy to study the pathophysiology of neonatal RDS.

Neonatal respiratory distress syndrome represents the major lung complications of newborn babies. Preterm neonates suffer from respiratory distress syndrome (RDS) due to immature lungs and require assisted ventilation with high concentrations of oxygen. The pathogenesis of this disorder is based on the rapid formation of the oxygen reactive species, which surpasses the detoxification capacity of antioxidative defense system. The high chemical reactivity of free radical leads to damage to a variety of cellular macro molecules including proteins, lipids and nucleic acid. This results in cell injury and may induce respiratory cell death.

Malondialdehyde (MDA) is one of the final products of polyunsaturated fatty acids peroxidation. The present study showed increased concentration of MDA in neonates with respiratory disorders than that of control in consonance with the reported study.

Anemia, Apnea of Prematurity, and Blood Transfusions

Kelley Zagol, Douglas E. Lake, Brooke Vergales, Marion E. Moorman, et al
J Pediatr 2012;161:417-21
http://dx.doi.org:/10.1016/j.jpeds.2012.02.044

The etiology of apnea of prematurity is multifactorial; however, decreased oxygen carrying capacity may play a role. The respiratory neuronal network in neonates is immature, particularly in those born preterm, as demonstrated by their paradoxical response to hypoxemia. Although adults increase the minute ventilation in response to hypoxemia, newborns have a brief increase in ventilation followed by periodic breathing, respiratory depression, and occasionally cessation of respiratory effort. This phenomenon may be exacerbated by anemia in preterm newborns, where a decreased oxygen carrying capacity may result in decreased oxygen delivery to the central nervous system, a decreased efferent output of the respiratory neuronal network, and an increase in apnea.

Objective Compare the frequency and severity of apneic events in very low birth weight (VLBW) infants before and after blood transfusions using continuous electronic waveform analysis. Study design We continuously collected waveform, heart rate, and oxygen saturation data from patients in all 45 neonatal intensive care unit beds at the University of Virginia for 120 weeks. Central apneas were detected using continuous computer processing of chest impedance, electrocardiographic, and oximetry signals. Apnea was defined as respiratory pauses of >10, >20, and >30 seconds when accompanied by bradycardia (<100 beats per minute) and hypoxemia (<80% oxyhemoglobin saturation as detected by pulse oximetry). Times of packed red blood cell transfusions were determined from bedside charts. Two cohorts were analyzed. In the transfusion cohort, waveforms were analyzed for 3 days before and after the transfusion for all VLBW infants who received a blood transfusion while also breathing spontaneously. Mean apnea rates for the previous 12 hours were quantified and differences for 12 hours before and after transfusion were compared. In the hematocrit cohort, 1453 hematocrit values from all VLBW infants admitted and breathing spontaneously during the time period were retrieved, and the association of hematocrit and apnea in the next 12 hours was tested using logistic regression. Results Sixty-seven infants had 110 blood transfusions during times when complete monitoring data were available. Transfusion was associated with fewer computer-detected apneic events (P < .01). Probability of future apnea occurring within 12 hours increased with decreasing hematocrit values (P < .001). Conclusions Blood transfusions are associated with decreased apnea in VLBW infants, and apneas are less frequent at higher hematocrits.

Bronchopulmonary dysplasia: The earliest and perhaps the longest lasting obstructive lung disease in humans

Silvia Carraro, M Filippone, L Da Dalt, V Ferraro, M Maretti, S Bressan, et al.
Early Human Development 89 (2013) S3–S5
http://dx.doi.org/10.1016/j.earlhumdev.2013.07.015

Bronchopulmonary dysplasia (BPD) is one of the most important sequelae of premature birth and the most common form of chronic lung disease of infancy, an umbrella term for a number of different diseases that evolve as a consequence of a neonatal respiratory disorder. BPD is defined as the need for supplemental oxygen for at least 28 days after birth, and its severity is graded according to the respiratory support required at 36 post-menstrual weeks.

BPD was initially described as a chronic respiratory disease occurring in premature infants exposed to mechanical ventilation and oxygen supplementation. This respiratory disease (later named “old BPD”) occurred in relatively large premature newborn and, from a pathological standpoint, it was characterized by intense airway inflammation, disruption of normal pulmonary structures and lung fibrosis.

Bronchopulmonary dysplasia (BPD) is one of the most important sequelae of premature birth and the most common form of chronic lung disease of infancy. From a clinical standpoint BPD subjects are characterized by recurrent respiratory symptoms, which are very frequent during the first years of life and, although becoming less severe as children grow up, they remain more common than in term-born controls throughout childhood, adolescence and into adulthood. From a functional point of view BPD subjects show a significant airflow limitation that persists during adolescence and adulthood and they may experience an earlier and steeper decline in lung function during adulthood. Interestingly, patients born prematurely but not developing BPD usually fare better, but they too have airflow limitations during childhood and later on, suggesting that also prematurity per se has life-long detrimental effects on pulmonary function. For the time being, little is known about the presence and nature of pathological mechanisms underlying the clinical and functional picture presented by BPD survivors. Nonetheless, recent data suggest the presence of persistent neutrophilic airway inflammation and oxidative stress and it has been suggested that BPD may be sustained in the long term by inflammatory pathogenic mechanisms similar to those underlying COPD. This hypothesis is intriguing but more pathological data are needed. A better understanding of these pathogenetic mechanisms, in fact, may be able to orient the development of novel targeted therapies or prevention strategies to improve the overall respiratory health of BPD patients.

We have a limited understanding of the presence and nature of pathological mechanisms in the lung of BPD survivors. The possible role of asthma-like inflammation has been investigated because BPD subjects often present with recurrent wheezing and other symptoms resembling asthma during their childhood and adolescence. But BPD subjects have normal or lower than normal exhaled nitric oxide levels and exhaled air temperatures, whereas they are higher than normal in asthmatic patients.

Of all obstructive lung diseases in humans, BPD has the earliest onset and is possibly the longest lasting. Given its frequent association with other conditions related to preterm birth (e.g. growth retardation, pulmonary hypertension, neurodevelopmental delay, hearing defects, and retinopathy of prematurity), it often warrants a multidisciplinary management.

Effects of Sustained Lung Inflation, a lung recruitment maneuver in primary acute respiratory distress syndrome, in respiratory and cerebral outcomes in preterm infants

Chiara Grasso, Pietro Sciacca, Valentina Giacchi, Caterina Carpinato, et al.
Early Human Development 91 (2015) 71–75
http://dx.doi.org/10.1016/j.earlhumdev.2014.12.002

Background: Sustained Lung Inflation (SLI) is a maneuver of lung recruitment in preterm newborns at birth that can facilitate the achieving of larger inflation volumes, leading to the clearance of lung fluid and formation of functional residual capacity (FRC). Aim: To investigate if Sustained Lung Inflation (SLI) reduces the need of invasive procedures and iatrogenic risks. Study design: 78 newborns (gestational age ≤ 34 weeks, weighing ≤ 2000 g) who didn’t breathe adequately at birth and needed to receive SLI in addition to other resuscitation maneuvers (2010 guidelines). Subjects: 78 preterm infants born one after the other in our department of Neonatology of Catania University from 2010 to 2012. Outcome measures: The need of intubation and surfactant, the ventilation required, radiological signs, the incidence of intraventricular hemorrhage (IVH), periventricular leukomalacia, retinopathy in prematurity from III to IV plus grades, bronchopulmonary dysplasia, patent ductus arteriosus, pneumothorax and necrotizing enterocolitis. Results: In the SLI group infants needed less intubation in the delivery room (6% vs 21%; p b 0.01), less invasive mechanical ventilation (14% vs 55%; p ≤ 0.001) and shorter duration of ventilation (9.1 days vs 13.8 days; p ≤ 0.001). There wasn’t any difference for nasal continuous positive airway pressure (82% vs 77%; p = 0.43); but there was less surfactant administration (54% vs 85%; p ≤ 0.001) and more infants received INSURE (40% vs 29%; p=0.17). We didn’t found any differences in the outcomes, except for more mild intraventricular hemorrhage in the SLI group (23% vs 14%; p = 0.15; OR= 1.83). Conclusion: SLI is easier to perform even with a single operator, it reduces the necessity of more complicated maneuvers and surfactant without statistically evident adverse effects.

Long-term respiratory consequences of premature birth at less than 32 weeks of gestation

Anne Greenough
Early Human Development 89 (2013) S25–S27
http://dx.doi.org/10.1016/j.earlhumdev.2013.07.004

Chronic respiratory morbidity is a common adverse outcome of very premature birth, particularly in infants who had developed bronchopulmonary dysplasia (BPD). Prematurely born infants who had BPD may require supplementary oxygen at home for many months and affected infants have increased healthcare utilization until school age. Chest radiograph abnormalities are common; computed tomography of the chest gives predictive information in children with ongoing respiratory problems. Readmission to hospital is common, particularly for those who have BPD and suffer respiratory syncytial virus lower respiratory infections (RSV LRTIs). Recurrent respiratory symptoms requiring treatment are common and are associated with evidence of airways obstruction and gas trapping. Pulmonary function improves with increasing age, but children with BPD may have ongoing airflow limitation. Lung function abnormalities may be more severe in those who had RSV LRTIs, although this may partly be explained by worse premorbid lung function. Worryingly, lung function may deteriorate during the first year. Longitudinal studies are required to determine if there is catch up growth.

Long-term pulmonary outcomes of patients with bronchopulmonary dysplasia

Anita Bhandari and Sharon McGrath-Morrow
Seminars in Perinatology 37 (2013)132–137
http://dx.doi.org/10.1053/j.semperi.2013.01.010

Bronchopulmonary dysplasia (BPD) is the commonest cause of chronic lung disease in infancy. The incidence of BPD has remained unchanged despite many advances in neonatal care. BPD starts in the neonatal period but its effects can persist long term. Premature infants with BPD have a greater incidence of hospitalization, and continue to have a greater respiratory morbidity and need for respiratory medications, compared to those without BPD. Lung function abnormalities, especially small airway abnormalities, often persist. Even in the absence of clinical symptoms, BPD survivors have persistent radiological abnormalities and presence of emphysema has been reported on chest computed tomography scans. Concern regarding their exercise tolerance remains. Long-term effects of BPD are still unknown, but given reports of a more rapid decline in lung function and their susceptibility to develop chronic obstructive pulmonary disease phenotype with aging, it is imperative that lung function of survivors of BPD be closely monitored.

Neonatal ventilation strategies and long-term respiratory outcomes

Sandeep Shetty, Anne Greenough
Early Human Development 90 (2014) 735–739
http://dx.doi.org/10.1016/j.earlhumdev.2014.08.020

Long-term respiratory morbidity is common, particularly in those born very prematurely and who have developed bronchopulmonary dysplasia (BPD), but it does occur in those without BPD and in infants born at term. A variety of neonatal strategies have been developed, all with short-term advantages, but meta-analyses of randomized controlled trials (RCTs) have demonstrated that only volume-targeted ventilation and prophylactic high-frequency oscillatory ventilation (HFOV) may reduce BPD. Few RCTs have incorporated long-term follow-up, but one has demonstrated that prophylactic HFOV improves respiratory and functional outcomes at school age, despite not reducing BPD. Results from other neonatal interventions have demonstrated that any impact on BPD may not translate into changes in long-term outcomes. All future neonatal ventilation RCTs should have long-term outcomes rather than BPD as their primary outcome if they are to impact on clinical practice.

Prediction of neonatal respiratory distress syndrome in term pregnancies by assessment of fetal lung volume and pulmonary artery resistance index

Mohamed Laban, GM Mansour, MSE Elsafty, AS Hassanin, SS EzzElarab
International Journal of Gynecology and Obstetrics 128 (2015) 246–250
http://dx.doi.org/10.1016/j.ijgo.2014.09.018

Objective: To develop reference cutoff values for mean fetal lung volume (FLV) and pulmonary artery resistance index (PA-RI) for prediction of neonatal respiratory distress syndrome (RDS) in low-risk term pregnancies. Methods: As part of a cross-sectional study, women aged 20–35 years were enrolled and admitted to a tertiary hospital in Cairo, Egypt, for elective repeat cesarean at 37–40 weeks of pregnancy between January 1, 2012, and July 31, 2013. FLV was calculated by virtual organ computer-aided analysis, and PA-RI was measured by Doppler ultrasonography before delivery. Results: A total of 80 women were enrolled. Neonatal RDS developed in 11 (13.8%) of the 80 newborns. Compared with neonates with RDS, healthy neonates had significantly higher FLVs (P b 0.001) and lower PA-RIs (P b 0.001). Neonatal RDS is less likely with FLV of at least 32 cm³ or PA-RI less than or equal to 0.74. Combining these two measures improved the accuracy of prediction. Conclusion: The use of either FLV or PA-RI predicted neonatal RDS. The predictive value increased when these two measures were combined

Pulmonary surfactant – a front line of lung host defense, 2003 JCI0318650.f2

Pulmonary hypertension in bronchopulmonary dysplasia

Sara K.Berkelhamer, Karen K.Mestan, and Robin H. Steinhorn
Seminars In Perinatology 37 (2013)124–131
http://dx.doi.org/10.1053/j.semperi.2013.01.009

Pulmonary hypertension (PH) is a common complication of neonatal respiratory diseases, including bronchopulmonary dysplasia (BPD), and recent studies have increased aware- ness that PH worsens the clinical course, morbidity and mortality of BPD. Recent evidence indicates that up to 18% of all extremely low-birth-weight infants will develop some degree of PH during their hospitalization, and the incidence rises to 25–40% of the infants with established BPD. Risk factors are not yet well understood, but new evidence shows that fetal growth restriction is a significant predictor of PH. Echocardiography remains the primary method for evaluation of BPD-associated PH, and the development of standardized screening timelines and techniques for identification of infants with BPD-associated PH remains an important ongoing topic of investigation. The use of pulmonary vasodilator medications, such as nitric oxide, sildenafil, and others, in the BPD population is steadily growing, but additional studies are needed regarding their long-term safety and efficacy.
An update on pharmacologic approaches to bronchopulmonary dysplasia

Sailaja Ghanta, Kristen Tropea Leeman, and Helen Christou
Seminars In Perinatology 37 (2013)115–123
http://dx.doi.org/10.1053/j.semperi.2013.01.008

Bronchopulmonary dysplasia (BPD) is the most prevalent long-term morbidity in surviving extremely preterm infants and is linked to increased risk of reactive airways disease, pulmonary hypertension, post-neonatal mortality, and adverse neurodevelopmental outcomes. BPD affects approximately 20% of premature newborns, and up to 60% of premature infants born before completing 26 weeks of gestation. It is characterized by the need for assisted ventilation and/or supplemental oxygen at 36 weeks postmenstrual age. Approaches to prevention and treatment of BPD have evolved with improved understanding of its pathogenesis. This review will focus on recent advancements and detail current research in pharmacotherapy for BPD. The evidence for both current and potential future experimental therapies will be reviewed in detail. As our understanding of the complex and multifactorial pathophysiology of BPD changes, research into these current and future approaches must continue to evolve.

Methylxanthines

Diuretics and bronchodilators

Corticosteroids

Macrolide antibiotics

Recombinant human Clara cell 10-kilodalton protein(rhCC10)

Vitamin A

Surfactant

Leukotriene receptor antagonist

Pulmonary vasodilators

Skeletal and Muscle

Skeletal Stem Cells in Space and Time

Moustapha Kassem and Paolo Bianco
Cell Jan 15, 2015; 160: 17-19
http://dx.doi.org/10.1016/j.cell.2014.12.034

The nature, biological characteristics, and contribution to organ physiology of skeletal stem cells are not completely determined. Chan et al. and Worthley et al. demonstrate that a stem cell for skeletal tissues, and a system of more restricted, downstream progenitors, can be identified in mice and demonstrate its role in skeletal tissue maintenance and regeneration.

The groundbreaking concept that bone, cartilage, marrow adipocytes, and hematopoiesis-supporting stroma could originate from a common progenitor and putative stem cell was surprising at the time when it was formulated (Owen and Friedenstein, 1988). The putative stem cell, nonhematopoietic in nature, would be found in the postnatal bone marrow stroma, generate tissues previously thought of as foreign to each other, and support the turnover of tissues and organs that self-renew at a much slower rate compared to other tissues associated with stem cells (blood, epithelia). This concept also connected bone and bone marrow as parts of a single-organ system, implying their functional interplay. For many years, the evidence underpinning the concept has been incomplete.

While multipotency of stromal progenitors has been demonstrated by in vivo transplantation experiments, self-renewal, the defining property of a stem cell, has not been easily demonstrated until recently in humans (Sacchetti et al., 2007) and mice (Mendez-Ferrer et al., 2010). Meanwhile, a confusing and plethoric terminology has been introduced into the literature, which diverted and confounded the search for a skeletal stem cell and its physiological significance (Bianco et al., 2013).

Two studies in this issue of Cell (Chan et al., 2015; Worthley et al., 2015), using a combination of rigorous single-cell analyses and lineage tracing technologies, mark significant steps toward rectifying the course of skeletal stem cell discovery by making several important points, within and beyond skeletal physiology.

First, a stem cell for skeletal tissues, and a system of more restricted, downstream progenitors can in fact be identified and linked to defined phenotype(s) in the mouse. The system is framed conceptually, and approached experimentally, similar to the hematopoietic system.

Second, based on its assayable functions and potential, the stem cell at the top of the hierarchy is defined as a skeletal stem cell (SSC). As noted earlier (Sacchetti et al., 2007) (Bianco et al., 2013), this term clarifies, well beyond semantics, that the range of tissues that the self-renewing stromal progenitor (originally referred to as an ‘‘osteogenic’’ or ‘‘stromal’’ stem cell) (Owen and Friedenstein, 1988) can actually generate in vivo, overlaps with the range of tissues that make up the skeleton.

Third, these cells are spatially restricted, local residents of the bone/bone marrow organ. The systemic circulation is not a sizable contributor to their recruitment to locally deployed functions.

Fourth, a native skeletogenic potential is inherent to the system of progenitor/ stem cells found in the skeleton, and internally regulated by bone morphogenetic protein (BMP) signaling. This is reflected in the expression of regulators and antagonists of BMP signaling within the system, highlighting potential feedback mechanisms modulating expansion or quiescence of specific cell compartments.

Fifth, in cells isolated from other tissues, an assayable skeletogenic potential is not inherent: it can only be induced de novo by BMP reprogramming. These two studies (Chan et al., 2015, Worthley et al., 2015) corroborate the classical concept of ‘‘determined’’ and ‘‘inducible’’ skeletal progenitors (Owen and Friedenstein, 1988): the former residing in the skeleton, the latter found in nonskeletal tissues; the former capable of generating skeletal tissues, in vivo and spontaneously, the latter requiring reprogramming signals in order to acquire a skeletogenic capacity; the former operating in physiological bone formation, the latter in unwanted, ectopic bone formation in diseases such as fibrodysplasia ossificans progressiva.

To optimize our ability to obtain specific skeletal tissues for medical application, the study by Chan et al. offers a glimpse of another facet of the biology of SSC lineages and progenitors. Chan et al. show that a homogeneous cell population inherently committed to chondrogenesis can alter its output to generate bone if cotransplanted with multipotent progenitors. Conversely, osteogenic cells can be shifted to a chondrogenic fate by blockade of vascular endothelial growth factor receptor, consistent with the avascular and hypoxic milieu of cartilage. This has two important implications:

commitment is flexible in the system;
the choir is as important as the soloist and can modulate the solo tune.

Reversibility and population behavior thus emerge as two features that may be characteristic, albeit not unique, of the stromal system, resonating with conceptually comparable evidence in the human system.

The two studies by Chan et al. and Worthely et al. emphasize the relevance not only of their new data, but also of a proper concept of a skeletal stem cell per se, for proper clinical use. Confusion arising from improper conceptualization of skeletal stem cells has markedly limited clinical development of skeletal stem cell biology.

Gremlin 1 Identifies a Skeletal Stem Cell with Bone, Cartilage, and Reticular Stromal Potential

Daniel L. Worthley, Michael Churchill, Jocelyn T. Compton, Yagnesh Tailor, et al.
Cell, Jan 15, 2015; 160: 269–284
http://dx.doi.org/10.1016/j.cell.2014.11.042

The stem cells that maintain and repair the postnatal skeleton remain undefined. One model suggests that perisinusoidal mesenchymal stem cells (MSCs) give rise to osteoblasts, chondrocytes, marrow stromal cells, and adipocytes, although the existence of these cells has not been proven through fate-mapping experiments. We demonstrate here that expression of the bone morphogenetic protein (BMP) antagonist gremlin 1 defines a population of osteochondroreticular (OCR) stem cells in the bone marrow. OCR stem cells self-renew and generate osteoblasts, chondrocytes, and reticular marrow stromal cells, but not adipocytes. OCR stem cells are concentrated within the metaphysis of long bones not in the perisinusoidal space and are needed for bone development, bone remodeling, and fracture repair. Grem1 expression also identifies intestinal reticular stem cells (iRSCs) that are cells of origin for the periepithelial intestinal mesenchymal sheath. Grem1 expression identifies distinct connective tissue stem cells in both the bone (OCR stem cells) and the intestine (iRSCs).

Identification and Specification of the Mouse Skeletal Stem Cell

Charles K.F. Chan, Eun Young Seo, James Y. Chen, David Lo, A McArdle, et al.
Cell, Jan 15, 2015; 160: 285–298
http://dx.doi.org/10.1016/j.cell.2014.12.002

How are skeletal tissues derived from skeletal stem cells? Here, we map bone, cartilage, and stromal development from a population of highly pure, postnatal skeletal stem cells (mouse skeletal stem cells, mSSCs) to their downstream progenitors of bone, cartilage, and stromal tissue. We then investigated the transcriptome of the stem/progenitor cells for unique gene-expression patterns that would indicate potential regulators of mSSC lineage commitment. We demonstrate that mSSC niche factors can be potent inducers of osteogenesis, and several specific combinations of recombinant mSSC niche factors can activate mSSC genetic programs in situ, even in nonskeletal tissues, resulting in de novo formation of cartilage or bone and bone marrow stroma. Inducing mSSC formation with soluble factors and subsequently regulating the mSSC niche to specify its differentiation toward bone, cartilage, or stromal cells could represent a paradigm shift in the therapeutic regeneration of skeletal tissues.

Bone mesenchymal development

The bone-remodeling cycle

Nuclear receptor modulation – Role of coregulators in selective estrogen receptor modulator (SERM) actions

Qin Feng, Bert W. O’Malley
Steroids 90 (2014) 39–43
http://dx.doi.org/10.1016/j.steroids.2014.06.008

Selective estrogen receptor modulators (SERMs) are a class of small-molecule chemical compounds that bind to estrogen receptor (ER) ligand binding domain (LBD) with high affinity and selectively modulate ER transcriptional activity in a cell- and tissue-dependent manner. The prototype of SERMs is tamoxifen, which has agonist activity in bone, but has antagonist activity in breast. Tamoxifen can reduce the risk of breast cancer and, at same time, prevent osteoporosis in postmenopausal women. Tamoxifen is widely prescribed for treatment and prevention of breast cancer. Mechanistically the activity of SERMs is determined by the selective recruitment of coactivators and corepressors in different cell types and tissues. Therefore, understanding the coregulator function is the key to understanding the tissue selective activity of SERMs.

Hematopoietic

Hematopoietic Stem Cell Arrival Triggers Dynamic Remodeling of the Perivascular Niche

Owen J. Tamplin, Ellen M. Durand, Logan A. Carr, Sarah J. Childs, et al.
Cell, Jan 15, 2015; 160: 241–252
http://dx.doi.org/10.1016/j.cell.2014.12.032

Hematopoietic stem and progenitor cells (HSPCs) can reconstitute and sustain the entire blood system. We generated a highly specific transgenic reporter of HSPCs in zebrafish. This allowed us to perform high resolution live imaging on endogenous HSPCs not currently possible in mammalian bone marrow. Using this system, we have uncovered distinct interactions between single HSPCs and their niche. When an HSPC arrives in the perivascular niche, a group of endothelial cells remodel to form a surrounding pocket. This structure appears conserved in mouse fetal liver. Correlative light and electron microscopy revealed that endothelial cells surround a single HSPC attached to a single mesenchymal stromal cell. Live imaging showed that mesenchymal stromal cells anchor HSPCs and orient their divisions. A chemical genetic screen found that the compound lycorine promotes HSPC-niche interactions during development and ultimately expands the stem cell pool into adulthood. Our studies provide evidence for dynamic niche interactions upon stem cell colonization.

Neonatal anemia

Sanjay Aher, Kedar Malwatkar, Sandeep Kadam
Seminars in Fetal & Neonatal Medicine (2008) 13, 239e247
http://dx.doi.org:/10.1016/j.siny.2008.02.009

Neonatal anemia and the need for red blood cell (RBC) transfusions are very common in neonatal intensive care units. Neonatal anemia can be due to blood loss, decreased RBC production, or increased destruction of erythrocytes. Physiologic anemia of the newborn and anemia of prematurity are the two most common causes of anemia in neonates. Phlebotomy losses result in much of the anemia seen in extremely low birthweight infants (ELBW). Accepting a lower threshold level for transfusion in ELBW infants can prevent these infants being exposed to multiple donors.

Management of anemia in the newborn

Naomi L.C. Luban
Early Human Development (2008) 84, 493–498
http://dx.doi.org:/10.1016/j.earlhumdev.2008.06.007

Red blood cell (RBC) transfusions are administered to neonates and premature infants using poorly defined indications that may result in unintentional adverse consequences. Blood products are often manipulated to limit potential adverse events, and meet the unique needs of neonates with specific diagnoses. Selection of RBCs for small volume (5–20 mL/kg) transfusions and for massive transfusion, defined as extracorporeal bypass and exchange transfusions, are of particular concern to neonatologists. Mechanisms and therapeutic treatments to avoid transfusion are another area of significant investigation. RBCs collected in anticoagulant additive solutions and administered in small aliquots to neonates over the shelf life of the product can decrease donor exposure and has supplanted the use of fresh RBCs where each transfusion resulted in a donor exposure. The safety of this practice has been documented and procedures established to aid transfusion services in ensuring that these products are available. Less well established are the indications for transfusion in this population; hemoglobin or hematocrit alone are insufficient indications unless clinical criteria (e.g. oxygen desaturation, apnea and bradycardia, poor weight gain) also augment the justification to transfuse. Comorbidities increase oxygen consumption demands in these infants and include bronchopulmonary dysplasia, rapid growth and cardiac dysfunction. Noninvasive methods or assays have been developed to measure tissue oxygenation; however, a true measure of peripheral oxygen offloading is needed to improve transfusion practice and determine the value of recombinant products that stimulate erythropoiesis. The development of such noninvasive methods is especially important since randomized, controlled clinical trials to support specific practices are often lacking, due at least in part, to the difficulty of performing such studies in tiny infants.
The Effect of Blood Transfusion on the Hemoglobin Oxygen Dissociation Curve of Very Early Preterm Infants During the First Week of Life

Virginie De HaUeux, Anita Truttmann, Carmen Gagnon, and Harry Bard
Seminars in Perinatology, 2002; 26(6): 411-415
http://dx.doi.org:/10.1053/sper.2002.37313

This study was conducted during the first week of life to determine the changes in Ps0 (PO2 required to achieve a saturation of 50% at pH 7.4 and 37~ and the proportions of fetal hemoglobin (I-IbF) and adult hemoglobin (HbA) prior to and after transfusion in very early preterm infants. Eleven infants with a gestational age <–27 weeks have been included in study. The hemoglobin dissociation curve and the Ps0 was determined by Hemox-analyser. Liquid chromatography was also performed to determine the proportions of HbF and HbA. The mean gestational age of the 11 infants was 25.1 weeks (-+1 weeks) and their mean birth weight was 736 g (-+125 g). They received 26.9 mL/kg of packed red cells. The mean Ps0 prior and after transfusion was 18.5 +- 0.8 and 21.0 + 1 mm Hg (P = .0003) while the mean percentage of HbF was 92.9 -+ 1.1 and 42.6 -+ 5.7%, respectively. The data of this study show a decrease of hemoglobin oxygen affinity as a result of blood transfusion in very early preterm infants prone to O 2 toxicity. The shift in HbO 2 curve after transfusion should be taken into consideration when oxygen therapy is being regulated for these infants.

Effect of neonatal hemoglobin concentration on long-term outcome of infants affected by fetomaternal hemorrhage

Mizuho Kadooka, H Katob, A Kato, S Ibara, H Minakami, Yuko Maruyama
Early Human Development 90 (2014) 431–434
http://dx.doi.org/10.1016/j.earlhumdev.2014.05.010

Background: Fetomaternal hemorrhage (FMH) can cause severe morbidity. However, perinatal risk factors for long-term poor outcome due to FMH have not been extensively studied. Aims: To determine which FMH infants are likely to have neurological sequelae.
Study design: A single-center retrospective observational study. Perinatal factors, including demographic characteristics, Kleihauer–Betke test, blood gas analysis, and neonatal blood hemoglobin concentration ([Hb]), were analyzed in association with long-term outcomes.
Subjects: All 18 neonates referred to a Neonatal Intensive Care Unit of Kagoshima City Hospital and diagnosed with FMH during a 15-year study period. All had a neonatal [Hb] b7.5 g/dL and 15 of 17 neonates tested had Kleihauer–Betke test result N4.0%.
Outcome measures: Poor long-term outcome was defined as any of the following determined at 12 month old or more: cerebral palsy, mental retardation, attention deficit/hyperactivity disorder, and epilepsy.
Results: Nine of the 18 neonates exhibited poor outcomes. Among demographic characteristics and blood variables compared between two groups with poor and favorable outcomes, significant differences were observed in [Hb] (3.6 ± 1.4 vs. 5.4 ± 1.1 g/dL, P = 0.01), pH (7.09 ± 0.11 vs. 7.25 ± 0.13, P = 0.02) and base deficits (17.5 ± 5.4 vs. 10.4 ± 6.0 mmol/L, P = 0.02) in neonatal blood, and a number of infants with [Hb] ≤ 4.5 g/dL (78%[7/9] vs. 22%[2/9], P= 0.03), respectively. The base deficit in neonatal arterial blood increased significantly with decreasing neonatal [Hb].
Conclusions: Severe anemia causing severe base deficit is associated with neurological sequelae in FMH infants

Clinical and hematological presentation among Indian patients with common hemoglobin variants

Khushnooma Italia, Dipti Upadhye, Pooja Dabke, Harshada Kangane, et al.
Clinica Chimica Acta 431 (2014) 46–51
http://dx.doi.org/10.1016/j.cca.2014.01.028

Background: Co-inheritance of structural hemoglobin variants like HbS, HbD Punjab and HbE can lead to a variable clinical presentation and only few cases have been described so far in the Indian population.
Methods: We present the varied clinical and hematological presentation of 22 cases (HbSD Punjab disease-15, HbSE disease-4, HbD Punjab E disease-3) referred to us for diagnosis.
Results: Two of the 15 HbSDPunjab disease patients had moderate crisis, one presented with mild hemolytic anemia; however, the other 12 patients had a severe clinical presentation with frequent blood transfusion requirements, vaso occlusive crisis, avascular necrosis of the femur and febrile illness. The 4 HbSE disease patients had a mild to moderate presentation. Two of the 3 HbD Punjab E patients were asymptomatic with one patient’s sibling having a mild presentation. The hemoglobin levels of the HbSD Punjab disease patients ranged from 2.3 to 8.5 g/dl and MCV from 76.3 to 111.6 fl. The hemoglobin levels of the HbD Punjab E and HbSE patients ranged from 10.8 to 11.9 and 9.8 to 10.0 g/dl whereas MCV ranged from 67.1 to 78.2 and 74.5 to 76.0 fl respectively.
Conclusions: HbSD Punjab disease patients should be identified during newborn screening programs and managed in a way similar to sickle cell disease. Couple at risk of having HbSD Punjab disease children may be given the option of prenatal diagnosis in subsequent pregnancies.

Sickle cell anemia is the most common hemoglobinopathy seen across the world. It is caused by a point mutation in the 6th codon of the beta (β) globin gene leading to the substitution of the amino acid glutamic acid to valine. The sickle gene is frequently seen in Africa, some Mediterranean countries, India, Middle East—Saudi Arabia and North America. In India the prevalence of hemoglobin S (HbS) carriers varies from 2 to 40% among different population groups and HbS is mainly seen among the scheduled tribe, scheduled caste and other backward class populations in the western, central and parts of eastern and southern India. Sickle cell anemia has a variable clinical presentation in India with the most severe clinical presentation seen in central India whereas patients in the western region show a mild to moderate clinical presentation.

Hemoglobin D Punjab (HbD Punjab) (also known as HbD Los-Angeles, HbD Portugal, HbD North Carolina, D Oak Ridge and D Chicago) is another hemoglobin variant due to a point mutation in codon 121 of the β globin gene resulting in the substitution of the amino acid glutamic acid to glycine. It is a widely distributed hemoglobin with a relatively low prevalence of 0.86% in the Indo-Pak subcontinent, 1–3% in north-western India, 1–3% in the Black population in the Caribbean and North America and has also been reported among the English. It accounts for 55.6% of all the Hb variants seen in the Xenjiang province of China.

Hemoglobin E (HbE) is the most common abnormal hemoglobin in Southeast Asia. In India, the frequency ranges from 4% to 51% in the north eastern region and 3% to 4% in West Bengal in the east. The HbE mutation (β26 GAG→AAG) creates an alternative splice site and the βE chain is insufficiently synthesized, hence the phenotype of this disorder is that of a mild form of β thalassemia.

Though these 3 structural variants are prevalent in different regions of India, their interaction is increasingly seen in all states of the country due to migration of people to different regions for a better livelihood. There are very few reports on interaction of these commonly seen Hb variants and the phenotypic–genotypic presentation of these cases is important for genetic counseling and management.

HbF of patients with HbSD Punjab disease with variable clinical severity. The HbF values of 4 patients are not included as they were post blood transfusion

The genotypes of the patients were confirmed by restriction enzyme digestion and ARMS (Fig). Patients 1 to 15 were characterized as compound heterozygous for HbS and HbD Punjab whereas patients 16 to 19 were characterized as compound heterozygous for HbS and HbE. Patient nos. 20 to 22 were characterized as compound heterozygous for HbE and HbD Punjab.

Molecular characterization of HbS and HbDPunjab by restriction enzyme digestion and of HbE by ARMS.

The 3 common β globin gene variants of hemoglobin, HbS, HbE and HbD Punjab are commonly seen in India, with HbS having a high prevalence in the central belt and some parts of western, eastern and southern India, HbE in the eastern and north eastern region whereas HbD is mostly seen in the north western part of India. These hemoglobin variants have been reported in different population groups. However, with migration and intermixing of the different populations from different geographic regions, occasional cases of HbSD Punjab and HbSE are being reported. There are several HbD variants like HbD Punjab, HbD Iran, HbD Ibadan. However, of these only HbD Punjab interacts with HbS to form a clinically significant condition as the glutamine residue facilitates polymerization of HbS. HbD Iran and HbD Ibadan are non-interacting and produce benign conditions like the sickle cell trait. The first case of HbSD Punjab disease was a brother and sister considered to have atypical sickle cell disease in 1934. This family was further reinvestigated and reported as the first case of HbD Los Angeles which has the same mutation as the HbD Punjab. Serjeant et al. reported HbD Punjab in an English parent in 6 out of 11 HbSD-Punjab disease cases. This has been suggested to be due to the stationing of nearly 50,000 British troops on the Indian continent for a period of 200 y and the introduction into Britain of their Anglo-Indian children.

HbSD Punjab disease shows a similar pattern to HbS homozygous on alkaline hemoglobin electrophoresis but can be differentiated on acid agar gel electrophoresis and on HPLC. In HbSD Punjab disease cases, the peripheral blood films show anisocytosis, poikilocytosis, target cells and irreversibly sickled cells. Values of HbF and HbA2 are similar to those in sickle homozygous cases. HbSD Punjab disease is characterized by a moderately severe hemolytic anemia.

Twenty-one cases of HbSDPunjab were reported by Serjeant of which 16 were reported by different workers among patients originating from Caucasian, Spanish, Australian, Irish, English, Portuguese, Black, American, Venezuelan, Caribbean, Mexican, Turkish and Jamaican backgrounds. Yavarian et al. 2009 reported a multi centric origin of HbD Punjab which in combination with HbS results in sickle cell disease. Patel et al. 2010 have also reported 12 cases of HbSD Punjab from the Orissa state of eastern India. Majority of these cases were symptomatic, presenting with chronic hemolytic anemia and frequent painful crises.

HbF levels >20% were seen in 4 out of our 11 clinically severe patients of HbSD-Punjab disease with the mean HbF levels of 16.8% in 8 clinically severe patients, while 3 clinically severe patients were post transfused. However, the 3 patients with a mild to moderate clinical presentation showed a mean HbF level of 8.6%. This is in contrast to the relatively milder clinical presentation associated with high HbF seen in patients with sickle cell anemia. This was also reported by Adekile et al. 2010 in 5 cases of HbS-DLos Angeles where high HbF did not ameliorate the severe clinical presentation seen in these patients.

These 15 cases of HbSD^Punjab disease give us an overall idea of the severe clinical presentation of the disease in different regions of India. However the HbD^PunjabE cases were milder or asymptomatic and the HbSE cases were moderately symptomatic. Since most of the cases of HbSD^Punjab disease were clinically severe, it is important to pick up these cases during newborn screening and enroll them into a comprehensive care program with the other sickle cell disease patients with introduction of therapeutic interventions such as penicillin prophylaxis if required and pneumococcal immunization. In fact, 2 of our cases (No. 6 and 7) were identified during newborn screening for sickle cell disorders. The parents can be given information on home care and educated to detect symptoms that may lead to serious medical emergencies. The parents of these patients as well as the couples who are at risk of having a child with HbSD^Punjab disease could also be counseled about the option of prenatal diagnosis in subsequent pregnancies. It is thus important to document the clinical and hematological presentation of compound heterozygotes with these common β globin chain variants.

Common Hematologic Problems in the Newborn Nursery

Jon F. Watchko
Pediatr Clin N Am – (2015) xxx-xxx
http://dx.doi.org/10.1016/j.pcl.2014.11.011

Common RBC disorders include hemolytic disease of the newborn, anemia, and polycythemia. Another clinically relevant hematologic issue in neonates to be covered herein is thrombocytopenia. Disorders of white blood cells will not be reviewed.

KEY POINTS

(1) Early clinical jaundice or rapidly developing hyperbilirubinemia are often signs of hemolysis, the differential diagnosis of which commonly includes immune-mediated disorders, red-cell enzyme deficiencies, and red-cell membrane defects.

(2) Knowledge of the maternal blood type and antibody screen is critical in identifying non-ABO alloantibodies in the maternal serum that may pose a risk for severe hemolytic disease in the newborn.

(3) Moderate to severe thrombocytopenia in an otherwise well-appearing newborn strongly suggests immune-mediated (alloimmune or autoimmune) thrombocytopenia.

Hemolytic conditions in the neonate

1. Immune-mediated (positive direct Coombs test) a. Rhesus blood group: Anti-D, -c, -C, -e, -E, CW, and several others

b. Non-Rhesus blood groups: Kell, Duffy, Kidd, Xg, Lewis, MNS, and others

c. ABO blood group: Anti-A, -B

2. Red blood cell (RBC) enzyme defects

a. Glucose-6-phosphate dehydrogenase (G6PD) deficiency

b. Pyruvate kinase deficiency

c. Others

3. RBC membrane defects

a. Hereditary spherocytosis

b. Elliptocytosis

c. Stomatocytosis

d. Pyknocytosis

e. Others

4. Hemoglobinopathies

a. alpha-thalassemia

b. gamma-thalassemia

Standard maternal antibody screeningAlloantibody Blood Group

D, C, c, E, e, f, CW, V Rhesus

K, k, Kpa, Jsa Kell

Fya, Fyb Duffy

Jka, Jkb Kidd

Xga Xg

Lea, Leb Lewis

S, s, M, N MNS

P1 P

Lub Lutheran

Non-ABO alloantibodies reported to cause moderate to severe hemolytic disease of the newbornWithin Rh system: Anti-D, -c, -C, -Cw, -Cx, -e, -E, -Ew, -ce, -Ces, -Rh29, -Rh32, -Rh42, -f, -G, -Goa, -Bea, -Evans, -Rh17, -Hro, -Hr, -Tar, -Sec, -JAL, -STEM

Outside Rh system: Anti-LW, -K, -k, -Kpa, -Kpb, -Jka, -Jsa, -Jsb, -Ku, -K11, -K22, -Fya, -M, -N, -S, -s, -U, -PP1 pk, -Dib, -Far, -MUT, -En3, -Hut, -Hil, -Vel, -MAM, -JONES, -HJK, -REIT

Red Blood Cell Enzymopathies

G6PD9 and pyruvate kinase (PK) deficiency are the 2 most common red-cell enzyme disorders associated with marked neonatal hyperbilirubinemia. Of these, G6PD deficiency is the more frequently encountered and it remains an important cause of kernicterus worldwide, including the United States, Canada, and the United Kingdom, the prevalence in Western countries a reflection in part of immigration patterns and intermarriage. The risk of kernicterus in G6PD deficiency also relates to the potential for unexpected rapidly developing extreme hyperbilirubinemia in this disorder associated with acute severe hemolysis.

Red Blood Cell Membrane Defects

Establishing a diagnosis of RBC membrane defects is classically based on the development of Coombs-negative hyperbilirubinemia, a positive family history, and abnormal RBC smear, albeit it is often difficult because newborns normally exhibit a marked variation in red-cell membrane size and shape. Spherocytes, however, are not often seen on RBC smears of hematologically normal newborns and this morphologic abnormality, when prominent, may yield a diagnosis of hereditary spherocytosis (HS) in the immediate neonatal period. Given that approximately 75% of families affected with hereditary spherocytosis manifest an autosomal dominant phenotype, a positive family history can often be elicited and provide further support for this diagnosis. More recently, Christensen and Henry highlighted the use of an elevated mean corpuscular hemoglobin concentration (MCHC) (>36.0 g/dL) and/or elevated ratio of MCHC to mean corpuscular volume, the latter they term the “neonatal HS index” (>0.36, likely >0.40) as screening tools for HS. An index of greater than 0.36 had 97% sensitivity, greater than 99% specificity, and greater than 99% negative predictive value for identifying HS in neonates. Christensen and colleagues also provided a concise update of morphologic RBC features that may be helpful in diagnosing this and other underlying hemolytic conditions in newborns.

The diagnosis of HS can be confirmed using the incubated osmotic fragility test when coupled with fetal red-cell controls or eosin-5-maleimide flow cytometry. One must rule out symptomatic ABO hemolytic disease by performing a direct Coombs test, as infants so affected also may manifest prominent micro-spherocytosis. Moreover, HS and symptomatic ABO hemolytic disease can occur in the same infant and result in severe hyperbilirubinemia and anemia. Of other red-cell membrane defects, only hereditary elliptocytosis, stomato-cytosis, and infantile pyknocytosis have been reported to exhibit significant hemolysis in the newborn period. Hereditary elliptocytosis and stomatocytosis are both rare. Infantile pyknocytosis, a transient red-cell membrane abnormality manifesting itself during the first few months of life, is more common.

Risk factors for bilirubin neurotoxicityIsoimmune hemolytic disease

G6PD deficiency

Asphyxia

Sepsis

Acidosis

Albumin less than 3.0 g/dL
Data from Maisels MJ, Bhutani VK, Bogen D, et al. Hyperbilirubinemia in the newborn infant > or 535 weeks’ gestation: an update with clarifications. Pediatrics 2009; 124:1193–8.

Polycythemia

Polycythemia (venous hematocrit 65%) in seen in infants across a range of conditions associated with active erythropoiesis or passive transfusion.76,77 They include, among others, placental insufficiency, the infant of a diabetic mother, recipient in twin-twin transfusion syndrome, and several aneuploidies, including trisomy. The clinical concern related to polycythemia is the risk for microcirculatory complications of hyperviscosity. However, determining which polycythemic infants are hyperviscous and when to intervene is a challenge.

Liver

Metabolic disorders presenting as liver disease

Germaine Pierre, Efstathia Chronopoulou
Paediatrics and Child Health 2013; 23(12): 509-514
The liver is a highly metabolically active organ and many inherited metabolic disorders have hepatic manifestations. The clinical presentation in these patients cannot usually be distinguished from liver disease due to acquired causes like infection, drugs or hematological disorders. Manifestations include acute and chronic liver failure, cholestasis and hepatomegaly. Metabolic causes of acute liver failure in childhood can be as high as 35%. Certain disorders like citrin deficiency and Niemann-Pick C disease may present in infancy with self-limiting cholestasis before presenting in later childhood or adulthood with irreversible disease. This article reviews important details from the history and clinical examination when evaluating the pediatric patient with suspected metabolic disease, the specialist and genetic tests when investigating, and also discusses specific disorders, their clinical course and treatment. The role of liver transplantation is also briefly discussed. Increased awareness of this group of disorders is important as in many cases, early diagnosis leads to early intervention with improved outcome. Diagnosis also allows genetic counselling and future family planning.

Adult liver disorders caused by inborn errors of metabolism: Review and update

Sirisak Chanprasert, Fernando Scaglia
Molecular Genetics and Metabolism 114 (2015) 1–10
http://dx.doi.org/10.1016/j.ymgme.2014.10.011

Inborn errors of metabolism (IEMs) are a group of genetic diseases that have protean clinical manifestations and can involve several organ systems. The age of onset is highly variable but IEMs afflict mostly the pediatric population. However, in the past decades, the advancement in management and new therapeutic approaches have led to the improvement in IEM patient care. As a result, many patients with IEMs are surviving into adulthood and developing their own set of complications. In addition, some IEMs will present in adulthood. It is important for internists to have the knowledge and be familiar with these conditions because it is predicted that more and more adult patients with IEMs will need continuity of care in the near future. The review will focus on Wilson disease, alpha-1 antitrypsin deficiency, citrin deficiency, and HFE-associated hemochromatosis which are typically found in the adult population. Clinical manifestations and pathophysiology, particularly those that relate to hepatic disease as well as diagnosis and management will be discussed in detail.

Inborn errors of metabolism (IEMs) are a group of genetic diseases characterized by abnormal processing of biochemical reactions, resulting in accumulation of toxic substances that could interfere with normal organ functions, and failure to synthesize essential compounds. IEMs are individually rare, but collectively numerous. The clinical presentations cover a broad spectrum and can involve almost any organ system. The age of onset is highly variable but IEMs afflict mostly the pediatric population.

Wilson disease is an autosomal recessive genetic disorder of copper metabolism. It is characterized by an abnormal accumulation of inorganic copper in various tissues, most notably in the liver and the brain, especially in the basal ganglia. The disease was first described in 1912 by Kinnier Wilson, and affects between 1 in 30,000 and 1 in 100,000 individuals. Clinical features are variable and depend on the extent and the severity of copper deposition. Typically, patients tend to develop hepatic disease at a younger age than the neuropsychiatric manifestations. Individuals withWilson disease eventually succumb to complications of end stage liver disease or become debilitated from neurological problems, if they are left untreated.

The clinical presentations of Wilson disease are varied affecting many organ systems. However, the overwhelming majority of cases display hepatic and neurologic symptoms. In general, patients with hepatic disease present between the first and second decades of life although patients as young as 3 years old or over 50 years old have also been reported. The most common modes of presentations are acute self-limited hepatitis and chronic active hepatitis that are indistinguishable from other hepatic disorders although liver aminotransferases are generally much lower than in autoimmune or viral hepatitis. Acute fulminant hepatic failure is less common but is observed in approximately 3% of all cases of acute liver failure. Symptoms of acute liver failure include jaundice, coagulopathy, and hepatic encephalopathy. Cirrhosis can develop over time and may be clinically silent. Hepatocellular carcinoma (HCC) is rarely associated with Wilson disease, but may occur in the setting of cirrhosis and chronic inflammation.

Copper is an essential element, and is required for the proper functioning of various proteins and enzymes. The total body content of copper in a healthy adult individual is approximately 70–100 mg, while the daily requirements are estimated to be between 1 and 5 mg. Absorption occurs in the small intestine. Copper is taken up to the hepatocytes via the copper transporter hTR1. Once inside the cell, copper is bound to various proteins including metallothionein and glutathione, however, it is the metal chaperone, ATOX1 that helps direct copper to the ATP7B protein for intracellular transport and excretion. At the steady state, copper will be bound to ATP7B and is then incorporated to ceruloplasmin and secreted into the systemic circulation. When the cellular copper concentration arises, ATP7B protein will be redistributed from the trans-Golgi network to the prelysosomal vesicles facilitating copper excretion into the bile. The molecular defects in ATP7B lead to a reduction of copper excretion. Excess copper is accumulated in the liver causing tissue injury. The rate of accumulation of copper varies among individuals, and it may depend on other factors such as alcohol consumption, or viral hepatitis infections. If the liver damage is not severe, patients will accumulate copper in various tissues including the brain, the kidney, the eyes, and the musculoskeletal system leading to clinical disease. A failure of copper to incorporate into ceruloplasmin leads to secretion of the unsteady protein that has a shorter half-life, resulting in the reduced concentrations of ceruloplasmin seen in most patients with Wilson disease.

Wilson disease used to be a progressive fatal condition during the first half of the 20th century because there was no effective treatment available at that time. Penicillamine was the first pharmacologic agent introduced in 1956 for treating this condition. Penicillamine is a sulfhydryl-bearing amino acid cysteine doubly substituted with methyl groups. This drug acts as a chelating agent that promotes the urinary excretion of copper. It is rapidly absorbed in the gastrointestinal track, and over 80% of circulating penicillamine is excreted via the kidneys. Although it is very effective, approximately 10%–50% of Wilson disease patients with neuropsychiatric presentations may experience worsening of their symptoms, and often times the worsening symptoms may not be reversible.

