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Lesson 5 Cell Signaling And Motility: Cytoskeleton & Actin: Curations and Articles of reference as supplemental information: #TUBiol3373

Curator: Stephen J. Williams, Ph.D.

Cell motility or migration is an essential cellular process for a variety of biological events. In embryonic development, cells migrate to appropriate locations for the morphogenesis of tissues and organs. Cells need to migrate to heal the wound in repairing damaged tissue. Vascular endothelial cells (ECs) migrate to form new capillaries during angiogenesis. White blood cells migrate to the sites of inflammation to kill bacteria. Cancer cell metastasis involves their migration through the blood vessel wall to invade surrounding tissues.

Please Click on the Following Powerpoint Presentation for Lesson 4 on the Cytoskeleton, Actin, and Filaments

CLICK ON LINK BELOW

cell signaling 5 lesson

This post will be updated with further information when we get into Lesson 6 and complete our discussion on the Cytoskeleton

Please see the following articles on Actin and the Cytoskeleton in Cellular Signaling

Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility

This article, constitutes a broad, but not complete review of the emerging discoveries of the critical role of calcium signaling on cell motility and, by extension, embryonic development, cancer metastasis, changes in vascular compliance at the junction between the endothelium and the underlying interstitial layer.  The effect of calcium signaling on the heart in arrhtmogenesis and heart failure will be a third in this series, while the binding of calcium to troponin C in the synchronous contraction of the myocardium had been discussed by Dr. Lev-Ari in Part I.

Universal MOTIFs essential to skeletal muscle, smooth muscle, cardiac syncytial muscle, endothelium, neovascularization, atherosclerosis and hypertension, cell division, embryogenesis, and cancer metastasis. The discussion will be presented in several parts:
1.  Biochemical and signaling cascades in cell motility
2.  Extracellular matrix and cell-ECM adhesions
3.  Actin dynamics in cell-cell adhesion
4.  Effect of intracellular Ca++ action on cell motility
5.  Regulation of the cytoskeleton
6.  Role of thymosin in actin-sequestration
7.  T-lymphocyte signaling and the actin cytoskeleton

 

Identification of Biomarkers that are Related to the Actin Cytoskeleton

In this article the Dr. Larry Bernstein covers two types of biomarker on the function of actin in cytoskeleton mobility in situ.

  • First, is an application in developing the actin or other component, for a biotarget and then, to be able to follow it as

(a) a biomarker either for diagnosis, or

(b) for the potential treatment prediction of disease free survival.

  • Second, is mostly in the context of MI, for which there is an abundance of work to reference, and a substantial body of knowledge about

(a) treatment and long term effects of diet, exercise, and

(b) underlying effects of therapeutic drugs.

Microtubule-Associated Protein Assembled on Polymerized Microtubules

(This article has a great 3D visualization of a microtuble structure as well as description of genetic diseases which result from mutations in tubulin and effects on intracellular trafficking of proteins.

A latticework of tiny tubes called microtubules gives your cells their shape and also acts like a railroad track that essential proteins travel on. But if there is a glitch in the connection between train and track, diseases can occur. In the November 24, 2015 issue of PNAS, Tatyana Polenova, Ph.D., Professor of Chemistry and Biochemistry, and her team at the University of Delaware (UD), together with John C. Williams, Ph.D., Associate Professor at the Beckman Research Institute of City of Hope in Duarte, California, reveal for the first time — atom by atom — the structure of a protein bound to a microtubule. The protein of focus, CAP-Gly, short for “cytoskeleton-associated protein-glycine-rich domains,” is a component of dynactin, which binds with the motor protein dynein to move cargoes of essential proteins along the microtubule tracks. Mutations in CAP-Gly have been linked to such neurological diseases and disorders as Perry syndrome and distal spinal bulbar muscular dystrophy.

 

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Lesson 4 Cell Signaling And Motility: G Proteins, Signal Transduction: Curations and Articles of reference as supplemental information: #TUBiol3373

Curator: Stephen J. Williams, Ph.D.

Updated 7/15/2019

Below please find the link to the Powerpoint presentation for lesson #4 for #TUBiol3373.  The lesson first competes the discussion on G Protein Coupled Receptors, including how cells terminate cell signals.  Included are mechanisms of receptor desensitization.  Please NOTE that desensitization mechanisms like B arrestin decoupling of G proteins and receptor endocytosis occur after REPEATED and HIGH exposures to agonist.  Hydrolysis of GTP of the alpha subunit of G proteins, removal of agonist, and the action of phosphodiesterase on the second messenger (cAMP or cGMP) is what results in the downslope of the effect curve, the termination of the signal after agonist-receptor interaction.

 

Click below for PowerPoint of lesson 4

Powerpoint for lesson 4

 

Please Click below for the papers for your Group presentations

paper 1: Membrane interactions of G proteins and other related proteins

paper 2: Macaluso_et_al-2002-Journal_of_Cellular_Physiology

paper 3: Interactions of Ras proteins with the plasma membrane

paper 4: Futosi_et_al-2016-Immunological_Reviews

 

Please find related article on G proteins and Receptor Tyrosine Kinases on this Open Access Online Journal

G Protein–Coupled Receptor and S-Nitrosylation in Cardiac Ischemia and Acute Coronary Syndrome

Action of Hormones on the Circulation

Newer Treatments for Depression: Monoamine, Neurotrophic Factor & Pharmacokinetic Hypotheses

VEGF activation and signaling, lysine methylation, and activation of receptor tyrosine kinase

 

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Lesson 9 Cell Signaling:  Curations and Articles of reference as supplemental information for lecture section on WNTs: #TUBiol3373

Stephen J. Wiilliams, Ph.D: Curator

UPDATED 4/23/2019

This has an updated lesson on WNT signaling.  Please click on the following and look at the slides labeled under lesson 10

cell motility 9b lesson_2018_sjw

Remember our lessons on the importance of signal termination.  The CANONICAL WNT signaling (that is the β-catenin dependent signaling)

is terminated by the APC-driven degradation complex.  This leads to the signal messenger  β-catenin being degraded by the proteosome.  Other examples of growth factor signaling that is terminated by a proteosome-directed include the Hedgehog signaling system, which is involved in growth and differentiation as well as WNTs and is implicated in various cancers.

A good article on the Hedgehog signaling pathway is found here:

The Voice of a Pathologist, Cancer Expert: Scientific Interpretation of Images: Cancer Signaling Pathways and Tumor Progression

All images in use for this article are under copyrights with Shutterstock.com

Cancer is expressed through a series of transformations equally involving metabolic enzymes and glucose, fat, and protein metabolism, and gene transcription, as a result of altered gene regulatory and transcription pathways, and also as a result of changes in cell-cell interactions.  These are embodied in the following series of graphics.

Figure 1: Sonic_hedgehog_pathwaySonic_hedgehog_pathway

The Voice of Dr. Larry

The figure shows a modification of nuclear translocation by Sonic hedgehog pathway. The hedgehog proteins have since been implicated in the development of internal organs, midline neurological structures, and the hematopoietic system in humans. The Hh signaling pathway consists of three main components: the receptor patched 1 (PTCH1), the seven transmembrane G-protein coupled receptor smoothened (SMO), and the intracellular glioma-associated oncogene homolog (GLI) family of transcription factors.5The GLI family is composed of three members, including GLI1 (gene activating), GLI2 (gene activating and repressive), and GLI3 (gene repressive).6 In the absence of an activating signal from either Shh, Ihh or Dhh, PTCH1 exerts an inhibitory effect on the signal transducer SMO, preventing any downstream signaling from occurring.7 When Hh ligands bind and activate PTCH1, the inhibition on SMO is released, allowing the translocation of SMO into the cytoplasm and its subsequent activation of the GLI family of transcription factors.

 

And from the review of  Elaine Y. C. HsiaYirui Gui, and Xiaoyan Zheng   Regulation of Hedgehog Signaling by Ubiquitination  Front Biol (Beijing). 2015 Jun; 10(3): 203–220.

the authors state:

Finally, termination of Hh signaling is also important for controlling the duration of pathway activity. Hh induced ubiquitination and degradation of Ci/Gli is the most well-established mechanism for limiting signal duration, and inhibiting this process can lead to cell patterning disruption and excessive cell proliferation (). In addition to Ci/Gli, a growing body of evidence suggests that ubiquitination also plays critical roles in regulating other Hh signaling components including Ptc, Smo, and Sufu. Thus, ubiquitination serves as a general mechanism in the dynamic regulation of the Hh pathway.

Overview of Hedgehog signaling showing the signal termination by ubiquitnation and subsequent degradation of the Gli transcriptional factors. obtained from Oncotarget 5(10):2881-911 · May 2014. GSK-3B as a Therapeutic Intervention in Cancer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note that in absence of Hedgehog ligands Ptch inhibits Smo accumulation and activation but upon binding of Hedgehog ligands (by an autocrine or paracrine fashion) Ptch is now unable to inhibit Smo (evidence exists that Ptch is now targeted for degradation) and Smo can now inhibit Sufu-dependent and GSK-3B dependent induced degradation of Gli factors Gli1 and Gli2.  Also note the Gli1 and Gli2 are transcriptional activators while Gli3 is a transcriptional repressor.

UPDATED 4/16/2019

Please click on the following links for the Powerpoint presentation for lesson 9.  In addition click on the mp4 links to download the movies so you can view them in Powerpoint slide 22:

cell motility 9 lesson_SJW 2019

movie file 1:

Tumorigenic but noninvasive MCF-7 cells motility on an extracellular matrix derived from normal (3DCntrol) or tumor associated (TA) fibroblasts.  Note that TA ECM is “soft” and not organized and tumor cells appear to move randomly if  much at all.

Movie 2:

 

Note that these tumorigenic and invasive MDA-MB-231 breast cancer cells move in organized patterns on organized ECM derived from Tumor Associated (TA) fibroblasts than from the ‘soft’ or unorganized ECM derived from normal  (3DCntrl) fibroblasts

 

The following contain curations of scientific articles from the site https://pharmaceuticalintelligence.com  intended as additional reference material  to supplement material presented in the lecture.

Wnts are a family of lipid-modified secreted glycoproteins which are involved in:

Normal physiological processes including

A. Development:

– Osteogenesis and adipogenesis (Loss of wnt/β‐catenin signaling causes cell fate shift of preosteoblasts from osteoblasts to adipocytes)

  – embryogenesis including body axis patterning, cell fate specification, cell proliferation and cell migration

B. tissue regeneration in adult tissue

read: Wnt signaling in the intestinal epithelium: from endoderm to cancer

And in pathologic processes such as oncogenesis (refer to Wnt/β-catenin Signaling [7.10]) and to your Powerpoint presentation

 

The curation Wnt/β-catenin Signaling is a comprehensive review of canonical and noncanonical Wnt signaling pathways

 

To review:

 

 

 

 

 

 

 

 

 

 

 

Activating the canonical Wnt pathway frees B-catenin from the degradation complex, resulting in B-catenin translocating to the nucleus and resultant transcription of B-catenin/TCF/LEF target genes.

Fig. 1 Canonical Wnt/FZD signaling pathway. (A) In the absence of Wnt signaling, soluble β-catenin is phosphorylated by a degradation complex consisting of the kinases GSK3β and CK1α and the scaffolding proteins APC and Axin1. Phosphorylated β-catenin is targeted for proteasomal degradation after ubiquitination by the SCF protein complex. In the nucleus and in the absence of β-catenin, TCF/LEF transcription factor activity is repressed by TLE-1; (B) activation of the canonical Wnt/FZD signaling leads to phosphorylation of Dvl/Dsh, which in turn recruits Axin1 and GSK3β adjacent to the plasma membrane, thus preventing the formation of the degradation complex. As a result, β-catenin accumulates in the cytoplasm and translocates into the nucleus, where it promotes the expression of target genes via interaction with TCF/LEF transcription factors and other proteins such as CBP, Bcl9, and Pygo.

NOTE: In the canonical signaling, the Wnt signal is transmitted via the Frizzled/LRP5/6 activated receptor to INACTIVATE the degradation complex thus allowing free B-catenin to act as the ultimate transducer of the signal.

Remember, as we discussed, the most frequent cancer-related mutations of WNT pathway constituents is in APC.

This shows how important the degradation complex is in controlling canonical WNT signaling.

Other cell signaling systems are controlled by protein degradation:

A.  The Forkhead family of transcription factors

Read: Regulation of FoxO protein stability via ubiquitination and proteasome degradation

B. Tumor necrosis factor α/NF κB signaling

Read: NF-κB, the first quarter-century: remarkable progress and outstanding questions

1.            Question: In cell involving G-proteins, the signal can be terminated by desensitization mechanisms.  How is both the canonical and noncanonical Wnt signal eventually terminated/desensitized?

We also discussed the noncanonical Wnt signaling pathway (independent of B-catenin induced transcriptional activity).  Note that the canonical and noncanonical involve different transducers of the signal.

Noncanonical WNT Signaling

Note: In noncanonical signaling the transducer is a G-protein and second messenger system is IP3/DAG/Ca++ and/or kinases such as MAPK, JNK.

Depending on the different combinations of WNT ligands and the receptors, WNT signaling activates several different intracellular pathways  (i.e. canonical versus noncanonical)

 

In addition different Wnt ligands are expressed at different times (temporally) and different cell types in development and in the process of oncogenesis. 

The following paper on Wnt signaling in ovarian oncogenesis shows how certain Wnt ligands are expressed in normal epithelial cells but the Wnt expression pattern changes upon transformation and ovarian oncogenesis. In addition, differential expression of canonical versus noncanonical WNT ligands occur during the process of oncogenesis (for example below the authors describe the noncanonical WNT5a is expressed in normal ovarian  epithelia yet WNT5a expression in ovarian cancer is lower than the underlying normal epithelium. However the canonical WNT10a, overexpressed in ovarian cancer cells, serves as an oncogene, promoting oncogenesis and tumor growth.

Wnt5a Suppresses Epithelial Ovarian Cancer by Promoting Cellular Senescence

Benjamin G. Bitler,1 Jasmine P. Nicodemus,1 Hua Li,1 Qi Cai,2 Hong Wu,3 Xiang Hua,4 Tianyu Li,5 Michael J. Birrer,6Andrew K. Godwin,7 Paul Cairns,8 and Rugang Zhang1,*

A.           Abstract

Epithelial ovarian cancer (EOC) remains the most lethal gynecological malignancy in the US. Thus, there is an urgent need to develop novel therapeutics for this disease. Cellular senescence is an important tumor suppression mechanism that has recently been suggested as a novel mechanism to target for developing cancer therapeutics. Wnt5a is a non-canonical Wnt ligand that plays a context-dependent role in human cancers. Here, we investigate the role of Wnt5a in regulating senescence of EOC cells. We demonstrate that Wnt5a is expressed at significantly lower levels in human EOC cell lines and in primary human EOCs (n = 130) compared with either normal ovarian surface epithelium (n = 31; p = 0.039) or fallopian tube epithelium (n = 28; p < 0.001). Notably, a lower level of Wnt5a expression correlates with tumor stage (p = 0.003) and predicts shorter overall survival in EOC patients (p = 0.003). Significantly, restoration of Wnt5a expression inhibits the proliferation of human EOC cells both in vitro and in vivo in an orthotopic EOC mouse model. Mechanistically, Wnt5a antagonizes canonical Wnt/β-catenin signaling and induces cellular senescence by activating the histone repressor A (HIRA)/promyelocytic leukemia (PML) senescence pathway. In summary, we show that loss of Wnt5a predicts poor outcome in EOC patients and Wnt5a suppresses the growth of EOC cells by triggering cellular senescence. We suggest that strategies to drive senescence in EOC cells by reconstituting Wnt5a signaling may offer an effective new strategy for EOC therapy.

Oncol Lett. 2017 Dec;14(6):6611-6617. doi: 10.3892/ol.2017.7062. Epub 2017 Sep 26.

Clinical significance and biological role of Wnt10a in ovarian cancer. 

Li P1Liu W1Xu Q1Wang C1.

Ovarian cancer is one of the five most malignant types of cancer in females, and the only currently effective therapy is surgical resection combined with chemotherapy. Wnt family member 10A (Wnt10a) has previously been identified to serve an oncogenic function in several tumor types, and was revealed to have clinical significance in renal cell carcinoma; however, there is still only limited information regarding the function of Wnt10a in the carcinogenesis of ovarian cancer. The present study identified increased expression levels of Wnt10a in two cell lines, SKOV3 and A2780, using reverse transcription-polymerase chain reaction. Functional analysis indicated that the viability rate and migratory ability of SKOV3 cells was significantly inhibited following Wnt10a knockdown using short interfering RNA (siRNA) technology. The viability rate of SKOV3 cells decreased by ~60% compared with the control and the migratory ability was only ~30% of that in the control. Furthermore, the expression levels of β-catenin, transcription factor 4, lymphoid enhancer binding factor 1 and cyclin D1 were significantly downregulated in SKOV3 cells treated with Wnt10a-siRNA3 or LGK-974, a specific inhibitor of the canonical Wnt signaling pathway. However, there were no synergistic effects observed between Wnt10a siRNA3 and LGK-974, which indicated that Wnt10a activated the Wnt/β-catenin signaling pathway in SKOV3 cells. In addition, using quantitative PCR, Wnt10a was overexpressed in the tumor tissue samples obtained from 86 patients with ovarian cancer when compared with matching paratumoral tissues. Clinicopathological association analysis revealed that Wnt10a was significantly associated with high-grade (grade III, P=0.031) and late-stage (T4, P=0.008) ovarian cancer. Furthermore, the estimated 5-year survival rate was 18.4% for patients with low Wnt10a expression levels (n=38), whereas for patients with high Wnt10a expression (n=48) the rate was 6.3%. The results of the present study suggested that Wnt10a serves an oncogenic role during the carcinogenesis and progression of ovarian cancer via the Wnt/β-catenin signaling pathway.

Targeting the Wnt Pathway includes curations of articles related to the clinical development of Wnt signaling inhibitors as a therapeutic target in various cancers including hepatocellular carcinoma, colon, breast and potentially ovarian cancer.

 

2.         Question: Given that different Wnt ligands and receptors activate different signaling pathways, AND  WNT ligands  can be deferentially and temporally expressed  in various tumor types and the process of oncogenesis, how would you approach a personalized therapy targeting the WNT signaling pathway?

3.         Question: What are the potential mechanisms of either intrinsic or acquired resistance to Wnt ligand antagonists being developed?

 

Other related articles published in this Open Access Online Scientific Journal include the following:

Targeting the Wnt Pathway [7.11]

Wnt/β-catenin Signaling [7.10]

Cancer Signaling Pathways and Tumor Progression: Images of Biological Processes in the Voice of a Pathologist Cancer Expert

e-Scientific Publishing: The Competitive Advantage of a Powerhouse for Curation of Scientific Findings and Methodology Development for e-Scientific Publishing – LPBI Group, A Case in Point 

Electronic Scientific AGORA: Comment Exchanges by Global Scientists on Articles published in the Open Access Journal @pharmaceuticalintelligence.com – Four Case Studies

 

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“Minerals in Medicine” –  40 Minerals that are crucial to Human Health and Biomedicine: Exhibit by NIH Clinical Center and The Smithsonian Institution National Museum of Natural History

Reporter: Aviva Lev-Ari, PhD, RN

 

Friday, September 9, 2016

NIH Clinical Center and The Smithsonian Institution partner to launch Minerals in Medicine Exhibition

What

The National Institutes of Health Clinical Center, in partnership with The Smithsonian Institution National Museum of Natural History, will open a special exhibition of more than 40 minerals that are crucial to human health and biomedicine. “Minerals in Medicine” is designed to enthrall and enlighten NIH Clinical Center’s patients, their loved ones, and the NIH community. Media are invited into America’s Research Hospital, the NIH Clinical Center, to experience this unique exhibition during a ribbon cutting ceremony on Monday September 12 at 4pm.

Beyond taking in the minerals’ arresting beauty, spectators can learn about their important role in keeping the human body healthy, and in enabling the creation of life-saving medicines and cutting edge medical equipment that is used in the NIH Clinical Center and healthcare facilities worldwide. The exhibition, which is on an eighteen-month loan from the National Museum of Natural History, includes specimens that were handpicked from the museum’s vast collection by NIH physicians in partnership with Smithsonian Institution geologists. Some of the minerals on display were obtained regionally as they are part of the Maryland and Virginia landscape.

Who

  • John I. Gallin, M.D., Director of the NIH Clinical Center
  • Jeffrey E. Post, Ph.D., Smithsonian Institution National Museum of Natural History, Chair of the Department of Mineral Sciences and Curator of the National Gem and Mineral Collection

When

Monday, September 12, 2016, 4:00 – 5:00 p.m.

Where

NIH Clinical Center (Building 10), 10 Center Drive, Bethesda, MD, 20892; 1st Floor near Admissions

How

RSVP encouraged, but not required, to attend in person. NIH Visitors Map: http://www.ors.od.nih.gov/maps/Pages/NIH-Visitor-Map.aspx

About the NIH Clinical Center: The NIH Clinical Center is the clinical research hospital for the National Institutes of Health. Through clinical research, clinician-investigators translate laboratory discoveries into better treatments, therapies and interventions to improve the nation’s health. More information: http://clinicalcenter.nih.gov.

About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

SOURCE

https://www.nih.gov/news-events/news-releases/nih-clinical-center-smithsonian-institution-partner-launch-minerals-medicine-exhibition

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Bisphosphonates and Bone Metastasis [6.3.1]

Curator: Stephen J. Williams, Ph.D.

bisophosphonates chemical

General Structure of Bisphosphonates

One of the hallmarks of advanced cancer is the ability to metastasize (tumor cells migrating from primary tumor and colonize in a different anatomical site in the body) and many histologic types of primary tumors have the propensity to metastasize to the bone. One of the frequent complications occurring from bone metastasis is bone fractures and severe pain associated with these cancer-associated bone fractures. An additional problem is cancer-associated hypercalcemia, which may or may not be dependent on bone-metastasis. The main humoral factor associated with cancer-related hypercalcemia is parathyroid hormone–related protein, which is produced by many solid tumors (Paget’s disease). Parathyroid hormone–related protein increases calcium by activating parathyroid hormone receptors in tissue, which results in osteoclastic bone resorption; it also increases renal tubular resorption of calcium {see (1) Bower reference for more information). This curation involves three areas:

  1. The Changing Views How Bone Remodeling Occurs
  2. Early Development of Agents that Alter Bone Remodeling and Early Use in Cancer Patients
  3. Recent Developments Regarding Use of Bisphosphonates in Cancer Patients

As there are numerous articles (1360; more than to manually curate) on “bone”, “metastasis” and “bisphosphonates” the following link is to a Pubmed search on the terms

http://www.ncbi.nlm.nih.gov/pubmed/?term=bone+metastasis+bisphosphonates

In addition there are subset searches to show use of bisphosphonates in common cancers and files given below with numbers of articles:

Search terms with Pubmed link # citations
bone metastasis bisphosphonates 1360
+ breast 559
+ prostate 349
+ colon 9
+ lung 222
  1. The Changing Views How Bone Remodeling Occurs

Bone remodeling (or bone metabolism) is a lifelong process where mature bone tissue is removed from the skeleton (a process called bone resorption) and new bone tissue is formed (a process called ossification or new bone formation). These processes also control the reshaping or replacement of bone following injuries like fractures but also micro-damage, which occurs during normal activity. Remodeling responds also to functional demands of the mechanical loading.

