Activin in Glucose Metabolism

Multiancestry exome sequencing reveals INHBE mutations associated with favorable fat distribution and protection from diabetes

Body fat distribution is a major, heritable risk factor for cardiometabolic disease, independent of overall adiposity. Using exome-sequencing in 618,375 individuals (including 160,058 non-Europeans) from the UK, Sweden and Mexico, we identify 16 genes associated with fat distribution at exome-wide significance. We show 6-fold larger effect for fat-distribution associated rare coding variants compared with fine-mapped common alleles, enrichment for genes expressed in adipose tissue and causal genes for partial lipodystrophies, and evidence of sex-dimorphism. We describe an association with favorable fat distribution (p = 1.8 × 10^-09), favorable metabolic profile and protection from type 2 diabetes (~28% lower odds; p = 0.004) for heterozygous protein-truncating mutations in INHBE, which encodes a circulating growth factor of the activin family, highly and specifically expressed in hepatocytes. Our results suggest that inhibin βE is a liver-expressed negative regulator of adipose storage whose blockade may be beneficial in fat distribution-associated metabolic disease.

Diabetes as a potential compounding factor in COVID-19-mediated male subfertility

Recent work indicates that male fertility is compromised by SARS-CoV-2 infection. Direct effects derive from the presence of viral entry receptors (ACE2 and/or CD147) on the surface of testicular cells, such as spermatocytes, Sertoli cells, and Leydig cells. Indirect effects on testis and concentrations of male reproductive hormones derive from (1) virus-stimulated inflammation; (2) viral-induced diabetes, and (3) an interaction between diabetes and inflammation that exacerbates the deleterious effect of each perturbation. Reproductive hormones affected include testosterone, luteinizing hormone, and follicle-stimulating hormone. Reduction of male fertility is also observed with other viral infections, but the global pandemic of COVID-19 makes demographic and public health implications of reduced male fertility of major concern, especially if it occurs in the absence of serious symptoms that would otherwise encourage vaccination. Clinical documentation of COVID-19-associated male subfertility is now warranted to obtain quantitative relationships between infection severity and subfertility; mechanistic studies using animal models may reveal ways to mitigate the problem. In the meantime, the possibility of subfertility due to COVID-19 should enter considerations of vaccine hesitancy by reproductive-age males.

HMEJ-mediated site-specific integration of a myostatin inhibitor increases skeletal muscle mass in porcine

As a robust antagonist of myostatin (MSTN), follistatin (FST) is an important regulator of skeletal muscle development, and the delivery of FST to muscle tissue represents a potential therapeutic strategy for muscular dystrophies. The N terminus and FSI domain of FST are the functional domains for MSTN binding. Here, we aimed to achieve site-specific integration of FSI-I-I, including the signal peptide, N terminus, and three FSI domains, into the last codon of the porcine MSTN gene using a homology-mediated end joining (HMEJ)-based strategy mediated by CRISPR-Cas9. Based on somatic cell nuclear transfer (SCNT) technology, we successfully obtained FSI-I-I knockin pigs. H&E staining of longissimus dorsi and gastrocnemius cross-sections showed larger myofiber sizes in FSI-I-I knockin pigs than in controls. Moreover, the Smad and Erk pathways were inhibited, whereas the PI3k/Akt pathway was activated in FSI-I-I knockin pigs. In addition, the levels of MyoD, Myf5, and MyoG transcription were upregulated while that of MRF4 was downregulated in FSI-I-I knockin pigs. These results indicate that the FSI-I-I gene mediates skeletal muscle hypertrophy through an MSTN-related signaling pathway and the expression of myogenic regulatory factors. Overall, FSI-I-I knockin pigs with hypertrophic muscle tissue hold great promise as a therapeutic model for human muscular dystrophies.