Alpha1-antitrypsin deficiency

Alpha1-antitrypsin deficiency (AATD) is one of the most common genetic liver diseases in children and adults, affecting 1 in 2000 to 1 in 3000 live births worldwide. It is transmitted in an autosomal co-dominant fashion with variable expressivity. Alpha1 antitrypsin (A1AT) is a member of the serine protease inhibitor (SERPIN) family. Its function is to counteract the proteolytic effect of neutrophil elastase and other neutrophil proteases. Mutations in the SERPINA1, the gene encoding A1AT, result in changes in the protein structure with the PiZZ phenotype being the most common cause of liver and lung disease-associated AATDs. Although, it classically causes early onset chronic obstructive pulmonary disease (COPD) in adults, liver disease characterized by chronic inflammation, hepatic fibrosis, and cirrhosis is not uncommon in the adult population. Decreased plasma concentration of A1AT predisposes lung tissue to be more susceptible to injury from protease enzymes. However, the underlying mechanism of liver injury is different, and is believed to be caused by accumulation of polymerized mutant A1AT in the hepatocyte endoplasmic reticulum (ER). Currently, there is no specific treatment for liver disease-associated AATD, but A1AT augmentation therapy is available for patients affected with pulmonary involvement.

A1AT is a single-chain, 52-kDa polypeptide of approximately 394 amino acids [56]. It is synthesized in the liver, circulates in the plasma, and functions as an inhibitor of neutrophil elastase and other proteases such as cathepsin G, and proteinase 3. A1AT has a globular shape composed of two central β sheets surrounded by a small β sheet and nine α helices. The pathophysiology underlying liver disease is thought to be a toxic gain-of-function mutation associated with the PiZZ phenotypes. This hypothesis has been supported by the fact that null alleles which produce no detectable plasma A1AT, are not associated with liver disease. In addition, the transgenic mouse model of AATD PiZZ developed periodic acid-Schiff-positive diastase-resistant intrahepatic globule early in life similar to AATD patients. The PiZZ phenotype results in the blockade of the final processing of A1AT in the liver, as only 15% of the A1AT reaches the circulation whereas 85% of non-secreted protein is accumulated in the hepatocytes.

Citrin deficiency

Citrin deficiency is a relatively newly-defined autosomal recessive disease. It encompasses two different sub-groups of patients, neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), and adult onset citrullinemia type 2 (CTLN 2).

AGC2 exports aspartate out of the mitochondrial matrix in exchange for glutamate and a proton. Thus, this protein has an important role in ureagenesis and gluconeogenesis. In CTLN2, a defect in this protein is believed to limit the supply of aspartate for the formation of argininosuccinate in the cytosol resulting in impairment of ureagenesis. Interestingly, the mouse model of citrin deficiency (Ctrn−/−) fails to develop symptoms of CTLN2 suggesting that the mitochondrial aspartate is not the only source of ureagenesis. However, it should be noted that the rodent liver expresses higher glycerol-phosphate shuttle activity than the human counterpart. With the intact glycerol-phosphate dehydrogenase, it can compensate for the deficiency of AGC2, as demonstrated by the AGC2 and glycerol-phosphate dehydrogenase double knock-out mice that exhibit similar features to those observed in human CTLN2.

HFE-associated hemochromatosis

HFE-associated hemochromatosis is an inborn error of iron metabolism characterized by excessive iron storage resulting in tissue and organ damage. It is the most common autosomal recessive disorder in the Caucasian population, affecting 0.3%–0.5% of individuals of Northern European descent. The term “hemochromatosis” was coined in 1889 by the German pathologist Friedrich Daniel Von Recklinghausen, who described it as bronze stain of organs caused by a blood borne pigment.

The classic clinical triad of cirrhosis, diabetes, and bronze skin pigmentation is rarely observed nowadays given the early recognition, diagnosis, and treatment of this condition. The most common presenting symptoms are nonspecific including weakness, lethargy, and arthralgia.

The liver is a major site of iron storage in healthy individuals and as such it is the organ that is universally affected in HFE-associated hemochromatosis. Elevation of liver aminotransferases indicative of hepatocyte injury is the most common mode of presentation and it can be indistinguishable from other causes of hepatitis. Approximately 15%–40% of patients with HFE-associated hemochromatosis have other liver conditions, including chronic viral hepatitis B or C infection, nonalcoholic fatty liver disease, and alcoholic liver disease.

The liver in haemochromatosis

Rune J. Ulvik
Journal of Trace Elements in Medicine and Biology xxx (2014) xxx–xxx
http://dx.doi.org/10.1016/j.jtemb.2014.08.005

The review deals with genetic, regulatory and clinical aspects of iron homeostasis and hereditary hemochromatosis. Hemochromatosis was first described in the second half of the 19th century as a clinical entity characterized by excessive iron overload in the liver. Later, increased absorption of iron from the diet was identified as the pathophysiological hallmark. In the 1970s genetic evidence emerged supporting the apparent inheritable feature of the disease. And finally in 1996 a new “hemochromato-sis gene” called HFE was described which was mutated in about 85% of the patients. From the year2000 onward remarkable progress was made in revealing the complex molecular regulation of iron trafficking in the human body and its disturbance in hemochromatosis. The discovery of hepcidin and ferroportin and their interaction in regulating the release of iron from enterocytes and macrophages to plasma were important milestones. The discovery of new, rare variants of non-HFE-hemochromatosis was explained by mutations in the multicomponent signal transduction pathway controlling hepcidin transcription. Inhibited transcription induced by the altered function of mutated gene products, results in low plasma levels of hepcidin which facilitate entry of iron from enterocytes into plasma. In time this leads to progressive accumulation of iron and subsequently development of disease in the liver and other parenchymatous organs. Being the major site of excess iron storage and hepcidin synthesis the liver is a cornerstone in maintaining normal systemic iron homeostasis. Its central pathophysiological role in HFE-hemochromatosis with downgraded hepcidin synthesis, was recently shown by the finding that liver transplantation normalized the hepcidin levels in plasma and there was no sign of iron accumulation in the new liver.

Gastrointestinal

Decoding the enigma of necrotizing enterocolitis in premature infants

Roberto Murgas Torrazza, Nan Li, Josef Neu
Pathophysiology 21 (2014) 21–27
http://dx.doi.org/10.1016/j.pathophys.2013.11.011

Necrotizing enterocolitis (NEC) is an enigmatic disease that affects primarily premature infants. It often occurs suddenly and when it occurs, treatment attempts at treatment often fail and results in death. If the infant survives, there is a significant risk of long term sequelae including neurodevelopmental delays. The pathophysiology of NEC is poorly understood and thus prevention has been difficult. In this review, we will provide an overview of why progress may be slow in our understanding of this disease, provide a brief review diagnosis, treatment and some of the current concepts about the pathophysiology of this disease.

Necrotizing enterocolitis (NEC) has been reported since special care units began to house preterm infants .With the advent of modern neonatal intensive care approximately 40 years ago, the occurrence and recognition of the disease markedly increased. It is currently the most common and deadly gastro-intestinal illness seen in preterm infants. Despite major efforts to better understand, treat and prevent this devastating disease, little if any progress has been made during these 4 decades. Underlying this lack of progress is the fact that what is termed “NEC” is likely more than one disease, or mimicked by other diseases, each with a different etiopathogenesis.

Human gut microbiome

Term or near term infants with “NEC” when compared to matched controls usually have occurrence of their disease in the first week after birth, have a significantly higher frequency of prolonged rupture of membranes, chorio-amnionitis, Apgar score <7 at 1 and 5 min, respiratory problems, congenital heart disease, hypoglycemia, and exchange transfusions. When a “NEC” like illness presents in term or near term infants, it should be noted that these are likely to be distinct in pathogenesis than the most common form of NEC and should be differentiated as such.

The infants who suffer primary ischemic necrosis are term or near term infants (although this can occur in preterms) who have concomitant congenital heart disease, often related to poor left ventricular output or obstruction. Other factors that have been associated with primary ischemia are maternal cocaine use, hyperviscosity caused by polycythemia or a severe antecedent hypoxic–ischemic event. Whether the dis-ease entity that results from this should be termed NEC can be debated on historical grounds, but the etiology is clearly different from the NEC seen in most preterm infants.

The pathogenesis of NEC is uncertain, and the etiology seems to be multifactorial. The “classic” form of NEC is highly associated with prematurity; intestinal barrier immaturity, immature immune response, and an immature regulation of intestinal blood flow (Fig.). Although genetics appears to play a role, the environment, especially a dysbiotic intestinal microbiota acting in concert with host immaturities predisposes the preterm infant to disruption of the intestinal epithelia, increased permeability of tight junctions, and release of inflammatory mediators that leads to intestinal mucosa injury and therefore development of necrotizing enterocolitis.

NEC is a multifactorial disease

What causes NEC? NEC is a multifactorial disease with an interaction of several etiophathologies

It is clear from this review that there are several entities that have been described as NEC. What is also clear is that despite having some overlap in the final parts of the pathophysiologic cascade that lead to necrosis, the disease that is most commonly seen in the preterm infant is likely to have an origin that differs markedly from that seen in term infants with congenital heart disease or severe hypoxic–ischemic injury. Thus, epidemiologic studies will need to differentiate these entities, if the aim is to dissect common features that are most highly associated with development of the disease. At this juncture, we areleft with more of a population based preventative approach, where the use of human milk, evidence based feeding guide-lines, considerations for microbial therapy once these are proved safe and effective and approved as such by regulatory authorities, and perhaps even measures that prevent prematurity will have a major impact on this devastating disease.

Influenced by the microbiota, intestinal epithelial cells (IECs) elaborate cytokines

Influenced by the microbiota, intestinal epithelial cells (IECs) elaborate cytokines, including thymic stromal lymphoprotein (TSLP), transforming growthfactor (TGF), and interleukin-10 (IL-10), that can influence pro-inflammatory cytokine production by dendritic cells (DC) and macrophages present in the laminapropria (GALT) and Peyer’s patches. Signals from commensal organisms may influence tissue-specific functions, resulting in T-cell expansion and regulation of the numbers of Th-1,
Th-2, and Th-3 cells. Also modulated by the microbiota, other IEC derived factors, including APRIL (a proliferation-inducing ligand),B-cell activating factor (BAFF), secretory leukocyte peptidase inhibitor (SLPI), prostaglandin E2(PGE2), and other metabolites, directly regulate functions ofboth antigen presenting cells and lymphocytes in the intestinal ecosystem. NK: natural killer cell; LN: lymph node; DC: dendritic cells.Modified from R. Sharma, C. Young, M. Mshvildadze, J. Neu, Intestinal microbiota does it play a role in diseases of the neonate? NeoReviews 10 (4) (2009)e166, with permission

Cross-talk between monocyte.macrophage cells and T.NK lymphocytes

Current Issues in the Management of Necrotizing Enterocolitis

Marion C. W. Henry and R. Lawrence Moss
Seminars in Perinatology, 2004; 28(3): 221-233
http://dx.doi.org:/10.1053/j.semperi.2004.03.010

Necrotizing enterocolitis is almost exclusively a disease of prematurity, with 90% of all cases occurring in premature infants and 90% of those infants weighing less than 2000 g. Prematurity is the only risk factor for necrotizing enterocolitis consistently identified in case control studies and the disease is rare in countries where prematurity is uncommon such as Japan and Sweden. When necrotizing enterocolitis does occur in full-term infants, it appears to by a somewhat different disease, typically associated with some predisposing condition.

NEC occurs in one to three in 1,000 live births and most commonly affects babies born between 30-32 weeks. It is most often diagnosed during the second week of life and occurs more often in previously fed infants. The mortality from NEC has been cited as 10% to 50% of all NEC cases. Surgical mortality has decreased over the last several decades from 70% to between 20 and 50%. The incremental cost per case of acute hospital care is estimated at $74 to 186 thousand compared to age matched controls, not including additional costs of long term care for the infants’ with lifelong morbidity. Survivors may develop short bowel syndrome, recurrent bouts of catheter-related sepsis, malabsorption, malnutrition, and TPN induced liver failure.

Although extensive research concerning the pathophysiology of necrotizing enterocolitis has occurred, a complete understanding has not been fully elucidated. The classic histologic finding is coagulation necrosis; present in over 90% of specimens. This finding suggests the importance of ischemia in the pathogenesis of NEC. Inflammation and bacterial overgrowth also are present. These findings support the assumptions by Kosloske that NEC occurs by the interaction of 3 events:

intestinal ischemia,
colonization by pathogenic bacteria and
excess protein substrate in the intestinal lumen.

Additionally, the immunologic immaturity of the neonatal gut has been implicated in the development of NEC. Reparative tissue changes including epithelial regeneration, formation of granulation tissue and fibrosis, and mixed areas of acute and chronic inflammatory changes suggest that the pathogenesis of NEC may involve a chronic process of injury and repair.

Premature newborns born prior to the 32^nd week of gestational age may have compromised intestinal peristalsis and decreased motility. These motility problems may lead to poor clearance of bacteria, and subsequent bacterial overgrowth. Premature infants also have an immature intestinal tract in terms of immunologic immunity.

There are fewer functional B lymphocytes present and the ability to produce sufficient secretory IgA is reduced. Pepsin, gastric acid and mucus are also not produced as well in prematurity. All of these factors may contribute to the limited proliferation of intestinal flora and the decreased binding of these flora to mucosal cells (Fig).

Role of nitric oxide in the pathogenesis of NEC

Role of nitric oxide in the pathogenesis of NEC.

Characteristics of the immature gut leading to increased risk of necrotizing enterocolitis

Characteristics of the immature gut leading to increased risk of necrotizing enterocolitis.

As understanding of the pathophysiology of necrotizing enterocolitis continues to evolve, a unifying concept is emerging. Initially, there is likely a subclinical insult leading to NEC. This may arise from a brief episode of hypoxia or infection. With colonization of the intestines, bacteria bind to the injured mucosa eliciting an inflammatory response which leads to further inflammation.

Intestinal Microbiota Development in Preterm Neonates and Effect of Perinatal Antibiotics

Silvia Arboleya, Borja Sanchez,, Christian Milani, Sabrina Duranti, et al.
Pediatr 2014;-:—). http://dx.doi.org/10.1016/j.jpeds.2014.09.041

Objectives Assess the establishment of the intestinal microbiota in very low birth-weight preterm infants and to evaluate the impact of perinatal factors, such as delivery mode and perinatal antibiotics.
Study design We used 16S ribosomal RNA gene sequence-based microbiota analysis and quantitative polymerase chain reaction to evaluate the establishment of the intestinal microbiota. We also evaluated factors affecting the microbiota, during the first 3 months of life in preterm infants (n = 27) compared with full-term babies (n = 13).
Results Immaturity affects the microbiota as indicated by a reduced percentage of the family Bacteroidaceae during the first months of life and by a higher initial percentage of Lactobacillaceae in preterm infants compared with full term infants. Perinatal antibiotics, including intrapartum antimicrobial prophylaxis, affects the gut microbiota, as indicated by increased Enterobacteriaceae family organisms in the infants.

Human gut microbiome

Conclusions Prematurity and perinatal antibiotic administration strongly affect the initial establishment of microbiota with potential consequences for later health.

Ischemia and necrotizing enterocolitis: where, when, and how

Philip T. Nowicki
Seminars in Pediatric Surgery (2005) 14, 152-158
http://dx.doi.org:/10.1053/j.sempedsurg.2005.05.003

While it is accepted that ischemia contributes to the pathogenesis of necrotizing enterocolitis (NEC), three important questions regarding this role subsist. First, where within the intestinal circulation does the vascular pathophysiology occur? It is most likely that this event begins within the intramural microcirculation, particularly the small arteries that pierce the gut wall and the submucosal arteriolar plexus insofar as these represent the principal sites of resistance regulation in the gut. Mucosal damage might also disrupt the integrity or function of downstream villous arterioles leading to damage thereto; thereafter, noxious stimuli might ascend into the submucosal vessels via downstream venules and lymphatics. Second, when during the course of pathogenesis does ischemia occur? Ischemia is unlikely to the sole initiating factor of NEC; instead, it is more likely that ischemia is triggered by other events, such as inflammation at the mucosal surface. In this context, it is likely that ischemia plays a secondary, albeit critical role in disease extension. Third, how does the ischemia occur? Regulation of vascular resistance within newborn intestine is principally determined by a balance between the endothelial production of the vasoconstrictor peptide endothelin-1 (ET-1) and endothelial production of the vasodilator free radical nitric oxide (NO). Under normal conditions, the balance heavily favors NO-induced vasodilation, leading to a low resting resistance and high rate of flow. However, factors that disrupt endothelial cell function, eg, ischemia-reperfusion, sustained low-flow perfusion, or proinflammatory mediators, alter the ET-1:NO balance in favor of constriction. The unique ET-1–NO interaction thereafter might facilitate rapid extension of this constriction, generating a viscous cascade wherein ischemia rapidly extends into larger portions of the intestine.

Schematic representation of the intestinal microcirculation

Schematic representation of the intestinal microcirculation. Small mesenteric arteries pierce the muscularis layers and terminate in the submucosa where they give rise to 1A (1st order) arterioles. 2A (2nd order) arterioles arise from the 1A. Although not shown here, these 2A arterioles connect merge with several 1A arterioles, thus generating an arteriolar plexus, or manifold that serves to pressurize the terminal downstream microvasculature. 3A (3rd order) arterioles arise from the 2A and proceed to the mucosa, giving off a 4A branch just before descent into the mucosa. This 4A vessel travels to the muscularis layers. Each 3A vessel becomes the single arteriole perfusing each villus.

Collectively, these studies indicate that disruption of endothelial cell function has the potential to disrupt the normal balance between NO and ET-1 within the newborn intestinal circulation, and that such an event can generate significant ischemia. In this context, it is important to note that NO and ET-1 each regulate the expression and activity of the other. An increased [NO] within the microvascular environment reduces ET-1 expression and compromises ligand binding to the ETA receptor (thus decreasing its contractile efficacy), while ET-1 compromises eNOS expression. Thus, factors that upset the balance between NO and ET-1 will have an immediate and direct effect on vascular tone, but also exert an additional indirect effect by extenuating the disruption of balance between these two factors.

It is not difficult to construct a hypothesis that links the perturbations of I/R and sustained low-flow perfusion with an initial inflammatory insult. Initiation of an inflammatory process at the mucosal–luminal interface could have a direct impact on villus and mucosal 3A arterioles, damaging arteriolar integrity and disrupting villus hemodynamics. Ascent of proinflammatory mediators to the submucosal 1A–2A arteriolar plexus could occur via draining venules and lymphatics, generating damage to vascular effector systems therein; these mediators might include cytokines and platelet activating factor, as these elements have been recovered from human infants with NEC. This event, coupled with a generalized loss of 3A flow throughout a large portion of the mucosal surface, could compromise flow rate within the submucosal arteriolar plexus.

Necrotizing enterocolitis: An update

Loren Berman, R. Lawrence Moss
Seminars in Fetal & Neonatal Medicine 16 (2011) 145e150
http://dx.doi.org:/10.1016/j.siny.2011.02.002

Necrotizing enterocolitis (NEC) is a leading cause of death among patients in the neonatal intensive care unit, carrying a mortality rate of 15e30%. Its pathogenesis is multifactorial and involves an over reactive response of the immune system to an insult. This leads to increased intestinal permeability, bacterial translocation, and sepsis. There are many inflammatory mediators involved in this process, but thus far none has been shown to be a suitable target for preventive or therapeutic measures. NEC usually occurs in the second week of life after the initiation of enteral feeds, and the diagnosis is made based on physical examination findings, laboratory studies, and abdominal radiographs. Neonates with NEC are followed with serial abdominal examinations and radiographs, and may require surgery or primary peritoneal drainage for perforation or necrosis. Many survivors are plagued with long term complications including short bowel syndrome, abnormal growth, and neurodevelopmental delay. Several evidence-based strategies exist that may decrease the incidence of NEC including promotion of human breast milk feeding, careful feeding advancement, and prophylactic probiotic administration in at-risk patients. Prevention is likely to have the greatest impact on decreasing mortality and morbidity related to NEC, as little progress has been made with regard to improving outcomes for neonates once the disease process is underway.

Immune Deficiencies

Primary immunodeficiencies: A rapidly evolving story

Nima Parvaneh, Jean-Laurent Casanova, LD Notarangelo, ME Conley
J Allergy Clin Immunol 2013;131:314-23.
http://dx.doi.org/10.1016/j.jaci.2012.11.051

The characterization of primary immunodeficiencies (PIDs) in human subjects is crucial for a better understanding of the biology of the immune response. New achievements in this field have been possible in light of collaborative studies; attention paid to new phenotypes, infectious and otherwise; improved immunologic techniques; and use of exome sequencing technology. The International Union of Immunological Societies Expert Committee on PIDs recently reported on the updated classification of PIDs. However, new PIDs are being discovered at an ever-increasing rate. A series of 19 novel primary defects of immunity that have been discovered after release of the International Union of Immunological Societies report are discussed here. These new findings highlight the molecular pathways that are associated with clinical phenotypes and suggest potential therapies for affected patients.

Combined Immunodeficiencies

T-cell receptor a gene mutation: T-cell receptor ab1 T-cell depletion

T cells comprise 2 distinct lineages that express either ab or gd T-cell receptor (TCR) complexes that perform different tasks in immune responses. During T-cell maturation, the precise order and efficacy of TCR gene rearrangements determine the fate of the cells. Productive β-chain gene rearrangement produces a pre-TCR on the cell surface in association with pre-Tα invariant peptide (β-selection). Pre-TCR signals promote α-chain recombination and transition to a double-positive stage (CD41CD81). This is the prerequisite for central tolerance achieved through positive and negative selection of thymocytes.

Ras homolog gene family member H deficiency: Loss of naive T cells and persistent human papilloma virus infections
MST1 deficiency: Loss of naive T cells

New insight into the role of MST1 as a critical regulator of T-cell homing and function was provided by the characterization of 8 patients from 4 unrelated families who had homozygous nonsense mutations in STK4, the gene encoding MST1. MST1 was originally identified as an ubiquitously expressed kinase with structural homology to yeast Ste. MST1 is the mammalian homolog of the Drosophila Hippo protein, controlling cell growth, apoptosis, and tumorigenesis. It has both proapoptotic and antiapoptotic functions.

Lymphocyte-specific protein tyrosine kinase deficiency: T-cell deficiency with CD41 lymphopenia

Defects in pre-TCR– and TCR-mediated signaling lead to aberrant T-cell development and function (Fig). One of the earliest biochemical events occurring after engagement of the (pre)-TCR is the activation of lymphocyte-specific protein tyrosine kinase (LCK), a member of the SRC family of protein tyrosine kinases. This kinase then phosphorylates immunoreceptor tyrosine-based activation motifs of intracellular domains of CD3 subunits. Phosphorylated immunoreceptor tyrosine-based activation motifs recruit z-chain associated protein kinase of 70 kDa, which, after being phosphorylated by LCK, is responsible for activation of critical downstream events. Major consequences include activation of the membrane-associated enzyme phospholipase Cg1, activation of the mitogen-activated protein kinase, nuclear translocation of nuclear factor kB (NFkB), and Ca21/Mg21 mobilization. Through these pathways, LCK controls T-cell development and activation. In mice lacking LCK, T-cell development in the thymus is profoundly blocked at an early double-negative stage.

TCR signaling

TCR signaling. Multiple signal transduction pathways are stimulated through the TCR. These pathways collectively activate transcription factors that organize T-cell survival, proliferation, differentiation, homeostasis, and migration. Mutant molecules in patients with TCR-related defects are indicated in red.

Uncoordinated 119 deficiency: Idiopathic CD41 lymphopenia

Idiopathic CD41 lymphopenia (ICL) is a very heterogeneous clinical entity that is defined, by default, by persistent CD41 T-cell lymphopenia (<300 cells/mL or <20% of total T cells) in the absence of HIV infection or any other known cause of immunodeficiency.

Well-Defined Syndromes with Immunodeficiency

Wiskott-Aldrich syndrome protein–interacting protein deficiency: Wiskott-Aldrich syndrome-like phenotype

In hematopoietic cells Wiskott-Aldrich syndrome protein (WASP) is stabilized through forming a complex with WASP interacting protein (WIP).

Phospholipase Cg2 gain-of-function mutations: Cold urticaria, immunodeficiency, and autoimmunity/autoinflammatory

This is a unique phenotype, sharing features of antibody deficiency, autoinflammatory diseases, and immune dysregulatory disorders, making its classification difficult. Two recent studies validated the pleiotropy of genetic alterations in the same gene.

Predominantly Antibody Defects

Defect in the p85a subunit of phosphoinositide 3-kinase: Agammaglobulinemia and absent B cells
CD21 deficiency: Hypogammaglobulinemia
LPS-responsive beige-like anchor deficiency:
Hypogammaglobulinemia with autoimmunity and

early colitis

Defects Of Immune Dysregulation

Pallidin deficiency: Hermansky-Pudlak syndrome type 9
CD27 deficiency: Immune dysregulation and
persistent EBV infection

Congenital Defects Of Phagocyte Number, Function, Or Both

Interferon-stimulated gene 15 deficiency: Mendelian susceptibility to mycobacterial diseases

Defects In Innate Immunity

NKX2-5 deficiency: Isolated congenital asplenia
Toll/IL-1 receptor domain–containing adaptor inducing IFN-b and TANK-binding kinase 1 deficiencies: Herpes simplex encephalitis
Minichromosome maintenance complex component 4 deficiency: NK cell deficiency associated with growth retardation and adrenal insufficiency

Autoinflammatory Disorders

A disintegrin and metalloproteinase 17 deficiency: Inflammatory skin and bowel disease

Cross-talk between monocyte.macrophage cells and T.NK lymphocytes

Cross-talk between monocyte/macrophage cells and T/NK lymphocytes. Genes in the IL-12/IFN-g pathway are particularly important for protection against mycobacterial disease. IRF8 is an IFN-g–inducible transcription factor required for the induction of various target genes, including IL-12. The NF-kB essential modulator (NEMO) mutations in the LZ domain impair CD40-NEMO–dependent pathways. Some gp91phox mutations specifically abolish the respiratory burst in monocyte-derived macrophages. ISG15 is secreted by neutrophils and potentiates IFN-g production by NK/T cells. Genetic defects that preclude monocyte development (eg, GATA2) can also predispose to mycobacterial infections (not shown). Mutant molecules in patients with unusual susceptibility to infection are indicated in red.

The field of PIDs is advancing at full speed in 2 directions. New genetic causes of known PIDs are being discovered (eg, CD21 and TRIF). Moreover, new phenotypes qualify as PIDs with the identification of a first genetic cause (eg, generalized pustular psoriasis). Recent findings contribute fundamental knowledge about immune system biology and its perturbation in disease. They are also of considerable clinical benefit for the patients and their families. A priority is to further translate these new discoveries into improved diagnostic methods and more effective therapeutic strategies, promoting the well-being of patients with PIDs.

Primary immunodeficiencies

Luigi D. Notarangelo
J Allergy Clin Immunol 2010; 125(2): S182-194
http://dx.doi.org:/10.1016/j.jaci.2009.07.053

In the last years, advances in molecular genetics and immunology have resulted in the identification of a growing number of genes causing primary immunodeficiencies (PIDs) in human subjects and a better understanding of the pathophysiology of these disorders. Characterization of the molecular mechanisms of PIDs has also facilitated the development of novel diagnostic assays based on analysis of the expression of the protein encoded by the PID-specific gene. Pilot newborn screening programs for the identification of infants with severe combined immunodeficiency have been initiated. Finally, significant advances have been made in the treatment of PIDs based on the use of subcutaneous immunoglobulins, hematopoietic cell transplantation from unrelated donors and cord blood, and gene therapy. In this review we will discuss the pathogenesis, diagnosis, and treatment of PIDs, with special attention to recent advances in the field.

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Graft-versus-Host Disease

Posted in Acute lymphocytic leukemia, Acute myelocytic leukemia, Bone marrow derived cells, Cell Biology, Curation, Hematology, Hematopoiesis, Human Immune System in Health and in Disease, Immuno-Oncology & Genomics, Innovation in Immunology Diagnostics, Molecular Genetics & Pharmaceutical, Mutant Gene Expression, Pharmaceutical Analytics, Pharmaceutical Drug Discovery, Pharmacologic toxicities, Regenerative Biology and Medicine, Signaling & Cell Circuits, Stem Cells for Regenerative Medicine, Translational Science, Umbilical cord cells, tagged Acute myeloid leukemia, aGVHD, allogeneic hemopoietic transplant, bone-marrow transplant, cGVHD, chimerism, dermatologic complications, graft-versus-host disease, pretransplant conditioning, Progenitor cell, pulmonary sclerosis, stem cells, T cells, thalassemia, umbilical cord stem cells on February 19, 2015| Leave a Comment »

Graft-versus-Host Disease

Writer and Curator: Larry H. Bernstein, MD, FCAP

Introduction

This piece is a follow up to the article on allogeneic transfusion reactions, which extends into transplantation and transplantation outcomes for hematological diseases, both malignant and nonmalignant. The safety of transfusions in Western countries has improved substantially, and the causes for transfusion mishaps has been reduced to unexpected infectious sources, uncommon immune incompatibilities, and errors in processing the blood products. The greatest risk is incurred in platelet transfusions because of the short shelf-life of the product, and the time needed for testing prior to release. This portion of the review is concerned with Graft-versus-Host Disease, which is unique to transfusion and transplanting of blood. In other transplantation, there is graft failure because of host versus graft incompatibility or complications. The reverse order applies to blood. In this case, on the contrary, the transfused or grafted donor tissue becomes a pursuer after the recipients hematopoietic cells.

Peter Brian Medawar: Father of Transplantation

Thomas E. Starzl, M.D., PH.D., F.A.C.S.
J Am Coll Surg. 1995 Mar; 180(3): 332–336

Most of the surgical specialities can be tracked to the creative vision of a surgeon. Transplantation is an exception. Here, the father of the field is succinctly defined in the dictionary as: “Peter Brian Medawar: a Brazilian born British Zoologist who at the age of 45 shared a 1960 Nobel Prize for his work on acquired immunologic tolerance”. Medawar was mysteriously overwhelming to many colleagues and observers, even when he was young. He was the son of a Lebanese father and an English mother—tall, athletic, abnormally handsome, hypnotically articulate in public, and politely cordial in his personal relations. In September 1969, at the age of 54, he had the first of a series of strokes. These crippled him physically but not in spirit. Although I saw Medawar often professionally and privately over a 22 year period, before and after he was disabled, this sporadic exposure was not enough to understand him. My sense is that no one did, except perhaps Jean, his wife for nearly 50 years.

Medawar’s dazzling personality before and great courage after his strokes was inspirational, but his fame was based on the unique achievement in 1953 captured by the terse dictionary mention of “acquired immunologic tolerance.” The roots leading to this accomplishment had fed on the blood of war. More than 12 years earlier, the recently wed zoologist Medawar—24 years of age and fresh from graduate studies at Oxford University—was assigned to
the service of the British surgeon, Dr. Thomas Gibson, to determine if skin allografts could be used to treat casualties from the Battle of Britain. First,
in human studies with Gibson, and then with simple and logical rabbit experiments, Medawar showed that rejection of the skin was an immunologic phenomenon. This later was shown to be analogous to the cell-mediated delayed hypersensitivity that confers immunity to diseases such as tuberculosis. The principal evidence in the early studies was that repetitive grafts from the same donor were rejected more rapidly with each successive attempt —the sensitization and donor specificity confirming an earlier clinical observations by Emil Holman of Stanford in skin-grafted burn victims. Once it was established that rejection was an immune reaction, strategies began to evolve to weaken the recipient immune system. By 1953, total body irradiation and adrenal cortical steroids had been shown to delay skin rejection. However, this immunosuppressive effect was either minor if the animals survived, or lethal to the recipient if the grafts were spared.

Bombshell

In the resulting atmosphere of nihilism about clinical applications, a three and one-half page article by Billingham, Brent, and Medawar in the October 3, 1953 issue of Nature describing acquired tolerance, came as a blinding beacon of hope. The three men had learned that donor splenocytes could be engrafted by their intravenous infusion into immunologically immature mice in utero or perinatally. When these inoculated recipients matured, they could accept skin and other tissues from the donor (but from no other) mouse strain. The immune system of the recipients had been populated by the immunocytes of the donor, meaning that they were now chimeras. The race was on to convert this principle to humans. However, the dark side of their accomplishment soon was revealed by the two younger members of Medawar’s team, Billingham and Brent and by the Dane, Simonsen. The engrafted donor cells could turn the tables and reject the defenseless recipient unless the tissue match was a good one. This was the dreaded graft versus host disease (GVHD) in which transplanted donor cells attacked the recipient skin, gastrointestinal tract, lungs, liver, and the bone marrow itself. Medawar’s dream of 1953 was suddenly a nightmare. Or was it?

On the contrary, the work took a straight line to clinical application, after the demonstration by Prehn and Main that similar tolerance could be induced in adult mice rendered immunologically defenseless by total body irradiation before splenocyte (or later bone marrow) infusion. The recipient conditioning, known as cytoablation, also could be accomplished with myelotoxic drugs. However, as Billingham, Brent, and Medawar had predicted, donor specific tolerance could be induced in humans without GVHD only if there was a good tissue (HLA) match. In 1968, 15 years after the epic Billingham, Brent and Medawar publication, Robert Good and Fritz Bach reported the first two successful human bone marrow transplants. Both recipients of well matched bone marrow from blood relatives are still alive. This was a triumph in which the principal clinicians were internists, as summarized 25 years later in the acceptance speech by the 1990 Nobel Laureate Donnall Thomas.

The growth of bone marrow and whole organ transplantation

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2681237/bin/nihms-87975-f0001.gif

The growth of bone marrow (right) and whole organ transplantation (left) from the seed planted by Peter Medawar during World War II. GVHD, Graft versus host disease.

Immunological Tolerance: Medawar Nobel Acceptance Lecture

“Immunological tolerance” may be described as a state of indifference or non-reactivity towards a substance that would normally be expected to excite an immunological response. The term first came to be used in the context of tissue transplantation immunity, i.e. of the form of immunity that usually prohibits the grafting of tissues between individuals of different genetic make-up; and it was used to refer only to a non-reactivity caused by exposing animals to antigenic stimuli before they were old enough to undertake an immunological response. For example, if living cells from a mouse of strain CBA are injected into an adult mouse of strain A, the CBA cells will be destroyed by an immunological process, and the A-line mouse that received them will destroy any later graft of the same origin with the speed to be expected of an animal immunologically forearmed. But if the CBA cells are injected into a foetal or newborn A-line mouse, they are accepted; more than that, the A-line mouse, when it grows up, will accept any later graft from a CBA donor as if it were its own. I shall begin by using the term “immunological tolerance” in the rather restricted sense that is illustrated by this experiment, and shall discuss its more general usage later on.

The experiment I have just described can be thought of as an artificial reproduction of an astonishing natural curiosity, the phenomenon of red-cell chimerism in certain dizygotic twins. The blood systems of twin cattle before birth are not sharply distinct from each other, as they are in most other twins; instead, the blood systems make anastomoses with each other, with the effect that the twins can indulge in a prolonged exchange of blood before birth. In 1945, R.D. Owen2 made the remarkable discovery that most twin cattle are born with, and may retain throughout life, a stable mixture – not necessarily a fifty-fifty mixture – of each other’s red cells; it followed, then, that the twin cattle must have exchanged red-cell precursors and not merely red cells in their mutual transfusion before birth. This is the first example of the phenomenon we came to call immunological tolerance; the red cells could not have “adapted” themselves to their strange environment, because they were in fact identified as native or foreign by those very antigenie properties which, had an adaptation occurred, must necessarily have been transformed. A few years later R.E. Billingham and I3, with the help of three members of the scientific staff of the Agricultural Research Council, showed that most dizygotic cattle twins would accept skin grafts from each other, and that this mutual tolerance was specific, for skin transplanted from third parties was cast off in the expected fashion.

Some properties of the tolerant state

The main points that emerged from our analysis of the tolerant state were these. In the first place, tolerance must be due to an alteration of the host, not to an antigenic adaptation of the grafted cells, for grafts newly transplanted in adult life have no opportunity to adapt themselves, and the descendants of the cells injected into foetal or newborn animals can be shown by N.A. Mitcbison’s methods to retain their antigenic power10. Once established, the state of tolerance is systemic; if one part of the body will tolerate a foreign graft, so will another; we found no evidence that a tolerated graft builds up a privileged position for itself within its own lymphatic territory. The stimulus that is responsible for instating tolerance is an antigenic stimulus – one which, had it been applied to older animals, would have caused them to become sensitive or immune. A plural stimulus can induce plural tolerance; the donor will usually contain several important antigens that are lacking in the recipient, and long-lasting tolerance must imply tolerance of them all. The state of tolerance is specific in the sense that it will discriminate between one individual and another, for an animal made tolerant of grafts from one individual will not accept grafts from a second individual unrelated to the first; but it will not discriminate between one tissue and another from the same donor.

Tolerance and auto-immunity: 50 years after Burnet.

Martini A1, Burgio GR
Eur J Pediatr. 1999 Oct;158(10):769-75.

Fifty years ago Sir F. Macfarlane Burnet published his first fundamental contribution to the theory of immune tolerance he perfected 10 years later. Since then an impressive amount of new information on the function of the immune system has been gathered. As any original meaningful theory, Burnet’s hypothesis on the development of immune tolerance has undergone extensive modifications to take into account all these new findings. An improved understanding of the mechanisms of tolerance has led to new possibilities for the treatment of auto-immune diseases.

Clonal Selection
http://en.wikipedia.org/wiki/Clonal_selection

Clonal selection theory is a scientific theory in immunology that explains the functions of cells (lymphocytes) of the immune system in response to specific antigens invading the body. The concept was introduced by an Australian doctor Frank Macfarlane Burnet in 1957 in an attempt to explain the formation of a diversity of antibodies during initiation of the immune response. The theory has become a widely accepted model for how the immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens.

The theory states that in a pre-existing group of lymphocytes (specifically B cells), a specific antigen only activates (i.e. selection) its counter-specific cell so that particular cell is induced to multiply (producing its clones) for antibody production. In short the theory is an explanation of the mechanism for the generation of diversity of antibody specificity. The first experimental evidence came in 1958, when Gustav Nossal and Joshua Lederberg showed that one B cell always produces only one antibody. The idea turned out to be the foundation of molecular immunology, especially in adaptive immunity.

The fundamental contribution of Robert A. Good to the discovery of the crucial role of thymus in mammalian immunity

Domenico Ribatti
Immunology. 2006 Nov; 119(3): 291–295.
http://dx.doi.org:/10.1111/j.1365-2567.2006.02484.x

Robert Alan Good was a pioneer in the field of immunodeficiency diseases. He and his colleagues defined the cellular basis and functional consequences of many of the inherited immunodeficiency diseases. His was one of the groups that discovered the pivotal role of the thymus in the immune system development and defined the separate development of the thymus-dependent and bursa-dependent lymphoid cell lineages and their responsibilities in cell-mediated and humoral immunity. Keywords: bursa of Fabricius, history of medicine, immunology, thymus

Robert Alan Good (May 21, 1922 – June 13, 2003) was an American physician who performed the first successful human bone marrow transplant

Robert A. Good began his intellectual and experimental queries related to the thymus in 1952 at the University of Minnesota, initially with pediatric patients. However, his interest in the plasma cell, antibodies and the immune response began in 1944, while still in Medical School at the University of Minnesota in Minneapolis, with his first publication appearing in 1945.

Idiopathic Acquired Agammaglobulinemia Associated with Thymoma (1953)

a markedly deficient ability to produce antibodies and significant deficits of all or most of the cell-mediated immunities
in no instance did removal of the thymic tumour restore immunological function or correct the protein deficit

Good syndrome: thymoma with immunodeficiency

increased susceptibility to bacterial infections by encapsulated organisms and opportunistic viral and fungal infections
immunodeficiencies, leukopenia, lymphopenia and eosinophylopenia
severely hypogammaglobulinemic rather than agammaglobulinemic

Good and others found that the patients lacked all of the subsequently described immunoglobulins. These patients were found not to have plasma cells or germinal centers in their hematopoietic and lymphoid tissues. They possessed circulating lymphocytes in normal numbers.

Speculation on the reason for immunological failure following neonatal thymectomy has centered on the thymus as a source of cells or humoral factors essential to normal lymphoid development and immunological maturation.

The bursa of Fabricius and the thymus are ‘central lymphoid organs’ in the chicken, essential to the ontogenetic development of adaptive immunity in that species. Studies by Papermaster and co-workers in Good’s laboratory34,35 indicated that bursectomy in the newly hatched chicks did not completely abolish immunological potential in the adult animal but rather produced a striking quantitative reduction insufficient to eliminate the homograft reaction. The failure of thymectomy in newly hatched chicks to alter the immunological potential of the maturing animal probably only reflected the participation of the bursa of Fabricius in the development of full immunological capacity.

Bursectomized and irradiated birds were completely devoid of germinal centers, plasma cells and the capacity to make antibodies yet they had perfectly normal development of thymocytes and lymphocytes elsewhere in the body that mediated cellular immune reactions. On the other hand, thymectomized and irradiated animals were deficient in lymphocytes that mediated cellular immunity as assessed by skin graft rejection, delayed-type hypersensitivity and graft versus host assays, but they still produced germinal centers, plasma cells and circulating immunoglobulins.

Graft vs Host Disease

Graft-versus-host disease (GVHD) is a complication that can occur after a stem cell or bone marrow transplant. With GVHD, the newly transplanted donor cells attack the transplant recipient’s body.

Graft-versus-host disease (GVHD) is a common complication following an allogeneic tissue transplant. It is commonly associated with stem cell or bone marrow transplant but the term also applies to other forms of tissue graft. Immune cells (white blood cells) in the tissue (the graft) recognize the recipient (the host) as “foreign“. The transplanted immune cells then attack the host’s body cells. GVHD can also occur after a blood transfusion if the blood products used have not been irradiated or treated with an approved pathogen reduction system.

http://en.wikipedia.org/wiki/Graft-versus-host_disease

Causes

GVHD may occur after a bone marrow or stem cell transplant in which someone receives bone marrow tissue or cells from a donor. This type of transplant is called allogeneic. The new, transplanted cells regard the recipient’s body as foreign. When this happens, the newly transplanted cells attack the recipient’s body.

GVHD does not occur when someone receives his or her own cells during a transplant. This type of transplant is called autologous.

Before a transplant, tissue and cells from possible donors are checked to see how closely they match the person having the transplant. GVHD is less likely to occur, or symptoms will be milder, when the match is close. The chance of GVHD is:

Around 30 – 40% when the donor and recipient are related
Around 60 – 80% when the donor and recipient are not related

There are two types of GVHD: acute and chronic. Symptoms in both acute and chronic GVHD range from mild to severe.

Acute GVHD usually happens within the first 6 months after a transplant.
Chronic GVHD usually starts more than 3 months after a transplant, and can last a lifetime.

Bone marrow transplant

A bone marrow transplant is a procedure to replace damaged or destroyed bone marrow with healthy bone marrow stem cells. Stem cells are immature cells in the bone marrow that give rise to all of your blood cells.

There are three kinds of bone marrow transplants:

Autologous bone marrow transplant: The term auto means self. Stem cells are removed from you before you receive high-dose chemotherapy or radiation treatment. The stem cells are stored in a freezer (cryopreservation). After high-dose chemotherapy or radiation treatments, your stems cells are put back in your body to make (regenerate) normal blood cells. This is called a rescue transplant.
Allogeneic bone marrow transplant: The term allo means other. Stem cells are removed from another person, called a donor. Most times, the donor’s genes must at least partly match your genes. Special blood tests are done to see if a donor is a good match for you. A brother or sister is most likely to be a good match. Sometimes parents, children, and other relatives are good matches. Donors who are not related to you may be found through national bone marrow registries.
Umbilical cord blood transplant: This is a type of allogeneic transplant. Stem cells are removed from a newborn baby’s umbilical cord right after birth. The stem cells are frozen and stored until they are needed for a transplant. Umbilical cord blood cells are very immature so there is less of a need for matching. But blood counts take much longer to recover.

Before the transplant, chemotherapy, radiation, or both may be given. This may be done in two ways:

Ablative (myeloablative) treatment: High-dose chemotherapy, radiation, or both are given to kill any cancer cells. This also kills all healthy bone marrow that remains, and allows new stem cells to grow in the bone marrow.
Reduced intensity treatment, also called a mini transplant: Patients receive lower doses of chemotherapy and radiation before a transplant. This allows older patients, and those with other health problems to have a transplant.

Histocompatibility antigen:

A histocompatibility antigen blood test looks at proteins called human leukocyte antigens (HLAs). These are found on the surface of almost all cells in the human body. HLAs are found in large amounts on the surface of white blood cells. They help the immune system tell the difference between body tissue and substances that are not from your own body.

http://www.nlm.nih.gov/medlineplus/ency/article/001309.htm

Induction of transplantation tolerance in haploidenical transplantation under reduced intensity conditioning: The role of ex-vivo generated donor CD8⁺ T cells with central memory phenotype

Eran Ophir, Y Eidelstein, E Bachar-Lustig, D Hagin, N Or-Geva, A Lask, , Y Reisner
Best Practice & Research Clinical Haematology 24 (2011) 393–401
http://dx.doi.org:/10.1016/j.beha.2011.05.007

Haploidentical hematopoietic stem cell transplantation (HSCT) offers the advantage of readily available family member donors for nearly all patients. A ‘megadose’ of purified CD34þ hematopoietic stem cells is used to overcome the host’s residual immunity surviving the myeloablative conditioning, while avoiding severe GVHD. However, the number of CD34⁺ cells that can be harvested is insufficient for overcoming the large numbers of host T cells remaining after reduced intensity conditioning (RIC). Therefore, combining a ‘megadose’ of CD34⁺ HSCT with other tolerizing cells could potentially support and promote successful engraftment of haploidentical purified stem cell transplantation under a safer RIC. One approach to address this challenge
could be afforded by using Donor CD8 T cells directed against 3rd-party stimulators, bearing an ex-vivo induced central memory phenotype (Tcm). These Tcm cells, depleted of GVH reactivity, were shown to be highly
efficient in overcoming host T cells mediated rejection and in promoting
fully mismatched bone-marrow (BM) engraftment, in HSCT murine models.
This is likely due to the marked lymph node homing of the Tcm, their strong proliferative capacity and prolonged persistence in BM transplant recipients. Thus, combining anti 3rd-party Tcm cell therapy with a ‘megadose’ of purified CD34⁺stem cells, could offer a safer RIC protocol for attaining hematopoietic chimerism in patients with hematological diseases and as a platform for organ transplantation or cell therapy in cancer patients.

Induction of tolerance in organ recipients by hematopoietic stem cell transplantation

Eran Ophir, Yair Reisner
International Immunopharmacology 9 (2009) 694–700
http://dx.doi.org:/10.1016/j.intimp.2008.12.009

The use of hematopoietic stem cell transplantation (HSCT) for the establishment of mixed chimerism represents a viable and attractive approach for generating tolerance in transplantation biology, as it generally leads to durable immune tolerance, enabling the subsequent engraftment of organ transplants without the need for a deleterious continuous immunosuppressive therapy. However, in order to apply HSCT to patients in a manner that enables long term survival, transplant-related mortality must be minimized by eliminating the risk for graft-versus-host-disease (GVHD) and by reducing the toxicity of the conditioning protocol. T-cell depleted bone marrow transplants (TDBMT) have been shown to adequately eliminate GVHD. However, even in leukemia patients undergoing supralethal conditioning, mismatched TDBMT are vigorously rejected. This barrier can be overcome through the modulatory activity of CD34 cells, which are endowed with veto activity, by the use of megadose stem cell transplants. In mice, megadoses of Sca⁺lin^–hematopoietic stem cells can induce mixed chimerism following sub-lethal conditioning. Nevertheless, the number of human CD34 cells that can be harvested is not likely to be sufficient to overcome rejection under reduced intensity conditioning (RIC), which might be acceptable in recipients of organ transplantation. To address this challenge, we investigated a novel source of veto cells, namely anti 3rd-party cytotoxic T cells (CTLs) which are depleted of GVH reactivity, combined with megadoses of purified stem cells and a RIC protocol. This approach might provide a safer modality for the induction of durable chimerism.

Intrinsic unresponsiveness of Mertk/B cells to chronic graft-versus-host disease is associated with unmodulated CD1d expression

Wen-Hai Shao, Y Zhen, FD Finkelman, RA Eisenberg, PL Cohen
Journal of Autoimmunity 39 (2012) 412e419
http://dx.doi.org/10.1016/j.jaut.2012.07.001

Activation and migration of marginal zone B (MZB) cells into follicular (FO) regions of the spleen has been proposed as one of the mechanisms that regulate the development of autoreactive B cells. The mer receptor tyrosine kinase (Mertk) mediates apoptotic cell clearance and regulates activation and cytokine secretion. In the well-studied class II chronic GVH model of bm12 cells into B6 hosts, we observed that Mertk deficient B6 mice did not generate autoantibodies in response to this allogeneic stimulus. We posited that Mertk is important in MHC-II-mediated B cell signaling. In the present study, we show that B cells from Mertk^-/- mice but not WT B6 mice exhibited decreased calcium mobilization and tyrosine phosphorylation when stimulated by MHC-II cross-linking. The finding that Mertk was important for class II signaling in B cells was further supported by the preponderance of a-allotype autoantibodies in cGVH in RAG-KO mice reconstituted with a mixture of bone marrow from Mertk^-/-mice (b-allotype) and C20 mice (a-allotype). MZB cells from Mertk^-/- mice were unable to down regulate surface CD1d expression and subsequent inclusion in the MZ, associated with significantly lower germinal center responses compared to MZB cells from WT. Moreover, Mertk^-/-mice treated with an anti-CD1d down regulating antibody responded significantly to bm12 cells, while no response was observed in Mertk^-/- mice treated with control antibodies. Taken together, these findings extend the role of Mertk to include CD1d down regulation on MZB cells, a potential mechanism limiting B cell activation in cGVH.

Galectin-9 ameliorates acute GVH disease through the induction of T-cell apoptosis

Kazuki Sakai, Eri Kawata, Eishi Ashihara, Yoko Nakagawa, et al.
Eur. J. Immunol. 2011. 41: 67–75 http://dx.doi.org:/10.1002/eji.200939931

Galectins comprise a family of animal lectins that differ in their affinity for β-galactosides. Galectin-9 (Gal-9) is a tandem-repeat-type galectin that was recently shown to function as a ligand for T-cell immunoglobin domain and mucin domain-3 (Tim-3) expressed on terminally differentiated CD41 Th1 cells. Gal-9 modulates immune reactions, including the induction of apoptosis in Th1 cells. In this study, we investigated the effects of Gal-9 in murine models of acute GVH disease (aGVHD). First, we demonstrated that recombinant human Gal-9 inhibit MLR in a dose-dependent manner, involving both Ca21 influx and apoptosis in T cells. Next, we revealed that recombinant human Gal-9 significantly inhibit the progression of aGVHD in murine BM transplantation models. In conclusion, Gal-9 ameliorates aGVHD, possibly by inducing T-cell apoptosis, suggesting that gal-9 may be an attractive candidate for the treatment of aGVHD.

