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Archive for the ‘Lipidomics’ Category


 Cholesterol Lowering Novel PCSK9 drugs: Praluent [Sanofi and Regeneron] vs Repatha [Amgen] – which drug cuts CV risks enough to make it cost-effective?

Reporter: Aviva Lev-Ari, PhD, RN

 

Did Amgen’s Repatha cut CV risks enough to make it cost-effective? Analysts say no

Sanofi, Regeneron’s Praluent pulls off PCSK9 coup with 29% cut to death risks in most vulnerable patients
SEE our curations on PCSK9 drugs:
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ODYSSEY Outcomes trial evaluating the effects of a PCSK9 inhibitor, alirocumab, on major cardiovascular events in patients with an acute coronary syndrome to be presented at the American College of Cardiology meeting on March 10.

Reporter: Aviva Lev-Ari, PhD, RN

 

For PCSK9 inhibitors, the effect on major adverse cardiovascular events has always fallen short of expectations based on cholesterol lowering.

But cardiovascular risk reduction is complicated. There is more to the puzzle than cholesterol. Some drugs lower both cholesterol and prevent cardiovascular events, but some people think that the two effects are actually not that closely related.

Milton Packer MD

https://www.medpagetoday.com/blogs/revolutionandrevelation/71435

In a previous trial (FOURIER), another PCSK9 inhibitor had only a modest benefit on its primary endpoint, and it did not reduce cardiovascular death, although the magnitude of cholesterol lowering was striking.

In another trial (SPIRE), a third PCSK9 inhibitor, the clinical trial was terminated prematurely by Pfizer because of reduction of the effect of the drug (a humanized but not fully humanized antibody) due to development of neutralizing antibodies in some of the patients. Actually, in patients treated for more than a year who did not develop neutralizing antibodies, a beneficial effect was seen.

The ODYSSEY Outcomes trial is evaluating the effects of a PCSK9 inhibitor,alirocumab, on major cardiovascular events in patients with an acute coronary syndrome within the prior year. The drug lowers serum cholesterol dramatically, and some are hopeful that that effect will translate into an important reduction in the risk of major adverse cardiovascular events. If you believe that cholesterol reduction inevitably leads to the prevention of cardiovascular death, myocardial infarction and stroke, then you would have high expectations for the ODYSSEY trial.

ODYSSEY. The trial uses a somewhat more aggressive treatment strategy and has a longer follow-up period than its predecessors. So maybe the benefit will be large. Maybe the drug will even reduce cardiovascular death or all-cause mortality.

In order to enrich the population for cardiovascular events, the trial enrolled patients with an acute coronary syndrome within the prior year. These patients are at high risk of having a recurrence. The problem is that risk is not necessarily related to changes in cholesterol, especially the events occurring early in the trial. And in this type of trial, the analysis tends to give extra weight to early events.

Trials like ODYSSEY are often designed to stop early if the results are unbelievably impressive. The ODYSSEY trial wasn’t stopped early.

the patients entering the ODYSSEY trial are starting out with a serum LDL <100 mg/dL or even <90 mg/dL. Is cholesterol really playing an important role at that level, especially when compared with noncholesterol factors?

SOURCE

https://www.medpagetoday.com/blogs/revolutionandrevelation/71435

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  1. Lungs can supply blood stem cells and also produce platelets: Lungs, known primarily for breathing, play a previously unrecognized role in blood production, with more than half of the platelets in a mouse’s circulation produced there. Furthermore, a previously unknown pool of blood stem cells has been identified that is capable of restoring blood production when bone marrow stem cells are depleted.

 

  1. A new drug for multiple sclerosis: A new multiple sclerosis (MS) drug, which grew out of the work of UCSF (University of California, San Francisco) neurologist was approved by the FDA. Ocrelizumab, the first drug to reflect current scientific understanding of MS, was approved to treat both relapsing-remitting MS and primary progressive MS.

 

  1. Marijuana legalized – research needed on therapeutic possibilities and negative effects: Recreational marijuana will be legal in California starting in January, and that has brought a renewed urgency to seek out more information on the drug’s health effects, both positive and negative. UCSF scientists recognize marijuana’s contradictory status: the drug has proven therapeutic uses, but it can also lead to tremendous public health problems.

 

  1. Source of autism discovered: In a finding that could help unlock the fundamental mysteries about how events early in brain development lead to autism, researchers traced how distinct sets of genetic defects in a single neuronal protein can lead to either epilepsy in infancy or to autism spectrum disorders in predictable ways.

 

  1. Protein found in diet responsible for inflammation in brain: Ketogenic diets, characterized by extreme low-carbohydrate, high-fat regimens are known to benefit people with epilepsy and other neurological illnesses by lowering inflammation in the brain. UCSF researchers discovered the previously undiscovered mechanism by which a low-carbohydrate diet reduces inflammation in the brain. Importantly, the team identified a pivotal protein that links the diet to inflammatory genes, which, if blocked, could mirror the anti-inflammatory effects of ketogenic diets.

 

  1. Learning and memory failure due to brain injury is now restorable by drug: In a finding that holds promise for treating people with traumatic brain injury, an experimental drug, ISRIB (integrated stress response inhibitor), completely reversed severe learning and memory impairments caused by traumatic brain injury in mice. The groundbreaking finding revealed that the drug fully restored the ability to learn and remember in the brain-injured mice even when the animals were initially treated as long as a month after injury.

 

  1. Regulatory T cells induce stem cells for promoting hair growth: In a finding that could impact baldness, researchers found that regulatory T cells, a type of immune cell generally associated with controlling inflammation, directly trigger stem cells in the skin to promote healthy hair growth. An experiment with mice revealed that without these immune cells as partners, stem cells cannot regenerate hair follicles, leading to baldness.

 

  1. More intake of good fat is also bad: Liberal consumption of good fat (monounsaturated fat) – found in olive oil and avocados – may lead to fatty liver disease, a risk factor for metabolic disorders like type 2 diabetes and hypertension. Eating the fat in combination with high starch content was found to cause the most severe fatty liver disease in mice.

 

  1. Chemical toxicity in almost every daily use products: Unregulated chemicals are increasingly prevalent in products people use every day, and that rise matches a concurrent rise in health conditions like cancers and childhood diseases, Thus, researcher in UCSF is working to understand the environment’s role – including exposure to chemicals – in health conditions.

 

  1. Cytomegalovirus found as common factor for diabetes and heart disease in young women: Cytomegalovirus is associated with risk factors for type 2 diabetes and heart disease in women younger than 50. Women of normal weight who were infected with the typically asymptomatic cytomegalovirus, or CMV, were more likely to have metabolic syndrome. Surprisingly, the reverse was found in those with extreme obesity.

