Growth Differentiation Factor 11 Levels Research Articles

Is Growth Differentiation Factor 11 a Realistic Therapeutic for Aging-Dependent Muscle Defects?

This "Controversies in Cardiovascular Research" article evaluates the evidence for and against the hypothesis that the circulating blood level of growth differentiation factor 11 (GDF11) decreases in old age and that restoring normal GDF11 levels in old animals rejuvenates their skeletal muscle and reverses pathological cardiac hypertrophy and cardiac dysfunction. Studies supporting the original GDF11 hypothesis in skeletal and cardiac muscle have not been validated by several independent groups. These new studies have either found no effects of restoring normal GDF11 levels on cardiac structure and function or have shown that increasing GDF11 or its closely related family member growth differentiation factor 8 actually impairs skeletal muscle repair in old animals. One possible explanation for what seems to be mutually exclusive findings is that the original reagent used to measure GDF11 levels also detected many other molecules so that age-dependent changes in GDF11 are still not well known. The more important issue is whether increasing blood [GDF11] repairs old skeletal muscle and reverses age-related cardiac pathologies. There are substantial new and existing data showing that GDF8/11 can exacerbate rather than rejuvenate skeletal muscle injury in old animals. There is also new evidence disputing the idea that there is pathological hypertrophy in old C57bl6 mice and that GDF11 therapy can reverse cardiac pathologies. Finally, high [GDF11] causes reductions in body and heart weight in both young and old animals, suggestive of a cachexia effect. Our conclusion is that elevating blood levels of GDF11 in the aged might cause more harm than good.

Circulating Concentrations of Growth Differentiation Factor 11 Are Heritable and Correlate With Life Span.

Growth differentiation factor 11 (GDF11) is member of the transforming growth factor β (TGF-β) superfamily of proteins. Circulating GDF11 concentrations appear to decline with age, and its depletion is associated with cardiac hypertrophy and other morbidities. Knowledge of GDF11 regulation is limited, and the effects of natural genetic variation on GDF11 levels are currently undefined. We tested whether genetic background determines serum GDF11 concentrations using two classical inbred mouse strains: C57BL/6J (B6) and BALB/cByJ (BALB). B6 mice exhibited significantly higher GDF11 levels than BALB mice, and these strain differences were consistent throughout the life span. Overall, interactions between age and genetic background determined GDF11 concentrations, which were unaffected by sex. We then surveyed a panel of 22 genetically diverse inbred mouse strains and discovered a sixfold range in GDF11 levels at middle age. We estimated that 74.52% of phenotypic variation in GDF11 levels was attributable to genetic background. We used the Mouse Phenome Database to screen for phenotypes that correlate with GDF11. Interestingly, GDF11 levels predicted median strain life spans. This study revealed high heritability of GDF11 levels. Furthermore, our correlative data suggest that GDF11 may serve as a novel predictor of mammalian life span.

Circulating Growth Differentiation Factor 11/8 Levels Decline With Age

Growth differentiation factor 11 (GDF11) and GDF8 are members of the transforming growth factor-β superfamily sharing 89% protein sequence homology. We have previously shown that circulating GDF11 levels decrease with age in mice. However, a recent study by Egerman et al reported that GDF11/8 levels increase with age in mouse serum. Here, we clarify the direction of change of circulating GDF11/8 levels with age and investigate the effects of GDF11 administration on the murine heart. We validated our previous finding that circulating levels of GDF11/8 decline with age in mice, rats, horses, and sheep. Furthermore, we showed by Western analysis that the apparent age-dependent increase in GDF11 levels, as reported by Egerman et al, is attributable to cross-reactivity of the anti-GDF11 antibody with immunoglobulin, which is known to increase with age. GDF11 administration in mice rapidly activated SMAD2 and SMAD3 signaling in myocardium in vivo and decreased cardiac mass in both young (2-month-old) and old (22-month-old) mice in a dose-dependent manner after only 9 days. Our study confirms an age-dependent decline in serum GDF11/8 levels in multiple mammalian species and that exogenous GDF11 rapidly activates SMAD signaling and reduces cardiomyocyte size. Unraveling the molecular basis for the age-dependent decline in GDF11/8 could yield insight into age-dependent cardiac pathologies.

