Effects of Age, Diabetes, and Vascular Disease on Growth Differentiation Factor 11: First-in-Human Study

Naringenin and β-carotene convert human white adipocytes to a beige phenotype and elevate hormone- stimulated lipolysis

Introduction

Naringenin, a peroxisome proliferator-activated receptor (PPAR) activator found in citrus fruits, upregulates markers of thermogenesis and insulin sensitivity in human adipose tissue. Our pharmacokinetics clinical trial demonstrated that naringenin is safe and bioavailable, and our case report showed that naringenin causes weight loss and improves insulin sensitivity. PPARs form heterodimers with retinoic-X-receptors (RXRs) at promoter elements of target genes. Retinoic acid is an RXR ligand metabolized from dietary carotenoids. The carotenoid β-carotene reduces adiposity and insulin resistance in clinical trials. Our goal was to examine if carotenoids strengthen the beneficial effects of naringenin on human adipocyte metabolism.

Methods

Human preadipocytes from donors with obesity were differentiated in culture and treated with 8µM naringenin + 2µM β-carotene (NRBC) for seven days. Candidate genes involved in thermogenesis and glucose metabolism were measured as well as hormone-stimulated lipolysis.

Results

We found that β-carotene acts synergistically with naringenin to boost UCP1 and glucose metabolism genes including GLUT4 and adiponectin, compared to naringenin alone. Protein levels of PPARα, PPARγ and PPARγ-coactivator-1α, key modulators of thermogenesis and insulin sensitivity, were also upregulated after treatment with NRBC. Transcriptome sequencing was conducted and the bioinformatics analyses of the data revealed that NRBC induced enzymes for several non-UCP1 pathways for energy expenditure including triglyceride cycling, creatine kinases, and Peptidase M20 Domain Containing 1 (PM20D1). A comprehensive analysis of changes in receptor expression showed that NRBC upregulated eight receptors that have been linked to lipolysis or thermogenesis including the β1-adrenergic receptor and the parathyroid hormone receptor. NRBC increased levels of triglyceride lipases and agonist-stimulated lipolysis in adipocytes. We observed that expression of RXRγ, an isoform of unknown function, was induced ten-fold after treatment with NRBC. We show that RXRγ is a coactivator bound to the immunoprecipitated PPARγ protein complex from white and beige human adipocytes.

Discussion

There is a need for obesity treatments that can be administered long-term without side effects. NRBC increases the abundance and lipolytic response of multiple receptors for hormones released after exercise and cold exposure. Lipolysis provides the fuel for thermogenesis, and these observations suggest that NRBC has therapeutic potential.

A Renewed Focus on GDF11 Level Fluctuation in Human Serum in Relation to Physical Examination Indicators

Growth and differentiation factor 11 (GDF11) is a member of the transforming growth factor β superfamily. Previous studies have shown that GDF11 decreases with age and has antiaging effects; however, such reports are controversial. We choose 152 subjects covering a large age range (2 hours to 75 years) to measure serum GDF11. Twenty-two hematological variables and 13 biochemical values were measured. Pearson's analysis found a significant correlation between GDF11 and age (p = .0000, r = .4898), as well as serum creatinine, uric acid, triglycerides, red blood cell count, hemoglobin, hematocrit, and platelet volume distribution width. GDF11 negatively correlated with aspartate transaminase, white blood cell count, platelet count, lymphocyte count, monocyte count, mean platelet volume, and plateletcrit. Interestingly, we found GDF11 increases in people aged 20-30 years, holds steady in people aged 30-50 years, and increases in people older than 50 years. The results suggest that GDF11 serves different roles along the life span. The current actual evidence supports that GDF11 is helpful to promote aging.

Serum growth differentiation factor 11 is closely related to metabolic syndrome in a Chinese cohort

AIMS/INTRODUCTION

Despite increasing interest in growth differentiation factor 11 (GDF11) based on its involvement in age-related disorders, clinical implications - especially for metabolic diseases - remain unclear. Therefore, we assessed the association between serum GDF11 levels and metabolic disturbance in the Chinese population.

MATERIALS AND METHODS

A total of 381 individuals from the Shanghai Nicheng Cohort Study were included. In addition to anthropometry, laboratory and ultrasonography measurements, serum concentrations of GDF11 were measured by enzyme-linked immunosorbent assay.