 

References:

 

https://www.ucsf.edu/news/2017/12/409241/most-popular-science-stories-2017

 

https://www.ucsf.edu/news/2017/03/406111/surprising-new-role-lungs-making-blood

 

https://www.ucsf.edu/news/2017/03/406296/new-multiple-sclerosis-drug-ocrelizumab-could-halt-disease

 

https://www.ucsf.edu/news/2017/06/407351/dazed-and-confused-marijuana-legalization-raises-need-more-research

 

https://www.ucsf.edu/news/2017/01/405631/autism-researchers-discover-genetic-rosetta-stone

 

https://www.ucsf.edu/news/2017/09/408366/how-ketogenic-diets-curb-inflammation-brain

 

https://www.ucsf.edu/news/2017/07/407656/drug-reverses-memory-failure-caused-traumatic-brain-injury

 

https://www.ucsf.edu/news/2017/05/407121/new-hair-growth-mechanism-discovered

 

https://www.ucsf.edu/news/2017/06/407536/go-easy-avocado-toast-good-fat-can-still-be-bad-you-research-shows

 

https://www.ucsf.edu/news/2017/06/407416/toxic-exposure-chemicals-are-our-water-food-air-and-furniture

 

https://www.ucsf.edu/news/2017/02/405871/common-virus-tied-diabetes-heart-disease-women-under-50

 

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LIVE 9/21 8AM to 2:40PM Targeting Cardio-Metabolic Diseases: A focus on Liver Fibrosis and NASH Targets at CHI’s 14th Discovery On Target, 9/19 – 9/22/2016, Westin Boston Waterfront, Boston

http://www.discoveryontarget.com/

http://www.discoveryontarget.com/crispr-therapies/

#BostonDOT16

@BostonDOT

 

Nonalcoholic Steatohepatitis (NASH)

 

Leaders in Pharmaceutical Business Intelligence (LPBI) Group is a

Media Partner of CHI for CHI’s 14th Annual Discovery on Target taking place September 19 – 22, 2016 in Boston.

In Attendance, streaming LIVE using Social Media

Aviva Lev-Ari, PhD, RN

Editor-in-Chief

http://pharmaceuticalintelligence.com

 

Wednesday, September 21

7:30 am Registration Open and Morning Coffee

8:00 Chairperson’s Opening Remarks

Rebecca Taub, M.D., Ph.D., CEO, Madrigal Pharmaceuticals

  • Epidemic of NASH,
  • approaches to treating NASH – Fibrosis
  • NASH is a metabolic Disease of the Liver
  • Treating the HCV will treat the Fibrosis

8:10 FEATURED PRESENTATION: The Epidemic of Fatty Liver Disease: Silent, Serious and Still Growing?

Lee Kaplan, M.D., Ph.D., Director, Obesity, Metabolism and Nutrition Institute, Massachusetts General Hospital, Harvard Medical School

  • Silent, Serious and Growing
  • Obesity the Disease = BMI>30: Medical Complicastions for BMI >%) – On ANti-Obisity and Bariatric SUrgery, Type 2 Diabetis .. NAFLD .. NASH .. Cirrhosis .. HCC
  • Parkinson’s Disease
  • HIV/AIDS
  1. Medical Complications of Obisity =197 :
  2. NAFLD – Nonalcoholic Fatty Liver Disease >>> Liver transplantation replacing HCV
  3. Associated with obesity and type 2 diabetes
  4. NAFLD is UP 90% wiht Severe Obesity
  5. Viral hepatitis and Hemochromatosis
  6. NAFLD: Steatosis, Inflamamtion, Hepatocellular Necrosis, Fibrosis, Cirrhosis
  7. NASH: insulin resistence .. metabolic syndrom .. interaction
  8. Alternative Model: Metabolis Syndrom.. Steatosis .. NASH … FIbrosis
  9. Genetics of Liver DIsease
  10. PNPLA3 Associated with NAFLD – Not Weight Gain
  11. Other genes: A Partial List:
  12. Diagnosis of NASH: Liver biopsy macrovescicular fatty change: InflammationMollery bodies
  13. 75% Patients with Cirrhousis have obisity
  14. Alcoholoc hepatisis >> Progression to Cirrhousis
  15. Macrovesicular Steatosis
  16. NASH – inflammation
  17. Sinusoidal Pericellular Fibrosis –
  18. LAB Features of NAFLD
  • Transaminase elevation
  • Akaline phosphate
  1. Biomarkers – NASH – associated cirrhousis with lower rate 30% of elevation
  2. Fibrosure
  • Clinical Features of NASH: none presentation, Bright, Echo Fibroscan FibroscanScreen for HCC, Varices if Gray zone: Biopsy
  • Treatment of NASH
  • Treat liver disease: Treat steatosis then Inflamamtion and fibrosis
  1. NAFLD Treatment Strategy: Stepwise Approach
  • Treat the steatosis Piodlitazone
  • PPARalpha, delta,
  • Treat Inflammation: ANtioxidant
  • CCR2/CCR% inhibitors
  • Metabolic SUrgery
  • Weigh-independent for bariatric
  • Bariatic: improvrment of steatosis,effect on inflammationless clear
  • dramatic on weigh loss
  • NO clear is surgery improved cirhousis
  • If NASH developed >>>> progression s the rule
  • No great treatment of NASH

Medication-assciated NASH: Glucocorti

 

8:40 Non-Alcoholic Steatohepatitis and Cardiovascular Disease: Modulation by Novel PPAR Agonists

Bart Staels, Ph.D., Professor, INSERM, University of Lille, Pasteur Institute

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors which regulate lipid and glucose metabolism as well as inflammation. In this presentation, we will review recent findings on the pathophysiological role of PPARs in the different stages of non-alcoholic fatty liver disease (NAFLD), from steatosis development to steatohepatitis and fibrosis, as well as the preclinical and clinical evidences for potential therapeutical use of PPAR agonists in the treatment of NAFLD. PPARs play a role in modulating hepatic triglyceride accumulation, a hallmark of the development of NAFLD. Moreover, PPARs may also influence the evolution of reversible steatosis towards irreversible, more advanced lesions. Large controlled trials of long duration to assess the long-term clinical benefits of PPAR agonists in humans are ongoing.