Reduced Circulating GDF11 Is Unlikely Responsible for Age-Dependent Changes in Mouse Heart, Muscle, and Brain.

Recent high-profile studies report conflicting data on the age-related change in circulating growth/differentiation factor 11 (GDF11) and myostatin as well as the former's influence on muscle regeneration. Both ligands bind and activate ActRIIB receptors with similar affinities and should therefore have similar actions, yet these studies suggest that GDF11 activates muscle regeneration whereas myostatin is well known to inhibit it. They also suggest that circulating GDF11 levels, but not those of myostatin, decline with age. We performed a careful assessment of the ELISA used to quantify circulating myostatin in these studies and determined that assay reagents significantly cross react with each protein, each of which is highly homologous. Circulating myostatin levels decreased with age and estimates of GDF11 levels using myostatin null mice indicate that they were almost 500 times lower than those for myostatin. This suggests that circulating GDF11 has little physiological relevance as it could not outcompete myostatin for ActRIIB binding sites. Together, these results further suggest that the previously reported aging muscle, heart, and brain phenotypes attributed to reduced circulating GDF11 should be reconsidered.

Abstract 253: Restoring GDF11 to Normal Levels in Old Mice Has no Effect on Cardiac Structure and Function

Rationale: GDF11 (Growth Differentiation Factor 11) is a member of the TGFβ super family of secreted factors, which play an important role in the regulation of cell processes including proliferation, differentiation, death, adhesion, and migration. Recently it was shown that circulating GDF11 levels fall with aging and this change is associated with pathological cardiac hypertrophy (PCH). Restoring GDF11 to normal levels was shown to rescue PCH. Objective: To determine if we can confirm the hypothesis that correcting the levels of a single factor, GDF11, determines aging related PCH. Methods and Results: We used the study design described by Loffredo et al, 2013. Investigators were blinded to treatment group. 24 month old C57BL/6 male mice were given a daily injection of recombinant GDF11 at 0 .1mg/kg or vehicle for 28 days. GDF11 bioactivity was confirmed in-vitro. After treatment, GDF11 levels were significantly increased but there was no difference in heart weight (HW) to body weight (BW) ratio (4.74 vs 4.70) between GDF11 and vehicle treated old mice. HW/BW ratios of old mice were not different from12 week-old animals (4.56) and the PCH markers ANP and BNP were not different in young verses old mice. Before GDF11 treatment there were no significant differences in ejection fraction (46 versus 46 %), internal ventricular dimensions (4.33 vs 4.28 mm), and septal wall thickness (0.72 versus 0.78 mm) between GDF11 and vehicle treated groups. All structural and functional parameters remained unchanged at 1, 2 and 4 weeks of treatment. Strain analysis showed no significant difference in radial or longitudinal strain. Invasive hemodynamics performed at time of sacrifice also showed no significant differences in max dP/dt (6499.17 vs 6011.95 mmHg/s) or min dP/dt (-6551.73 vs -6214.33 mmHg/s) between GDF11 and vehicle treated animals respectively. Conclusions: There is no significant age-related PCH in C57Bl6 mice. GDF11 injections had no effects on cardiac structure or function in old male C57BL/6 mice. Our results question the idea that there is age-related PCH in disease free C57BL6 mice and question the findings that restoring GDF11 in old mice has any effect on cardiac structure or function.