GVHD Prevention: An Ounce Is Better Than a Pound

Pavan Reddy, Gerard Socie, Corey Cutler, Daniel Weisdorf
Biol Blood Marrow Transplant 18:S17-S26, 2012 http://dx.doi.org:/10.1016/j.bbmt.2011.10.034

The pathophysiology of acute graft-versus-host disease (aGVHD) is known to involve donor T cells responding to host histoincompatible allo-antigens presented by the host antigen presenting cells (APCs) and the subsequent induction of pro-inflammatory cytokines and cellular effectors that cause target organ damage. In a more general sense, GVHD can be considered as an immune response against foreign antigens that has gone awry. Similar to all immune responses, GVHD, can be understood as a process that consists of (A) triggers, (B) sensors, (C) mediators, and (D) effectors of GVHD.

Like all immune responses, certain triggers are critical for induction of acute graft-versus-host disease (aGVHD). These include: (1) Disparities between histocompatibility antigens: antigen disparity can be at the level of major histocompatibility complex (MHC), that is, MHC mismatched or at the level of minor histocompatibility antigens (miHA), that is, MHC matched but miHA mismatched. The severity of aGVHD is directly related to the degree of M HC mismatch. In bone marrow transplants (BMT) that are MHC matched but miHA disparate, donor T cells still recognize MHC-peptide derived from the products of recipient polymorphic genes, the miHAs.

Damage induced by conditioning regimens and underlying diseases: under most circumstances, the initiation of an adaptive immune response is triggered by the innate immune response. The innate immune system is triggered by certain exogenous and endogenous molecules. This is likely the case in the induction of aGVHD. Pattern recognition receptors such as Toll-like receptors (TLR), nucleotide-binding oligomerization domain containing 2 (NOD2) play an essential role in innate immunity and in initiating the cellular signaling pathways that activate cytokine secretion, such as NF-kB. Some of their ligands, such as lipopolysaccharide, CpG, and MDP2, which is recognized by TLR-4, TLR-9, and NOD2, respectively, are released by the preparative regimens and contribute to the induction and enhancement of allo-T cell responses. In this way, the conditioning regimens amplify the secretion of proinflammatory cytokines like interleukin (IL)-1, tumor necrosis factor (TNF)-α, IL-6, and other interferon family members in a process described as a ‘‘cytokine storm.’’

The triggers that initiate an immune response have to be sensed and presented. APCs might be considered the sensors for aGVHD. The APCs sense the DAMPs, present the MHC disparate or miHA disparate protein, and provide the critical secondary (costimulatory) and tertiary (cytokine) signals for activation of the alloreactive T cells, the mediators of aGVHD. APCs sense allo-disparity through MHC and peptide complexes. Dendritic cells (DCs) are the most potent APCs and the primary sensors of allo-disparity.

APCs provide the critical costimulation signals for turning on the aGVHD process. The interaction between the MHC/allopeptide complex on APCs and the T cell receptor of donor T cells along with the signal via T cell costimulatory molecules and their ligands on APCs is required to achieve T cell activation, proliferation, differentiation, and survival and the in vivo blockade of positive costimulatory molecules (such as CD28, ICOS, CD40, CD30, etc.), or inhibitory signals (such as PD-1 and CTLA-4) mitigate or exacerbate aGVHD, respectively.

Evidence suggests that alloreactive donor T cells consist of several subsets with different stimuli responsiveness, activation thresholds, and effector functions.

The allo-antigen composition of the host determines which donor T cells subsets differentiate and proliferate. As mentioned previously, in the majority of HLA-matched HCT, aGVHD may be induced by either or both CD41 and CD81 subsets responses to miHAs. The repertoire and immunodominance of the GVHD-associated peptides presented by MHC class I and class II molecules has not been defined. Donor naive CD62L1 T cells are the primary alloreactive T cells that drive the GVHD reaction while the donor effector memory CD62L2 T cells do not. Interestingly, donor regulatory T cells (Tregs) expressing CD62L are also critical to the regulation of GVHD. We now know that it is possible to modulate the alloreactivity of na€ıve T cells by inducing anergy with costimulation blockade, deletion via cytokine modulation, or mixed chimerism. Donor effector memory T cells that are nonalloreactive do not induce GVHD, yet are able to transfer functional memory. In contrast, memory T cells that are alloreactive can cause severe GVHD.

The effector phase that leads to GVHD target organ damage is a complex cascade that involves cytolytic cellular effectors such as CD8 cytotoxic T lymphocytes (CTLs), CD4 T cells, natural killer cells, and inflammatory molecules such as IL-1β, TNF-α, IFN-ϒ, IL-6, and reactive oxygen species. The cellular effectors require cell-cell contact to kill the cells of the target tissues via activation of perforin granzyme, Fas-FasL (CD95-CD95L), or TNFR TRAIL pathways. Other CTLs killing mechanisms such as TWEAK, and LTβ/LIGHT pathways have also been implicated in GVHD. It is important to note that
CTL pathways are essential for GVL effects as well.

All of the above aspects of the biology of aGVHD have been summarized in the mold of a normal immune response. Although this allows for accessing the biology of GVHD, it is important to note that GVHD is a complicated systemic process with as yet still many unknowns and is not a simplified, linear, or cyclical process.

Kinetics of CD4⁺ and CD8⁺T-cell subsets in graft-versus-host reaction (GVHR) in ginbuna crucian carp Carassius auratus langsdorfii

Yasuhiro Shibasakia, H Todaa, Isao kobayashib, T Moritomoa, T Nakanishia
Developmental and Comparative Immunology 34 (2010) 1075–1081
http://dx.doi.org:/10.1016/j.dci.2010.05.009

We have previously demonstrated the presence of graft-versus-host reaction (GVHR) in fish employing a model system of clonal triploid ginbuna and tetraploid ginbuna-goldfish hybrids. To elucidate the role of CD8⁺ T cells in the induction of GVHR, we investigate the kinetics of CD4⁺ and CD8⁺T-cell subsets in GVHR along with the pathological changes associated with GVH disease (GVHD) in ginbuna. GVHR was not induced with a leukocyte fraction lacking CD8⁺ T cells separated by magnetic cell sorting. Ploidy and immunofluorescence analysis revealed that CD4⁺ and CD8+ T cells from sensitized donors greatly

increased in the host trunk kidney, constituting more than 80% of total cells 1–2 weeks after donor cell injection, while those from non-sensitized donors constituted less than 50% of cells present. The increase of CD4+ T cells was greater and more rapid than that of CD8⁺ T cells. The number of donor CD4⁺ and CD8⁺ T cells was highest in trunk kidney followed by spleen. Increases in donor CD4⁺ and CD8+ T cells were also found in liver and PBL, although the percentages were not as high. Pathologic changes similar to those in human and murine acute GVHD were observed in the lymphoid organs as well as target organs such as skin, liver and intestine, including the destruction of cells and tissues and massive leukocyte infiltration. The pathologic changes became more severe with the increase of CD8⁺ T cells. These results suggest that donor-derived CD8⁺ T cells play essential roles for the induction of acute GVHR/D in teleosts as in mammals.

Fludarabine and Exposure-Targeted Busulfan Compares Favorably with Busulfan/Cyclophosphamide-Based Regimens in Pediatric Hematopoietic
Cell Transplantation: Maintaining Efficacy with Less Toxicity

I.H. Bartelink, E.M.L. van Reij, C.E. Gerhardt, E.M. van Maarseveen, et al
Biol Blood Marrow Transplant 20 (2014) 345e353
http://dx.doi.org/10.1016/j.bbmt.2013.11.027

Busulfan (Bu) is used as a myeloablative agent in conditioning regimens before allogeneic hematopoietic cell transplantation (allo-HCT). In line with strategies explored in adults, patient outcomes may be optimized by replacing cyclophosphamide (Cy) with or without melphalan (Mel) with fludarabine (Flu). We compared outcomes in 2 consecutive cohorts of HCT recipients with a nonmalignant HCT indication, a myeloid malignancy, or a lymphoid malignancy with a contraindication for total body irradiation (TBI). Between 2009 and 2012, 64 children received Flu + Bu at a target dose of 80-95 mg-h/L, and between 2005 and 2008, 50 children received Bu targeted to 74-80 mg-h/L þ Cy. In the latter group, Mel was added for patients with myeloid malignancy (n = 12). Possible confounding effects of calendar time were studied in 69 patients receiving a myeloablative dose of TBI between 2005 and 2012. Estimated 2-year survival and event-free survival were 82% and 78%, respectively, in the FluBu arm and 78% and 72%, respectively, in the BuCy (Mel) arm (P, not significant). Compared with the BuCy (Mel) arm, less toxicity was noted in the FluBu arm, with lower rates of acute (noninfectious) lung injury (16% versus 36%; P < .007), veno-occlusive disease (3% versus 28%; P < .003), chronic graft-versus-host disease (9% versus 26%; P < .047), adenovirus infection (3% versus 32%; P < .001), and human herpesvirus 6 infection reactivation (21% versus 44%; P < .005). Furthermore, the median duration of neutropenia was shorter in the FluBu arm (11 days versus 22 days; P < .001), and the patients in this arm required fewer transfusions. Our data indicate that Flu (160 mg/m2) with targeted myeloablative Bu (90 mg-h/L) is less toxic than and equally effective
as BuCy (Mel) in patients with similar indications for allo-HCT.

Fibrotic and Sclerotic Manifestations of Chronic Graft-versus-Host Disease

Carrie L. Kitko, Eric S. White, Kristin Baird
Biol Blood Marrow Transplant 18:S46-S52, 2012
http://dx.doi.org:/10.1016/j.bbmt.2011.10.021

Chronic graft-versus-host disease (cGVHD) is a common cause of morbidity
and mortality following allogeneic stem cell transplantation (HCT), with approximately 50% to 60% of long-term HCT survivors developing one or more manifestations of the disorder. Although acute GVHD is typically limited to skin, liver, and gastrointestinal involvement, virtually every organ is at risk for the development of cGVHD. Although the pathophysiology of cGVHD remains poorly understood, some of the most severe organ manifestations are linked by end-organ fibrosis. In particular, fibrotic cutaneous and bronchiolar changes, resulting in scleroderma-like changes and bronchiolitis obliterans syndrome (BOS), respectively, are two of the most devastating outcomes for these patients. Both sclerotic GVHD (ScGVHD) and BOS have been reported in 5% to 15% of patients with cGVHD.

Many of the manifestations of cGVHD share clinical characteristics seen in nontransplant conditions, including systemic sclerosis or pulmonary fibrosis. Thus, understanding the pathophysiology underlying these related conditions may help identify potential mechanisms and ultimately new therapeutic options for patients with cGVHD.

Tyrosine kinase inhibitors (TKIs) have been shown to inhibit two different profibrotic pathways (transforming growth factor β [TGF-β] and platelet-derived growth factor [PDGF]) in various mouse models of fibrotic disease and offer a possible novel treatment approach for cGVHD patients suffering from severe sclerosis. Likewise, overexpression of TNF-α has been shown to induce fibrogenesis in experimental hepatocellular disease and has been linked with human scleroderma-associated interstitial pulmonary fibrosis and profibrotic responses in human osteoarthritic hip joint fibroblasts. The use of TNF antagonists has been examined in some clinical situations associated with fibrosis, suggesting they may also be of some benefit to patients with cGVHD; however, this must first be prospectively tested.

Table. Proposed Modifications to NIH BOS Clinical Definition

Absence of infection (no change)
Another cGVHD manifestation in another organ (no change)
FEV1 <75% predicted (no change) or >10% decline from pre-HCT value (modification)
Signs of Obstruction
FEV1/SVC ratio <0.7 (modification), or
RV >120% predicted (no change), or
RV/TLC >120% (modification), and
HRCT with evidence of air trapping (no change)

SVC indicates slow vital capacity; RV, residual volume; TLC, total lung capacity; HRCT, high-resolution computed tomography

Figure (not shown)
Effect of etanercept on survival in post-HCT patients with subacute lung injury. (A) Overall 5-year survival by pulmonary function testing defect. Patients with an obstructive defect (solid line) had a 5-year survival of 67% compared with 44% in those with a restrictive lung defect (dashed line) (P 5 .19). (B) Overall 5-year survival by response to therapy. Patients who responded to etanercept therapy (solid line) had a 5-year survival of 90% compared with 55% in patients who failed to respond (dashed line) (P 5.07). (Figures reprinted with permission, Biol Blood and Marrow Trans).

Extensive, sclerotic skin changes with superficial or deep subcutaneous or fascial involvement are seen in approximately 4% to 13% of patients with cGVHD and can be a life-threatening manifestation. ScGVHD of the skin includes several cutaneous presentations characterized by inflammation and progressive fibrosis of the dermis and subcutaneous tissues. These changes can resemble morphea, systemic sclerosis, or eosinophilic fasciitis and may or may not occur in the setting of concurrent overlying epidermal GVHD. When severe, ScGVHD can result in contractures, severe wasting, and chest wall restriction.

Development of clinical trials for patients with cGVHD is difficult because of the complexity and heterogeneity of disease, variable approaches to treatment, and the lack of standardized assessments of disease. In particular, the study of ScGVHD lacks universally accepted measures of disease burden and response. Investigators have used several measures to assess ScGVHD involvement including body surface area, magnetic resonance imaging, ultrasound, and range-of-motion measurements. Additionally, investigators have tried to apply the Rodnan score, the standardmeasure for skin involvement in scleroderma. Thus far, none of these measures has proven
to be completely reliable in the setting of ScGVHD, and it is likely that multiple measures will need to be integrated into the assessment of ScGVHD.

Imatinib mesylate (Gleevec in the US; Glivec in Europe, Australia, and Latin America, marketed by Novartis) is a TKI that has biological activity against both PDGF and TGF-β signaling pathways. Both cytokines have been implicated in the pathogenesis of several fibrosing diseases, including hepatic, renal, and lung, as well as in scleroderma, a disease that closely resembles ScGVHD. In addition, stimulatory antibodies specific for the PDGF receptor (PDGFR) were identified in a series of 39 patients with extensive cGVHD with higher levels detected in those patients with skin involvement. Similar stimulatory antibodies targeting PDGFR have been reported in patients with scleroderma, suggesting an important therapeutic target for these fibrosing conditions. Imatinib mesylate has particularly potent activity against PDGF and is FDA approved in the United States for the treatment of several disorders associated with aberrant PDGFR signaling. The side effect profile of the drug is well established in non-HCT patients, which is helpful in the setting of a therapy for allogenic HCT patients, many of whom have multiorgan system symptoms and possible dysfunction and who will require ongoing immunosuppressive therapy.

Through the efforts of the Chronic GVHD Consortium, led by Stephanie Lee at the Fred Hutchinson Cancer Research Center, there is a multicenter, ongoing prospective evaluation of the NIH diagnostic and assessment tools. This effort has already resulted in several publications that have further refined essential criteria for cGVHD evaluation, including organ-specific manifestations such as BOS and ScGVHD. Currently, the Consortium is conducting a multicenter prospective clinical trial of fluticasone propionate, azithromycin, and montelukast for the treatment of BOS (ClinicalTrials.gov NCT01307462); a separate trial of imatinib versus rituximab for treatment of ScGVHD is also enrolling subjects (ClinicalTrials.gov NCT01309997).

Although cGVHD remains a significant problem for many long-term survivors of HCT, critical advances in cGVHD research and treatment can be achieved by cooperative group efforts such as those put forth by the Chronic GVHD Consortium and the Clinical Trials Network.

Hematopoietic stem cell transplantation (HSCT): An approach to autoimmunity

Carmen Alaez, Mariana Loyola, Andrea Murguıa, Hilario Flores, et al.
Autoimmunity Reviews 5 (2006) 167– 179
http://dx.doi.org:/10.1016/j.autrev.2005.06.003

HSCT provides the opportunity to replace a damaged tissue. It is the most important treatment for high risk hematologic malignant and nonmalignant disorders. An important challenge in the identification of matched donors/patients is the HLA diversity. The Mexican Bone Marrow Registry (DONORMO) has nowadays N5000 donors. The prevalent alleles are Amerindian, Mediterranean (Semitic and Spanish genes) and African. In theory, it is possible to find 11% of 6/6 A–B–DR low resolution matches for 70% of patients with Mexican ancestry. We contributed with 39 unrelated, cord blood and autologous HSCT for patients with malignant, genetic and autoimmune disorders. Overall disease survival was 50% (2–7 years) depending on the initial diagnosis, conditioning, disease evolution or other factors. Clinical studies using autologous and unrelated HSC are performed on patients with refractory autoimmune diseases producing mixed results: mainly, T1D, RA, MS, SLE. Improvement has been observed in skin damage and quality of life in SLE and systemic sclerosis. Disease stabilization in 2/3 of MS patients. However, in RA and T1D, initial benefits have been followed by eventual relapse. With growing clinical experience and protocol improvement, treatment-related mortality is decreasing. Proof efficacy will be achieved by comparing HSCT with standard therapy in autoimmunity.

Monoclonal Antibody-Mediated Targeting of CD123, IL-3 Receptor α Chain, Eliminates Human Acute Myeloid Leukemic Stem Cells

Liqing Jin, Erwin M. Lee, Hayley S. Ramshaw, Samantha J. Busfield, et al.
Cell: Stem Cell 5, 31–42, July 2, 2009
http://dx.doi.org:/10.1016/j.stem.2009.04.018

Leukemia stem cells (LSCs) initiate and sustain the acute myeloid leukemia (AML) clonal hierarchy and possess biological properties rendering them resistant to conventional chemotherapy. The poor survival of AML patients raises expectations that LSC-targeted therapies might achieve durable remissions. We report that an anti-interleukin-3 (IL-3) receptor α chain (CD123)-neutralizing antibody (7G3) targeted AML-LSCs, impairing homing
to bone marrow (BM) and activating innate immunity of nonobese diabetic/ severe-combined immunodeficient (NOD/SCID) mice. 7G3 treatment profoundly reduced AML-LSC engraftment and improved mouse survival.
Mice with preestablished disease showed reduced AML burden in the BM
and periphery and impaired secondary transplantation upon treatment, establishing that AMLLSCs were directly targeted. 7G3 inhibited IL-3-mediated intracellular signaling of isolated AML CD34+ CD38[1] cells in vitro and reduced their survival. These results provide clear validation for therapeutic monoclonal antibody (mAb) targeting of AML-LSCs and for translation of in vivo preclinical research findings toward a clinical application.

Many Days at Home during Neutropenia after Allogeneic Hematopoietic Stem Cell Transplantation Correlates with Low Incidence of Acute Graft-versus-Host Disease

Olle Ringdén, Mats Remberger, Katarina Holmberg, Charlotta Edeskog, et al.
Biol Blood Marrow Transplant 19 (2013) 314e320
http://dx.doi.org/10.1016/j.bbmt.2012.10.011

Patients are isolated in the hospital during the neutropenic phase after allogeneic hematopoietic stem cell transplantation. We challenged this by allowing patients to be treated at home. A nurse from the unit visited and checked the patient. One hundred forty-six patients treated at home were compared with matched hospital control subjects. Oral intake was intensified from September 2006 and improved (P < .002). We compared 4 groups: home care and control subjects before and after September 2006. The cumulative incidence of acute graft-versus-host disease (GVHD) of grades II to IV was 15% in the “old” home care group, which was significantly lower than that of 32% to 44% in the other groups (P <.03). Transplantation-related mortality, chronic GVHD, and relapse were similar in the groups. The “new” home care patients spent fewer days at home (P < .002). In multivariate analysis, GVHD of grades 0 to I was associated with home care (hazard ratio [HR], 2.46; P <.02) and with days spent at home (HR, .92; P < .005) but not with oral nutrition (HR, .98; P = .13). Five year survival was 61% in the home care group as compared with 49% in the control subjects (P < .07). Home care is safe. Home care and many days spent at home were correlated with a low risk of acute GVHD.

Impact on Outcomes of Human Leukocyte Antigen Matching by Allele-Level Typing in Adults with Acute Myeloid Leukemia Undergoing Umbilical Cord Blood Transplantation

Jaime Sanz, Francisco J. Jaramillo, Dolores Planelles, Pau Montesinos, et al.
Biol Blood Marrow Transplant 20 (2014) 106e110
http://dx.doi.org/10.1016/j.bbmt.2013.10.016

This retrospective study analyzed the impact of directional donor-recipient human leukocyte antigen (HLA) disparity using allele-level typing at HLA-A, -B, -C, and -DRB1 in 79 adults with acute myeloid leukemia (AML) who received single-unit umbilical cord blood (UCB) transplant at a single institution. With extended high resolution HLA typing, the donor-recipient compatibility ranged from 2/8 to 8/8. HLA disparity showed no negative impact on nonrelapse mortality (NRM), graft-versus-host (GVH) disease or engraftment. Considering disparities in the GVH direction, the 5-year cumulative incidence of relapse was 44% and 22% for patients receiving an UCB unit matched > 6/8 and < 6/8, respectively (P <.04). In multivariable analysis, a higher HLA disparity in the GVH direction using extended high-resolution typing (Risk ratio [RR] 2.8; 95% confidence interval [CI], 1.5 to 5.1; P ¼.0009) and first complete remission at time of transplantation (RR 2.1; 95% CI, 1.2 to 3.8; P < .01) were the only variables significantly associated with an improved disease-free survival. In conclusion, we found that in adults with AML undergoing single-unit UCBT, an increased number of HLA disparities at allele-level typing improved disease-free survival by decreasing the relapse rate without a negative effect on NRM.

HLA mismatch direction in cord blood transplantation: impact on outcome and implications for cord blood unit selection
Cladd E. Stevens, C Carrier, C Carpenter, D Sung, and A Scaradavou

Blood. 2011; 118(14):3969-3978
http://dx.doi.org:/10.1182/blood-2010-11-317271

Donor-recipient human leukocyte antigen mismatch level affects the outcome of unrelated cord blood (CB) transplantation. To identify possible “permissive” mismatches, we examined the relationship between direction of human leukocyte antigen mismatch (“vector”) and transplantation outcomes in 1202 recipients of single CB units from the New York Blood Center National Cord Blood Program treated in United States Centers from 1993-2006. Altogether, 98 donor/patient pairs had only unidirectional mismatches: 58 in the graft-versus-host (GVH) direction only (GVH-O) and 40 in the host-versus-graft or rejection direction only (R-O). Engraftment was faster in patients with GVH-O mismatches compared with those with 1 bidirectional mismatch (hazard ratio [HR] = 1.6, P < .003). In addition, patients with hematologic malignancies given GVH-O grafts had lower transplantation-related mortality (HR = 0.5, P < .062), overall mortality (HR = 0.5, P < .019), and treatment failure (HR = 0.5, P < .016), resulting in outcomes similar to those of matched CB grafts. In contrast, R-O mismatches had slower engraftment, higher graft failure, and higher relapse rates (HR = 2.4, P < .010). Based on our findings, CB search algorithms should be modified to identify unidirectional mismatches. We recommend that transplant centers give priority to GVH-O-mismatched units over other mismatches and avoid selecting R-O mismatches, if possible.

Mutation of the NPM1 gene contributes to the development of donor cell–derived acute myeloid leukemia after unrelated cord blood transplantation
for acute lymphoblastic leukemia

G Rodríguez-Macías, C Martínez-Laperche, J Gayoso, V Noriega, .., Ismael Buño
Human Pathology (2013) 44, 1696–1699
http://dx.doi.org/10.1016/j.humpath.2013.01.001

Donor cell leukemia (DCL) is a rare but severe complication after allogeneic stem cell transplantation. Its true incidence is unknown because of a lack of correct recognition and reporting, although improvements in molecular analysis of donor-host chimerism are contributing to a better diagnosis of this complication. The mechanisms of leukemogenesis are unclear, and multiple factors can contribute to the development of DCL. In recent years, cord blood has emerged as an alternative source of hematopoietic progenitor cells, and at least 12 cases of DCL have been reported after unrelated cord blood transplantation. We report a new case of DCL after unrelated cord blood transplantation in a 44-year-old woman diagnosed as having acute lymphoblastic leukemia with t(1;19) that developed acute myeloid leukemia with normal karyotype and nucleophosmin (NPM1) mutation in donor cells. To our knowledge, this is the first report of NPM1 mutation contributing to DCL development.

Graft-versus-leukemia in the bone marrow
Blood, 23 JAN 2014; 123(4)
http://imagebank.hematology.org.

63-year-old female with relapsed acute myeloid leukemia (AML) after allogeneic stem cell transplantation reached CR2 after re-induction therapy followed by consolidation with donor lymphocyte infusions: 3 x 10⁷/kg and 3 x 10⁸/kg after 1 and 2.5 months, respectively. No signs of graft-versus-host disease were observed at this time. At 5 months follow-up, her blood count deteriorated: hemoglobin: 6.9 mmol/L, thrombocytes: 58 x 10⁹/L and leukocytes: 1.37 x 10⁹/L. Bone marrow aspirate was not evaluable. Bone marrow trephine biopsy showed relapse AML with hypercellularity in the H&E staining (340 objective lens, panel A) and 20% CD341 blast cells without any signs of maturation (panel B). Also, a high number of CD3 positive T cells (panel C) was noted, intermingling with the CD34 positive blasts, both staining positively with CD43 (panel D). Only supportive care was given. However, normalization of the blood count was observed in the following months and she developed graft-versus-host disease of the lung, which was treated with ciclosporin and prednisone. A bone marrow aspirate performed 3 months after relapse showed a third remission with 0.8% myeloid blasts. In retrospect, one could therefore consider the picture of the bone marrow trephine biopsy at the second relapse as graft-versus-leukemia in the bone marrow.

GVL- panel A

GVL – panel B

GVL – panel C

Long-Term Outcomes of Alemtuzumab-Based Reduced-Intensity Conditioned Hematopoietic Stem Cell Transplantation for Myelodysplastic Syndrome and Acute Myelogenous Leukemia Secondary to Myelodysplastic Syndrome

Victoria T. Potter, Pramila Krishnamurthy, Linda D. Barber, ZiYi Lim, et al.
Biol Blood Marrow Transplant 20 (2014) 111e117
http://dx.doi.org/10.1016/j.bbmt.2013.10.021

Allogeneic hematopoietic stem cell transplantation (HSCT) with reduced-intensity conditioning (RIC) offers a potential cure for patients with myelodysplastic syndrome (MDS) who are ineligible for standard-intensity regimens. Previously published data from our institution suggest excellent outcomes at 1 yr using a uniform fludarabine, busulfan, and alemtuzumab-based regimen. Here we report long-term follow-up of 192 patients with MDS and acute myelogenous leukemia (AML) secondary to MDS (MDS-AML) transplanted with this protocol, using sibling (n = 45) or matched unrelated (n = 147) donors. The median age of the cohort was 57 yr (range, 21 to 72 yr), and median follow-up was 4.5 yr (range, 0.1 to 10.6 yr). The 5-yr overall survival (OS), event-free survival, and nonrelapse mortality were 44%, 33%, and 26% respectively. The incidence of de novo chronic graft-versus-host disease (GVHD) was low at 19%, illustrating the efficacy of alemtuzumab for GVHD prophylaxis. Conversely, the 5-yr relapse rate was 51%. For younger patients (age <50 yr), the 5-yr OS and relapse rates were 58% and 39%, respectively. On multivariate analysis, advanced age predicted significantly worse outcomes, with patients age >60 yr having a 5-yr OS of 15% and relapse rate of 66%. Patients receiving preemptive donor lymphocyte infusions had an impressive 5-yr OS of 67%, suggesting that this protocol may lend itself to the incorporation of immunotherapeutic strategies. Overall, these data demonstrate good 5-yr OS for patients with MDS and MDS-AML undergoing alemtuzumab-based RIC-HSCT. The low rate of chronic GVHD is encouraging, and comparative studies with other RIC protocols are warranted.

Natural killer cell activity influences outcome after T cell depleted stem cell transplantation from matched unrelated and haploidentical donors

Peter Lang, Matthias Pfeiffer, Heiko-Manuel Teltschik, Patrick Schlegel, et al.
Best Practice & Research Clinical Haematology 24 (2011) 403–411
http://dx.doi.org:/10.1016/j.beha.2011.04.009

Lytic activity and recovery of natural killer (NK) cells was monitored in pediatric patients with leukemias (ALL, AML, CML, JMML) and myelodysplastic syndromes after transplantation of T cell depleted stem cells from matched unrelated (n = 18) and mismatched related (haploidentical, n = 29) donors. CD34⁺ selection with magnetic microbeads resulted in 8 x 103/kg residual T cells. No post-transplant immune suppression was given. NK cells recovered rapidly after transplantation (300 CD56⁺/mL at day 30, median), whereas T cell recovery was delayed (median: 12 CD3⁺/mL at day 90). NK activity was measured as specific lysis of K 562 targets several times (mean: 3 assays per patient). Four temporal patterns of lytic activity could be differentiated: consistently low, consistently high, decreasing and increasing activity. Patients with consistently high or increasing activity had significantly lower relapse probability than patients with consistently low or decreasing levels (0.18 vs 0.73 at 2 years, p < 0.05). The subgroup of patients with ALL showed similar results (0.75 vs 0.14 at 2 years, p < 0.05). Speed of T cell recovery had no influence. These data suggest that both achieving and maintaining a high level of NK activity may contribute to prevent relapse. Since NK activity could be markedly increased by in vitro stimulation with Interleukin 2 (IL-2), in vivo administration should be considered.

Graft-versus-host disease: Pathogenesis and clinical manifestations of graft-versus-host disease

Sharon R. Hymes, Amin M. Alousi, and Edward W. Cowen
J Am Acad Dermatol 2012; 66: 515.e1-18.

Graft-versus-host disease is the primary cause of morbidity and nonerelapse related mortality in patients who undergo allogeneic hematopoietic cell transplantation.
Acute graft-versus-host disease manifests as a skin exanthem, liver dysfunction, and gastrointestinal involvement.
Chronic graft-versus-host disease of the skin is remarkably variable in its clinical presentation.
Chronic graft-versus-host disease is a multisystem disorder that may affect nearly any organ; the most common sites are the skin, oral mucosa, and eyes.

Key points

Allogeneic transplantation is in widespread use for hematologic malignancies, but is also increasingly used for marrow failure syndromes, immunodeficiencies, and other life-threatening conditions

Graft-versus-host disease is the primary cause of morbidity and nonerelapse related mortality after allogeneic hematopoietic cell transplantation
Minimizing graft-versus-host disease without losing the graft-versus-tumor effect is an area of active research
The skin is the most common organ affected in patients with graft-versus-host disease

Outcomes of Thalassemia Patients Undergoing Hematopoietic Stem Cell Transplantation by Using a Standard Myeloablative versus a Novel Reduced-Toxicity Conditioning Regimen According to a New Risk Stratification

Usanarat Anurathapan, S Pakakasama, P Mekjaruskul, N Sirachainan, et al.
Biol Blood Marrow Transplant 20 (2014) 2056e2075
http://dx.doi.org/10.1016/j.bbmt.2014.07.016

Improving outcomes among class 3 thalassemia patients receiving allogeneic hematopoietic stem cell transplantations (HSCT) remains a challenge. Before HSCT, patients who were > 7 years old and had a liver size > 5 cm constitute what the Center for International Blood and Marrow Transplant Research defined as a very high risk subset of a conventional high-risk class 3 group (here referred to as class 3 HR). We performed HSCT in 98 patients with related and unrelated donor stem cells. Seventy-six of the patients with age < 10 years received the more conventional myeloablative conditioning (MAC) regimen (cyclophos-phamide, busulfan, + fludarabine); the remaining 22 patients with age > 10 years and hepatomegaly (class 3 HR), and in several instances additional comorbidity problems, underwent HSCT with a novel reduced-toxicity conditioning (RTC) regimen (fludarabine and busulfan). We then compared the outcomes between these 2 groups (MAC versus RTC). Event-free survival (86% versus 90%) and overall survival (95% versus 90%) were not significantly different between the respective groups; however, there was a higher incidence of serious treatment-related complications in the MAC group, and although we experienced 6 graft failures in the MAC group (8%), there were none in the RTC group. Based on these results, we suggest that (1) class 3HRthalassemia patients can safely receive HSCT with our novel RTC regimen and achieve the same excellent outcome as low/standard-risk thalassemia patients who received the standard MAC regimen, and further, (2) that this novel RTC approach should be tested in the low/standard-risk patient population.

Pharmacological Immunosuppression Reduces But Does Not Eliminate the Need for Total-Body Irradiation in Nonmyeloablative Conditioning Regimens for Hematopoietic Cell Transplantation

Marco Mielcarek, Beverly Torok-Storb, Rainer Storb
Biol Blood Marrow Transplant 17: 1255-1260 (2011)
http://dx.doi.org:/10.1016/j.bbmt.2011.01.003

In the dog leukocyte antigen (DLA)-identical hematopoietic cell transplantation (HCT) model, stable marrow engraftment can be achieved with total-body irradiation (TBI) of 200 cGy when used in combination with postgrafting immunosuppression. The TBI dose can be reduced to 100 cGy without compromising engraftment rates if granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (G-PBMC) are infused with the marrow. T cell-depleting the G-PBMC product abrogates this effect. These results were interpreted to suggest that the additional T cells provided with G-PBMC facilitated engraftment by overcoming host resistance.We therefore hypothesized that the TBI dose may be further reduced to 50 cGy by augmenting immunosupression either by (1) tolerizing or killing recipient T cells, or (2) enhancing the graft-versus-host (GVH) activity of donor T cells. To test the first hypothesis, recipient T cells were activated before HCT by repetitive donor-specific PBMC infusions followed by administration of methotrexate (MTX) (n 5 5), CTLA4-Ig (n = 4), denileukin diftitox (Ontak; n = 4), CTLA4-Ig 1 MTX (n = 8), or 5c8 antibody (anti-CD154) 1 MTX (n = 3). To test the second hypothesis, recipient dendritic cells were expanded in vivo by infusion of Flt3 ligand given either pre-HCT (n = 4) or pre- and post-HCT (n = 5) to augment GVH reactions. Although all dogs showed initial allogeneic engraftment, sustained engraftment was seen in only 6 of 42 dogs (14% of all dogs treated in 9 experimental groups). Hence, unless more innovative pharmacotherapy can be developed that more forcefully shifts the immunologic balance in favor of the donor, noncytotoxic immunosuppressive drug therapy as the sole component of HCT preparative regimens may not suffice to ensure sustained engraftment.

Pretransplant Immunosuppression followed by Reduced-Toxicity Conditioning and Stem Cell Transplantation in High-Risk Thalassemia: A Safe Approach to Disease Control

Usanarat Anurathapan, S Pakakasama, P Rujkijyanont, N Sirachainan, et al.
Biol Blood Marrow Transplant 19 (2013) 1254e1270
http://dx.doi.org/10.1016/j.bbmt.2013.04.023

Patients with class 3 thalassemia with high-risk features for adverse events after high-dose chemotherapy with hematopoietic stem cell transplantation (HSCT) are difficult to treat, tending to either suffer serious toxicity or fail to establish stable graft function. We performed HSCT in 18 such patients age 7 years and hepatomegaly using a novel approach with pretransplant immunosuppression followed by a myeloablative reduced-toxicity conditioning regimen (fludarabine and i.v. busulfan [Flu-IV Bu]) and then HSCT. The median patient age was 14 years (range, 10 to 18 years). Before the Flu-IV Bu þ antithymocyte globulin conditioning regimen, all patients received 1 to 2 cycles of pretransplant immunosuppression with fludarabine and dexamethasone. Thirteen patients received a related donor graft, and 5 received an unrelated donor graft. An initial prompt engraftment of donor cells with full donor chimerism was observed in all 18 patients, but 2 patients developed secondary mixed chimerism that necessitated withdrawal of immunosuppression to achieve full donor chimerism. Two patients (11%) had acute grade III-IV graft-versus-host disease, and 5 patients had limited chronic graft-versus-host disease. The only treatment-related mortality was from infection, and with a median follow-up of 42 months (range, 4 to 75), the 5-year overall survival and thalassemia-free survival were 89%. We conclude that this novel sequential immunoablative pretransplant-ation conditioning program is safe and effective for patients with high-risk class 3 thalassemia exhibiting additional comorbidities.

Profiling antibodies to class II HLA in transplant patient sera

Curtis McMurtrey, D Lowe, R Buchli, S Daga, D Royer, A Humphrey, et al.
Human Immunology 75 (2014) 261–270
http://dx.doi.org/10.1016/j.humimm.2013.11.015

Immunizing events including pregnancy, transfusions, and transplantation promote strong alloantibody responses to HLA. Such alloantibodies to HLA preclude organ transplantation, foster hyperacute rejection, and contribute to chronic transplant failure. Diagnostic antibody-screening assays detect alloreactive antibodies, yet key attributes including antibody concentration and isotype remain largely unexplored. The goal here was to provide a detailed profile of allogeneic antibodies to class II HLA. Methodologically, alloantibodies were purified from sensitized patient sera using an HLA-DR11 immunoaffinity column and subsequently categorized. Antibodies to DR11 were found to fix complement, exist at a median serum concentration of 2.3 lg/mL, consist of all isotypes, and isotypes IgG2, IgM, and IgE were elevated. Because multimeric isotypes can confound diagnostic determinations of antibody concentration, IgM and IgA isotypes were removed and DR11-IgG tested alone. Despite removal of multimeric isotypes, patient-to patient antibody concentra-tions did not correlate with MFI values. In conclusion, allogeneic antibody responses to DR11 are comprised of all antibody isotypes at differing proportions, these combined isotypes fix complement at nominal serum concentrations, and enhancements other than the removal of IgM and IgA multimeric isotypes may be required if MFI is to be used as a means of determining anti-HLA serum antibody concentrations in diagnostic clinical assays.

Reduced-intensity conditioning and HLA-matched hemopoietic stem-cell transplantation in patients with chronic granulomatous disease: a prospective multicenter study

Tayfun Güngör, P Teira, M Slatter, G Stussi, P Stepensky, D Moshous, et al.
Lancet 2014; 383: 436–48
http://dx.doi.org/10.1016/S0140-6736(13)62069-3

Background In chronic granulomatous disease allogeneic hemopoietic stem-cell transplantation (HSCT) in adolescents and young adults and patients with high-risk disease is complicated by graft-failure, graft-versus-host disease (GVHD), and transplant-related mortality. We examined the effect of a reduced-intensity conditioning regimen designed to enhance myeloid engraftment and reduce organ toxicity in these patients. Methods This prospective study was done at 16 centers in ten countries worldwide. Patients aged 0–40 years with chronic granulomatous disease were assessed and enrolled at the discretion of individual centers. Reduced-intensity conditioning consisted of high-dose fludarabine (30 mg/m² [infants <9 kg 1∙2 mg/kg]; one dose per day on days –8 to –3), serotherapy (anti-thymocyte globulin [10 mg/kg, one dose per day on days –4 to –1; or thymoglobulin 2·5 mg/kg, one dose per day on days –5 to –3]; or low-dose alemtuzumab [<1 mg/kg on days –8 to –6]), and low-dose (50–72% of myeloablative dose) or targeted busulfan administration (recommended cumulative area under the curve: 45–65 mg/L × h). Busulfan was administered mainly intravenously and exceptionally orally from days –5 to –3. Intravenous busulfan was dosed according to weight-based recommendations and was administered in most centers (ten) twice daily over 4 h. Unmanipulated bone marrow or peripheral blood stem cells from HLA-matched related donors or HLA-9/10 or HLA-10/10 matched unrelated-donors were infused. The primary endpoints were overall survival and event-free survival (EFS), probabilities of overall survival and EFS at 2 years, incidence of acute and chronic GVHD, achievement of at least 90% myeloid donor chimerism, and incidence of graft failure after at least 6 months of follow-up. Findings 56 patients (median age 12∙7 years; IQR 6·8–17·3) with chronic granulomatous disease were enrolled from June 15, 2003, to Dec 15, 2012. 42 patients (75%) had high-risk features (ie, intractable infections and autoinflammation), 25 (45%) were adolescents and young adults (age 14–39 years). 21 HLA-matched related-donor and 35 HLA-matched unrelated-donor transplants were done. Median time to engraftment was 19 days (IQR 16–22) for neutrophils and 21 days (IQR 16–25) for platelets. At median follow-up of 21 months (IQR 13–35) overall survival was 93% (52 of 56) and EFS was 89% (50 of 56). The 2-year probability of overall survival was 96% (95% CI 86∙46–99∙09) and of EFS was 91% (79∙78–96∙17). Graft-failure occurred in 5% (three of 56) of patients. The cumulative incidence of acute GVHD of grade III–IV was 4% (two of 56) and of chronic graft-versus-host disease was 7% (four of 56). Stable (≥90%) myeloid donor chimerism was documented in 52 (93%) surviving patients. Interpretation This reduced-intensity conditioning regimen is safe and efficacious in high-risk patients with chronic granulomatous disease.

Refinement of the Definition of Permissible HLA-DPB1 Mismatches with Predicted Indirectly ReCognizable HLA-DPB1 Epitopes

Kirsten A. Thus, MTA Ruizendaal, TA de Hoop, Eric Borst, et al.
Biol Blood Marrow Transplant 20 (2014) 1705e1710
http://dx.doi.org/10.1016/j.bbmt.2014.06.026

Hematopoietic stem cell transplantation with HLA-DPB1emismatched donors leads to an increased risk of acute graft-versus-host disease (GVHD). Studies have indicated a prognostic value for classifying HLA-DPB1 mismatches based on T cell epitope (TCE) groups. The aim of this study was to determine the contribution of indirect recognition of HLA-DPe derived epitopes, as determined with the Predicted Indirectly ReCognizable HLA Epitopes (PIRCHE) method. We therefore conducted a retrospective single-center analysis on 80 patients transplanted with a 10/10 matched unrelated donor that was HLA-DPB1 mismatched. HLADPB1 mismatches that were classified as GVH nonpermissive by the TCE algorithm correlated to higher numbers of HLA class I as well as HLA class II presented PIRCHE (PIRCHE-I and -II) compared with permissive or host-versus-graft nonpermissive mismatches. Patients with acute GVHD grades II to IV presented significantly higher numbers of PIRCHE-I compared with patients without acute GVHD (P < .05). Patients were divided into 2 groups based on the presence or absence of PIRCHE. Patients with PIRCHE-I or -II have an increased hazard of acute GVHD when compared with patients without PIRCHE-I or -II (hazard ratio [HR], 3.19; 95% confidence interval [CI], 1.10 to 9.19; P <.05; and HR, 4.07; 95% CI, .97 to 17.19; P < .06, respectively). Patients classified as having an HLA-DPB1 permissive mismatch by the TCE model had an increased risk of acute GVHD when comparing presence of PIRCHE-I with absence of PIRCHE-I (HR, 2.96; 95% CI, .84 to 10.39; P < .09). We therefore conclude that the data presented in this study describe an attractive and feasible possibility to better select permissible HLA-DPB1 mismatches by including both a direct and an indirect recognition model.

Treosulfan-Thiotepa-FludarabineeBased Conditioning Regimen for
Allogeneic Transplantation in Patients with Thalassemia Major: A
Single-Center Experience from North India

Dharma Choudhary, SK Sharma, N Gupta,…, Satyendra Katewa
Biol Blood Marrow Transplant 19 (2013) 492e503
http://dx.doi.org/10.1016/j.bbmt.2012.11.007

Hematopoietic stem cell transplantation (HSCT) is the definite treatment
for patients with thalassemia major. A busulfan (Bu) and cyclophosphamide
(Cy)ebased regimen has been the standard myeloablative chemotherapy,
but it is associated with higher treatment-related toxicity, particularly in
patients classified as high risk by the Pesaro criteria. Treosulfan-based
conditioning regimens have been found to be equally effective and less
toxic. Consequently, we analyzed the safety and efficacy of treosulfan/
thiotepa/fludarabine (treo/thio/flu)-based conditioning regimens for
allogeneic HSCT in patients with thalassemia major between February
2010 and September 2012. We compared those results retrospectively
with results in patients who underwent previous HSCT with a Bu/Cy/
antithymocyte globulin (ATG)ebased conditioning regimen. A treo/thio/
flu-based conditioning regimen was used in 28 consecutive patients with
thalassemia major. The median patient age was 9.7 years (range, 2-18
years), and the mean CD34+ stem cell dose was 6.18 x 106/kg. Neutrophil
and platelet engraftment occurred at a median of 15 days (range, 12-23
days) and 21 days (range, 14-34 days), respectively. Three patients
developed veno-occlusive disease, 4 patients developed acute graft
versus-host disease (GVHD), and 2 patients had chronic GVHD. Treatment-
related mortality (TRM) was 21.4%. Two patients experienced secondary
graft rejection. We compared these results with results in patients who
underwent previous HSCT using a Bu/Cy/ATG-based conditioning regimen.
Twelve patients were treated with this protocol, at a median age of 7.2
years (range, 2-11 years). One patient had moderate veno-occlusive disease,
2 patients developed acute GVHD, 2 patients had chronic GVHD, and 2
patients experienced graft rejection. There was no TRM in this group. We
found no significant differences between the 2 groups (treo/thio/flu vs Bu/
Cy/ATG) in terms of the incidence of acute GVHD, chronic GVHD, TRM,
and graft failure, although a trend toward higher TRM was seen with the
treo/thio/flu regimen.

Graft-versus-Host Disease
James L.M. Ferrara, John E. Levine, Pavan Reddy, and Ernst Holler
Lancet. 2009 May 2; 373(9674): 1550–1561
http:dx.doi.org:/10.1016/S0140-6736(09)60237-3

The number of allogeneic hematopoietic cell transplantations (HCT)
continues to increase with more than 25,000 allogeneic transplantations
performed annually. The graft-versus leukemia/ tumor (GVL) effect during
allogeneic HCT effectively eradicates many hematological malignancies.
The development of novel strategies that use donor leukocyte infusions,
non-myeloablative conditioning and umbilical cord blood (UCB)
transplantation have helped expand the indications for allogeneic HCT
over the last several years, especially among older patients. Improvements
in infectious prophylaxis, immunosuppressive medications, supportive care
and DNA-based tissue typing have also contributed to improved outcomes
after allogeneic HCT. Yet the major complication of allogeneic HCT, graft-
versus-host disease (GVHD), remains lethal and limits the use of this
important therapy. Given current trends, the number of transplants from
unrelated donors is expected to double within the next five years,
significantly increasing the population of patients with GVHD. In this
seminar we review advances made in identifying the genetic risk
factors and pathophysiology of this major HCT complication, as well
as its prevention, diagnosis and treatment.

Non-HLA Genetics—Despite HLA identity between a patient and donor,
approximately 40% of patients receiving HLA-identical grafts develop
acute GVHD due to genetic differences that lie outside the HLA loci,
or “minor” histocompatibility antigens (HA). Some minor HAs, such as HY
and HA-3, are expressed on all tissues and are targets for both GVHD
and GVL. Other minor HAs, such as HA-1 and HA-2, are expressed most
abundantly on hematopoietic cells (including leukemic cells) and may
therefore induce a greater GVL effect with less GVHD. Polymorphisms
in both donors and recipients for cytokines that are involved in the
classical `cytokine storm’ of GVHD have been implicated as risk factors
for GVHD. Tumor Necrosis Factor (TNF)-α, Interleukin 10 (IL-10),
Interferon-γ (IFNγ) variants have correlated with GVHD in some, but
not all, studies. Genetic polymorphisms of proteins involved in innate
immunity, such as nucleotide oligomerization domain 2 and Keratin 18
receptors, have also been associated with GVHD.

Future strategies to identify the best possible transplant donor will
probably incorporate both HLA and non-HLA genetic factors. Skin is most
commonly affected and is usually the first organ involved, often coinciding
with engraftment of donor cells. The characteristic maculopapular rash is
pruritic and can spread throughout the body, sparing the scalp. In severe
cases the skin may blister and ulcerate. Apoptosis at the base of epidermal
rete pegs is a characteristic pathologic finding. Other features include
dyskeratosis, exocytosis of lymphocytes, satellite lymphocytes adjacent
to dyskeratotic epidermal keratinocytes, and a perivascular lymphocytic
infiltration in the dermis.

Gastrointestinal tract involvement of acute GVHD usually presents as
diarrhea but may also include vomiting, anorexia, and/or abdominal pain
when severe. The diarrhea of GVHD is secretory and often voluminous
(greater than two liters per day). Bleeding, which carries a poor prognosis,
occurs as a result of mucosal ulceration but patchy involvement of the
mucosa often leads to a normal appearance on endoscopy.

The incidence of the severity of acute GVHD is determined by the extent
of involvement of three principal target organs. The overall grades are
classified as I (mild), II (moderate), III (severe) and IV (very severe). Severe
GVHD carries a poor prognosis, with 25% long term survival for grade III and
5% for grade IV. The incidence of acute GVHD is directly related to the
degree of mismatch between HLA proteins and ranges from 35-45% in
recipients of full matched sibling donor grafts to 60-80% in recipients of
one-antigen HLA mismatched unrelated donor grafts. The same degree
of mismatch causes less GVHD using UCB grafts and incidence of acute
GVHD is lower following the transplant of partially matched UCB units
and ranges from 35-65%.

Two important principles are important to consider regarding the
pathophysiology of acute GVHD. First, acute GVHD reflects exaggerated
but normal inflammatory mechanisms mediated by donor lymphocytes infused
into the recipient where they function appropriately, given the foreign
environment they encounter. Second, the recipient tissues that stimulate
donor lymphocytes have usually been damaged by underlying disease,
prior infections, and the transplant conditioning regimen. As
a result, these tissues produce molecules (sometimes referred to as
“danger” signals) that promote the activation and proliferation of donor
immune cells. Based largely on experimental models, the development
of acute GVHD can be conceptualized in three sequential steps or phases:
(1) activation of the APCs; (2) donor T cell activation, proliferation,
differentiation and migration; and (3) target tissue destruction.