Non-Alcoholic Steatohepatisis and CVD – Meta inflammatory disease

  • NAFL — abnormal Lipid accumulation
  • NASH >> Balooning, FIbrosis inflamation
  • Resolution of NASH is associated with reduction of Fibrosis (Golden – 505 trial)

CVD is linked to NAFLD: Lipids elevated and therosclerosis

  • TG – elevated, APO B elevated, VLDL – elevated HDL decrease
  • PPAR Alpha
  • Gamma
  • PPAR Beta/Delta agonist: GENFIT – Elafibranor
  • SPPARM

Trans-activation: Lipid and Glucose homeostasis: Trans-repression – anti-inflammatory properties

  • Hapatic mitochondrial activity deseases upon progression from NAFL to NASH: Obese NAFL and NASH
  1. Upregulated hepatic respiratory in obese humans with or without NAFL
  2. Impaired
  3. Hepatic PPARalpha Expression Decreases upon Progression of Nash and Fibrosis
  4. hepatic PPARalpha expression – target genes increase in patients with improved NASH histology after 1 year
  5. Metabolic Regualtion by thehepatic JNK Signaling Pathway
  6. Target gene transcription – miR-21 expression increases in human
  7. PPAR Delta: Elafibbranor: – effect on plasma lipids: A Dual PPAR alpha/Delts (GFT505): 80mg vs placebo and 120mg vs placebo, improves plasma apolipolipids and glucose HbA1C – insulin sensitivity
  8. efficacy in NASH acting on: Steatosis, fibrosis and cirrhosis
  9. inflammatory markers: RESOLVE-IT Phase 3 Study Desing: NASH ressolution without adverse on FIbrosis and Cirrhosis

GOLDEN505 Trial: Improves plasma lipid levels: Triglycerides

Inclusion Criteria:

ALT, AST, GGT, ALP

Improve atherogenic dyslipidemia

  • APOC3 – associated with CVD

9:10 PANEL DISCUSSION: Liver Fibrosis and NASH Targets

Moderator: H. James Harwood, Ph.D., Delphi BioMedical Consultants, LLC

Panelists:

Lee Kaplan, M.D., Ph.D., Director, Obesity, Metabolism and Nutrition Institute, Massachusetts General Hospital, Harvard Medical School

Bart Staels, Ph.D., Professor, INSERM, University of Lille, Pasteur Institute

Rebecca Taub, M.D., Ph.D., CEO, Madrigal Pharmaceuticals

Weilin Xie, Ph.D., Senior Principal Scientist, Biotherapeutics, Celgene Corp.

  • FDA’s view on surrogate endpoints
  • Biomarkers of NASH
  • Regulatory challenges
  1. Liver biopsy: gold standard, invasive direct measure of endpoints pros/cons
  2. non-invasive functional tests – plasma bioamrkers
  3. non-invasisve liver imaging techniques: MRI to assess hepatic fat content MRE to assess hepatic fibrosis, Fibroscan,
  4. Endpoints acceptable by FDA: Current vs Future
  • Pre clinical Translational animal models

Discussion by Panel members

Progression from NAFLD to NASH: Oxidative stress and toxic lipids

NASH and Steatosis are different populations

Alcoholoc Steatosis vs Non-Alcoholic Steatosis

  • Obesity cause of Fatty liver
  • NASH in Diabetes
  • NASH progresses
  • Steatosis is associated with NASH
  • Different types of NASH: HTN, Dislipedemia,
  • GENETICS underlining factors, more genes are discovered
  • Limitations of Animal Studies for inference on Humans – careful in over generalizing results
  • Metabolic SYndrom -not all progresses to NASH
  • Nonalcoholic Steatohepatitis (NASH) depend on Steatosis

 

9:40 Coffee Break in the Exhibit Hall with Poster Viewing

10:25 Targeting Fibroblast Activation Protein (FAP) and FGF21 to Treat Fatty Liver Disease

Diana Ronai Dunshee, Ph.D., Department of Molecular Biology, Senior Scientific Researcher, Genentech, Inc.

FGF21 is a hormone with anti-obesity and hepatoprotective properties. However, the beneficial effects of FGF21 are limited by a relatively short half-life in circulation. We discovered that fibroblast activation protein (FAP), an endopeptidase overexpressed in liver with cirrhosis, cleaves and inactivates FGF21. Pharmacological inhibition of FAP increases endogenous levels of active FGF21, thus making FAP a promising target for the treatment of non-alcoholic-steatohepatitis (NASH).

  • Medical complications of obisity: NASH and DM-2
  • energy consumption
  • white adipose tissue – energy storage
  • brown adipose tissue matochondia’s energy
  • FGF21 – Human activation of protein cleavage: A Homone beneficial on metabolic health circulation, weigh loss
  • it suppreses hepatic Steatohepatitis
  • One singleinjection in mice — leads to energy expenditure induced weigh loss and metabolic improvement in Obese Humans
  • Negative FGF21 is Rapidly Eliminated from the body – renal degradation and Inactivation of FGF21 Endopeptidase Cleavage Site – Fibroblast Activation Protein Matched FAP Endopeptidease Specificity
  • Closest relative of DPP4 upregulted during tissue injury in NASH
  • FAP is SUfficient to Cleave FGF21
  • Recombinant FGF21 with Recombinant FAP in Serum or Plasma
  • FAP Protease – Serum Immunodepleted Ablates FGF21 Cleavage Activity: Peptide IgG vs anti-FAP
  • FAP Cleavage Inactivates Human FGF21 dependent on KLB-FGFR1c placed on the site
  • hFGF21 in Not Cleaved in FAP KO Mice
  • Fc-hFGF21 is more stable in FAP KO mice
  • FAR cleaves Endogenously Produced FGF21 In Vivo in monkeys and in dogs
  • The FAP Cleavage Consensus GLY-Pro is COnserved in most mammalian FGF21
  • FAP Does not Cleave the C-Terminal Residues of Mouse FGF21
  • Human: FAP, DPPIV
  • Mouse: FAP, DPP4
  • FAP INhibition
  • FAP is Overexpressed in Liver with Steatohepatitis: Early NASH vs Late NASH
  • Proposal: FAP Inhibition for FGF21 Stabilization in NASH
  1. Fatty hepatocytes – e.g. NASH
  2. Activated stellate cells, e.g. NASH

 

10:55 Thyroid Hormone Receptor Beta (THR-ß) Agonist for NASH: Correcting a Primary Deficiency in NASH Livers

Rebecca Taub, M.D., Ph.D., CEO, Madrigal Pharmaceuticals

NASH patients typically have metabolic syndrome including diabetes, dyslipidemia, obesity, and primarily die of cardiovascular disease. Hypothyroidism at the level of the thyroid gland and liver-specific hypothyroidism are common in NASH. Based on clinical and preclinical data, Thyroid receptor beta agonists decrease insulin resistance, reduce LDL-C, triglycerides fatty liver, inflammation and fibrosis in NASH. The target will also provide CV benefit to patients with NASH. MGL-3196 is a highly THR-ß selective liver-directed once daily oral medication that has shown excellent safety and lipid-lowering efficacy in humans; unlike prior thyroid receptor agonist(s), no cartilage findings in chronic toxicology or ALT increases in human studies. MGL-3196 is being advanced in Phase II studies in patients with genetic dyslipidemia or NASH.

