Myostatin/Activin-A Signaling in the Vessel Wall and Vascular Calcification

Myostatin expression in lung cancer induces sarcopenia and promotes cancer progression

OBJECTIVES

Many studies have demonstrated that sarcopenia among lung cancer predicts poor prognosis due to cancer progression. However, the cytokines that link sarcopenia and lung cancer progression remain unidentified. This study aimed to investigate whether lung cancer producing myostatin, which induces skeletal muscle atrophy, leads to sarcopenia and promotes cancer progression in patients with resected lung cancer.

METHODS

Tumor tissues were obtained from 148 patients who underwent curative resection for lung cancer. Tumor cells were stained with myostatin and tumor-associated macrophages (TAM) in the tumor microenvironment were stained with CD68. We assessed the association between myostatin expression and the clinicopathological features.

RESULTS

High myostatin expression in lung cancer was significantly associated with low skeletal muscle mass. The 5-year overall survival and relapse-free survival were significantly worse among patients with high myostatin expression than those with low expression. A multivariate analysis showed that TAM count was positively correlated with high myostatin expression.

CONCLUSION

Sarcopenia may be induced by myostatin secreted by lung cancer cells. Moreover, myostatin may promote TAM migration into the tumor microenvironment, leading to advance lung cancer. As a result, patients with high myostatin expression had poor prognosis.

Circulating Myokines as Novel Biomarkers for Cardiovascular Diseases

Myokines are a group of cytokines or polypeptides released from skeletal muscle during exercise. Growing evidence suggests that myokines are associated with the development of cardiovascular disease (CVD). Moreover, several myokines in peripheral blood exhibit dynamic changes in different CVD stages. This review summarizes the potential roles of myokines such as myostatin, irisin, brain-derived neurotrophic factor, mitsugumin 53, meteorin-like, and apelin in various CVD, including myocardial infarction, heart failure, atherosclerosis, hypertension, and diabetes. The association of these myokines with biomarkers currently being used in clinical practice is also discussed. Furthermore, the review considers the emerging role of myokines in CVD and addresses the challenges remaining in translating these discoveries into novel clinical biomarkers for CVD.

Association of Serum Activin Levels with Allograft Outcomes in Patients with Kidney Transplant: Results from the KNOW-KT

INTRODUCTION

Serum activin A has been reported to contribute to vascular calcification and kidney fibrosis in chronic kidney disease. We aimed to investigate whether higher serum activin levels were associated with poor allograft outcomes in patients with kidney transplantation (KT).

METHODS

A total of 860 KT patients from KNOW-KT (Korean Cohort Study for Outcome in Patients with Kidney Transplantation) were analyzed. We measured serum activin levels pre-KT and 1 year after KT. The primary outcome was the composite of a ≥50% decline in estimated glomerular filtration rate and graft failure. Multivariable cause-specific hazard model was used to analyze association of 1-year activin levels with the primary outcome. The secondary outcome was coronary artery calcification score (CACS) at 5 years after KT.

RESULTS

During the median follow-up of 6.7 years, the primary outcome occurred in 109 (12.7%) patients. The serum activin levels at 1 year were significantly lower than those at pre-KT (488.2 ± 247.3 vs. 704.0 ± 349.6). When patients were grouped based on the median activin level at 1 year, the high-activin group had a 1.91-fold higher risk (95% CI, 1.25-2.91) for the primary outcome compared to the low-activin group. A one-standard deviation increase in activin levels as a continuous variable was associated with a 1.36-fold higher risk (95% CI, 1.16-1.60) for the primary outcome. Moreover, high activin levels were significantly associated with 1.56-fold higher CACS (95% CI, 1.12-2.18).

CONCLUSION

Post-transplant activin levels were independently associated with allograft functions as well as coronary artery calcification in KT patients.

Myostatin: a potential therapeutic target for metabolic syndrome

Metabolic syndrome is a complex metabolic disorder, its main clinical manifestations are obesity, hyperglycemia, hypertension and hyperlipidemia. Although metabolic syndrome has been the focus of research in recent decades, it has been proposed that the occurrence and development of metabolic syndrome is related to pathophysiological processes such as insulin resistance, adipose tissue dysfunction and chronic inflammation, but there is still a lack of favorable clinical prevention and treatment measures for metabolic syndrome. Multiple studies have shown that myostatin (MSTN), a member of the TGF-β family, is involved in the development and development of obesity, hyperlipidemia, diabetes, and hypertension (clinical manifestations of metabolic syndrome), and thus may be a potential therapeutic target for metabolic syndrome. In this review, we describe the transcriptional regulation and receptor binding pathway of MSTN, then introduce the role of MSTN in regulating mitochondrial function and autophagy, review the research progress of MSTN in metabolic syndrome. Finally summarize some MSTN inhibitors under clinical trial and proposed the use of MSTN inhibitor as a potential target for the treatment of metabolic syndrome.