Alemtuzumab is a monoclonal antibody that binds CD52, a protein
expressed on a broad spectrum of leukocytes including lymphocytes,
monocytes, and dendritic cells. Its use in GVHD prophylaxis in a
Phase II trial decreased the incidence of acute and chronic GVHD
following reduced intensity transplant.98 In two prospective studies,
patients who received alemtuzumab rather than methotrexate showed
significantly lower rates of acute and chronic GVHD, but experienced
more infectious complications and higher rates of relapse, so that there
was no overall survival benefit. Alemtuzumab may also contribute to
graft failure when used with minimal intensity conditioning regimens.

An alternative strategy to TCD attempted to induce anergy in donor
T cells by ex vivo antibody blockade of co-stimulatory pathways prior
to transplantation. A small study using this approach in haploidentical
HCT recipients was quite encouraging, but has not yet been replicated.
Thus the focus of most prevention strategies remains pharmacological
manipulation of T cells after transplant.

Administration of anti-T cell antibodies in vivo as GVHD prophylaxis
has also been extensively tested. The best studied drugs are anti-
thymocyte globulin (ATG) or antilymphocyte globulin (ALG) preparations.
These sera, which have high titers of polyclonal antibodies, are made
by immunizing animals (horses or rabbits) to thymocytes or lymphocytes,
respectively. A complicating factor in determining the role of these
polyclonal sera in transplantation is the observation that even different
brands of the same class of sera exert different biologic effects. However,
the side effects of ATG/ALG infusions are common across different
preparations and include fever, chills, headache, thrombocytopenia
(from cross-reactivity to platelets), and, infrequently, anaphylaxis. In
retrospective studies, rabbit ATG reduced the incidence of GVHD in
related donor HSCT recipients without appearing to improve survival.
In recipients of unrelated donor HSCT, addition of ALG to standard
GVHD prophylaxis effectively prevented severe GVHD, but did not
result in improved survival because of increased infections. In a long
term follow-up study, however, pretransplant ATG provided significant
protection against extensive chronic GVHD and chronic lung dysfunction.

As allogeneic transplantation becomes an increasingly attractive therapeutic
option, the need for novel approaches to GVHD has accelerated. The
number of patients receiving transplants from unrelated donors is
expected to double in the next five years, significantly increasing
the population of patients with GVHD. The advent of RIC regimens
has reduced transplant-related mortality and lengthened the period
during which acute GVHD may develop (many new cases present up
to day 200) and the need for close monitoring of patients in this period
has increased. Patients have often returned to the care of their primary
hematologists by this time, increasing the need for these physicians to
collaborate with transplant specialists in the management of GVHD and
its complications.

Identification of biomarkers for GVHD with diagnostic (and possibly
prognostic) significance may eventually make the treatment of GVHD
preemptive rather than prophylactic. The use of cellular component therapy,
such as regulatory T cells that have been expanded ex vivo. will also
enter clinical trials in the near future, but the extensive infrastructure
required for such cellular approaches will likely limit their use initially.

Immunomodulatory Effects of Palifermin (Recombinant Human
Keratinocyte Growth Factor) in an SLE-Like Model of Chronic
Graft-Versus-Host Disease

C. A. Ellison, Y. V. Lissitsyn, I. Gheorghiu & J. G. Gartner
Scandinavian Journal of Immunology 2011; 75, 69–76
http://dx.doi.org:/10.1111/j.1365-3083.2011.02628.x

Keratinocyte growth factor (KGF) promotes epithelial cell proliferation
and survival. Recombinant human KGF, also known as palifermin, protects
epithelial cells from injury induced by chemicals, irradiation and acute murine
graft versus-host disease (GVHD). Findings from our studies and others
have shown that palifermin also has immunomodulatory properties. In a
model of acute GVHD, we showed that it shifts the immune response
from one in which Th1 cytokines dominate to mixed Th1 and Th2 cytokine
profile. Using the DBA⁄ 2 fi (C57BL ⁄ 6 · DBA⁄ 2)F1-hybrid model of chronic,
systemic lupus erythematosus-like GVHD, we showed that palifermin
treatment is associated with higher levels of Th2 cytokines, the production
of anti-nuclear antibodies, cryoglobulinemia and the development of more
severe pathological changes in the kidney. The aim of our current study
was to gain a better understanding of the immunobiology of KGF by
further characterizing the palifermin-mediated effects in this model of
chronic GVHD. Because the pathological changes we observed resemble
those seen in thymic stromal lymphopoietin (TSLP) transgenic mice, we
had originally hypothesized that palifermin might augment TSLP levels.
Surprisingly, we did not observe an increase in thymic

TSLP mRNA expression in palifermin-treated recipients. We did, however,
observe some differences in the percentages of CD4+CD25+Foxp3+
regulatory T cells in the spleen at some time points in palifermin-treated
recipients. Most importantly, we found that TGFβ levels were higher in
palifermin-treated recipients early in the GVH reaction, raising the
possibility that KGF might indirectly induce the development of fibrosis
and glomerulonephritis through a pathway involving TGFβ.

Keratinocyte growth factor (KGF) is an epithelial cell growth factor that is
produced by both mesenchymal cells and intraepithelial cdT cells. It is
also known as fibroblast growth factor 7. Its receptor, (KGFR⁄FGF7R), an
alternatively spliced form of FGFR2 ⁄ bek, is found on epithelial cells in
the intestine, mammary glands, ovaries and urinary tract, and on
hepatocytes, keratinocytes and alveolar type II cells. Previously, it
was shown that recombinant human KGF, also known as palifermin,
can protect the lung, bladder or intestine from chemical- or irradiation-
induced injury. This has been attributed to the ability of KGF to reduce
oxidative damage and enhance DNA repair.

Our own studies have provided a better understanding of the immuno-
biological properties of KGF in pathologically distinct models of systemic
disease driven by intense immunological and inflammatory responses.
The acute GVHD that develops in the C57BL ⁄ 6 fi (C57BL ⁄ 6 · DBA⁄ 2)F1-
hybrid model is characterized by the activation of alloreactive donor T cells,
the production of Th1 cytokines and tissue injury in the skin, gastrointestinal
tract, liver, thymus and lung, where epithelia are present. Injury to the
intestinal mucosa permits the translocation of endotoxin into the system,
which, if untreated, leads to the development of endotoxemic shock. We
showed that palifermin treatment protects recipients from epithelial
cell injury, endotoxemia and morbidity in GVH mice. Palifermin also
shifts the immune response away from one that is predominated by Th1
cytokines towards a profile of mixed Th1 and Th2 cytokines, with a
preponderance of Th2 cytokines. The DBA⁄ 2 fi (C57BL ⁄ 6 · DBA⁄ 2)F1-
hybrid model of chronic GVHD is characterized by pathological changes
resembling those seen in systemic lupus erythematosus (SLE). Using this
model, we showed that palifermin treatment augments the production of Th2
cytokines such as IL-4, IL-5 and IL-13 and obviates IFN-c production. Both
untreated and palifermin-treated recipients developed pathological changes
in the kidney, but these changes were more severe in palifermin-treated
recipients. Some of the changes that developed in the palifermin-treated
recipients resemble those seen in thymic stromal lymphopoietin (TSLP)
transgenic mice. These similarities include the presence of ANA in the
sera, the development of cryoglobulinemia and the development of
glomerulonephritis featuring the deposition of immune complexes
consisting of IgG, IgA, IgM and C3 in the mesangium and the glomerular
capillaries. This led us to hypothesize that treating the recipient mice with
palifermin might induce TSLP expression in this model.

In this study, we were interested in determining whether palifermin
treatment was indeed associated with increased TSLP expression.
We were also interested in knowing whether palifermin treatment
changes the percentage of CD4+CD25+FoxP3+ cells in the spleen,
because palifermin treatment has been associated with increased
percentages of CD4+CD25+FoxP3+ cells in other studies including
our own. Lastly, we wished to study the effect of palifermin treatment
on TGFb levels, because this cytokine is known to play a pivotal role
in the development of glomerulonephritis.

We studied the histopathological changes to confirm that the pathological
changes seen in the kidney in this study were the same as those reported
by us previously.We examined kidney sections from both untreated and
palifermin-treated recipients. In these experiments, we were able to
reproduce findings from an earlier study that showed that palifermin-
treated recipients mice in this model of chronic GVHD develop a severe,
extracapillary proliferative glomerular nephritis characterized by epithelial
crescents and hyaline thrombi. These changes were associated with higher
levels of protein in the urine and the development of ascites, presumably
related to the development of nephrotic syndrome, as a consequence
of glomerular injury.

Pathological changes in the kidney. (A) shows a section from a BDF1-hybrid control
mouse that did not receive a graft. (B) shows increased epithelial cellularity within a
glomerulus from an untreated recipient with chronic graft-versus-host disease, on
day 50. No crescents were observed in sections from this group of recipients.
(C and D) show examples of pathological changes observed in kidneys from
palifermin-treated recipients on day 50. Arrows indicate examples of crescentic
glomerulonephritis and the development of protein casts within tubular lumena.
(E and F) show examples of the hyaline thrombi (arrows) seen in the glomeruli
in kidney sections from palifermin-treated recipients on day 50. All sections
were stained with haematoxylin and eosin except for that shown in (F), which
was stained with Masson Trichrome. The concentration of protein measured in
the urine is shown in the lower left corner of each photomicrograph. Original
magnification: ·200 (B–E) and ·400 (A and F).

TGFβ is a highly pleiotropic cytokine with three isoforms, TGFβ1, TGFβ2 and
TGFβ3 . Nearly, all cells have receptors for at least one of these isoforms,
but cells of the immune system primarily express TGFβ1. This cytokine
was implicated in the development of experimental glomerulonephritis in
experiments in which rats were treated with antiserum directed against
TGFβ1. The ability of palifermin to induce TGFβ release and reverse
limited airflow was demonstrated in a mouse model of emphysema. The
authors further showed that palifermin induced the release of TGFβ1
from primary cultures of mouse alveolar type 2 cells. Our results show
that palifermin treatment is associated with a rise in splenic TGFβ levels
during the first month of the GVH reaction. It is possible that by inducing
TGFβ production shortly after transplantation, palifermin treatment is able
to promote the development of the severe, crescentic glomerulonephritis
that we observed at later time points. As such, our findings raise the
possibility that endogenous KGF might play a role in the development
of glomerulonephritis and ⁄ or other autoimmune phenomena associated
with chronic GVHD and ⁄ or SLE.

T cells, murine chronic graft-versus-host disease and autoimmunity

Robert A. Eisenberg, Charles S. Via
Journal of Autoimmunity 39 (2012) 240e247
http://dx.doi.org:/10.1016/j.jaut.2012.05.017

The chronic graft-versus-host disease (cGVHD) in mice is characterized by
the production of autoantibodies and immunopathology characteristic of
systemic lupus erythematosus (lupus). The basic pathogenesis involves
the cognate recognition of foreign MHC class II of host B cells by alloreactive
CD4 T cells from the donor. CD4 T cells of the host are also necessary for
the full maturation of host B cells before the transfer of donor T cells.
CD8 T cells play critical roles as well. Donor CD8 T cells that are highly
cytotoxic can ablate or prevent the lupus syndrome, in part by killing
recipient B cells. Host CD8 T cells can reciprocally downregulate donor
CD8 T cells, and thus prevent them from suppressing the autoimmune
process. Thus, when the donor inoculum contains both CD4 T cells and
CD8 T cells, the resultant syndrome depends on the balance of activities
of these various cell populations. For example, in one cGVHD model
(DBA/2 (C57BL/6xDBA/2)F1, the disease is more severe in females, as
it is in several of the spontaneous mouse models of lupus, as well as in
human disease. The mechanism of this female skewing of disease
appears to depend on the relative inability of CD8 cells of the female host
to downregulate the donor CD4 T cells that drive the autoantibody response.
In general, then, the abnormal CD4 T cell help and the modulating roles
of CD8 T cells seen in cGVHD parallel the participation of T cells in
genetic lupus in mice and human lupus, although these spontaneous
syndromes are presumably not driven by overt alloreactivity.

Systemic lupus erythematosus (SLE) is characterized by a spectrum of auto-
antibodies that targets multiple normal cellular components, particularly
nucleic acids or proteins that are physiologically bound to nucleic acids.
Although SLE is highly diverse in its manifestations, a common theme
is the loss of B cell tolerance to these cellular autoantigens. More than
for any other human condition, several spontaneously arising mouse
models for SLE have been described, beginning with the New Zealand
strains in 1959. These models are largely genetic. In some cases, an
individual gene such as fas or Yaa plays a major role in driving the loss
of tolerance. However, in general the genetic contribution is complex and
involves multiple loci, which are not yet fully defined.

Despite extensive investigations, the failures in immunoregulation that
underlie the genetic SLE models remain poorly understood. It is not known
for sure which B cell tolerance checkpoints are breached in a given model,
and why. The autoantibody response to DNA, Sm, and other autoantigens
resembles the normal response to exogenous antigens: it involves clonal
expansion, somatic mutation, and a pattern of isotype use characteristic of
a T-cell dependent immunization. Thus the cellular dynamics of the response
may be basically normal. Yet the B-cell repertoire is abnormally autoreactive.

In this review we wish to focus more on the role of the T cell in SLE. As
stated above, the loss of B cell tolerance in SLE does appear in general
to require the participation of T cells. Multiple T cells abnormalities have
been described in human and in murine SLE, although in most cases it is
not clear if these are primary or secondary manifestations. Nevertheless,
it is striking how difficult it has been to demonstrate definitively the specificity
of the T cells that provide help for autoantibody production.

The key cellular mechanism in the cGVHD that results in the loss of B cell
tolerance and the production of the autoantibodies typical of SLE is the
cognate interaction of CD4 T cells with an MHC class II determinant on
the B cell surface. A variety of protocols have achieved this interaction.
In general, either the donor/recipient strains are paired in such away
that they only differ at the MHC class II loci, or the CD4 cells are isolated
free of CD8 cells that would recognize MHC class I. If the allorecognition
involves both CD4 T cell interaction with MHC II and CD8 interaction with
MHC I, an acute GVHD occurs, which is immunosuppressive, rather than
immunostimulatory. The DBA/2 (C57BL/6 DBA/2)F1 (B6D2F1) and the
BALB/c (BALB/c A/J)F1 models are exceptions to this rule. The former
has been investigated extensively for a deficiency in CD8 cytotoxic
lymphocytes.

The MHC class II recognition may be at either the I-A or the I-E locus.
However, the autoantibody specificities seen and the degree of immuno-
pathology differ depending on the locus targeted. In one set of experiments,
F1 mice were bred between either B6 or coisogenic bm12 mice and
B10.A(2R) or B10.A(4R) MHC recombinant congenics. The MHC class II
of B6 is I-Ab, while that of bm12 is I-Abm12. These two alleles differ by
only three amino acids, which is sufficient for a full strength MLR (mixed
lymphocyte reaction) between the two strains. Otherwise B6 and bm12
are identical. B10.A(2R) and B10.A(4R) differ only by the expression of
I-E in the former strain, but not in the latter strain. Thus, donor/recipient
combinations could be employed that provided for allogeneic differs only
at I-A, only at I-E, or at both loci.

Results from Busser et al. delineate requirements for this MHC class II
recognition. Utilizing several transgenic mouse strains that express a
more or less constricted CD4 autoreactive repertoire, they showed that
a diverse repertoire was essential to the production of SLE autoantibodies
by MHC II recognition. On the other hand, the non-specific, early polyclonal
B cell activation phase of cGVHD occurred even with a limited CD4 repertoire.

Figure not shown. Chronic GVHD in bm12 C57BL/6 mice. The MHC of the
bm12 donor differs from the MHC of the C57BL/6 recipient just in three
amino acids in the I-A class II molecule. Thus donor CD4 T cells recognize
MHC IIþ B cells as foreign. Donor CD8 T cells see only self MHC I. All T
cells do not express MHC II. Polyclonal activation and specific lupus
autoantibody responses ensue..

Lupus can result from unchecked CD4 T cell cognate help to a polyclonal
population of B cells. CD8 T cells can downregulate this CD4 driven B-cell
hyperactivity through CD8 CTL effectors and can maintain remission,
possibly through memory CD8 T cells. Whether CD8 CTL actually prevent
lupus in normals and fail in lupus prone individuals is not known; however,
data from the P F1 model suggest that therapeutic induction of CD8 CTL
and possibly long term memory cells may be beneficial in preventing or
limiting disease expression. The potential major role played by either
IFNa and IL-21 in both lupus expression and CD8 CTL function remains
to be further defined, but already these cytokines are being targeted in
human or murine lupus.

It is not surprising that the T cells have been shown to have diverse roles in
the autoimmune cGVHD in mice. Donor CD4 T cells drive the host B cell
activation, while host CD4 T cells are required to mature these B cells prior
to their encounter with donor T cells. Donor CD4 T cells also help activate
donor CD8 T cells, which in turn can downregulate or even ablate the
autoimmune response. Donor CD4 T cells license host DC cells, which in
turn can interact with donor CD8 T cells. Host CD8 T cells can suppress
the activity of donor CD8 T cells, and thereby favor the development of
the lupus syndrome. Although the precise mechanisms of T cell participation
in spontaneous lupus are still being defined, it seems reasonable to probe
these syndromes in humans and in mice for T cell mechanism that have
been shown to participate in cGVHD, CD4-B cell interactions almost
certainly are central to the pathogenesis of spontaneous lupus, and they
have been a target of investigation for several decades. If we understood
the peptide specificity of the alloreactive CD4 T cells that drive the formation
of the characteristic lupus autoantibodies, we would have a much clearer
idea where to look for such epitopes in spontaneous disease. Much less
is known about the other T cell activities defined in cGVHD, particularly
those that involve CD8 T cells. This area should invite further detailed
investigation. For example, the striking role of CD8 T cells in the stronger
female disease in the DBA BDF1 model clearly demands that similar
mechanisms be sought for in spontaneous disease.

Understanding Chronic GVHD from Different Angles

Bruce Blazar, Eric S. White, Daniel Couriel
Biol Blood Marrow Transplant 18:S184-S188, 2012
http://dx.doi.org:/10.1016/j.bbmt.2011.10.025

Whereas acute graft-versus-host disease (aGVHD) rates have decreased
with more intensive GVHD preventive agents and use of single and double
umbilical cord blood units as a source of donor cells in adult recipients,
significant chronic GVHD (cGVHD) rates unexpectedly have remained high.
Moreover, granulocyte colony stimulating factor mobilized peripheral blood
stem cell grafts have been associated with an increased overall risk of
cGVHD. As such, cGVHD has emerged as a primary cause of morbidity
and mortality following allogeneic hematopoietic stem cell transplantation.
Progress in developing cGVHD interventional strategies has been hampered
by variable onset and clinical and pathological manifestations of cGVHD, now
better defined by the National Institutes of Health (NIH) consensus conference,
and a dearth of preclinical models that closely mimic the conditions in which
cGVHD is generated and manifested. Although the exact causes of cGVHD
remain unknown, higher antibody levels have been associated with auto-
immunity and implicated in cGVHD. Newly diagnosed patients with
extensive cGVHD had elevated soluble B cell activating factor levels and
anti-double-strand DNA antibodies were found, which was associated with
higher circulating levels of pregerminal center (GC) B cells and post-GC
plasmablasts. B cells from cGVHD patients were hyperresponsive to Toll-like
receptor-9 signaling and have up-regulated CD86 levels.

By using a Cy and low doses of donor T cells, aGVHD was avoided and
cGVHD with BO favored. Histologic changes were similar to the findings in
human cGVHD with peribronchiolar and perivascular cuffing and infiltration
of the airway epithelium. The liver had inflammation and lymphocytic
infiltration, along with collagen deposition. The parotid and submandibular
salivary glands displayed lymphocytic infiltrates in both the bone marrow
and cGVHD groups, likely because of transplantation conditioning.

Treatment of steroid refractory cGVHD patients with rituximab, a B cell–
depleting anti-CD20 monoclonal antibody, has shown a beneficial role in
resolution of the autoimmune disorders such as systemic lupus erythmatosus
and rheumatoid arthritis, andcGVHD, with overall response rates of 29%
to 36% for oral, hepatic, gastrointestinal, and lung cGVHD, and 60% for
cutaneous cGVHD in aggregate data from multiple trials. Thus, we recently
undertook studies to identify the presence of CD41 T helper cells and B2201
B cells in the airways of mice that had BO, tissue-specific antibodies from sera,
and alloantibody deposition in the lung and liver of cGVHD recipients. cGVHD
development was associated with IgG2c deposition in the lung and liver,
abrogated if the donor bone marrow was deficient in mature B cells or
incapable of producing antihost reactive IgG. Robust GC formation was
seen in mice with cGVHD. Alleviation of symptoms in mice that received
B cell–deficient bone marrow confirms the requirement of B cells for lung
dysfunction and inflammation and fibrosis in the lung and liver.

Given a role for IgG antibodies, allo- or auto-Ab binding to the cGVHD organs
could enable tissue destruction or the pathology could be defined by the
specific function of these secreted antibodies. Pathogenic antibody production
therefore is likely to be an important inducer of cGVHD, and targeting this
specific function of the B cells is an attractive strategy for cGVHD. Because
GC B cells display lower susceptibility to rituximab-mediated clearance, probably
because they reside in a nonoptimal environment for antibody-based depletion,
our observation that GC B cells are critical to the development of cGVHD
suggests that agents that are more effective at disrupting the GC might be
more clinically useful. Treatment with LTbR-Ig, a fusion protein that blocks
interactions between LTbR and its ligands, had a direct effect on the
symptoms of cGVHD, at least in part by blocking GC formation and suggest
that LTbR-Ig could be a potential clinical interventional strategy for prevention
and therapy of cGVHD.

Fibrosis is the end result of a number of inflammatory and other injurious events,
resulting in replacement of normal tissue with a dense extracellular matrix (ECM)
scar composed primarily of collagens. While some degree of tissue fibrosis is
considered protective (e.g. in the setting of cutaneous wound healing),
exaggerated or unrelenting ECM deposition with replacement of the normal
tissue architecture is considered pathologic. Fibroproliferative disorders as
a class involving multiple organs (e.g. cGVHD following hematopoietic stem
cell transplant [affecting up to 30% of recipients surviving more than 100 days,
scleroderma [estimated to affect 70,000 in the US], idiopathic pulmonary fibrosis
[estimated to affect 200,000 in the US], hepatic cirrhosis [estimated to affect
up to 400,000 in the US], and renal fibrosis due to diabetic nephropathy and
other causes [estimated to affect over 400,000 in the US]) are a major cause
of morbidity and mortality. Combined, these disorders alone are conservatively
estimated to affect approximately 1 in 300 persons in the United States. When
coupled with a host of other disorders in which tissue fibrosis contributes to
morbidity (e.g. fibroproliferative acute respiratory distress syndrome,
hypersensitivity pneumonitis, solid organ transplant rejection), that estimate
is likely to be much greater.

Wound healing occurs by a highly orchestrated, complex process that has
been well defined. In general, wound repair occurs in 4 stages which overlap
considerably: clotting/coagulation, inflammation, fibroproliferation, and tissue
remodeling. The initial injury leads to a local disruption of epithelial and
endothelial barriers resulting in the elaboration of inflammatory mediators and
extravasation of cells and plasma proteins that serve to achieve hemostasis
and provide a provisional fibrin-rich matrix for the influx of inflammatory and
other reparative cells. Simultaneously, platelet degranulation provides a local
“boost” of vasodilators, growth factors, and ECM proteins that aid in the wound
healing response. Inflammatory cell influx occurs next, with polymorphonuclear
leukocytes (PMNs) arriving first. Following PMN degranulation, mononuclear
cells (macrophages and lymphocytes) arrive next and, along with PMN derived
products, sterilize and remove foreign materials from the wound. This process
also results in the elaboration of cytokines and chemokines designed to
augment the inflammatory response, to promote angiogenesis (allowing for
enhanced nutrient and oxygen delivery to the wound bed), and to recruit
fibroblasts to the wound bed. Fibroblast recruitment and transdifferentiation to
myofibroblasts (or recruitment of already-differentiated myofibroblasts or
fibroblast precursors; this point is still controversial) marks the fibroproliferative
stage, with the result being the elaboration of ECM proteins (collagens,
fibronectins) to repair the tissue defect.

Vorinostat plus tacrolimus and mycophenolate to prevent graft-versus-host
disease after related-donor reduced-intensity conditioning allogeneic
hemopoietic stem-cell transplantation: a phase 1/2 trial

Sung Won Choi, T Braun, L Chang, JLM Ferrara, A Pawarode, et al.
Lancet Oncol 2014; 15: 87–95
http://dx.doi.org/10.1016/S1470-2045(13)70512-6

Background Acute graft-versus-host disease (GVHD) remains a barrier to more
widespread application of allogeneic hemopoietic stem-cell transplantation.
Vorinostat is an inhibitor of histone deacetylases and was shown to attenuate
GVHD in preclinical models. We aimed to study the safety and activity of
vorinostat, in combination with standard immunoprophylaxis, for prevention of
GVHD in patients undergoing related-donor reduced-intensity conditioning
hemopoietic stem-cell transplantation. Methods Between March 31, 2009,
and Feb 8, 2013, we did a prospective, single-arm, phase 1/2 study at two
centers in the USA. We recruited adults (aged ≥18 years) with high-risk
hematological malignant diseases who were candidates for reduced-intensity
conditioning hemopoietic stem-cell transplantation and had an available 8/8
or 7/8 HLA matched related donor. All patients received a conditioning regimen
of fl udarabine (40 mg/m² daily for 4 days) and busulfan (3·2 mg/kg daily for
2 days) and GVHD immunoprophylaxis of mycophenolate mofetil (1 g three
times a day, days 0–28) and tacrolimus (0·03 mg/kg a day, titrated to a goal
level of 8–12 ng/mL, starting day –3 until day 180). Vorinostat (either 100 mg
or 200 mg, twice a day) was initiated 10 days before haemopoietic stem-cell
transplantation until day 100. The primary endpoint was the cumulative
incidence of grade 2–4 acute GVHD by day 100. This trial is registered with
ClinicalTrials.gov, number NCT00810602.
Findings 50 patients were assessable for both toxic effects and response;
eight additional patients were included in the analysis of toxic effects. All
patients engrafted neutrophils and platelets at expected times after
hemopoietic stem-cell transplantation. The cumulative incidence of grade
2–4 acute GVHD by day 100 was 22% (95% CI 13–36). The most common
non-hematological adverse events included electrolyte disturbances (n=15),
hyperglycemia (11), infections (six), mucositis (four), and increased activity
of liver enzymes (three). Non-symptomatic thrombocytopenia after
engraftment was the most common hematological grade 3–4 adverse
event (nine) but was transient and all cases resolved swiftly.
Interpretation Administration of vorinostat in combination with standard
GVHD prophylaxis after related-donor reduced-intensity conditioning
hemopoietic stem-cell transplantation is safe and is associated with a
lower than expected incidence of severe acute GVHD. Future studies
are needed to assess the effect of vorinostat for prevention of GVHD in
broader settings of hemopoietic stem-cell transplantation.

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Allogeneic Transfusion Reactions

Posted in Coagulation Therapy and Internal Bleeding, Hematology, Hematopoiesis, Human Immune System in Health and in Disease, Immuno-Oncology & Genomics, Immunodiagnostics on February 18, 2015| Leave a Comment »

Allogeneic Transfusion Reactions

Writer and Curator: Larry H. Bernstein, MD, FCAP

Introduction

Transfusion Medicine owes much to the discovery of the ABO Blood Groups
by Landsteiner. This was a landmark in the history of immunology.  The next
important discovery was the RhD system in immune hemolytic anemia of the
newborn, which was important in the history of neonatology.  As blood banking
became critical in the preparation, storage, transport, and transfusion of blood
during the Second World War, there was the elucidation of the Kell, MNSs,
Kidd, Duffy, Lewis, and other red cell antigenic systems.  The type and screen
for antibodies, and for red cell compatibility in the crossmatch became routine,
and a formal classification of the antigenic components was created.
Incompatibilities in transfusion mediated reactions were expressed as
allogeneic transfusion reactions.  The red cell was not the only component,
as whole blood was ultimately broken into red cell units, plasma, and platelets,
and eventually a neutrophilic component.  With the development of solid organ
transplantation, the definition of the HLA antigen was a large focus for
compatibility.  Today, the traditional problems of transfusion immuno-compatibility have become displaced in large measure by transplantation
issues.  This piece and that which follows will address allogeneic
transplantation reactions and graft-versus-host disease.

Blood Groups

Although all blood is made of the same basic elements, not all blood is
alike. In fact, there are eight different common blood types, which are
determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign
to the body. Since some antigens can trigger a patient’s immune system
to attack the transfused blood, safe blood transfusions depend on careful
blood typing and cross-matching.

There are four major blood groups determined by the presence or absence
of two antigens – A and B – on the surface of red blood cells:

Group A – has only the A antigen on red cells (and B antibody in the plasma)
Group B – has only the B antigen on red cells (and A antibody in the plasma)
Group AB – has both A and B antigens on red cells (but neither A nor B
antibody in the plasma)
Group O – has neither A nor B antigens on red cells (but both A and B
antibody are in the plasma)

There are very specific ways in which blood types must be matched for a
safe transfusion. See the chart below:

http://www.redcrossblood.org/sites/arc/files/images/ab_top.gif

In addition to the A and B antigens, there is a third antigen called the
Rh factor, which can be either present (+) or absent ( – ). In general,
Rh negative blood is given to Rh-negative patients, and Rh positive blood
or Rh negative blood may be given to Rh positive patients.

O positive is the most common blood type. Not all ethnic groups have the
same mix of these blood types. Hispanic people, for example, have a relatively
high number of O’s, while Asian people have a relatively high number of B’s.
The mix of the different blood types in the U.S. population is:

	Caucasians	African American	Hispanic	Asian
O +	37%	47%	53%	39%
O –	8%	4%	4%	1%
A +	33%	24%	29%	27%
A –	7%	2%	2%	0.5%
B +	9%	18%	9%	25%
B –	2%	1%	1%	0.4%
AB +	3%	4%	2%	7%
AB –	1%	0.3%	0.2%	0.1%

Some patients require a closer blood match than that provided by the ABO
positive/negative blood typing. For example, sometimes if the donor and
recipient are from the same ethnic background the chance of a reaction
can be reduced. That’s why an African-American blood donation may be
the best hope for the needs of patients with sickle cell disease, 98 percent
of whom are of African-American descent.

http://www.redcrossblood.org/learn-about-blood/blood-types

Whether your blood group is type A, B, AB or O is based on the blood types
of your mother and father.

This chart shows the potential blood types you may inherit.

Parent 1

Parent 2

Possible
blood
type
of
child

A blood type (also called a blood group) is a classification of blood based on
the presence or absence of inherited antigenic substances on the surface of
red blood cells (RBCs). These antigens may be proteins, carbohydrates,
glycoproteins, or glycolipids, depending on the blood group system. Some of
these antigens are also present on the surface of other types of cells of
various tissues. Several of these red blood cell surface antigens can stem
from one allele (or very closely linked genes) and collectively form a blood
group system. Blood types are inherited and represent contributions from
both parents. A total of 33 human blood group systems are now recognized
by the International Society of Blood Transfusion (ISBT). The two most
important ones are ABO and the RhD antigen; they determine someone’s
blood type (A, B, AB and O, with +, − or Null denoting RhD status).

Many pregnant women carry a fetus with a blood type which is different from
their own, and the mother can form antibodies against fetal RBCs. Sometimes
these maternal antibodies are IgG, a small immunoglobulin, which can cross
the placenta and cause hemolysis of fetal RBCs, which in turn can lead to
hemolytic disease of the newborn called erythroblastosis fetalis, an illness
of low fetal blood counts that ranges from mild to severe. Sometimes this is
lethal for the fetus; in these cases it is called hydrops fetalis.

ABO_blood_type.svg

http://upload.wikimedia.org/wikipedia/commons/thumb/3/32/ABO_blood_type.svg/824px-ABO_blood_type.svg.png

Blood type (or blood group) is determined, in part, by the ABO blood group antigens

A complete blood type would describe a full set of 30 substances on the surface
of RBCs, and an individual’s blood type is one of many possible combinations
of blood-group antigens. Across the 33 blood groups, over 600 different blood-
group antigens have been found, but many of these are very rare, some being
found mainly in certain ethnic groups.

Almost always, an individual has the same blood group for life, but very rarely
an individual’s blood type changes through addition or suppression of an
antigen in infection, malignancy, or autoimmune disease. Another more
common cause in blood type change is a bone marrow transplant. Bone-marrow transplants are performed for many leukemias and lymphomas,
among other diseases. If a person receives bone marrow from someone
who is a different ABO type (e.g., a type A patient receives a type O bone
marrow), the patient’s blood type will eventually convert to the donor’s type.

Some blood types are associated with inheritance of other diseases; for example,
the Kell antigen is sometimes associated with McLeod syndrome. Certain
blood types may affect susceptibility to infections, an example being the
resistance to specific malaria species seen in individuals lacking the Duffy
antigen. The Duffy antigen, presumably as a result of natural selection, is
less common in ethnic groups from areas with a high incidence of malaria.

The Rh system (Rh meaning Rhesus) is the second most significant blood-
group system in human-blood transfusion with currently 50 antigens.
The most significant Rh antigen is the D antigen, because it is the most
likely to provoke an immune system response of the five main Rh antigens.
It is common for D-negative individuals not to have any anti-D IgG or
IgM antibodies, because anti-D antibodies are not usually produced
by sensitization against environmental substances. However, D-negative
individuals can produce IgG anti-D antibodies following a sensitizing event:
possibly a fetomaternal transfusion of blood from a fetus in pregnancy or
occasionally a blood transfusion with D positive RBCs. Rh disease can
develop in these cases. Rh negative blood types are much less common
in proportion of Asian populations (0.3%) than they are in White (15%).
The presence or absence of the Rh antigens is signified by the + or − sign,
so that for example the A− group does not have any of the Rh antigens.

http://en.wikipedia.org/wiki/Blood_type

Allogeneic blood transfusions: benefit, risks and clinical indications
in countries with a low or high human development index

Carlos Marcucci, Caveh Madjdpour and Donat R. Spahn
Br Med Bull (2004) 70 (1): 15-28. http://dx.doi.org:/10.1093/bmb/ldh023

The risks associated with allogeneic red blood cell (RBC) transfusions differ
significantly between countries with low and high human development indexes
(HDIs). In countries with a low HDI, the risk of infection (HIV, HBV, HCV and
malaria) is elevated. In contrast, in countries with a high HDI, immunological
reactions (hemolytic transfusion reactions, alloimmunization and immuno-suppression) are predominant. Therefore the overall risk associated with RBC
transfusions in low HDI countries is much more significant than that in high HDI
countries. In view of these risks, the limited efficacy of RBC transfusion and its
high costs, this procedure should be used sparingly and rationally.

Red blood cell (RBC) transfusions originating from an unrelated donor are known
as allogeneic RBC transfusions. In the West, i.e. in countries with a high human
development index (HDI), which is an index based on life expectancy, literacy,
enrolment in further education and per capita income, >50% of RBC transfusions
are used in trauma and surgery to compensate for major blood loss.

RBC transfusions are certainly beneficial in specific situations, but are accompanied
by many risks and side effects. Several recent studies have suggested that RBC
transfusions are associated with major adverse outcomes and high costs. In addition,
RBC transfusions are a limited resource and blood shortages can occur at times.

The risk of viral transmission via RBC transfusions has decreased considerably
in recent years in high HDI countries, although new transfusion-transmitted
viruses have been discovered.14 In contrast, in countries with medium or low
HDIs, the risk of transmission of infectious diseases may still be extremely high.

Most reviews consider risks on transfusion-transmissible infections and
immunological reactions, associated with RBC transfusions, that are only
applicable to Western countries, i.e. countries with a high HDI. Although 83%
of the global population live in countries with medium and low HDIs, they
have access to only 40% of the global blood supply. Most notably, all blood
donations in high HDI countries are screened for transfusion-transmissible
infections, whereas only 57% of blood donations in medium and low HDI
countries are tested. In addition, the tests used for blood screening are
not always comparable. For example, only four of the 19 countries
participating in the ‘Workshop of the Directors of National Blood Transfusion
Services’, held in Harare, Zimbabwe, in 2000, used p24 antigen testing for
HIV blood screening.18 Moreover, the blood donation rate per 1000 population
is almost 20 times higher in developed countries than in countries with a low HDI.
Regular non-remunerated volunteers, who are the safest donors, provide 98%
of donations in high HDI countries. In contrast, such donors are a minority in
low HDI countries where up to 60% of donated blood comes from relatives of
the anemic patient or from paid donors.

Acute extravascular hemolytic transfusion reaction due to
anti-Kpa antibody missed by electronic crossmatch

Ruth Padmore, Philip Berardi, …, Doris Neurath, Elianna Saidenberg
Transfusion and Apheresis Science 51 (2014) 168–171
http://dx.doi.org/10.1016/j.transci.2014.08.011

Background: Kpa antigen is a low incidence red blood cell antigen within the Kell
system. Anti-Kpa alloantibody may be associated with acute and delayed hemolytic
transfusion reactions.
Case Study: We report a case of a clinically significant acute extravascular
hemolytic transfusion reaction mediated by previously unrecognized (and
undetected) anti-Kpa alloantibody. This reaction occurred in a patient who
met all criteria for electronic crossmatch, resulting in the transfusion of an
incompatible red cell unit.
Results: Post-transfusion investigation showed the transfused red cell unit
was crossmatch compatible at the immediate spin phase but was 3 + incompatible
at the antiglobulin phase.No evidence of intravascular hemolysis was observed
upon visual comparison of the pre and post-transfusion peripheral blood plasma.
Further testing showed the presence of anti-Kpa antibody. The clinical course
of the patient included acute febrile and systemic reaction.
Conclusion: Acute extravascular hemolytic transfusion reaction may occur due
to undetected anti-Kpa alloantibody. Various strategies for crossmatching are
discussed in the context of antibodies to low incidence antigens.

Transfusion-related mortality: the ongoing risks of allogeneic blood
transfusion and the available strategies for their prevention

Eleftherios C. Vamvakas and Morris A. Blajchman
Blood. 2009; 113: 3406-3417
http://dx.doi.org:/10.1182/blood-2008-10-167643

As the risks of allogeneic blood transfusion (ABT)–transmitted viruses were
reduced to exceedingly low levels in the US, transfusion-related acute lung injury
(TRALI), hemolytic transfusion reactions (HTRs), and transfusion-associated
sepsis (TAS) emerged as the leading causes of ABT related deaths. Since 2004,
preventive measures for TRALI and TAS have been implemented, but their
implementation remains incomplete. Infectious causes of ABT-related deaths
currently account for less than 15% of all transfusion-related mortality, but the
possibility remains that a new transfusion-transmitted agent causing a fatal
infectious disease may emerge in the future. Aside from these established
complications of ABT, randomized controlled trials comparing recipients of
non–white blood cell (WBC)–reduced versus WBC-reduced blood components
in cardiac surgery have documented increased mortality in association with
the use of non-WBC–reduced ABT. ABT-related mortality can thus be further
reduced by universally applying the policies of avoiding prospective donors
alloimmunized to WBC antigens from donating plasma products, adopting
strategies to prevent HTRs, WBC-reducing components transfused to patients
undergoing cardiac surgery, reducing exposure to allogeneic donors through
conservative transfusion guidelines and avoidance of product pooling, and
implementing pathogen-reduction technologies to address the residual risk of TAS as well as the potential risk of a transfusion transmitted agent to emerge
in the foreseeable future.

Red blood cell-incompatible allogeneic hematopoietic progenitor cell
transplantation

S D Rowley, M L Donato and P Bhattacharyya
Bone Marrow Transplantation (2011) 46, 1167–1185; http://dx.doi.org:/10.1038/bmt.2011.135

Transplantation of hematopoietic progenitor cells from red cell-incompatible
donors occurs in 30–50% of patients. Immediate and delayed hemolytic
transfusion reactions are expected complications of red cell-disparate
transplantation and both ABO and other red cell systems such as Kidd
and rhesus can be involved. The immunohematological consequences of
red cell-incompatible transplantation include delayed red blood cell recovery,
pure red cell aplasia and delayed hemolysis from viable lymphocytes carried
in the graft (‘passenger lymphocytes’). The risks of these reactions, which
may be abrupt in onset and fatal, are ameliorated by graft processing and
proper blood component support. Red blood cell antigens are expressed on
endothelial and epithelial tissues in the body and could serve to increase
the risk of GvHD. Mouse models indicate that blood cell antigens may
function as minor histocompatibility antigens affecting engraftment. Similar
observations have been found in early studies of human transplantation
for transfused recipients, although current conditioning and immuno-suppressive regimens appear to overcome this affect. No deleterious effects
from the use of red cell-incompatible hematopoietic grafts on transplant
outcomes, such as granulocyte and platelet engraftments, the incidences
of acute or chronic GvHD, relapse risk or OS, have been consistently
demonstrated. Most studies, however, include limited number of patients,
varying diagnoses and differing treatment regimens, complicating the
detection of an effect of ABO-incompatible transplantation. Classification
of patients by ABO phenotype ignoring the allelic differences of these
antigens also may obscure the effect of red cell-incompatible transplantation
on transplant outcomes.

Severe hemolytic transfusion reaction due to anti-A1 following allogeneic
stem cell transplantation with minor ABO incompatibility

Çiğdem Akalın Akkok, Håkon Haugaa, Anders Galgerud, Lorentz Brinch
Transfusion and Apheresis Science 2013; 48(1), Pages 63–66
http://dx.doi.org/10.1016/j.transci.2012.07.006

Blood components should be compatible both with the recipient and the
donor in the ABO incompatible allogeneic stem cell transplantation setting.
A patient with blood type A2 received peripheral blood stem cells from a
blood type O donor. The patient was in critical condition due to treatment-
related toxicity. He had acquired anti-A1 that was unfortunately overlooked.
Following transfusion of A1 red blood cells in error, he developed a severe
hemolytic transfusion reaction. Anti-A1 is rarely clinically significant.
We discuss the role of passenger lymphocytes in development of the anti-A1, and stress the importance of investigating unusual/atypical reactions
in blood typing.

Transfusion Support of Allogeneic Stem Cell Transplant Recipients

Kate Chipperfield MD FRCPC 21 Feb 2012

After this session, the learner will be able to:

Provide an overview of transfusion issues in allogeneic stem cell transplant.
Discuss the potential consequences of ABO mismatch between recipient
and donor.
Understand the rationale for ABO/D group selection of blood product support
peri-stem cell transplant.
Appreciate the special impact of umbilical cord blood stem cell transplant.
Briefly outline variable practices in transfusion support of stem cell
transplantation.

Pre-transplant

Leukocyte Reduction

– reduction in HLA Alloimmunization (TRAP study)

– reduction in CMV infection in seronegative candidates*

Avoidance of directed donations
Irradiation of cellular blood products

– Only from start of SCT conditioning (to end of GVHD prophylaxis or
lymphs >1 x 109/L)

Issues with this

– as soon as identified as potential SCT recipient*

– prevention of microchimerism in intended recipient (donor lymphocytes)

ABO and SCT

Any allogeneic SCT will be one of:

– ABO-Identical

– Major ABO Incompatible

– Minor ABO Incompatible

– Major and Minor incompatible (Bidirectional)

(more not shown)

Major ABO Blood Group Mismatch Increases the Risk for Graft Failure
after Unrelated Donor Hematopoietic Stem Cell Transplantation

Mats Remberger, E Watz, O Ringdén, J Mattsson, A Shanwell, A Wikman
Biology of Blood and Marrow Transplantation 13:675-682 (2007)
http://dx.doi.org:/10.1016/j.bbmt.2007.01.084

Two hundred twenty-four patients with leukemia transplanted with an unrelated
donor between 1991 and 2003 at the Karolinska University Hospital were
analyzed according to association between graft failure and ABO, RhD, MNSs,
and Kidd blood group antigen compatibility. Median age was 29 years
(range: 0-55). Conditioning consisted of total-body irridiation or busulfan-based myeloablative conditioning. A bone marrow graft was given to 152
patients, and 72 patients received peripheral blood stem cells. Most patients
received graft-versus-host disease prophylaxis with cyclosporine and MTX.
Graft failure (GF) was seen in 6 (2.7%) patients. In the multivariate analysis
major ABO mismatch (odds ratio [OR] 14.9, 95% confidence interval
[CI] 2.01-110, P = .008) and HLA-allele mismatch (6.42, 1.19-34.8, P = .03)
was significantly associated to GF. In patients with and without major ABO
mismatch the incidence of GF was 7.5% and 0.6% (P = .02), respectively.
Using an ABO major mismatched graft increases the risk for GF after
unrelated donor hematopoietic stem cell transplantation.

Perioperative transfusion-related acute lung injury: The Canadian
Blood Services experience

Asim Alam, Mary Huang, Qi-Long Yi, Yulia Lin, Barbara Hannach
Transfusion and Apheresis Science 50 (2014) 392–398
http://dx.doi.org/10.1016/j.transci.2014.04.008

Purpose: Transfusion-related acute lung injury (TRALI) is a devastating transfusion-associated adverse event. There is a paucity of data on the incidence and
characteristics of TRALI cases that occur perioperatively. We classified
suspected perioperative TRALI cases reported to Canadian Blood Services
between 2001 and 2012, and compared them to non-perioperative cases
to elucidate factors that may be associated with an increased risk of developing
TRALI in the perioperative setting. Methods: All suspected TRALI cases
reported to Canadian Blood Services (CBS) since 2001 were reviewed by
two experts or, from 2006 to 2012, the CBS TRALI Medical Review Group
(TMRG). These cases were classified based on the Canadian Consensus
Conference (CCC) definitions and detailed in a database. Two additional
reviewers further categorized them as occurring within 72 h from the onset of
surgery (perioperative) or not in that period (non-perioperative). Various
demographic and characteristic variables of each case were collected and
compared between groups. Results: Between 2001 and 2012, a total of
469 suspected TRALI cases were reported to Canadian Blood Services;
303 were determined to be within the TRALI diagnosis spectrum. Of those,
112 (38%) were identified as occurring during the perioperative period.
Patients who underwent cardiac surgery requiring cardiopulmonary bypass
(25.0%), general surgery (18.0%) and orthopedics patients (12.5%) represented
the three largest surgical groups. Perioperative TRALI cases comprised more
men (53.6% vs. 41.4%, p = 0.04) than non-perioperative patients. Perioperative
TRALI patients more often required supplemental O2 (14.3% vs. 3.1%, p = 0.0003),
mechanical ventilation (18.8% vs. 3.1%), or were in the ICU (14.3% vs. 3.7%,
p = 0.0043) prior to the onset of TRALI compared to non-perioperative TRALI
patients. The surgical patients were transfused on average more components
than non-perioperative patients (6.0 [SD = 8.3] vs. 3.6 [5.2] products per patient,
p = 0.0002). Perioperative TRALI patients were transfused more plasma (152
vs. 105, p = 0.013) and cryoprecipitate (51 vs. 23, p < 0.01) than nonperioperative
TRALI patients. There was no difference between donor antibody test results
between the groups. Conclusion: CBS data has provided insight into the
nature of TRALI cases that occur perioperatively; this group represents a
large proportion of TRALI cases.

Platelet allo-antibodies identification strategies forpreventing and
managing platelet refractoriness

Basire, C.Picard
Transfusion Clinique et Biologique 21(2014)193–206
http://dx.doi.org/10.1016/j.tracli.2014.08.140

Platelet refractoriness is a serious complication for patients receiving recurrent
platelet transfusions ,which can be explained by non-immune and immune causes.
Human Leukocyte Antigens (HLA) allo-immunization, especially against HLA
class I, is the major cause for immune platelet refractoriness. To a lesser extent,
alloantibodies against specific Human Platelet Antigen (HPA) are also involved.
Pregnancy, transplantation and previous transfusions can lead to allo-immune reaction against platelet antigens. After transfusion, platelet count
is decreased by accelerated platelet destruction related to antibodies
fixation on incompatible platelet antigens. New laboratory tests for allo-antibodies identification were developed to improve sensibility and specificity,
especially with the LUMINEX® technology. The good use and interpretation
of these antibodies assays can improve strategies for platelet refractoriness
prevention and management with a patient adapted response. Compatible
platelets units can be selected according to their identity with recipient
typing or immune compatibility regarding HLA or HPA antibodies or HLA
epitope compatibility. Prospective studies are needed to further confirm the
clinical benefit of new allo-antibodies identification methods and consensus
strategies for immune platelet refractoriness management.

For Anti-HLA-Specific Donor Antibodies Detection By Flow Cytometry
Cytotoxic Crossmatches Comparison of Methods

Cervelli, F. Pisani, A. Aureli, R. Azzarone, .., A. Famulari, and F. Papola Transplantation Proceedings, 45, 2761e2764 (2013)
http://dx.doi.org/10.1016/j.transproceed.2013.07.023

Anti-HLA-specific donor antibodies induce rapid, irreversible destruction of
the transplant (hyperacute rejection) that today happens rarely due to
immunologic studies prospective crossmatch of patients awaiting the kidney
graft. The usual approach for pretransplant donor/recipient evaluation is
based on 2 methods: (1) the cytotoxic complement crossmatch (CDC) and
(2) the flow cytometric crossmatch  (FCX). The CDC crossmatch is positive
when complement-fixing antibodies are present, an absolute contra-
indication to kidney transplantation. The more sensitive FCX-positive
crossmatch detects low concentrations of unable to fix performed
antibodies complement. It is an  “index” of possible damage due to
accelerated rejection. The target of our study was to develop a cytotoxic
flow cytometry crossmatch (cFCX) that detected cytotoxic antibodies
move sensitively  than the traditional CDC method and also was less
subjective and more standardized for interpretation studying sera from
23 patients; the cFCX showed the requested efficiency characteristics even
in an emergency. In addition, the new method permitted one to calculate a
cutoff for positivity (average value of the negative control at + 2 standard
deviations), assuring an “objective” interpretation of the results that agreed
with the CDC but was more sensitive and accurate allowing solution of
ambiguous results for cases of “doubt”-positive CDC crossmatch.
Furthermore, our aim was to correlate the effect of the strength of the anti-HLA
antibodies determined by mean fluorescence intensity value of LabScreen
Single Antigen beads with results of CDC, cFCX, and FCX methods.