Metabolic regulation of activins in healthy individuals and in obese patients undergoing bariatric surgery

OBJECTIVE

Follistatin binds and inactivates activins, which are potent inhibitors of muscle growth and metabolism and are currently being developed for the treatment of obesity and type 2 diabetes (T2D). We have recently reported that follistatin is regulated by glucose (and not lipids) and can prospectively predict the metabolic improvements observed after bariatric surgery. We utilized novel assays herein to investigate whether activins are regulated by glucose or lipids, whether their circulating levels change after bariatric surgery and whether these changes are predictors of metabolic outcomes up to 12 months later.

DESIGN AND METHODS

Activin A, B, AB and their ratios to follistatin were measured in (a) healthy humans (n = 32) undergoing oral or intravenous lipid or glucose intake over 6 h, (b) morbidly obese individuals with or without type 2 diabetes undergoing three different types of bariatric surgery (gastric banding, Roux-en-Y bypass or sleeve gastrectomy) in two clinical studies (n = 14 for the first and n = 27 for the second study).

RESULTS

Glucose intake downregulates circulating activin A, B and AB, indicating the presence of a feedback loop. Activin A decreases (~30%), activin AB increases (~25%) and activin B does not change after bariatric surgery. The changes in activin AB and its ratio to follistatin 3 months after bariatric surgery can predict the BMI reduction and the improvement in insulin and HOMA-IR observed 6 months postoperatively.

CONCLUSION

Activins are implicated in glucose regulation in humans as part of a feedback loop with glucose or insulin and predict metabolic outcomes prospectively after bariatric surgery.

Effects of equine metabolic syndrome on inflammation and acute-phase markers in horses

Obesity and metabolic disorders are associated with systemic low-grade chronic inflammation, both in humans and animals. The aim of the study is to assess the effects of obesity and hyperinsulinemia on individual components of the acute-phase reaction in equine metabolic syndrome (EMS) horses. Eight mixed-breed EMS and six control, age-matched horses of both sexes were included in the study. Animals were classified as EMS or control based on the assessment of BCS, cresty neck score, and basal insulin >50 μU/mL and/or insulin responses to the oral sugar test (OST) >60 μU/mL. Peripheral venous blood was collected. The expression of proinflammatory cytokines, the concentration of circulating cytokines, and acute-phase proteins (serum amyloid A, C-reactive protein, haptoglobin, activin A, and procalcitonin) were measured. The data were analyzed using the Mann-Whitney test, whereas correlations were examined using Spearman's correlation coefficient. The tests were statistically significant if P ≤ 0.05. There were no differences in cytokine gene expression, circulating cytokine concentrations, or concentrations of acute-phase proteins between the EMS and the control groups. There was a strong correlation between the basal concentration of insulin and the serum concentrations of IL-6 (r = 0.71, P < 0.05). Activin A was positively correlated with post-OST insulin concentrations (r = 0.707, P = 0.05), indicating that this marker of inflammation could warrant further investigation in horses with EMS.

The Fight Against Obesity Escalates: New Drugs on the Horizon and Metabolic Implications

PURPOSE OF REVIEW

There is currently a steep rise in the global prevalence of obesity. Pharmaceutical therapy is a valuable component of conservative obesity therapy. Herein, medications currently in the phase of preclinical or clinical testing are reviewed, along with an overview of the mechanisms that regulate energy intake and expenditure. In addition, the current and potential future directions of obesity drug therapy are discussed.

RECENT FINDINGS

Although the current arsenal of obesity pharmacotherapy is limited, a considerable number of agents that exert their actions through a variety of pharmacodynamic targets and mechanisms are in the pipeline. This expansion shapes a potential near future of obesity conservative management, characterized by tailored combined therapeutic regimens, targeting not only weight loss but also improved overall health outcomes. The progress regarding the elucidation of the mechanisms which regulate the bodily energy equilibrium has led to medications which mimic hormonal adaptations that follow bariatric surgery, in the quest for a "Medical bypass." These, combined with agents which could increase energy expenditure, point to a brilliant future in the conservative treatment of obesity.