Madrigal Portfolio of drugs:

  • MGL-3196: First-in-Class THR-Beta Agonist – discovered first at ROCHE – THR-beta selective targeted to the Liver – regulated by THR-Alpha  – in Phase II – no side effects on bone
  • Large & underserved Markets in NASH
  • Phase 2 HeFH Patients
  1. Hypothyroidism common in NASH patients
  2. Liver-specific Hypothyroidism present in human NASH degradation of thyroid hormone increases deiodised 9DIO) 3 produced by Stelllate cells in NASH liver
  3. Treating NASHrather than fibrosis is key in addressing the disease – approvable endpoint
  4. THR – Thyroid hormone reduces Cholesterol
  5. Thyroid hormone T3 thyroxine – treatment amy cause osteoporosis
  6. MGL 0 3196: Liver size, Live Triglycerides, Improve Insulin tolerance, decrease ALT
  7. Reduction of key NASH, Fibrosis Pathway Genes at Human Comparable Drug levels
  8. THR-beta: Decreased Liver Fibrosis, Apoptosis in mice:

HUMAN DATA

  • Single ascending dose study
  • Multiple – ascending studies: LDL and TG decrease
  • decrease Non-HDL CHolesterol
  • Decrease Apolipoprotein B
  • Pleiotropic Pioglitazone Effect in NASH at 6 month treatment and biopsy of liver – dramatic effect in NASH – ten years ago study
  • PPAR gamma agonist – NEGATIVE SIDE EFFECTS: weight gain, CHF, Bone osteoporosis
  • Anti-inflammatory: well tolerated

No Single NASH Therapeutics – Conbination agents

MGL – 3196 Phase 2 – Study: Proposed Phase 2 Proof of COncepts NASH Protocol

  • Unmet needs in FH, a severeGenetic Dyslipedemia
  • Weight loss in 6 weeksreduction in cholesterol and TG
  • Likelihood of Success
  • second study after 9 months
  • is different on NASH Patients in 12 weeks using MRI on Liver
  • prevalence
  • HeFH, PCSK9 inhibitors plus standard care
  • Unique and Complementary Lipid Lowering Profile
  1. Lowers Lp(a) and severely atherogenic practice
  2. Proposed Phase 2 HeFH Patients

 

11:25 Enjoy Lunch on Your Own

 

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Hybrid lipid bioelectronic membranes

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Hybrid solid-state chips and biological cells integrated at molecular level

Biological ion channels combine with solid-state transistors to create a new kind of hybrid bioelectronics. Imagine chips with dog-like capability to taste and smell, or even recognize specific molecules.
http://www.kurzweilai.net/hybrid-solid-state-chips-and-biological-cells-integrated-at-molecular-level
Illustration depicting a biocell attached to a CMOS integrated circuit with a membrane containing sodium-potassium pumps in pores. Energy is stored chemically in ATP molecules. When the energy is released as charged ions (which are then converted to electrons to power the chip at the bottom of the experimental device), the ATP is converted to ADP + inorganic phosphate. (credit: Trevor Finney and Jared Roseman/Columbia Engineering)

Columbia Engineering researchers have combined biological and solid-state components for the first time, opening the door to creating entirely new artificial biosystems.

In this experiment, they used a biological cell to power a conventional solid-state complementary metal-oxide-semiconductor (CMOS) integrated circuit. An artificial lipid bilayer membrane containing adenosine triphosphate (ATP)-powered ion pumps (which provide energy for cells) was used as a source of ions (which were converted to electrons to power the chip).

The study, led by Ken Shepard, Lau Family Professor of Electrical Engineering and professor of biomedical engineering at Columbia Engineering, was published online today (Dec. 7, 2015) in an open-access paper in Nature Communications.

How to build a hybrid biochip

Living systems achieve this functionality with their own version of electronics based on lipid membranes and ion channels and pumps, which act as a kind of “biological transistor.” Charge in the form of ions carry energy and information, and ion channels control the flow of ions across cell membranes.

Solid-state systems, such as those in computers and communication devices, use electrons; their electronic signaling and power are controlled by field-effect transistors.

To build a prototype of their hybrid system, Shepard’s team packaged a CMOS integrated circuit (IC) with an ATP-harvesting “biocell.” In the presence of ATP, the system pumped ions across the membrane, producing an electrical potential (voltage)* that was harvested by the integrated circuit.

“We made a macroscale version of this system, at the scale of several millimeters, to see if it worked,” Shepard notes. “Our results provide new insight into a generalized circuit model, enabling us to determine the conditions to maximize the efficiency of harnessing chemical energy through the action of these ion pumps. We will now be looking at how to scale the system down.”

While other groups have harvested energy from living systems, Shepard and his team are exploring how to do this at the molecular level, isolating just the desired function and interfacing this with electronics. “We don’t need the whole cell,” he explains. “We just grab the component of the cell that’s doing what we want. For this project, we isolated the ATPases because they were the proteins that allowed us to extract energy from ATP.”

The capability of a bomb-sniffing dog, no Alpo required

Next, the researchers plan to go much further, such as recognizing specific molecules and giving chips the potential to taste and smell.

The ability to build a system that combines the power of solid-state electronics with the capabilities of biological components has great promise, they believe. “You need a bomb-sniffing dog now, but if you can take just the part of the dog that is useful — the molecules that are doing the sensing — we wouldn’t need the whole animal,” says Shepard.

The technology could also provide a power source for implanted electronic devices in ATP-rich environments such as inside living cells, the researchers suggest.