Allogeneic Stem Cell Transplants and Associated Incompatibities

Analysis of Donor and Recipient ABO Incompatibility and Antibody-
Associated Complications after Allogeneic Stem Cell Transplantation
with Reduced-Intensity Conditioning

Emma Watz, Mats Remberger, Olle Ringden, Joachim Lundahl, et al.
Biol Blood Marrow Transplant 20 (2014) 264e271
http://dx.doi.org/10.1016/j.bbmt.2013.11.011

Allogeneic hematopoietic stem cell transplantation (HSCT) can be performed
across the ABO blood group barrier. The impact of ABO incompatibility on
clinical outcome is controversial. A retrospective analysis of 310 patients who
underwent HSCT with reduced-intensity conditioning between 1998 and 2011
was performed to investigate the frequency and clinical implications of anti-RBC
antibodies in passenger lymphocyte syndrome (PLS) after minor ABO mismatch
(mm), persistent or recurring recipient type ABO antibodies (PRABO) after major
ABO mm HSCT, and autoimmune hemolytic anemia (AIHA). Transplantation
characteristics and clinical outcome were analyzed by univariate and multivariate
analysis for groups with or without anti-RBC antibodies. ABO blood group
incompatibility did not affect clinical outcome despite an increased requirement
of blood transfusion. Twelve patients with AIHA, 6 patients with PLS, and 12
patients with PRABO post-HSCT were identified. AIHA did not affect overall
survival (OS) or transplant-related mortality (TRM), but patients with AIHA had
a lower incidence of grades II to IV acute graft-versus-host disease (P < .05).
OS in the PLS group was 0% compared with 61% in the whole group receiving
minor ABO mm transplants (P < .001). Comparing PRABO patients with those
receiving a major ABO mm HSCT, the OS was 17% versus 73% (P <.002) and
TRM was 50% versus 21% (P < .03). At our center, PLS after minor ABO mm
and PRABO antibodies after major ABO mm HSCT are significant risk factors
for decreased OS and TRM. Our results suggest that occurrence of unexpected
ABO antibodies after HSCT warrant a wider investigation individual to find the
underlying cause.

Current Trends in Clinical Studies of Allogeneic Hematopoietic Stem Cell
Transplantation

Sophie Pilon, D Jedrysiak, D Sheppard, CN Bredeson, J Tay, DS Allan
Biol Blood Marrow Transplant 21 (2015) 364e381
http://dx.doi.org/10.1016/j.bbmt.2014.09.014

Allogeneic hematopoietic stem cell transplantation (HSCT) is a specialized
intervention performed at select centers worldwide. The extent to which
specific aspects of care in allogeneic HSCT have been studied and the
types of studies performed for different aspects of care remains incompletely
documented. Studies in allogeneic HSCT were systematically identified from
selected high-profile transplant journals between July 2010 and June 2011
and previously reported in a study addressing the definition of clinical outcomes
in HSCT. All articles were retrieved and assessed for study characteristics and
categorized by specific aspects of care related to allogeneic HSCT. One
hundred sixteen articles were retrieved and reviewed in detail by investigators.
The most studied aspect of care was conditioning regimens. Transfusion
practices were the most understudied aspect of care. Interestingly, most
studies included both adult and pediatric patients. Studies involving all
hematological malignancies were encountered more often than disease-
specific studies. Geographically, most patients described in the published reports
were treated only in North America or only in Europe. Most studies were
retrospective (78), and 25 reported on multicenter registry data. Of the 38
prospective studies, 8 were randomized controlled trials (RCTs) and
predominantly focused on prevention and treatment of graft-versus-host disease
(GVHD) and infections. Median follow-up was longer in retrospective registry
studies (54 months) and shortest in RCTs (32 months). The proportion of
positive outcomes in retrospective and prospective studies was remarkably
high (>80% for all categories) and not significantly different across all aspects
of care (P > .05). When comparing RCTs and registry data studies, this proportion
was similar and high (95% and 100%, respectively, P >.05). Our study highlights
the established and important role of retrospective registry studies for many
aspects of care and suggests RCTs may be most relevant for studies on
infectious complications and GVHD.

Efficacy and Long-Term Outcome of Treatment for Pure Red Cell Aplasia
after Allogeneic Stem Cell Transplantation from Major ABO-Incompatible
Donors

Makoto Hirokawa, T Fukuda, K Ohashi, …, H Sakamaki, for The PRCA
Collaborative Study Group
Biol Blood Marrow Transplant 19 (2013) 1026e1032
http://dx.doi.org/10.1016/j.bbmt.2013.04.004

No standard of care for pure red cell aplasia (PRCA) after major ABO-
incompatible hematopoietic stem cell transplantation (HSCT) has been
established. We conducted a retrospective cohort study to learn the
efficacy and outcome of treatment for PRCA. One hundred forty-five
recipients who showed delayed recovery of erythropoiesis and survived
>100 days after transplantation without early disease progression were
selected from 2846 records of major ABO-incompatible transplantation
in the registry database in Japan, and detailed data of 46 recipients
were collected. Treatment of PRCA, such as rapid tapering of calcineurin
inhibitors, corticosteroids, or additional immunosuppressants, was given
to 22 patients but not to the other 24 patients. The overall response rate
of the treatment group was 54.5%. The number of days from diagnosis of
PRCA to recovery of reticulocytes >1% and the cumulative number of red
blood cell transfusions were not significantly different between the 2 groups.
Infections accounted for the death of 7 of 11 patients in the treatment group.
Univariate analysis identified 5 variables influencing survival, including graft-
versus-host disease, disease progression, and treatment of PRCA; disease
progression remained as the only factor negatively affecting survival by
multivariate analysis. The present study could not provide supportive
evidence for the beneficial effects of treatment for PRCA after major
ABO-mismatched HSCT.

Current therapy of myelodysplastic syndromes

Amer M. Zeidan, Yuliya Linhares, Steven D. Gore
Blood Reviews 27 (2013) 243–259
http://dx.doi.org/10.1016/j.blre.2013.07.003

After being a neglected and poorly-understood disorder for many years, there
has been a recent explosion of data regarding the complex pathogenesis of
myelodysplastic syndromes (MDS). On the therapeutic front, the approval of
azacitidine, decitabine, and lenalidomide in the last decade was a major
breakthrough. Nonetheless, the responses to these agents are limited and
most patients progress within 2 years. Allogeneic stem cell transplantation
remains the only potentially curative therapy, but it is associated with significant
toxicity and limited efficacy. Lack or loss of response after standard therapies
is associated with dismal outcomes. Many unanswered questions remain
regarding the optimal use of current therapies including patient selection,
response prediction, therapy sequencing and combinations, and management
of resistance. It is hoped that the improved understanding of the underpinnings
of the complex mechanisms of pathogenesis will be translated into novel
therapeutic approaches and better prognostic/predictive tools that would
facilitate accurate risk-adaptive therapy.

Donor Selection for Killer Immunoglobulin-like Receptors B Haplotype
of the Centromeric Motifs Can Improve the Outcome after HLA-Identical
Sibling Hematopoietic Stem Cell Transplantation

Huifen Zhou, Xiaojing Bao, …, Miao Wang, Depei Wu, Jun He
Biol Blood Marrow Transplant 20 (2014) 98e105
http://dx.doi.org/10.1016/j.bbmt.2013.10.017

After hematopoietic stem cell transplantation (HSCT), natural killer (NK) cell
alloreactivity in HLA cells of recipients is regulated by killer immunoglobulin-like
receptors (KIRs) on donor NK cells. The effect of KIRs on HSCT outcomes
is controversial, particularly in those undergoing HLA-identical sibling HSCT.
In this study, effects of KIR and HLA genotypes on the HSCT outcome were
investigated in a 5-year retrospective study comprising 219 patient-donor pairs
undergoing HLA-identical sibling HSCT for myeloid and lymphoid malignancies.
We found that 39.7% (87 of 219) of these pairs, which were KIR mismatched,
had better overall survival (OS) and reduced grade III to IV acute graft-versus-
host disease (aGVHD), especially in acute myeloid leukemia (AML) patients.
Bx1 donor KIR genotype with haplotype B on a telomeric region was a risk
factor for the OS and relapse-free survival (RFS). Donor centromeric (c) and
telomeric (t) KIR haplotype analysis showed that donor KIR cB-tA/tB was
associated with improved OS and RFS compared with cA-tA or cA-tB.
Furthermore, donor KIR B haplotype of the centromeric motifs (Cen-B) was
an independent beneficial factor in improving OS and RFS and in protecting
from relapse after HSCT. In AML patients, the occurrence of a GVHD was
significantly lower in HLA-C1 group compared with that in HLA-C2 group,
although such effect was not observed in patients with acute lymphoblastic
leukemia or chronic myelogenous leukemia. Our results suggest that KIR
could impact outcome and donor KIR haplotype with Cen-B confer significant
survival benefits to HLA-identical sibling HSCT.

TEL-AML1 Corrupts Hematopoietic Stem Cells to Persist in the Bone
Marrow and Initiate Leukemia

Jeffrey W. Schindler, D Van Buren, A Foudi, O Krejci, J Qin, SH Orkin, and H Hock
Cell Stem Cell 5, 43–53, July 2, 2009
http://dx.doi.org:/10.1016/j.stem.2009.04.019

The initial steps in the pathogenesis of acute leukemia remain incompletely
understood. The TELAML1 gene fusion, the hallmark translocation in Childhood
Acute Lymphoblastic Leukemia and the first hit, occurs years before the clinical
disease, most often in utero. We have generated mice in which TEL-AML1
expression is driven from the endogenous promoter and can be targeted to
specific populations. TEL-AML1 renders mice prone to malignancy after
chemical mutagenesis when expressed in hematopoietic stem cells (HSCs),
but not in early lymphoid progenitors. We reveal that TEL-AML1 markedly
increases the number of HSCs and predominantly maintains them in the
quiescent (G0) stage of the cell cycle. TEL-AML1+ HSCs retain self renewal
properties and contribute to hematopoiesis, but fail to out-compete normal
HSCs. Our work shows that stem cells are susceptible to subversion by weak
oncogenes that can subtly alter their molecular program to provide a latent
reservoir for the accumulation of further mutations.

Factors Affecting the Outcome of Related Allogeneic Hematopoietic
Cell Transplantation in Patients with Fanconi Anemia

Mouhab Ayas, K Siddiqui, A Al-Jefri, , …, A Al-Musa, A Al-Seraihy
Biol Blood Marrow Transplant 20 (2014) 1599e1603
http://dx.doi.org/10.1016/j.bbmt.2014.06.016

Hematopoietic cell transplantation (HCT) can cure bone marrow failure in
patients with Fanconi Anemia (FA), and it is generally accepted that these
patients should receive low-intensity conditioning because of the underlying
DNA repair defect in their cells. Outcomes for recipients of matched related
HCT have generally been favorable, but only a few studies have scrutinized
the factors that may affect the eventual outcome of these patients. This
retrospective analysis of 94 pediatric patients with FA who underwent related
HCT at King Faisal Specialist Hospital & Research Center was carried out to
attempt to identify factors that may affect outcome. Results showed overall
survival (OS) probabilities of 92.5%, 89%, and 86% at 1, 5, and 10 years,
respectively. In univariate analysis, use of higher dose cyclophosphamide
(CY) (60 mg/kg) conditioning was associated with a better 10-year OS than
lower dose CY (20 mg/kg) conditioning (91% versus 82%, respectively;
P < .035), and use of radiation-containing regimens was associated with a
significantly lower 10-year OS than nonradiation regimens (76% versus 91%,
respectively; P < .005). Of the 4 regimens used in this study, the fludarabine-
based regimen was associated with the highest survival (95.2%; P < .034).
The use of the higher dose CY (60 mg/kg) was associated with a
significantly increased incidence of hemorrhagic cystitis (HC) (20% versus 5.6%
respectively; P < .049). Three patients (3%) developed squamous cell carcinoma
(2 oropharyngeal and 1 genitourinary), at 9.4, 5.4, and 13.3 years after HCT;
2 of them had radiation containing conditioning. In conclusion, our data suggest
that although using a higher dose CY (60 mg/kg)
conditioning regimen may be associated with better survival, it is also associated
with a significantly increased risk of HC. The addition of fludarabine to the low-dose
CY (20 mg/kg) is associated with the best survival. On the other hand, radiation-
containing regimens are associated with significantly lower survival.

Donor Cell Leukemia: A Review

Daniel H. Wiseman
Biol Blood Marrow Transplant 17: 771-789 (2011)
http://dx.doi.org:/10.1016/j.bbmt.2010.10.010

Relapse of acute leukemia following hematopoietic stem cell transplantation
(HSCT) usually represents return of an original disease clone, having evaded
eradication by pretransplant chemo-/radiotherapy, conditioning, or posttransplant
graft-versus-leukemia (GVL) effect. Rarely, acute leukemia can develop
de novo in engrafted cells of donor origin. Donor cell leukemia (DCL) was
first recognized in 1971, but for many years, the paucity of reported cases
suggested it to be a rare phenomenon. However, in recent years, an upsurge
in reported cases (in parallel with advances in molecular chimerism monitoring)
suggest that it may be significantly more common than previously appreciated;
emerging evidence suggests that DCL might represent up to 5% of all post-
transplant leukemia ‘‘relapses.’’ Recognition of DCL is important for several
reasons. Donor-derivation of the leukemic clone has implications when selecting
appropriate therapy, because seeking to enhance an allogeneic GVL effect
would intuitively not have the same role as in standard recipient-derived
relapses. There are also broader implications for donor selection and workup,
particularly given the growing popularity of nonmyeloblative HSCTand
corresponding rising age of the potential donor pool. Identification of DCL
raises potential concerns over future health of the donor, posing ethical
dilemmas regarding responsibilities toward donor notification (particularly
in the context of cord blood transplantation). The entity of DCL is also of
research interest, because it might provide a unique human model for studying
the mechanisms of leukemogenesis in vivo. This review presents and collates
all reported cases of DCL, and discusses the various strategies, controversies,
and pitfalls when investigating origin of posttransplant relapse. Putative etiologic
factors and mechanisms are proposed, and attempts made to address the
difficult ethical questions posed by discovery of donor-derived malignancy
within a HSCT recipient.

Feasible Outcomes of T Cell-Replete Haploidentical Stem Cell
Transplantation with Reduced-Intensity Conditioning in Patients
with Myelodysplastic Syndrome

Seung-Hwan Shin, Jung-Ho Kim, Young-Woo Jeon, …,, Woo-Sung Min,
Yoo-Jin Kim, Je-Hwan Lee
Biol Blood Marrow Transplant 21 (2015) 342e349
http://dx.doi.org/10.1016/j.bbmt.2014.10.031

Even with the recent optimization of haploidentical stem cell transplantation
(SCT), its role for patients with myelodysplastic syndrome (MDS) or acute
myeloid leukemia evolving from MDS (sAML) should be validated. We
analyzed the outcomes of consecutive 60 patients with MDS or sAML
who received T cell-replete haploidentical SCT after reduced-intensity
conditioning with fludarabine, busulfan, and rabbit antithymocyte globuline
800 cGy total body irradiation. Patients achieved a rapid neutrophil
engraftment after a median of 12 days (range, 8 to 23) and an early
immune reconstitution without high incidences of acute graft-versus-host
disease (GVHD) II to IV and chronic GVHD (36.7% and 48.3%, respectively).
After a median follow-up of 4 years, incidence of relapse and nonrelapse mortality
and rate of overall survival and disease-free survival was 34.8%, 23.3%, 46.8%,
and 41.9%, respectively. In multivariate analysis, the disease status at peak was
a significant predictor for relapse (lower-risk MDS versus higher-risk MDS or sAML;
hazard ratio [HR], 5.69; 95% confidence interval [CI], 1.45 to 22.29; P <.013)
and disease-free survival (HR, 4.44; 95% CI, 1.14 to 17.34; P <.032). Chronic
GVHD was an additional significant predictor for relapse (no versus yes; HR,
2.87; 95% CI, 1.03 to 7.51; P <.043). Our T cell-replete haploidentical SCT
may be a feasible option for patients with MDS and sAML without conventional
donors.

Extramedullary Relapse of Acute Leukemia after Allogeneic Hematopoietic
Stem Cell Transplantation: Different Characteristics between Acute
Myelogenous Leukemia and Acute Lymphoblastic Leukemia

Ling Ge, Fan Ye, X Mao, …, C Ruan, Depei Wu, Xiaowen Tang
Biol Blood Marrow Transplant 20 (2014) 1040e1047
http://dx.doi.org/10.1016/j.bbmt.2014.03.030

Extramedullary relapse (EMR) of acute leukemia (AL) after allogeneic
hematopoietic stem cell transplantation (allo-HSCT) is a contributor to post-
transplantation mortality and remains poorly understood, especially the
different characteristics of EMR in patients with acute myelogenous
leukemia (AML) and those with acute lymphoblastic leukemia (ALL).
To investigate the incidence, risk factors, and clinical outcomes of EMR
for AML and ALL, we performed a retrospective analysis of 362 patients
with AL who underwent allo-HSCT at the First affiliated Hospital of Soochow
University between January 2001 and March 2012. Compared with patients
with AML, those with ALL had a higher incidence of EMR (12.9% versus
4.6%; P < .009). The most common site of EMR was the central nervous
system, especially in the ALL group. Multivariate analyses identified the
leading risk factors for EMR in the patients with AML as advanced disease
status at HSCT, hyperleukocytosis at diagnosis, history of extramedullary
leukemia before HSCT, and a total body irradiationebased conditioning
regimen, and the top risk factors for EMR in the patients with ALL as
hyperleukocytosis at diagnosis, adverse cytogenetics, and transfusion
of peripheral blood stem cells. The prognosis for EMR of AL is poor,
and treatment options are very limited; however, the estimated 3-year
overall survival (OS) was significantly lower in patients with AML
compared with those with ALL (0 versus 18.5%; P < .000). The
characteristics of post-allo-HSCT EMR differed between the patients
with AML and those with ALL, possibly suggesting different pathogenetic
mechanisms for EMR of AML and EMR of ALL after allo-HSCT; further
investigation is needed.

French Multicenter 22-Year Experience in Stem Cell Transplantation
for Beta-Thalassemia Major: Lessons and Future Directions

Claire Galambrun, C Pondarré, Yves Bertrand, …,C Badens, I Thuret, for the
French Rare Disease Center for Thalassemia and the French Society of Bone
Marrow Transplantation
Biol Blood Marrow Transplant 19 (2013) 62e68
http://dx.doi.org/10.1016/j.bbmt.2012.08.005

Although hematopoietic stem cell transplantation (HSCT) offers curative
potential for beta-thalassemia major (beta-TM), it is associated with a
variable but significant incidence of graft rejection. We studied the French
national experience for improvement over time and the potential benefit
of antithymocyte globulin (ATG). Between December 1985 and December
2007, 108 patients with beta-TM underwent HSCT in 21 different French
transplantation centers. The majority of patients received a matched sibling
transplant (n = 96) and a busulfan- and cyclophosphamide-based conditioning
regimen (n = 95), also with ATG in 57 cases. Ninety five of the 108 patients
survived, with a median follow-up of 12 years. Probabilities of 15-year survival
and thalassemia-free survival after first HSCT were 86.8% and 69.4%, respectively.
Graft failure occurred in 24 patients, 11 of whom underwent a second HSCT.
The use of ATG was associated with a decrease in rejection rate from 35% to 10%.
Thalassemia-free survival improved significantly with time, reaching 83% in the
54 patients undergoing HSCT after 1994 (median time of HSCT). In view of the
increased risk of graft rejection after matched sibling HSCT, current French
national guidelines recommend, for all children at risk for beta-TM, the systematic
addition of ATG to the myeloablative conditioning regimen and special attention
to optimize transfusion and chelation therapy in the pretransplantation period.

Extramedullary Relapse of Acute Myelogenous Leukemia after
Allogeneic Hematopoietic Stem Cell Transplantation: Better
Prognosis Than Systemic Relapse

Melhem Solh, Todd E. DeFor, Daniel J. Weisdorf, Dan S. Kaufman
Biol Blood Marrow Transplant 18: 106-112 (2012)
http://dx.doi.org:/10.1016/j.bbmt.2011.05.023

Allogeneic hematopoietic cell transplantation (HSCT) is considered a curative
treatment for acute myelogenous leukemia (AML). Extramedullary relapse after
HSCT for AML is a rare event and is less well defined than systemic, hematologic
relapse. We retrospectively studied all patients with AML (n = 436) who underwent
HSCT at the University of Minnesota between 1996 and 2008 who developed
either a bone marrow (BM) or extramedullary (EM) relapse, and examined the
incidence and risk factors for BM and EM relapse. Of 128 patients who relapsed
post-HSCT, 25 had relapse in EM sites, either isolated (n = 13) or with concurrent
BM relapse (n = 12). Relapse sites included bone (n = 1), central nervous system
(n=5 6), gastrointestinal (n=5 4), lymphatic (n = 4), skin (n = 5), genitourinary
(n=5 1), pulmonary (n = 1), and soft tissue (n = 3). The time to relapse was longer
in the EM sites (median, 328 days vs 168 days). Patients with EM relapse were
more likely to have had preceding acute graft-versus-host disease (GVHD) (77%
vs 49%; P = .03) or chronic GVHD (46% vs 15%; P < .02) compared with those
with BM relapse. The 6-month survival post-relapse was significantly better in
patients with isolated EM relapse (69%) compared with those with combined
EM and BM relapse (8%) or those with BM relapse alone (27%) (P <.01).
Compared with local therapy alone, systemic therapy yielded better 6-month
survival in patients with EM relapse. This study suggests differing pathogenesis
of BM relapse versus EM relapse of AML after allogeneic HSCT. GVHD and its
accompanying graft-versus-leukemia effect may better protect BM sites, but
patients with EM relapse have better responses to combined therapy and
improved survival compared with those with BM relapse.

Hematopoietic Cell Transplantation for Thalassemia: A Global
Perspective BMT Tandem Meeting 2013

Parinda A. Mehta, Lawrence B. Faulkner
Biol Blood Marrow Transplant 19 (2013) S70eS73
http://dx.doi.org/10.1016/j.bbmt.2012.10.025

Hematopoietic cell transplantation (HCT) remains the sole available curative
option for patients with β-thalassemia major. Expanded and improved supportive
therapies for thalassemia now routinely extend the life span of affected individuals
well into adulthood. Consequently, in regions of the world where this care is
readily available, HCT has been pursued infrequently, in part owing to concerns
about an expected lack of balance between risks and benefits. More recently,
however, recognition of significant health problems in older patients with
thalassemia, along with recognition of increased risks of graft-versus-host
disease (GVHD), graft rejection, and impaired organ function leading to inferior
HCT outcomes in this particular group, seem to be turning the wheels and tipping
the balance again in the direction of consideration for earlier HCTs. In contrast,
in countries where thalassemia is most prevalent (>100,000 new children born
each year in Middle East and southeast Asia), lack of supportive care standards
together with often insufficient access to dedicated health care facilities, results
in the majority of these children not reaching adulthood, further supporting the
need for expanded access to HCT for these patients. The cost of HCT is equivalent
to that of a few years of noncurative supportive care, such that HCT in low-risk
young children with a compatible sibling is justified not only medically and ethically
but also financially. International cooperation can play a major role in increasing
access to safe and affordable HCT in countries where there is a considerable
shortage of transplantation centers. In this article, we review the current status
of bone marrow transplantation for thalassemia major, with particular emphasis
on a global prospective.

Hematopoietic Stem Cell Transplantation in Autoimmune Diseases: The
Ahmedabad Experience

AV Vanikar, PR Modi, RD Patel, KV Kanodia, VR Shah, VB Trivedi, HL Trivedi
Transplantation Proceedings, 39, 703–708 (2007)
http://dx.doi.org:/10.1016/j.transproceed.2007.01.070

Introduction. Autoimmune disease represents a (AD) breakdown of natural
tolerance against autoreactive antigens leading to a high mortality and morbidity.
The reaction is usually polyclonal; T- and B-cell components of the hematopoietic
system are responsible for disease progression. Allogeneic/ autologous
hematopoietic stem cell transplantation (HSCT) are the current modalities
for treating drug-resistant AD. Patients and Methods. We present a single-
center retrospective evaluation of allogeneic HSCT with nonmyelo-ablative,
low-intensity conditioning in nine patients (five males, four females) with
pemphigus vulgaris (PV) and 27 patients with systemic lupus erythematosus
(SLE; 3 males, 24 females). The mean follow-up period was 4.24 years for PV
and 4.9 years for SLE. Cytokine-mobilized HSC from unmatched related donors,
with mean dose of 21.3108 nucleated cells/kg body weight (BW; mean CD34⁺
count, 6 x 10⁶/kg BW) was administered in to the thymus as well as the portal and
peripheral circulations of recipients. Cyclosporine (4 + 1 mg/kg BW per day) and
prednisolone (10 mg/kg BW per day) were administered for 6 months to protect
mixed chimerism. A subset of patients with cross-gender donors were analyzed
for peripheral blood chimerism at 1 month post-HSCT and every 3 months
thereafter. Results. Sustained clinical remission with peripheral lymphohemato-
poietic chimerism of 0.7 + 0.3% was observed in PV, whereas SLE relapsed after
mean of 7.35 months of disease-free interval associated with fall in chimerism
from 5 + 3% to 0.08 + 0.03%. Conclusion. HSCT was effective to achieve early
clinical remission of PV; and in SLE relapsed after a 7.35-month disease-free
interval accompanied by a fall in mixed lymphohematopoietic chimerism.

Hematopoietic Stem Cell Transplantation in Children and Young Adults
with Secondary Myelodysplastic Syndrome and Acute Myelogenous
Leukemia after Aplastic Anemia

Ayami Yoshimi, B Strahm, I Baumann, I Furlan, S Schwarz, …, CM Niemeyer
Biol Blood Marrow Transplant 20 (2014) 421-434
http://dx.doi.org/10.1016/j.bbmt.2013.11.031

Secondary myelodysplastic syndrome and acute myelogenous leukemia
(sMDS/sAML) are the most serious secondary events occurring after immuno-
suppressive therapy in patients with aplastic anemia. Here we evaluate the
outcome of hematopoietic stem cell transplantation (HSCT) in 17 children
and young adults with sMDS/sAML after childhood aplastic anemia. The
median interval between the diagnosis of aplastic anemia and the development
of sMDS/sAML was 2.9 years (range, 1.2 to 13.0 years). At a median age of
13.1 years (range, 4.4 to 26.7 years), patients underwent HSCT with bone
marrow (n = 6) or peripheral blood stem cell (n = 11) grafts from HLA-
matched sibling donors (n = 2), mismatched family donors (n = 2), or
unrelated donors (n = 13). Monosomy 7 was detected in 13 patients. The
preparative regimen consisted of busulfan, cyclophosphamide, and melphalan
in 11 patients and other agents in 6 patients. All patients achieved neutrophil
engraftment. The cumulative incidence of grade II-IV acute graft-versus-host
disease (GVHD) was 47%, and that of chronic GVHD was 70%. Relapse
occurred in 1 patient. The major cause of death was transplant-related
complication (n = 9).Overall survival and event-free survival at 5 years after
HSCT were both 41%.In summary, this study indicates that HSCT is a curative
therapy for some patients with sMDS/sAML after aplastic anemia. Future
efforts should focus on reducing transplantation-related mortality.

Hematopoietic stem cells: An overview

Youssef Mohamed Mosaad
Transfusion and Apheresis Science 51 (2014) 68–82
http://dx.doi.org/10.1016/j.transci.2014.10.016

Considerable efforts have been made in recent years in understanding the
mechanisms that govern hematopoietic stem cell (HSC) origin, development,
differentiation, self-renewal, aging, trafficking, plasticity and trans-differentiation.
Hematopoiesis occurs in sequential waves in distinct anatomical locations during
development and these shifts in location are accompanied by changes in the
functional status of the stem cells and reflect the changing needs of the
developing organism. HSCs make a choice of either self-renewal or committing
to differentiation. The balance between self-renewal and differentiation is
considered to be critical to the maintenance of stem cell numbers. It is still
under debate if HSC can rejuvenate infinitely or if they do not possess ‘‘true”
self-renewal and undergo replicative senescence such as any other somatic
cell. Gene therapy applications that target HSCs offer a great potential for the
treatment of hematologic and immunologic diseases. However, the clinical
success has been limited by many factors. This review is intended to
summarize the recent advances made in the human HSC field, and will
review the hematopoietic stem cell from definition through development
to clinical applications.

HLA epitope based matching for transplantation

René J. Duquesnoy
Transplant Immunology 31 (2014) 1–6
http://dx.doi.org/10.1016/j.trim.2014.04.004

As important risk factors for transplant rejection and failure, HLA antibodies
are now recognized as being specific for epitopes which can be defined
structurally with amino acid differences between HLA alleles. Donor–recipient
compatibility should therefore be assessed at the epitope rather than the
antigen level. HLA Matchmaker is a computer algorithm that considers each
HLA antigen as a series of small configurations of polymorphic residues
referred to as eplets as essential components of HLA epitopes. It includes
epitopes on antigens encoded by all HLA-A, B, C, DR, DQ and DP loci as
well as MICA. HLA epitopes have two characteristics namely antigenicity, i.e.
the reactivity with antibody and immunogenicity, i.e. the ability of eliciting
an antibody response. This article addresses the relevance of determining
epitope-specificities of HLA antibodies, the effect of epitope structure on
technique-dependent antibody reactivity and the identification of acceptable
mismatches for sensitized patients considered for transplantation. Permissible
mismatching for non-sensitized patients aimed to prevent or reduce HLA
antibody responses could consider epitope loads of mismatched antigens and
the recently developed nonself-self paradigm of epitope immunogenicity.

Impact of HLA Mismatch Direction on the Outcome of Unrelated Bone
Marrow Transplantation: A Retrospective Analysis from the Japan
Society for Hematopoietic Cell Transplantation

Junya Kanda, T Ichinohe, S Fuji, Y Maeda, K Ohashi, …, Y Atsuta,
Y Kanda, on behalf of the HLA Working Group of the Japan Society
for Hematopoietic Cell Transplantation
Biol Blood Marrow Transplant 21 (2015) 305e311
http://dx.doi.org/10.1016/j.bbmt.2014.10.015

The relative desirability of an unrelated donor with a bidirectional 1-locus
mismatch (1MM-Bi), a 1-locus mismatch only in the graft-versus-host direction
(1MM-GVH), or a 1-locus mismatch only in the host versus-graft direction
(1MM-HVG) is not yet clear. We analyzed adult patients with leukemia or
myelodysplastic syndrome who received a first allogeneic stem cell transplant
from an HLA-A, -B, -C, and -DRB1 matched or 1-allele mismatched unrelated
donor in Japan. The effects of 1MM-Bi (n = 1020), 1MM-GVH (n = 83), and
1MM-HVG (n = 83) compared with a zero mismatch (0MM) (n = 2570)
were analyzed after adjusting for other significant variables. The risk of
grades III to IV acute graft-versus-host disease (GVHD) was higher with
marginal significance in the 1MM-GVH group than in the 0MM group
(hazard ratio, 1.85; P = .014). However, there was no significant difference
in overall or nonrelapse mortality between the 1MM-GVH and 0MM groups.
There was no significant difference in acute GVHD or overall or nonrelapse
mortality between the 1MM-HVG and 0MM groups. The risks of acute
GVHD and overall mortality were significantly higher in the 1MM-Bi group
than in the 0MM group. These findings indicate that unrelated donors with
1MM-GVH and 1MM-HVG are both good candidates for patients without an
HLA-matched unrelated donor in a Japanese cohort.

ABO incompatibility between donor and recipient and clinical
outcomes in allogeneic stem cell transplantation

James Goldman, Jane Liesveld, Diane Nichols, Joanna Heal, Neil Blumberg
Leukemia Research 27 (2003) 489–491 PII: S0145-2126(02)00259-X

We performed a retrospective, cohort study to evaluate the impact on recipient
survival of ABO incompatibility between recipient and donor after allogeneic
stem cell transplantation, primarily involving marrow-derived cells. No
statistically significant difference was noted in survival for 153 patients
with acute or chronic leukemia or myelodysplastic syndrome receiving
ABO identical or ABO mismatched allografts. Five patients who had
allografts that were bidirectionally incompatible (both donor cells and
plasma incompatible) did have significantly poorer survival than the other
recipients, similar to the experience reported in one other cohort study.
However, these patients had other risks for mortality, including being
older and receiving transplants from matched, unrelated donors. Our
data do not support a significant role for ABO donor–recipient matching in
allogeneic stem cell transplantation.

Allogeneic Hematopoietic Cell Transplantation Outcomes in
Acute Myeloid Leukemia: Similar Outcomes Regardless of
Donor Type

Erica D. Warlick, RP de Latour, R Shanley, …, Gerard Socie
Biol Blood Marrow Transplant 21 (2015) 357e363
http://dx.doi.org/10.1016/j.bbmt.2014.10.030

The use of alternative donor transplants is increasing as the transplantation-
eligible population ages and sibling donors are less available. We
evaluated the impact of donor source on transplantation outcomes for
adults with acute myeloid leukemia undergoing myeloablative (MA) or
reduced-intensity conditioning (RIC) transplantation. Between January 2000
and December 2010, 414 consecutive adult patients with acute myeloid
leukemia in remission received MA or RIC allogeneic transplantation from
either a matched related donor (n = 187), unrelated donor (n = 76), or
umbilical cord blood donor (n = 151) at the University of Minnesota or
Hôpital St. Louis in Paris. We noted similar 6-year overall survival
across donor types: matched related donor, 47% (95% confidence interval
[CI], 39% to 54%); umbilical cord blood, 36% (95% CI, 28% to 44%);
matched unrelated donor, 54% (95% CI, 40% to 66%); and mismatched
unrelated donor, 51% (95% CI, 28% to 70%) (P < .11). Survival differed
based on conditioning intensity and age, with 6-year survival of 57% (95% CI,
47% to 65%), 39% (95% CI, 28% to 49%), 23% (95% CI, 6% to 47%), 47%
(95% CI, 36% to 57%), and 28% (95% CI, 17% to 41%) for MA age 18 to 39,
MA age 40þ, or RIC ages 18 to 39, 40 to 56, and 57 to 74, respectively
(P < .01). Relapse was increased with RIC and lowest in younger patients
receiving MA conditioning (hazard ratio, 1.0 versus 2.5 or above for all RIC
age cohorts), P <.01. Transplantation-related mortality was similar across
donor types. In summary, our data support the use of alternative donors as
a graft source with MA or RIC for patients with acute myeloid leukemia
when a sibling donor is unavailable.

A Novel Reduced-Intensity Conditioning Regimen for Unrelated Umbilical
Cord Blood Transplantation in Children with Nonmalignant Diseases

Suhag H. Parikh, A Mendizabal, CL Benjamin, KV Komandur, J Antony, et al.
Biol Blood Marrow Transplant 20 (2014) 326e336
http://dx.doi.org/10.1016/j.bbmt.2013.11.021

Reduced-intensity conditioning (RIC) regimens have the potential to decrease
transplantation-related morbidity and mortality. However, engraftment
failure has been prohibitively high after RIC unrelated umbilical cord blood
transplantation (UCBT) in chemotherapy-naïve children with nonmalignant
diseases (NMD). Twenty-two children with a median age of 2.8 years, many
with severe comorbidities and prior viral infections, were enrolled in a novel RIC
protocol consisting of hydroxyurea, alemtuzumab, fludarabine, melphalan, and
thiotepa followed by single UCBT. Patients underwent transplantation for
inherited metabolic disorders (n = 8), primary immunodeficiencies (n = 9),
hemoglobinopathies (n = 4) and Diamond Blackfan anemia (n = 1). Most
umbilical cord blood (UCB) units were HLA-mismatched with median infused
total nucleated cell dose of 7.9 107/kg. No serious organ toxicities were
attributable to the regimen. The cumulative incidence of neutrophil engraftment
was 86.4% (95% confidence interval [CI], 65% to 100%) in a median of 20
days, with the majority sustaining > 95% donor chimerism at 1 year. Cumulative
incidence of acute graft-versus-host disease (GVHD) grades II to IV and III to IV
by day 180 was 27.3% (95% CI, 8.7% to 45.9%) and 13.6% (95 CI, 0% to 27.6%),
respectively. Cumulative incidence of extensive chronic GVHD was 9.1% (95%
CI, 0% to 20.8%). The primary causes of death were viral infections (n ¼ 3), acute
GVHD (n = 1) and transfusion reaction (n ¼ 1). One-year overall and event-free
survivals were 77.3% (95% CI, 53.7% to 89.8%) and 68.2% (95% CI, 44.6%
to 83.4%) with 31 months median follow-up. This is the first RIC protocol
demonstrating durable UCB engraftment in children with NMD. Future risk-
based modifications of this regimen could decrease the incidence of viral
infections. (www.clinicaltrials.gov/NCT00744692).

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Biomarker Guided Therapy

Posted in Cancer and Current Therapeutics, CANCER BIOLOGY & Innovations in Cancer Therapy, Cancer Screening, Cardiomyopathy, Cardiovascular Pharmacogenomics, Cardiovascular Research, Clinical Diagnostics, Computational Biology/Systems and Bioinformatics, Curation, Diabetes Mellitus, Diagnostics and Lab Tests, Electrophysiology, Frontiers in Cardiology and Cardiovascular Disorders, Genomic Testing: Methodology for Diagnosis, Genomics Pharmacy, Hematology, HTN, Myocardial Ischemia, Nephrology, Pharmacotherapy of Cardiovascular Disease, tagged Cancer - General, Cardiomyopathy, chronic renal failure, functional proteomics, genomics, Hypertension, pharmacogenomics, prognosis markers, Proteomics, therapeutic monitoring, type 2DM on February 1, 2015| Leave a Comment »

Biomarker Guided Therapy

Writer and Curator: Larry H. Bernstein, MD, FCAP

Novel serum protein biomarker panel revealed by mass spectrometry and its prognostic value in breast cancer

Liping Chung, K Moore, L Phillips, FM Boyle, DJ Marsh and RC Baxter
Breast Cancer Research 2014, 16:R63
http://breast-cancer-research.com/content/16/3/R63

Introduction: Serum profiling using proteomic techniques has great potential to detect biomarkers that might improve diagnosis and predict outcome for breast cancer patients (BC). This study used surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS) to identify differentially expressed proteins in sera from BC and healthy volunteers (HV), with the
goal of developing a new prognostic biomarker panel.
Methods: Training set serum samples from 99 BC and 51 HV subjects were applied to four adsorptive chip surfaces (anion-exchange, cation-exchange, hydrophobic, and metal affinity) and analyzed by time-of-flight MS. For validation, 100 independent BC serum samples and 70 HV samples were analyzed similarly. Cluster analysis of protein spectra was performed to identify protein patterns related to BC and HV groups. Univariate and multivariate statistical analyses were used to develop a protein panel to distinguish breast cancer sera from healthy sera, and its prognostic potential was evaluated.
Results: From 51 protein peaks that were significantly up- or downregulated in BC patients by univariate analysis, binary logistic regression yielded five protein peaks that together classified BC and HV with a receiver operating characteristic (ROC) area-under-the-curve value of 0.961. Validation on an independent patient cohort confirmed the five-protein parameter (ROC value 0.939). The five-protein parameter showed positive association with large tumor size (P = 0.018) and lymph node involvement (P = 0.016). By matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, immunoprecipitation and western blotting the proteins were identified as a fragment of apolipoprotein H (ApoH), ApoCI, complement C3a, transthyretin, and ApoAI. Kaplan-Meier analysis on 181 subjects after median follow-up of >5 years demonstrated that the panel significantly predicted disease-free survival (P = 0.005), its efficacy apparently greater in women with estrogen receptor (ER)-negative tumors (n = 50, P = 0.003) compared to ER-positive (n = 131, P = 0.161), although the influence of ER status needs to be confirmed after longer follow-up.
Conclusions: Protein mass profiling by MS has revealed five serum proteins which, in combination, can distinguish between serum from women with breast cancer and healthy control subjects with high sensitivity and specificity. The five-protein panel significantly predicts recurrence-free survival in women with ER-negative tumors and may have value in the management of these patients.

Variants of uncertain significance in BRCA: a harbinger of ethical and policy issues to come?

Jae Yeon Cheon, Jessica Mozersky and Robert Cook-Deegan
Genome Medicine 2014, 6:121
http://genomemedicine.com/content/6/12/121

After two decades of genetic testing and research, the BRCA1 and BRCA2 genes are two of the most well-characterized genes in the human genome. As a result, variants of uncertain significance (VUS; also called variants of unknown significance) are reported less frequently than for genes that have been less thoroughly studied. However, VUS continue to be uncovered, even for BRCA1/2. The increasing use of multi-gene panels and whole-genome and whole-exome sequencing will lead to higher rates of VUS detection because more genes are being tested, and most genomic loci have been far less intensively characterized than BRCA1/2. In this article, we draw attention to ethical and policy-related issues that will emerge. Experience garnered from BRCA1/2 testing is a useful introduction to the challenges of detecting VUS in other genetic testing contexts, while features unique to BRCA1/2 suggest key differences between the BRCA experience and the current challenges of multi-gene panels in clinical care. We propose lines of research and policy development, emphasizing the importance of pooling data into a centralized open-access database for the storage of gene variants to improve VUS interpretation. In addition, establishing ethical norms and regulated practices for sharing and curating data, analytical algorithms, interpretive frameworks and patient re-contact are important policy areas.

The Significance of Normal Pretreatment Levels of CA125 (<35 U/mL) in Epithelial Ovarian Carcinoma

Joseph Menczer, Erez Ben-Shem, Abraham Golan, and Tally Levy
Rambam Maimonides Med J 2015;6 (1):e0005. http://dx.doi.org:/10.5041/RMMJ.10180

Objective: To assess the association between normal CA125 levels at diagnosis of epithelial ovarian carcinoma (EOC) with prognostic factors and with outcome.
Methods: The study group consisted of histologically confirmed EOC patients with normal pretreatment CA125 levels, and the controls consisted of EOC patients with elevated (≥35 U/mL) pretreatment CA125 levels, diagnosed and treated between 1995 and 2112. Study and control group patients fulfilled the following criteria: 1) their pretreatment CA125 levels were assessed; 2) they had full standard primary treatment, i.e. cytoreductive surgery and cisplatin-based chemotherapy; and 3) they were followed every 2–4 months during the first two years and every 4–6 months thereafter.
Results: Of 114 EOC patients who fulfilled the inclusion criteria, 22 (19.3%) had normal pretreatment CA125 levels. The control group consisted of the remaining 92 patients with ≥35 U/mL serum CA125 levels pretreatment. The proportion of patients with early-stage and low-grade disease, with optimal cytoreduction, and with platin-sensitive tumors was significantly higher in the study group than in the control group. The progression-free survival (PFS) and overall survival (OS) were significantly higher in the study group than in the control group on univariate analysis but not on multivariate analysis.

Higher gene expression variability in the more aggressive subtype of chronic lymphocytic leukemia

Simone Ecker, Vera Pancaldi, Daniel Rico and Alfonso Valencia
Genome Medicine (2015) 7:8 http://dx.doi.org:/10.1186/s13073-014-0125-z

Background: Chronic lymphocytic leukemia (CLL) presents two subtypes which have drastically different clinical outcomes, IgVH mutated (M-CLL) and IgVH unmutated (U-CLL). So far, these two subtypes are not associated to clear differences in gene expression profiles. Interestingly, recent results have highlighted important roles for heterogeneity, both at the genetic and at the epigenetic level in CLL progression.
Methods: We analyzed gene expression data of two large cohorts of CLL patients and quantified expression variability across individuals to investigate differences between the two subtypes using different measures and statistical tests. Functional significance was explored by pathway enrichment and network analyses. Furthermore, we implemented a random forest approach based on expression variability to classify patients into disease subtypes.
Results: We found that U-CLL, the more aggressive type of the disease, shows significantly increased variability of gene expression across patients and that, overall, genes that show higher variability in the aggressive subtype are related to cell cycle, development and inter-cellular communication. These functions indicate a potential relation between gene expression variability and the faster progression of this CLL subtype. Finally, a classifier based on gene expression variability was able to correctly predict the disease subtype of CLL patients.
Conclusions: There are strong relations between gene expression variability and disease subtype linking significantly increased expression variability to phenotypes such as aggressiveness and resistance to therapy in CLL.

The Emerging Roles of Thyroglobulin

Yuqian Luo, Yuko Ishido, Naoki Hiroi, Norihisa Ishii, and Koichi Suzuki
Advances in Endocrinology 2014, Article ID 189194, 7 pages http://dx.doi.org/10.1155/2014/189194

Thyroglobulin (Tg), the most important and abundant protein in thyroid follicles, is well known for its essential role in thyroid hormone synthesis. In addition to its conventional role as the precursor of thyroid hormones, we have uncovered a novel function of Tg as an endogenous regulator of follicular function over the past decade. The newly discovered negative feedback effect of Tg on follicular function observed in the rat and human thyroid provides an alternative explanation for the observation of follicle heterogeneity. Given the essential role of the regulatory effects of Tg, we consider that dysregulation of normal Tg function is associated with multiple human thyroid diseases including autoimmune thyroid disease and thyroid cancer. Additionally, extrathyroid Tg may serve a regulatory function in other organs. Further exploration of Tg action, especially at the molecular level, is needed to obtain a better understanding of both the physiological and pathological roles of Tg.

The GUIDE-IT trial will help doctors find a new standard of care for heart failure.

Heart failure affects more than 25 million people worldwide, including 5.8 million in the United States and 6.9 million in Europe. About one to two percent of adults in developed countries have been diagnosed with heart failure; this increases to more than 10 percent in people over age 70. Moreover, heart failure accounts for more than 17 percent of Medicare spending and about 5 percent of total US healthcare spending. The cost to society in the US is about 30 billion dollars a year—and rising.

For people hospitalized due to heart failure, the outlook isn’t encouraging. Following discharge, one in four patients is likely to be back in the hospital in less than a month. With every acute heart failure event that requires readmission, the chances of dying from the disease increase.

Heart failure occurs when the heart is unable to fill with or pump sufficient blood to meet the needs of the body. Some heart failure symptoms—shortness of breath, fatigue and fluid buildup—which are present in other health problems. Heart failure may develop from coronary artery disease, high blood pressure, cardiomyopathy, heart valve disease, arrhythmias, viral or bacterial infections, and congenital heart defects. As a consequence, these patients often have additional diseases (comorbidities) and managing heart failure can be extremely challenging.

There have been no new drugs for heart failure in more than a decade. The last breakthrough was cardiac resynchronization therapy, a device and not a drug. The goals of therapy are to treat heart failure’s underlying causes, reduce symptoms, improve the patient’s quality of life and keep the disease from getting worse.

More than a pump

The heart isn’t just a muscle pumping blood through the body. It is also an endocrine gland that secretes peptides and hormones. When the heart is failing, its stressed cells release larger amounts of substances known as natriuretic peptides, including N-terminal prohormone brain natriuretic peptide, or NT-proBNP.

Roche’s NT-proBNP test measures the levels of this peptide and helps doctors to determine whether patients are suffering from heart failure and to assess their prognosis. Most recently, NT-proBNP has also been shown to help physicians guide and adjust the patient’s drug therapy. The objective of the pivotal GUIDE-IT trial is to demonstrate the efficacy and safety of NT-proBNP guided heart failure therapy.

Sponsored by the National Institutes of Health (NIH), the GUIDE-IT trial will help doctors answer important questions about NT-proBNP’s impact on medical care. About 1100 patients are enrolled in this robustly powered, randomized controlled trial comparing NT-proBNP guided therapy on top of standard care versus standard care alone in high-risk heart failure patients. Its primary endpoint is time to cardiovascular death or first heart failure hospitalization.

With the NT-proBNP biomarker, doctors can create personalized treatment plans for patients to substantially reduce mortality and morbidity. It can be viewed as a companion diagnostic that works with all the drugs recommended by the major guidelines.

Finding new answers

GUIDE-IT will last five years and involve approximately 45 trial sites in the United States. The first group of patients will be enrolled by the end of 2012.

“We need to take a more strategic approach if we are going to meet the AHA/ASA’s 2020 goal of reducing heart failure hospitalizations by 20 percent,” Dr. O’Connor, Chief of the Division of Cardiovascular Medicine at Duke Heart Center in Durham, North Carolina, said at a media briefing held in October at Roche Diagnostics International in Rotkreuz, Switzerland.
The relative and combined ability of: high-sensitivity cardiac troponin T, and N-terminal pro-B-type natriuretic Peptide – to predict cardiovascular events and death in patients with type 2 diabetes.

Hillis GS; Welsh P; Chalmers J; Perkovic V; Chow CK; Li Q; Jun M; Neal B; et al.
http://reference.medscape.com/medline/abstract/24089534?src=wnl_ref_prac_diab

OBJECTIVE Current methods of risk stratification in patients with type 2 diabetes are suboptimal. The current study assesses the ability of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) to improve the prediction of cardiovascular events and death in patients with type 2 diabetes.
RESEARCH DESIGN AND METHODS A nested case-cohort study was performed in 3,862 patients who participated in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial. RESULTS Seven hundred nine (18%) patients experienced a major cardiovascular event (composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke) and 706 (18%) died during a median of 5 years of follow-up. In Cox regression models, adjusting for all established risk predictors, the hazard ratio for cardiovascular events for NT-proBNP was 1.95 per 1 SD increase (95% CI 1.72, 2.20) and the hazard ratio for hs-cTnT was 1.50 per 1 SD increase (95% CI 1.36, 1.65). The hazard ratios for death were 1.97 (95% CI 1.73, 2.24) and 1.52 (95% CI 1.37, 1.67), respectively. The addition of either marker improved 5-year risk classification for cardiovascular events (net reclassification index in continuous model, 39% for NT-proBNP and 46% for hs-cTnT). Likewise, both markers greatly improved the accuracy with which the 5-year risk of death was predicted. The combination of both markers provided optimal risk discrimination.
CONCLUSIONS NT-proBNP and hs-cTnT appear to greatly improve the accuracy with which the risk of cardiovascular events or death can be estimated in patients with type 2 diabetes.

Genetics and Heart Failure: A Concise Guide for the Clinician

Cécile Skrzynia, Jonathan S. Berg, Monte S. Willis and Brian C. Jensen
Current Cardiology Reviews, 2013; 9.