Activin and inhibin signaling: From regulation of physiology to involvement in the pathology of the female reproductive system

Activins and inhibins - comprising activin A, B, AB, C and E, and inhibin A and B isoforms - belong to the transforming growth factor beta (TGFβ) superfamily. They regulate several biological processes, including cellular proliferation, differentiation and invasiveness, to enhance the formation and functioning of many human tissues and organs. In this review, we have discussed the role of activin and inhibin signaling in the physiological and female-specific pathological events that occur in the female reproductive system. The up-to-date evidence indicates that these cytokines regulate germ cell development, follicular development, ovulation, uterine receptivity, decidualization and placentation through the activation of several signaling pathways; and that their dysregulated expression is involved in the pathogenesis and pathophysiology of the numerous diseases, including pregnancy complications, that disturb reproduction. Hence, some of the isoforms have been suggested as potential biomarkers and therapeutic targets for the management of some of these diseases. Tackling the research directions highlighted in this review will enhance a detailed comprehension and the clinical utility of these cytokines.

Novel ActRIIB ligand trap increases muscle mass and improves bone geometry in a mouse model of severe osteogenesis imperfecta

Osteogenesis imperfecta (OI) caused by mutations affecting the extracellular matrix protein collagen type I is characterized by fragile bones and low muscle mass and function. Activin A and myostatin, members of the TGF-β superfamily, play a key role in the control of muscle mass and in muscle-bone communication. Here we investigated activin A/myostatin signaling in a mouse model of severe dominant OI, Col1a1^Jrt/+mouse, and the effect of activin A/myostatin inhibition by a soluble activin receptor IIB receptor, ACE-2494, on bones and muscles in 8-week old mice. Compared to wild type mice, Col1a1^Jrt/+mice had elevated TGF-β signaling in bone and muscle tissue. ACE-2494 treatment of wild type mice resulted in significantly increased muscle mass, bone length, bone mass as well as improved bone mechanical properties. However, treatment of Col1a1^Jrt/+mice with ACE-2494 was associated with significant gain in muscle mass, significantly improved bone length and bone geometry, but no significant treatment effect was found on bone mass or bone mechanical properties. Thus, our data indicate that activin A/myostatin neutralizing antibody ACE-2494 is effective in stimulating muscle mass, bone length and diaphyseal bone growth but does not correct bone mass phenotype in a mouse model ofdominant OI.

ALK4-SMAD2/3-SMAD4 signaling mediates the activin A-induced suppression of PTX3 in human granulosa-lutein cells

As one of the members of the transforming growth factor-β (TGF-β) superfamily, activin A plays an important role in regulating follicular development and oocyte maturation. Pentraxin 3 (PTX3) is the key component that promotes the process of cumulus expansion during mammalian ovulation. At present, the regulation of PTX3 expression in human granulosa cells remains largely unknown. This study aimed to examine the effects of activin A on the expression of PTX3 in human granulosa-lutein (hGL) cells and to investigate the underlying molecular mechanisms. Using an established immortalized hGL cell line (SVOG) and primary hGL cells as study models, we demonstrated that activin A significantly increased the phosphorylation of SMAD2 and SMAD3, which suppressed the expression of PTX3 at both the mRNA and protein levels. Additionally, these effects induced by activin A were completely reversed by pretreatment with the TGF-β type I receptor inhibitor SB431542 and knockdown of ALK4. Furthermore, knockdown of SMAD2, SMAD3, or SMAD4 completely reversed the activin A-induced suppressive effects on PTX3 expression. Notably, the ChIP analyses demonstrated that phosphorylated SMADs could bind to human PTX3 promoter. Collectively, our results showed that the ALK4-SMAD2/3-SMAD4 signaling pathway most likely mediates the suppressive effect of activin A on PTX3 expression in hGL cells.