Alteration of plasma gdf-11 levels in type 2 diabetes patients with cardiovascular complications: A pilot study

Background: Patients with type 2 diabetes mellitus (T2DM) have an increased risk of cardiovascular diseases. Scientific literature reported that growth differentiation factor-11 (GDF-11) has an important role to prevent aging of the heart and decreases with age. However, there is no study to look at plasma GDF-11 levels in diabetes and diabetes associated with cardiovascular complications in India. Therefore, the present study was designed to know the alteration of GDF-11 levels in Indian patients having diabetes and diabetes with cardiovascular complications. Methods: Plasma GDF-11 levels were measured from total 89 age-matched (35-65) subjects by ELISA method. All patients were divided into five groups; control (CT, n = 20), T2DM (n = 15), T2DM with hypertension (T2DM_HTN, n = 14), coronary artery disease (CAD, n = 20), and CAD with T2DM (T2DM_CAD, n = 20). Clinical parameters such as glycated haemoglobin A1c (HbA1c), fasting blood sugar, creatinine, lipid profile, uric acid, and systolic and diastolic blood pressure were measured in all the patients. Results: Plasma GDF-11 levels were measured in all the study groups. We have observed that GDF-11 levels were significantly decreased in T2DM, T2DM_HTN, CAD, and T2DM_CAD subjects compared to CT subjects. Our data indicated that plasma GDF-11 levels were inversely associated with age but did not show any correlation with fasting blood glucose and Hb1Ac levels. Conclusion: Plasma GDF-11 levels were decreased in Indian patients associated with diabetes and diabetes with cardiovascular complications. Further studies are required to understand the role of decreased plasma GDF-11 levels on disease progression and development of cardiovascular complications in diabetes.

Stem Cell Rejuvenation

Effective functioning of the body’s tissues and organs depends upon innate regenerative processes that maintain proper cell numbers during homeostasis and replace damaged cells after injury. In many tissues, regenerative potential is determined by the presence and functionality of dedicated populations of stem and progenitor cells, which respond to exogenous cues to produce replacement cells when needed. Understanding how these unspecialized precursors are maintained and regulated is essential for understanding the fundamental biology of tissues. In addition, this knowledge has practical implications, as stem cell regenerative potential can be exploited therapeutically by transplantation to replenish the stem cell pool or by pharmacological manipulation to boost the repair activity of cells already present in the tissue. Ongoing work in my laboratory focuses on defining how changes in stem cell activity impact tissue regeneration throughout life, and identifying physiological and pathological signals that modulate regenerative function in an age-dependent manner. Our recent data using parabiosis and transplantation models suggests that the circulatory system serves as a major source of such signals. In particular, exposure of aged tissues, including skeletal muscle, cardiac muscle and neural cells, to a “youthful” systemic environment appears to reverse many indicators of age-related pathology and restores robust regeneration following injury. While prior studies have identified a handful of systemic “aging” factors, discovery of the humoral “rejuvenating” factors that act on tissue stem cells to restore regenerative function has been relatively more elusive. In recent work, we identified that the circulating hormone Growth Differentiation Factor 11 (GDF11) is a rejuvenating factor for skeletal muscle and other tissues. Supplementation of systemic GDF11 levels, which normally decline with age in mice and humans, was sufficient to restore stem cell function in the skeletal muscle and other tissues, and improved physical function in aged mice. Taken together, these data reveal critical mechanisms in the regulation of aging by blood-borne factors and identify a promising therapeutic target candidate for the reversal of age-related tissue and stem cell dysfunction. Disclosures No relevant conflicts of interest to declare.

Systemic factors mediate reversible age-associated brain dysfunction.