Abstract: The pathogenesis of heart failure involves a complex interaction between genetic and environmental factors. Genetic factors may influence the susceptibility to the underlying etiology of heart failure, the rapidity of disease progression, or the response to pharmacologic therapy. The genetic contribution to heart failure is relatively minor in most multifactorial cases, but more direct and profound in the case of familial dilated cardiomyopathy. Early studies of genetic risk for heart failure focused on polymorphisms in genes integral to the adrenergic and renin-angiotensin-aldosterone system. Some of these variants were found to increase the risk of developing heart failure, and others appeared to affect the therapeutic response to neurohormonal antagonists. Regardless, each variant individually confers a relatively modest increase in risk and likely requires complex interaction with other variants and the environment for heart failure to develop. Dilated cardiomyopathy frequently leads to heart failure, and a genetic etiology increasingly has been recognized in cases previously considered to be “idiopathic”. Up to 50% of dilated cardiomyopathy cases without other cause likely are due to a heritable genetic mutation. Such mutations typically are found in genes encoding sarcomeric proteins and are inherited in an autosomal dominant fashion. In recent years, rapid advances in sequencing technology have improved our ability to diagnose familial dilated cardiomyopathy and those diagnostic tests are available widely. Optimal care for the expanding population of patients with heritable heart failure involves counselors and physicians with specialized training in genetics, but numerous online genetics resources are available to practicing clinicians.

Cardiac Troponin Testing Is Overused after the Rule-In or Rule-Out of Myocardial Infarction

Olaia Rodriguez Fraga, Y Sandoval, SA Love, ZJ McKinney, MAM Murakami, SW Smith, FS Apple
Clinical Chemistry 2015; 61:2 http://dx.doi.org:/10.1373/clinchem.2014.232694

No good studies have systematically evaluated appropriate clinical utilization of cardiac troponin testing in the clinical setting of the rule-in and rule-out of myocardial infarction (MI). Our collective 100-plus years of clinical and laboratory experience suggested that provider test ordering and use of cardiac troponin has been excessive after a diagnosis of MI or no MI has been determined. There is no evidence that supports continuation of cardiac troponin testing after a diagnosis is made.

Number of cTnI results demonstrating excessive orders by diagnosis

Time and Frequency Domain Analysis of Heart Rate Variability and their orrelations in Diabetes Mellitus
T. Ahamed Seyd, V. I. Thajudin Ahamed, Jeevamma Jacob, Paul Joseph K
Intl J Biolog and Life Sciences 2008; 4(1)

Diabetes mellitus (DM) is frequently characterized by autonomic nervous dysfunction. Analysis of heart rate variability (HRV) has become a popular noninvasive tool for assessing the activities of autonomic nervous system (ANS). In this paper, changes in ANS
activity are quantified by means of frequency and time domain analysis of R-R interval variability. Electrocardiograms (ECG) of 16 patients suffering from DM and of 16 healthy volunteers were recorded. Frequency domain analysis of extracted normal to normal interval (NN interval) data indicates significant difference in very low frequency (VLF) power, low frequency (LF) power and high frequency (HF) power, between the DM patients and control group. Time domain measures, standard deviation of NN interval (SDNN), root mean square of successive NN interval differences (RMSSD), successive NN intervals differing more than 50 ms (NN50 Count), percentage value of NN50 count (pNN50), HRV triangular index and triangular interpolation of NN intervals (TINN) also show significant difference between the DM patients and control group.

Power Spectral Density of the RR interval of a 55 year old healthy volunteer

Power Spectral Density of the RR interval of a 62 year old woman suffering

Power Spectral Density of the RR interval of a 62 year old woman suffering
from diabetes for the last 15 years

HRV analysis has gained much importance in recent years, as a technique employed to explore the activity of ANS, and as an important early marker for identifying different pathological conditions. DM is a disease in which the cardiac autonomic activity is progressively compromised. Our investigation indicates that different time domain and frequency domain measures of HRV would be able to provide valuable information regarding the autonomic dysfunction to DM.

Time domain and frequency domain analysis of the RR interval variability of diabetic and normal subjects shows that there is significant difference in these measures for DM patients with respect to normal subjects. Variation of the HRV parameters indicates changes in ANS activity of DM patients. This can provide valid information regarding autonomic neuropathy in people with diabetes. It may be noted that these methods can detect changes before clinical signs appear. So we can expect that these measures enable early detection and treatment/subsequent management of patients and thus can avoid acute and chronic complications.

Multiparametric diagnostics of cardiomyopathies by microRNA signatures

Christine S. Siegismund & Maria Rohde & Uwe Kühl & Dirk Lassner
Microchim Acta 2014 http://dx.doi.org:/10.1007/s00604-014-1249-y

The diagnosis of cardiomyopathies by endomyocardial biopsy analysis is the gold standard for confirmation of causative reasons but is failing if a sample does not contain the area of interest due to focal pathology. Biopsies are revealing an extract of the current situation of the heart muscle only, and the need for global organ-specific or systemic markers is obvious in order to minimize sampling errors. Global markers like specific gene expression signatures in myocardial tissue may therefore reflect the focal situation or condition of the whole myocardium. Besides gene expression profiles, microRNAs (miRNAs) represent a new group of stable biomarkers that are detectable both in tissue and body fluids. Such miRNAs may serve as cardiological biomarkers to characterize inflammatory processes, to confirm viral infections, and to differentiate various forms of infection.
The predictive power of single miRNAs for diagnosis of complex diseases may be further increased if several distinctly deregulated candidates are combined to form a specific miRNA signature. Diagnostic systems that generate disease related miRNA profiles are based on microarrays, bead-based oligo sorbent assays, or on assays based on real-time polymerase chain reactions and placed on microfluidic cards or nanowell plates. Multiparametric diagnostic systems that can measure differentially expressed miRNAs may become the diagnostic tool of the future due to their predictive value with respect to clinical course, therapeutic decisions, and therapy monitoring. We discuss here specific merits, limitations and the potential of currently available analytical platforms for diagnostics of heart muscle diseases based on miRNA profiling.

Predictive value of plasma galectin-3 levels in heart failure with reduced and preserved ejection fraction

Rudolf A. de Boer, DJA Lok, T Jaarsma, P van der Meer, AA Voors, et al.
Annals Med, 2011; 43: 60–68 http://dx.doi.org:/10.3109/07853890.2010.538080

We studied the prognostic value of base-line galectin-3 in a large HF cohort, with preserved and reduced left ventricular ejection fraction (LVEF), and compared this to other biomarkers.
Methods. We studied 592 HF patients who had been hospitalized for HF and were followed for 18 months. The primary end-point was a composite of all-cause mortality and HF hospitalization.
Results. A doubling of galectin-3 levels was associated with a hazard ratio (HR) of 1.97 (1.62–2.42) for the primary outcome (P= 0.001). After correction for age, gender, BNP, eGFR, and diabetes the HR was 1.38 (1.07–1.78; P= 0.015). Galectin-3 levels were correlated with higher IL -6 and CRP levels (P= 0.002). Changes of galectin-3 levels after 6 months did not add prognostic information to the base-line value (n= 291); however, combining plasma galectin-3 and BNP levels increased prognostic value over either biomarker alone (ROC analysis, P = 0.05). The predictive value of galectin-3 was stronger in patients with preserved LVEF (n= 114) compared to patients with reduced LVEF (P= 0.001).
Conclusions. Galectin-3 is an independent marker for outcome in HF and appears to be particularly useful in HF patients with preserved LVEF.

Criteria for the use of omics-based predictors in clinical trials

Lisa M. McShane, MM Cavenagh, TG Lively, DA Eberhard, et al.
Nature 17 Oct 2013; 502: 317-320. http://dx.doi.org:/10.1038/nature12564

The US National Cancer Institute (NCI), in collaboration with scientists representing multiple areas of expertise relevant to ‘omics’-based test development, has developed a checklist of criteria that can be used to determine the readiness of omics-based tests for guiding patient care in clinical trials. The checklist criteria cover issues relating to specimens, assays, mathematical modelling, clinical trial design, and ethical, legal and regulatory aspects. Funding bodies and journals are encouraged to consider the checklist, which they may find useful for assessing study quality and evidence strength. The checklist will be used to evaluate proposals for NCI-sponsored clinical
trials in which omics tests will be used to guide therapy.

M-Atrial Natriuretic Peptide and Nitroglycerin in a Canine Model of Experimental Acute Hypertensive Heart Failure: Differential Actions of 2 cGMP Activating Therapeutics.

Paul M McKie, Alessandro Cataliotti, Tomoko Ichiki, S Jeson Sangaralingham, Horng H Chen, John C Burnett
J Am Heart Assoc 01/2014; 3(1):e000206. http://dx.doi.org:/10.1161/JAHA.113.000206

Systemic hypertension is a common characteristic in acute heart failure (HF). This increasingly recognized phenotype is commonly associated with renal dysfunction and there is an unmet need for renal enhancing therapies. In a canine model of HF and acute vasoconstrictive hypertension we characterized and compared the cardiorenal actions of M-atrial natriuretic peptide (M-ANP), a novel particulate guanylyl cyclase (pGC) activator, and nitroglycerin, a soluble guanylyl cyclase (sGC) activator.
HF was induced by rapid RV pacing (180 beats per minute) for 10 days. On day 11, hypertension was induced by continuous angiotensin II infusion. We characterized the cardiorenal and humoral actions prior to, during, and following intravenous M-ANP (n=7), nitroglycerin (n=7), and vehicle (n=7) infusion. Mean arterial pressure (MAP) was reduced by M-ANP (139±4 to 118±3 mm Hg, P<0.05) and nitroglycerin (137±3 to 116±4 mm Hg, P<0.05); similar findings were recorded for pulmonary wedge pressure (PCWP) with M-ANP (12±2 to 6±2 mm Hg, P<0.05) and nitroglycerin (12±1 to 6±1 mm Hg, P<0.05). M-ANP enhanced renal function with significant increases (P<0.05) in glomerular filtration rate (38±4 to 53±5 mL/min), renal blood flow (132±18 to 236±23 mL/min), and natriuresis (11±4 to 689±37 mEq/min) and also inhibited aldosterone activation (32±3 to 23±2 ng/dL, P<0.05), whereas nitroglycerin had no significant (P>0.05) effects on these renal parameters or aldosterone activation.
Our results advance the differential cardiorenal actions of pGC (M-ANP) and sGC (nitroglycerin) mediated cGMP activation. These distinct renal and aldosterone modulating actions make M-ANP an attractive therapeutic for HF with concomitant hypertension, where renal protection is a key therapeutic goal.

Genome-Wide Association Study of a Heart Failure Related Metabolomic Profile Among African Americans in the Atherosclerosis Risk in Communities (ARIC) Study

Bing Yu, Y Zheng, D Alexander, TA Manolio, A Alonso, JA Nettleton, & E Boerwinkle
Genet Epidemiol 2013; 00:1–6, http://dx.doi.org:/10.1002/gepi.21752

Both the prevalence and incidence of heart failure (HF) are increasing, especially among African Americans, but no large-scale, genome-wide association study (GWAS) of HF-related metabolites has been reported. We sought to identify novel genetic variants that are associated with metabolites previously reported to relate to HF incidence. GWASs of three metabolites identified previously as risk factors for incident HF (pyroglutamine, dihydroxy docosatrienoic acid, and X-11787, being either hydroxy-leucine or hydroxy-isoleucine) were performed in 1,260 African Americans free of HF at the baseline examination of the Atherosclerosis Risk in Communities (ARIC) study. A significant association on chromosome 5q33 (rs10463316, MAF = 0.358, P-value = 1.92 × 10−10) was identified for pyroglutamine. One region on chromosome 2p13 contained a nonsynonymous substitution in N-acetyltransferase 8 (NAT8) was associated with X-11787 (rs13538, MAF = 0.481, P-value = 1.71 × 10−23). The smallest P-value for dihydroxy docosatrienoic acid was rs4006531 on chromosome 8q24 (MAF = 0.400, P-value = 6.98 × 10−7). None of the above SNPs were individually associated with incident HF, but a genetic risk score (GRS) created by summing the most significant risk alleles from each metabolite detected 11% greater risk of HF per allele. In summary, we identified three loci associated with previously reported HF-related metabolites. Further use of metabolomics technology will facilitate replication of these findings in independent samples.

Global Left Atrial Strain Correlates with CHADS2 Risk Score in Patients with Atrial Fibrillation

SK Saha, PL Anderson, G Caracciolo, A Kiotsekoglou, S Wilansky, S Govind, et al.
J Am Soc Echocardiogr 2011; 24(5): 506-512.
http://dx.doi.org:/10.1016/j.echo.2011.02.012

Background: The aim of this cross-sectional study was to explore the association between echocardiographic parameters and CHADS2 score in patients with nonvalvular atrial fibrillation (AF).
Methods: Seventy-seven subjects (36 patients with AF, 41 control subjects) underwent standard twodimensional, Doppler, and speckle-tracking echocardiography to compute regional and global left atrial (LA) strain.
Results: Global longitudinal LA strain was reduced in patients with AF compared with controls (P < .001) and was a predictor of high risk for thromboembolism (CHADS2 score $ 2; odds ratio, 0.86; P = .02). LA strain indexes showed good interobserver and intraobserver variability. In sequential Cox models, the prediction of hospitalization and/or death was improved by addition of global LA strain and indexed LA volume to CHADS2 score (P = .003).
Conclusions: LA strain is a reproducible marker of dynamic LA function and a predictor of stroke risk and cardiovascular outcomes in patients with AF.

Gene Expression and Genetic Variation in Human Atria

Honghuang Lin, EV Dolmatova, MP Morley, KL Lunetta, et al.
Heart Rhythm, HRTHM5533. PII: S1547-5271(13)01226-5
http://dx.doi.org/10.1016/j.hrthm.2013.10.051

Background— The human left and right atria have different susceptibilities to develop atrial fibrillation (AF). However, the molecular events related to structural and functional changes that enhance AF susceptibility are still poorly understood.
Objective— To characterize gene expression and genetic variation in human atria.
Methods— We studied the gene expression profiles and genetic variations in 53 left atrial and 52 right atrial tissue samples collected from the Myocardial Applied Genomics Network (MAGNet) repository. The tissues were collected from heart failure patients undergoing transplantation and from unused organ donor hearts with normal ventricular function. Gene expression was profiled using the Affymetrix GeneChip Human Genome U133A Array. Genetic variation was profiled using the Affymetrix Genome-Wide Human SNP Array 6.0.
Results— We found that 109 genes were differentially expressed between left and right atrial tissues. A total of 187 and 259 significant cis-associations between transcript levels and genetic variants were identified in left and right atrial tissues, respectively. We also found that a SNP at a known AF locus, rs3740293, was associated with the expression of MYOZ1 in both left and right atrial tissues. Conclusion— We found a distinct transcriptional profile between the right and left atrium, and extensive cis-associations between atrial transcripts and common genetic variants. Our results implicate MYOZ1 as the causative gene at the chromosome 10q22 locus for AF.

Atrial Natriuretic Peptide Single Nucleotide Polymorphisms in Patients with Nonfamilial Structural Atrial Fibrillation

Pietro Francia, A Ricotta, A Frattari, R Stanzione, A Modestino, et al.
Clinical Medicine Insights: Cardiology 2013:7 153–159
http://dx.doi.org:/10.4137/CMC.S12239

Background: Atrial natriuretic peptide (ANP) has antihypertrophic and antifibrotic properties that are relevant to AF substrates. The −G664C and rs5065 ANP single nucleotide polymorphisms (SNP) have been described in association with clinical phenotypes, including hypertension and left ventricular hypertrophy. A recent study assessed the association of early AF and rs5065 SNPs in low-risk subjects. In a Caucasian population with moderate-to-high cardiovascular risk profile and structural AF, we conducted a case-control study to assess whether the ANP −G664C and rs5065 SNP associate with nonfamilial structural AF.
Methods: 168 patients with nonfamilial structural AF and 168 age- and sex-matched controls were recruited. The rs5065 and −G664C ANP SNPs were genotyped.
Results: The study population had a moderate-to-high cardiovascular risk profile with 86% having hypertension, 23% diabetes, 26% previous myocardial infarction, and 23% left ventricular systolic dysfunction. Patients with AF had greater left atrial diameter (44 ± 7
vs. 39 ± 5 mm; P , 0.001) and higher plasma NTproANP levels (6240 ± 5317 vs. 3649 ± 2946 pmol/mL; P , 0.01). Odds ratios (ORs)
for rs5065 and −G664C gene variants were 1.1 (95% confidence interval [CI], 0.7–1.8; P = 0.71) and 1.2 (95% CI, 0.3–3.2; P = 0.79), respectively, indicating no association with AF. There were no differences in baseline clinical characteristics among carriers and noncarriers of the −664C and rs5065 minor allele variants.
Conclusions: We report lack of association between the rs5065 and −G664C ANP gene SNPs and AF in a Caucasian population of patients with structural AF. Further studies will clarify whether these or other ANP gene variants affect the risk of different subphenotypes of AF driven by distinct pathophysiological mechanisms.

N-terminal proBNP and mortality in hospitalized patients with heart failure and preserved vs. reduced systolic function: data from the prospective Copenhagen Hospital Heart Failure Study (CHHF)

Kirk, M. Bay, J. Parnerc, K. Krogsgaard, T.M. Herzog, S. Boesgaard, et al.
Eur Journal Heart Failure 6 (2004) 335–341
http://dx.doi.org:/10.1016/j.ejheart.2004.01.002

Preserved systolic function among heart failure patients is a common finding, a fact that has only recently been fully appreciated. The aim of the present study was to examine the value of NT-proBNP to predict mortality in relation to established risk factors among consecutively hospitalised heart failure patients and secondly to characterise patients in relation to preserved and reduced systolic function. Material: At the time of admission 2230 consecutively hospitalised patients had their cardiac status evaluated through determinations of NT-proBNP, echocardiography, clinical examination and medical history. Follow-up was performed 1 year later in all patients. Results: 161 patients fulfilled strict diagnostic criteria for heart failure (HF). In this subgroup of patients 1-year mortality was approximately 30% and significantly higher as compared to the remaining non-heart failure population (approx. 16%). Using univariate analysis left ventricular ejection fraction (LVEF), New York Heart Association classification (NYHA) and plasma levels of NT-proBNP all predicted mortality independently. However, regardless of systolic function, age and NYHA class, risk-stratification was provided by measurements of NT-proBNP. Having measured plasma levels of NT-proBNP, LVEF did not provide any additional prognostic information on mortality among heart failure patients (multivariate analysis).
Conclusion: The results show that independent of LVEF, measurements of NT-proBNP add additional prognostic information. It is concluded that NT-proBNP is a strong predictor of 1-year mortality in consecutively hospitalised patients with heart failure with preserved as well as reduced systolic function.

N-terminal pro-B-type natriuretic peptide and the prediction of primary cardiovascular events: results from 15-year follow-up of WOSCOPS

Paul Welsh, Orla Doolin, Peter Willeit, Chris Packard, Peter Macfarlane, et al.
Eur Heart Journal 2014. http://eurheartj.oxfordjournals.org/

Aims: To test whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) was independently associated with, and improved the prediction of, cardiovascular disease (CVD) in a primary prevention cohort.
Methods and results: In the West of Scotland Coronary Prevention Study (WOSCOPS), a cohort of middle-aged men with hypercholesterolemia at a moderate risk of CVD, we related the baseline NT-proBNP (geometric mean 28 pg/mL) in 4801 men to the risk of CVD over 15 years during which 1690 experienced CVD events. Taking into account the competing risk of non-CVD death, NT-proBNP was associated with an increased risk of all CVD [HR: 1.17 (95% CI: 1.11–1.23) per standard deviation increase in log NT-proBNP] after adjustment for classical and clinical cardiovascular risk factors plus C-reactive protein. N-terminal pro-B-type natriuretic peptide was more strongly related to the risk of fatal [HR: 1.34 (95% CI: 1.19–1.52)] than non-fatal CVD [HR: 1.17 (95% CI: 1.10–1.24)] (P ¼ 0.022). The addition of NT-proBNP to traditional risk factors improved the C-index (+0.013; P , 0.001). The continuous net reclassification index improved with the addition of NT-proBNP by 19.8% (95% CI: 13.6–25.9%) compared with 9.8% (95% CI: 4.2–15.6%) with the addition of C-reactive protein. N-terminal pro-B-type natriuretic peptide correctly reclassified 14.7% of events, whereas C-reactive protein correctly reclassified 3.4% of events. Results were similar in the 4128 men without evidence of angina, nitrate prescription, minor ECG abnormalities, or prior cerebrovascular disease.
Conclusion: N-terminal pro-B-type natriuretic peptide predicts CVD events in men without clinical evidence of CHD, angina, or history of stroke, and appears related more strongly to the risk for fatal events. N-terminal pro-B-type natriuretic peptide also provides moderate risk discrimination, in excess of that provided by the measurement of C-reactive protein.

Effect of B-type natriuretic peptide-guided treatment of chronic heart failure on total mortality and hospitalization: an individual patient meta-analysis

Richard W. Troughton, Christopher M. Frampton, Hans-Peter Brunner-La Rocca,
Matthias Pfisterer, Luc W.M. Eurlings, Hans Erntell, Hans Persson, et al.
Eur Heart J 2014; 35: 1559–1567 http://dx.doi.org:/10.1093/eurheartj/ehu090

Aims Natriuretic peptide-guided (NP-guided) treatment of heart failure has been tested against standard clinically guided care in multiple studies, but findings have been limited by study size. We sought to perform an individual patient data metaanalysis to evaluate the effect of NP-guided treatment of heart failure on all-cause mortality.
Methods and results
Eligible randomized clinical trials were identified from searches of Medline andEMBASEdatabases and the Cochrane Clinical
Trials Register. The primary pre-specified outcome, all-cause mortality was tested using a Cox proportional hazards regression model that included study of origin, age (< 75 or ≥75 years), and left ventricular ejection fraction (LVEF, ≤45 or .45%) as covariates. Secondary endpoints included heart failure or cardiovascular hospitalization. Of 11 eligible studies, 9 provided individual patient data and 2 aggregate data. For the primary endpoint individual data from 2000 patients were included, 994 randomized to clinically guided care and 1006 to NP-guided care. All-cause mortality was significantly reduced by NP-guided treatment [hazard ratio = 0.62 (0.45–0.86);
P = 0.004] with no heterogeneity between studies or interaction with LVEF. The survival benefit from NP-guided therapy was seen in younger ( <75 years) patients [0.62 (0.45–0.85); P = 0.004] but not older (≥75 years) patients [0.98 (0.75–1.27); P = 0.96]. Hospitalization due to heart failure [0.80 (0.67–0.94); P = 0.009] or cardiovascular disease [0.82 (0.67–0.99); P = 0.048]was significantly lower in NP-guided patients with no heterogeneity between studies and no interaction with age or LVEF.
Conclusion: Natriuretic peptide-guided treatment of heart failure reduces all-cause mortality in patients aged < 75 years and overall reduces heart failure and cardiovascular hospitalization.

Diagnostic and prognostic evaluation of left ventricular systolic heart failure by plasma N-terminal pro-brain natriuretic peptide concentrations in a large sample of the general population

B A Groenning, I Raymond, P R Hildebrandt, J C Nilsson, M Baumann, F Pedersen
Heart 2004;90:297–303. http://dx.doi.org:/10.1136/hrt.2003.026021

Objective: To evaluate N-terminal pro-brain natriuretic peptide (NT-proBNP) as a diagnostic and prognostic marker for systolic heart failure in the general population.
Design: Study participants, randomly selected to be representative of the background population, filled in a heart failure questionnaire and underwent pulse and blood pressure measurements, electrocardiography, echocardiography, and blood sampling and were followed up for a median (range) period of 805 (6021171) days.
Setting: Participants were recruited from four randomly selected general practitioners and were examined in a Copenhagen university hospital.
Patients: 382 women and 290 men in four age groups (50259 (n = 174); 60269 (n = 204); 70279 (n = 174); > 80 years (n = 120)).
Main outcome measures: Value of NT-proBNP in evaluating patients with symptoms of heart failure and impaired left ventricular (LV) systolic function; prognostic value of NT-proBNP for mortality and hospital admissions.
Results: In 38 (5.6%) participants LV ejection fraction (LVEF) was (40%. NT-proBNP identified patients with symptoms of heart failure and LVEF (40% with a sensitivity of 0.92, a specificity of 0.86, positive and negative predictive values of 0.11 and 1.00, and area under the curve of 0.94. NT-proBNP was the strongest independent predictor of mortality (hazard ratio (HR) = 5.70, p = 0.0001), hospital admissions for heart failure (HR = 13.83, p = 0.0001), and other cardiac admissions (HR = 3.69, p = 0.0001). Mortality (26 v 6, p = 0.0003), heart failure admissions (18 v 2, p = 0.0002), and admissions for other cardiac causes (44 v 13, p = 0.0001) were significantly higher in patients with NTproBNP above the study median (32.5 pmol/l). Conclusions: Measurement of NT-proBNP may be useful as a screening tool for systolic heart failure in the general population.

Copeptin—Marker of Acute Myocardial Infarction

Martin Möckel & Julia Searle
Curr Atheroscler Rep 2014; 16:421 http://dx.doi.org:/10.1007/s11883-014-0421-5

The concentration of copeptin, the C-terminal part of pro-arginine vasopressin, has been shown to increase early after acute and severe events. Owing to complementary pathophysiology and kinetics, the unspecific marker copeptin, in combination with highly cardio-specific troponin, has been evaluated as an early-rule-out strategy for acute myocardial infarction in patients presenting with signs and symptoms of acute coronary syndrome. Overall, most studies have reported a negative predictive value between 97 and 100 % for the diagnosis of acute myocardial infarction in low- to intermediate-risk patients with suspected acute coronary syndrome. Additionally, a recent multicenter, randomized process study, where patients who tested negative for copeptin and troponin were discharged from the emergency department, showed that the safety of the new process was comparable to that of the current standard process. Further interventional trials and data from registries are needed to ensure the effectiveness and patient benefit of the new strategy.

The role of copeptin as a diagnostic and prognostic biomarker for risk stratification in the emergency department

Christian H Nickel1, Roland Bingisser and Nils G Morgenthaler
BMC Medicine 2012, 10:7 http://www.biomedcentral.com/1741-7015/10/7

The hypothalamic-pituitary-adrenal axis is activated in response to stress. One of the activated hypothalamic hormones is arginine vasopressin, a hormone involved in hemodynamics and osmoregulation. Copeptin, the C-terminal part of the arginine vasopressin precursor peptide, is a sensitive and stable surrogate marker for arginine vasopressin release. Measurement of copeptin levels has been shown to be useful in a variety of clinical scenarios, particularly as a prognostic marker in patients with acute diseases such as lower respiratory tract infection, heart disease and stroke. The measurement of copeptin levels may provide crucial information for risk stratification in a variety of clinical situations. As such, the emergency department appears to be the ideal setting for its potential use. This review summarizes the recent progress towards determining the prognostic and diagnostic value of copeptin in the emergency department.

Variability of the Transferrin Receptor 2 Gene in AMD

Daniel Wysokinski, Janusz Blasiak, Mariola Dorecka, Marta Kowalska, et al.
Disease Markers 2014, Article ID 507356, 8 pages http://dx.doi.org/10.1155/2014/507356

Oxidative stress is a major factor in the pathogenesis of age-related macular degeneration (AMD). Iron may catalyze the Fenton reaction resulting in overproduction of reactive oxygen species. Transferrin receptor 2 plays a critical role in iron homeostasis and variability in its gene may influence oxidative stress and AMD occurrence. To verify this hypothesis we assessed the association between polymorphisms of the TFR2 gene and AMD. A total of 493AMDpatients and 171matched controls were genotyped for the two polymorphisms of the TFR2 gene: c.1892C>T (rs2075674) and c.−258+123T>C (rs4434553). We also assessed the modulation of some AMD risk factors by these polymorphisms.The CC and TT genotypes of the c.1892C>T were associated with AMD occurrence but the latter only in obese patients. The other polymorphism was not associated with AMD occurrence, but the CC genotype was correlated with an increasing AMD frequency in subjects with BMI < 26. The TT genotype and the T allele of this polymorphism decreased AMD occurrence in subjects above 72 years, whereas the TC genotype and the C allele increased occurrence of AMD in this group.The c.1892C>T and c.−258+123T>C polymorphisms of the TRF2 gene may be associated with AMD occurrence, either directly or by modulation of risk factors.

Urinary N-Acetyl-beta-D-glucosaminidase as an Early Marker for Acute Kidney Injury in Full-Term Newborns with Neonatal Hyperbilirubinemia

Bangning Cheng, Y Jin, G Liu, Z Chen, H Dai, and M Liu
Disease Markers 2014, Article ID 315843, 6 pages http://dx.doi.org/10.1155/2014/315843

Purpose. To investigate renal function estimated by markers in full-term newborns with hyperbilirubinemia.
Methods. A total of 332 full-term newborns with hyperbilirubinemia and 60 healthy full-term newborns were enrolled. Total serum bilirubin, serum creatinine (Cr), serum blood urea nitrogen (BUN), serum cystatin C (Cys-C), urinary beta-2-microglobulin (𝛽2MG) index, and urinary N-acetyl-beta-D-glucosaminidase (NAG) index were measured before and after treatment. All newborns were divided into three groups according to total serum bilirubin levels: group 1 (221-256), group 2 (256-342), and group 3 (>342). Results. The control group and group 1 did not differ significantly in regard to serum Cr, serum BUN, serum Cys-C, urinary 𝛽2MG index, and urinary NAG index. Urinary NAG index in group 2 was significantly higher than that in control group (𝑃 < 0.001). Between control group and group 3, serum Cys-C, urinary 𝛽2MG index, and urinary NAG index differed significantly. The significant positive correlation between total serum bilirubin and urinary NAG index was found in newborns when total serum bilirubin level was more than 272 𝜇mol/L.
Conclusions. High unconjugated bilirubin could result in acute kidney injury in full-term newborns. Urinary NAG might be the suitable marker for predicting acute kidney injury in full-term newborns with hyperbilirubinemia.

Urinary C-peptide creatinine ratio detects absolute insulin deficiency in Type 2 diabetes.

S V Hope, A G Jones, E Goodchild, M Shepherd, R E J Besser, B Shields, T McDonald, B A Knight, A Hattersley

Department of Geriatrics, Royal Devon and Exeter NHS Foundation Trust; NIHR Exeter Clinical Research Facility, University of Exeter.

Diabetic Medicine (impact factor: 2.9). 05/2013; http://dx.doi.org:/10.1111/dme.12222

Source: PubMed

ABSTRACT AIMS: To determine the prevalence and clinical characteristics of absolute insulin deficiency in long-standing Type 2 diabetes, using a strategy based on home urinary C-peptide creatinine ratio measurement.
METHODS: We assessed the urinary C-peptide creatinine ratios, from urine samples taken at home 2 h after the largest meal of the day, in 191 insulin-treated subjects with Type 2 diabetes (diagnosis age ≥45 years, no insulin in the first year). If the initial urinary C-peptide creatinine ratio was ≤0.2 nmol/mmol (representing absolute insulin deficiency), the assessment was repeated. A standardized mixed-meal tolerance test with 90-min stimulated serum C-peptide measurement was performed in nine subjects with a urinary C-peptide creatinine ratio ≤ 0.2 nmol/mmol (and in nine controls with a urinary C-peptide creatinine ratio >0.2 nmol/mmol) to confirm absolute insulin deficiency.
RESULTS: A total of 2.7% of participants had absolute insulin deficiency confirmed by a mixed-meal tolerance test. They were identified initially using urinary C-peptide creatinine ratio: 11/191 subjects (5.8%) had two consistent urinary C-peptide creatinine ratios ≤ 0.2 nmol/mmol; 9/11 subjects completed a mixed-meal tolerance test and had a median stimulated serum C-peptide of 0.18nmol/l. Five out of nine subjects had stimulated serum C-peptide <0.2 nmol/l and 9/9 subjects with urinary C-peptide creatinine ratio >0.2 had endogenous insulin secretion confirmed by the mixed-meal tolerance test. Compared with subjects with a urinary C-peptide creatinine ratio >0.2 nmol/mmol, those with confirmed absolute insulin deficiency had a shorter time to insulin treatment (median 2.5 vs. 6 years, P=0.005) and lower BMI (25.1 vs. 29.1kg/m(2) , P=0.04). Two out of five patients were glutamic acid decarboxylase autoantibody-positive.
CONCLUSIONS: Absolute insulin deficiency may occur in long-standing Type 2 diabetes, and cannot be reliably predicted by clinical features or autoantibodies. Its recognition should help guide treatment, education and management. The urinary C-peptide creatinine ratio is a practical non-invasive method to aid detection of absolute insulin deficiency, with a urinary C-peptide creatinine ratio > 0.2 nmol/mmol being a reliable indicator of retained endogenous insulin secretion.

Unlocking Biomarkers’ Full Potential

David Daniels, Ph.D. genengnews Feb 1, 2013 (Vol. 33, No. 3)

http://www.genengnews.com/gen-articles/unlocking-biomarkers-full-potential/4700/

Biomarker research and development has evolved over the past years from looking for a single marker (e.g., PSA) linked to a disease state to looking for a panel of markers that can capture the heterogeneity inherent in both the disease and the impacted patient population.

That is one of the key messages to be delivered at GTC’s “Biomarkers Summit” next month. Across the board, resources are being focused on the delivery of more precise, quantifiable biomarkers with predictive value in therapeutic decisions and for the prognosis of illness.

“Our focus on biomarker development is the recognition that the new products need to provide cost savings for the already strapped healthcare systems rather than just be cost effective,” shares Paul Billings, M.D., Ph.D., CMO at Life Technologies.

“We have built a new medical sciences group to address the needs of the multiple delivery systems in the world—from the sophisticated medical clinics in the developed world to the nurse-run shanty clinic in the third world. Providing tools for equitable access to quality diagnosis, on assay platforms that can provide care for all patients, is our goal.”

Life Tech’s medical sciences division has been built by acquisition of Pinpoint Genomics, Navigenics, and Compendia, and collaborations with partners such as Ingenuity Systems and CollabRx. The division is focused on taking the tools that have been used in the life science laboratories and providing molecular diagnostic data to the clinic. The intent is to deliver data in a valuable format that can be used by the molecular pathologist or the treating physician.

The division is developing the Pervenio™ Lung RS assay, a 14-gene expression profile that serves as a risk stratifier that uses a weighted algorithm for the expressed biomarkers within the tumor biopsy, a first-of-its-kind prognostic test for lung cancer, the firm reports.

Initially, tests will be offered as a service through Life Tech’s CLIA laboratory. Then, from the performance lessons learned, Life Tech’s will develop a simpler assay platform, with FDA approval, that can be dispersed globally without reduction of the essential content in the biomarker panel. The focus is on the workflow—screening for known mutations using established easy-to-use assay platforms, like RT-PCR. Should the screen not produce useful results, clinicians can search for new mutations via discovery platforms like next-gen sequencing (NGS).

http://www.genengnews.com/Media/images/Article/thumb_Sequenom_LungCartaPanel1722631391.jpg

Sequenom’s LungCarta panel of 214 somatic mutations in 26 tumor suppressors and oncogenes covers highly mutated pathways in lung adenocarcinomas.

At Sequenom, the company provides both the tools (DNA mass spectrometry and reagents) for confirmatory biomarker development as well as serving on the front lines as a diagnostic service provider (CLIA lab). The beauty of DNA mass spec is that it can process multiplexed PCR samples (10–60 loci) in a method that is quantitative when used for profiling tumor biopsies that are either archival or fresh tissue.

Given a tumor sample with multiple somatic mutations, the instrument enables the determination of the homogeneity of the cells, in which case the mutations will have the same allele frequency. Accuracy, as measured by coefficient of variance, is less than 2%. Despite this level of sensitivity, the mass spec can only be used as a confirmatory tool looking for known mutations. Discovery is best done using DNA sequencing. DNA mass spec can also be used to study methylation in tumor samples.

“In the not-too-distant future, we will be looking for mutations in plasma samples rather than biopsies,” predicts Charles Cantor, Ph.D., CSO at Sequenom.

“The key is to look noninvasively for mutations within plasma samples such that we can potentially catch the disease state earlier, rather than after tumor formation. Regardless of the tumor type, this approach will enable us to monitor therapeutic response and metastatic potential noninvasively. DNA mass spec is an ultrasensitive detection product that can detect somatic mutations at levels of 1 per 1,000. This level of sensitivity is critical for the future of plasma screening. NGS technology is not that sensitive.”

Sequenom’s CLIA lab is using automated DNA mass spec to provide three different test protocols: (1) carrier screening for cystic fibrosis looking at more than 100 different mutations, (2) adult macular degeneration progression using an SNP test with 13 loci, and (3) a noninvasive test for Rh compatibility between a mother and her unborn fetus.

http://www.genengnews.com/Media/images/Article/thumb_Illumina_HiSeq_Scientist2141841107.jpg

Scientists are using Illumina’s HiSeq system to discover molecular biomarkers that may provide opportunities for early detection of a range of diseases.

Sequenom has also set up an NGS facility within a CLIA lab in San Diego using Illumina’s HiSEQ platform. The NGS platform has been set up for noninvasive aneuploidy detection of maternal plasma (10 cc sample) looking at chromosomes 13, 18, and 21. The lab says it has analyzed more than 40,000 samples this year and is planning to increase that volume up to 100,000 samples per year. Most of these samples come from the U.S., but given the development of a new blood collection tube that allows for 72-hour ambient shipping, the lab is looking to increase the number of samples from outside the U.S.

Drug Development

During drug development, biomarkers function as pharmacodynamic markers to help assess the mechanism of action of a drug candidate, to define the downstream biological pathway, and to determine whether the drug is engaging the target with the anticipated biological effect. Later, biomarkers help determine whether a drug is effective using the tested regime (route of delivery, dosage level, and length of exposure time).

Following early development, the second stage is to use biomarkers to help segment patients for clinical trials. Part of the consideration here is how heterogeneous the disease is; are there homogeneous subsets of patients that will respond differentially to the drug based on different mechanisms of the disease?

“Biomarker research is focused on on- target effects,” says Nick Dracopoli, Ph.D., vp, head of oncology biomarkers at Janssen Research and Development, a J&J company.

“We look at indications and at patients with those indications that are most likely to respond to the drug candidates we’re developing. For oncology biomarkers, germ-line effects are weaker indicators than somatic changes in the tumor. As a consequence, SNP-based, genome-wide association studies are not very useful. It is better to focus on molecular changes within the tumor and define gene expression profiles and epigenetic modifications that correlate with the tumor phenotype. We are increasingly tracking patient immune response, particularly as more immuno-oncology products are moving into the drug development pipeline.”

The number of biomarkers being developed varies from project to project. But it is very clear that to be successful in the clinic, the biomarkers and the assays need to be of low complexity. Of the 10 to 12 companion diagnostics that have been approved by the FDA to date, all measure the status of the drug target (on-target markers). For example, EGFR measures the level of receptor expression; Braf and Kras markers measure the presence of the mutation and translocation in the ALK gene measures gene knockout.

It is important to realize that molecular profiles for first-in-class drugs are not optimal because they are based on only a few patients. Consequently they have weak predictive value overall.

“Aside from that rule of thumb, if you have a greater than 50% response rate for your drug, it is unlikely that you need a biomarker to predict response. Biomarker utility is best for drugs that would have a difficult road to approval, where it is critical to enrich for the subpopulation of responders. For example, Pfizer’s crizontinib was approved for non-small-cell lung patients but is only effective for 5% of all patients. If Pfizer was unable to demonstrate the relationship between activation of the ALK gene and disease, this inhibitor would not have been approved,” says Dr. Dracopoli.

“Drugs that are more broadly active can come to market without a companion diagnostic test. There is always a balance between the predictive values of the biomarker test and the response rates to treatment. That is, we should not treat if the chance of response is only 3–5%, rather than if it were 50% where the patient would want to take the chance if the drug were safe.”

An important take-home message is that mutations are not unique to an indication. So if you find a driver mutation in indications for which the drug has not been approved, you could discover new indications for the drug.

“At the end of the day, this is what cancer is—heterogeneous,” says Dr. Dracopoli. “We’d all love to treat one cancer with one drug and at one dose, but the story is more complex. The future of oncology is around understanding the molecular heterogeneity or underlying molecular pathology of the disease and the diversity of it, and then treat each patient accordingly.”

Clinical Considerations

“Given the complexity of biology,” says Achim Plum, Ph.D., principal consultant, Siemens, “whether is it cancer, metabolic disease, or any other disease state, we have been forced to move away from the idea that a single biomarker can capture the entire ‘story’ or mechanistic view of any disease. Hence newly developed biomarkers will be made up of a panel of markers that serve as a profile. In addition, with the sheer volume of DNA and protein analytics data, the clinic will need to employ software tools and algorithms to help the decision making.”

The task of getting broad profiling technologies that are analytical into a clinical setting and making them routine is difficult but not insurmontable. This will take a collaborative effort, something that Siemens among others are looking to develop. The key is to avoid technology hype and to establish good reliable software to process the data for decision making. “Data is not knowledge, and knowledge is not automatically decision making.”

As an academic, Daniel Chan, Ph.D., has a view of the whole value chain for biomarkers from discovery to development to use in the clinic. Dr. Chan holds the titles of professor in pathology, oncology, radiology, and urology, and is the director of the clinical chemistry division lab at Johns Hopkins Hospital.

Given his perspective from discovery to clinical use, Dr. Chan indicated that from the clinical point of view, “we need more markers.” He oversees the discovery of new biomarkers in his research lab, their validation in his translational research lab, and finally their utility in practice in his clinical chemistry lab. He is a strong advocate for collaboration of biomarker development from discovery to verification and validation to incorporation within the clinical practice.

Beyond the use of biomarkers for patient stratification and correlation between marker and therapeutic choice, as is the focus of the biopharma industry, for the clinic the use of biomarkers is for prevention and early detection. The earlier the detection, the better the outcome. That is, provide the “cure” before you need to initiate treatment.

To be successful in the future of biomarkers, we need to look beyond the biopharma focus and expand the horizon for early detection and monitor therapy later, says Dr. Chan. He describes a roadmap of developing bridges (to bridge the knowledge gaps), gates (decision gates for go/no go decisions as to whether a development path is viable), and partnerships (to collaborate with different points of view) for efficient new biomarker development.

According to Dr. Chan, we must define the intended use of the biomarker, which identifies the specific application and sets up the clinical study and study population to meet the clinical needs. We need to define specific assays to monitor biomarkers that will work within a clinical setting, not a research lab setting that uses disease models (tissue culture cells or small animals) and not real patient samples.

“The days when single markers are sufficient (PSA for prostate cancer or troponin for cardiovascular disease) are behind us. We need to develop a panel of markers or a profile pattern to address patient population heterogeneity and disease complexity that will guide our decision-making process,” remarks Dr. Chan. “Molecular biomarkers are giving way to protein biomarkers,” he adds.

Prevention and early detection will require the use of whole-body scans, so the sampling technology and analytical tools to be developed are critical to realize this goal. Assay ease of use, automation, and analytical performance that is suitable for the clinical lab are fundamental.

“An important future goal for biomarkers,” says Dr. Billings, “is to sample circulating tumor cells or circulating DNA in blood or plasma samples as a noninvasive measure of patient status. A decline in tumor biomarkers during chemotherapy, for example, could reflect the efficacy of the therapy. In contrast, an increase in tumor biomarkers, in a patient who had previously undergone surgery and therapy, might indicate disease recurrence, and is likely to do so before a tumor mass is detectable by imaging methods.”

STAT4 Gene Polymorphisms Are Associated with Susceptibility and ANA Status in Primary Biliary Cirrhosis

Satoru Joshita, T Umemura, M Nakamura, Y Katsuyama, S Shibata, et al.
Disease Markers 2014, Article ID 727393, 8 pages http://dx.doi.org/10.1155/2014/727393

Recent genome-wide association studies suggest that genetic factors contribute to primary biliary cirrhosis (PBC) susceptibility. Although several reports have demonstrated that the interleukin (IL) 12 signaling pathway is involved in PBC pathogenesis, its precise genetic factors have not been fully clarified. Here, we performed an association analysis between IL12A, IL12RB, and signal transducer and activator of transcription 4 (STAT4) genetic variations and susceptibility to PBC. Single nucleotide polymorphisms (SNPs) were genotyped in 395 PBC patients and 458 healthy subjects of Japanese ethnicity and evaluated for associations with PBC susceptibility, anti-nuclear antibody (ANA) status, and anti-mitochondrial antibody (AMA) status. We detected significant associations with PBC susceptibility for several STAT4 SNPs (rs10168266; p = 9.4 × 10−3, rs11889341; p = 1.2 × 10−3, rs7574865; p = 4.0 × 10−4, rs8179673; p = 2.0 × 10−4, and rs10181656; p = 4.2 × 10−5). Three risk alleles (rs7574865; p = 0.040, rs8179673; p = 0.032, and rs10181656; p = 0.031) were associated with ANA status, but not with AMA positivity. Our findings confirm that STAT4 is involved in PBC susceptibility and may play a role in ANA status in the Japanese population.

Serum Omentin-1 as a Disease Activity Marker for Crohn’s Disease

Yan Lu, Li Zhou, L Liu, Yan Feng, Li Lu, X Ren, X Dong, & W Sang
Disease Markers 2014, Article ID 162517, 5 pages http://dx.doi.org/10.1155/2014/162517

Background and Aim. It remains challenging to determine the inflammatory activity in Crohn’s disease (CD) for lack of specific laboratory markers. Recent studies suggest that serum omentin-1 is associated with inflammatory response. We aimed to assess the potential of serum omentin-1 as a marker of disease activity in CD patients.
Methods. Serum omentin-1 concentrations were determined by enzyme-linked immunosorbent assay (ELISA) in patients with CD (n = 240), functional gastrointestinal disorders (FGDs, n = 120), and healthy controls (HC, n = 60) and evaluated for correlation with disease activity. Expression of omentin-1 in colonic tissues from patients with CD was also analyzed by real-time PCR and Western blotting. Serum omentin-1 levels as an activity index were evaluated using a receiver operating characteristic (ROC) curve.
Results. Serum omentin-1 concentrations were significantly decreased in active CD patients compared with patients in remission, FGDs, and HC (all p < 0.001). Expression of omentin-1 was decreased at mRNA and protein levels in inflamed colonic tissues in active CD than that in noninflamed colonic tissues. Serum omentin-1 levels were negatively correlated with disease activity in CD, better than C-reactive protein (CRP).
Conclusion. Our results indicate that serum and colonic omentin-1 expressions are decreased in active CD patients. The correlation of serum omentin-1 with disease activity in CD is superior to that of CRP. Serum omentin-1 is a potential marker for CD disease activity.
Serum Levels of Resistin, Adiponectin, and Apelin in Gastroesophageal Cancer Patients

Dorota Diakowska, K Markocka-Mdczka, P Szelachowski, and K Grabowski
Disease Markers 2014, Article ID 619649, 8 pages http://dx.doi.org/10.1155/2014/619649

The aim of the study was the investigation of relationship between cachexia syndrome and serum resistin, adiponectin, and apelin in patients with gastroesophageal cancer (GEC).
Material and Methods. Adipocytokines concentrations were measured in sera of 85 GEC patients and 60 healthy controls. They were also evaluated in tumor tissue and appropriate normal mucosa of 38 operated cancer patients.
Results. Resistin and apelin concentrations were significantly higher in GEC patients than in the controls. The highest resistin levels were found in cachectic patients and in patients with distant metastasis. Serum adiponectin significantly decreased in GEC patients with regional and distant metastasis. Serum apelin was significantly higher in cachectic patients than in the controls. Apelin was positively correlated with hsCRP level. Resistin and apelin levels increased significantly in tumor tissues. Weak positive correlations between adipocytokines levels in serum and in tumor tissue were observed.
Conclusions. Resistin is associated with cachexia and metastasis processes of GEC. Reduction of serum adiponectin reflects adipose tissue wasting in relation to GEC progression. Correlation of apelin with hsCRP can reflect a presumable role of apelin in systemic inflammatory response in esophageal and gastric cancer.

Serum Level of HER-2 Extracellular Domain in Iranian Patients with Breast Cancer: A Follow-up Study

Mehrnoosh Doroudchi, Abdolrasoul Talei, Helmout Modjtahedi, et al.
IJI 2005; 2(4): 191-200

Background: A soluble form of HER-2/neu extracellular domain (sHER-2) is reported to be released in the sera of metastatic breast cancer patients.
Objective: To measure the level of sHER-2 in sera of 115 breast cancer patients. Methods: Serial samples of 27 patients with metastasis, 18 non-metastatic patients, 15 patients in stage 0/I and 14 patients with accompanying benign breast disease were also included in this study.
Results: No significant difference was observed between sHER-2 level in the pre-operative sera of breast cancer patients and that of healthy individuals. Only 8 out of 27 patients whom later developed metastasis showed elevated levels of sHER-2 in their first serum sample. However, a trend of increase in the level of sHER-2 was observed in 14 (51.8%) of 27 metastatic sera before clinical diagnosis of the metastasis. A significant association between sHER-2 positive status and vascular invasion of the tumor was observed (P = 0.02). In addition, significant correlation of sHER-2 level with CEA (highest r = 0.74) and CA 15.3 (highest r = 0.74) tumor marker levels in the serial sera were observed. The mean time from sHER-2 positivity to tumor metastasis was calculated to be 98 days (range = 29-174). Conclusion: Our results indicate that a relatively high percentage of Iranian patients with breast cancer show an elevated level of sHER-2 in their sera before clinical diagnosis of the tumor metastasis. Therefore, measuring the level of this oncoprotein, not only helps physicians in monitoring the patients during HERCEPTIN therapy, but also can be helpful in choosing more aggressive treatments at the early satges of tumor metastasis.
B-type natriuretic peptide is a biomarker for pulmonary hypertension in preterm infants with bronchopulmonary dysplasia

Alain Cuna, Jegen Kandasamy, Naomi Fineberg, Brian Sims
Research and Reports in Neonatology 2013:3 33–36
http://dx.doi.org/10.2147/RRN.S42236

Background: B-type natriuretic peptide (BNP) is a cardiac biomarker useful in screening for pulmonary hypertension (PH) in adults. It is possible that BNP may also be useful in detecting PH among preterm infants with bronchopulmonary dysplasia (BPD).
Objective: To determine the utility of BNP for identification of PH among preterm infants with BPD.
Methods: We retrospectively identified preterm infants with BPD who underwent screening echocardiography for suspected PH and had serum BNP levels measured within 10 days before or after echocardiography. Eligible infants were classified based on echocardiographic diagnosis of either PH or no PH. Median and interquartile ranges (IQR) of BNP values were compared, and area under the curve (AUC) of receiver operator characteristic (ROC) analysis was used to determine the optimum threshold value for detection of PH.
Results: Twenty-five preterm infants with BPD (mean gestational age 26.5 ± 1.7 weeks, mean birth weight 747 ± 248 g) were identified. The median difference in days between echocardiography and BNP measurement was 1 day (IQR 0–3, range 0–10 days). Based on echocardiography, 16 were diagnosed with PH and nine without PH. No significant difference in terms of gestational age, birth weight, sex, race, or respiratory support was found between the two groups. Median (IQR) BNP values of those with PH were higher than those without PH (413 [212–1178] pg/mL versus 55 [21–84] pg/mL, P , 0.001). AUC of ROC analysis showed that a BNP value of 117 pg/mL had 93.8% sensitivity and 100% specificity for detecting PH.
Conclusion: BNP estimation may be useful for screening of PH in infants with BPD.