Association between serum activin A and metabolic syndrome in older adults: Potential of activin A as a biomarker of cardiometabolic disease

Cardiovascular disease imposes substantial burdens of morbidity and mortality that increase with population aging. Estimating cardiometabolic risk accurately and expediently is challenging, and no single biomarker is satisfactory; hence, we investigated the potential of serum activin A for this purpose. Study data were collected from 433 community-dwelling adults age ≥53 years from Yilan County, Taiwan. Data included: demographics and medical history; physical measurements (blood pressure, body mass index, waist circumference); comprehensive functional assessments (frailty, cognitive function, depressive symptoms, nutritional status); fasting blood biochemistry (glucose, high-density lipoprotein cholesterol, triglycerides, high-sensitivity C-reactive protein, insulin-like growth factor-1, activin A, stratified into high, medium and low tertiles, and others); and dual-energy X-ray absorptiometry. Metabolic syndrome was considered a proxy for overall cardiometabolic risk. Subjects mean age was 69.3 ± 9.2 years, 48.3% were males. Compared to women, men had higher systolic blood pressure, education levels, relative appendicular skeletal muscle mass, waist circumference, physical activity, walking speed, free androgen index, and levels of serum uric acid, alanine aminotransferase, and dehydroepiandrosterone sulfate. High activin A was significantly associated with age, relative appendicular skeletal muscle mass in both gender, waist circumference in women, current alcohol drinking, hypertension, and Charlson Comorbidity Index. There were dose-dependent relationships (low to high) between serum activin A and frailty, cognitive impairment, malnutrition, metabolic syndrome, uric acid, and high-sensitivity C-reactive protein. Logistic regression analyses showed older age, serum uric acid, and metabolic syndrome were significantly associated with medium and high activin-A status, whereas, skeletal muscle mass, insulin-like growth factor-1 and dehydroepiandrosterone sulphate were associated with high, but not medium, serum activin A. This discovery of a dose-dependent association between serum activin A levels, age, and metabolic syndrome, suggests activin A may be a biomarker of overall cardiometabolic risk; however, further studies are needed to evaluate its potential applications in assessing and managing cardiometabolic risk.

Inhibin βE (INHBE) is a possible insulin resistance-associated hepatokine identified by comprehensive gene expression analysis in human liver biopsy samples

The liver plays a major role in whole-body energy homeostasis by releasing secretory factors, termed hepatokines. To identify novel target genes associated with insulin resistance, we performed a comprehensive analysis of gene expression profiles using a DNA chip method in liver biopsy samples from humans with varying degrees of insulin resistance. Inhibin βE (INHBE) was identified as a novel putative hepatokine with hepatic gene expression that positively correlated with insulin resistance and body mass index in humans. Quantitative real time-PCR analysis also showed an increase in INHBE gene expression in independent liver samples from insulin-resistant human subjects. Additionally, Inhbe gene expression increased in the livers of db/db mice, a rodent model of type 2 diabetes. To preliminarily screen the role of Inhbe in vivo in whole-body energy metabolic status, hepatic mRNA was knocked down with siRNA for Inhbe (siINHBE) in db/db mice. Treatment with siINHBE suppressed body weight gain during the two-week experimental period, which was attributable to diminished fat rather than lean mass. Additionally, treatment with siINHBE decreased the respiratory quotient and increased plasma total ketone bodies compared with treatment with non-targeting siRNA, both of which suggest enhanced whole-body fat utilization. Our study suggests that INHBE functions as a possible hepatokine to alter the whole-body metabolic status under obese insulin-resistant conditions.