*  “In general, integrated circuits, even when operated at the point of minimum energy in subthreshold, consume on the order of 10−2 W mm−2 (or assuming a typical silicon chip thickness of 250 μm, 4 × 10−2 W mm−3). Typical cells, in contrast, consume on the order of 4 × 10−6 W mm−3. In the experiment, a typical active power dissipation for the IC circuit was 92.3 nW, and the active average harvesting power was 71.4 fW for the biocell (the discrepancy is managed through duty-cycled operation of the IC).” — Jared M. Roseman et al./Nature Communications

 

Hybrid integrated biological–solid-state system powered with adenosine triphosphate

Jared M. RosemanJianxun LinSiddharth RamakrishnanJacob K. Rosenstein & Kenneth L. Shepard
Nature Communications 7 Dec 2015; 6(10070)
     http://dx.doi.org:/10.1038/ncomms10070

There is enormous potential in combining the capabilities of the biological and the solid state to create hybrid engineered systems. While there have been recent efforts to harness power from naturally occurring potentials in living systems in plants and animals to power complementary metal-oxide-semiconductor integrated circuits, here we report the first successful effort to isolate the energetics of an electrogenic ion pump in an engineered in vitro environment to power such an artificial system. An integrated circuit is powered by adenosine triphosphate through the action of Na+/K+ adenosine triphosphatases in an integrated in vitro lipid bilayer membrane. The ion pumps (active in the membrane at numbers exceeding 2 × 106mm−2) are able to sustain a short-circuit current of 32.6pAmm−2 and an open-circuit voltage of 78mV, providing for a maximum power transfer of 1.27pWmm−2 from a single bilayer. Two series-stacked bilayers provide a voltage sufficient to operate an integrated circuit with a conversion efficiency of chemical to electrical energy of 14.9%.

 

Figure 1: Fully hybrid biological–solid-state system.

 

 

Fully hybrid biological-solid-state system.

http://www.nature.com/ncomms/2015/151207/ncomms10070/images/ncomms10070-f1.jpg

(a) Illustration depicting biocell attached to CMOS integrated circuit. (b) Illustration of membrane in pore containing sodium–potassium pumps. (c) Circuit model of equivalent stacked membranes, =2.1pA, =98.6G, =575G and =75pF, Ag/AgCl electrode equivalent resistance RWE+RCE<20k, energy-harvesting capacitor CSTOR=100nF combined with switch as an impedance transformation network (only one switch necessary due to small duty cycle), and CMOS IC voltage doubler and resistor representing digital switching load. RL represents the four independent ring oscillator loads. (d) Equivalent circuit detail of stacked biocell. (e) Switched-capacitor voltage doubler circuit schematic.

 

The energetics of living systems are based on electrochemical membrane potentials that are present in cell plasma membranes, the inner membrane of mitochondria, or the thylakoid membrane of chloroplasts1. In the latter two cases, the specific membrane potential is known as the proton-motive force and is used by proton adenosine triphosphate (ATP) synthases to produce ATP. In the former case, Na+/K+-ATPases hydrolyse ATP to maintain the resting potential in most cells.

While there have been recent efforts to harness power from some naturally occurring potentials in living systems that are the result of ion pump action both in plants2 and animals3, 4 to power complementary metal-oxide semiconductor (CMOS) integrated circuits (ICs), this work is the first successful effort to isolate the energetics of an electrogenic ion pump in an engineered in vitroenvironment to power such an artificial system. Prior efforts to harness power from in vitromembrane systems incorporating ion-pumping ATPases5, 6, 7, 8, 9 and light-activated bacteriorhodopsin9, 10, 11 have been limited by difficulty in incorporating these proteins in sufficient quantity to attain measurable current and in achieving sufficiently large membrane resistances to harness these currents. Both problems are solved in this effort to power an IC from ATP in an in vitro environment. The resulting measurements provide new insight into a generalized circuit model, which allows us to determine the conditions to maximize the efficiency of harnessing chemical energy through the action of electrogenic ion pumps.

 

ATP-powered IC

Figure 1a shows the complete hybrid integrated system, consisting of a CMOS IC packaged with an ATP-harvesting ‘biocell’. The biocell consists of two series-stacked ATPase bearing suspended lipid bilayers with a fluid chamber directly on top of the IC. Series stacking of two membranes is necessary to provide the required start-up voltage for IC and eliminates the need for an external energy source, which is typically required to start circuits from low-voltage supplies2, 3. As shown inFig. 1c, a matching network in the form of a switched capacitor allows the load resistance of the IC to be matched to that presented by the biocell. In principle, the switch S can be implicit. The biocell charges CSTOR until the self start-up voltage, Vstart, is reached. The chip then operates until the biocell voltage drops below the minimum supply voltage for operation, Vmin. Active current draw from the IC stops at this point, allowing the charge to build up again on CSTOR. In our case, however, the IC leakage current exceeds 13.5nA at Vstart, more than can be provided by the biocell. As a result, an explicit transistor switch and comparator (outside of the IC) are used for this function in the experimental results presented here, which are not powered by the biocell and not included in energy efficiency calculations (see Supplementary Discussion for additional details). The energy from the biocell is used to operate a voltage converter (voltage doubler) and some simple inverter-based ring oscillators in the IC, which receive power from no other sources.

Figure 1: Fully hybrid biological–solid-state system.

http://www.nature.com/ncomms/2015/151207/ncomms10070/images/ncomms10070-f1.jpg

 

……..   Prior to the addition of ATP, the membrane produces no electrical power and has an Rm of 280G. A 1.7-pA short-circuit (SC) current (Fig. 2b) through the membrane is observed upon the addition of ATP (final concentration 3mM) to the cis chamber where functional, properly oriented enzymes generate a net electrogenic pump current. To perform these measurements, currents through each membrane of the biocell are measured using a voltage-clamp amplifier (inset of Fig. 2b) with a gain of 500G with special efforts taken to compensate amplifier leakage currents. Each ATPase transports three Na+ ions from the cis chamber to the trans chamber and two K+ ions from thetrans chamber to the cis chamber (a net charge movement of one cation) for every molecule of ATP hydrolysed. At a rate of 100 hydrolysis events per second under zero electrical (SC) bias13, this results in an electrogenic current of ~16aA. The observed SC current corresponds to about 105 active ATPases in the membrane or a concentration of about 2 × 106mm−2, about 5% of the density of channels occurring naturally in mammalian nerve fibres14. It is expected that half of the channels inserted are inactive because they are oriented incorrectly.

Figure 2: Single-cell biocell characterization.

http://www.nature.com/ncomms/2015/151207/ncomms10070/images_article/ncomms10070-f2.jpg

(a)…Pre-ATP data linear fit (black line) slope yield Rm=280G. Post ATP data fit to a Boltzmann curve, slope=0.02V (blue line). Post-ATP linear fit (red line) yields Ip=−1.8pA and Rp=61.6G, which corresponds to a per-ATP source resistance of 6.16 × 1015. The current due to membrane leakage through R_{m} is subtracted in the post-ATP curve…. (b)…

 

Current–voltage characteristics of the ATPases

Figure 2a shows the complete measured current–voltage (IV) characteristic of a single ATPase-bearing membrane in the presence of ATP. The current due to membrane leakage through Rm is subtracted in the post-ATP curve. The IV characteristic fits a Boltzmann sigmoid curve, consistent with sodium–potassium pump currents measured on membrane patches at similar buffer conditions13, 15, 16. This nonlinear behaviour reflects the fact that the full ATPase transport cycle (three Na+ ions from cis to trans and two K+ ions from trans to cis) time increases (the turn-over rate, kATP, decreases) as the membrane potential increases16. No effect on pump current is expected from any ion concentration gradients produced by the action of the ATPases (seeSupplementary Discussion). Using this Boltzmann fit, we can model the biocell as a nonlinear voltage-controlled current source IATPase (inset Fig. 2a), in which the current produced by this source varies as a function of Vm. In the fourth quadrant, where the cell is producing electrical power, this model can be linearized as a Norton equivalent circuit, consisting of a DC current source (Ip) in parallel with a current-limiting resistor (Rp), which acts to limit the current delivered to the load at increasing bias (IATPase~IpVm/Rp). Figure 2c shows the measured and simulated charging of Cm for a single membrane (open-circuited voltage). A custom amplifier with input resistance Rin>10T was required for this measurement (see Electrical Measurement Methods).