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Pharmacogenomics

Posted in Biological Networks, Biological Networks, Gene Regulation and Evolution, Biomarkers & Medical Diagnostics, Cancer and Current Therapeutics, Cancer Screening, Cardiovascular Pharmacogenomics, Cell Biology, Signaling & Cell Circuits, Coagulation Therapy and Internal Bleeding, Curation, Diabetes Mellitus, Diagnostics and Lab Tests, Disease Biology, Epigenetics and Cardiovascular Risks, Gene Regulation and Evolution, Genetics & Pharmaceutical, Hematology, HTN, Pharmacotherapy of Cardiovascular Disease, tagged Cancer - General, cardiovascular diseases, Genome Biology, Hypertension, olatelets, Personalized medicine, pharmacotherapeutics, Statins related myopathy, thromboembolic risk, type 2 DM on January 31, 2015| Leave a Comment »

Pharmacogenomics

Writer and Curator: Larry H. Bernstein, MD, FCAP

Implementation and utilization of genetic testing in personalized medicine

NS Abul-Husn, AO Obeng, SC Sanderson, O Gottesman, S A Scott
Pharmacogenomics and Personalized Medicine 2014:7 227–240
http://dx.doi.org/10.2147/PGPM.S48887

Clinical genetic testing began over 30 years ago with the availability of mutation detection for sickle cell disease diagnosis. Since then, the field has dramatically transformed to include gene sequencing, high-throughput targeted genotyping, prenatal mutation detection, preimplantation genetic diagnosis, population-based carrier screening, and now genome-wide analyses using microarrays and next-generation sequencing. Despite these significant advances in molecular technologies and testing capabilities, clinical genetics laboratories historically have been centered on mutation detection for Mendelian disorders. However, the ongoing identification of deoxyribonucleic acid (DNA) sequence variants associated with common diseases prompted the availability of testing for personal disease risk estimation, and created commercial opportunities for direct-to-consumer genetic testing companies that assay these variants. This germline genetic risk, in conjunction with other clinical, family, and demographic variables, are the key components of the personalized medicine paradigm, which aims to apply personal genomic and other relevant data into a patient’s clinical assessment to more precisely guide medical management. However, genetic testing for disease risk estimation is an ongoing topic of debate, largely due to inconsistencies in the results, concerns over clinical validity and utility, and the variable mode of delivery when returning genetic results to patients in the absence of traditional counseling. A related class of genetic testing with analogous issues of clinical utility and acceptance is pharmacogenetic testing, which interrogates sequence variants implicated in interindividual drug response variability. Although clinical pharmacogenetic testing has not previously been widely adopted, advances in rapid turnaround time genetic testing technology and the recent implementation of preemptive genotyping programs at selected medical centers suggest that personalized medicine through pharmacogenetics is now a reality. This review aims to summarize the current state of implementing genetic testing for personalized medicine, with an emphasis on clinical pharmacogenetic testing.

Pharmacogenomic knowledge gaps and educational resource needs among physicians in selected specialties

Katherine A Johansen Taber, Barry D Dickinson
Pharmacogenomics and Personalized Medicine 2014:7 145–162
http://dx.doi.org/10.2147/PGPM.S63715

Background: The use of pharmacogenomic testing in the clinical setting has the potential to improve the safety and effectiveness of drug therapy, yet studies have revealed that physicians lack knowledge about the topic of pharmacogenomics, and are not prepared to implement it in the clinical setting. This study further explores the pharmacogenomic knowledge deficit and educational resource needs among physicians.
Materials and methods: Surveys of primary care physicians, cardiologists, and psychiatrists were conducted.
Results: Few physicians reported familiarity with the topic of pharmacogenomics, but more reported confidence in their knowledge about the influence of genetics on drug therapy. Only a small minority had undergone formal training in pharmacogenomics, and a majority reported being unsure what type of pharmacogenomic tests were appropriate to order for the clinical situation. Respondents indicated that an ideal pharmacogenomic educational resource should be electronic and include such components as how to interpret pharmacogenomic test results, recommendations for prescribing, population subgroups most likely to be affected, and contact information for laboratories offering pharmacogenomic testing.
Conclusion: Physicians continue to demonstrate pharmacogenomic knowledge gaps, and are unsure about how to use pharmacogenomic testing in clinical practice. Educational resources that are clinically oriented and easily accessible are preferred by physicians, and may best support appropriate clinical implementation of pharmacogenomics.

Developing genomic knowledge bases and databases to support clinical management: current perspectives

Vojtech Huser, Murat Sincan, James J Cimino
Pharmacogenomics and Personalized Medicine 2014:7 275–283
http://dx.doi.org/10.2147/PGPM.S49904

Personalized medicine, the ability to tailor diagnostic and treatment decisions for individual patients, is seen as the evolution of modern medicine. We characterize here the informatics resources available today or envisioned in the near future that can support clinical interpretation of genomic test results. We assume a clinical sequencing scenario (germline whole-exome sequencing) in which a clinical specialist, such as an endocrinologist, needs to tailor patient management decisions within his or her specialty (targeted findings) but relies on a genetic counselor to interpret off-target incidental findings. We characterize the genomic input data and list various types of knowledge bases that provide genomic knowledge for generating clinical decision support. We highlight the need for patient-level databases with detailed lifelong phenotype content in addition to genotype data and provide a list of recommendations for personalized medicine knowledge bases and databases. We conclude that no single knowledge base can currently support all aspects of personalized recommendations and that consolidation of several current resources into larger, more dynamic and collaborative knowledge bases may offer a future path forward.

Tumor Heterogeneity: Mechanisms and Bases for a Reliable Application of Molecular Marker Design

Salvador J. Diaz-Cano
Int. J. Mol. Sci. 2012, 13, 1951-2011; http://dx.doi.org/10.3390/ijms13021951

Tumor heterogeneity is a confusing finding in the assessment of neoplasms, potentially resulting in inaccurate diagnostic, prognostic and predictive tests. This tumor heterogeneity is not always a random and unpredictable phenomenon, whose knowledge helps designing better tests. The biologic reasons for this intratumoral heterogeneity would then be important to understand both the natural history of neoplasms and the selection of test samples for reliable analysis. The main factors contributing to intratumoral heterogeneity inducing gene abnormalities or modifying its expression include: the gradient ischemic level within neoplasms, the action of tumor microenvironment (bidirectional interaction between tumor cells and stroma), mechanisms of intercellular transference of genetic information (exosomes), and differential mechanisms of sequence-independent modifications of genetic material and proteins. The intratumoral heterogeneity is at the origin of tumor progression and it is also the byproduct of the selection process during progression. Any analysis of heterogeneity mechanisms must be integrated within the process of segregation of genetic changes in tumor cells during the clonal expansion and progression of neoplasms. The evaluation of these mechanisms must also consider the redundancy and pleiotropism of molecular pathways, for which appropriate surrogate markers would support the presence or not of heterogeneous genetics and the main mechanisms responsible. This knowledge would constitute a solid scientific background for future therapeutic planning.

Systematic evaluation of connectivity map for disease indications

Jie Cheng, Lun Yang, Vinod Kumar and Pankaj Agarwal
Genome Medicine 2014, 6:95 http://genomemedicine.com/content/6/12/95

Background: Connectivity map data and associated methodologies have become a valuable tool in understanding drug mechanism of action (MOA) and discovering new indications for drugs. One of the key ideas of connectivity map (CMAP) is to measure the connectivity between disease gene expression signatures and compound-induced gene expression profiles. Despite multiple impressive anecdotal validations, only a few systematic evaluations have assessed the accuracy of this aspect of CMAP, and most of these utilize drug-to-drug matching to transfer indications across the two drugs.
Methods: To assess CMAP methodologies in a more direct setting, namely the power of classifying known drug-disease relationships, we evaluated three CMAP-based methods on their prediction performance against a curated dataset of 890 true drug-indication pairs. The disease signatures were generated using Gene Logic BioExpress system and the compound profiles were derived from the Connectivity Map database (CMAP, build 02, http://www.broadinstitute.org/CMAP/).
Results: The similarity scoring algorithm called eXtreme Sum (XSum) better than the standard Kolmogorov-Smirnov (KS) statistic in terms of the area under curve and can achieve a four-fold enrichment at 0.01, false positive rate level, with AUC = 2.2E-4, P value = 0.0035.
Conclusion: Connectivity map can significantly enrich true positive drug-indication pairs given an effective matching algorithm.

Pharmacogenetics of Statin-Induced Myopathy: A Focused Review of the Clinical Translation of Pharmacokinetic Genetic Variants

Jasmine A Talameh and Joseph P Kitzmiller
J Pharmacogenomics Pharmacoproteomics 2014, 5:2 http://dx.doi.org/10.4172/2153-0645.1000128

Statins are the most commonly prescribed drugs in the United States and are extremely effective in reducing major cardiovascular events in the millions of Americans with hyperlipidemia. However, many patients (up to 25%) cannot tolerate or discontinue statin therapy due to statin-induced myopathy (SIM). Patients will continue to experience SIM at unacceptably high rates or experience unnecessary cardiovascular events (as a result of discontinuing or decreasing their statin therapy) until strategies for predicting or mitigating SIM are identified. A promising strategy for predicting or mitigating SIM is pharmacogenetic testing particularly of pharmacokinetic genetic variants as SIM is related to statin exposure. Data is emerging on the association between pharmacokinetic genetic variants and SIM.
A current, critical evaluation of the literature on pharmacokinetic genetic variants and SIM for potential translation to clinical practice is lacking. This review focuses specifically on pharmacokinetic genetic variants and their association with SIM clinical outcomes. We also discuss future directions, specific to the research on pharmacokinetic genetic variants, which could speed the translation into clinical practice. For simvastatin, we did not find sufficient evidence to support the clinical translation of pharmacokinetic genetic variants other than SLCO1B1. However, SLCO1B1 may also be clinically relevant for pravastatin- and pitavastatin-induced myopathy, but additional studies assessing SIM clinical outcome are needed. CYP2D6*4 may be clinically relevant for atorvastatin-induced myopathy, but mechanistic studies are needed. Future research efforts need to incorporate statin-specific analyses, multi-variant analyses, and a standard definition of SIM. As the use of statins is extremely common and SIM continues to occur in a significant number of patients, future research investments in pharmacokinetic genetic variants have the potential to make a profound impact on public health.

Benefits of Pharmacogenetics in the Management of Hypertension

Clara Torrellas, Juan Carlos Carril and Ramón Cacabelos
J Pharmacogenomics Pharmacoproteomics 2014, 5:2 http://dx.doi.org/10.4172/2153-0645.1000126

Introduction: Hypertension, suffered by 35% of the population, stands out as the main risk factor for cardiovascular disorders with the highest death rate worldwide. Only a small number of patients with hypertension gets efficient control over blood pressure (BP) with appropriate drug therapy. harmacogenetics, as a tool to identify antihypertensive therapeutic response-associated polymorphisms, could help to reduce this problem.
Objectives: We present here an epidemiological study of the prevalence of hypertension and its pharmacological treatment to demonstrate the error rate that physicians can commit when the patient´s pharmacogenetic profile is unknown.
Method: The sample consisted of 1115 individuals of which 332 met criteria for hypertension. We recorded each patient´s drug prescription prior to their visit to EuroEspes Biomedical Research Center, and analyzed their pharmacogenetic profile.
Results: About 30% of patients were hypertensive, of whom only 40.4% were receiving an active ingredient for hypertension control. Among them, CYP3A4/5 and CYP2C9 were the major metabolizing enzymes. Antagonists of angiotensin II receptors, followed by calcium-blocking agents and beta-adrenergic antagonists were the most commonly-prescribed drug categories. However, 61% of hypertensive patients were not taking suitable antihypertensive agents for their metabolism according to their genetic idiosyncrasy. Furthermore, the highest error rate was determined for CYP2C9.
Conclusion: The introduction of changes in the management of hypertension in the Spanish population could be useful to promote the prevention and treatment of high blood pressure in a more efficient way. The integration of pharmacogenetic testing into routine clinical procedures could optimize the therapeutic response, guiding the physician in the choice of the correct antihypertensive drug and the correct dose. The control of BP arises as an area of particular interest in assessing the validity and utility of pharmacogenetic testing/intervention.

Pharmacogenomics Study of Clopidogrel by RFLP based Genotyping of CYP2C19 in Cardiovascular Disease Patients in North-East Population of India

Prasanthi SV, Vinayak S Jamdade, Nityanand B Bolshette, Ranadeep Gogoi and Mangala Lahkar
J Pharmacogenomics Pharmacoproteomics 2014, 5:3 http://dx.doi.org/10.4172/2153-0645.1000132

Introduction and Objective: Pharmacogenetics is a genetically determined variability in drug responses. The genes and their allelic variants which affect our response to drugs are the main routes in development of pharmacogenetics. Clopidogrel is an antiplatelet drug, used against athero-thrombotic events in cardiovascular patients. The objective of our study was to identify the CYP2C19 Single Nucleotide Polymorphisms, responsible for altering the metabolism of clopidogrel, at gene level. And to document the prevalence of CYP2C19 gene mutations in clopidogrel treated cardiovascular disease patients in Assam population, Guwahati Medical College & Hospital, in North- East India.
Patients and Methods: We have studied 60 patients who received clopidogrel from Gauhati medical college and hospital Assam. Genomic DNA was extracted by using Hipura blood genomic DNA extracting mini preparation kit by following the manufacturer’s instructions.RFLP analysis was done by DNA amplification which was carried out by using set of primers and resulting ampicons of CYP2C19*2;CYP2C19*3 and CYP2C19*17 were subjected for Restriction digestion with SmaI, BamHI and Lwe0I respectively.
Results: We found that CYP2C19*2 had allelic frequency of ~40% in Gauhati Medical College and Hospital, Assam, North East India. None of the samples were mutated with CYP2C19*3 andCYP2C19*17 allele. Other CYP2C19 variant alleles with reduced or absent enzymatic activity have been identified. Conclusion: We found that loss of functional allele CYP2C19*2 had higher carriage frequency; whereas, CYP2C19*3 and *17 alleles were not found in cardiovascular patients who were taking clopidogrel. Personalized therapy targeting patients who carry these genetic variants might help to improve the clinical outcome.

Role of cytochrome P450 genotype in the steps toward personalized drug therapy

Larisa H Cavallari, Hyunyoung Jeong, Adam Bress
Pharmacogenomics and Personalized Medicine 2011:4 123–136
http://dx.doi.org/10.2147/PGPM.S15497

Genetic polymorphism for cytochrome 450 (P450) enzymes leads to interindividual variability in the plasma concentrations of many drugs. In some cases, P450 genotype results in decreased enzyme activity and an increased risk for adverse drug effects. For example, individuals with the CYP2D6 loss-of-function genotype are at increased risk for ventricular arrhythmia if treated with usual does of thioridazine. In other cases, P450 genotype may influence the dose of a drug required to achieve a desired effect. This is the case with warfarin, with lower doses often necessary in carriers of a variant CYP2C9*2 or *3 allele to avoid supratherapeutic anticoagulation. When a prodrug, such as clopidogrel or codeine, must undergo hepatic biotransformation to its active form, a loss-of-function P450 genotype leads to reduced concentrations of the active drug and decreased drug efficacy. In contrast, patients with multiple CYP2D6 gene copies are at risk for opioid-related toxicity if treated with usual doses of codeine-containing analgesics. At least 25 drugs contain information in their US Food and Drug Administration-approved labeling regarding P450 genotype. The CYP2C9, CYP2C19, and CYP2D6 genes are the P450 genes most often cited. To date, integration of P450 genetic information into clinical decision making is limited. However, some institutions are beginning to embrace routine P450 genotyping to assist in the treatment of their patients. Genotyping for P450 variants may carry less risk for discrimination compared with genotyping for disease-associated variants. As such, P450 genotyping is likely to lead the way in the clinical implementation of pharmacogenomics. This review discusses variability in the CYP2C9, CYP2C19, and CYP2D6 genes and the implications of this for drug efficacy and safety.

Asthma pharmacogenetics and the development of genetic profiles for personalized medicine

Victor E Ortega, Deborah A Meyers, Eugene R Bleecker
Pharmacogenomics and Personalized Medicine 2015:8 9–22
http://dx.doi.org/10.2147/PGPM.S52846

Human genetics research will be critical to the development of genetic profiles for personalized or precision medicine in asthma. Genetic profiles will consist of gene variants that predict individual disease susceptibility and risk for progression, predict which pharmacologic therapies will result in a maximal therapeutic benefit, and predict whether a therapy will result in an adverse response and should be avoided in a given individual. Pharmacogenetic studies of the glucocorticoid, leukotriene, and β2-adrenergic receptor pathways have focused on candidate genes within these pathways and, in addition to a small number of genome-wide association studies, have identified genetic loci associated with therapeutic responsiveness. This review summarizes these pharmacogenetic discoveries and the future of genetic profiles for personalized medicine in asthma. The benefit of a personalized, tailored approach to health care delivery is needed in the development of expensive biologic drugs directed at a specific biologic pathway. Prior pharmacogenetic discoveries, in combination with additional variants identified in future studies, will form the basis for future genetic profiles for personalized tailored approaches to maximize therapeutic benefit for an individual asthmatic while minimizing the risk for adverse events.

Clinical application of high throughput molecular screening techniques for pharmacogenomics

Arun P Wiita, Iris Schrijver
Pharmacogenomics and Personalized Medicine 2011:4 109–121
http://dx.doi.org/10.2147/PGPM.S15302

Genetic analysis is one of the fastest-growing areas of clinical diagnostics. Fortunately, as our knowledge of clinically relevant genetic variants rapidly expands, so does our ability to detect these variants in patient samples. Increasing demand for genetic information may necessitate the use of high throughput diagnostic methods as part of clinically validated testing. Here we provide a general overview of our current and near-future abilities to perform large-scale genetic testing in the clinical laboratory. First we review in detail molecular methods used for high throughput mutation detection, including techniques able to monitor thousands of genetic variants for a single patient or to genotype a single genetic variant for thousands of patients simultaneously. These methods are analyzed in the context of pharmacogenomic testing in the clinical laboratories, with a focus on tests that are currently validated as well as those that hold strong promise for widespread clinical application in the near future. We further discuss the unique economic and clinical challenges posed by pharmacogenomic markers. Our ability to detect genetic variants frequently outstrips our ability to accurately interpret them in a clinical context, carrying implications both for test development and introduction into patient management algorithms. These complexities must be taken into account prior to the introduction of any pharmacogenomic biomarker into routine clinical testing.

Clinical implementation of RNA signatures for pharmacogenomic decision-making

Weihua Tang, Zhiyuan Hu, Hind Muallem, Margaret L Gulley
Pharmacogenomics and Personalized Medicine 2011:4 95–107
http://dx.doi.org/10.2147/PGPM.S14888

RNA profiling is increasingly used to predict drug response, dose, or toxicity based on analysis of drug pharmacokinetic or pharmacodynamic pathways. Before implementing multiplexed RNA arrays in clinical practice, validation studies are carried out to demonstrate sufficient evidence of analytic and clinical performance, and to establish an assay protocol with quality assurance measures. Pathologists assure quality by selecting input tissue and by interpreting results in the context of the input tissue as well as the technologies that were used and the clinical setting in which the test was ordered. A strength of RNA profiling is the array-based measurement of tens to thousands of RNAs at once, including redundant tests for critical analytes or pathways to promote confidence in test results. Instrument and reagent manufacturers are crucial for supplying reliable components of the test system. Strategies for quality assurance include careful attention to RNA preservation and quality checks at pertinent steps in the assay protocol, beginning with specimen collection and proceeding through the variousphases of transport, processing, storage, analysis, interpretation, and reporting. Specimen quality is checked by probing housekeeping transcripts, while spiked and exogenous controls serve as a check on analytic performance of the test system. Software is required to manipulate abundant array data and present it for interpretation by a laboratory physician who reports results in a manner facilitating therapeutic decision-making. Maintenance of the assay requires periodic documentation of personnel competency and laboratory proficiency. These strategies are shepherding genomic arrays into clinical settings to provide added value to patients and to the larger health care system.

Dysregulation of the homeobox transcription factor gene HOXB13: role in prostate cancer

Brennan Decker, Elaine A Ostrander
Pharmacogenomics and Personalized Medicine 2014:7 193–201
http://dx.doi.org/10.2147/PGPM.S38117

Prostate cancer (PC) is the most common noncutaneous cancer in men, and epidemiological studies suggest that about 40% of PC risk is heritable. Linkage analyses in hereditary PC families have identified multiple putative loci. However, until recently, identification of specific risk alleles has proven elusive. Cooney et al used linkage mapping and segregation analysis to identify a putative risk locus on chromosome 17q21-22. In search of causative variant(s) in genes from the candidate region, a novel, potentially deleterious G84E substitution in homeobox transcription factor gene HOXB13 was observed in multiple hereditary PC families. In follow-up testing, the G84E allele was enriched in cases, especially those with an early diagnosis or positive family history of disease. This finding was replicated by others, confirming HOXB13 as a PC risk gene. The HOXB13 protein plays diverse biological roles in embryonic development and terminally differentiated tissue. In tumor cell lines, HOXB13 participates in a number of biological functions, including coactivation and localization of the androgen receptor and FOXA1. However, no consensus role has emerged and many questions remain. All HOXB13 variants with a proposed role in PC risk are predicted to damage the protein and lie in domains that are highly conserved across species. The G84E variant has the strongest epidemiological support and lies in a highly conserved MEIS protein-binding domain, which binds cofactors required for activation. On the basis of epidemiological and biological data, the G84E variant likely modulates the interaction between the HOXB13 protein and the androgen receptor, as well as affecting FOXA1-mediated transcriptional programming. However, further studies of the mutated protein are required to clarify the mechanisms by which this translates into PC risk.

Patient selection and targeted treatment in the management of platinum-resistant ovarian cancer

Christopher P Leamon, Chandra D Lovejoy, Binh Nguyen
Pharmacogenomics and Personalized Medicine 2013:6 113–125
http://dx.doi.org/10.2147/PGPM.S24943

Ovarian cancer (OC) has the highest mortality rate of any gynecologic cancer, and patients generally have a poor prognosis due to high chemotherapy resistance and late stage disease diagnosis. Platinum-resistant OC can be treated with cytotoxic chemotherapy such as paclitaxel, topotecan, pegylated liposomal doxorubicin, and gemcitabine, but many patients eventually relapse upon treatment. Fortunately, there are currently a number of targeted therapies in development for these patients who have shown promising results in recent clinical trials. These treatments often target the vascular endothelial growth factor pathway (eg, bevacizumab and aflibercept), DNA repair mechanisms (eg, iniparib and olaparib), or they are directed against folate related pathways (eg, pemetrexed, farletuzumab, and vintafolide). As many targeted therapies are only effective in a subset of patients, there is an increasing need for the identification of response predictive biomarkers. Selecting the right patients through biomarker screening will help tailor therapy to patients and decrease superfluous treatment to those who are biomarker negative; this approach should lead to improved clinical results and decreased toxicities. In this review the current targeted therapies used for treating platinum-resistant OC are discussed. Furthermore, use of prognostic and response predictive biomarkers to define OC patient populations that may benefit from specific targeted therapies is also highlighted.

Pharmacogenetics in breast cancer: steps toward personalized medicine in breast cancer management

Sarah Rofaiel, Esther N Muo1, Shaker A Mousa
Pharmacogenomics and Personalized Medicine 2010:3 129–143
http://dx.dpi.org:/10.2147/PGPM.S10789

There is wide individual variability in the pharmacokinetics, pharmacodynamics, and tolerance to anticancer drugs within the same ethnic group and even greater variability among different ethnicities. Pharmacogenomics (PG) has the potential to provide personalized therapy based on individual genetic variability in an effort to maximize efficacy and reduce adverse effects. The benefits of PG include improved therapeutic index, improved dose regimen, and selection of optimal types of drug for an individual or set of individuals. Advanced or metastatic breast cancer is typically treated with single or multiple combinations of chemotherapy regimens including anthracyclines, taxanes, antimetabolites, alkylating agents, platinum drugs, vinca alkaloids, and others. In this review, the PG of breast cancer therapeutics, including tamoxifen, which is the most widely used therapeutic for the treatment of hormone-dependent breast cancer, is reviewed. The pharmacological activity of tamoxifen depends on its conversion by cytochrome P450 2D6 (CYP2D6) to its abundant active metabolite, endoxifen. Patients with reduced CYP2D6 activity, as a result of either their genotype or induction by the coadministration of other drugs that inhibit CYP2D6 function, produce little endoxifen and hence derive limited therapeutic benefit from tamoxifen; the same can be said about the different classes of therapeutics in breast cancer. PG studies of breast cancer therapeutics should provide patients with breast cancer with optimal and personalized therapy

Novel treatment strategies in triple-negative breast cancer: specific role of poly(adenosine diphosphate-ribose) polymerase inhibition

M William Audeh
Pharmacogenomics and Personalized Medicine 2014:7 307–316
http://dx.doi.org/10.2147/PGPM.S39765

Inhibitors of the poly(adenosine triphosphate-ribose) polymerase (PARP)-1 enzyme induce synthetic lethality in cancers with ineffective DNA (DNA) repair or homologous repair deficiency, and have shown promising clinical activity in cancers deficient in DNA repair due to germ-line mutation in BRCA1 and BRCA2. The majority of breast cancers arising in carriers of BRCA1 germ-line mutations, as well as half of those in BRCA2 carriers, are classified as triple-negative breast cancer (TNBC). TNBC is a biologically heterogeneous group of breast cancers characterized by the lack of immunohistochemical expression of the ER, PR, or HER2 proteins, and for which the current standard of care in systemic therapy is cytotoxic chemotherapy. Many “sporadic” cases of TNBC appear to have indicators of DNA repair dysfunction similar to those in BRCA-mutation carriers, suggesting the possible utility of PARP inhibitors in a subset of TNBC. Significant genetic heterogeneity has been observed within the TNBC cohort, creating challenges for interpretation of prior clinical trial data, and for the design of future clinical trials. Several PARP inhibitors are currently in clinical development in BRCA-mutated breast cancer. The use of PARP inhibitors in TNBC without BRCA mutation will require biomarkers that identify cancers with homologous repair deficiency in order to select patients likely to respond. Beyond mutations in the BRCA genes, dysfunction in other genes that interact with the homologous repair pathway may offer opportunities to induce synthetic lethality when combined with PARP inhibition.

Clinical potential of novel therapeutic targets in breast cancer: CDK4/6, Src, JAK/STAT, PARP, HDAC, and PI3K/AKT/mTOR pathways

Sarah R Hosford, Todd W Miller
Pharmacogenomics and Personalized Medicine 2014:7 203–215
http://dx.doi.org/10.2147/PGPM.S52762

Breast cancers expressing estrogen receptor α, progesterone receptor, or the human epidermal growth factor receptor 2 (HER2) proto-oncogene account for approximately 90% of cases, and treatment with antiestrogens and HER2-targeted agents has resulted in drastically improved survival in many of these patients. However, de novo or acquired resistance to antiestrogen and HER2-targeted therapies is common, and many tumors will recur or progress despite these treatments. Additionally, the remaining 10% of breast tumors are negative for estrogen receptor α, progesterone receptor, and HER2 (“triple-negative”), and a clinically proven tumor-specific drug target for this group has not yet been identified. Therefore, the identification of new therapeutic targets in breast cancer is of vital clinical importance. Preclinical studies elucidating the mechanisms driving resistance to standard therapies have identified promising targets including cyclin-dependent kinase 4/6, phosphoinositide 3-kinase, poly adenosine diphosphate–ribose polymerase, Src, and histone deacetylase. Herein, we discuss the clinical potential and status of new therapeutic targets in breast cancer.

Overview of diagnostic/targeted treatment combinations in personalized medicine for breast cancer patients

Anna Tessari, Dario Palmieri, Serena Di Cosimo
Pharmacogenomics and Personalized Medicine 2014:7 1–19
http://dx.doi.org/10.2147/PGPM.S53304

Breast cancer includes a body of molecularly distinct subgroups, characterized by different presentation, prognosis, and sensitivity to treatments. Significant advances in our understanding of the complex architecture of this pathology have been achieved in the last few decades, thanks to new biotechnologies that have recently come into the research field and the clinical practice, giving oncologists new instruments that are based on biomarkers and allowing them to set up a personalized approach for each individual patient. Here we review the main treatments available or in preclinical development, the biomolecular diagnostic and prognostic approaches that changed our perspective about breast cancer, giving an overview of targeted therapies that represent the current standard of care for these patients. Finally, we report some examples of how new technologies in clinical practice can set in motion the development of new drugs.

Human ABC transporter ABCG2/BCRP expression in chemoresistance: basic and clinical perspectives for molecular cancer therapeutics

Kohji Noguchi, Kazuhiro Katayama, Yoshikazu Sugimoto
Pharmacogenomics and Personalized Medicine 2014:7 53–64
http://dx.doi.org/10.2147/PGPM.S38295

Adenosine triphosphate (ATP)-binding cassette (ABC) transporter proteins, such as ABCB1/P-glycoprotein (P-gp) and ABCG2/breast cancer resistance protein (BCRP), transport various structurally unrelated compounds out of cells. ABCG2/BCRP is referred to as a “half-type” ABC transporter, functioning as a homodimer, and transports anticancer agents such as irinotecan, 7-ethyl-10-hydroxycamptothecin (SN-38), gefitinib, imatinib, methotrexate, and mitoxantrone from cells. The expression of ABCG2/BCRP can confer a multidrug-resistant phenotype on cancer cells and affect drug absorption, distribution, metabolism, and excretion in normal tissues, thus modulating the in vivo efficacy of chemotherapeutic agents. Clarification of the substrate preferences and structural relationships of ABCG2/BCRP is essential for our understanding of the molecular mechanisms underlying its effects in vivo during chemotherapy. Its single-nucleotide polymorphisms are also involved in determining the efficacy of chemotherapeutics, and those that reduce the functional activity of ABCG2/BCRP might be associated with unexpected adverse effects from normal doses of anticancer drugs that are ABCG2/BCRP substrates. Importantly, many recently developed molecular-targeted cancer drugs, such as the tyrosine kinase inhisbitors, imatinib mesylate, gefitinib, and others, can also interact with ABCG2/BCRP. Both functional single-nucleotide polymorphisms and inhibitory agents of ABCG2/BCRP modulate the in vivo pharmacokinetics and pharmacodynamics of these molecular cancer treatments, so the pharmacogenetics of ABCG2/BCRP is an important consideration in the application of molecular-targeted chemotherapies.

Bosutinib: a SRC–ABL tyrosine kinase inhibitor for treatment of chronic myeloid leukemia

Fuad El Rassi, Hanna Jean Khoury
Pharmacogenomics and Personalized Medicine 2013:6 57–62
http://dx.doi.org/10.2147/PGPM.S32145

Bosutinib is one of five tyrosine kinase inhibitors commercially available in the United States for the treatment of chronic myeloid leukemia. This review of bosutinib summarizes the mode of action, pharmacokinetics, efficacy and safety data, as well as the patient-focused perspective through quality-of-life data. Bosutinib has shown considerable and sustained efficacy in chronic myeloid leukemia, especially in the chronic phase, with resistance or intolerance to prior tyrosine kinase inhibitors. Bosutinib has distinct but manageable adverse events. In the absence of T315I and V299L mutations, there are no absolute contraindications for the use of bosutinib in this patient population.

Toward precision medicine with next-generation EGFR inhibitors in non-small-cell lung cancer
Timothy A Yap, Sanjay Popat
Pharmacogenomics and Personalized Medicine 2014:7 285–295
http://dx.doi.org/10.2147/PGPM.S55339

The use of genomics to discover novel targets and biomarkers has placed the field of oncology at the forefront of precision medicine. First-generation epidermal growth factor receptor (EGFR) inhibitors have transformed the therapeutic landscape of EGFR mutant non-small-cell lung carcinoma through the genetic stratification of tumors from patients with this disease. Somatic EGFR mutations in lung adenocarcinoma are now well established as predictive biomarkers of response and resistance to small-molecule EGFR inhibitors. Despite early patient benefit, primary resistance and subsequent tumor progression to first-generation EGFR inhibitors are seen in 10%–30% of patients with EGFR mutant non-small-cell lung carcinoma. Acquired drug resistance is also inevitable, with patients developing disease progression after only 10–13 months of antitumor therapy. This review details strategies pursued in circumventing T790M-mediated drug resistance to EGFR inhibitors, which is the most common mechanism of acquired resistance, and focuses on the clinical development of second-generation EGFR inhibitors, exemplified by afatinib (BIBW2992). We discuss the rationale, mechanism of action, clinical efficacy, and toxicity profile of afatinib, including the LUX-Lung studies. We also discuss the emergence of third-generation irreversible mutant-selective inhibitors of EGFR and envision the future management of EGFR mutant lung adenocarcinoma.

ALK-driven tumors and targeted therapy: focus on crizotinib

Carlos Murga-Zamalloa, Megan S Lim
Pharmacogenomics and Personalized Medicine 2014:7 87–94
http://dx.doi.org/10.2147/PGPM.S37504

Receptor tyrosine kinases have emerged as promising therapeutic targets for a diverse set of tumors. Overactivation of the tyrosine kinase anaplastic lymphoma kinase (ALK) has been reported in several types of malignancies such as anaplastic large cell lymphoma, inflammatory myofibroblastic tumor, neuroblastoma, and non-small-cell lung carcinoma. Further characterization of the molecular role of ALK has revealed an oncogenic signaling signature that results in tumor dependence on ALK. ALK-positive tumors display a different behavior than their ALK-negative counterparts; however, the specific role of ALK in some of these tumors remains to be elucidated. Although more studies are required to establish selective targeting of ALK as a definitive therapeutic option, initial trials have shown extraordinary results in the majority of cases.

Non-small-cell lung cancer: molecular targeted therapy and personalized medicine – drug resistance, mechanisms, and strategies

Marybeth Sechler, AD Cizmic, S Avasarala, M Van Scoyk, C Brzezinski, et al.
Pharmacogenomics and Personalized Medicine 2013:6 25–36
http://dx.doi.org/10.2147/PGPM.S26058

Targeted therapies for cancer bring the hope of specific treatment, providing high efficacy and in some cases lower toxicity than conventional treatment. Although targeted therapeutics have helped immensely in the treatment of several cancers, like chronic myelogenous leukemia, colon cancer, and breast cancer, the benefit of these agents in the treatment of lung cancer remains limited, in part due to the development of drug resistance. In this review, we discuss the mechanisms of drug resistance and the current strategies used to treat lung cancer. A better understanding of these drug-resistance mechanisms could potentially benefit from the development of a more robust personalized medicine approach for the treatment of lung cancer.

ERCC1 and XRCC1 as biomarkers for lung and head and neck cancer

Alec Vaezi, Chelsea H Feldman, Laura J Niedernhofer
Pharmacogenomics and Personalized Medicine 2011:4 47–63
http://dx.doi.org/10.2147/PGPM.S20317

Advanced stage non-small cell lung cancer and head and neck squamous cell carcinoma are both treated with DNA damaging agents including platinum-based compounds and radiation therapy. However, at least one quarter of all tumors are resistant or refractory to these genotoxic agents. Yet the agents are extremely toxic, leading to undesirable side effects with potentially no benefit. Alternative therapies exist, but currently there are no tools to predict whether the first-line genotoxic agents will work in any given patient. To maximize therapeutic success and limit unnecessary toxicity, emerging clinical trials aim to inform personalized treatments tailored to the biology of individual tumors. Worldwide, significant resources have been invested in identifying biomarkers for guiding the treatment of lung and head and neck cancer. DNA repair proteins of the nucleotide excision repair pathway (ERCC1) and of the base excision repair pathway (XRCC1), which are instrumental in clearing DNA damage caused by platinum drugs and radiation, have been extensively studied as potential biomarkers of clinical outcomes in lung and head and neck cancers. The results are complex and contradictory. Here we summarize the current status of single nucleotide polymorphisms, mRNA, and protein expression of ERCC1 and XRCC1 in relation
to cancer risk and patient outcomes.

Optimizing response to gefitinib in the treatment of non-small-cell lung cancer

Pietro Carotenuto, Cristin Roma, Anna Maria Rachiglio, Raffaella Pasquale, et al.
Pharmacogenomics and Personalized Medicine 2011:4 1–9
http://dx.doi.org:/10.2147/PGPM.S6626

The epidermal growth factor receptor (EGFR) is expressed in the majority of non-small-cell lung cancer (NSCLC). However, only a restricted subgroup of NSCLC patients respond to treatment with the EGFR tyrosine kinase inhibitor (EGFR TKI) gefitinib. Clinical trials have demonstrated that patients carrying activating mutations of the EGFR significantly benefit from treatment with gefitinib. In particular, mutations of the EGFR TK domain have been shown to increase the sensitivity of the EGFR to exogenous growth factors and, at the same time, to EGFR TKIs such as gefitinib. EGFR mutations are more frequent in patients with particular clinical and pathological features such as female sex, nonsmoker status, adenocarcinoma histology, and East Asian ethnicity. A close correlation was found between EGFR mutations and response to gefitinib in NSCLC patients. More importantly, randomized Phase III studies have shown the superiority of gefitinib compared with chemotherapy in EGFR mutant patients in the first-line setting. In addition, gefitinib showed a good toxicity profile with an incidence of adverse events that was significantly lower compared with chemotherapy. Therefore, gefitinib is a major breakthrough for the management of EGFR mutant NSCLC patients and represents the first step toward personalized treatment of NSCLC.

Pharmacogenomics of drug metabolizing enzymes and transporters: implications for cancer therapy

Jing Li, Martin H Bluth
Pharmacogenomics and Personalized Medicine 2011:4 11–33
http://dx.doi.org:/10.2147/PGPM.S18861

The new era of personalized medicine, which integrates the uniqueness of an Individual with respect to the pharmacokinetics and pharmacodynamics of a drug, holds promise as a means to provide greater safety and efficacy in drug design and development. Personalized medicine is particularly important in oncology, whereby most clinically used anticancer drugs have a narrow therapeutic window and exhibit a large interindividual pharmacokinetic and pharmacodynamics variability. This variability can be explained, at least in part, by genetic variations in the genes encoding drug metabolizing enzymes, transporters, or drug targets. Understanding of how genetic variations influence drug disposition and action could help in tailoring cancer therapy based on individual’s genetic makeup. This review focuses on the pharmacogenomics of drug metabolizing enzymes and drug transporters, with a particular highlight of examples whereby genetic variations in the metabolizing enzymes and transporters influence the pharmacokinetics and/or response of chemotherapeutic agents.

Transcriptome-wide signatures of tumor stage in kidney renal clear cell carcinoma: connecting copy number variation, methylation and transcription factor activity
Qi Liu, Pei-Fang Su, Shilin Zhao and Yu Shyr
Genome Medicine 2014, 6:117 http://genomemedicine.com/content/6/12/117

Background: Comparative analysis of expression profiles between early and late stage cancers can help to understand cancer progression and metastasis mechanisms and to predict the clinical aggressiveness of cancer. The observed stage-dependent expression changes can be explained by genetic and epigenetic alterations as well as transcription dysregulation. Unlike genetic and epigenetic alterations, however, activity changes of transcription factors, generally occurring at the post-transcriptional or post-translational level, are hard to detect and quantify.
Methods: Here we developed a statistical framework to infer the activity changes of transcription factors by simultaneously taking into account the contributions of genetic and epigenetic alterations to mRNA expression variations.
Results: Applied to kidney renal clear cell carcinoma (KIRC), the model underscored the role of methylation as a significant contributor to stage-dependent expression alterations and identified key transcription factors as potential drivers of cancer progression.
Conclusions: Integrating copy number, methylation, and transcription factor activity signatures to explain stage-dependent expression alterations presented a precise and comprehensive view on the underlying mechanisms during KIRC progression.

Developments in renal pharmacogenomics and applications in chronic kidney disease

Ariadna Padullés, Inés Rama, Inés Llaudó, Núria Lloberas
Pharmacogenomics and Personalized Medicine 2014:7 251–266
http://dx.doi.org/10.2147/PGPM.S52763

Chronic kidney disease (CKD) has shown an increasing prevalence in the last century. CKD encompasses a poor prognosis related to a remarkable number of comorbidities, and many patients suffer from this disease progression. Once the factors linked with CKD evolution are distinguished, it will be possible to provide and enhance a more intensive treatment to high-risk patients. In this review, we focus on the emerging markers that might be predictive or related to CKD progression physiopathology as well as those related to a different pattern of response to treatment, such as inhibitors of the renin–angiotensin system (including angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers; the vitamin D receptor agonist; salt sensitivity hypertension; and progressive kidney-disease markers with identified genetic polymorphisms). Candidate-gene association studies and genome-wide association studies have analyzed the genetic basis for common renal diseases, including CKD and related factors such as diabetes and hypertension. This review will, in brief, consider genotype-based pharmacotherapy, risk prediction, drug target recognition, and personalized treatments, and will mainly focus on findings in CKD patients. An improved understanding will smooth the progress of switching from classical clinical medicine to gene-based medicine.

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Proteomics

Posted in Amino acids, Ca2+ triggered activation, Cell Biology, Clinical Diagnostics, Coagulation Therapy and Internal Bleeding, Curation, Cytoskeleton, Diagnostics and Lab Tests, Disease Biology, Frontiers in Cardiology and Cardiovascular Disorders, Gene Regulation, Hematology, Ionic Transporters Na+, Mass automation of plasma proteins, Myocardial Metabolism, Neurodegenerative Diseases, Neurohumoral Transmission, Nitric Oxide in Health and Disease, Personalized and Precision Medicine & Genomic Research, Pharmaceutical Analytics, Pharmaceutical Discovery, Proteins, Proteomics, Rapid automation of plasma protein pools, Signaling & Cell Circuits, tagged Cancer - General, Cardiovascular disease, cell-cell interactions, Cytoskeleton, Proteomics, receptors on January 31, 2015| Leave a Comment »

Proteomics

Writer and Curator: Larry H. Bernstein, MD, FCAP

The previous discussion concerned genomics, metabolomics, and cancer. The discussion that follows is concerned with the expanding filed of proteomics, which has implication for disease discovery, pharmaceutical targeting, and diagnostics.

The human proteome – a scientific opportunity for transforming diagnostics, therapeutics, and healthcare

Marc Vidal, Daniel W Chan, Mark Gerstein, Matthias Mann, Gilbert S Omenn, et al.
Clinical Proteomics 2012, 9:6 http://www.clinicalproteomicsjournal.com/content/9/1/6

A National Institutes of Health (NIH) workshop was convened in Bethesda, MD on September 26–27, 2011, with representative scientific leaders in the field of proteomics and its applications to clinical settings. The main purpose of this workshop was to articulate ways in which the biomedical research community can capitalize on recent technology advances and synergize with ongoing efforts to advance the field of human proteomics. This executive summary and the following full report describe the main discussions and outcomes of the workshop.

Proteomics Pioneer Award 2013: Professor Amos Bairoch, University of Geneva, Switzerland

Eupa Open Proteomics 2 (2014) 34 http://dx.doi.org/10.1016/j.euprot.2013.12.002

Amos Bairoch has always been fascinated by computer science, genetics and biochemistry. His fi rst project, as a PhD student, was the development of PC/Gene, a MS-DOS based software package for the analysis of protein and nucleotide sequences. While working on this project, he realized that there was no single resource for protein sequences, and started to develop the first annotated protein sequence database, which became Swiss-Prot and was first released in July 1986. In 1988, he created PROSITE, a database of protein families and domains, and a little later ENZYME, an enzyme nomenclature database.

Amos Bairoch led the Swiss-Prot group from its creation in 1988 until 2009. During this period, Swiss-Prot became the primary protein sequence resource in the world and has been a key research instrument for both bioinformaticians and laboratory-based scientists, particularly in the field of proteomics.

Since 2009, Amos Bairoch’s group is developing neXtProt, a knowledgebase
specifically dedicated to human proteins.neXtProt has been chosen as the reference protein database for the HUPO Human Proteome Projects.

For his major contributions in the field of proteomic databases, Amos Bairoch received the Friedrich Miescher Award from the Swiss Society of Biochemistry in 1993, the Helmut Horten Foundation Incentive Award in 1995, the Pehr Edman award and the European Latsis Prize in 2004, the Otto Naegeli prize in 2010, and the HUPO Distinguished Achievement Award in Proteomic Sciences in 2011.

National Heart, Lung, and Blood Institute Clinical Proteomics Working Group Report

CB Granger, JE Van Eyk, SC Mockrin and N. Leigh Anderson
Circulation. 2004;109:1697-1703
http://dx.doi.org:/10.1161/01.CIR.0000121563.47232.2A

The National Heart, Lung, and Blood Institute (NHLBI) Clinical Proteomics Working Group was charged with identifying opportunities and challenges in clinical proteomics and using these as a basis for recommendations aimed at directly improving patient care. The group included representatives of clinical and translational research, proteomic technologies, laboratory medicine, bioinformatics, and 2 of the NHLBI Proteomics Centers, which form part of a program focused on innovative technology development. This report represents the results from a one-and-a-half-day meeting on May 8 and 9, 2003. For the purposes of this report, clinical proteomics is defined as the systematic, comprehensive, large-scale identification of protein patterns (“fingerprints”) of disease and the application of this knowledge to improve patient care and public health through better assessment of disease susceptibility, prevention of disease, selection of therapy for the individual, and monitoring of treatment response.

The -omics era: Proteomics and lipidomics in vascular research

Athanasios Didangelos, Christin Stegemann, Manuel Mayr
Atherosclerosis 221 (2012) 12– 17
http://dx.doi.org:/10.1016/j.atherosclerosis.2011.09.043

The retention of proatherogenic low-density lipoprotein (LDL) particles on the subendothelial extracellular matrix (ECM) is a hallmark of atherosclerosis. Apolipoprotein B (apoB)-containing lipoprotein particles are trapped in the arterial intima by proteoglycans in atherosclerosis-prone areas and eventually become modified, commonly by aggregation and oxidation. The initial accumulation of proatherogenic lipoproteins initiates an inflammatory response, which results in the release of proteolytic enzymes and induces the dedifferentiation of vascular smooth muscle cells (SMCs) resulting in alterations of their matrix producing properties. The precise mechanisms responsible for the accumulation of certain matrix components and subsequent lipoprotein retention on the vessel wall are not fully elucidated. Undoubtedly, ECM remodeling contributes to the formation of atherosclerotic lesions and the lipid composition of apolipoproteins influences their binding properties to the matrix. An unbiased discovery approach, which is not limited to known molecules of presumed importance, will be invaluable for the identification of novel, previously unknown mediators of disease. Although descriptive, the detailed examination of atherosclerotic plaques using advanced proteomics and lipidomics techniques can generate novel insights and form the basis for further mechanistic investigations.

The Revolution in Proteomics Ionization –
CaptiveSpray nanoBooster™
Bruker, LC-MS Source

Bruker CaptiveSpray principle:

Stable and robust nanoflow LC/MS is still a challenge in proteomics analysis. The Bruker CaptiveSpray source is a revolutionary ion source with a patented design that provides provides easy operation just as simple normal flow electrospray.

CaptiveSpray delivers nanospray sensitivity, resists plugging, and provides reproducible uninterrupted flow for even the most complex proteomics samples.

CaptiveSpray nanoBooster brings your MS to the next performance level and provides even higher flexibility.

Boost nanoflow sensitivity
• Push up ID rates
• Enabling Glycoanalysis
• Supercharging capability

CaptiveSpray provides a vortex gas that sweeps around the emitter spray tip to desolvate and to focus the Taylor cone into the MS inlet capillary. The vacuum seal to the MS ion guide draws all of the sample ions into the MS increasing the efficiency of sample transfer from the spray tip into the mass spectrometer. The direct connection to the inlet capillary eliminates the need for any source adjustment making the CaptiveSpray source truly Plug-and-Play.

CaptiveSpray Illustration

Structure elucidation

Tissue Proteomics for the Next Decade? Towards a Molecular Dimension in Histology

R Longuespee, M Fleron, C Pottier, F Quesada-Calvo, Marie-Alice Meuwis, et al.
OMICS A Journal of Integrative Biology 2014; 18(9)
http://dx.doi.org:/10.1089/omi.2014.0033

Currently, sampling methods, biochemical procedures, and MS instrumentations allow scientists to perform ‘‘in depth’’ analysis of the protein content of any type of tissue of interest. This article reviews the salient issues in proteomics analysis of tissues. We first outline technical and analytical considerations for sampling and biochemical processing of tissues and subsequently the instrumental possibilities for proteomics analysis such as shotgun proteomics in an anatomical context. Specific attention concerns formalin fixed and paraffin embedded (FFPE) tissues that are potential ‘‘gold mines’’ for histopathological investigations. In all, the matrix assisted laser desorption/ionization (MALDI) MS imaging, which allows for differential mapping of hundreds of compounds on a tissue section, is currently the most striking evidence of linkage and transition between ‘‘classical’’ and ‘‘molecular’’ histology. Tissue proteomics represents a veritable field of research and investment activity for modern biomarker discovery and development for the next decade.