Follistatin N terminus differentially regulates muscle size and fat in vivo

Delivery of follistatin (FST) represents a promising strategy for both muscular dystrophies and diabetes, as FST is a robust antagonist of myostatin and activin, which are critical regulators of skeletal muscle and adipose tissues. FST is a multi-domain protein, and deciphering the function of different domains will facilitate novel designs for FST-based therapy. Our study aims to investigate the role of the N-terminal domain (ND) of FST in regulating muscle and fat mass in vivo. Different FST constructs were created and packaged into the adeno-associated viral vector (AAV). Overexpression of wild-type FST in normal mice greatly increased muscle mass while decreasing fat accumulation, whereas overexpression of an N terminus mutant or N terminus-deleted FST had no effect on muscle mass but moderately decreased fat mass. In contrast, FST-I-I containing the complete N terminus and double domain I without domain II and III had no effect on fat but increased skeletal muscle mass. The effects of different constructs on differentiated C2C12 myotubes were consistent with the in vivo finding. We hypothesized that ND was critical for myostatin blockade, mediating the increase in muscle mass, and was less pivotal for activin binding, which accounts for the decrease in the fat tissue. An in vitro TGF-beta1-responsive reporter assay revealed that FST-I-I and N terminus-mutated or -deleted FST showed differential responses to blockade of activin and myostatin. Our study provided direct in vivo evidence for a role of the ND of FST, shedding light on future potential molecular designs for FST-based gene therapy.

Hyperglycemia is associated with reduced testicular function and activin dysregulation in the Ins2Akita+/- mouse model of type 1 diabetes

Type 1 diabetes (T1D) is associated with subfertility in men. We hypothesised that this results from inhibitory effects of chronic hyperglycemia on testicular function and used the Ins2^Akita+/- mouse model to investigate this. Diabetic mice exhibited progressive testicular dysfunction, with a 30% reduction in testis weight at 24 weeks of age. Diabetic mice showed significantly reduced seminiferous tubule diameters and increased spermatogenic disruption, although testes morphology appeared grossly normal. Unexpectedly, serum LH and intra-testicular testosterone were similar in all groups. Ins2^Akita+/- mice displayed elevation of the testicular inflammatory cytokines activin A and IL-6. Intratesticular activin B was downregulated, while the activin regulatory proteins, follistatin and inhibin, were unchanged. Activin signalling, measured by pSmad3 and Smad4 production, was enhanced in diabetic mice only. These results suggest that prolonged exposure to hyperglycemia in the Ins2^Akita+/- mice leads to progressive testicular disruption mediated by testicular activin activity, rather than hormonal dysregulation.

Growth differentiation factor 15 is a myomitokine governing systemic energy homeostasis

Chung et al. show that the myomitokine GDF15 can act to modulate oxidative and lipolytic function in a non–cell-autonomous manner, thereby regulating systemic energy homeostasis in skeletal muscle-specific Crif1-deficient mice. This pathway may be a potential therapeutic target for preventing the onset of obesity and insulin resistance.

Reduced mitochondrial electron transport chain activity promotes longevity and improves energy homeostasis via cell-autonomous and –non-autonomous factors in multiple model systems. This mitohormetic effect is thought to involve the mitochondrial unfolded protein response (UPR^mt), an adaptive stress-response pathway activated by mitochondrial proteotoxic stress. Using mice with skeletal muscle–specific deficiency of Crif1 (muscle-specific knockout [MKO]), an integral protein of the large mitoribosomal subunit (39S), we identified growth differentiation factor 15 (GDF15) as a UPR^mt-associated cell–non-autonomous myomitokine that regulates systemic energy homeostasis. MKO mice were protected against obesity and sensitized to insulin, an effect associated with elevated GDF15 secretion after UPR^mt activation. In ob/ob mice, administration of recombinant GDF15 decreased body weight and improved insulin sensitivity, which was attributed to elevated oxidative metabolism and lipid mobilization in the liver, muscle, and adipose tissue. Thus, GDF15 is a potent mitohormetic signal that safeguards against the onset of obesity and insulin resistance.