In the first year of life, almost 100% of the skeleton is replaced. In adults, remodeling proceeds at about 10% per year.[1]

An imbalance in the regulation of bone remodeling’s two sub-processes, bone resorption and bone formation, results in many metabolic bone diseases, such as osteoporosis. Two main types of cells are responsible for bone metabolism: osteoblasts (which secrete new bone), and osteoclasts (which break bone down). The structure of bones as well as adequate supply of calcium requires close cooperation between these two cell types and other cell populations present at the bone remodeling sites (ex. immune cells).[4] Bone metabolism relies on complex signaling pathways and control mechanisms to achieve proper rates of growth and differentiation. These controls include the action of several hormones, including parathyroid hormone (PTH), vitamin D, growth hormone, steroids, and calcitonin, as well as several bone marrow-derived membrane and soluble cytokines and growth factors (ex. M-CSF, RANKL, VEGF, IL-6 family…). It is in this way that the body is able to maintain proper levels of calcium required for physiological processes.

Subsequent to appropriate signaling, osteoclasts move to resorb the surface of the bone, followed by deposition of bone by osteoblasts. Together, the cells that are responsible for bone remodeling are known as the basic multicellular unit (BMU), and the temporal duration (i.e. lifespan) of the BMU is referred to as the bone remodeling period.

For a good review on bone remodeling please see Bone remodelling in a nutshell

boneremodelPTHumich

bone remodeling 3

  1. Early Development of Agents that Alter Bone Remodeling and Early Use in Cancer Patients

Bisphosphonates had been first synthesized in the late 1800’s yet their development and approval for the indication of osteoporosis occurred over 100 years later, in the 1990’s. For a good review on the history of bisphosphonates please see the following review:

Historical perspectives on the clinical development of bisphosphonates in the treatment of bone diseases. Francis MD1, Valent DJ. J Musculoskelet Neuronal Interact. 2007 Jan-Mar;7(1):2-8.

For a good reference on bisphosphonates as a class, as well as indication, contraindication and side effects see University of Washington web page at http://courses.washington.edu/bonephys/opbis.html

 

Please view slideshow in the following link: The Evolving Role of Bisphosphonates for Cancer Treatment-Induced Bone Loss presentation by Richard L. Theriault, DO, MBA at MD Anderson Cancer Center

bisphosphonatecancerslide1

  1. Recent Developments Regarding Use of Bisphosphonates in Cancer Patients

Bone Metastasis Treatment with Bisphosphonates; A review form OncoLink

Source: From University of Pennsylvania OncoLink® at http://www.oncolink.org/types/article.cfm?c=708&id=9629

Julia Draznin Maltzman, MD and Modified by Lara Bonner Millar, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: December 18, 2014

Introduction

Bone metastases are a common complication of advanced cancer. They are especially prevalent (up to 70%) in breast and prostate cancer. Bone metastases can cause severe pain, bone fractures, life-threatening electrolyte imbalances, and nerve compression syndromes. The pain and neurologic dysfunction may be difficult to treat and significantly compromises the patients’ quality of life. Bone metastases usually signify advanced, often incurable disease.

Osteolytic vs. osteoblastic

Bony metastases are characterized as being either osteolytic or osteoblastic. Osteolytic means that the tumor caused bone break down or dissolution. This usually results in loss of calcium from bone. On X-rays these are seen as holes called “lucencies” within the bone. Diffuse osteolytic lesions are most characteristic of a blood cancer called Multiple Myeloma, however they may be present in patients with many other types of cancer.

Osteoblastic bony lesions, by contrast, are characterized by increased bone production. The tumor somehow signals to the bone to overproduce bone cells and result in rigid, inflexible bone formation. The cancer that typically causes osteoblastic bony lesions is prostate cancer. Most cancers result in either osteolytic or osteoblastic bony changes, but some malignancies can lead to both. Breast cancer patients usually develop osteolytic lesions, although at least 15-20 percent can have osteoblastic pathology.

Why the bone?

The bone is a common site of metastasis for many solid tissue cancers including prostate, breast, lung, kidney, stomach, bladder, uterus, thyroid, colon and rectum. Researchers speculate that this may be due to the high blood flow to the bone and bone marrow. Once cancer cells gain access to the blood vessels, they can travel all over the body and usually go where there is the highest flow of blood. Furthermore, tumor cells themselves secrete adhesive molecules that can bind to the bone marrow and bone matrix. This molecular interaction can cause the tumor to signal for increased bone destruction and enhance tumor growth within the bone. A recent scientific discovery showed that the bone is actually a rich source of growth factors. These growth factors signal cells to divide, grow, and mature. As the cancer attacks the bone, these growth factors are released and serve to further stimulate the tumor cells to grow. This results in a self-generating growth loop.

What are the symptoms of bone metastasis?

It must be recognized that the symptoms of bone metastasis can mimic many other disease conditions. Most people with bony pain do not have bone metastasis. That being noted, the most common symptom of a metastasis to the bone is pain. Another common presentation is a bone fracture without any history of trauma. Fracture is more common in lytic metastases than blastic metastases.

Some people with more advanced disease may come to medical attention because of numbness and tingling sensation in their feet and legs. They may have bowel and bladder dysfunction – either losing continence to urine and/or stool, or severe constipation and urinary retention. Others may complain of leg weakness and difficulty moving their legs against gravity. This would imply that there is tumor impinging on the spinal cord and compromising the nerves. This is considered an emergency called spinal cord compression, and requires immediate medical attention. Another less common presentation of metastatic disease to the bone is high levels of calcium in the body. High calcium can make patients constipated, result in abdominal pain, and at very high levels, can lead to confusion and mental status changes.

Diagnosis of bone metastasis

Once a patient experiences any of the symptoms of bone metastasis, various tests can be done to find the true cause. In some cases bone metastasis can be detected before the symptoms arise. X-rays, bone scans, and MRIs are used to diagnose this complication of cancer. X-rays are especially helpful in finding osteolytic lesions. These often appear as “holes” or dark spots in the bone on the x-ray film. Unfortunately, bone metastases often do not show up on plain x-rays until they are quite advanced. By contrast, a bone scan can detect very early bone metastases. This test is done by injecting the patient with a small amount of radio-tracing material in the vein. Special x-rays are taken sometime after the injection. The radiotracer will preferentially go to the site of disease and will appear as a darker, denser, area on the film. Because this technique is so sensitive, sometimes infections, arthritis, and old fractures can appear as dark spots on the bone scan and may be difficult to differentiate from a true cancer. Bone scans are also used to follow patients with known bone metastasis. Sometimes CT scan images can show if a cancer has spread to the bone. An MRI is most useful when examining nerve roots suspected of being compressed by tumor or bone fragments due to tumor destruction. It is used most often in the setting of spinal cord compromise.

There are no real blood tests that are currently used to diagnose a bone metastasis. There are, however, a number of blood tests that a provider can obtain that may suggest the presence of bone lesions, but the diagnosis rests with the combination of radiographic evidence, clinical picture, and natural history of the malignancy. For example, elevated levels of calcium or an enzyme called alkaline phosphatase can be related to bone metastasis, but these lab tests alone are insufficient to prove their presence.

Treatment

The best treatment for bony metastasis is the treatment of the primary cancer. Therapies may include chemotherapy, hormone therapy, radiation therapy, immunotherapy, or treatment with monoclonal antibodies. Pain is often treated with narcotics and other pain medications, such as non-steroidal anti-inflammatory agents. Physical therapy may be helpful and surgery may have an important role if the cancer resulted in a fracture of the bone.

Bisphosphonates

Bisphosphonates are s category of medications that decrease pain from bone metastasis and may improve overall bone health. Bisphosphonates man-made versions of a naturally occurring compound called pyrophosphate that prevents bone breakdown. They are a class of medications widely used in the treatment and prevention of osteoporosis and certain other bone diseases (such as Paget’s Disease), as well as in the treatment of elevated blood calcium. These drugs suppress bone breakdown by cells called osteoclasts, and, can indirectly stimulate the bone forming cells called osteoblasts. It is for this reason, and for the fact that bisphosphonates are very effective in relieving bone pain associated with metastatic disease, that they have transitioned to the oncology arena. However, treatment of bone metastases is not curative. There is increasing evidence that bisphosphonates can prevent bony complications in some metastatic cancers and may even improve survival in some cancers. Most researchers agree that these drugs are more helpful in osteolytic lesions and less so in osteoblastic metastasis in terms of bone restoration and health, but the bisphosphonates are able to alleviate pain associated with both types of lesions. The appropriate time to start treatment is once a bone metastasis has been identified on imaging.

Bisphosphonates can be given either orally or intravenously. The latter is the preferred route of administration for many oncologists as it is given monthly as a short infusion and does not have the gastrointestinal side effects that the oral bisphosphonates have. There are currently two approved and commonly used IV bisphosphonates –Pamidronate disodium (Aredia, Novartis) and zolendronic acid (Zometa, Novartis). Their side effect profile is fairly mild and includes a flu-like reaction during the first 48 hours after the infusion, kidney impairment and osteonecrosis of the jaw with long term use. Patients with renal impairment may not be candidates for this therapy.

Bisphophonates may have some level of anti-tumor activity in breast cancer. A recent Phase III clinical trial revealed that the addition of Zometa to endocrine therapy, improves disease-free survival, but not overall survival, in pre-menopausal patients with estrogen-receptor postive early breast cancer. Another trial called AZURE found no effect from the bisphosphonate zolendronic acid (Zometa, Novartis) on the recurrence of breast cancer or on overall survival. However, several other studies on bisphosphonates and breast cancer are ongoing, and for now, their use is not recommended in patients without metastases.

In addition to bisphosphonates, osteoclast inhibition can also be achieved through other means. Another medication, Denosumab (XGEVA, Amgen), targets a receptor called receptor activator of nuclear factor kappa B ligand (RANKL), is able to block osteoclast formation. A few studies comparing Denosumab to bisphosphonates have found Denosumab results in a longer time to skeletal events, on the order of a few months, compared to bisphosphonates, however many experts believe that the evidence is not strong enough to support one class of drug over another. The most common side effects of Denosumab are fatigue or asthenia, hypophosphatemia, hypocalcemia and nausea. Patients receiving bisphosphonates or denosumab should also be taking calcium and vitamin D supplementation.

The future

Skeletal metastases remain one of the more debilitating problems for cancer patients. Research is ongoing to identify the molecular mechanisms that result in both osteolytic and osteoblastic bone lesions. Perhaps the use of proteomics and gene array data may permit us to identify some factors specific to the tumor or to the bony lesion itself that could be used as therapeutic targets to teat or even prevent this complication.

In summary

  •  there is well established evidence in preclinical models that bisphosphonates:reduce the total tumor burden in bone
  • it is unclear as to the mechanisms of this preclinical finding as bisphosphonates have been shown to directly have antitumor activity
  • as the review by Holen I1, Coleman RE.show “Bisphosphonates as treatment of bone metastases” (abstract given below) there is conflicting clinical evidence of this effect found in preclinical models

Accelerated bone loss is a common clinical feature of advanced breast cancer, and anti-resorptive bisphosphonates are the current standard therapy used to reduce the number and frequency of skeletal-related complications experienced by patients. Bisphosphonates are potent inhibitors of bone resorption, acting by inducing osteoclast apoptosis and thereby preventing the development of cancer-induced bone lesions. In clinical use bisphosphonates are mainly considered to be bone-specific agents, but anti-tumour effects have been reported in a number of in vitro and in vivo studies. By combining bisphosphonates with chemotherapy agents, growth and progression of breast cancer bone metastases can be virtually eliminated in model systems. Recent clinical trials have indicated that there may be additional benefits from bisphosphonate treatment, including positive effects on recurrence and survival when added to standard endocrine therapy. Whereas the ability of bisphosphonates to reduce cancer-induced bone disease is well established, their potential direct anti-tumour effect remain controversial. Ongoing clinical trials will establish whether bisphosphonates can inhibit the development of bone metastases in high-risk breast cancer patients. This review summarizes the main studies that have investigated the effects of bisphosphonates, alone and in combination with other anti-cancer agents, using in vivo model systems of breast cancer bone metastases. We also give an overview of the use of bisphosphonates in the treatment of breast cancer, including examples of key clinical trials. The potential side effects and future clinical applications of bisphosphonates will be outlined.

References

  1. Bower M, Cox S. Endocrine and metabolic complications of advanced cancer. In: Doyle D, Hanks G, Cherny NI, Calman K, editors. Oxford textbook of palliative medicine. 3rd ed. New York, NY: Oxford University Press; 2004. p. 688-90.

Henry DH, Costa L, Goldwasser F, et al. Randomized, double-blind study of denosumab versus zoledronic acid in the treatment of bone metastases in patients with advanced cancer (excluding breast and prostate cancer) or multiple myeloma. J Clin Oncol. 2011;29(9):1125-32.

Van Poznak CH, Temin S, Yee GC, et al. American Society of Clinical Oncology executive summary of the clinical practice guideline update on the role of bone-modifying agents in metastatic breast cancer. J Clin Oncol. 2011;29(9):1221-7.

West, H. Denosumab for prevention of skeletal-related events in patients with bone metastases from solid tumors: incremental benefit, debatable value. J Clin Oncol. 2011;29(9):1095-8.

Gnant M, Mlineritsch B, Schippinger W et al.: Endocrine therapy plus zoledronic acid in premenopausal breast cancer. N Engl J Med. 360(7),679–691 (2009).

Treatment Guidelines by Cancer Organizations

ASCO Issues Updated Guideline on the Role of Bone-Modifying Agents in the Prevention and Treatment of Bone Metastases in Patients with Metastatic Breast Cancer

For Immediate Release

February 22, 2011

Contact:

Steven Benowitz
571-483-1370
steven.benowitz@asco.org

ALEXANDRIA, Va. – The American Society of Clinical Oncology (ASCO) today issued an update to its clinical practice guideline on the use of bone-modifying agents, in particular, osteoclast inhibitors, to prevent and treat skeletal complications from bone metastases in patients with metastatic breast cancer. The new guideline includes recommendations on the use of a new drug option, denosumab (Xgeva), and addresses osteonecrosis of the jaw, an uncommon condition that may occur in association with bone-modifying agents. The updated guideline also provides new recommendations on monitoring of patients who undergo treatment with bone-modifying agents and highlights priorities for future research on these drugs.

ASCO’s Bisphosphonates in Breast Cancer Panel conducted a systematic review of the medical literature to develop the new recommendations. The updated guideline, American Society of Clinical Oncology Clinical Practice Guideline Update on the Role of Bone-Modifying Agents in Metastatic Breast Cancer, was published online today in the Journal of Clinical Oncology.

The guideline recommends that patients with breast cancer who have evidence of bone metastases be given one of three agents – denosumab, pamidronate or zoledronic acid – approved by the U.S. Food and Drug Administration. It does not support use of any one drug over the others. These drugs are all considered osteoclast inhibitors, but they belong to different drug families: pamidronate and zoledronic acid are part of a class of drugs called bisphosphonates, while denosumab is a monoclonal antibody that targets receptor activator of nuclear factor-kappa beta ligand (RANKL).

The guideline also recommends against initiating bone-modifying agents in the absence of bone metastases outside of a clinical trial. It notes that an abnormal bone scan result alone, without confirmation by a radiograph, CT or MRI scan, is not sufficient evidence to support treatment with these drugs.

“The updated recommendations take into account recent progress in controlling potential bone damage in metastatic breast cancer,” said Catherine Van Poznak, MD, co-chair of the Bisphosphonates in Breast Cancer Panel and assistant professor of medicine at the University of Michigan. “We’ve established that a growing number of osteoclast inhibitors can have a positive effect and decrease of the risk of skeletal-related events in women with bone metastases. Because many factors – including medical and economic – must be considered when selecting a therapy for an individual, it’s good to have several effective choices.”

Bone is one of the most common sites to which breast cancer spreads. Bone metastases occur in approximately 70 percent of patients with metastatic disease. These metastases can cause bone cells (osteoclasts) to become overactive, which can result in excessive bone loss, disrupting the bone architecture and causing skeletal-related events (SREs), such as fracture, the need for surgery or radiation therapy to bone, spinal cord compression and hypercalcemia of malignancy.

This document updates guideline recommendations that were first issued in 2000 and revised in 2003, and focused on the use of bisphosphonates. The current guideline uses the more inclusive term, bone-modifying agents, to reflect a wider category of therapeutic agents such as monoclonal antibodies that use different mechanisms of action to prevent and treat damage from bone metastases. The guideline notes that research remains to be conducted to address several areas where questions remain.

“The guideline considers new data in a variety of areas, including studies showing that denosumab has equivalent effectiveness compared with other currently available drug therapies,” explained bisphosphonates panel co-chair Jamie Von Roenn, MD, professor of medicine at Northwestern University. “The guideline also provides guidance on preventing a rare, but significant complication of therapy with bone-modifying agents, osteonecrosis of the jaw.”

Denosumab is a human monoclonal antibody that targets a receptor, RANKL, involved in the regulation of bone remodeling. The guideline cites evidence from a randomized Phase III trial showing that denosumab appears to be comparable to zoledronic acid in reducing the risk of SREs in women with bone metastases from breast cancer. Denosumab is given subcutaneously, and can have side effects such as hypocalcemia.

The guideline also addresses the recently discovered osteonecrosis of the jaw. The first reports of this degenerative condition were published in the medical and dental literature in 2003. The committee recommended that all patients with breast cancer get dental evaluations and receive preventive dentistry care before beginning treatment with bone-modifying osteoclast inhibitors.

The panel updated its recommendations regarding the effects of bisphosphonates on kidney function, particularly for those taking either pamidronate or zoledronic acid, which have been associated with deteriorating kidney function. It said that clinicians should monitor serum creatinine clearance prior to each dose of pamidronate or zoledronic acid according to FDA-approved labeling.

The panel did not recommend using biochemical markers to monitor bone-modifying agent effectiveness and use outside of a clinical trial.

While many of the 2003 recommendations remain the same, the guideline notes several research directions to be addressed, including:

  • Duration of therapy with bone modifying agents, and the timing or intervals between delivery.
  • The development of a risk index for SREs, and better ways to stratify patient risk of SRE or risk of toxicity from a bone-modifying agent. Individual risk may guide selection of timing for use of a bone-modifying agent therapy.
  • Trials specifically examining whether stage IV breast cancer patients who do not have evidence of bone metastases would benefit from bone-modifying agents.
  • The role of biomarkers in treatment selection and monitoring drug effectiveness.
  • Understanding the optimal dosing of calcium and vitamin D supplementation in patients treated with bone-modifying agents.

The meta-analysis from the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) was published in Lancet and suggested that “Adjuvant bisphosphonates reduce the rate of breast cancer recurrence in the bone and improve breast cancer survival, but there is definite benefit only in women who were postmenopausal when treatment began”.

Results

  • Of 18, 206 women in trials of 2-5 years of bisphosphonate3453 first recurrences, and 2106 subsequent deaths.
  • Overall, the reductions in recurrence (RR 0·94, 95% CI 0·87-1·01; 2p=0·08), distant recurrence (0·92, 0·85-0·99; 2p=0·03), and breast cancer mortality (0·91, 0·83-0·99; 2p=0·04) were of only borderline significance
  • Among premenopausal women, treatment had no apparent effect on any outcome, but among 11 767 postmenopausal women it produced highly significant reductions in recurrence (RR 0·86, 95% CI 0·78-0·94; 2p=0·002), distant recurrence (0·82, 0·74-0·92; 2p=0·0003), bone recurrence (0·72, 0·60-0·86; 2p=0·0002), and breast cancer mortality (0·82, 0·73-0·93; 2p=0·002). “This was iregardless of age or bisphosphonate type.

Lancet. 2015 Jul 23. pii: S0140-6736(15)60908-4. doi: 10.1016/S0140-6736(15)60908-4. Adjuvant bisphosphonate treatment in early breast cancer: meta-analyses of individual patient data from randomised trials.

Early Breast Cancer Trialists’ Collaborative Group (EBCTCG).

This Study was reported at the 36th Annual San Antonio Breast Cancer Symposium (SABCS): Abstract S4-07. Presented December 12, 2013 and Medscape Medical News journalist Kate Johnson covered the finding with author interviews in the following article:

Bisphosphonates: ‘New Addition’ to Breast Cancer Treatment?

Kate Johnson

December 13, 2013

Editors’ Recommendations

SAN ANTONIO — Adjuvant bisphosphonate treatment significantly improves breast cancer survival and reduces bone recurrence in postmenopausal women with early breast cancer, according to a meta-analysis reported here at the 36th Annual San Antonio Breast Cancer Symposium.

“We have finally defined a new addition to standard treatment,” announced lead investigator Robert Coleman, MD, professor of oncology at the University of Sheffield in the United Kingdom. He emphasized that, as hypothesized, the benefits of this therapy were confined to postmenopausal women.

“There is absolutely no effect on mortality in premenopausal women, with a hazard ratio [HR] of 1.0,” he reported. “But for postmenopausal women, we see a 17% reduction in the risk of death [HR, 0.83], which is highly statistically significant.”

In terms of the absolute benefit, bisphosphonates decreased the breast cancer mortality rate from 18.3% to 15.2% in postmenopausal women (P = .004).

The separation of benefit by menopausal status was also seen in the bone recurrence data.

In premenopausal women, there is no significant effect on bone recurrence (HR, 0.93), whereas in postmenopausal women, there was a 34% reduction. The difference was “highly significant,” said Dr. Coleman.

“I personally believe adjuvant bisphosphonates should be standard treatment in postmenopausal women with breast cancer,” said Michael Gnant, MD, professor of surgery at the Medical University of Vienna, who was one of the study investigators. He spoke during a plenary session before the results were formally announced. (Please click this LINK to See VIDEO Interview with Dr. Gnant)

“This is an important analysis,” said Rowan Chlebowski, MD, PhD, medical oncologist from the Harbor-UCLA Medical Center in Los Angeles.

“There will be a substantial increase in the use of bisphosphonates,” he told Medscape Medical News after the presentation.

“The only question is whether people will accept this analysis as the final word.” Dr. Chlebowski explained that some people might criticize the study as being a post hoc analysis of previous findings.

“You might find some mixed feelings about whether this should be accepted, but I think this will get people thinking,” he said. Dr. Chlebowski previously reported a large observational study that demonstrated that postmenopausal women taking oral bisphosphonates for osteoporosis had a significantly lower risk for breast cancer.

Bisphosphonates were originally indicated for the treatment of osteoporosis, and include agents such as alendronate (Fosamax, Merck), ibandronate (Boniva, Genentech), risedronate (Actonel, sanofi-aventis), and zoledronic acid (Reclast, Novartis). But they are also indicated for bone-related use in breast cancer patients, Dr. Chlebowski pointed out.