 

Reconciling operating voltage differences

The electrical characteristics of biological systems and solid-state systems are mismatched in their operating voltages. The minimum operating voltage of solid-state systems is determined by the need for transistors to modulate a Maxwell–Boltzmann (MB) distribution of carriers by several orders of magnitude through the application of a potential that is several multiples of kT/q (where kis Boltzmann’s constant, T is the temperature in degrees Kelvin and q is the elementary charge). Biological systems, while operating under the same MB statistics, have no such constraints for operating ion channels since they are controlled by mechanical (or other conformational) processes rather than through modulation of a potential barrier. To bridge this operating voltage mismatch, the circuit includes a switched-capacitor voltage doubler (Fig. 1d) that is capable of self-startup from voltages as low Vstart=145mV (~5.5kT/q) and can be operated continuously from input voltages from as low as Vmin=110mV (see Supplementary Discussion)…..

 

Maximizing the efficiency of harvesting energy from ATP

Solid-state systems and biological systems are also mismatched in their operating impedances. In our case, the biocell presents a source impedance, =84.2G, while the load impedance presented by the complete integrated circuit (including both the voltage converter and ring oscillator loads) is approximately RIC=200k. (The load impedance, RL, of the ring oscillators alone is 305k.) This mismatch in source and load impedance is manifest in large differences in power densities. In general, integrated circuits, even when operated at the point of minimum energy in subthreshold, consume on the order of 10−2Wmm−2 (or assuming a typical silicon chip thickness of 250μm, 4 × 10−2Wmm−3) (ref. 17). Typical cells, in contrast, consume on the order of 4 × 10−6Wmm−3 (ref. 18). In our case, a typical active power dissipation for our circuit is 92.3nW, and the active average harvesting power is 71.4fW for the biocell. This discrepancy is managed through duty-cycled operation of the IC in which the circuit is largely disabled for long periods of time (Tcharge), integrating up the power onto a storage capacitor (CSTOR), which is then expended in a very brief period of activity (Trun), as shown in Fig. 3a.

The overall efficiency of the system in converting chemical energy to the energy consumed in the load ring oscillator (η) is given by the product of the conversion efficiency of the voltage doubler (ηconverter) and the conversion efficiency of chemical energy to electrical energy in the biocell (ηbiocell), η=ηconverter × ηbiocell. ηconverter is relatively constant over the range of input voltages at ~59%, as determined by various loading test circuits included in the chip design (Supplementary Figs 1–6). ηbiocell, however, varies with transmembrane potential Vm. η is the efficiency in transferring power to the power ring oscillator loads from the ATP harvested by biocell.

…….

To first order, the energy made available to the Na+/K+-ATPase by the hydrolysis of ATP is independent of the chemical or electric potential of the membrane and is given by |ΔGATP|/(qNA), where ΔGATP is the Gibbs free energy change due to the ATP hydrolysis reaction per mole of ATP at given buffer conditions and NA is Avogadro’s number. Since every charge that passes through IATPase corresponds to a single hydrolysis event, we can use two voltage sources in series with IATPase to independently account for the energy expended by the pumps both in moving charge across the electric potential difference and in moving ions across the chemical potential difference. The dependent voltage source Vloss in this branch fixes the voltage across IATPase, and the total power produced by the pump current source is (|ΔGATP|/NA)(NkATP), which is the product of the energy released per molecule of ATP, the number of active ATPases and the ATP turnover rate. The power dissipated in voltage source Vchem models the work performed by the ATPases in transporting ions against a concentration gradient. In the case of the Na+/K+ ATPase,Vchem is given by . The power dissipated in this source is introduced back into the circuit in the power generated by the Nernst independent voltage sources, and . The power dissipated in the dependent voltage source Vloss models any additional power not used to perform chemical or electrical work. ……

 

Integration of ATP-harvesting ion pumps could provide a means to power future CMOS microsystems scaled to the level of individual cells22. In molecular diagnostics, the integration of pore-forming proteins such as alpha haemolysin23 or MspA porin24 with CMOS electronics is already finding application in DNA sequencing25. Exploiting the large diversity of function available in transmembrane proteins in these hybrid systems could, for example, lead to highly specific sensing platforms for airborne odorants or soluble molecular entities26, 27. Heavily multiplexed platforms could become high-throughput in vitro drug-screening platforms against this diversity of function. In addition, integration of transmembrane proteins with CMOS may become a convenient alternative to fluorescence for coupling to synthetic biological systems28.

 

Roseman, J. M. et al. Hybrid integrated biological–solid-state system powered with adenosine triphosphate. Nat. Commun. 6:10070      http://dx.doi.org:/10.1038/ncomms10070 (2015).

 

 

  • Rottenberg, H. The measurement of membrane potential and deltapH in cells, organelles, and vesicles. Methods Enzymol. 55, 547569 (1979).
  • Himes, C., Carlson, E., Ricchiuti, R. J., Otis, B. P. & Parviz, B. A. Ultralow voltage nanoelectronics powered directly, and solely, from a tree. IEEE Trans. Nanotechnol. 9, 25(2010).
  • Mercier, P. P., Lysaght, A. C., Bandyopadhyay, S., Chandrakasan, A. P. & Stankovic, K. M.Energy extraction from the biologic battery in the inner ear. Nat. Biotechnol. 30, 12401243(2012).
  • Halámková, L. et al. Implanted Biofuel Cell Operating in a Living Snail. J. Am. Chem. Soc.134, 50405043 (2012).

 

 

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brown adipocyte protein CIDEA promotes lipid droplet fusion

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

 

The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding

Parker, Nicholas T Ktistakis, Ann M Dixon, Judith Klein-Seetharaman, Susan Henry, Mark Christian Dirk Dormann, Gil-Soo Han, Stephen A Jesch, George M Carman, Valerian Kagan, et al.

eLife 2015;10.7554/eLife.07485     http://dx.doi.org/10.7554/eLife.07485

 

Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD-LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat.