Myocardial dysfunction and cardiovascular disease in type 2 diabetes

Type 2 diabetes mellitus (T2DM) is strongly associated with increased risk of myocardial dysfunction and cardiovascular disease (CVD), two separate conditions which often co-exist and influence each other's course. The prevalence of myocardial dysfunction may be as high as 75% in T2DM populations but is often overlooked due to the initial asymptomatic nature of the disease, complicating co-morbidities such as coronary artery disease (CAD) and obesity, and the lack of consensus on diagnostic criteria. More sensitive echocardiographic applications are furthermore needed to improve detection of early subclinical changes in myocardial function which do not affect conventional echocardiographic parameters. The pathophysiology of the diabetic myocardial dysfunction is not fully elucidated, but involves hyperglycemia and high levels of free fatty acids. It evolves over several years and increases the risk of developing overt HF, and is suggested to at least in part account for the worse outcome seen in T2DM individuals after cardiac events. CAD and stroke are the most frequent CV manifestations among T2DM patients and relate to a large degree to the accelerated atherosclerosis driven by inflammation. Diagnosing CAD is challenging due to the lower sensitivity inherent in the diagnostic tests and there is thus a need for new biomarkers to improve prediction and detection of CAD. It seems that a multi-factorial approach (i.e. targeting several CV risk factors simultaneously) is superior to a strict glucose lowering strategy in reducing risk for macrovascular events, and recent research may even support an effect also on HF outcomes.

Overcoming Insulin Insufficiency by Forced Follistatin Expression in β-cells of db/db Mice

Diabetes poses a substantial burden to society as it can lead to serious complications and premature death. The number of cases continues to increase worldwide. Two major causes of diabetes are insulin resistance and insulin insufficiency. Currently, there are few antidiabetic drugs available that can preserve or protect β-cell function to overcome insulin insufficiency in diabetes. We describe a therapeutic strategy to preserve β-cell function by overexpression of follistatin (FST) using an AAV vector (AAV8-Ins-FST) in diabetic mouse model. Overexpression of FST in the pancreas of db/db mouse increased β-cell islet mass, decreased fasting glucose level, alleviated diabetic symptoms, and essentially doubled lifespan of the treated mice. The observed islet enlargement was attributed to β-cell proliferation as a result of bioneutralization of myostatin and activin by FST. Overall, our study indicates overexpression of FST in the diabetic pancreas preserves β-cell function by promoting β-cell proliferation, opening up a new therapeutic avenue for the treatment of diabetes.

Effect of physical training on liver expression of activin A and follistatin in a nonalcoholic fatty liver disease model in rats

Nonalcoholic fatty liver disease (NAFLD) is characterized by fat accumulation in the liver and is associated with obesity and insulin resistance. Activin A is a member of the transforming growth factor beta (TGF)-β superfamily and inhibits hepatocyte growth. Follistatin antagonizes the biological actions of activin. Exercise is an important therapeutic strategy to reduce the metabolic effects of obesity. We evaluated the pattern of activin A and follistatin liver expression in obese rats subjected to swimming exercise. Control rats (C) and high-fat (HF) diet-fed rats were randomly assigned to a swimming training group (C-Swim and HF-Swim) or a sedentary group (C-Sed and HF-Sed). Activin βA subunit mRNA expression was significantly higher in HF-Swim than in HF-Sed rats. Follistatin mRNA expression was significantly lower in C-Swim and HF-Swim than in either C-Sed or HF-Sed animals. There was no evidence of steatosis or inflammation in C rats. In contrast, in HF animals the severity of steatosis ranged from grade 1 to grade 3. The extent of liver parenchyma damage was less in HF-Swim animals, with the severity of steatosis ranging from grade 0 to grade 1. These data showed that exercise may reduce the deleterious effects of a high-fat diet on the liver, suggesting that the local expression of activin-follistatin may be involved.

Follistatin and activins in polycystic ovary syndrome: relationship to metabolic and hormonal markers

OBJECTIVE

Polycystic ovary syndrome (PCOS) is common and has reproductive and metabolic manifestations. Activin A and follistatin levels remain controversial and activin B levels are unstudied in PCOS. The aim of this study was to evaluate activin A, activin B and follistatin levels and to examine their associations with metabolic status in overweight and obese women with and without PCOS.