Because bisphosphonates “also have an indication for preventing bone loss associated with aromatase inhibitor use, they are already approved in this setting, and would prevent recurrences. It will be interesting to see if guideline panels” like these findings, he noted.

Why Postmenopausal Women Benefit

In the plenary session, Dr. Gnant acknowledged that the data on bisphosphonates to date have been mixed.

There are “many trials showing controversial results” for bisphosphonates in the context of breast cancer, he said. “When we put them all together in an unselected population, some show beneficial effects and some do not.”

Dr. Gnant explained why bisphosphonates appear to be effective in older but not younger women. “When you confine your analysis to the low-estrogen environment, postmenopausal women, or women rendered menopausal by ovarian function suppression, we see that all these trials show a consistent benefit for these patients,” he said.

“Essentially, this low-estrogen hypothesis as a prerequisite for adjuvant bisphosphonate activity means that we believe these treatments can silence the bone marrow microenvironment. However, this only translates to relevant clinical benefits in low-estrogen environments,” he added.

More Study Details

The meta-analysis involved 36 trials of adjuvant bisphosphonates in breast cancer with 17,791 pre- and postmenopausal women.

The primary outcomes of the study were time to distant recurrence, local recurrence, and new second primary breast cancer (ipsilateral or contralateral), time to first distant recurrence (ignoring any previous locoregional or contralateral recurrences), and breast cancer mortality.

Planned subgroup analyses based on hypotheses generated from previous findings included site of recurrence, site of first distant metastasis, menopausal status, and type and schedule of bisphosphonate therapy, said Dr. Coleman.

With bisphosphonate therapy, there was a nonsignificant 1% reduction in breast cancer recurrence at 10 years in postmenopausal women, compared with premenopausal women (25.4% vs 26.5%), and “a small borderline advantage” for distant recurrence (20.9% vs 22.3%), he reported.

However, there was a significant benefit of bisphosphonates in bone recurrence in postmenopausal women (6.9% vs 8.4%; P = .0009), with no effect on nonbone recurrence.

There was no impact of bisphosphonates on local recurrence or cancer in the contralateral breast.

For distant recurrence, there was a 3.5% absolute benefit in postmenopausal women (18.4% vs 21.9%; P = .0003); for distant recurrence, there is was a significant improvement of 2.9% in bone recurrence (5.9% vs 8.8%; P < .00001).

There was no significant reduction in first distant recurrence outside bone, and risk reductions were similar, irrespective of estrogen-receptor status, node status, or use or not of chemotherapy.

“Adjuvant bisphosphonates reduce bone metastases and improve survival in postmenopausal women,” concluded Dr. Coleman. “We have statistical security in this result, with a 34% reduction in the risk of bone recurrence (P = .00001), and a 17% — or 1 in 6 — reduction in the risk of breast cancer death (P =.004).”

The analysis struck a clear line between pre- and postmenopausal women — something that was revealed in a subgroup analysis the AZURE trial, which Dr. Coleman was involved in (N Engl J Med. 2011;365:1396-1405).

Because of this, he was asked about the validity of basing the current analysis on the AZURE hypothesis-generating population.

“We repeated the analysis without the AZURE patients, because they are the hypothesis-generating population, and the P values and risk reductions did not change,” he explained.

Source: Medscape Medical News at http://www.medscape.com/viewarticle/817787#vp_1

Updated on 10/20/2015: Other articles for reference on Bisphosphonates and Metastasis

Clin Exp Metastasis. 2015 Oct;32(7):689-702. doi: 10.1007/s10585-015-9737-y. Epub 2015 Aug 1.

Human breast cancer bone metastasis in vitro and in vivo: a novel 3D model system for studies of tumour cell-bone cell interactions.

Author information

  • 1Academic Unit of Clinical Oncology, Department of Oncology, Mellanby Centre for Bone Research, Medical School, University of Sheffield, Sheffield, S10 2RX, UK.
  • 2Department of Human Metabolism, Mellanby Centre for Bone Research, Medical School, University of Sheffield, Sheffield, S10 2RX, UK.
  • 3Academic Unit of Clinical Oncology, Department of Oncology, Mellanby Centre for Bone Research, Medical School, University of Sheffield, Sheffield, S10 2RX, UK. p.d.ottewell@sheffield.ac.uk.

Abstract

Bone is established as the preferred site of breast cancer metastasis. However, the precise mechanisms responsible for this preference remain unidentified. In order to improve outcome for patients with advanced breast cancer and skeletal involvement, we need to better understand how this process is initiated and regulated. As bone metastasis cannot be easily studied in patients, researchers have to date mainly relied on in vivo xenograft models. A major limitation of these is that they do not contain a human bone microenvironment, increasingly considered to be an important component of metastases. In order to address this shortcoming, we have developed a novel humanised bone model, where 1 × 10(5) luciferase-expressing MDA-MB-231 or T47D human breast tumour cells are seeded on viable human subchaodral bone discs in vitro. These discs contain functional osteoclasts 2-weeks after in vitro culture and positive staining for calcine 1-week after culture demonstrating active bone resorption/formation. In vitro inoculation of MDA-MB-231 or T47D cells colonised human bone cores and remained viable for <4 weeks, however, use of matrigel to enhance adhesion or a moving platform to increase diffusion of nutrients provided no additional advantage. Following colonisation by the tumour cells, bone discs pre-seeded with MDA-MB-231 cells were implanted subcutaneously into NOD SCID mice, and tumour growth monitored using in vivo imaging for up to 6 weeks. Tumour growth progressed in human bone discs in 80 % of the animals mimicking the later stages of human bone metastasis. Immunohistochemical and PCR analysis revealed that growing MDA-MB-231 cells in human bone resulted in these cells acquiring a molecular phenotype previously associated with breast cancer bone metastases. MDA-MB-231 cells grown in human bone discs showed increased expression of IL-1B, HRAS and MMP9 and decreased expression of S100A4, whereas, DKK2 and FN1 were unaltered compared with the same cells grown in mammary fat pads of mice not implanted with human bone discs.

Cancer. 2000 Jun 15;88(12 Suppl):2979-88.

Actions of bisphosphonate on bone metastasis in animal models of breast carcinoma.

Abstract

BACKGROUND:

Bone, which abundantly stores a variety of growth factors, provides a fertile soil for cancer cells to develop metastases by supplying these growth factors as a consequence of osteoclastic bone resorption. Accordingly, suppression of osteoclast activity is a primary approach to inhibit bone metastasis, and bisphosphonate (BP), a specific inhibitor of osteoclasts, has been widely used for the treatment of bone metastases in cancer patients. To obtain further insights into the therapeutic usefulness of BP, the authors studied the effects of BP on bone and visceral metastases in animal models of metastasis.

METHODS:

The authors used two animal models of breast carcinoma metastasis that they had developed in their laboratory over the last several years. One model uses female young nude mice in which inoculation of the MDA-MB-231 or MCF-7 human breast carcinoma cells into the left cardiac ventricle selectively develops osteolytic or osteosclerotic bone metastases, respectively. Another model uses syngeneic female mice (Balb/c) in which orthotopic inoculation of the 4T1 murine mammary carcinoma cells develops metastases in bone and visceral organs including lung, liver, and kidney.

RESULTS:

BP inhibited the development and progression of osteolytic bone metastases of MDA-MB-231 breast carcinoma through increased apoptosis in osteoclasts and breast carcinoma cells colonized in bone. In a preventative administration, however, BP alone increased the metastases to visceral organs with profound inhibition of bone metastases. However, combination of BP with anticancer agents such as uracil and tegafur or doxorubicin suppressed the metastases not only in bone but also visceral organs and prolonged the survival in 4T1 mammary tumor-bearing animals. Of interest, inhibition of early osteolysis by BP inhibited the subsequent development of osteosclerotic bone metastases of MCF-7 breast carcinoma.

CONCLUSIONS:

These results suggest that BP has beneficial effects on bone metastasis of breast carcinoma and is more effective when combined with anticancer agents. They also suggest that the animal models of bone metastasis described here allow us to design optimized regimen of BP administration for the treatment of breast carcinoma patients with bone and visceral metastases.

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Metabolic Genomics and Pharmaceutics, Vol. 1 of BioMed Series D available on Amazon Kindle


Metabolic Genomics and Pharmaceutics, Vol. 1 of BioMed Series D available on Amazon Kindle

Reporter: Stephen S Williams, PhD

 

Leaders in Pharmaceutical Business Intelligence would like to announce the First volume of their BioMedical E-Book Series D:

Metabolic Genomics & Pharmaceutics, Vol. I

SACHS FLYER 2014 Metabolomics SeriesDindividualred-page2

which is now available on Amazon Kindle at

http://www.amazon.com/dp/B012BB0ZF0.

This e-Book is a comprehensive review of recent Original Research on  METABOLOMICS and related opportunities for Targeted Therapy written by Experts, Authors, Writers. This is the first volume of the Series D: e-Books on BioMedicine – Metabolomics, Immunology, Infectious Diseases.  It is written for comprehension at the third year medical student level, or as a reference for licensing board exams, but it is also written for the education of a first time baccalaureate degree reader in the biological sciences.  Hopefully, it can be read with great interest by the undergraduate student who is undecided in the choice of a career. The results of Original Research are gaining value added for the e-Reader by the Methodology of Curation. The e-Book’s articles have been published on the Open Access Online Scientific Journal, since April 2012.  All new articles on this subject, will continue to be incorporated, as published with periodical updates.

We invite e-Readers to write an Article Reviews on Amazon for this e-Book on Amazon.

All forthcoming BioMed e-Book Titles can be viewed at:

https://pharmaceuticalintelligence.com/biomed-e-books/

Leaders in Pharmaceutical Business Intelligence, launched in April 2012 an Open Access Online Scientific Journal is a scientific, medical and business multi expert authoring environment in several domains of  life sciences, pharmaceutical, healthcare & medicine industries. The venture operates as an online scientific intellectual exchange at their website http://pharmaceuticalintelligence.com and for curation and reporting on frontiers in biomedical, biological sciences, healthcare economics, pharmacology, pharmaceuticals & medicine. In addition the venture publishes a Medical E-book Series available on Amazon’s Kindle platform.

Analyzing and sharing the vast and rapidly expanding volume of scientific knowledge has never been so crucial to innovation in the medical field. WE are addressing need of overcoming this scientific information overload by:

  • delivering curation and summary interpretations of latest findings and innovations on an open-access, Web 2.0 platform with future goals of providing primarily concept-driven search in the near future
  • providing a social platform for scientists and clinicians to enter into discussion using social media
  • compiling recent discoveries and issues in yearly-updated Medical E-book Series on Amazon’s mobile Kindle platform

This curation offers better organization and visibility to the critical information useful for the next innovations in academic, clinical, and industrial research by providing these hybrid networks.

Table of Contents for Metabolic Genomics & Pharmaceutics, Vol. I

Chapter 1: Metabolic Pathways

Chapter 2: Lipid Metabolism

Chapter 3: Cell Signaling

Chapter 4: Protein Synthesis and Degradation

Chapter 5: Sub-cellular Structure

Chapter 6: Proteomics

Chapter 7: Metabolomics

Chapter 8:  Impairments in Pathological States: Endocrine Disorders; Stress

                   Hypermetabolism and Cancer

Chapter 9: Genomic Expression in Health and Disease 

 

Summary 

Epilogue

 

 

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Archives of Medicine (AOM) to Publish from “Leaders in Pharmaceutical Business Intelligence (LPBI)” Open Access On-Line Scientific Journal http://pharmaceuticalintelligence.com

Reporter: Aviva Lev-Ari, PhD, RN

From our series on Calcium and Cardiovascular Diseases: A Series of Twelve Articles in Advanced Cardiology

AOM Editor-in Chief’s Article Selection and Assignment of manuscript number: iMedPub Journals includes the following and is updated as soon as additional selections are made

Part I:

Identification of Biomarkers that are Related to the Actin Cytoskeleton

Larry H Bernstein, MD, FCAP

  

Part II: has been been assigned the following manuscript number: iMedPub Journals-15-472

Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility

Larry H. Bernstein, MD, FCAP, Stephen Williams, PhD and Aviva Lev-Ari, PhD, RN

 

Part III:

Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease

Larry H. Bernstein, MD, FCAP, Stephen J. Williams, PhD
 and Aviva Lev-Ari, PhD, RN

  

Part IV: has been been assigned the following manuscript number: iMedPub Journals-15-471

The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, ArterialSmooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

 

Part V: has been been assigned the following manuscript number: iMedPub Journals-15-516

Heart, Vascular Smooth Muscle, Excitation-Contraction Coupling (E-CC), Cytoskeleton, Cellular Dynamics and Ca2 Signaling

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

 

Part VI:

Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD

Aviva Lev-Ari, PhD, RN

 

Part VII:

Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure – Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

  

Part VIII

Disruption of Calcium Homeostasis: Cardiomyocytes and Vascular Smooth Muscle Cells: The Cardiac and Cardiovascular Calcium Signaling Mechanism – Part VIII

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Part IX

Calcium-Channel Blockers, Calcium Release-related Contractile Dysfunction (Ryanopathy) and Calcium as Neurotransmitter Sensor – Part IX

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Part X – has been been assigned the following manuscript number: iMedPub Journals-15-517

Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of vesicles with cell membranes during Neurotransmission – Part X

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Part XI

Sensors and Signaling in Oxidative Stress – Part XI

Larry H. Bernstein, MD, FCAP

 

Part XII

Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD)) – Part XII

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

Part XIII has been been assigned the following manuscript number: iMedPub Journals-15-471

Ca2+-Stimulated Exocytosis:  The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

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Diabetes is caused by Leaky Calcium Channels in Pancreatic Beta Cells – research @Columbia University Medical Center: The Role of RyR2 in Regulation of Insulin Release and Glucose Homeostasis

Reporter: Aviva Lev-Ari, PhD, RN

Cellular Defect Linked to Diabetes

Leaky calcium channels in pancreatic beta cells can lead to high blood sugar

VIEW VIDEO

http://newsroom.cumc.columbia.edu/blog/2015/04/07/cellular-defect-linked-diabetes/?elq=c55ba8ff64104a0b8e2c82d78749fe88&elqCampaignId=9&elqaid=12507&elqat=1&elqTrackId=aefc67f3855b40fe8b0a4461f3b0ca74

“Pancreatic beta cells were found to have leaky RyR2s, which were disrupting the function of mitochondria that provide cells with energy required for insulin release. The dysfunction was consistent with mitochondrial alterations that have been described in pancreatic beta cells from patients with type 2 diabetes,” said Dr. Santulli.

See article

http://newsroom.cumc.columbia.edu/blog/2015/04/07/cellular-defect-linked-diabetes/?elq=c55ba8ff64104a0b8e2c82d78749fe88&elqCampaignId=9&elqaid=12507&elqat=1&elqTrackId=aefc67f3855b40fe8b0a4461f3b0ca74

 

pancreatic beta cells

Electron microscope image of a pancreatic beta cell, showing malformed mitochondria resulting from calcium leakage; the purple circle represents an insulin granule. (Credit: Dr. Gaetano Santulli)

 

About:

 

The paper is titled, “Calcium release channel RyR2 regulates insulin release and glucose homeostasis.”

The other contributors are: Gennaro Pagano (Imperial College, London, UK, University of Molise, Campobasso, Italy, and Federico II University, Naples, Italy), Celestino Sardu (Leiden University Medical Center, Leiden, Netherlands, Second University of Naples, Naples, Italy, and Catholic University of the Sacred Heart, John Paul II Foundation for Research and Treatment, Campobasso, Italy), Wenjun Xie (CUMC), Steven Reiken (CUMC), Salvatore Luca D’Ascia (Department of Cardiology and Arrhythmology, Clinical Institute Città Studi Hospital, Milan, Italy), Michele Cannone (Giuseppe Tatarella Hospital, Cerignola, Foggia, Italy), Nicola Marziliano (Niguarda Ca’ Granda Hospital, Milan, Italy, and University Hospital of Parma, Parma, Italy), Bruno Trimarco (Federico II University), Theresa A. Guise (Indiana University School of Medicine, Indianapolis, Indiana), and Alain Lacampagne (14U1046 INSERM, UMR 9214, CNRS, CHRU Montpellier, Montpellier, France)

The study was funded by grants from the American Heart Association (13POST16810041), the Schaefer Foundation, the Phillip Foundation, and the National Institutes of Health (R01HL061503, R01HL102040, and R01AR060037).

Dr. Marks is a consultant and board member of ARMGO Pharma, Inc., which is targeting RyR channels for therapeutic purposes. The other authors declare no financial or other conflicts of interest.

Columbia University Medical Center provides international leadership in basic, preclinical, and clinical research; medical and health sciences education; and patient care. The medical center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the College of Physicians and Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. Columbia University Medical Center is home to the largest medical research enterprise in New York City and State and one of the largest faculty medical practices in the Northeast. For more information, visit cumc.columbia.edu or columbiadoctors.org.

 

Other related articles on the role of Calcium in Health and in Disease were published in this Open Access Online Scientific Journal, include the following: 

 

Identification of Biomarkers that are Related to the Actin Cytoskeleton – Part I

Larry H Bernstein, MD, FCAP

 

Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility – Part II

Larry H. Bernstein, MD, FCAP, Stephen Williams, PhD and Aviva Lev-Ari, PhD, RN

 

Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease – Part III

Larry H. Bernstein, MD, FCAP, Stephen J. Williams, PhD
 and Aviva Lev-Ari, PhD, RN

 

The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets – Part IV

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

 

Ca2+-Stimulated Exocytosis:  The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter – Part V

Larry H Bernstein, MD, FCAP
and
Aviva Lev-Ari, PhD, RN

 

Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD – Part VI

Aviva Lev-Ari, PhD, RN

 

Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure – Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses – Part VII

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Disruption of Calcium Homeostasis: Cardiomyocytes and Vascular Smooth Muscle Cells: The Cardiac and Cardiovascular Calcium Signaling Mechanism – Part VIII

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Calcium-Channel Blockers, Calcium Release-related Contractile Dysfunction (Ryanopathy) and Calcium as Neurotransmitter Sensor – Part IX

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of vesicles with cell membranes during Neurotransmission – Part X

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

Sensors and Signaling in Oxidative Stress – Part XI

Larry H. Bernstein, MD, FCAP

 

Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD)) – Part XII

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

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Medical Headline Misinformation Strikes Again: Claims About Vitamin D

Reporter: Stephen J. Williams, Ph.D.

A recent posting by a group called the Vitamin D Council (and put on this site) had referred to, and misquoted, the Mayo Clinic site on the role of vitamin D on various diseases. At first I was curious if this was actually reported on the Mayo site on claims of prevention of various cancers (as results from retrospective studies had been conflicting) and originally had made some strong comments. From comments made from this post I do agree that there is strong evidence about vitamin D supplementation for the prevention of rickets but as Mayo reviewed claims about vitamin D supplementation and prevention of certain diseases such as cancers and heart disease may not be as strong as some suggest.  My main concern was : is the clinical evidence strong enough for the role of vitamin D supplementation in a wide array of diseases and did Mayo make the claims as suggested in some media reports?  Actually Mayo does a very thorough job of determining the clinical evidence and the focus of vitamins and cancer risk will be a point of further discussion.

After consulting the Mayo clinic website it appears that the Vitamin D Council site had indeed misquoted and misrepresented the medical information contained within the Mayo Clinic website.

Medical Misinformation Is Probably The Most Hazardous and Biggest Risk Impacting a Healthy Lifestyle

The site had made numerous claims on role of vitamin D3 (cholecalciferol) in numerous diseases; making it appear there were definitive links between low vitamin D3 and risk of hypertension, cancer, depression and diabetes.

A little background on Vitamin D

From Wikipedia

Vitamin D refers to a group of fat-soluble secosteroids responsible for enhancing intestinal absorption of calcium, iron, magnesium, phosphate and zinc. In humans, the most important compounds in this group are vitamin D3 (also known as cholecalciferol) and vitamin D2 (ergocalciferol).[1] Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements.[1][2][3] Very few foods contain vitamin D; synthesis of vitamin D (specifically cholecalciferol) in the skin is the major natural sources of the vitamin. Dermal synthesis of vitamin D from cholesterol is dependent on sun exposure (specifically UVB radiation).Vitamin D has a significant role in calcium homeostasis and metabolism. Its discovery was due to effort to find the dietary substance lacking in rickets (the childhood form of osteomalacia).[4]

also from Widipedia on Vitamin D toxicity

Vitamin D toxicity

Vitamin D toxicity is rare.[20] It is caused by supplementing with high doses of vitamin D rather than sunlight. The threshold for vitamin D toxicity has not been established; however, the tolerable upper intake level (UL), according to some research, is 4,000 IU/day for ages 9–71.[7] Whereas another research concludes that in healthy adults, sustained intake of more than 1250 μg/day (50,000 IU) can produce overt toxicity after several months and can increase serum 25-hydroxyvitamin D levels to 150 ng/ml and greater;[20][56] those with certain medical conditions, such as primary hyperparathyroidism,[57] are far more sensitive to vitamin D and develop hypercalcemia in response to any increase in vitamin D nutrition, while maternal hypercalcemia during pregnancy may increase fetal sensitivity to effects of vitamin D and lead to a syndrome of mental retardation and facial deformities.[57][58]

After being commissioned by the Canadian and American governments, the Institute of Medicine (IOM) as of 30 November 2010, has increased the tolerable upper limit (UL) to 2,500 IU per day for ages 1–3 years, 3,000 IU per day for ages 4–8 years and 4,000 IU per day for ages 9–71+ years (including pregnant or lactating women).[7]

Published cases of toxicity involving hypercalcemia in which the vitamin D dose and the 25-hydroxy-vitamin D levels are known all involve an intake of ≥40,000 IU (1,000 μg) per day.[57] Recommending supplementation, when those supposedly in need of it are labeled healthy, has proved contentious, and doubt exists concerning long-term effects of attaining and maintaining high serum 25(OH)D by supplementation.[61]

From the Mayo Clinic Website on Vitamin D

The Mayo Clinic has done a wonderful job curating the uses and proposed uses of vitamin D for various diseases and rates the evidence using a grading system A-F (as shown below):

Key to grades

A STRONG scientific evidence FOR THIS USE

B GOOD scientific evidence FOR THIS USE

C UNCLEAR scientific evidence for this use

D Fair scientific evidence AGAINST THIS USE (it may not work)

F Strong scientific evidence AGAINST THIS USE (it likely does not work)

Mayo has information for other natural products as well. As described below (and on the Mayo site here) most of the supposed evidence fails their criteria for a strong clinical link between diseases such as heart disease, hypertension, cancer and vitamin D (either parental or D3) levels.

The important take-home from the Mayo site is that there is strong evidence for the use of vitamin D in diseases related to the known mechanism of vitamin D such as low serum phosphate either due to kidney disease (Fanconi syndrome) or familial hypophosphatemia or in diseases surrounding bone metabolism like osteomalacia, rickets, dental cavities and even as a treatment for psoriasis or underactive parathyroid.