 

Evolutionary pressures for survival in fluctuating environments that expose organisms to times of both feast and famine have selected for the ability to efficiently store and release energy in the form of triacyclglycerol (TAG). However, excessive or defective lipid storage is a key feature of common diseases such as diabetes, atherosclerosis and the metabolic syndrome (1). The organelles that are essential for storing and mobilizing intracellular fat are lipid droplets (LDs) (2). They constitute a unique cellular structure where a core of neutral lipids is stabilized in the hydrophilic cytosol by a phospholipid monolayer embedding LD-proteins. While most mammalian 46 cells present small LDs (<1 Pm) (3), white (unilocular) adipocytes contain a single giant LD occupying most of their cell volume. In contrast, brown (multilocular) adipocytes hold multiple LDs of lesser size, increasing the LD surface/volume ratio which facilitates the rapid consumption of lipids for adaptive thermogenesis (4).

The exploration of new approaches for the treatment of metabolic disorders has been stimulated by the rediscovery of active brown adipose tissue (BAT) in adult humans (5, 6) and by the induction of multilocular brown-like cells in white adipose tissue (WAT) (7). The multilocular morphology of brown adipocytes is a defining characteristic of these cells along with expression of genes such as Ucp1. The acquisition of a unilocular or multilocular phenotype is likely to be controlled by the regulation of LD growth. Two related proteins, CIDEA and CIDEC promote LD enlargement in adipocytes (8-10), with CIDEA being specifically found in BAT. Together with CIDEB, they form the CIDE (cell death-inducing DFF45-like effector) family of LD-proteins, which have emerged as important metabolic regulators (11).

Different mechanisms have been proposed for LD enlargement, including in situ neutral lipid synthesis, lipid uptake and LD-LD coalescence (12-14). The study of CIDE 62 proteins has revealed a critical role in the LD fusion process in which a donor LD progressively transfers its content to an acceptor LD until it is completely absorbed (15). However, the underlying mechanism by which CIDEC and CIDEA facilitate the interchange of triacylglycerol (TAG) molecules between LDs is not understood. In the present study, we have obtained a detailed picture of the different steps driving this LD enlargement process, which involves the stabilization of LD pairs, phospholipid binding, and the permeabilization of the LD monolayer to allow the transference of lipids.

 

CIDEA expression mimics the LD dynamics observed during the differentiation of brown adipocytes

Phases of CIDEA activity: LD targeting, LD-LD docking and LD growth

A cationic amphipathic helix in C-term drives LD targeting

The amphipathic helix is essential for LD enlargement

LD-LD docking is induced by the formation of CIDEA complexes

CIDEC differs from CIDEA in its dependence on the N-term domain

CIDEA interacts with Phosphatidic Acid

PA is required for LD enlargement

 

The Cidea gene is highly expressed in BAT, induced in WAT following cold exposure (46), and is widely used by researchers as a defining marker to discriminate brown or brite adipocytes from white adipocytes (7, 28). As evidence indicated a key role in the LD biology (47) we have characterized the mechanism by which CIDEA promotes LD enlargement, which involves the targeting of LDs, the docking of LD pairs and the transference of lipids between them. The lipid transfer step requires the interaction of CIDEA and PA through a cationic amphipathic helix. Independently of PA-binding, this helix is also responsible for anchoring CIDEA in the LD membrane. Finally, we demonstrate that the docking of LD pairs is driven by the formation of CIDEA complexes involving the N-term domain and a C-term interaction site.

CIDE proteins appeared during vertebrate evolution by the combination of an ancestor N-term domain and a LD-binding C-term domain (35). In spite of this, the full process of LD enlargement can be induced in yeast by the sole exogenous expression of 395 CIDEA, indicating that in contrast to SNARE-triggered vesicle fusion, LD fusion by lipid transference does not require the coordination of multiple specific proteins (48). Whereas vesicle fusion implicates an intricate restructuring of the phospholipid bilayers, LD fusion is a spontaneous process that the cell has to prevent by tightly controlling their phospholipid composition (23). However, although phospholipid-modifying enzymes have been linked with the biogenesis of LDs (49, 50), the implication of phospholipids in physiologic LD fusion processes has not been previously described.

Complete LD fusion by lipid transfer can last several hours, during which the participating LDs remain in contact. Our results indicate that both the N-term domain and a C-term dimerization site (aa 126-155) independently participate in the docking of LD pairs by forming trans interactions (Fig. 7). Certain mutations in the dimerization sites that do not eliminate the interaction result in a decrease on the TAG transference efficiency, reflected on the presence of small LDs docked to enlarged LDs. This suggests that in addition to stabilizing the LD-LD interaction, the correct conformation of the 409 CIDEA complexes is necessary for optimal TAG transfer. Furthermore, the formation of stable LD pairs is not sufficient to trigger LD fusion by lipid transfer. In fact, although LDs can be tightly packed in cultured adipocytes, no TAG transference across neighbour LDs is observed in the absence of CIDE proteins (15), showing that the phospholipid monolayer acts as a barrier impermeable to TAG. Our CG-MD simulations indicate that certain TAG molecules can escape the neutral lipid core of the LD and be integrated within the aliphatic chains of the phospholipid monolayer. This could be a transition state 416 prior to the TAG transference and our data indicates that the docking of the amphipathic helix in the LD membrane could facilitate this process. However, the infiltrated TAGs in LD membranes in the presence of mutant helices, or even in the absence of docking, suggests that this is not enough to complete the TAG transference.

To be transferred to the adjacent LD, the TAGs integrated in the hydrophobic region of the LD membrane should cross the energy barrier defined by the phospholipid polar heads, and the interaction of CIDEA with PA could play a role in this process, as suggested by the disruption of LD enlargement by the mutations preventing PA-binding (K167E/R171E/R175E) and the inhibition of CIDEA after PA depletion. The minor effects observed with more conservative substitutions in the helix, suggests that the presence of positive charges is sufficient to induce TAG transference by attracting anionic phospholipids present in the LD membrane. PA, which requirement is indicated by our PA-depletion experiments, is a cone-shaped anionic phospholipid which could locally destabilize the LD monolayer by favoring a negative membrane curvature incompatible with the spherical LD morphology (51). Interestingly, while the zwitterion PC, the main component of the monolayer, stabilizes the LD structure (23), the negatively charged PA promote their coalescence (29). This is supported by our CD-MD results which resulted in a deformation of the LD shape by the addition of PA. We propose a model in which the C-term amphipathic helix positions itself in the LD monolayer and interacts with PA molecules in its vicinity, which might include trans interactions with PA in the adjacent LD. The interaction with PA disturbs the integrity of the phospholipid barrier at the LD-LD interface, allowing the LD to LD transference of TAG molecules integrated in the LD membrane (Fig. 7). Additional alterations in the LD composition could be facilitating TAG transference, as differentiating adipocytes experience a reduction in saturated fatty acids in the LD phospholipids (52), and in their PC/PE ratio (53) which could increase the permeability of the LD membranes, and we previously observed that a change in the molecular structures of TAG results in an altered migration pattern to the LD surface (32).