RESULTS

Circulating GDF11 concentrations were unchanged with age (r = -0.064, P = 0.210), but showed an inverse relationship to body mass index, waist circumference and fat-free mass index (all P < 0.05). Correlation analysis showed decreased GDF11 concentrations accompanied by elevated diastolic blood pressure, fasting and 2-h plasma glucose, triglycerides, and low-density lipoprotein cholesterol after adjusting for sex, age and body mass index, whereas variations in aspartate aminotransferase and free thyroxine were consistent with GDF11 (all P < 0.05). Furthermore, people, especially men, with abnormal glycometabolism, body mass index and/or fat accumulation in the liver had lower serum levels of GDF11 (P < 0.05); an increase in metabolic syndrome morbidity along with the circulatory decline of GDF11 was found when stratified by GDF11-level quartiles (P-trend <0.001). Logistic regression showed that serum GDF11 levels were independently correlated with the presence of metabolic syndrome (odds ratio 0.665, 95% confidence interval 0.510-0.867, P = 0.003).

CONCLUSIONS

We confirmed GDF11 as an endocrine factor playing a significant role in multiple metabolic processes and an indicator of metabolic syndrome in the Chinese population, particularly in males.

Circulating GDF11 levels are decreased with age but are unchanged with obesity and type 2 diabetes

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor β (TGFβ) superfamily which declines with age and exerts anti-aging regenerative effects in skeletal muscle in mice. However, recent data in humans and mice are conflicting casting doubts about its true functional actions. The aim of the present study was to compare the circulating concentrations of GDF11 in individuals of different ages as well as body weight and glycemic status. Serum concentrations of GDF11 were measured by ELISA in 319 subjects. There was a significant increase in GDF11 concentrations in people in the 41-50 y group and a decline in the elder groups (61-70 and 71-80 y groups, P=0.008 for the comparison between all age groups). However, no significant correlation between fat-free mass index (FFMI), a formula used to estimate the amount of muscle mass in relation to height, and logGDF11 was observed (r=0.08, P=0.197). Moreover, no significant differences in circulating concentrations of GDF11 regarding obesity or glycemic status were found. Serum GDF11 concentrations in humans decrease in older ages being unaltered in obesity and T2D. Further studies should determine the exact pathophysiological role of GDF11 in aging.

Growth differentiation factor-11 supplementation improves survival and promotes recovery after ischemic stroke in aged mice

Growth differentiation factor (GDF) 11 levels decline with aging. The age-related loss of GDF 11 has been implicated in the pathogenesis of a variety of age-related diseases. GDF11 supplementation reversed cardiac hypertrophy, bone loss, and pulmonary dysfunction in old mice, suggesting that GDF11 has a rejuvenating effect. Less is known about the potential of GDF11 to improve recovery after an acute injury, such as stroke, in aged mice. GDF11/8 levels were assessed in young and aged male mice and in postmortem human brain samples. Aged mice were subjected to a transient middle cerebral artery occlusion (MCAo). Five days after MCAo, mice received and bromodeoxyuridine / 5-Bromo-2'-deoxyuridine (BrdU) and either recombinant GDF11 or vehicle for five days and were assessed for recovery for one month following stroke. MRI was used to determine cerebrospinal fluid (CSF) volume, corpus callosum (CC) area, and brain atrophy at 30 days post-stroke. Immunohistochemistry was used to assess gliosis, neurogenesis, angiogenesis and synaptic density. Lower GDF11/8 levels were found with age in both mice and humans (p<0.05). GDF11 supplementation reduced mortality and improved sensorimotor deficits after stroke. Treatment also reduced brain atrophy and gliosis, increased angiogenesis, improved white matter integrity, and reduced inflammation after stroke. GDF11 may have a role in brain repair after ischemic injury.

Gdf11 gene transfer prevents high fat diet-induced obesity and improves metabolic homeostasis in obese and STZ-induced diabetic mice

Background

The growth differentiation factor 11 (GDF11) was shown to reverse age-related hypertrophy on cardiomyocytes and considered as anti-aging rejuvenation factor. The role of GDF11 in regulating metabolic homeostasis is unclear. In this study, we investigated the functions of GDF11 in regulating metabolic homeostasis and energy balance.