However most indications like hypertension, stroke, cancer prevention or treatment (other than supportive therapy for low vitamin D levels) get a poor grade (C or D) for clinical correlation from Mayo Clinic.

A Post in the Near Future will be a Curation of Validated Clinical Studies on Effects of Vitamins on Cancer Risk.

Below is taken from the Mayo Site:

Evidence

These uses have been tested in humans or animals.  Safety and effectiveness have not always been proven.  Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Grading rationale

Evidence grade Condition to which grade level applies
A

Deficiency (phosphate)

Familial hypophosphatemia is a rare, inherited condition in which there are low blood levels of phosphate and problems with vitamin D metabolism. It is a form of rickets. Taking calcitriol or dihydrotachysterol by mouth along with phosphate supplements is effective for treating bone disorders in people with this disease. Those with this disorder should be monitored by a medical professional.

A

Kidney disease (causing low phosphate levels)

Fanconi syndrome is a kidney disease in which nutrients, including phosphate, are lost in the urine instead of being reabsorbed by the body. Taking ergocalciferol by mouth is effective for treating low phosphate levels caused by Fanconi syndrome.

A

Osteomalacia (bone softening in adults)

Adults who have severe vitamin D deficiency may experience bone pain and softness, as well as muscle weakness. Osteomalacia may be found among the following people: those who are elderly and have diets low in vitamin D; those with problems absorbing vitamin D; those without enough sun exposure; those who undergo stomach or intestine surgery; those with bone disease caused by aluminum; those with chronic liver disease; or those with bone disease associated with kidney problems. Treatment for osteomalacia depends on the cause of the disease and often includes pain control and surgery, as well as vitamin D and phosphate-binding agents.

A

Psoriasis (disorder causing skin redness and irritation)

Many different approaches are used to treat psoriasis, including light therapy, stress reduction, moisturizers, or salicylic acid. For more severe cases, calcipotriene (Dovonex®), a man-made substance similar to vitamin D3, may help control skin cell growth. This agent is a first-line treatment for mild-to-moderate psoriasis. Calcipotriene is also available with betamethasone and may be safe for up to one year. Vitamin D3 (tacalcitol) ointment or high doses of becocalcidiol applied to the skin are also thought to be safe and well-tolerated.

A

Rickets (bone weakening in children)

Rickets may develop in children who have vitamin D deficiency caused by a diet low in vitamin D, a lack of sunlight, or both. Babies fed only breast milk (without supplemental vitamin D) may also develop rickets. Ergocalciferol or cholecalciferol is effective for treating rickets caused by vitamin D deficiency. Calcitriol should be used in those with kidney failure. Treatment should be under medical supervision.

A

Thyroid conditions (causing low calcium levels)

Low levels of parathyroid hormone may occur after surgery to remove the parathyroid glands. Taking high doses of dihydrotachysterol, calcitriol, or ergocalciferol by mouth, with or without calcium, may help increase calcium levels in people with this type of thyroid problem. Increasing calcium intake, with or without vitamin D, may reduce the risk of underactive parathyroid glands.

A

Thyroid conditions (due to low vitamin D levels)

Some people may have overactive parathyroid glands due to low levels of vitamin D, and vitamin D is the first treatment for this disorder. For people who have overactive parathyroid glands due to other causes, surgery to remove the glands is often recommended. Studies suggest that vitamin D may help reduce the risk of further thyroid problems after undergoing partial or total removal of the parathyroid glands.

A

Vitamin D deficiency

Vitamin D deficiency is associated with many conditions, including bone loss, kidney disease, lung disorders, diabetes, stomach and intestine problems, and heart disease. Vitamin D supplementation has been found to help prevent or treat vitamin D deficiency.

B

Dental cavities

Much evidence has shown that vitamin D helps prevent cavities; however, more high-quality research is needed to further support this finding.

B

Renal osteodystrophy (bone problems due to chronic kidney failure)

Renal osteodystrophy refers to the bone problems that occur in people with chronic kidney failure. Calcifediol or ergocalciferol taken by mouth may help prevent this condition in people with chronic kidney failure who are undergoing treatment.

C

Autoimmune diseases

Vitamin D may reduce inflammation and help prevent autoimmune diseases, including rheumatoid arthritis, multiple sclerosis, and Crohn’s disease. However, further high-quality research is needed to confirm these results.

C

Bone density (children)

Vitamin D improves bone density in children who are vitamin D deficient. However, results are unclear and more research is needed.

C

Bone diseases (kidney disease or kidney transplant)

Vitamin D has been studied for people with chronic kidney disease. The use of substances similar to vitamin D has been found to increase bone density in people with kidney disease. The effect of vitamin D itself is unclear. Further research is needed before conclusions can be made.

C

Cancer prevention (breast, colorectal, prostate, other)

Many studies have looked at the effects of vitamin D on cancer. Positive results have been reported with the use of vitamin D alone or with calcium. Vitamin D intake with or without calcium has been studied for colorectal, cervical, breast, and prostate cancer. A reduced risk of colorectal cancer has been shown with vitamin D supplementation. However, there is a lack of consistent or strong evidence. Further study is needed.

C

Fibromyalgia (long-term, body-wide pain)

Vitamin D has been studied for the treatment of fibromyalgia, but evidence is lacking in support of its effectiveness. Further study is needed.

C

Fractures (prevention)

Conflicting results have been found on the use of vitamin D for fracture prevention. The combination of alfacalcidol and alendronate has been found to reduce the risk of falls and fractures. However, further high-quality research is needed before firm conclusions can be made.

C

Hepatic osteodystrophy (bone disease in people with liver disease)

Metabolic bone disease is common among people with chronic liver disease, and osteoporosis accounts for the majority of cases. Varying degrees of poor calcium absorption may occur in people with chronic liver disease due to malnutrition and vitamin D deficiency. Vitamin D taken by mouth or injected may play a role in the management of this condition.

C

High blood pressure

Low levels of vitamin D may be linked to high blood pressure. Blood pressure is often higher during the winter season, at a further distance from the equator, and in people with dark skin pigmentation. However, the evidence is unclear. More research is needed in this area. People who have high blood pressure should be managed by a medical professional.

C

Immune function

Early research suggests that vitamin D and similar compounds, such as alfacalcidol, may impact immune function. Vitamin D added to standard therapy may benefit people with infectious disease. More studies are needed to confirm these results.

C

Seasonal affective disorder (SAD)

SAD is a form of depression that occurs during the winter months, possibly due to reduced exposure to sunlight. In one study, vitamin D was found to be better than light therapy in the treatment of SAD. Further studies are necessary to confirm these findings.

C

Stroke

Higher levels of vitamin D may decrease the risk of stroke. However, further study is needed to confirm the use of vitamin D for this condition.

C

Type 1 diabetes

Some studies suggest that vitamin D may help prevent the development of type 1 diabetes. However, there is a lack of strong evidence to support this finding.

C

Type 2 diabetes

Vitamin D has mixed effects on blood sugar and insulin sensitivity. It is often studied in combination with calcium. Further research is needed to confirm these results.

D

Cancer treatment (prostate)

Evidence suggests a lack of effect of vitamin D as a part of cancer treatment for prostate cancer. Further study is needed using other formulations of vitamin D and other types of cancer.

D

Heart disease

Vitamin D is recognized as being important for heart health. Overall, research is not consistent, and some studies have found negative effects of vitamin D on heart health. More high-quality research is needed to make a firm conclusion.

D

High cholesterol

Many studies have looked at the effects of vitamin D alone or in combination with other agents for high cholesterol, but results are inconsistent. Some negative effects have been reported. More research is needed on the use of vitamin D alone or in combination with calcium.

Other related articles on Vitamins and Disease were published in this Open Access Online Scientific Journal, include the following:

Multivitamins – Don’t help Extend Life or ward off Heart Disease and Improve state of Memory Loss

Diet and Diabetes

What do you know about Plants and Neutraceuticals?

Malnutrition in India, high newborn death rate and stunting of children age under five years

Omega-3 fatty acids, depleting the source, and protein insufficiency in renal disease

American Diet is LOW in four important Nutrients that have a direct bearing on Aging and the Brain

Parathyroids and Bone Metabolism

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Parathyroids and Bone Metabolism

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

 

 

Parathyroid hormone (PTH), parathormone or parathyrin, is secreted by the chief cells of the parathyroid glands as a polypeptide containing 84 amino acids. It acts to increase the concentration of calcium (Ca2+) in the blood, whereas calcitonin (a hormone produced by the parafollicular cells (C cells) of the thyroid gland) acts to decrease calcium concentration. PTH acts to increase the concentration of calcium in the blood by acting upon the parathyroid hormone 1 receptor (high levels in bone and kidney) and the parathyroid hormone 2 receptor (high levels in the central nervous system, pancreas, testis, and placenta). PTH half-life is approximately 4 minutes.[2] It has a molecular mass of 9.4 kDa.

hPTH-(1-34) crystallizes as a slightly bent, long helical dimer. Analysis reveals that the extended helical conformation of hPTH-(1-34) is the likely bioactive conformation.[4] The N-terminal fragment 1-34 of parathyroid hormone (PTH) has been crystallized and the structure has been refined to 0.9 Å resolution.

The_ribbon_cartoon_structure - hPTH helical dimer

The_ribbon_cartoon_structure – hPTH helical dimer

http://upload.wikimedia.org/wikipedia/commons/1/1e/The_ribbon_cartoon_structure.png

Regulation of serum calcium

PTH was one of the first hormones to be shown to use the G-protein, adenylyl cyclase second messenger system.

Normal total plasma calcium level ranges from 8.5 to 10.2 mg/dL (2.12 mmol/L to 2.55 mmol/L).

Region Effect
bone It enhances the release of calcium from the large reservoir contained in the bones.[7] Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH. Stimulation is indirect since osteoclasts do not have a receptor for PTH; rather, PTH binds to osteoblasts, the cells responsible for creating bone. Binding stimulates osteoblasts to increase their expression of RANKL and inhibits their expression of Osteoprotegerin (OPG). OPG binds to RANKL and blocks it from interacting with RANK, a receptor for RANKL. The binding of RANKL to RANK (facilitated by the decreased amount of OPG available for binding the excess RANKL) stimulates these osteoclast precursors to fuse, forming new osteoclasts, which ultimately enhances bone resorption
kidney It enhances active reabsorption of calcium and magnesium from distal tubules and the thick ascending limb. As bone is degraded, both calcium and phosphate are released. It also decreases the reabsorption of phosphate, with a net loss in plasma phosphate concentration. When the calcium:phosphate ratio increases, more calcium is free in the circulation
intestine via kidney It enhances the absorption of calcium in the intestine by increasing the production of activated vitamin D. Vitamin D activation occurs in the kidney. PTH up-regulates25-hydroxyvitamin D3 1-alpha-hydroxylase, the enzyme responsible for 1-alpha hydroxylation of 25-hydroxy vitamin D, converting vitamin D to its active form (1,25-dihydroxy vitamin D). This activated form of vitamin D increases the absorption of calcium (as Ca2+ ions) by the intestine via calbindin.

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

Development of Present Concepts of the Parathyroid –
The Parathyroids – Progress, problems and practice,
in Current Problems in Surgery, 1971; 8(8): 3-64.
Leon Goldman, Gilbert Gordon, Betty S. Roof
http://dx.doi.org/10.1016/S0011-3840(71)80008-4

The parathyroid gland first achieved clinical significance because of hypoparathyroid tetany. Tetany: a syndrome manifested by painful muscle spasms or rigors; is derived from the Greek:  tetanos, past participle of the verb teinein, meaning “to stretch,” Tetany : stretched, or spastic, in modern terms “up tight.,’ When the word was used by Hippocrates, no differentiation was made between the types of muscular spasms caused by neurotoxins (e.g., lockjaw) and those of metabolic causes. The word ~ went through the Latin, tetanus, and to French. Te’tanie, where the attribute of intermittent muscular spasm was added.

Owea's drawing of parathyroid gland of Indian rhinoceros

Owea’s drawing of parathyroid gland of Indian rhinoceros

Owea’s drawing of parathyroid gland of Indian rhinoceros

According to file Oxford English Dictionary, the relation of tetany to surgical operations was noted in tile year 1805 in The Medical Journal XIV, 304: “tetanie affections very often to|low the great operations. . .” It is not clear from this reference what type of operations were invo]ved.  The relationship of tetany to thyroidectomy was recognized as early as 1878 when WoIfler described convulsions in one of the patients on whom Billroth had performed a total thyroidectomy. The great surgeon WilIiam Stewart Halsted suggested that postoperative hypoparathyroidism had not been reported earlier because before that time total thyroidectomy had always been fatal, leaving insufficient time for tetany to develop. In 1883 Weiss collected 13 cases of tetany, all following total thyroidcctomy. The relation to total thyroidectomy became historically significant later when postoperative tetany was misinterpreted as the acute form of thyroid insufficiency, while myxedema was correctly recognized as the chronic form.
Anatomically, the parathyroid glands had been noted fleetingly by Remak (1855), by Virchow (1863) and probably by others in the course of human dissection. Perhaps better publicized was the description by Sir Richard Owen, published in 1852. As Hunterian Professor and Conservator of the Museum in the Royal College of Surgeons, Owen anatomized animals that died at the London Zoo. In 1849, while performing an autopsy on tile Great Indian rhinoceros, Owen clearly noted, drew and named the parathyroid gland (Fig. 1). However, microscopic examination was not reported, and it was not known at that time whether the parathyroid gland was separate.
The causal relationship of the parathyroid gland to post-thyroidectomy tetany was clarified by the French physiologist Eugdne Gley in 1891. He showed that, in the rabbit, removal of the thyroid gland was not responsible for these seizures but that removal of the parathyroid glands caused fatal convulsions.
Very soon after this, a parallel discovery was made in Berkeley, California, by Jacques Loeb.  Loeb noticed that the rhythmic contractions of a frog muscle in a saline medium were stopped by the addition of calcium. He concluded that calcium has the important function of inhibiting excessive neuromuscular
irritability.  Loeb’s studies led MacCallum, in 1909, to investigate the possibility that a low blood calcium level might be responsible for the increased excitability of the muscles, in hypoparathyroid tetany.  He and Voegtlin removed the parathyroids from dogs and showed that tetany ensued when the serum calcium level fell. They also showed that administration of calcium promptly relieved tetany. Less well known is their publication in the following
year, which entirely recanted the earlier view. Their observations that calcium, magnesium and strontium immediately abolish tetany, and the report of Joseph and Sleltzer that infusion of hypertonic sodium chloride slowly relieves this kind of tetany, led MacCallum to believe that the effect of calcium was nonspecific.
By this time thyroid surgery was being performed widely. The Reverdin brothers in Geneva noted what they considered complex nervous manifestations following total thyroidectomv, Moussu’ s observations in animals were confirmed in patients; post-thyroidectomy convulsions were not necessarily fatal.
Thyroid surgery was now sufficiently improved so that Kocher was able to find symptoms of tetany–and these were transient ….. in only 1 of his 18 cases of total thyroidectomy. How many more would have been identified as victims of hypoparathyroidism by appropriate chemical examination can only be conjectured. By 1907 Halsted had recognized the importance of the parathyroids and how essential the intimate knowledge of their anatomy is to the goiter surgeon. Halsted put a bright young medical student to work on this project as a penalty for delinquent attendance at lectures. The sketch of the beautiful dissection by the student, Herbert McLean Evans, was used by Halsted to illustrate his monograph on The Operative History of Goiter. On the basis of this knowledge, of anatomy, it was established that the parathyroids are usually related to the posterior capsule and that leaving this capsule intact greatly reduces the risk of tetany.
In 1923 the distinguished Norwegian physician-physiologist, Harald Salvesen published beautiful, imaginative and thorough studies in which he showed, that complete parathyroid ablation invariably lowered the blood calcium, that the blood sugar level was not altered and that guanidine accumulation occurred only terminally during agonal convulsions. He further found that parathyroid tetany could be prevented by calcium feeding and confirmed MacCallum’s earlier observation that it could be promptly corrected by calcium infusion. He also noted that one of his dogs with parathyroid tetany developed a cataract. In our opinion, the relation of the parathyroid gland to calcium metabolism was first firmly established by Salvesen in 1923.
Consider the knowledge and use of endocrines in 1923. Desiccated thyroid, which Osler had praised as the miracle of modern metabolic therapy, was the only orally effective endocrine preparation. ]nsulin had just been discovered. Another potent preparation was the hydrochloric acid extract of parathyroid glands made by Adolph Hanson. That it was an effective preparation is perhaps best attested by the fact that it is still used, under the name Parathyroid Extract USP, and that much of the work on the actions of parathyroid hormone has been carried out with this crude extract. In 1925 Collip, who had been of such immeasurable help to Banting, Best and McLeod in preparing a clean, potent insulin extract from normal pancreas, applied his genius to the parathyroid with an equally satisfactory result. His relatively clean parathyroid extract  made it possible for the first time to elucidate the actions of the parathyroid glands in man.
Using this preparation, Albright and Ellsworth in 1929 clarified the two fundamental actions of parathyroid hormone (PTH) identical with those obtained nowadays with the most highly purified preparations. These two actions are:
(1) elevation of serum calcium and
(2) excretion of phosphate by the kidneys, with a consequent lowering of the serum phosphate.
It will later be shown that the action that raises serum calcium levels is, for the most part, an increase in the rate of bone breakdown. It remained for Copp and associates to show in 1961 that another horrnone, calcitonin, with an opposite action, is necessary for maintenance of calcium homeostasis. And still later Chase and Aurbach showed in 1968 that the phosphaturic action of PTH is mediated by the enzyme adenyl cyclase, which stimulates production of cyclic 3’5′-adenosine monophosphate (AMP).
It is now clear that hypophosphatemia predisposes to hyperealcemia and that hyperphosphatemia can actually abolish hypercalcemia. However, numerous experiments, one of them by Albright’s collaborators, Ellsworth and Futeher in 1935 showed that parathyroid extract raised the serum calcium level in the absence of the kidneys.  Clearly, therefore, the calcium-mobilizing effect of PTH is not the result of the phosphate diuretic action only. Conclusive evidence was obtained by Barnicot of Cambridge in 1948. …
The brilliant group at the Massachusetts General Hospital, led by Aub and including two young men destined to make brilliant records in American medicine Fuller Albright and Waiter Bauer soon showed that the kind of hyperparathyroidism described by Recklinghausen, Mandl and Askanazy is, in fact, the end stage of a series of chemical events predictable from the known actions of PTH. Starting with the famous case of Captain Charles Martell, a mariner with severe bone disease, who shrank in stature in 10 years, Albright soon clarified the most significant feature of hyperparathyroidism: the hypercalcemia that is found in at least 99% of patients with proved primary hyperparathyroidism.
It was not until 1953 that Jonas Shota directly demonstrated the other action of excess PTH in hyperparathyroidism: a low rate of tubular reabsorption of phosphate (TRP), as fifteen years later, in 1968, Chase and Aurbach would show that this action is mediated by renal adenyl cyclase and cyclic AMP. Meanwhile, in 1935, Pappenheimer and Wilens had described another form of hyperparathyroidism arising not as a primary tumor, but as a secondary or compensatory response to the metabolic abnormalities of uremia. Goldman independently described this phenomenon. It .is noteworthy that hyperparathyroidism secondary to lack of dietary calcium had already been described by Erdheiqm and that  these 2 causes of secondary hyperparathyroidism, Uremia and intestinal malabsorption, have subsequently been shown, to have in comrnon inadequate intestinal absorption of calcium.
Since the classic studies of Sandstrom, Gley, Loeb, Salvesen, Cotlip, Aub, Bauer and Albright, enormous strides have advanced our knowledge of parathyroid physiology. Isolation, purification, and characterization of  the hormone and development of a highly sensitive  radioimmunoassay for PTH.  Almost slmultaneously in1959, Aurbach, Rasmussen and Craig obtained a purified bovine PTH. These two groups of investigators identified a similar peptide with a molecular weight of about 8,500 and with biological activity of about 3.000 units/mg. This peptide contains 84 amino acid residfies the first 30-45 are necessary for biologic and immunologic activity. A tentative molecular structure reported by Potts, Aurbach and Sherwood in 1965 has subsequently been modified by Brewer and Ronan, with confirmation by Niall et aI. in Potts’s laboratory. The heterogeneous  nature of circulating PTH was first: shown by Berson and Yalow using two antisera prepared from beef PTH but showing quantitative differences in reaction to circulating PTH. They were able  to detect two parathormones, one with a half-life of only 10-20 minutes, and another with a half-life of about 1.5 hours.
The parathyroid hormone-regulated transcriptome in osteocytes: Parallel actions with 1,25-dihydroxyvitamin D3 to oppose gene expression changes during differentiation and to promote mature cell function

Hillary C. St. John, MB Meyer, NA Benkusky, AH Carlson, M Prideaux, et al.
Bone 72 (2015) 81–91
http://dx.doi.org/10.1016/j.bone.2014.11.010

Although localized to the mineralized matrix of bone, osteocytes are able to respond to systemic factors such as the calciotropic hormones 1, 25-(OH)2 D3 and PTH. In the present studies, we examined the transcriptomic response to PTH in an osteocyte cell model and found that this hormone regulated an extensive panel of genes. Surprisingly, PTH uniquely modulated two cohorts of genes, one that was expressed and associated with the osteoblast to osteocyte transition and the other a cohort that was expressed only in the mature osteocyte. Interestingly, PTH’s effects were largely to oppose the expression of differentiation-related genes in the former cohort, while potentiating the expression of osteocyte-specific genes in the latter cohort. A comparison of the transcriptional effects of PTH with those obtained previously with 1, 25-(OH)2 D3 revealed a subset of genes that was strongly overlapping. While 1, 25-(OH)2 D3 potentiated the expression of osteocyte-specific genes similar to that seen with PTH, the overlap between the two hormones was more limited. Additional experiments identified the PKA-activated phospho-CREB (pCREB) cistrome, revealing that while many of the differentiation-related PTH regulated genes were apparent targets of a PKA-mediated signaling pathway, a reduction in pCREB binding at sites associated with osteocyte-specific PTH targets appeared to involve alternative PTH activation pathways. That pCREB binding activities positioned near important hormone-regulated gene cohorts were localized to control regions of genes was reinforced by the presence of epigenetic enhancer signatures exemplified by unique modifications at histones H3 and H4. These studies suggest that both PTH and 1, 25-(OH)2 D3 may play important and perhaps cooperative roles in limiting osteocyte differentiation from its precursors while simultaneously exerting distinct roles in regulating mature osteocyte function. Our results provide new insight into transcription factor-associated mechanisms through which PTH and 1, 25-(OH)2 D3 regulate a plethora of genes important to the osteoblast/osteocyte lineage.

Bone, a dynamic and integrating tissue

The guest editors Bram C.J. van der Eerden, Anna Teti, Willian F. Zambuzzi
Archives of Biochemistry and Biophysics 561 (2014) 1–2
http://dx.doi.org/10.1016/j.abb.2014.08.012

The special issue ‘Bone, a dynamic and integrating tissue’ provides the most recent information regarding the interacting nature of bone cells with their immediate neighboring cells within the skeleton as well as with distant target cells in other organs, using different types of both cellular and non-cellular communication. It should appeal to any scientist or clinician in the field, given the wide variety of topics, covering molecular, experimental cell and animal biology, biomechanics and -physics, genetics and medicine.