During LD fusion by lipid transfer, the pressure gradient experienced by LDs favors TAG flux from small to large LDs (15). However, the implication of PA, a minor component of the LD membrane, could represent a control mechanism, as it is plausible that the cell could actively influence the TAG flux direction by differently regulating the levels of PA in large and small LDs, which could be controlled by the activity of enzymes such as AGPAT3 and LIPIN-1J (13, 30). This is a remarkable possibility, as a switch in the favored TAG flux direction could promote the acquisition of a multilocular phenotype and facilitate the browning of WAT (24). Interestingly, Cidea mRNA is the LD protein- encoding transcript that experiences the greatest increase during the cold-induced process by which multilocular BAT-like cells appear in WAT (24). Furthermore, in BAT, cold exposure instigates a profound increase in CIDEA protein levels that is independent of transcriptional regulation (54). The profound increase in CIDEA is coincident with elevated lipolysis and de novo lipogenesis that occurs in both brown and white adipose tissues after E-adrenergic receptor activation (55). It is likely that CIDEA has a central role in coupling these processes to package newly synthesized TAG in LDs for subsequent lipolysis and fatty acid oxidation. Importantly, BAT displays high levels of glycerol kinase activity (56, 57) that facilitates glycerol recycling rather than release into the blood stream, following induction of lipolysis (58), which occurs in WAT. Hence, the reported elevated glycerol released from cells depleted of CIDEA (28) is likely to be a result of decoupling lipolysis from the ability to efficiently store the products of lipogenesis in LDs and therefore producing a net increase in detected extracellular glycerol. This important role of CIDEA is supported by the marked depletion of TAG in the BAT of Cidea null mice following overnight exposure to 4 °C (28) and our findings that CIDEA-dependent LD enlargement is maintained in a lipase negative yeast strain.

Cidea and the genes that are required to facilitate high rates of lipolysis and lipogenesis are associated with the “browning” of white fat either following cold exposure (46) or in genetic models such as RIP140 knockout WAT (59). The induction of a brown- like phenotype in WAT has potential benefits in the treatment and prevention of metabolic disorders (60). Differences in the activity and regulation of CIDEC and CIDEA could also be responsible for the adoption of unilocular or multilocular phenotypes. In addition to their differential interaction with PLIN1 and 5, we have observed that CIDEC is more resilient to the deletion of the N-term than CIDEA, indicating that it may be less sensitive to regulatory posttranslational modifications of this domain. This robustness of CIDEC activity together with its potentiation by PLIN1, could facilitate the continuity of the LD enlargement in white adipocytes until the unilocular phenotype is achieved. In contrast, in brown adipocytes expressing CIDEA the process would be stopped at the multilocular stage for example due to post-translational modifications that modulate the function or stability of the protein or alteration of the PA levels in LDs.

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reducing obesity-related inflammation

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

NIH researchers find potential target for reducing obesity-related inflammation

Study sheds light on preventing or reversing certain obesity-associated diseases.

http://www.nih.gov/news-events/news-releases/nih-researchers-find-potential-target-reducing-obesity-related-inflammation

Scientists at the National Institutes of Health have identified a potential molecular target for reducing obesity-related inflammation. Researchers have known that overeating (that is, excess calorie consumption) by individuals with obesity often triggers inflammation, which has been linked to such diseases as asthma and Type 2 diabetes. In their study, published recently in The Journal of Clinical Investigation (Nov. 3, 2015, online version(link is external)), the investigators found that a protein called SIRT3 provides resistance to this inflammatory response and could potentially prevent or reverse obesity-associated diseases of inflammation.

Lead researcher Michael N. Sack, M.D., Ph.D., a senior investigator at NIH’s National Heart, Lung, and Blood Institute, explained that he and his team identified the role of SIRT3 through an investigation involving 19 healthy volunteers who fasted for a 24-hour period.

“Previous research has shown that intermittent fasting or intermittent calorie restriction — by way of eating fewer calories for a few days a month — reduces inflammation,” said Dr. Sack. “We found through our study that this effect is mediated, in part, on a molecular level when SIRT3 blocks the activity of another molecule known as the NLRP3 inflammasome.” He explained that NLRP3 inflammasomes are components of an intracelluar immune response triggered when mitochondria undergo stress, such as from excess calorie intake.

By using cultured cells from a group of eight volunteers who did not fast, Dr. Sack and his team found evidence suggesting that SIRT3 can be activated not only through fasting, but also through the use of nicotinamide riboside, a vitamin B derivative. “Taken together, these early results point to a potential mechanism for addressing obesity-related inflammation, and thus diseases linked to this type of inflammation, such as asthma, Type 2 diabetes, rheumatoid arthritis, and atherosclerosis — conditions associated with a reduced quality of life and/or premature death,” Dr. Sack said.

Obesity remains a substantial health problem for the nation, affecting more than a third of adults and 17 percent of children, according to the Centers for Disease Control and Prevention. Efforts to manage weight, however, can be hindered by the effects of obesity-related diseases. “It is a vicious cycle,” said Dr. Sack. “Take asthma for example. An increase in obesity incidence has been associated with an increase in asthma incidence, but asthma makes it difficult for some to be physically active enough to lose weight.”

Dr. Sack and colleagues — who include researchers from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and Weill Cornell Medical College — are conducting a follow-up study at the NIH Clinical Center to determine whether the vitamin B derivative nicotinamide riboside can specifically reduce bronchial inflammation in individuals with asthma. If the results of the study are promising, Dr. Sack and colleagues will aim to conduct larger clinical trials to validate the findings and potentially inform treatment of obesity-related inflammation in asthma.

The National Heart, Lung, and Blood Institute (NHLBI) plans, conducts, and supports research related to the causes, prevention, diagnosis, and treatment of heart, blood vessel, lung, and blood diseases; and sleep disorders. The Institute also administers national health education campaigns on women and heart disease, healthy weight for children, and other topics. NHLBI press releases and other materials are available online at www.nhlbi.nih.gov.

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