Methods

Using a hydrodynamic injection approach, plasmids carrying a mouse Gdf11 gene were delivered into mice and generated the sustained Gdf11 expression in the liver and its protein level in the blood. High fat diet (HFD)-induced obesity was employed to examine the impacts of Gdf11 gene transfer on HFD-induced adiposity, hyperglycemia, insulin resistance, and hepatic lipid accumulation. The impacts of GDF11 on metabolic homeostasis of obese and diabetic mice were examined using HFD-induced obese and STZ-induced diabetic models.

Results

Gdf11 gene transfer alleviates HFD-induced obesity, hyperglycemia, insulin resistance, and fatty liver development. In obese and STZ-induced diabetic mice, Gdf11 gene transfer restores glucose metabolism and improves insulin resistance. Mechanism study reveals that Gdf11 gene transfer increases the energy expenditure of mice, upregulates the expression of genes responsible for thermoregulation in brown adipose tissue, downregulates the expression of inflammatory genes in white adipose tissue and those involved in hepatic lipid and glucose metabolism. Overexpression of GDF11 also activates TGF-β/Smad2, PI3K/AKT/FoxO1, and AMPK signaling pathways in white adipose tissue.

Conclusions

These results demonstrate that GDF11 plays an important role in regulating metabolic homeostasis and energy balance and could be a target for pharmacological intervention to treat metabolic disease.

GDF11 antagonizes TNF-α-induced inflammation and protects against the development of inflammatory arthritis in mice

Growth differentiation factor 11 (GDF11), a key member of the TGF-β superfamily, plays critical roles in various medical conditions. Recently, GDF11 was found to suppress the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway and protect against inflammation. This study aimed to investigate the role of GDF11 in the development of rheumatoid arthritis (RA). We demonstrated that GDF11 treatment antagonized TNF-α-induced inflammation in macrophages. Moreover, GDF11 inhibited the development of arthritis in the collagen-induced arthritis and collagen antibody-induced arthritis models. Local gene transfer of GDF11 via adeno-associated virus exerted therapeutic effects, while local knockdown of GDF11 exaggerated inflammation in our collagen-induced arthritis model, as detected by expression levels of inflammatory biomarkers and the destruction of joint structures. Additionally, the results from both in vitro experiments and luciferase reporter gene mouse experiments implied that the NF-κB pathway might play a critical role in the therapeutic effect of GDF11 in RA. This study presents GDF11 as a potential target for the treatment of inflammatory arthritis, including RA.-Li, W., Wang, W., Liu, L., Qu, R., Chen, X., Qiu, C., Li, J., Hayball, J., Liu, L., Chen, J., Wang, X., Pan, X., Zhao, Y. GDF11 antagonizes TNF-α-induced inflammation and protects against the development of inflammatory arthritis in mice.

Role of growth differentiation factor 11 in development, physiology and disease

Growth differentiation factor (GDF11) is a member of TGF-β/BMP superfamily that activates Smad and non-Smad signaling pathways and regulates expression of its target nuclear genes. Since its discovery in 1999, studies have shown the involvement of GDF11 in normal physiological processes, such as embryonic development and erythropoiesis, as well as in the pathophysiology of aging, cardiovascular disease, diabetes mellitus, and cancer. In addition, there are contradictory reports regarding the role of GDF11 in aging, cardiovascular disease, diabetes mellitus, osteogenesis, skeletal muscle development, and neurogenesis. In this review, we describe the GDF11 signaling pathway and its potential role in development, physiology and disease.