This special issue arose from a collaboration between the guest editors within ‘INTERBONE’, a European Union funded Marie Curie Actions – People – International Research Staff Scheme (PIRSESGA-2011-295181) on the interplay among bone cells, matrices and systems.

Over the recent years, many developments have paved new avenues to study signaling pathways and mechanisms in bone in much greater detail. Genetic progress has been made, which has provided us with novel genes behind already known as well as hitherto idiopathic bone diseases. The enormous expansion of specific animal models has enabled us to study new mechanisms and pathways in vivo in great spatial and temporal detail. As a consequence, novel treatment modalities have seen the light, which are predominantly focusing on bone anabolic therapies. These advances will not cease to exist and an exciting biological era lies ahead of us, with many discoveries to be made.

In this special issue of Archives in Biochemistry and Biophysics, experts in the field of bone metabolism have addressed the recent developments in which special attention is paid to the concept that bone is not just a static, isolated organ, but a dynamic and integrating tissue. Over the last decade, discoveries have led to the notion that bone cells are interacting with many other cell types within bone. Besides this intraskeletal communication, bone cells produce factors that are capable of controlling cell types and organs elsewhere in the organism, which are now being recognized as bona fide hormones.

All contributors have explored the recent advances made in their research area. The latest progress in osteoblast/osteocyte and osteoclast biology is revisited with special focus on bone morphogenetic proteins, microRNAs and extracellular vesicles as illustrative examples of different levels of communication between cell types. In separate chapters, the interaction of osteoblasts and osteoclasts, as well as their cross-talk with endothelial cells, fat cells, immune cells, hematopoietic stem cells and different types of cancer cells is discussed extensively, further emphasizing the interactive nature of bone cells in their microenvironment. Beside cell–cell interaction, attention has been paid to the osteointegration of bone cells in a non-cellular context, including extracellular matrix and metal devices, combining main components for bone bioengineering. Finally, the endocrine role of bone is discussed in great detail by several contributors, focusing on the control of bone cell function by the brain as well as the role of bone-produced factors in, amongst others, phosphate homeostasis, energy metabolism and fertility.

The Great Beauty of the osteoclast

Alfredo Cappariello, Antonio Maurizi, Vimal Veeriah, Anna Teti
Archives of Biochemistry and Biophysics 561 (2014) 13–21
http://dx.doi.org/10.1016/j.abb.2014.08.009

Much has been written recently on osteoclast biology, but this cell type still astonishes scientists with its multifaceted functions and unique properties. The last three decades have seen a change in thinking about the osteoclast, from a cell with a single function, which just destroys the tissue it belongs to, to an ‘‘orchestrator’’ implicated in the concerted regulation of bone turnover. Osteoclasts have unique morphological features, organelle distribution and plasma membrane domain organization. They require polarization to cause extracellular bone breakdown and release of the digested bone matrix products into the circulation. Osteoclasts contribute to the control of skeletal growth and renewal. Alongside other organs, including kidney, gut, thyroid and parathyroid glands, they also affect calcemia and phosphatemia. Osteoclasts are very sensitive to pro-inflammatory stimuli, and studies in the ‘00s ascertained their tight link with the immune system, bringing about the question why bone needs a cell regulated by the immune system to remove the extracellular matrix components. Recently, osteoclasts have been demonstrated to contribute to the hematopoietic stem cell niche, controlling local calcium concentration and regulating the turnover of factors essential for hematopoietic stem cell mobilization. Finally, osteoclasts are important regulators of osteoblast activity and angiogenesis, both by releasing factors stored in the bone matrix, and secreting ‘‘clastokines’’ that regulate the activity of neighboring cells. All these facets will be discussed in this review article, with the aim of underscoring The Great Beauty of the osteoclast.

Osteoclasts: more than ‘bone eaters’

Julia F. Charles and Antonios O. Aliprantis
Trends in Molecular Medicine, Aug 2014; 20(8): 449-459
http://dx.doi.org/10.1016/j.molmed.2014.06.001

As the only cells definitively shown to degrade bone, osteoclasts are key mediators of skeletal diseases including osteoporosis. Bone-forming osteoblasts, and hematopoietic and immune system cells, each influence osteoclast formation and function, but the reciprocal impact of osteoclasts on these cells is less well appreciated. We highlight here the functions that osteoclasts perform beyond bone resorption.
First, we consider how osteoclast signals may contribute to bone formation by osteoblasts and to the pathology of bone lesions such as fibrous dysplasia and giant cell tumors.
Second, we review the interaction of osteoclasts with the hematopoietic system, including the stem cell niche and adaptive immune cells. Connections between osteoclasts and other cells in the bone microenvironment are discussed within a clinically relevant framework.

Bone is a composite tissue of protein and mineral which undergoes continual remodeling to grow, heal damage, and regulate calcium and phosphate metabolism. This remodeling process is executed by the concerted and sequential effort of bone-resorbing osteoclasts and bone-forming osteoblasts, acting in what has been termed the basic multicellular unit (BMU) (Figure 1A). Osteocytes, long-lived osteoblast-derived cells that reside within the bone matrix, monitor bone quality and stress, and coordinate remodeling through membrane-bound and secreted factors. Skeletal integrity is maintained throughout the life-span by matching bone formation and resorption, a process referred to as osteoclast:osteoblast  ‘coupling.’ Coupling is thoroughly summarized in recent excellent reviews and in Figure 1.

Coupling: how osteoclasts ‘talk back’ to cells of the osteoblast lineage Coupling of bone formation to resorption is likely achieved through multiple mechanisms, including signals that stimulate the proliferation of pre-osteoblasts, their recruitment to resorption lacunae, and their differentiation into bone-forming cells. Cellular mediators of coupling include osteoclasts, osteoblasts, osteocytes, macrophages, and T cells, which produce a variety of factors including Wnt pathway regulators, such as sclerostin, and cytokines such as oncostatin M

Osteoclasts–osteoblast interactions in the basic multicellular unit (BMU).

Osteoclasts–osteoblast interactions in the basic multicellular unit (BMU).

Osteoclasts–osteoblast interactions in the basic multicellular unit (BMU).
Cell–cell contact mechanisms may also mediate OC-OB communication. Bidirectional signaling from OC ephrins and OB Eph receptors, and reverse signaling through RANKL on OBs, have both been invoked.

Box 1. Usurping local resources: osteoclasts feed bone invaders

Liberation of growth factors embedded in bone matrix by osteoclasts may promote metastatic tumor growth in bone. Reciprocal stimulation of osteoclasts by cancer cell derived parathyroid hormone related protein (PTHrP), and other factors, could potentiate growth factor release in what has been termed the ‘vicious cycle’ ]. Xenograft experiments utilizing breast cancer cells expressing a TGFβ responsive reporter demonstrated osteolytic metastases had high TGFβ activity. Inhibition of osteoclastic bone resorption with pamidronate reduced TGFβ activity and osteolytic lesions, suggesting that matrix resorption is a relevant source of TGFβ for skeletal metastasis in vivo. Although prophylactic pamidronate treatment decreased frequency of bone metastasis, the drug did not decrease disease progression if administered after tumor cell inoculation. Thus, whether inhibiting the release of matrix growth factors by osteoclasts has a substantive effect on tumor growth is unclear. Several bisphosphonates, as well as the anti-RANKL antibody denosumab, reduce skeletal events in metastatic cancer, but data on whether they prevent bone metastasis are inconsistent.

Immunoregulation by osteoclasts. Osteoclast precursors (OCPs) and osteoclasts (OCs) inhibit CD4 and CD8 T cell proliferation via nitric oxide (NO) production in response to T cell derived interferon g (IFNg). IFNg in turn inhibits differentiation of OCPs into mature OCs. OCs also present antigen through major histocompatibility complex class I (MHCI) to skew CD8+ T cells toward an induced Treg phenotype termed OC-iTcreg. OC-iTcreg cells in turn inhibit OCP differentiation to mature OC through IFNg, interleukin 10 (IL10), and IL6.

In mouse models, we suggest that systems for the temporal deletion of conditional alleles in osteoclasts and their precursors be established. Moreover, clinical research in humans with emerging therapeutics which specifically target key regulators of bone remodeling, such as RANKL, cathepsin K, and sclerostin, could include nested translational studies that specifically address their effects on the immune system, HSCs, and tumor growth, where appropriate. In these ways, a clear picture of osteoclast biology beyond their role as ‘bone eaters’ will emerge.

Leukemia inhibitory factor: A paracrine mediator of bone metabolism

Natalie A. Sims & Rachelle W. Johnson
Growth Factors, April 2012; 30(2): 76–87
http://dx.doi.org:/10.3109/08977194.2012.656760

Leukemia inhibitory factor (LIF) is a soluble interleukin-6 family cytokine that regulates a number of physiologic functions, including normal skeletal remodeling. LIF signals through the cytokine co-receptor glycoprotein-130 in complex with its cytokine-specific receptor [LIF receptor (LIFR)] to activate signaling cascades in cells of the skeletal system, including stromal cells, chondrocytes, osteoblasts, osteocytes, adipocytes, and synovial fibroblasts. LIF action on skeletal cells is cell-type specific, and frequently dependent on the state of cell differentiation. This review describes the expression patterns of LIF and LIFR in bone, their regulation by physiological and inflammatory agents, as well as cell-specific influences of LIF on osteoblast, osteoclast, chondrocyte, and adipocyte differentiation. The actions of LIF in normal skeletal growth and maintenance, in pathological states (e.g. autocrine tumor cell signaling and growth in bone) and inflammatory conditions (e.g. arthritis) will be discussed, as well as the signaling pathways activated by LIF and their importance in bone formation and resorption.

In vivo evidence of IGF-I–estrogen crosstalk in mediating the cortical bone response to mechanical strain

Subburaman Mohan, CG Bhat, JE Wergedal and C Kesavan
Bone Research (2014) 2, 14007 http://dx.doi.org:/10.1038/boneres.2014.7

Although insulin-like growth factor-I (IGF-I) and estrogen signaling pathways have been shown to be involved in mediating the bone anabolic response to mechanical loading, it is not known whether these two signaling pathways crosstalk with each other in producing a skeletal response to mechanical loading. To test this, at 5 weeks of age, partial ovariectomy (pOVX) or a sham operation was performed on heterozygous IGF-I conditional knockout (HIGF-I KO) and control mice generated using a Cre-loxP approach. At 10 weeks of age, a 10 N axial load was applied on the right tibia of these mice for a period of 2 weeks and the left tibia was used as an internal non-non-loaded control. At the cortical site, partial estrogen loss reduced total volumetric bone mineral density (BMD) by 5% in control pOVX mice (P50.05, one-way ANOVA), but not in the H IGF-I KO pOVX mice. At the trabecular site, bone volume/total volume (BV/TV) was reduced by 5%–6% in both control pOVX (P,0.05) and H IGF-I KO pOVX (P50.05) mice. Two weeks of mechanical loading caused a 7%–8% and an 11%–13%(P,0.05 vs. non-loaded bones) increase in cortical BMD and cortical thickness (Ct.Th), respectively, in the control sham, control pOVX and H IGF-I KO sham groups. By contrast, the magnitude of cortical BMD (4%, P50.13) and Ct.Th (6%, P,0.05) responses were reduced by 50% in the H IGF-I KO pOVX mice compared to the other three groups. The interaction between genotype and estrogen deficiency on the mechanical loading-induced cortical bone response was significant (P,0.05) by two-way ANOVA. Two weeks of axial loading caused similar increases in trabecular BV/TV (13%–17%) and thickness (17%–23%) in all four groups of mice. In conclusion, partial loss of both estrogen and IGF-I significantly reduced cortical but not the trabecular bone response to mechanical loading, providing in vivo evidence of the above crosstalk in mediating the bone response to loading.

Role of FGF/FGFR signaling in skeletal development and homeostasis: learning from mouse models

Nan Su, Min Jin and Lin Chen
Bone Research (2014) 2, 14003; http://dx.doi.org:/10.1038/boneres.2014.3

Fibroblast growth factor (FGF)/fibroblast growth factor receptor (FGFR) signaling plays essential roles in bone development and diseases. Missense mutations in FGFs and FGFRs in humans can cause various congenital bone diseases, including chondrodysplasia syndromes, craniosynostosis syndromes and syndromes with dysregulated phosphate metabolism. FGF/FGFR signaling is also an important pathway involved in the maintenance of adult bone homeostasis. Multiple kinds of mouse models, mimicking human skeleton diseases caused by missense mutations in FGFs and FGFRs, have been established by knock-in/out and transgenic technologies. These genetically modified mice provide good models for studying the role of FGF/FGFR signaling in skeleton development and homeostasis. In this review, we summarize the mouse models of FGF signaling-related skeleton diseases and recent progresses regarding the molecular mechanisms, underlying the role of FGFs/FGFRs in the regulation of bone development and homeostasis. This review also provides a perspective view on future works to explore the roles of FGF signaling in skeletal development and homeostasis.

Osteoporosis in men: a review

Robert A Adler
Bone Research (2014) 2, 14001; http://dx.doi.org:/10.1038/boneres.2014.1

Osteoporosis and consequent fracture are not limited to postmenopausal women. There is increasing attention being paid to osteoporosis in older men. Men suffer osteoporotic fractures about 10 years later in life than women, but life expectancy is increasing faster in men than women. Thus, men are living long enough to fracture, and when they do the consequences are greater than in women, with men having about twice the 1-year fatality rate after hip fracture, compared to women. Men at high risk for fracture include those men who have already had a fragility fracture, men on oral glucocorticoids or those men being treated for prostate cancer with androgen deprivation therapy. Beyond these high risk men, there are many other risk factors and secondary causes of osteoporosis in men. Evaluation includes careful history and physical examination to reveal potential secondary causes, including many medications, a short list of laboratory tests, and bone mineral density testing by dual energy X-ray absorptiometry (DXA) of spine and hip. Recently, international organizations have advocated a single normative database for interpreting DXA testing in men and women. The consequences of this change need to be determined. There are several choices of therapy for osteoporosis in men, with most fracture reduction estimation based on studies in women.

From skeletal to non skeletal: The intriguing roles of BMP-9: A literature review

  1. Leblanc, G. Drouin, G. Grenier, N. Faucheux, R. Hamdy
    Advances in Bioscience and Biotechnology, 2013; 4: 31-46
    http://dx.doi.org/10.4236/abb.2013.410A4004

In the well-known superfamily of transforming growth factors beta (TGF-), bone morphogenetic proteins (BMPs) are one of the most compelling cytokines for their major role in regulation of cell growth and differentiation in both embryonic and adult tissues. This subfamily was first described for its ability of potentiating bone formation, but nowadays, the power of BMPs is well beyond the bone healing scope. Some of the BMPs have been well studied and described in the literature, but the BMP9 is still worthy of attention. It has been shown by many authors that it is the most potent osteogenic BMP. Moreover, it has been de- scribed as one of the rare circulating BMPs. In this paper, we will review the recent literature on BMP9 and the different avenues for future research in that field. Our primary scope is to review its relation to bone formation and to elaborate on the available literature on other systems.

Fong et al. recently demonstrated in vitro that rhBMP9 can also augment bone resorption. This increase was shown to be functional and not related to osteoclast formation. Furthermore, rhBMP9 could alter the intrinsic apoptosis pathway and increase survival of osteoclasts. The effect of rhBMP9 on osteoclast was explained by the presence of ALK1 and BMPRII co-receptors and their activation of the Smad 1/5/8 and non-smad MAPK/ERK pathways. These results show for the first time that BMP9 can directly affect human osteoclasts, acting on their function and their survival.

Insulin resistance is a systemic multifactorial impairment of glucose uptake. Muscle, a glucose consuming organ, needs Akt2 to be able to activate insulin-induced glucose uptake and this pathway seems to be severely impaired in insulin resistance. Interestingly, a combination of bioinformatic and high- throughput functional analyses have shown BMP9 to be the first hepatic factor to regulate blood glucose concencentration. Moreover, this effect was thought to be mediated by activation of Akt kinase in differentiated myotubes. Then, it has been demonstrated that recombinant BMP9 (1 and 5 mg/kg) improves glucose homeostasis in vivo in diabetic and non-diabetic rodents. The mechanism relied on the upregulation of Smad5 and Akt2 in differentiated rats myotubes. On the opposite side, Smad5 was downregulated in myotubes by de xamethasone, a well known hyperglycemia inducer and Smad5 knockdown in rats decreased Akt2 expression and phosphorylation leading to a decrease in insulin-induced glucose uptake by myotubes. It was then hypothesized that Smad5 regulated glucose uptake in skeletal muscle through Akt2 expression and phosphorylation. These findings also revealed Smad5 as a potential target for the treatment of type 2 diabetes. Hence, BMP9 could be seen as a potential activator of Smad5 for that purpose.

BMP9 is a major member of the TGF- superfamily that is implied in many fundamental developmental and pa- thologic processes. Future research will certainly bring answers to the many questions left open, and those an- swers will unquestionably lead to clinical applications.

Understanding Bone Loss

Max Stanley Chartrand, PhD.
DigiCare® Behavioral Research

During their lifetimes, at least half of those over age 50 will be at risk of developing osteoporosis. When we speak of bone loss we are primarily speaking of three diagnostic stages: Osteoarthritis (1-2% loss per annum), Osteopenia (3% per annum), and Osteoporosis (4-5%+ per annum) that are caused almost entirely by diet, hydration, lifestyle, medications, and environ-mental stressors.

Human bones are highly vascularized and mineralized tissues that are constantly being shaped and developed by cells called osteoblasts and torn down and resorbed by cells called osteoclasts. Recent research confirms that throughout one’s lifespan it is osteoblast activity that controls and dictates osteoclast activity as long as the body receives the nutrients it requires to maintain homeostasis. Growing children, for instance, have a far greater abundance of osteoblasts than of osteoclasts. By the time they reach young adulthood (at about age 26 for men, 22 for women) osteoclasts increase while osteoblasts slow down. Even so, humans of any age can increase osteoblast activity and slow the formation of osteoclasts through weight bearing exercise and other methods.

Long bone

Long bone

Long bone
The problem of bone shrinkage and decline in strength presents most often in health states involving:

  1. Sedentary Lifestyle, making weight bearing exercise a frontline defense against bone loss for everyone.
  2. Acidosis (low pH), from a diet that is nutritionally lacking, genetically modified, degerminated, irradiated, laden with toxins & over-processed.
  3. Chronic dehydration from too much caffeine and high fructose corn syrup (a GMO) and not enough water that is both ionized and alkalized.
  4. Lacking in calcium that is live, ionically charged, as well as phosphorus, magnesium, boron, and other minerals comprised in human bones. On the other hand, commercially available calcium causes atherosclerosis, kidney stones, bone spurs, cataracts, and yet MORE bone loss!
  5. Taking prescription medications, especially acid reflux meds, NSAIs and steroids. These and more interfere with osteoblast activity and weaken immunology. Osteoporosis meds prevent living bone mass!
  6. Unhealed injuries and deterioration of the spine, such as compression fractures (>50% of the US adult population), spinal stenosis, kyphosis, and scoliosis. These cause even more rapid loss of bone mass.
  7. Subclinical infections: tooth and gum sepsis, around artificial joints, keratosis obturans, kidney and bladder infections, neuropathies, and osteomyelitis as a result of injuries and/or shock to the bones.
  8. Heavy metal accumulations: lead, mercury, cadmium, arsenic, formaldehyde, cyanide, etc. found in the drinking water, fresh foods, cosmetics, paints, fuels, and a host of commonly used products.
  9.  Lifestyle Substances– Smoking, alcohol, excess coffee, marijuana, opium (including opiate pain killers), diet sodas, caffeine drinks.

The Kinetics of Skeletal Remodeling

Jan 1, 1966  by Lent C. Johnson
Semin Musculoskelet Radiol. 2000;4(1):1-15.

Bone tumor dynamics: an orthopedic pathology perspective.
Johnson LC1, Vinh TN, Sweet DE.

The diagnosis and classification of primary bone tumors remains as much a challenge today as it has for the last 80 plus years. Although pathology is invariably equated with the image of a diagnostic microscope, the vast majority of diagnoses are made grossly with the unaided eye, as are the tissue specimens selected for microscopic “confirmation.” Radiologic studies, particularly plain radiographs, remain the gold standard in gross pathologic diagnosis of the skeleton. Today, confirmation and final classification continue as the pathologist’s domain, but perhaps not for long, considering the evolving ancillary imaging techniques and progressive sophistication of magnetic resonance (MR) imaging. The bone tumor cases collected and compiled by Ernest Codman, M.D. during the second through fourth decades of this century formed the basis of the first tumor registry. The Codman Bone Sarcoma Registry demonstrated among other things the importance of radiographic/pathologic correlation, underscoring the reliability of a bone tumor’s location, margin (host bone/tumor interface), periosteal reaction, and matrix patterns as an accurate guide to classification and likely future biologic behavior. “A General Theory of Bone Tumors,” written by Lent C. Johnson nearly 50 years ago and published in the Bulletin of The New York Academy of Medicine (February 1953, second series, vol. 29, no. 2, pp. 164-171), provided a conceptual cellular approach to the understanding bone tumor dynamics reinforcing radiologic/pathologic correlation as a reliable diagnostic tool. At the time of Dr. Lent C. Johnson’s death (1910-1998), he was literally working on an updated version of his original article, the latter of which is being reprinted as the core of this illustrated revision. Our continued experience with bone tumors over the past five decades has only served to validate, on a daily basis, the fundamental principles outlined in Johnson’s original article. In like fashion, it is important to keep in mind that terminology and nomenclature has also evolved since 1953, despite a continued inability to achieve complete consensus.
PMID:  11061688    http://www.ncbi.nlm.nih.gov/pubmed/11061688

Interactions between adrenal-regulatory and calcium-regulatory hormones in human health

Brown, J.M., Vaidya, A.

Curr Opinion in Endocr, Diabetes and Obesity 2014; 21 (3), pp. 193-201

Purpose of review: To summarize the evidence characterizing the interactions between adrenal-regulating and calcium-regulating hormones, and the relevance of these interactions to human cardiovascular and skeletal health. Recent findings: Human studies support the regulation of parathyroid hormone (PTH) by the renin-angiotensin-aldosterone system (RAAS): angiotensin II may stimulate PTH secretion via an acute and direct mechanism, whereas aldosterone may exert a chronic stimulation of PTH secretion.
Studies in primary aldosteronism, congestive heart failure, and chronic
kidney disease have identified associations between hyperaldosteronism, hyperparathyroidism, and bone loss, which appear to improve when
inhibiting the RAAS. Conversely, elevated PTH and insufficient vitamin D
status have been associated with adverse cardiovascular outcomes, which
may be mediated by the RAAS. Studies of primary hyperparathyroidism implicate PTH-mediated stimulation of the RAAS, and recent evidence shows that the vitamin D-vitamin D receptor complex may negatively regulate renin expression and RAAS activity. Ongoing human interventional studies are evaluating the influence of RAAS inhibition on PTH and the influence of vitamin D receptor agonists on RAAS activity. Summary: Although previously considered independent endocrine systems, emerging evidence supports a complex web of interactions between adrenal-regulating and calcium-regulating hormones, with implications for human cardiovascular and
skeletal health.