Brain function declines in aging mammals. Recent work has identified dysregulation of key blood-borne factors whose altered expression during aging diminishes brain function in mice. Increased C-C motif chemokine 11 (CCL11) expression with aging is detrimental to brain function. On the other hand, plasma levels of the trophic factor growth/differentiation factor 11 (GDF11) decrease with aging. Restoration of youthful levels of GDF11 by injection partially restores brain function and neurogenesis by improving endothelial cell function and vasculature. Moreover, GDF11 has a rejuvenative effect on cardiac and skeletal muscle. Decreased type II interferon (IFN-II) and increased type I interferon (IFN-I) signaling during aging at the choroid plexus (CP), which constitutes the brain-cerebrospinal fluid barrier (B-CSF-B), negatively effects brain function. Blood from young mice contains factors that restore IFN-II levels. IFN-II is required for maintenance of the CP, and low IFN-II levels are associated with decreased cognitive abilities. IFN-I levels appear to drive increased CCL11 expression through the CSF. Blood from young animals does not restore IFN-I levels. However, injecting anti-interferon-α/β receptor (IFNAR) antibodies into the CSF inhibits downstream IFN-I gene and protein expression and decreases expression of CCL11, partially restoring neurogenesis and cognitive function. These results suggest that IFN-I plays a critical role in increasing CCL11 during aging of the brain. An emerging theme is that aging-associated loss of function in mammals may involve a set of defined, potentially reversible changes in many tissues and organs, including the brain, permitting development of potential rejuvenative therapies.

Modulation of Activin Signaling by RAP-011 (ActRIIA-IgG1) Improve Anemia, Increases Hemoglobin Levels and Corrects Ineffective Erythropoiesis in β-Thalassemia

AbstractAbstract 247 Background:β-thalassemia is associated with ineffective erythropoiesis, accelerated erythroid differentiation and apoptosis resulting in anemia and iron overload. The molecular mechanism involved is still incompletely understood. Members of the TGF-β superfamily participate in both proliferation and differentiation of erythroid progenitors. However, the role of these molecules in models of ineffective erythropoiesis has not been addressed so far. RAP-011 is a ligand trap consisting of the extracellular domain of ActRIIA linked to mouse IgG1 Fc domain. We aimed to study the role of ActRIIA signaling in the ineffective erythropoiesis of β-thalassemia and to evaluate the therapeutic impact of RAP-011. Methods:Hbbth1/th1 mice (a model of β-thalassemia intermedia) were subcutaneously treated with RAP-011 (10mg/kg body weight) twice a week for 30–60 days and biological and biochemical parameters were followed. Results:RAP-011 treatment significantly increased hemoglobin levels, red blood cell counts, MCV, MCH and hematocrit with a concomitant decrease in bilirubin levels and reticulocyte counts (since 10 days of treatment and sustained until day 60 of follow up). Flow cytometry analysis showed that RAP-011 significantly decreased late basophilic and polychromatic erythroblast cell numbers in both bone marrow and spleen indicating that RAP-011 corrects ineffective erythropoiesis. We next evaluated the expression of putative ActRIIA ligand(s) in β-thalassemia. Increased expression of Growth Differentiation Factor 11 (GDF11) was observed in cultured erythroblasts and in spleen sections of thalassemic mice. RAP-011 treatment decreased these elevated GDF11 levels in both bone marrow and spleen. We further investigated how BMP/Activin signaling was involved in ineffective erythropoiesis. Anti-GDF11 antibodies, follistatin (activin and GDF11 antagonist) and dorsomorphin (a small molecule inhibitor of SMAD1/5/8 phosphorylation) reduced differentiation, induced FAS-L expression and apoptosis in erythroblasts both in vivo and in vitro whereas noggin (a BMP-2/4 antagonist) had no effect on erythroblast differentiation. Altogether, these data suggest that Activin/BMP signaling controls erythroblast differentiation and targeting BMP type II /activin type II receptors can decrease ineffective erythropoiesis of β-thalassemia. Summary:Sotatercept (a humanized version of RAP-011) is currently in phase II clinical trials for treatment of anemia in patients with Myeloma Bone Disease and End Stage Renal Disease and data from our non-clinical findings support a newly initiated β-thalassemia clinical trial. Our results suggest that sotatercept would be a potential therapeutic tool to improve anemia, increase hemoglobin levels and correct ineffective erythropoiesis and its side effects in β-thalassemic patients. Disclosures:Daniel:Celgene Corporation: Employment. Chopra:Celgene Corp: Employment, Equity Ownership. Sung:Celgene: Employment.