Serum levels of Activin A: Marker of insulin resistance and cardiovascular risk in prediabetics

Background

A substantial proportion of health burden in diabetic individuals can be attributed to cardiovascular complications. The increasing risk of cardiovascular complications along the spectrum of dysglycemia warrants the need to devise novel markers for early assessment and management. Activin A is a multifunctional cytokine with an important role in glucose homeostasis and vascular diseases. It can thus serve as a guide for early identification of cardiovascular disease (CVD) risk in prediabetes.

Objective

The aim of the study was to measure serum levels of activin A in prediabetics, compare them with normoglycemic controls and find the correlation of activin A with markers of insulin resistance such as the homeostatic model assessment of insulin resistance (HOMA-IR).

Methods

Sixty prediabetic patients and similar age-, sex-, blood pressure-, and BMI-matched controls were recruited in the study. In both groups, serum levels of fasting blood glucose and post prandial glucose, glycated hemoglobin (HbA1c) and fasting insulin were measured. HOMA-IR values were calculated. Serum activin A levels were measured in both groups using ELISA. The obtained values were compared between the two groups.

Results

The median (IQR) of s. fasting insulin (mIU/L) in the case group was 15.3 (12.2-18.62) which was significantly higher than that in the control group, which was 6 (4.2-7.3). The median (IQR) of s. activin A (ng/mL) in the case group was 263.55 (227.18-279.56) which was significantly higher than that in the control group, which was 159.9 (150.73-178.75) (P < 0.001). There was a very strong positive correlation of s. activin A (ng/mL) with s. fasting insulin (mIU/L) and HOMA-IR (rho = 0.67 and 0.75, respectively, P < 0.001).

Conclusion

Activin A, if combined with other atherosclerotic markers, might improve the assessment of insulin resistance and cardiovascular risk in prediabetics and lead to focus on lifestyle modifications and preventive medical therapy, thereby contributing to the prevention of CVD-related mortality and morbidity in these patients.

Sotatercept analog suppresses inflammation to reverse experimental pulmonary arterial hypertension

Sotatercept is an activin receptor type IIA-Fc (ActRIIA-Fc) fusion protein that improves cardiopulmonary function in patients with pulmonary arterial hypertension (PAH) by selectively trapping activins and growth differentiation factors. However, the cellular and molecular mechanisms of ActRIIA-Fc action are incompletely understood. Here, we determined through genome-wide expression profiling that inflammatory and immune responses are prominently upregulated in the lungs of a Sugen-hypoxia rat model of severe angio-obliterative PAH, concordant with profiles observed in PAH patients. Therapeutic treatment with ActRIIA-Fc—but not with a vasodilator—strikingly reversed proinflammatory and proliferative gene expression profiles and normalized macrophage infiltration in diseased rodent lungs. Furthermore, ActRIIA-Fc normalized pulmonary macrophage infiltration and corrected cardiopulmonary structure and function in Bmpr2 haploinsufficient mice subjected to hypoxia, a model of heritable PAH. Three high-affinity ligands of ActRIIA-Fc each induced macrophage activation in vitro, and their combined immunoneutralization in PAH rats produced cardiopulmonary benefits comparable to those elicited by ActRIIA-Fc. Our results in complementary experimental and genetic models of PAH reveal therapeutic anti-inflammatory activities of ActRIIA-Fc that, together with its known anti-proliferative effects on vascular cell types, could underlie clinical activity of sotatercept as either monotherapy or add-on to current PAH therapies.

Therapeutic Approaches for Treating Pulmonary Arterial Hypertension by Correcting Imbalanced TGF-β Superfamily Signaling

Pulmonary arterial hypertension (PAH) is a rare disease characterized by high blood pressure in the pulmonary circulation driven by pathological remodeling of distal pulmonary arteries, leading typically to death by right ventricular failure. Available treatments improve physical activity and slow disease progression, but they act primarily as vasodilators and have limited effects on the biological cause of the disease—the uncontrolled proliferation of vascular endothelial and smooth muscle cells. Imbalanced signaling by the transforming growth factor-β (TGF-β) superfamily contributes extensively to dysregulated vascular cell proliferation in PAH, with overactive pro-proliferative SMAD2/3 signaling occurring alongside deficient anti-proliferative SMAD1/5/8 signaling. We review the TGF-β superfamily mechanisms underlying PAH pathogenesis, superfamily interactions with inflammation and mechanobiological forces, and therapeutic strategies under development that aim to restore SMAD signaling balance in the diseased pulmonary arterial vessels. These strategies could potentially reverse pulmonary arterial remodeling in PAH by targeting causative mechanisms and therefore hold significant promise for the PAH patient population.