Backbone modification of a polypeptide drug alters duration of action in vivo

Cheloha, R.W., Maeda, A., Dean, T., Gardella, T.J., Gellman, S.H.

Nature Biotechnology 2014; 32 (7), pp. 653-655 http://dx.doi.org/doi:10.1038/nbt.2920

Systematic modification of the backbone of bioactive polypeptides through amino acid residue incorporation could provide a strategy for generating molecules with improved drug properties, but such alterations can result in lower receptor affinity and potency. Using an agonist of parathyroid hormone receptor-1 (PTHR1), a G protein-coupled receptor in the B-family, we present an approach for residue replacement that enables both high activity and improved pharmacokinetic properties in vivo.

Mouse and human BAC transgenes recapitulate tissue-specific expression
of the vitamin D receptor in mice and rescue the VDR-null phenotype

Lee, S.M., Bishop, K.A., Goellner, J.J., O’Brien, C.A., Pike, J.W.
Endocrinology 2014; 155 (6), pp. 2064-2076
http://dx.doi.org/10.1210/en.2014-1107

The biological actions of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) are mediated by the vitamin D receptor (VDR), which is expressed in numerous target tissues in a cell type-selective manner. Recent studies using genomic analyses and recombined bacterial artificial chromosomes (BACs) have defined the specific features of mouse and human VDR gene loci in vitro. In the current study, we introduced recombined mouse and human VDR BACs as transgenes into mice and explored their expression capabilities in vivo. Individual transgenic mouse strains selectively expressed BAC derived mouse or human VDR proteins in appropriate vitamin D target tissues, thereby recapitulating the tissue-specific expression of endogenous mouse VDR. The mouse VDR transgene was also regulated by 1,25(OH)2D3 and dibutyryl-cAMP. When crossed into a VDR-null mouse background, both transgenes restored wild-type basal as well as 1,25(OH)2D3-inducible gene expression patterns in the appropriate tissues. This maneuver resulted in the complete rescue of the aberrant phenotype noted in the VDR-null mouse, including systemic features associated with altered calcium and phosphorus homeostasis and disrupted production of parathyroid hormone and fibroblast growth factor 23, and abnormalities associated with the skeleton, kidney, parathyroid gland, and the skin. This study suggests that both mouse and human VDR transgenes are capable of recapitulating basal and regulated expression of the VDR in the appropriate mouse tissues and restore 1,25(OH)2D 3 function. These results provide a baseline for further dissection of mechanisms integral to mouse and human VDR gene expression and offer the potential to explore the consequence of selective mutations in VDR proteins in vivo.

The sclerostin-independent bone anabolic activity of intermittent PTH treatment is mediated by T-cell-produced Wnt10β

Li, J.-Y., Walker, L.D., Tyagi, A.M., (…), Neale Weitzmann, M., Pacifici, R
Journal of Bone and Mineral Research 2014; 29 (1), pp. 43-54
http://onlinelibrary.wiley.com/doi/10.1002/jbmr.2044/pdf

Both blunted osteocytic production of the Wnt inhibitor sclerostin (Scl) and increased T-cell production of the Wnt ligand Wnt10b contribute to the bone anabolic activity of intermittent parathyroid hormone (iPTH) treatment. However, the relative contribution of these mechanisms is unknown. In this study, we modeled the repressive effects of iPTH on Scl production in mice by treatment with a neutralizing anti-Scl antibody (Scl-Ab) to determine the contribution of T-cell-produced Wnt10b to the Scl-independent modalities of action of iPTH. We report that combined treatment with Scl-Ab and iPTH was more potent than either iPTH or Scl-Ab alone in increasing stromal cell production of OPG, osteoblastogenesis, osteoblast life span, bone turnover, bone mineral density, and trabecular bone volume and structure in mice with T cells capable of producing Wnt10b. In T-cell-null mice and mice lacking T-cell production of Wnt10b, combined treatment increased bone turnover significantly more than iPTH or Scl-Ab alone. However, in these mice, combined treatment with Scl-Ab and iPTH was equally effective as Scl-Ab alone in increasing the osteoblastic pool, bone volume, density, and structure. These findings demonstrate that the Scl-independent activity of iPTH on osteoblasts and bone mass is mediated by T-cell-produced Wnt10b. The data provide a proof of concept of a more potent therapeutic effect of combined treatment with iPTH and Scl-Ab than either alone.

N-cadherin restrains PTH activation of Lrp6/β-catenin signaling and osteoanabolic action

Revollo, L., Kading, J., Jeong, S.Y., (…), Mbalaviele, G., Civitelli, R.
Journal of Bone and Mineral Research 2015; 30 (2), pp. 274-28

Interaction between parathyroid hormone/parathyroid hormone-related peptide receptor 1 (PTHR1) and low-density lipoprotein receptor-related protein 6 (Lrp6) is important for parathyroid hormone (PTH) signaling and anabolic action. Because N-cadherin has been shown to negatively regulate canonical Wnt/β-catenin signaling, we asked whether N-cadherin alters PTH signaling and stimulation of bone formation. Ablation of the N-cadherin gene (Cdh2) in primary osteogenic lineage cells resulted in increased Lrp6/PTHR1 interaction in response to PTH1-34, associated with enhanced PTH-induced PKA signaling and PKA-dependent β-catenin C-terminus phosphorylation, which promotes β-catenin transcriptional activity. β-catenin C-terminus phosphorylation was abolished by Lrp6 knockdown. Accordingly, PTH1-34 stimulation of Tcf/Lef target genes, Lef1 and Axin2, was also significantly enhanced in Cdh2-deficient cells. This enhanced responsiveness to PTH extends to the osteo-anabolic effect of PTH, as mice with a conditional Cdh2 deletion in Osx+ cells treated with intermittent doses of PTH1-34 exhibited significantly larger gains in trabecular bone mass relative to control mice, the result of accentuated osteoblast activity. Therefore, N-cadherin modulates Lrp6/PTHR1 interaction, restraining the intensity of PTH-induced β-catenin signaling, and ultimately influencing bone formation in response to intermittent PTH administration.

EphrinB2 signaling in osteoblasts promotes bone mineralization by preventing apoptosis

Tonna, S., Takyar, F.M., Vrahnas, C., (…), Martin, T.J., Sims, N.A.
FASEB Journal 2014; 28 (10), pp. 4482-4496 10.1096/fj.14-254300

Cells that form bone (osteoblasts) express both ephrinB2 and EphB4, and previous work has shown that pharmacological inhibition of the ephrinB2/ EphB4 interaction impairs osteoblast differentiation in vitro and in vivo. The purpose of this study was to determine the role of ephrinB2 signaling in the osteoblast lineage in the process of bone formation. Cultured osteoblasts from mice with osteoblast-specific ablation of ephrinB2 showed delayed expression of osteoblast differentiation markers, a finding that was reproduced by ephrinB2, but not EphB4, RNA interference. Microcomputed tomography, histomorphometry, and mechanical testing of the mice lacking ephrinB2 in osteoblasts revealed a 2-fold delay in bone mineralization, a significant reduction in bone stiffness, and a 50% reduction in osteoblast differentiation induced by anabolic parathyroid hormone (PTH) treatment, compared to littermate sex- and age-matched controls. These defects were associated with significantly lower mRNA levels of late osteoblast differentiation markers and greater levels of osteoblast and osteocyte apoptosis, indicated by TUNEL staining and transmission electron microscopy of bone samples, and a 2-fold increase in annexin V staining and 7-fold increase in caspase 8 activation in cultured ephrinB2 deficient osteoblasts. We conclude that osteoblast differentiation and bone strength are maintained by antiapoptotic actions of ephrinB2 signaling within the osteoblast lineage.-
Bone involvement in primary hyperparathyroidism and changes after parathyroidectomy

Rolighed, L., Rejnmark, L., Christiansen, P.
European Endocrinology 2014; 10 (1), pp. 84-87

Parathyroid hormone (PTH) is produced and secreted by the parathyroid glands and has primary effects on kidney and bone. During the pathological growth of one or more parathyroid glands, the plasma level of PTH increases and causes primary hyperparathyroidism (PHPT). This disease is normally characterized by hyperparathyroid hypercalcemia. In PHPT a continuously elevated PTH stimulates
the kidney and bone causing a condition with high bone turnover, elevated plasma calcium and increased fracture risk. If bone resorption is not followed by a balanced formation of new bone, irreversible bone loss may occur in these patients. Medical treatment can help to minimize the loss of bone but the cure of PHPT is by parathyroidectomy. After operation, bone mineral density increases during the return to normal bone metabolism. Supplementation with calcium and vitamin D after operation may improve the normalization to normal bone metabolism with a secondary reduction in fracture risk.

Primary hyperparathyroidism and the skeleton

Mosekilde, L.
Clinical Endocrinology 2008; 69 (1), pp. 1-19
http://dx.doi.org:/10.1111/j.1365-2265.2007.03162.x

Today, primary hyperparathyroidism (PHPT) in the developed countries is typically a disease with few or no obvious clinical symptoms. However, even in the asymptomatic cases the endogenous excess of PTH increases bone turnover leading to an insidious reversible loss of cortical and trabecular bone because of an expansion of the remodelling space and an irreversible loss of cortical bone due to increased endocortical resorption. In contrast trabecular bone structure and integrity to a large extent is maintained and there may be a slight periosteal expansion. Most studies have reported decreased bone mineral density (BMD) in PHPT mainly located at cortical sites, whereas sites rich in trabecular bone only show a modest reduction or even a slight increase in BMD. The frequent occurrence of vitamin D insufficiency and deficiency in PHPT and increased plasma FGF23 levels may also contribute to the decrease in BMD. The effect of smoking is unsolved. Epidemiological studies have shown that the relative risk of spine and nonspine fractures is increased in untreated PHPT starting up to 10 years before the diagnosis is made. Successful surgery for PHPT normalizes bone turnover, increases BMD and decreases fracture risk based on larger epidemiological studies. However, 10 years after surgery fracture risk appears to increase again due to an increase in forearm fractures. There are no randomized controlled studies (RCTs) demonstrating a protective effect of medical treatment on fracture risk in PHPT. Less conclusive studies suggest that vitamin D supplementation may have a beneficial effect on plasma PTH and BMD in vitamin D deficient PHPT patients. Hormone replacement therapy (HRT) and maybe SERM appear to reduce bone turnover and increase BMD. However, their nonskeletal side-effects preclude their use for this purpose. Bisphosphonates reduce bone turnover and increase BMD in PHPT as in osteoporosis and may be a therapeutical option in selected patients with low BMD. Obviously, there is a need for larger RCTs with fractures as end-points that appraise this possibility. Calcimimetics reduce plasma calcium and PTH in PHPT but has no beneficial effect on bone turnover or BMD. In symptomatic hypercalcemic PHPT with low BMD where curative surgery is impossible or contraindicated a combination of a calcimimetic and a bisphosphonate may be an undocumented therapeutical option that needs further evaluation.

Current Issues in the Presentation of Asymptomatic Primary Hyperparathyroidism: Proceedings of the Fourth International Workshop

Shonni J. Silverberg, Bart L. Clarke, Munro Peacock, Francisco Bandeira, et al. The Journal of Clinical Endocrinology & Metabolism 2014; 99(10) http://dx.doi.org/10.1210/jc.2014-1415

Objective: This report summarizes data on traditional and nontraditional manifestations of primary hyperparathyroidism (PHPT) that have been published since the last International Workshop on PHPT.

Participants: This subgroup was constituted by the Steering Committee to address key questions related to the presentation of PHPT. Consensus was established at a closed meeting of the Expert Panel that followed.

Evidence: Data from the 5-year period between 2008 and 2013 were
presented and discussed to determine whether they support changes in recommendations for surgery or nonsurgical follow-up.

Consensus Process: Questions were developed by the International Task
Force on PHPT. A comprehensive literature search for relevant studies was undertaken. After extensive review and discussion, the subgroup came to agreement on what changes in the recommendations for surgery or nonsurgical follow-up of asymptomatic PHPT should be made to the Expert Panel.

Conclusions:

1) There are limited new data available on the natural history of
asymptomatic PHPT. Although recognition of normocalcemic PHPT
(normal serum calcium with elevated PTH concentrations; no secondary
cause for hyperparathyroidism) is increasing, data on the clinical
presentation and natural history of this phenotype are limited.
2) Although there are geographic differences in the predominant
phenotypes of PHPT (symptomatic, asymptomatic, normocalcemic),
they do not justify geography-specific management guidelines.
3) Recent data using newer, higher resolution imaging and analytic
methods have revealed that in asymptomatic PHPT, both trabecular
bone and cortical bone are affected.
4) Clinically silent nephrolithiasis and nephrocalcinosis can be detected
by renal imaging and should be listed as a new criterion for surgery.
5) Current data do not support a cardiovascular evaluation or surgery
for the purpose of improving cardiovascular markers, anatomical or
functional abnormalities.
6) Some patients with mild PHPT have neuropsychological complaints
and cognitive abnormalities, and some of these patients may benefit
from surgical intervention. However, it is not possible at this time to
predict which patients with neuropsychological complaints or cognitive
issues will improve after successful parathyroid surgery.

Sclerosing Bone Dysplasias: Leads Toward Novel Osteoporosis Treatments

Igor Fijalkowski, Eveline Boudin, Geert Mortier, Wim Van Hul
Current Osteoporosis Reports Sept 2014; 12(3), pp 243-251
http://dx.doi.org:/10.1007/s11914-014-0220-5

Sclerosing bone dysplasias are a group of rare, monogenic disorders characterized by increased bone density resulting from the disturbance in the fragile equilibrium between bone formation and resorption. Over the last decade, major contributions have been made toward better understanding of the pathogenesis of these conditions. These studies provided us with important insights into the bone biology and yielded the identification of numerous drug targets for the prevention and treatment of osteoporosis. Here, we review this heterogeneous group of disorders focusing on their utility in the development of novel osteoporosis therapies.

Clinical development of neridronate: potential for new applications

Gatti D, Rossini M, Viapiana O, Idolazzi L, Adami S
Ther & Clin Risk Manag Apr 2013; 2013(9): Pages 139—147

Neridronate is an aminobisphosphonate, licensed in Italy for the treatment
of osteogenesis imperfecta (OI) and Paget’s disease of bone (PDB).  A characteristic property of neridronate is that it can be administered both intravenously and intramuscularly, providing a useful system for administration in homecare. In this review, we discuss the latest clinical results of neridronate administration in OI and PDB, as well as in osteoporosis and other conditions. We will focus in particular on the latest evidence of the effect of neridronate on treatment of complex regional pain syndrome type I.

Disorders of bone remodeling

Feng, X., McDonald, J.M.
Ann Rev of Pathol: Mechanisms of Disease 2011; 6, pp. 121-145
http://dx.doi.org:/10.1146/annurev-pathol-011110-130203

The skeleton provides mechanical support for stature and locomotion, protects vital organs, and controls mineral homeostasis. A healthy skeleton must be maintained by constant bone modeling to carry out these crucial functions throughout life. Bone remodeling involves the removal of old or damaged bone by osteoclasts (bone resorption) and the subsequent replacement of new bone formed by osteoblasts (bone formation). Normal bone remodeling requires a tight coupling of bone resorption to bone formation to guarantee no alteration in bone mass or quality after each remodeling cycle. However, this important physiological process can be derailed by a variety of factors, including menopause-associated hormonal changes, age-related factors, changes in physical activity, drugs, and secondary diseases, which lead to the development of various bone disorders in both women and men. We review the major diseases of bone remodeling, emphasizing our current understanding of the underlying pathophysiological mechanisms.

Paget’s disease and hypercalcemia: Coincidence or causal relationship?

Green, I., Altman, A.
Harefuah 2009; 148 (10), pp. 708-710

Paget’s disease is a chronic disease in which osteoclast mediated bone resorption precedes imperfect osteoblast mediated bone repair. Symptoms include bone pain, pathological fractures, osteoarthritis and neurological symptoms. There is evidence that genetic and viral component are involved in the etiology. Hypercalcemia is rare and when it is diagnosed, primary hyperparathyroidism should be ruled out. The authors present a patient with Paget’s disease and concomitant hypercalcemia. Evaluation for hypercalcemia revealed an adenoma of the parathyroid. However, despite the removal of the adenoma, the symptoms persisted. Previous studies
showed that hyperparathyroidism causes hypercalcemia in Paget’s disease patients. Removal of the adenoma led to improvement in calcium and alkaline phosphatase (ALP) levels but clinical improvement is seen only in patients with high calcium level prior to the operation. This leads to the assumption that symptoms of Paget’s disease are due to osteoclast hypersensitivity to parathyroid hormone (PTH) and by removing the adenoma the osteoclast activity is also reduced. In summary, the most common cause of hypercalcemia in Paget’s disease patients is hyperparathyroidism and adenectomy may improve the biochemical and sometimes also the clinical symptoms of Paget’s disease.

Signaling networks that control the lineage commitment and differentiation of bone cells

Soltanoff, C.S., Yang, S., Chen, W., Li, Y.-P.
Critical Reviews in Eukaryotic Gene Expression 2009; 19 (1), pp. 1-46

Osteoblasts and osteoclasts are the two major bone cells involved in the bone remodeling process. Osteoblasts are responsible for bone formation while osteoclasts are the bone-resorbing cells. The major event that triggers osteogenesis and bone remodeling is the transition of mesenchymal stem cells into differentiating osteoblast cells and monocyte/macrophage precursors into differentiating osteoclasts. Imbalance in differentiation and function of these two cell types will result in skeletal diseases such as osteoporosis, Paget’s disease, rheumatoid arthritis, osteopetrosis, periodontal disease, and bone cancer metastases.
Osteoblast and osteoclast commitment and differentiation are controlled by complex activities involving signal transduction and transcriptional regulation of gene expression. Recent advances in molecular and genetic studies using gene targeting in mice enable a better understanding of the multiple factors and signaling networks that control the differentiation process at a molecular level.
This review summarizes recent advances in studies of signaling transduction pathways and transcriptional regulation of osteoblast and osteoclast cell lineage commitment and differentiation. Understanding the signaling networks that control the commitment and differentiation of bone cells will not only expand our basic understanding of the molecular mechanisms of skeletal development but will also aid our ability to develop therapeutic means of intervention in skeletal diseases.

Salmon calcitonin: a review of current and future therapeutic indications

  1. H. Chesnut III, M. Azria, S. Silverman, M. Engelhardt, M. Olson, L. Mindeholm Osteoporosis International 2008; 19(4), pp 479-491
    http://dx.doi.org:/10.1007/s00198-007-0490-1

Salmon calcitonin, available as a therapeutic agent for more than 30 years, demonstrates clinical utility in the treatment of such metabolic bone diseases as osteoporosis and Paget’s disease, and potentially in the treatment of osteoarthritis. This review considers the physiology and pharmacology of salmon calcitonin, the evidence based research demonstrating efficacy and safety of this medication in postmenopausal osteoporosis with potentially an effect on bone quality to explain its abilities to reduce the risk of spine fracture, the development of an oral salmon calcitonin preparation, and the therapeutic rationale for this preparation’s chondroprotective effect in osteoarthritis.

Pharmacotherapies to Manage Bone Loss-Associated Diseases:  A Quest for the Perfect Benefit-to-Risk Ratio

Valverde

Current Medicinal Chemistry : 15 (3): Pages 284-304
http://dx.doi.org:/10.2174/092986708783497274

In this review, benefits and side-effects of current and emerging therapies to treat and prevent pathological bone loss are described. Bisphosphonates are the antiresorptive compounds most widely used in the treatment of bone-loss associated diseases. They are generally well-tolerated although have recently been associated with osteonecrosis of the jaw and other complications. Therapies modulating estrogen receptor activation are indicated in the prevention and treatment of either breast cancer or osteoporosis in postmenopausal women. Thus, hormone replacement therapy is effective in prevention of osteoporosis, but its long-term use can increase the risk of breast cancer, stroke and embolism. Tamoxifen benefits all stages of breast cancer, but its use may lead to uterine cancer and thromboembolism. Raloxifene is approved in prevention of breast cancer and treatment of postmenopausal osteoporosis, but its use can increase the risk of fatal stroke. Aromatase inhibitors are superior to tamoxifen at advanced stages of disease and as adjuvants, but their use increase fracture incidence. Fulvestrant is as effective as aromatase inhibitors in the treatment of advanced breast cancer and does not cause bone fractures. Another antiresorptive available for the treatment of postmenopausal osteoporosis, Pagets disease and hypercalcemia is calcitonin, which also exhibits analgesic effects. A promising antiresorptive agent currently in clinical trials is denosumab. Aditional therapies for osteoporosis that decrease fracture risk consist of PTH-like anabolic agents and the dual action bone agent strontium ranelate. Antiseptics and antibiotics are used extensively in periodontal disease intervention to target bacterial biofilm, although hostdirected therapies are also being developed. – See more at: http://www.eurekaselect.com/66301/article#sthash.EGNCH4Eu.dpuf

Parathyroid Hormone An Anabolic Treatment for Osteoporosis

Paul Morley, James F. Whitfield and Gordon E. Willick
Current Pharmaceutical Design Pages 671-687
http://dx.doi.org:/10.2174/1381612013397780

Osteoporosis is a disease characterised by low bone mass, structural deterioration of bone and increased risk of fracture. The prevalence, and cost, of osteoporosis is increasing dramatically with our ageing population and the World Health Organization now considers it to be the second-leading healthcare problem. All currently approved therapies for osteoporosis (eg., estrogen, bisphosphonates, calcitonin and selective estrogen receptor modulators) are anti-resorptive agents that act on osteoclasts to prevent further bone loss. A new class of bone anabolic agent capable of building mechanically strong new bone in patients with established osteoporosis is
in development. While the parathyroid hormone (PTH) is classically considered to be a bone catabolic agent, when delivered intermittently at low doses PTH potently stimulates cortical and trabecular bone growth in animals humans. The native hPTH-(1-84) and its osteogenic fragment, hPTH-(1-34), have already entered Phase III clinical trials. Understanding the mechanism of PTHs osteogenic actions has led to the development of smaller PTH analogues which can also build mechanically normal bone in osteopenic rats. These new PTH analogues are promising candidates for treating osteoporosis in humans as they are as efficacious as hPTH-(1-84) and hPTH-(1-34), but there is evidence that they may have considerably less ability to induce hypercalcemia, the major side effect of PTH therapy. In addition to treating osteoporosis, PTHs may be used to promote fracture healing, to restore bone loss in immobilized patients, or following excessive glucocorticoid or prolonged spaceflight, and to treat psoriasis. http://www.eurekaselect.com/65008/article#sthash.FWa67NrB.dpuf

Effects of Parathyroid Hormone on Cancellous Bone Mass and Structure in Osteoporosis

Naohisa Miyakoshi
Current Pharmaceutical Design  ;10(21): Pages 2615-2627
http://dx.doi.org:/10.2174/1381612043383737

Parathyroid hormone (PTH) is the major hormonal regulator of calcium homeostasis. PTH is a potent stimulator of bone formation and can restore bone to an osteopenic skeleton, when administered intermittently. Osteoblasts are the primary target cells for the anabolic effects of PTH in bone tissue. Anabolic effects of PTH on bone have been demonstrated in animals and humans, by numerous measurement techniques including bone mineral density and bone histomorphometry. Clinically, the most important aspect of treatment for osteoporosis is prevention of fractures. Microstructural alterations, such as loss of trabecular connectivity, have been implicated in increased propensity for fracture. Recent two-dimensional (2D) and three-dimensional (3D) assessments of cancellous bone structure have shown that PTH can re-establish lost trabecular connectivity in animals and humans.
These results provide new insight into the positive clinical effects of PTH in osteoporosis. In recent randomized controlled clinical trials of intermittent
PTH treatment, PTH decreased incidence of vertebral and non-vertebral fractures
in postmenopausal women. Thus, PTH shows strong potential as therapy for osteoporosis. However, 2D and 3D structural analysis of advanced osteopenia in animals has shown that there is a critical limit of trabecular connectivity and bone strength below which PTH cannot completely reverse the condition. Given that PTH treatment fails to completely restore trabecular connectivity and bone strength in animals with advanced osteopenia, early treatment of osteoporosis appears important and efficacious for preventing fractures caused by decreased bone strength resulting from decreased trabecular connectivity. – See more at: http://www.eurekaselect.com/62780/article#sthash.OnoaRPyh.dpuf

Clinical applications of RANK-ligand inhibition

Romas, E.
Internal Medicine Journal 2009; 39 (2), pp. 110-116
http://dx.doi.org:/10.1111/j.1445-5994.2008.01732.x

An enhanced rate of bone remodelling fuelled by osteoclastogenesis mediates diseases such as osteoporosis, arthritic bone destruction, Paget’s disease and malignancy-induced bone loss. Thus, the control of osteoclastogenesis is of major clinical importance. The receptor activator of nuclear factor κB (RANK); its ligand, RANKL and decoy receptor, osteoprotegerin, are critical determinants of osteoclastogenesis, and increased RANK signalling is involved in several bone diseases, providing the rationale for RANKL inhibition. The effects of RANKL inhibition are being witnessed in clinical trials of neutralizing fully human monoclonal antibodies that target RANKL (e.g. denosumab) and which induce profound and sustained inhibition of bone resorption. The relative efficacy, cost-effectiveness and side-effects of targeted RANKL inhibition compared with conventional antiresorptive drugs (i.e. bisphosphonates) should be resolved by clinical trials in coming years.