MATERIALS AND METHODS

Cross-sectional study assessing overweight and obese, premenopausal women with PCOS (n=51, n=26 National Institutes of Health (NIH) and n=25 non-NIH) and without PCOS (n=25 controls). Outcomes included activin A, activin B, follistatin and activin A/follistatin ratio and the association of the activins and follistatin with metabolic variables.

RESULTS

Activin A, activin B and activin A/follistatin ratio were not significantly different and follistatin was elevated for PCOS versus controls (P=0.01) independent of age or BMI. Follistatin levels were significantly different across the PCOS phenotypes (p=0.05), however this was a non-significant trend (after correction for age and BMI) for women with NIH PCOS or non-NIH PCOS to have elevated levels in comparison to controls. Activin A was most strongly predicted by low density lipoprotein/high density lipoprotein (r(2)=0.192, p<0.001), follistatin by triglycerides and highly sensitive C-reactive protein (r(2)=0.340, p<0.001) and the activin A/follistatin ratio by insulin area under the curve and mean arterial pressure (r(2)=0.289, p<0.001).

CONCLUSIONS

Follistatin is elevated and activins A and B are not different between PCOS and controls. Follistatin and activin A are related to metabolic parameters in women with and without PCOS. Follistatin may potentially act as a marker of or be involved in the pathophysiology of both reproductive and metabolic features of PCOS.

Correlation between blood activin levels and clinical parameters of type 2 diabetes

Aims. Activins A and B, and their binding protein, follistatin, regulate glucose metabolism and inflammation. Consequently, their role in type 2 diabetes (T2D) was examined. Methods. Blood was taken from fasted participants (34 males; 58 females; 50–75 years) with diabetes or during an oral glucose tolerance test (OGTT). Clinical parameters were assessed, and blood assayed for activins, follistatin, and C-reactive protein. Results. Serum levels of activin A (93.3 ± 27.0 pg/mL, mean ± SD), B (81.8 ± 30.8 pg/mL), or follistatin (6.52 ± 3.15 ng/mL) were not different (P > 0.05) between subjects with normal OGTT (n = 39), impaired glucose tolerance and/or fasting glucose (n = 17), or T2D (n = 36). However, activin A and/or activin B were positively correlated with parameters of insulin resistance and T2D, including fasting glucose (P < 0.001), fasting insulin (P = 0.02), glycated hemoglobin (P = 0.003), and homeostasis model assessment of insulin resistance (HOMA-IR; P < 0.001). Follistatin was positively correlated with HOMA-IR alone (P = 0.01). Conclusions. These data indicate that serum measurements of activin A, B, or follistatin cannot discriminate risk for T2D in individual patients, but the activins display a positive relationship with clinical parameters of the disease.

Activin A and cardiovascular disease in type 2 diabetes mellitus

BACKGROUND

Silent coronary artery disease is a frequent complication of type 2 diabetes (T2DM). Based on its multiple roles in inflammation, atherogenesis and glucose homeostasis, we hypothesised that activin A could be related to coronary atherosclerosis in T2DM.

METHODS

Activin A and follistatin were measured in 102 patients with T2DM and 20 age- and sex-matched healthy controls. Coronary angiography was performed in a sub-population of patients and associations with activin A were examined using multiple linear regression.

RESULTS

Serum activin A and the activin A/follistatin ratio were increased in patients with T2DM and coronary artery disease (CAD) compared with healthy volunteers and the elevated activin A was associated with the severity of coronary atherosclerotic burden as determined by the proportion of ≥2 vessel disease (p = 0.035) after multivariable-adjusted trend analysis. No significant association between presence of CAD or extent score and activin A was observed.

CONCLUSION

In patients with T2DM, increased activin A may reflect chronic underlying pathophysiological processes involved in development of cardiovascular disease.