A transcriptome-proteome integrated network identifies ERp57 as a hub that mediates bone metastasis

N Santana-Codina, R Carretero, R Sanz-Pamplona1, T Cabrera, et al.
The American Society for Biochemistry and Molecular Biology
MCP Apr 26, 2013; Manuscript M112.022772
E-mail: asierra@idibell.cat

Bone metastasis is the most common distant relapse in breast cancer. The identification of key proteins involved in the osteotropic phenotype would represent a major step toward the development of new prognostic markers and therapeutic improvements. The aim of this study was to characterize functional phenotypes that favor bone metastasis in human breast cancer.
We used the human breast cancer cell line MDA-MB-231 and its osteotropic BO2 subclone to identify crucial proteins in bone metastatic growth. We identified 31 proteins, 15 underexpressed and 16 overexpressed, in BO2 cells compared to parental cells. We employed a network-modeling approach in which these 31 candidate proteins were prioritized with respect to their potential in metastasis formation, based on the topology of the protein–protein interaction network and differential expression. The protein–protein interaction network provided a framework to study the functional relationships between biological molecules by attributing functions to genes whose functions had not been characterized.
The combination of expression profiles and protein interactions revealed an endoplasmic reticulum-thiol oxidoreductase, ERp57, functioning as a hub which retained 4 downregulated nodes involved in antigen presentation associated with the human major histocompatibility complex class I molecules, including HLA-A, HLA-B, HLA-E and HLA-F. Further analysis of the interaction network revealed an inverse correlation between ERp57 and vimentin, which influences cytoskeleton reorganization. Moreover, knockdown of ERp57 in BO2 cells confirmed its bone organ-specific prometastatic role. Altogether, ERp57 appears as a multifunctional chaperone that can regulate diverse biological processes to maintain the homeostasis of breast cancer cells and promote the development of bone metastasis.

Tandem-repeat protein domains across the tree of life

Kristin K. Jernigan and Seth R. Bordenstein
PeerJ 3:e732; 2015 http://dx.doi.org:/10.7717/peerj.732

Tandem-repeat protein domains, composed of repeated units of conserved stretches of 20–40 amino acids, are required for a wide array of biological functions. Despite their diverse and fundamental functions, there has been no comprehensive assessment of their taxonomic distribution, incidence, and associations with organismal lifestyle and phylogeny.
In this study, we assess for the first time the abundance of armadillo (ARM) and tetratricopeptide (TPR) repeat domains across all three domains in the tree of life and compare the results to our previous analysis on ankyrin (ANK) repeat domains in this journal. All eukaryotes and a majority of the bacterial and archaeal genomes analyzed have a minimum of one TPR and ARM repeat. In eukaryotes, the fraction of ARM-containing proteins is approximately double that of TPR and ANK-containing proteins, whereas bacteria and archaea are enriched in TPR-containing proteins relative to ARM- and ANK-containing proteins.
We show in bacteria that phylogenetic history, rather than lifestyle or pathogenicity, is a predictor of TPR repeat domain abundance, while neither phylogenetic history nor lifestyle predicts ARM repeat domain abundance. Surprisingly, pathogenic bacteria were not enriched in TPR-containing proteins, which have been associated within virulence factors in certain species. Taken together, this comparative analysis provides a newly appreciated view of the prevalence and diversity of multiple types of tandem-repeat protein domains across the tree of life.
A central finding of this analysis is that tandem repeat domain-containing proteins are prevalent not just in eukaryotes, but also in bacterial and archaeal species.

Detection of colorectal adenoma and cancer based on transthyretin and C3a-desArg serum levels

Anne-Kristin Fentz, Monika Sporl, Jorg Spangenberg, Heinz Joachim List, et al.
Proteomics Clin. Appl. 2007, 1, 536–544
http://dx.doi.org:/10.1002/prca.200600664

Colorectal cancer is the second leading cause of cancer death, and it develops from benign colorectal adenomas in over 95% of patients. Early detection of these cancer precursors by screening tests and their removal can potentially eradicate more than 95% of colorectal cancers before they develop.
To discover sensitive and specific biomarkers for improvement of pre-clinical diagnosis of colorectal adenoma and cancer, we analysed in two independent studies (n = 87 and n = 83 patients) serum samples from colorectal cancer (stage III), colorectal adenoma and control patients using SELDI-TOF-MS. Extensive statistical analysis was performed to establish homogeneous patient groups based on their clinical data.
Two biomarkers that were each able to distinguish control patients from either colorectal adenoma or colorectal cancer patients (p,0.001) were identified as transthyretin (pre-albumin) and C3adesArg by MS/MS and were further validated by antibody-based assays (radial immunodiffusion, ELISA). A combination of both proteins clearly indicated the presence of colorectal adenoma or carcinoma. Using a cut-off of >0.225 g/L for transthyretin and >1974 ng/mL for C3a-desArg, we found a sensitivity and specificity for colorectal adenoma of 96% and 70%, respectively.

The essential biology of the endoplasmic reticulum stress response for structural and computational biologists

Sadao Wakabayashi, Hiderou Yoshida
CSBJ Mar 2013; 6(7), e201303010 http://dx.doi.org/10.5936/csbj.201303010

The endoplasmic reticulum (ER) stress response is a cytoprotective mechanism that maintains homeostasis of the ER by upregulating the capacity of the ER in accordance with cellular demands. If the ER stress response cannot function correctly, because of reasons such as aging, genetic mutation or environmental stress, unfolded proteins accumulate in the ER and cause ER stress-induced apoptosis, resulting in the onset of folding diseases, including Alzheimer’s disease and diabetes mellitus. Although the mechanism of the ER stress response has been analyzed extensively by biochemists, cell biologists and molecular biologists, many aspects remain to be elucidated. For example, it is unclear how sensor molecules detect ER stress, or how cells choose the two opposite cell fates (survival or apoptosis) during the ER stress response. To resolve these critical issues, structural and computational approaches will be indispensable, although the mechanism of the ER stress response is complicated and difficult to understand holistically at a glance. Here, we provide a concise introduction to the mammalian ER stress response for structural and computational biologists.

Sequence co-evolution gives 3D contacts and structures of protein complexes

Thomas A Hopf, Charlotta P I Schärfe, João P G L M Rodrigues, et al.
eLife 2014;3:e03430 http://dx.doi.org:/10.7554/eLife.03430

Protein–protein interactions are fundamental to many biological processes. Experimental screens have identified tens of thousands of interactions, and structural biology has provided detailed functional insight for select 3D protein complexes. An alternative rich source of information about protein interactions is the evolutionary sequence record. Building on earlier work, we show that analysis of correlated evolutionary sequence changes across proteins identifies residues that are close in space with sufficient accuracy to determine the three-dimensional structure of the protein complexes. We evaluate prediction performance in blinded tests on 76 complexes of known 3D structure, predict protein–protein contacts in 32 complexes of unknown structure, and demonstrate how evolutionary couplings can be used to distinguish between interacting and non-interacting protein pairs in a large complex. With the current growth of sequences, we expect that the method can be generalized to genome-wide elucidation of protein–protein interaction networks and used for interaction predictions at residue resolution.
S-Glutathionylation of Cryptic Cysteines Enhances Titin Elasticity by Blocking Protein Folding

Jorge Alegre-Cebollada, P Kosuri, D Giganti, E Eckels, JA Rivas-Pardo, et al.
Cell, Mar 13, 2014; 156: 1235–1246. http://dx.doi.org/10.1016/j.cell.2014.01.056

The giant elastic protein titin is a determinant factor in how much blood fills the left ventricle during diastole and thus in the etiology of heart disease. Titin has been identified as a target of S-glutathionylation, an end product of the nitric-oxide-signaling cascade that increases cardiac muscle elasticity. However, it is unknown how S-glutathionylation may regulate the elasticity of titin and cardiac tissue.
Here, we show that mechanical unfolding of titin immunoglobulin (Ig) domains exposes buried cysteine residues, which then can be S-glutathionylated. S-glutathionylation of cryptic cysteines greatly decreases the mechanical stability of the parent Ig domain as well as its ability to fold. Both effects favor a more extensible state of titin. Furthermore, we demonstrate that S-glutathionylation of cryptic cysteines in titin mediates mechanochemical modulation of the elasticity of human cardiomyocytes.
We propose that posttranslational modification of cryptic residues is a general mechanism to regulate tissue elasticity.
Encounter complexes and dimensionality reduction in protein–protein association

Dima Kozakov, Keyong Li, David R Hall, Dmitri Beglov, Jiefu Zheng, et al.
eLife 2014;3:e01370 http://dx.doi.org:/10.7554/eLife.01370.001

An outstanding challenge has been to understand the mechanism whereby proteins associate. We report here the results of exhaustively sampling the conformational space in protein–protein association using a physics-based energy function. The agreement between experimental intermolecular paramagnetic relaxation enhancement (PRE) data and the PRE profiles calculated from the docked structures shows that the method captures both specific and non-specific encounter complexes. To explore the energy landscape in the vicinity of the native structure, the nonlinear manifold describing the relative orientation of two solid bodies is projected onto a Euclidean space in which the shape of low energy regions is studied by principal component analysis. Results show that the energy surface is canyon-like, with a smooth funnel within a two dimensional subspace capturing over 75% of the total motion. Thus, proteins tend to associate along preferred pathways, similar to sliding of a protein along DNA in the process of protein-DNA recognition.

Cardiovascular Proteomics: Evolution and Potential

Kent Arrell, Irina Neverova and Jennifer E. Van Eyk
Circ Res. 2001;88:763-773 http://dx.doi.org:/doi:/10.1161/hh0801.090193

The development of proteomics is a timely one for cardiovascular research. Analyses at the organ, subcellular, and molecular levels have revealed dynamic, complex, and subtle intracellular processes associated with heart and vascular disease. The power and flexibility of proteomic analyses, which facilitate protein separation, identification, and characterization, should hasten our understanding of these processes at the protein level. Properly applied, proteomics provides researchers with cellular protein “inventories” at specific moments in time, making it ideal for documenting protein modification due to a particular disease, condition, or treatment. This is accomplished through the establishment of species- and tissue-specific protein databases, providing a foundation for subsequent proteomic studies. Evolution of proteomic techniques has permitted more thorough investigation into molecular mechanisms underlying cardiovascular disease, facilitating identification not only of modified proteins but also of the nature of their modification. Continued development should lead to functional proteomic studies, in which identification of protein modification, in conjunction with functional data from established biochemical and physiological methods, has the ability to further our understanding of the interplay between proteome change and cardiovascular disease.

Advances in Proteomic Technologies and Its Contribution to the Field of Cancer

Mehdi Mesri

Advances in Medicine 2014, Article ID 238045, 25 pages http://dx.doi.org/10.1155/2014/238045

Systematic studies of the cancer genome have generated a wealth of knowledge in recent years. These studies have uncovered a number of new cancer genes not previously known to be causal targets in cancer. Genetic markers can be used to determine predisposition to tumor development, but molecularly targeted treatment strategies are not widely available for most cancers. Precision care plans still must be developed by understanding and implementing basic science research into clinical treatment. Proteomics is continuing to make major strides in the discovery of fundamental biological processes as well as more recent transition into an assay platform capable of measuring hundreds of proteins in any biological system. As such, proteomics can translate basic science discoveries into the clinical practice of precision medicine. The proteomic field has progressed at a fast rate over the past five years in technology, breadth and depth of applications in all areas of the bioscience. Some of the previously experimental technical approaches are considered the gold standard today, and the community is now trying to come to terms with the volume and complexity of the data generated. Here I describe contribution of proteomics in general and biological mass spectrometry in particular to cancer research, as well as related major technical and conceptual developments in the field.

Chemoproteomics reveals Toll-like receptor fatty acylation

Nicholas M Chesarino, Jocelyn C Hach, James L Chen, Balyn W Zaro, et al.
BMC Biology 2014, 12:91 http://www.biomedcentral.com/1741-7007/12/91

Background: Palmitoylation is a 16-carbon lipid post-translational modification that increases protein hydrophobicity. This form of protein fatty acylation is emerging as a critical regulatory modification for multiple aspects of cellular interactions and signaling. Despite recent advances in the development of chemical tools for the rapid identification and visualization of palmitoylated proteins, the palmitoyl proteome has not been fully defined. Here we sought to identify and compare the palmitoylated proteins in murine fibroblasts and dendritic cells.
Results: A total of 563 putative palmitoylation substrates were identified, more than 200 of which have not been previously suggested to be palmitoylated in past proteomic studies. Here we validate the palmitoylation of several new proteins including Toll-like receptors (TLRs) 2, 5 and 10, CD80, CD86, and NEDD4. Palmitoylation of TLR2, which was uniquely identified in dendritic cells, was mapped to a transmembrane domain-proximal cysteine. Inhibition of TLR2 S-palmitoylation pharmacologically or by cysteine mutagenesis led to decreased cell surface expression and a decreased inflammatory response to microbial ligands. Conclusions: This work identifies many fatty acylated proteins involved in fundamental cellular processes as well as cell type-specific functions, highlighting the value of examining the palmitoyl proteomes of multiple cell types. Spalmitoylation of TLR2 is a previously unknown immunoregulatory mechanism that represents an entirely novel avenue for modulation of TLR2 inflammatory activity.

Comparative Proteomics and Network Analysis Identify PKC Epsilon Underlying Long-Chain Fatty Acid Signaling

T Yonezawa, R Kurata, A Tajima, X Cui, H Maruta, H Nakaoka, K Nakajima and H Inokio
J Proteomics Bioinform 2014: 7:11 http://dx.doi.org/10.4172/jpb.1000337

Long-chain fatty acid possesses myriad roles in the biological function of the cells, not only as an energy substrate but also as substrates for cell membrane synthesis and as precursors for intracellular signaling molecules. However, little is known about the biological pathways that are stimulated by long-chain fatty acid. In order to identify the pathway of long-chain fatty acid, we performed 2-dimensional gel electrophoresis in the cells treated with or without oleate, and then analyzed 648 protein spots using PDQuest software and narrowed down 22 significant changing spots by statistical criterion. We also tried to determine these spots by MALDI-QIT-TOF-MS and SWISSPROT database query. We identified 11 proteins and predicted the biological network using available data sets from protein-protein interaction database. This prediction indicated that several protein kinase Cs (PKCs) underlie long chain fatty acid signaling. Indeed, oleate stimulated predicted PKC pathways. In expression array, oleate significantly up-regulated only PKC epsilon, but not other PKCs, in transcriptional levels. Collectively, our proteomics and network analysis implicates that PKC epsilon pathway plays an important role in long-chain fatty acid signaling.
Editorial: The art of proteomics translation

Translational Proteomics 2013; 1: 1–2 http://dx.doi.org/10.1016/j.trprot.2013.03.001

Over the years, the difficulties of transferring fundamental proteomics discoveries to clinical applications have caused a lot of frustration to proteomics researchers and clinicians alike, in both academia and industry. One of the reasons for this barrier is the lack of understanding between basic scientists and physicians: they have been trained using opposing concepts. Whilst the former want to control and understand all variables, the latter need rapid actions on patients, rather than absolute certainties. Both disciplines are difficult to con-dense into a single scientist and therefore interdisciplinary associations need to be fostered. Translational research has often been viewed as a two-way street: bedside to bench, and back to bedside. We should perhaps look at it as a roundabout, with the patient and his disease in the center, surrounded by a constant, iterative inter-play between basic, translational and clinical scientists, from both the public and private sectors. Proteomics research needs more than just a translation road bridge from discoveries to cures. Rather, it requires networks of road junctions to fill all the gaps and to allow cross-fertilization and synergies. Translational research and translational proteomics are more than just interesting concepts and hot keywords, they are supposed to improve the quality of people’s lives. With the launch of Translational Proteomics, we want to help the scientific and medical communities overcome the challenges on the long path from discovery to patient care. By focusing on connecting basic proteomics research to its ultimate clinical applications, the Journal will provide a space for publications detailing proteomics experiments, from early discovery to validation and the bedside.

Structural Basis of Diverse Membrane Target Recognitions by Ankyrins

C Wang, Z Wei, K Chen, F Ye, C Yu, V Bennett, and M Zhang
eLife 2014; http:dx.doi.org:/10.7554/eLife.04353

Ankyrin adaptors together with their spectrin partners coordinate diverse ion channels and cell adhesion molecules within plasma membrane domains and thereby promote physiological activities including fast signaling in the heart and nervous system. Ankyrins specifically bind to numerous membrane targets through their 24 ankyrin repeats (ANK repeats), although the mechanism for the facile and independent evolution of these interactions has not been resolved. Here we report the structures of ANK repeats in complex with an inhibitory segment from the C-terminal regulatory domain and with a sodium channel Nav1.2 peptide, respectively, showing that the extended, extremely conserved inner groove spanning the entire ANK repeat solenoid contains multiple target binding sites capable of accommodating target protein with very diverse sequences via combinatorial usage of these sites. These structures establish a framework for understanding the evolution of ankyrins’ membrane targets, with implications for other proteins containing extended ANK repeat domains.

Fusion of Protein Aggregates Facilitates Asymmetric Damage Segregation

Miguel Coelho, Steven J. Lade, Simon Alberti, Thilo Gross, Iva M. Tolic
PLOS Biology June 2014; 12(6):e1001886
http://dx.doi.org:/10.1371/journal.pbio.1001886

Asymmetric segregation of damaged proteins at cell division generates a cell that retains damage and a clean cell that supports population survival. In cells that divide asymmetrically, such as Saccharomyces cerevisiae, segregation of damaged proteins is achieved by retention and active transport. We have previously shown that in the symmetrically dividing Schizosaccharomyces pombe there is a transition between symmetric and asymmetric segregation of damaged proteins. Yet how this transition and generation of damage-free cells are achieved remained unknown. Here, by combining in vivo imaging of Hsp104-associated aggregates, a form of damage, with mathematical modeling, we find that fusion of protein aggregates facilitates asymmetric segregation. Our model predicts that, after stress, the increased number of aggregates fuse into a single large unit, which is inherited asymmetrically by one daughter cell, whereas the other one is born clean. We experimentally confirmed that fusion increases segregation asymmetry, for a range of stresses, and identified Hsp16 as a fusion factor. Our work shows that fusion of protein aggregates promotes the formation of damage-free cells. Fusion of cellular factors may represent a general mechanism for their asymmetric segregation at division.

Symmetric exchange of multi-protein building blocks between stationary focal adhesions and the cytosol

Jan-Erik Hoffmann, Y Fermin, R LO Stricker, K Ickstadt, E Zamir
eLife 2014;3:e02257. http://dx.doi.org:/10.7554/eLife.02257.001

How can the integrin adhesome get self-assembled locally, rapidly, and correctly as diverse cell-matrix adhesion sites? Here, we investigate this question by exploring the cytosolic state of integrin-adhesome components and their dynamic exchange between adhesion sites and cytosol. Using fluorescence cross-correlation spectroscopy (FCCS) and fluorescence recovery after photo-bleaching (FRAP) we found that the integrin adhesome is extensively pre-assembled already in the cytosol as multi-protein building blocks for adhesion sites. Stationary focal adhesions release symmetrically the same types of protein complexes that they recruit, thereby keeping the cytosolic pool of building blocks spatiotemporally uniform. We conclude a model in which multi-protein building blocks enable rapid and modular self-assembly of adhesion sites and symmetric exchange of these building blocks preserves their specifications and thus the assembly logic of the system.

Redox signaling via the molecular chaperone BiP protects cells against endoplasmic reticulum-derived oxidative stress

Jie Wang, Kristeen A Pareja, Chris A Kaiser, Carolyn S Sevier
eLife 2014;3:e03496. http://dx.doi.org:/10.7554/eLife.03496

Oxidative protein folding in the endoplasmic reticulum (ER) has emerged as a potentially significant source of cellular reactive oxygen species (ROS). Recent studies suggest that levels of ROS generated as a byproduct of oxidative folding rival those produced by mitochondrial respiration. Mechanisms that protect cells against oxidant accumulation within the ER have begun to be elucidated yet many questions still remain regarding how cells prevent oxidant-induced damage from ER folding events. Here we report a new role for a central well-characterized player in ER homeostasis as a direct sensor of ER redox imbalance. Specifically we show that a conserved cysteine in the lumenal chaperone BiP is susceptible to oxidation by peroxide, and we demonstrate that oxidation of this conserved cysteine disrupts BiP’s ATPase cycle. We propose that alteration of BiP activity upon oxidation helps cells cope with disruption to oxidative folding within the ER during oxidative stress.

Current perspectives on cadherin-cytoskeleton interactions and dynamics

Xuan Liang, Guillermo A Gomez, Alpha S Yap
Cell Health and Cytoskeleton 2015:7 11–24
http://dx.doi.org/10.2147/CHC.S76107

Cells are linked together dynamically by adhesion molecules, such as the classical cadherins. E-cadherin, which mediates epithelial cell–cell interactions, plays fundamental roles in tissue organization and is often perturbed in diseases such as cancer. It has long been recognized that the biology of E-cadherin arises from cooperation between adhesion and the actin cytoskeleton. A major feature is the generation of contractile forces at junctions, yielding patterns of tension that contribute to tissue integrity and patterning. Here we discuss recent developments in understanding how cadherin junctions integrate signaling and cytoskeletal dynamics to sense and generate force.

N-glycosylation status of E-cadherin controls cytoskeletal dynamics through the organization of distinct β-catenin- and γ-catenin-containing AJs

Basem T Jamal, M Nita-Lazar, Z Gao, B Amin, J Walker, MA Kukuruzinska
Cell Health and Cytoskeleton 2009:1 67–80

N-glycosylation of E-cadherin has been shown to inhibit cell–cell adhesion. Specifically, our recent studies have provided evidence that the reduction of E-cadherin N-glycosylation promoted the recruitment of stabilizing components, vinculin and serine/threonine protein phosphatase 2A (PP2A), to adherens junctions (AJs) and enhanced the association of AJs with the actin cytoskeleton. Here, we examined the details of how N-glycosylation of E-cadherin affected the molecular organization of AJs and their cytoskeletal interactions. Using the hypoglycosylated E-cadherin variant, V13, we show that V13/β-catenin complexes preferentially interacted with PP2A and with the microtubule motor protein dynein. This correlated with dephosphorylation of the microtubule-associated protein tau, suggesting that increased association of PP2A with V13-containing AJs promoted their tethering to microtubules. On the other hand, V13/γ-catenin complexes associated more with vinculin, suggesting that they mediated the interaction of AJs with the actin cytoskeleton. N-glycosylation driven changes in the molecular organization of AJs were physiologically significant because transfection of V13 into A253 cancer cells, lacking both mature AJs and tight junctions (TJs), promoted the formation of stable AJs and enhanced the function of TJs to a greater extent than wild-type E-cadherin. These studies provide the first mechanistic insights into how N-glycosylation of E-cadherin drives changes in AJ composition through the assembly of distinct β-catenin- and γ-catenin-containing scaffolds that impact the interaction with different cytoskeletal components.

Mapping the dynamics of force transduction at cell-cell 4 junctions of epithelial clusters

Mei Rosa Ng, Achim Besser, Joan S. Brugge, Gaudenz Danuser
eLife 2014;10.7554/eLife.03282
http://dx.doi.org/10.7554/eLife.03282

Force transduction at cell-cell adhesions regulates tissue development, maintenance and adaptation. We developed computational and experimental approaches to quantify, with both subcellular and multi-cellular resolution, the dynamics of force transmission in cell clusters. Applying this technology to spontaneously-forming adherent epithelial cell clusters, we found that basal force fluctuations were coupled to E-cadherin localization at the level of individual cell-cell junctions. At the multi-cellular scale, cell-cell force exchange depended on the cell position within a cluster, and was adaptive to reconfigurations due to cell divisions or positional rearrangements. Importantly, force transmission through a cell required coordinated modulation of cell-matrix adhesion and actomyosin contractility in the cell and its neighbors. These data provide insights into mechanisms that could control mechanical stress homeostasis in dynamic epithelial tissues, and highlight our methods as a resource for the study of mechanotransduction in cell-cell adhesions.

G-protein-coupled receptor signaling and polarized actin dynamics drive cell-in-cell invasion

Vladimir Purvanov, Manuel Holst, Jameel Khan, Christian Baarlink, Robert Grosse
eLife 2014;3:e02786. http://dx.doi.org:/10.7554/eLife.02786

Homotypic or entotic cell-in-cell invasion is an integrin-independent process observed in carcinoma cells exposed during conditions of low adhesion such as in exudates of malignant disease. Although active cell-in-cell invasion depends on RhoA and actin, the precise mechanism as well as the underlying actin structures and assembly factors driving the process are unknown. Furthermore, whether specific cell surface receptors trigger entotic invasion in a signal-dependent fashion has not been investigated. In this study, we identify the G-protein-coupled LPA receptor 2 (LPAR2) as a signal transducer specifically required for the actively invading cell during entosis. We find that G12/13 and PDZ-RhoGEF are required for entotic invasion, which is driven by blebbing and a uropod-like actin structure at the rear of the invading cell. Finally, we provide evidence for an involvement of the RhoA-regulated formin Dia1 for entosis downstream of LPAR2. Thus, we delineate a signaling process that regulates actin dynamics during cell-in-cell invasion.

Cytoskeletal Basis of Ion Channel Function in Cardiac Muscle

Matteo Vatta, and Georgine Faulkner
Future Cardiol. 2006 Jul 1; 2(4): 467–476. http://dx.doi.org:/10.2217/14796678.2.4.467

The heart is a force-generating organ that responds to self-generated electrical stimuli from specialized cardiomyocytes. This function is modulated by sympathetic and parasympathetic activity.

In order to contract and accommodate the repetitive morphological changes induced by the cardiac cycle, cardiomyocytes depend on their highly evolved and specialized cytoskeletal apparatus. Defects in components of the cytoskeleton, in the long term, affect the ability of the cell to compensate at both functional and structural levels. In addition to the structural remodeling, the myocardium becomes increasingly susceptible to altered electrical activity leading to arrhythmogenesis. The development of arrhythmias secondary to structural remodeling defects has been noted, although the detailed molecular mechanisms are still elusive. Here I will review the current knowledge of the molecular and functional relationships between the cytoskeleton and ion channels and, I will discuss the future impact of new data on molecular cardiology research and clinical practice.

Structure and transport mechanism of the sodium/proton 2 antiporter MjNhaP1

Cristina Paulino, D Wöhlert , E Kapotova, Ö Yildiz & W Kühlbrandt
eLife 2014; http://dx.doi.org/10.7554/eLife.03583

Sodium/proton antiporters are essential for sodium and pH homeostasis and play a major role in human health and disease. We determined the structures of the archaeal sodium/proton antiporter MjNhaP1 in two complementary states. The inward-open state was obtained by x-ray crystallography in the presence of sodium at pH8, where the transporter is highly active. The outward-open state was obtained by electron crystallography without sodium at pH4, where MjNhaP1 is inactive. Comparison of both structures reveals a 7° tilt of the 6-helix bundle. Na+ uptake measurements indicate non-cooperative transport with an activity maximum at pH7.5. We conclude that binding of a Na+ ion from the outside induces helix movements that close the extracellular cavity, open the cytoplasmic funnel, and result in a ~5 Å vertical relocation of the ion binding site to release the substrate ion into the cytoplasm.

Integrated control of transporter endocytosis and recycling by the arrestin-related protein Rod1 and the ubiquitin ligase Rsp5

Michel Becuwe, Sébastien Léon
eLife 2014; http://dx.doi.org/10.7554/eLife.03307

After endocytosis, membrane proteins can recycle to the cell membrane or be degraded in lysosomes. Cargo ubiquitylation favors their lysosomal targeting and can be regulated by external signals, but the mechanism is ill-defined. Here, we studied the post-endocytic trafficking of Jen1, a yeast monocarboxylate transporter, using microfluidics-assisted live cell imaging. We show that the ubiquitin ligase Rsp5 and the glucose-regulated arrestin related (ART) protein Rod1, involved in the glucose-induced internalization of Jen1, are also required for the post-endocytic sorting of Jen1 to the yeast lysosome. This new step takes place at the trans-Golgi network (TGN), where Rod1 localizes dynamically upon triggering endocytosis. Indeed, transporter trafficking to the TGN after internalization is required for their degradation. Glucose removal promotes Rod1 relocalization to the cytosol and Jen1 deubiquitylation, allowing transporter recycling when the signal is only transient. Therefore, nutrient availability regulates transporter fate through the localization of the ART/Rsp5 ubiquitylation complex at the TGN.

McKenney, W Huynh, ME. Tanenbaum, G Bhabha, and RD. Vale
Science Express 19 June 2014 /10.1126/science.1254198
http://www.sciencemag.org/content/early/recent/10.1126/science.1254198

Cytoplasmic dynein is a molecular motor that transports a large variety of cargoes (e.g., organelles, mRNAs, and viruses) along microtubules over long intracellular distances. The dynactin protein complex is important for dynein activity in vivo, but its precise role has been unclear. Here, we found that purified mammalian dynein did not move processively on microtubules in vitro. However, when dynein formed a complex with dynactin and one of four different cargo-specific adapter proteins, the motor became ultra-processive, moving for distances similar to those of native cargoes in living cells. Thus, we propose that dynein is largely inactive in the cytoplasm and that a variety of adapter proteins activate processive motility by linking dynactin to dynein only when the motor is bound to its proper cargo.

Removal of surface charge–charge interactions from ubiquitin leaves the protein folded and very stable

Vakhtang V. Loladze And George I. Makhatadze
Protein Science (2002), 11:174–177
http://www.proteinscience.org/cgi/doi/10.1101/ps.29902.

The contribution of solvent-exposed charged residues to protein stability was evaluated using ubiquitin as a model protein. We combined site-directed mutagenesis and specific chemical modifications to first replace all Arg residues with Lys, followed by carbomylation of Lys- amino groups. Under the conditions in which all carboxylic groups are protonated (at pH 2), the chemically modified protein is folded and very stable (dG= 18 kJ/mol). These results indicate that surface charge–charge interactions are not an essential fundamental force for protein folding and stability.

Phase Transitions of Multivalent Proteins Can Promote Clustering of Membrane Receptors

Sudeep Banjade and Michael K. Rosen
eLife 2014; http://dx.doi.org/10.7554/eLife.04123

Clustering of proteins into micrometer-sized structures at membranes is observed in many signaling pathways. Most models of clustering are specific to particular systems, and relationships between physical properties of the clusters and their molecular components are not well understood. We report biochemical reconstitution on supported lipid bilayers of protein clusters containing the adhesion receptor Nephrin, and its cytoplasmic partners, Nck and N-WASP. With Nephrin attached to the bilayer, multivalent interactions enable these proteins to polymerize on the membrane surface and undergo two-dimensional phase separation, producing micrometer-sized clusters. Dynamics and thermodynamics of the clusters are modulated by the valencies and affinities of the interacting species. In the presence of the Arp2/3 complex, the clusters assemble actin filaments, suggesting that clustering of regulatory factors could promote local actin assembly at membranes. Interactions between multivalent proteins could be a general mechanism for cytoplasmic adaptor proteins to organize membrane receptors into micrometer-scale signaling zones.

The quantitative architecture of centromeric chromatin

Dani L Bodor, João F Mata, Mikhail Sergeev, Ana Filipa David, et al.
eLife 2014;3:e02137. http://dx.doi.org:/10.7554/eLife.02137

The centromere, responsible for chromosome segregation during mitosis, is epigenetically defined by CENP-A containing chromatin. The amount of centromeric CENP-A has direct implications for both the architecture and epigenetic inheritance of centromeres. Using complementary strategies, we determined that typical human centromeres contain ∼400 molecules of CENP-A, which is controlled by a mass-action mechanism. This number, despite representing only ∼4% of all centromeric nucleosomes, forms a ∼50-fold enrichment to the overall genome. In addition, although pre-assembled CENP-A is randomly segregated during cell division, this amount of CENP-A is sufficient to prevent stochastic loss of centromere function and identity. Finally, we produced a statistical map of CENP-A occupancy at a human neocentromere and identified nucleosome positions that feature CENP-A in a majority of cells. In summary, we present a quantitative view of the centromere that provides a mechanistic framework for both robust epigenetic inheritance of centromeres and the paucity of neocentromere formation.

Synaptic proteins promote calcium-triggered fast transition from point contact to full fusion

Jiajie Diao, Patricia Grob, Daniel J Cipriano, Minjoung Kyoung
eLife 2012;1:e00109. http://dx.doi.org:/10.7554/eLife.00109

The molecular underpinnings of synaptic vesicle fusion for fast neurotransmitter release are still unclear. Here, we used a single vesicle–vesicle system with reconstituted SNARE and synaptotagmin-1 proteoliposomes to decipher the temporal sequence of membrane states upon Ca2+-injection at 250–500 μM on a 100-ms timescale. Furthermore, detailed membrane morphologies were imaged with cryo-electron microscopy before and after Ca2+-injection. We discovered a heterogeneous network of immediate and delayed fusion pathways. Remarkably, all instances of Ca2+-triggered immediate fusion started from a membrane–membrane point-contact and proceeded to complete fusion without discernible hemifusion intermediates. In contrast, pathways that involved a stable hemifusion diaphragm only resulted in fusion after many seconds, if at all. When complexin was included, the Ca2+-triggered fusion network shifted towards the immediate pathway, effectively synchronizing fusion, especially at lower Ca2+-concentration. Synaptic proteins may have evolved to select this immediate pathway out of a heterogeneous network of possible membrane fusion pathways.

Cytoskeleton, cytoskeletal interactions, and vascular endothelial function

Jingli Wang, Michael E Widlansky
Cell Health and Cytoskeleton 2012:4 119–127
http://dx.doi.org/10.2147/CHC.S21823

Far from being inert, the vascular endothelium is a critical regulator of vascular function. While the endothelium participates in autocrine, paracrine, and endocrine signaling, it also transduces mechanical signals from the cell surface involving key cell structural elements. In this review, we discuss the structure of the vascular endothelium and its relationship to traditional cardiovascular risk factors and clinical cardiovascular events. Further, we review the emerging evidence that cell structural elements, including the glycocalyx, intercellular junctions, and cytoskeleton elements, help the endothelium to communicate with its environment to regulate vascular function, including vessel permeability and signal transduction via nitric oxide bioavailability. Further work is necessary to better delineate the regulatory relationships between known key regulators of vascular function and endothelial cell structural elements.

Cellular prion protein is required for neuritogenesis: fine-tuning of multiple signaling pathways involved in focal adhesions and actin cytoskeleton dynamics

Aurélie Alleaume-Butaux, C Dakowski, M Pietri, S Mouillet-Richard, et al.
Cell Health and Cytoskeleton 2013:5 1–12
http://dx.doi.org/10.2147/CHC.S28081

Neuritogenesis is a dynamic phenomenon associated with neuronal differentiation that allows a rather spherical neuronal stem cell to develop dendrites and axon, a prerequisite for the integration and transmission of signals. The acquisition of neuronal polarity occurs in three steps: (1) neurite sprouting, which consists of the formation of buds emerging from the postmitotic neuronal soma; (2) neurite outgrowth, which represents the conversion of buds into neurites, their elongation and evolution into axon or dendrites; and (3) the stability and plasticity of neuronal polarity. In neuronal stem cells, remodeling and activation of focal adhesions (FAs) associated with deep modifications of the actin cytoskeleton is a prerequisite for neurite sprouting and subsequent neurite outgrowth. A multiple set of growth factors and interactors located in the extracellular matrix and the plasma membrane orchestrate neuritogenesis by acting on intracellular signaling effectors, notably small G proteins such as RhoA, Rac, and Cdc42, which are involved in actin turnover and the dynamics of FAs. The cellular prion protein (PrPC), a glycosylphosphatidylinositol (GPI)-anchored membrane protein mainly known for its role in a group of fatal neurodegenerative diseases, has emerged as a central player in neuritogenesis. Here, we review the contribution of PrPC to neuronal polarization and detail the current knowledge on the signaling pathways fine-tuned by PrPC to promote neurite sprouting, outgrowth, and maintenance. We emphasize that PrPC-dependent neurite sprouting is a process in which PrPC governs the dynamics of FAs and the actin cytoskeleton via β1 integrin signaling. The presence of PrPC is necessary to render neuronal stem cells competent to respond to neuronal inducers and to develop neurites. In differentiating neurons, PrPC exerts a facilitator role towards neurite elongation. This function relies on the interaction of PrPC with a set of diverse partners such as elements of the extracellular matrix, plasma membrane receptors, adhesion molecules, and soluble factors that control actin cytoskeleton turnover through Rho-GTPase signaling. Once neurons have reached their terminal stage of differentiation and acquired their polarized morphology, PrPC also takes part in the maintenance of neurites. By acting on tissue nonspecific alkaline phosphatase, or matrix metalloproteinase type 9, PrPC stabilizes interactions between neurites and the extracellular matrix.

Broader implications: biological and clinical significance of microtubule acetylation

Sharon M Rymut, Thomas J Kelley
Cell Health and Cytoskeleton 2015:7 71–82
http://dx.doi.org/10.2147/CHC.S77040

Microtubule acetylation is a key posttranslational modification that enhances organelle transport, drives cell signaling, and regulates cell cycle regulation. The optimal level of microtubule acetylation is regulated by the acetyltransferase alpha-tubulin-N-acetyltransferase 1and two deacetylases, histone deacetylase 6 and sirtuin-2. Alterations in microtubule acetylation levels have been associated with the pathophysiology of a number of diseases, including various forms of neurodegenerative conditions, cancer, and even cystic fibrosis. In this review, we will highlight the biological and clinical significance of microtubule acetylation and the potential of targeting this pathway for therapeutics.

Inositol-1,4,5-trisphosphate 1 (IP3)-mediated STIM1 oligomerization requires intact mitochondrial Ca2+ uptake

Deak, S. Blass, M. J. Khan, L. N. Groschner, M. Waldeck-Weiermair, et al.
Journal of Cell Science 2014 advanced print

Mitochondria contribute to cell signaling by controlling store-operated Ca2+ entry (SOCE). SOCE is activated by Ca2+ release from the endoplasmic reticulum (ER), whereupon the stromal interacting molecule 1 (STIM1) forms oligomers, redistributes to ER-plasma membrane junctions, and opens plasma membrane Ca2+ channels. Mechanisms by which mitochondria interfere with the complex process of SOCE are insufficiently clarified. In this study we used a shRNA approach to investigate the direct involvement of mitochondrial Ca2+ buffering in SOCE. We demonstrate that knock-down of two proteins that are essential for mitochondrial Ca2+ uptake, either the mitochondrial calcium uniporter (MCU) or uncoupling protein 2 (UCP2), results in decelerated STIM1 oligomerization and impaired SOCE following cell stimulation with an inositol-1,4,5-trisphosphate (IP3)-generating agonist. Upon artificially augmented cytosolic Ca2+-buffering or ER Ca2+ depletion by sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitors, STIM1 oligomerization did not rely on intact mitochondrial Ca2+ uptake. However, MCU-dependent mitochondrial sequestration of Ca2+ entering through the SOCE pathway was essential to prevent slow deactivation of SOCE. Our findings show a stimulus specific contribution of mitochondrial Ca2+ uptake to the SOCE machinery likely by shaping cytosolic Ca2+ micro-domains.

Role of forkhead box protein A3 in age-associated metabolic decline

Xinran Ma, Lingyan Xu, Oksana Gavrilov, and Elisabetta Mueller
PNAS | September 30, 2014 | vol. 111 | no. 39 | 14289–14294
www.pnas.org/cgi/doi/10.1073/pnas.1407640111

Aging is associated with increased adiposity and diminished thermogenesis, but the critical transcription factors influencing these metabolic changes late in life are poorly understood. We recently demonstrated that the winged helix factor forkhead box protein A3 (Foxa3) regulates the expansion of visceral adipose tissue in high-fat diet regimens; however, whether Foxa3 also contributes to the increase in adiposity and the decrease in brown fat activity observed during the normal aging process is currently unknown.
Here we report that during aging, levels of Foxa3 are significantlyand selectively up-regulated in brown and inguinal white fat depots, and that midage Foxa3-null mice have increased white fat browning and thermogenic capacity, decreased adipose tissue expansion, improved insulin sensitivity, and increased longevity. Foxa3 gain-of-function and loss-of-function studies in inguinal adipose depots demonstrated a cell-autonomous function for Foxa3 in white fat tissue browning. Furthermore, our analysis revealed that the mechanisms of Foxa3 modulation of brown fat gene programs involve the suppression of peroxisome proliferator activated receptor γ coactivtor 1 α (PGC1α) levels through interference with cAMP responsive element binding protein 1-mediated transcriptional regulation of the PGC1α promoter. Overall, our data demonstrate a role for Foxa3 in energy expenditure and in age-associated metabolic disorders.

Prediction of enzyme function by combining sequence similarity and protein interactions

Jordi Espadaler, Narayanan Eswa, Enrique Querol, Francesc X Avilés, et al.
BMC Bioinformatics 2008, 9:249 http://dx.doi.org:/10.1186/1471-2105-9-249

Background: A number of studies have used protein interaction data alone for protein function prediction. Here, we introduce a computational approach for annotation of enzymes, based on the observation that similar protein sequences are more likely to perform the same function if they share similar interacting partners.
Results: The method has been tested against the PSI-BLAST program using a set of 3,890 protein sequences from which interaction data was available. For protein sequences that align with at least 40% sequence identity to a known enzyme, the specificity of our method in predicting the first three EC digits increased from 80% to 90% at 80% coverage when compared to PSI-BLAST.
Conclusion: Our method can also be used in proteins for which homologous sequences with known interacting partners can be detected. Thus, our method could increase 10% the specificity of genome-wide enzyme predictions based on sequence matching by PSI-BLAST alone.

Plasma Transthyretin Indicates the Direction of both Nitrogen Balance and Retinoid Status in Health and Disease

Ingenbleek Yves and Bienvenu Jacques
The Open Clinical Chemistry Journal, 2008, 1, 1-12

Whatever the nutritional status and the disease condition, the actual transthyretin (TTR) plasma level is determined by opposing influences between anabolic and catabolic alterations. Rising TTR values indicate that synthetic processes prevail over tissue breakdown with a nitrogen balance (NB) turning positive as a result of efficient nutritional support and / or anti-inflammatory therapy. Declining TTR values point to the failure of sustaining NB as an effect of maladjusted dietetic management and / or further worsening of the morbid condition. Serial measurement of TTR thus appears as a dynamic index defining the direction of NB in acute and chronic disorders, serving as a guide to alert the physician on the validity of his therapeutic strategy. The level of TTR production by the liver also works as a limiting factor for the cellular bioavailability of retinol and retinoid derivatives which play major roles in the brain ageing process. Optimal protein nutritional status, as assessed by TTR values within the normal range, prevents the occurrence of vascular and cerebral damages while maintaining the retinoid-mediated memory, cognitive and behavioral activities of elderly persons.

Prof. Dr. Volker Haucke
Institut für Chemie-Biochemie
Takustrasse 6
http://userpage.chemie.fu-berlin.de/biochemie/aghaucke/teaching.html

Eukaryotic cells contain three major types of cytoskeletal filaments

major types of cytoskeletal filaments

Intermediate Filaments support the nuclear membrane and connect cells at cell junctions

microtubules (MTs; green) radiate from MTOCs (yellow) towards the cell periphery

Actin polymerization in vitro reveals a critical dependence of filament assembly on G-actin concentration via a 3-step nucleation mechanism

Binding-proteins and receptors

Motor, visual and emotional deficits in mice after closed-head mild traumatic brain injury are alleviated by the novel CB2 inverse agonist SMM-189
Reiner, A., Heldt, S.A., Presley, C.S., (…), Gurley, S.N., Moore, B.M.
2015 International Journal of Molecular Sciences 16 (1), pp. 758-787

We have developed a focal blast model of closed-head mild traumatic brain injury (TBI) in mice. As true for individuals that have experienced mild TBI, mice subjected to 50-60 psi blast show motor, visual and emotional deficits, diffuse axonal injury and microglial activation, but no overt neuron
loss. Because microglial activation can worsen brain damage after a concussive event and because microglia can be
modulated by their cannabinoid type 2 receptors (CB2), we evaluated the effectiveness of the novel CB2 receptor inverse agonist SMM-189 in altering microglial activation and mitigating deficits after mild TBI. In vitro analysis indicated that SMM-189 converted human microglia from the pro-inflammatory M1 phenotype to the pro-healing M2 phenotype. Studies in mice showed that daily administration of SMM-189 for two weeks beginning shortly after blast greatly reduced the motor, visual, and emotional deficits otherwise evident after 50-60 psi blasts, and prevented brain injury that may contribute to these deficits. Our results suggest that treatment with the CB2 inverse agonist SMM-189 after a mild TBI event can reduce its adverse consequences by beneficially modulating microglial activation. These
findings recommend further evaluation of CB2 inverse agonists as a novel therapeutic approach for treating mild TBI.

The novel small leucine-rich protein chondroadherin-like (CHADL) is expressed in cartilage and modulates chondrocyte differentiation
Tillgren, V., Ho, J.C.S., Önnerfjord, P., Kalamajski, S.
2015 Journal of Biological Chemistry 290 (2), pp. 918-925

The constitution and biophysical properties of extracellular matrices can dramatically influence cellular phenotype during development, homeostasis, or pathogenesis. These effects can be signaled through a differentially regulated assembly of collagen fibrils, orchestrated by a family of collagen-associated small leucine-rich proteins (SLRPs). In this report, we describe the tissue-specific expression and function of a previously uncharacterized SLRP, chondroadherin-like (CHADL). We developed antibodies against CHADL and, by immunohistochemistry, detected CHADL expression mainly in skeletal tissues, particularly in fetal cartilage and in the pericellular space of adult chondrocytes. In situ hybridizations and immunoblots on tissue lysates confirmed this tissue-specific expression pattern. Recombinant CHADL bound collagen in cell culture and inhibited in vitro collagen fibrillogenesis. After Chadl shRNA knockdown, chondrogenic ATDC5 cells increased their differentiation, indicated by increased transcript levels of Sox9, Ihh, Col2a1, and Col10a1. The knockdown increased collagen II and aggrecan deposition in the cell layers.

Microarray analysis of the knockdown samples suggested collagen receptor-related changes, although other upstream effects could not be excluded. Together, our data indicate that the novel SLRP CHADL is expressed in cartilaginous tissues, influences collagen fibrillogenesis, and modulates chondrocyte differentiation. CHADL appears to have a negative regulatory role, possibly ensuring the formation of a stable extracellular matrix.

P53 protein-mediated Up-regulation of MAP kinase phosphatase 3 (MKP-3) contributes to the establishment of the cellular senescent phenotype through dephosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2)
Zhang, H., Chi, Y., Gao, K., Zhang, X., Yao, J.
2015 Source of the DocumentJournal of Biological Chemistry 290 (2), pp. 1129-1140

Growth arrest is one of the essential features of cellular senescence. At present, the precise mechanisms responsible for the establishment of the senescence-associated arrested phenotype are still incompletely understood. Given that ERK1/2 is one of the major kinases controlling cell growth and proliferation, we examined the possible implication of ERK1/2. Exposure of normal rat epithelial cells to etoposide caused cellular senescence, as manifested by enlarged cell size, a flattened cell body, reduced cell proliferation, enhanced ?-galactosidase activity, and elevated p53 and p21. Senescent cells displayed a blunted response to growth factor-induced cell proliferation, which was preceded by impaired ERK1/2 activation. Further analysis revealed that senescent cells expressed a significantly higher level of mitogenactivated protein phosphatase 3 (MKP-3, a cytosolic ERK1/2-targeted phosphatase), which was suppressed by blocking the transcriptional activity of the tumor suppressor p53 with pifithrin-?. Inhibition of MKP-3 activity with a specific inhibitor or siRNA enhanced basal ERK1/2 phosphorylation and promoted cell proliferation. Apart from its role in growth arrest, impairment of ERK1/2 also contributed to the resistance of senescent cells to oxidant-elicited cell injury. These results therefore indicate that p53-mediated up-regulation of MKP-3 contributes to the establishment of the senescent cellular phenotype through dephosphorylating ERK1/2. Impairment of ERK1/2 activation could be an important mechanism by which p53 controls cellular senescence.

Dynamics and interaction of Interleukin-4 receptor subunits in living cells
Gandhi, H., Worch, R., Kurgonaite, K., (…), Bökel, C., Weidemann, T.
2015 Biophysical Journal 107 (11), pp. 2515-2527

It has long been established that dimerization of Interleukin-4 receptor (IL-4R) subunits is a pivotal step for JAK/STAT signal transduction. However, ligand-induced complex formation at the surface of living cells has been challenging to observe. Here we report an experimental assay employing trisNTA dyes for orthogonal, external labeling of eGFP-tagged receptor constructs that allows the quantification of receptor heterodimerization by dual-color fluorescence cross-correlation spectroscopy. Fluorescence cross-correlation spectroscopy analysis at the plasma membrane shows that IL-4R subunit dimerization is indeed a strictly ligand-induced process.

Under conditions of saturating cytokine occupancy, we determined intramembrane dissociation constants (Kd,2D) of 180 and 480 receptors per ?m2 for the type-2 complexes IL-4:IL-4R?/IL-13R?1 and IL-13:IL-13R?1/IL-4R?, respectively. For the lower affinity type-1 complex IL-4:IL-4R?/IL-2R?, we estimated a Kd,2D of ?1000 receptors per ?m2. The receptor densities required for effective dimerization thus exceed the typical, average expression levels by several orders of magnitude. In addition, we find that all three receptor subunits accumulate rapidly within a subpopulation of early sorting and recycling endosomes stably anchored just beneath the plasma membrane (cortical endosomes, CEs). The receptors, as well as labeled IL-4 and trisNTA ligands are specifically trafficked into CEs by a constitutive internalization mechanism. This may compensate for the inherent weak affinities that govern ligand-induced receptor dimerization at the plasma membrane. Consistently, activated receptors are also concentrated at the CEs. Our observations thus suggest that receptor trafficking may play an important role for the regulation of IL-4R-mediated JAK/STAT signaling.

Role of mitochondria in nonalcoholic fatty liver disease
Nassir, F., Ibdah, J.A.
2015 International Journal of Molecular Sciences 15 (5), pp. 8713-8742

Nonalcoholic fatty liver disease (NAFLD) affects about 30% of the general population in the United States and includes a spectrum of disease that includes simple steatosis, non-alcoholic steatohepatitis (NASH), fibrosis and cirrhosis. Significant insight has been gained into our understanding of the pathogenesis of NALFD; however the key metabolic aberrations underlying lipid accumulation in hepatocytes and the progression of NAFLD remain to be elucidated. Accumulating and emerging evidence indicate that hepatic mitochondria play a critical role in the development and pathogenesis of steatosis and NAFLD. Here, we review studies that document a link between the pathogenesis of NAFLD and hepatic mitochondrial dysfunction with particular focus on new insights into the role of impaired fatty acid oxidation, the transcription factor peroxisome proliferator-activated receptor-? coactivator-1? (PGC-1?), and sirtuins in development and progression of NAFLD.

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