Clinical development of neridronate: potential for new applications

Davide Gatti, M Rossini, O Viapiana, L Idolazzi, SAdami
Therapeutics and Clinical Risk Management 2013:9 139–147
http://dx.doi.org/10.2147/TCRM.S35788

Neridronate is an aminobisphosphonate, licensed in Italy for the treatment of osteogenesis imperfecta (OI) and Paget’s disease of bone (PDB). A characteristic property of neridronate is that it can be administered both intravenously and intramuscularly, providing a useful system for administration in homecare. In this review, we discuss the latest clinical results of neridronate administration in OI and PDB, as well as in osteoporosis and other conditions. We will focus in particular on the latest evidence of the effect of neridronate on treatment of complex regional pain syndrome type I.

The Sclerostin‐Independent Bone Anabolic Activity of Intermittent PTH Treatment Is Mediated by T‐Cell–Produced Wnt10β

Jau‐Yi Li, Lindsey D Walker, Abdul Malik Tyagi, Jonathan Adams, et al.
Journal of Bone and Mineral Research, Jan 2014; 29(1): pp 43–54
http://dx.doi.org:/10.1002/jbmr.2044

Both blunted osteocytic production of the Wnt inhibitor sclerostin (Scl) and increased T‐cell production of the Wnt ligand Wnt10β contribute to the bone anabolic activity of intermittent parathyroid hormone (iPTH) treatment. However, the relative contribution of these mechanisms is unknown. In this study, we modeled the repressive effects of iPTH on Scl production in mice by treatment with a neutralizing anti‐Scl antibody (Scl‐Ab) to determine the contribution of T‐cell–produced Wnt10β to the Scl‐independent modalities of action of iPTH. We report that combined treatment with Scl‐Ab and iPTH was more potent than either iPTH or Scl‐Ab alone in increasing stromal cell production of OPG, osteoblastogenesis, osteoblast life span, bone turnover, bone mineral density, and trabecular bone volume and structure in mice with T cells capable of producing Wnt10β. In T‐cell–null mice and mice lacking T‐cell production of Wnt10β, combined treatment increased bone turnover significantly more than iPTH or Scl‐Ab alone. However, in these mice, combined treatment with Scl‐Ab and iPTH was equally effective as Scl‐Ab alone in increasing the osteoblastic pool, bone volume, density, and structure. These findings demonstrate that the Scl‐independent activity of iPTH on osteoblasts and bone mass is mediated by T‐cell–produced Wnt10β. The data provide a proof of concept of a more potent therapeutic effect of combined treatment with iPTH and Scl‐Ab than either alone.

Treatment of Paget’s disease with hypercalcemia

Donald H. Gutteridge – Letter to the Editor
Bone 12 Jan 2006; 39(668)
http://dx.doi.org:/10.1016/j.bone.2006.01.165

Selby et al. [7] “Guidelines on the management of Paget’s disease of bone” produced a very helpful review, with 139 references. I take issue however with their approach to the clinical problem of concurrent Paget’s and hypercalcemia.
Firstly, the combination is not rare. Of 1836 literature and personally reported unselected patients with Paget’s disease, 90 had concurrent hypercalcemia due to primary hyperparathyroidism [PHPT], i.e., 4.9% [4]. The number with unspecified hypercalcemia would have exceeded 5%.                                     Secondly, the authors give similar weight to immobilization and PHPT as causes. Immobilization as a cause of hypercalcemia in Paget’s disease is rare [4,3]. The former paper studied 184 consecutive new referrals with Paget’s disease over 15 years. Hypercalcemia was present in 21: two had malignancy (multiple myeloma, secondary cancer); the remaining 19 had biochemical PHPT with most confirmed by neck exploration; none had hypercalcemia of immobilization. Gillespie [3] reported two patients who died following pagetic fractures with immobilization. One was diagnosed and treated as immobilization hypercalcemia; both had large parathyroid adenomas at autopsy.
Thirdly, they have recommended that “patients with Paget’s disease and hypercalcemia should be treated with bisphosphonate”. Since most patients with this combination have PHPT, since bisphosphonate treatment of Paget’s disease is associated with parathyroid hormone (PTH) stimulation [5] and since activation of Paget’s disease occurs with increased PTH [2], it seems reasonable to exclude PHPT (and other causes— e.g., milk alkali syndrome and vitamin D toxicity) and consider neck exploration before bisphosphonate treatment. The response to parathyroidectomy can be profound—and is predictable. In those with PHPT there is a significant linear relationship between preoperative severity (plasma calcium corrected for plasma albumin) and postoperative improvement in bone turnover (%fall in plasma alkaline phosphatase) [4]. In those 7 patients with a preoperative calcium >3.0 mmol/l, the postoperative mean fall in plasma alkaline phosphatase was 68%. Bisphosphonate treatment may be an option in those with PHPT and mild asymptomatic hypercalcemia; likewise following a reasonable interval (say 6 months) after successful neck exploration, should increased bone turnover and pagetic symptoms persist.

In those rare cases with the combination of Paget’s disease, hypercalcemia and immobilized pagetic fracture, where other causes of hypercalcemia have been excluded [1,6], bisphosphonate treatment is eminently reasonable.

[1] Bannister P, Roberts M, Sheridan P. Recurrent hypercalcaemia in a young man with mono-ostotic Paget’s disease. Postgrad Med J 1986;62:481–3.
[2] Genuth SM, Klein L. Hypoparathyroidism and Paget’s disease: the effect of parathyroid hormone administration. J Clin Endocrinol Metab 1972;35: 693–9.
[3] Gillespie WJ. Hypercalcaemia in Paget’s disease of bone. Aust N Z J Surg 1979;49:84–6.
[4] Gutteridge DH, Gruber HE, Kermode DG, Worth GK. Thirty cases of concurrent Paget’s disease and primary hyperparathyroidism: sex distribution, histomorphometry, and prediction of the skeletal response to parathyroidectomy. Calcif Tissue Int 1999;65:427–35.
[5] Harinck HIJ, Bijvoet OLM, Blanksma HJ, Dahlinghaus-Nienhuys PJ. Efficacious management with aminobisphosphonate (APD) in Paget’s disease of bone. Clin Orthop Relat Res 1987;217:79–98.
[6] Nathan AW, Ludlam HA, Wilson DW, Dandona P. Hypercalcaemia due to immobilization of a patient with Paget’s disease of bone. Postgrad Med J 1982;58:714–5.
[7] Selby PL, Davie MWJ, Ralston SH, Stone MD. Guidelines on the management of Paget’s disease of bone. Bone 2002;31:10–9.

The authors of the article entitled “Guidelines on the management of Paget’s disease of bone” published in BONE 2002:31:10–9, have elected not to respond to the above letter to the Editor.

Safety of Bisphosphonates in the Treatment of Osteoporosis

Robert R. Recker, E. Michael Lewiecki, Paul D. Miller, James Reiffel
The American Journal of Medicine (2009) 122, S22–S32
http://dx.doi.org:/10.1016/j.amjmed.2008.12.004

In this review 4 experts consider the major safety concerns relating to bisphosphonate therapy for osteoporosis. Specific topics covered are skeletal safety (particularly with respect to atypical fractures and delayed healing), gastrointestinal intolerance, hypocalcemia, acute-phase (i.e., postdose) reactions, chronic musculoskeletal pain, renal safety, and cardiovascular safety (specifically, atrial fibrillation).

The bone-remodeling cycle

The bone-remodeling cycle

The bone-remodeling cycle.
Remodeling of bone in a multicellular bone unit starts with osteoblastic activation of osteoclast differentiation, fusion, and activation (A and B).
When resorption lacunae are formed, the osteoclasts leave the area and mononucleated cells of uncertain origin appear and “clean up” the organic matrix remnants left by the osteoclast, also possibly forming the cement line (dotted line) at the bottom of the lacunae
(C). During the resorption process, coupling factors, including insulin-like growth factor–I and transforming growth factor–β, are released from the bone-extracellular matrix, and these growth factors contribute to the recruitment of osteoblasts to the resorption lacunae and their activation.
(D). The osteoblasts will then fill the lacunae with new bone; when the same amount of bone is formed as is being resorbed, the remodeling process is finished, and the mineralized extracellular matrix will be covered by osteoid and a single-cell layer of osteoblasts
(E). (Reprinted with permission from J Dent Res.6)

SUMMARY

Persistent, long-term antifracture efficacy has been demonstrated for bisphosphonates, and there is no evidence that the antifracture efficacy declines during treatment periods lasting as long as 10 years. Bisphosphonate-induced oversuppression of remodeling and return of fracturing remains a theoretical possibility.
It is likely that a few patients who are potential candidates for bisphosphonate treatment have preexisting oversuppression of bone remodeling. Treatment with a bisphosphonate in these cases would not be helpful and might even be harmful. The problem when encountering a patient with fractures and deciding whether to recommend treatment with a bisphosphonate is that no reliable diagnostic method exists that allows detection of the rare instance of preexisting oversuppression of remodeling.  When pretreatment BMD is not particularly low, that is, not lower than normal or mildly osteopenic, the persistence of fracturing during treatment may mean that oversuppression of remodeling was already present and a change in medication would be appropriate. There is no evidence that bisphosphonate treatment impairs fracture healing. Indeed, there are a substantial number of reports involving animal models, as well as a few human case reports, to suggest that bisphosphonate treatment actually improves fracture healing. In general, it is important to bear in mind the positive benefit-to-risk ratio for this therapeutic class when making treatment recommendations for patients with osteoporosis.

Bisphosphonate Safety:

1.               Gastrointestinal Intolerance,2.               Hypocalcemia,

3.               Acute-Phase Reaction, and

4.               Chronic Bone and Muscle Pain

PTH: Potential role in management of heart failure

  1. Gruson, A. Buglioni, J.C. Burnett Jr.
    Clinica Chimica Acta 433 (2014) 290–296
    http://dx.doi.org/10.1016/j.cca.2014.03.029

Biomarkers play an important role for the diagnosis and prognosis of heart failure (HF), a disease with high morbidity and mortality as well as a huge impact on healthcare budgets. Parathyroid hormone (PTH) is a major systemic calcium-regulating hormone and an important regulator of bone and mineral homeostasis. PTH testing is important for differential diagnosis of calcemia related disorders and for the management of patients with chronic kidney disease. As secondary hyperparathyroidism has been evidenced in HF patients, PTH testing might be relevant in HF patients for risk stratification and more personalized selection of treatment.

Heart failure and neurohormonal activation

Heart failure is a syndrome characterized by increasing prevalence, high morbidity, elevated hospital readmission rate and high mortality. The continuing improvement of diagnosis, prognosis, treatment and management of HF requires a better understanding of the different sub-phenotypes and heterogeneity of this syndrome at the cellular, organ, and systemic level. Neurohormonal activation, one of the hallmarks of HF, plays a significant role in the myocardial and multi-organ adaptation. The comprehensive understanding of neurohormonal activation has allowed the identification of several biomarkers, such as natriuretic peptides, which are now playing an important role in HF management. Beside their contribution to the diagnosis of HF, natriuretic peptides are also relevant for follow-up and prognosis of HF patients.  Nevertheless, natriuretic peptides are more related to ventricular stretch, and biomarkers from other biological pathways like cardiac remodeling might provide additional value for the risk stratification of HF patients. The integration of biomarkers from several pathophysiological pathways along with imaging and genetic testing, might therefore be used to define HF subtypes, responding differently to specific therapeutic actions and contributing to more tailored based approaches.
Abnormalities of bone and mineral metabolism are also found in HF.  Secondary hyperparathyroidism has been evidenced in this context and several recent reports have documented the potential use of parathyroid hormone (PTH) testing for a more personalized management of HF patients. The aim of this article is therefore to review some of the cardiac effects of PTH and the potential role of PTH testing in HF.

Parathyroid hormone: biology and cardiac effects
PTH is one of the major regulators of the bone and mineral metabolism and its secretion is modulated by changes in concentration of calcium in the blood; decreased calcium concentrations stimulating PTH secretion via calcium-sensing receptors in the parathyroid gland. In response to hypocalcemia,
PTH has different targets to increase circulating calcium concentration. A fundamental target is the renal tubule where PTH will increase phosphorus excretion in the proximal tract and will enhance calcium reabsorption from the ascending limb of the loop of Henle to the collecting duct. The proximal renal tubule is also a target where PTH will stimulate the 1-α hydroxylation of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D: this biologically active form of vitamin D acts on the gut to increase absorption of both dietary calcium and phosphorus. Another target of PTH is the osteoclasts, leading to increased bone resorption with release of phosphorus and calcium in the blood.
PTH is a polypeptide containing 84 amino acids secreted by the parathyroid glands after cleavage from preproparathyroid hormone to proparathyroid hormone to the mature hormone. However, it displays several circulating forms and related fragments. PTH is secreted predominantly as an intact molecule, but it is rapidly cleaved in peripheral tissues to amino terminus and carboxy terminus fragments. The amino terminus fragment is biologically active and has a relatively short circulating half-life. The carboxy-terminal species include a 7-84 peptide and a variety of shorter fragments. These fragments can have a longer half-life and accumulate in renal failure. PTH assays measure not only the full-length form of PTH but also isoforms as well as fragments and differences can be observed between assays depending on the antibody specificities.

Cardiac effects of PTH
Primary hyperparathyroidism has been associated with heart diseases, underlying the potential cardiac consequences of increased circulating levels of PTH. Furthermore, as the heart is one of the target organs of PTH, the involvement of this hormone in the pathogenesis of cardiovascular diseases was previously suggested. PTH has different effects on the heart and can stimulate hypertrophy, arrhythmias and a pro-oxidative state. PTH has a direct hypertrophic action on cardiomyocytes. PTH is able, through a direct effect mediated through its receptors, to activate protein kinase C which further stimulates hypertrophic growth and reexpression of fetal type proteins in cardiomyocytes. PTH was also reported as a potent activator of protein kinase A (PKA) and several other downstream effectors related to cardiomyocyte hypertrophy. The hypertrophic effect of PTH on cardiac cells is also reinforced by its ability to stimulate an anti-hypertrophic response, including the natriuretic peptide gene transcription and by the increased of plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP) observed in patients with primary hyperparathyroidism. The hypertrophic effect of PTH on the heart was also evidence by a close relation between PTH levels and left ventricular mass.
In addition to its hypertrophic action, PTH can stimulate cardiac arrhythmias. PTH was documented as a chronotropic agent able to cause early death ofmyocytes in rat. Importantly, Bogin et al. showed in cultured heart cells of rat, that both amino-terminal PTH 1–34 and intact PTH 1–84 produced an immediate, sustained and significant rise in beats per minute and that the cells died earlier than control cardiomyocytes. Similar bservations were obtained by Shimoyama et al. In human, recent data showed that chronic renal failure and hyperparathyroidism are associated with a sympathetic over-activity. In that case, PTH 1–34 was able to facilitate norepinephrine release in human heart atria by activating the PTH-receptors. Therefore, highly increased PTH levels that can be observed in HF patients can participate to the elevated sympathetic nerve activity and the associated cardiovascular mortality.
The cardiac impact of PTH is also related to calcium overloading in myocardial cells. This cytoplasmic calcium overloading induced by PTH in myocardial cells appears as a paradox for hyperparathyroidism states. The mechanisms behind the increase of intracellular calcium involve a receptor-mediated rise in L-type calcium channel at the plasma membrane level leading to a secondary entry of calcium into cardiomyocyte and mobilization of calcium from sarcoplasmic reticulum. Both PTH 1–34 and PTH 1–84 produced such a dose dependent increase of intracellular calcium in cardiomyocytes. This increase of cytosolic calcium can be prevented by the calcium channel blocker verapamil.
Hyperparathyroidism has also been documented to trigger oxidative stress. When PTH levels are increased, a higher H2O2 production is observed in peripheral blood mononuclear cells. The increase in intracellular calcium induced by PTH might impair the mitochondrial function and ATP production, inducing the production of reactive oxygen species and leading to oxidative stress as well as inflammation and, at the end, to cardiomyocyte necrosis.
Lastly, increased circulating concentrations of PTH might stimulate adrenal aldosterone synthesis, initiating a vicious circle between hyperparathyroidism and hyperaldosteronism and leading to more proinflammatory, pro-oxidant and pro-fibrotic actions.

The rise of PTH in HF
Through its cardiac effects PTH can participate to the pathophysiology of cardiovascular diseases and a chronic excess to high circulating levels of PTH can have some deleterious consequences for the HF patients. Several factors might explain the increase of circulating PTH levels in HF patients.
First of all, impaired cation homeostasis and calcium loss should be considered.   Alteration in electrolyte equilibrium is frequent in HF patients as a consequence of hormonal changes in this pathological condition (hyperadrenergic state and secondary hyperaldosteronism). Calcium wasting is also triggered by diuretics, used to treat HF patients.
A second important factor can be a deficiency of vitamin D. Low vitamin D levels are frequently observed in HF patients and can lead to a rise in PTH levels.
Another documented factor is the interrelationship between hemodynamic state and serum intact PTH levels in patients with HF. Indeed, in a cross-sectional study including 105 patients with chronic HF, log-transformed intact PTH levels were positively and significantly correlated with pulmonary capillary wedge pressure and inversely correlated with stroke volume index after adjusting for variables associated with PTH.

The cross talk between PTH and aldosterone
The cross talk between PTH and FGF-23
Circulating levels of PTH and heart failure
PTH levels in HF patients
PTH testing and heart failure: conclusions and perspectives
PTH testing: assay matters

secondary hyperparathyroidism

secondary hyperparathyroidism

Potential involvement of secondary hyperparathyroidism in the worsening course of heart failure significant correlations were observed, through generation assays, between PTH and natriuretic peptides aswell as galectin-3. Importantly, the different immunoreactivities might impact on the value of PTH testing in treatment and prognosis of HF.

The measurement of PTH concentrations in HF can, like in patients with chronic kidney disease, help to monitor the efficiency of the treatment (drugs as well as medical devices). The use of PTH testing in HF patients might also allow the selection of more personalized and tailored therapies. HF patients with higher PTH levels could be relevant candidates for vitamin D supplementation or other pharmacological treatment. Based on the positive relationship between aldosterone and PTH, higher PTH levels can be an additional reason to use aldosterone blockers in HF patients.

Parathyroid hormone and cardiovascular disease events: A systematic review and meta-analysis of prospective studies

Adriana J. van Ballegooijen, I Reinders, M Visser, and IA Brouwer
Am Heart J 2013;165:655-664.e5
http://dx.doi.org/10.1016/j.ahj.2013.02.014

The parathyroid hormone (PTH) is a key hormone for the maintenance of calcium homeostasis. Low serum calcium triggers the secretion of PTH from the parathyroid glands.1 This results in a raise in serum calcium by promoting the release of calcium from bone, reduces calcium excretion by the kidneys, and increases the calcium absorption by the small intestine. In turn, the increase in calcium inhibits PTH secretion from the parathyroid glands.
In addition to traditionally known target organs, PTH is of interest for its potential impact on cardiovascular disease (CVD) risk. Observational studies have demonstrated that chronic PTH elevation is linked to hypertension, cardiac hypertrophy, and myocardial dysfunction. Furthermore, PTH receptors are present in the myocardium and exert hypertrophic effects on cardiomyocytes. Taken together, these associations suggest plausible mechanisms whereby elevated PTH concentrations may be involved in pathological processes that lead to CVD.

Background Parathyroid hormone (PTH) excess might play a role in cardiovascular health. We therefore conducted a systematic review and meta-analysis to evaluate the association between PTH and cardiovascular disease (CVD) events, and intermediate outcomes.
Methods We conducted a systematic and comprehensive database search using MEDLINE and Embase between 1947 and October 2012. We included English-language prospective studies that reported risk estimates for PTH and CVD events, and intermediate outcomes. The characteristics of study populations, exposure, and outcomes of total CVD events, fatal and non-fatal CVD events were reported, and a quality assessment was conducted. Results were extracted for the highest versus lowest PTH concentrations, and meta-analyses were carried out using random effects models.
Results The systematic literature search yielded 5770 articles, and 15 studies were included. Study duration ranged between 2 and 14 years. All studies were performed primarily in whites with a mean age between 55 and 75 years. The metaanalyses included 12 studies, of which 10 investigated total CVD events; 7, fatal CVD events; and 3, non-fatal CVD events. PTH excess indicated an increased risk for total CVD events: pooled HR (95% CI), 1.45 (1.24-1.71). The results for fatal CVD events and non-fatal CVD events were: HR 1.50 (1.18-1.91) and HR 1.48 (1.14-1.92). Heterogeneity was moderately present; however, sensitivity analyses for follow-up duration, prior CVD, or PTH as dichotomous values showed similar results.
Conclusions The meta-analysis indicates that higher PTH concentrations are associated with increased risk of CVD events.