GDF11 Protects against Endothelial Injury and Reduces Atherosclerotic Lesion Formation in Apolipoprotein E-Null Mice

Growth differentiation factor 11 (GDF11) reduces cardiac hypertrophy, improves cerebral vasculature and enhances neurogenesis in ageing mice. Higher growth differentiation factor 11/8 (GDF11/8) is associated with lower risk of cardiovascular events in humans. Here, we showed that adeno-associated viruses-GDF11 and recombinant GDF11 protein improve endothelial dysfunction, decrease endothelial apoptosis, and reduce inflammation, consequently decrease atherosclerotic plaques area in apolipoprotein E-/- mice. Moreover, adeno-associated viruses-GDF11 and recombinant GDF11 stabilize atherosclerotic plaques by selectively decreasing in macrophages and T lymphocytes, while increasing in collagen and vascular smooth muscle cells within plaques. In addition, GDF11 inhibit palmitic acid-induced endothelial apoptosis and ameliorate palmitic acid-induced inflammatory response in RAW264.7 macrophages in vitro. Mechanistically, GDF11 activates the TGF-β/Smad2/3, AMPK/endothelial nitricoxide synthase (eNOS) while suppresses JNK and NF-κB pathways. In humans, circulating GDF11/8 is positively associated with flow-mediated endothelium-dependent dilation in overweight subjects. We concluded that adeno-associated viruses-GDF11 and recombinant GDF11 protect against endothelial injury and reduce atherosclerosis in apolipoprotein E-/- mice, thus may be providing a novel approach to the treatment of atherosclerosis.

Protection against death and renal failure by renin-angiotensin system blockers in patients with diabetes and kidney disease

INTRODUCTION

Angiotensin-converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) are widely used to block the renin-angiotensin system (RAS). Yet it remains uncertain whether these drugs are equally effective and safe.

METHODS

Systematic reviews and meta-analyses of ACEis/ARBs in diabetes and kidney disease published in PubMed, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases were searched for clinical outcomes including all-cause mortality, end-stage renal disease (ESRD), hyperkalemia and cough.

RESULTS

Eight meta-analyses included 2177-61,264 patients with follow-up of 6-108 months. RAS blockers reduced mortality (relative risk ratio (RR), 0.90, 95% confidence interval (CI), 0.86-0.95) without heterogeneity. The death protection was significant specifically with ACEis (RR, 0.85, 95% CI, 0.79-0.91), but not with ARBs. Protection against ESRD was homogenously evident by ARBs (RR, 0.79, 95% CI, 0.73-0.87), ACEis (RR, 0.79, 95% , 0.64-0.94), and both (RR, 0.79, 95% CI, 0.73-0.87). Significant side effects were hyperkalemia by ARBs (RR, 2.44, 95% CI, 1.13-5.26), and cough by ACEis (RR, 2.38, 95% CI, 1.75-3.22) CONCLUSIONS: In patients with diabetes and kidney disease, ACEis and ARBs are consistently protective for the development of ESRD. Use of ACEis alone additionally reduces deaths and increases the risk for cough. Use of ARBs alone increases the risk for hyperkalemia without additional benefit of death protection.

Serum Levels of Growth Differentiation Factor 11 Are Independently Associated with Low Hemoglobin Values in Hemodialysis Patients

Circulating levels of growth differentiation factor 11 (GDF11) have been shown to decrease with age in several mammalian species, and supplementation of GDF11 by heterochronic parabiosis or systemic administration reverses age-related organ damage. However, there is some controversy about the pathophysiological role of GDF11 in aging-associated organ damage. Since aging process is accelerated in uremia, we compared serum levels of GDF11 in hemodialysis (HD) patients with those in age-matched healthy controls, and then determined the independent clinical correlates of GDF11 in HD subjects. Sixty-two maintenance HD patients (34 male and 28 female; mean age, 52.6 years; mean duration of HD, 7.7 months) were enrolled in the present study. Twenty-nine age-matched subjects were used as a control. GDF11 was measured by a commercially available enzyme-linked immunosorbent assay kit. Serum GDF11 levels in HD patients were significantly higher than those in controls (9.4 ± 5.1 pg/mL vs. 7.3 ± 5.9 pg/mL). A statistical significance was demonstrated between GDF11 and hemoglobin (inversely). Multiple stepwise regression analysis revealed that hemoglobin (p < 0.001) was a sole independent correlate of GDF11 levels in HD patients (R² = 0.168). Our present study suggests that kinetics and regulation of circulating GDF11 may differ between normal physiological aging process and accelerated pathological aging conditions, such as uremia. Given that GDF11 has been shown to inhibit erythroid maturation in mice, elevation of GDF11 levels may be involved in erythropoietin-resistant anemia in HD patients.