Impact of estrogen on mechanically stimulated cells in vitro

Jörg Neunzehn, Ulrich Meyer and Hans-Peter Wiesman
Int.J.Curr.Microbiol.App.Sci (2014) 3(5) 898-906
Estrogen deficiency and decreased exercise known to be major causes for osteoporosis in elderly patients are assumed on important role in implant failure. Hormone replacement therapy and exercise are established methods to prevent the accompanying bone loss, thereby improving the conditions for implant osseointegration. Whereas the clinical effects of estrogen on bone are well documented, less is known about estrogen effects on loaded and unloaded osteoblasts on a cellular level. This study was aimed at investigating the effects of estrogen on mechanically stimulated osteoblast like cells in culture. Mechanically unstimulated cultures served as controls. Our investigations revealed that estrogen had a suppressive effect on the proliferative response of osteoblasts towards mechanical strain. Estrogen increased the synthesis of bone specific proteins in mechanically stimulated cultures whereas estrogen had no effect on unstimulated cells. The differentiation effects significant altered at estrogen doses of 10nmol and 10 μmol. Our data suggest a positive effect of hormone substitution on the composition of the extracellular matrix in loaded bones. In the context of implant dentistry, hormone repaints therapy should be regarded as a medical tool to improve the conditions for an undisturbed implant healing.

Normal bone physiology, remodelling and its hormonal regulation

Jennifer S Walsh
Surgery 2014; 33:1

The skeleton has structural and locomotor functions, and is a mineral reservoir. Bone turnover by osteoclasts and osteoblasts is a lifelong process, incorporating growth, modelling and remodeling to repair microdamage and access the mineral reservoir.
Bone formation and resorption are the basis of growth, modeling and remodeling. The bone remodeling cycle is an ongoing process that renews bone to repair microdamage and maintain strength. It also maintains serum calcium in the normal physiological range by release of mineral from the bone matrix as required. About 5-10% of the adult skeleton is replaced by remodeling each year.
On trabecular bone and at the endocortical surface, remodeling takes place on the surface of bone, but within cortical bone the osteoclasts form a cutting cone through the bone matrix. The signal to initiate remodeling may be endocrine (such as increased parathyroid hormone (PTH) in response to hypocalcaemia), which leads to generalized increases in osteoclast activation. Localized remodeling is initiated in response to microdamage, probably by signals from osteocytes. During a remodeling cycle, osteoclasts on the bone surface become activated and resorb bone matrix, creating a defect which is filled in by osteoblasts. The cycle usually takes about 200 days to complete. The bone remodeling cycle is highly regulated, and resorption and formation are closely coupled.
Signaling between bone cells is essential for the coordination of these processes. Osteoblasts regulate osteoclast activity through the receptor activator of nuclear factor-kB (RANK)/RANK ligand/osteoprotegerin system, and osteocytes regulate osteoblast activity through sclerostin secretion. If resorption and formation are balanced there is no net change in bone mass after each cycle, but with ageing and some disease states resorption exceeds formation leading to remodeling imbalance, decreased bone mass and loss of microstructural integrity. The rate of remodeling is determined by loading and endocrine influences. The most important endocrine regulator of bone turnover is probably estrogen, but other hormones regulating bone metabolism include insulin-like growth factor-1, parathyroid hormone and gut and adipocyte hormones.

Differential Diagnosis, Causes, and Management of Hypercalcemia

Fredriech K. W. Chan, et al.
Current Problems In Surgery June 1997; 34(6)

Hypercalcemia is a challenging clinical syndrome, both in diagnosis and therapy. The two most common causes of hypercalcemia, primary hyperparathyroidism and malignancy, account for approximately 90% of all patients with an elevated calcium level. In the general population, primary hyperparathyroidism is more common than malignancy. In a hospitalized population, malignancy is by far the more common. The differential diagnosis of hypercalcemia should be focused initially on the distinction between primary hyperparathyroidism and malignancy.

Primary hyperparathyroidism is caused by excessive, abnormally regulated secretion of parathyroid hormone from one or more adenomatous or hyperplastic parathyroid glands. In 80% of cases, primary hyperparathyroidism is due to a single adenoma. In 15% to 20% of patients, all four glands are enlarged as a result of hyperplasia. Parathyroid hyperplasia is also encountered in patients with Multiple Endocrine Neoplasia, Type I or II. Rarely, in fewer than 0.5% of patients, primary hyperparathyroidism is due to parathyroid carcinoma. The clinical features of primary hyperparathyroidism result from the hypercalcemia and the excessive output of parathyroid hormone (PTH).
The major target organs are the bones and the kidneys. The classic but rare bone disease of primary hyperparathyroidism is osteitis fibrosa cystica. Since the advent of the multichannel autoanalyzer in the early 1970s, an era marked by a great increase in incidence of primary hyperparathyroidism, the prevalence of radiologically apparent bone disease in patients with primary hyperparathyroidism has declined from 10% to 15% to a vanishingly small 1% to 2%. Sensitive technologies such as bone densitometry and bone histomorphometry, however, have revealed skeletal involvement with preferential reduction of cortical bone mass and relative preservation of cancellous bone mass. Although the incidence of nephrolithiasis in primary hyperparathyroidism has also decreased markedly, from approximately 60% in the 1940s and 1950s to 15% to 20% now, nephrolithiasis is still the most frequent complication of primary hyperparathyroidism.
Primary hyperparathyroidism also can be associated with neuropsychiatric, gastrointestinal, and cardiovascular manifestations. However, evidence that these features are pathophysiologically linked to the hyperparathyroid process or are reversible after successful parathyroidectomy is not compelling.

Management of Skeletal Health in Patients With Asymptomatic Primary Hyperparathyroidism

  1. Michael Lewiecki
    J Clin Densitometry: Assessment of Skeletal Health, 2010; 13(4), 324e334.
    http://dx.doi.org:/10.1016/j.jocd.2010.06.004

Asymptomatic primary hyperparathyroidism (PHPT) may cause adverse skeletal effects that include high bone remodeling, reduced bone mineral density (BMD), and increased fracture risk. Parathyroid surgery, the definitive treatment for PHPT, has been shown to increase BMD and appears to reduce fracture risk. Current guidelines recommend parathyroid surgery for patients with symptomatic PHPT or asymptomatic PHPT with serum calcium > 1 mg/dL above the upper limit of normal, calculated creatinine clearance < 60 mL/min, osteoporosis, previous fracture, or age > 50 yr. The type of operation performed (parathyroid exploration or minimally invasive procedure) and localizing studies to identify the abnormal parathyroid glands preoperatively should be individualized according to the skills of the surgeon and the resources of the institution. In patients who choose not to be treated surgically or who have contraindications for surgery, medical therapy should include a daily calcium intake of at least 1200 mg and maintenance of serum 25-hydroxyvitamin D levels of at least 20 ng/mL (50 nmol/L). Bisphosphonates and estrogens have been shown to provide skeletal benefits that appear to be similar to parathyroid surgery. Cinacalcet reduces serum calcium in PHPT patients with intractable hypercalcemia but has not been shown to improve BMD. It is not known whether any medical intervention reduces fracture risk in patients with PHPT. There are insufficient data on the natural history and treatment of normocalcemic PHPT to make recommendations for management of this disorder.

Hyperparathyroidism

William D Fraser
thelancet July 11, 2009; 374: 145-158 – Seminar

Hyperparathyroidism is due to increased activity of the parathyroid glands, either from an intrinsic abnormal change altering excretion of parathyroid hormone (primary or tertiary hyperparathyroidism) or from an extrinsic abnormal change affecting calcium homoeostasis stimulating production of parathyroid hormone (secondary hyperparathyroidism). Primary hyperparathyroidism is the third most common endocrine disorder, with the highest incidence in postmenopausal women. Asymptomatic disease is common, and severe disease with renal stones and metabolic bone disease arises less frequently now than it did 20–30 years ago. Primary hyperparathyroidism can be cured by surgical removal of an adenoma, increasingly by minimally invasive parathyroidectomy. Medical management of mild disease is possible with bisphosphonates, hormone replacement therapy, and calcimimetics. Vitamin D deficiency is a common cause of secondary hyperparathyroidism, particularly in elderly people. However, the biochemical definition of vitamin D deficiency and its treatment are subject to much debate. Secondary hyperparathyroidism as the result of chronic kidney disease is important in the genesis of renal bone disease, and several new treatments could help achieve the guidelines set out by the kidney disease outcomes quality initiative.

Table 1: Changing clinical presentation of primary hyperparathyroidism
1930–1970 1970–2000
Nephrolithiasis 51–57% 17–37%
Hypercalciuria 36% 40%
Overt skeletal disease 10–23% 4–14%
Asymptomatic 6–18% 22–80%
Modified from reference 12
Panel 1: Recommendations for surgery from the National Institutes of Health
consensus conference on primary hyperparathyroidism in 1990 and 2002• Serum albumin-adjusted calcium greater than 0·25 mmol/L
above the upper limit of local laboratory reference range

• Urine calcium greater than 10 mmol per 24 h

• Creatinine clearance reduced by 30% or more

• Bone mineral density T score less than –2·5 (at any site)

• Age younger than 50 years

• Patient request; adequate follow-up unlikely

Aldosterone and parathyroid hormone interactions as mediators of metabolic and cardiovascular disease

Andreas Tomaschitz, Eberhard Ritz, Burkert Pieske, Jutta Rus-Machan
Metabolism Clinical and  Experimental 2014; 63: 20 31
http://dx.doi.org/10.1016/j.metabol.2013.08.016

Several studies demonstrated a strong link between dysregulation of the aldosterone and parathyroid hormone (PTH) axes on the one hand and CV pathology on the other hand. Such evidence documents clinically relevant interactions between aldosterone and PTH and a resulting impact on CV health. This review provides an up to date overview discussing the mechanisms and the clinical relevance underlying the interactions between aldosterone and PTH.

Inappropriate aldosterone and parathyroid hormone (PTH) secretion is strongly linked with development and progression of cardiovascular (CV) disease. Accumulating evidence suggests a bidirectional interplay between parathyroid hormone and aldosterone. This interaction may lead to a disproportionally increased risk of CV damage, metabolic and bone diseases.

This review focuses on mechanisms underlying the mutual interplay between aldosterone and PTH as well as their potential impact on CV, metabolic and bone health. PTH stimulates aldosterone secretion by increasing the calcium concentration in the cells of the adrenal zona glomerulosa as a result of binding to the PTH/PTH-rP receptor and indirectly by potentiating angiotensin 2 induced effects. This may explain why after parathyroidectomy lower aldosterone levels are seen in parallel with improved cardiovascular outcomes.

Aldosterone mediated effects are inappropriately pronounced in conditions such as chronic heart failure, excess dietary salt intake (relative aldosterone excess) and primary aldosteronism.

PTH is increased as a result of
(1) the MR (mineralocorticoid receptor)mediated calciuretic and magnesiuretic effects with a trend of hypocalcemia and hypomagnesemia; the resulting secondary hyperparathyroidism causes myocardial fibrosis and disturbed bone metabolism; and

(2) direct effects of aldosterone on parathyroid cells via binding to the MR. This adverse sequence is interrupted by mineralocorticoid receptor blockade and adrenalectomy.

Hyperaldosteronism due to klotho deficiency results in vascular calcification, which can be mitigated by spironolactone treatment. In view of the documented reciprocal interaction between aldosterone and PTH as well as the potentially ensuing target organ damage, studies are needed to evaluate diagnostic and therapeutic strategies to address this increasingly recognized pathophysiological phenomenon.

The classical view that aldosterone acts exclusively on the electrolyte transport in epithelial cells has been broadened after the mineralocorticoid receptor (MR) has been identified in non-epithelial cells as well, e.g. vascular smooth muscle cells and cardiomyocytes. Apart from classical genomic effects, non-genomic aldosterone mediated effects have been identified in various tissues and organs outside of the kidneys and colon, e.g. inner ear, choroid plexus, endothelial cells and cardiomyocytes.

In the past it had been documented that primary aldosteronism (PA; absolute aldosterone excess) contributed to the development of CVD. Several studies suggested, however, that “absolute aldosterone excess” is only the tip of the iceberg leading to the concept of “relative aldosterone excess” . Several large cross-sectional and prospective studies demonstrated a consistent relationship between circulating aldosterone levels, CV risk factors and mortality risk.

Such recent studies also document that even circulating aldosterone concentrations in the “normal” range may result in inappropriate aldosterone–MR interaction which may be reversed by MR blockade.
The identification of PTH receptors within the CV system e.g. in cardiomyocytes, vascular smooth muscle, and endothelial cells, indicates that inappropriate PTH secretion may impact on the CV health beyond the dysregulation of calcium and phosphate homeostasis.

Application of PTH after myocardial infarction attenuates ischaemic cardiomyopathy by increasing migration of bone marrow-derived stem cells to the ischaemic myocardium. On the other hand the PTH excess in primary hyperparathyroidism (pHPT) is linked in the long-term to a spectrum of adverse effects e.g. bone loss and increased fracture risk, coronary microvascular dysfunction, derangement of lipid and glucose metabolism, subclinical aortic valve calcification, increased aortic stiffness, endothelial dysfunction and arterial hypertension.

Interactions between vitamin D, klotho and aldosterone
Increased activity of systemic or local renin–angiotensin systems (RAS) is linked to increased target organ damage. The organ and tissue protective effects of vitamin D have in part been explained by vitamin D induced modulation of RAS activity.

In landmark experiments Li et al. documented markedly elevated renin mRNA expression in the juxtaglomerular apparatus of vitamin D receptor (VDR) knock-out mice compared to wild type mice. Furthermore, 1,25-dihydroxy vitamin D (1,25(OH2)D3) modulated renin gene transcription and renin synthesis and this was independent of serum calcium, PTH and angiotensin 2. Angiotensin 2 in turn reduces renal klotho expression resulting in modulations of FGF-23-signaling and of 1-α hydroxylase activity. Klotho is a membrane (and circulating) protein which is highly expressed in the kidney and modulates the inhibitory effects of FGF-23 on calcitriol formation; klotho contributes to the regulation of renal tubular calcium and phosphate reabsorption. The modulatory effects of vitamin D on the RAS might result in a lower risk of development and progression of CV morbidity and mortality.

Evidence for stimulating effects of PTH on adrenal aldosterone secretion Aldosterone synthesis is mainly initiated by angiotensin 2 and potassium via activating the Ca2+-messenger system in zona glomerulosa (ZG) cells to stimulate the steroidogenic cascade within the mitochondria. The Ca2+-messenger system further participates in the initiation of steroidogenesis by facilitating the cholesterol transfer into the mitochondria. Findings from experimental, mechanistic, observational and interventional studies suggest that PTH contributes to the regulation of aldosterone secretion in the ZG of the adrenal glands.

The interaction between aldosterone and Klotho and its relationship to vascular osteoinduction

The interaction between aldosterone and Klotho and its relationship to vascular osteoinduction

The interaction between aldosterone and Klotho and its relationship to vascular osteoinduction

Estradiol determines the effects of PTH on ERa-dependent transcription in MC3T3-E1 cells

Monika H.E. Christensen, IS Fenne, MH Flågeng, B Almås, et al.
Biochemical and Biophysical Research Communications 450 (2014) 360–365
http://dx.doi.org/10.1016/j.bbrc.2014.05.109

Bone remodeling is a continuous process regulated by several hormones such as estrogens and parathyroid hormone (PTH). Here we investigated the influence of PTH on estrogen receptor alpha (ERa)-dependent transcriptional activity in MC3T3-E1 osteoblasts. Cells that were transfected with an ER-responsive reporter plasmid and treated with PTH showed increased luciferase activity. However, in the presence of 17b-estradiol, we observed that PTH inhibited ERa-mediated transcription. cAMP mimicked the effects by PTH, and the findings were confirmed in COS-1 cells transfected with expression vector encoding the catalytic subunit of cAMP-dependent protein kinase (PKA). Furthermore, PTH exhibited specific effects on the mRNA expression of the decoy receptor osteoprotegerin (OPG) and the receptor activator of NF kappa-B ligand (RANKL) in MC3T3-E1 osteoblasts. In the absence of 17b-estradiol, PTH and cAMP enhanced the OPG/RANKL ratio, whereas, OPG/RANKL was suppressed when estradiol was present. In conclusion, our results indicate that the presence of estradiol determines whether PTH and cAMP stimulates or inhibits ERa-dependent activity and the OPG/RANKL mRNA expression in an osteoblastic cell line.

Ginsenoside-Rb2 displays anti-osteoporosis effects through reducing oxidative damage and bone-resorbing cytokines during osteogenesis

Qiang Huang, Bo Gao, Qiang Jie, Bo-Yuan Wei, et al.
Bone 66 (2014) 306–314
http://dx.doi.org/10.1016/j.bone.2014.06.010

Reactive oxygen species (ROS) are a significant pathogenic factor of osteoporosis. Ginsenoside-Rb2 (Rb2), a 20(S)-protopanaxadiol glycoside extracted from ginseng, is a potent antioxidant that generates interest regarding the bone metabolism area. We tested the potential anti-osteoporosis effects of Rb2 and its underlying mechanism in this study. We produced an oxidative damage model induced by hydrogen peroxide (H2O2) in osteoblastic MC3T3-E1 cells to test the essential anti-osteoporosis effects of Rb2 in vitro. The results indicated that treatment of 0.1 to 10 μMRb2 promoted the proliferation of MC3T3-E1 cells, improved alkaline phosphatase (ALP) expression, elevated calcium mineralization and mRNA expressions of Alp, Col1a1, osteocalcin (Ocn) and osteopontin (Opn) against oxidative damage induced by H2O2. Importantly, Rb2 reduced the expression levels of receptor activator of nuclear factor kappa-B ligand (RANKL) and IL-6 and inhibited the H2O2-induced production of ROS. The in vivo study indicated that the Rb2 administered for 12 weeks partially decreased blood malondialdehyde (MDA) activity and elevated the activity of reduced glutathione (GSH) in ovariectomized (OVX)mice. Moreover, Rb2 improved the micro-architecture of trabecular bones and increased bone mineral density (BMD) of the 4th lumbar vertebrae (L4) and the distal femur. Altogether, these results demonstrated that the potential anti-osteoporosis effects of Rb2 were linked to a reduction of oxidative damage and bone-resorbing cytokines, which suggests that Rb2 might be effective in preventing and alleviating osteoporosis.

Inflammatory cytokines in Paget’s disease of bone

GRW de Castro, Z Buss, JS Da Rosa, TS Fröde
International Immunopharmacology 18 (2014) 277–281
http://dx.doi.org/10.1016/j.intimp.2013.12.003

This study was undertaken to evaluate the expression of inflammatory cytokines in patients with Paget’s disease of bone (PDB). Serum levels of tumoral necrosis factor-α, interleukin 1β, interleukin-6 and interleukin-17
were measured in 51 patients with PDB and in 24 controls with primary osteoarthritis. Compared to controls, patients with Paget’s disease of bone presented higher levels of interleukin 6 and reduced interleukin 17, but levels of tumoral necrosis factor α and interleukin 1 β did not differ significantly. We found no significant differences when patients were compared according to disease activity or current treatment. There were no correlations between cytokine levels and bone-specific alkaline phosphatase or extension of Paget’s disease of bone on bone scintigraphs. In conclusion, patients with PDB present significant differences on levels of certain cytokines in comparison to primary osteoarthritis patients, but these alterations did not appear to have a clear correlation with parameters of disease activity or severity.

Development and validation of a novel cell-based assay for potency determination of human parathyroid hormone (PTH)
Axel Hohenstein, Meike Hebell, Heidi Zikry, Maria El Ghazaly, et al.
Journal of Pharmaceutical and Biomedical Analysis 98 (2014) 345–350
http://dx.doi.org/10.1016/j.jpba.2014.06.004

Disorders of bone metabolism
Orthopaedics I: General Principles

Nicola Peel
Surgery 33:1

Bone remodeling is critical to bone health. Alterations in the normal processes and regulation of remodeling may impact on bone mass and bone strength. Changes may be generalized or focal and underlie many of the common disorders of bone metabolism. This article focuses on the changes in bone remodeling which underlie both the development and treatment of osteoporosis. Osteomalacia, as an example of a mineralization disorder and Paget’s disease as an example of a focal disorder of bone remodeling, are also briefly reviewed.

There are many causes of increased bone turnover with the most common being the loss of estrogen at menopause. Increased bone turnover is initiated by increased activation frequency of osteoclasts. The consequent increase in remodeling space leads to bone loss which is, at least in part, reversible. Increased bone turnover is also associated with an increased risk of trabecular perforation with the increased number of remodeling sites acting as stress risers within the trabecular architecture. Bone loss within the trabecular compartment occurs preferentially from the horizontal, non-weight bearing plates resulting in disproportionate loss of bone strength for the reduction in bone mass.
Alterations in bone turnover also have potential to affect bone.

strength by changing the degree of mineralization. Primary mineral apposition occurs early after production of bone matrix by osteoblasts. After completion of the cycle, secondary mineral apposition occurs over many months. Increased bone turnover leads to reduced mineralization as the time between remodeling cycles reduces. Conversely, decreased bone turnover rates reduce the average time between remodeling at any site and hence lead to a greater degree of mineralization. Biomechanical principles indicate that the yield strength (stiffness) of highly mineralized bone increases but that it will withstand less deformation before fracture and therefore becomes brittle. A reduced degree of mineralization results in greater pliability but a reduction in bone strength.
Alterations in bone remodeling underpin changes in bone mass and bone strength. The impact of these changes is manifest in the development and clinical presentation of osteoporosis.

Paget’s disease

Paget’s disease

Paget’s disease: (a) increased uptake on nuclear medicine scanning in the right hemipelvis, sacrum and left femur and (b) left femur showing radiological changes of Paget’s including a fissure fracture in the proximal lateral cortex

Paget’s disease is an example of a localised disorder of bone turnover. Its aetiology remains unclear. Paget’s disease is not uncommon but is often asymptomatic and diagnosed coincidentally. It is estimated to affect approximately 2% of adults over the age of 55 in the UK but the prevalence varies markedly between populations. It is increasingly prevalent with increasing age and affects men more frequently than women. In 80% of cases more than one bone is involved, characteristically in an asymmetric distribution.
Pagetic bone is characterized by the presence of giant multinucleated osteoclasts resulting in dramatic increases in bone resorption in the affected bones. These regions undergo a lytic phase followed by a compensatory increase in bone formation. Rapid bone formation results in an accumulation of woven bone, which is mechanically abnormal resulting in loss of bone strength.
The typical clinical manifestation is of bone pain, which may be associated with bone expansion and deformity. Complications of Paget’s disease include the development of secondary osteoarthritis, fissure fractures and very rarely, osteosarcomatous change (<1% of cases).

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