Angiotensin II inhibition: a potential treatment to slow the progression of sarcopenia

Chronic arsenite exposure induced skeletal muscle atrophy by disrupting angiotensin II-melatonin axis in rats

Arsenic is a well-known environmental toxicant and emerging evidence suggests that arsenic exposure has potential skeletal muscle toxicity; however, the underlying mechanism has not yet been clarified. The aim of this study was to investigate the correlation among adverse effects of subchronic and chronic environmental arsenic exposure on skeletal muscle as well as specific myokines secretion and angiotensin II (AngII)-melatonin (MT) axis in rats. Four-week-old rats were exposed to arsenite (iAs) in drinking water at environmental relevant concentration of 10 ppm for 3 or 9 months. Results indicated that the gastrocnemius muscle had atrophied and its mass was decreased in rats exposed to arsenite for 9 months, whereas, they had no significant changes in rats exposed to arsenite for 3 months. The levels of serum-specific myokine irisin and gastrocnemius muscle insulin-like growth factor-1 (IGF-1) were increased in 3-month exposure group and decreased in 9-month exposure group, while serum myostatin (MSTN) was increased significantly in 9-month exposure group. In addition, serum AngII level increased both in 3- and 9-month exposure groups, while serum MT level increased in 3-month exposure group and decreased in 9-month exposure group. Importantly, the ratio of AngII to MT level in serum increased gradually with the prolongation of arsenite exposure. It showed a certain correlation between AngII-MT axis and gastrocnemius muscle mass, gastrocnemius muscle level of IGF-1 or serum levels of irisin and MSTN. In conclusion, the disruption of AngII-MT axis balance may be a significant factor for skeletal muscle atrophy induced by chronic environmental arsenic exposure.

Angiotensin Receptor Blockers Restore Skeletal Muscle in Patients with Chronic Obstructive Pulmonary Disease

BACKGROUND

Age-related muscle decline, called sarcopenia, and hypertension are commonly observed in patients with chronic obstructive pulmonary disease (COPD). Angiotensin receptor blockers (ARBs) are common antihypertensive medications with muscle protective effects. However, the anti-sarcopenic potential and associated mechanisms of ARBs in hypertensive patients with COPD are unknown.

OBJECTIVES

We aimed to investigate the potential contribution of neuromuscular junction (NMJ) stability as a driving mechanism of ARBs-induced muscle protection.

METHODS

We categorized 236 patients with COPD into normotensive (n = 79) and hypertensive, based on treatment with ARB (n = 82), and other antihypertensive drugs (n = 75). Hypertensive patients with COPD were evaluated at two time points one year apart. Handgrip strength (HGS), body composition, short physical performance battery (SPPB), and plasma c-terminal agrin fragment-22 (CAF22) as a marker of NMJ degradation were measured.

RESULTS

Patients with COPD exhibited reduced HGS and SPPB scores, and higher levels of CAF22 than controls, regardless of hypertension status. ARBs treatment improved HGS and gait speed and reduced plasma CAF22 levels in hypertensive patients with COPD (all p <0.05). ARBs also prevented the decline in SPPB components, including maintaining balance, gait speed, and the ability to rise from a chair in hypertensive patients with COPD (all p <0.05). We also found dynamic associations of plasma CAF22 with HGS, gait speed, and SPPB scores in hypertensive patients with COPD.

CONCLUSIONS

Altogether, ARB treatment preserves skeletal muscle health and functional capacity in hypertensive patients with COPD by reducing plasma CAF22 and possibly repairing NMJs.

Comparison between bioelectrical impedance analyses and dual-energy X-ray absorptiometry for accuracy in assessing appendicular skeletal muscle mass and diagnosing sarcopenia in hospitalized Chinese older adults

The aim of this study was to compare bioelectrical impedance analysis (BIA) with dual-energy X-ray absorptiometry (DXA) and investigate the accuracy of BIA in assessing appendicular skeletal muscle mass (ASM) and diagnosing sarcopenia. A total of 90 elderly patients hospitalized in the Affiliated Hospital of Hangzhou Normal University from 2019 to 2020 were collected, including 42 males and 48 females. All patients underwent BIA and DXA examinations. Pearson correlation and Bland-Altman analysis were used to compare the differences between BIA and DXA in assessing ASM and diagnosing sarcopenia. ASM measured by BIA was higher than ASM measured by DXA, and there was statistical significance for all differences (P < .001); Pearson correlation analysis showed that ASM measured by BIA and DXA was positively correlated in both male (R = 0.94) and female (R = 0.97) patients (P < .001); Bland-Altman analysis showed that there was a high consistency between ASM detected by BIA and DXA; The detection rate of low muscle mass and sarcopenia by BIA and DXA was not statistically significant (P > .05). BIA (InBody720) has high accuracy in assessing ASM and diagnosing sarcopenia in hospitalized Chinese older adults, and has the advantages of convenient use, no radiation, and easy promotion, so it can be used as an early screening tool in primary hospitals lacking DXA.

ACE Inhibitors Improve Skeletal Muscle by Preserving Neuromuscular Junctions in Patients with Alzheimer's Disease

BACKGROUND

Hypertension and skeletal muscle decline are common findings in patients with Alzheimer's disease (AD). Angiotensin-converting enzyme (ACE) inhibitors preserve skeletal muscle and physical capacity; however, the driving mechanisms are poorly understood.

OBJECTIVE

We investigated the effects of ACE inhibitors on the neuromuscular junction (NMJ) with relevance to skeletal muscle and physical capacity in AD patients and age-matched controls.

METHODS

We evaluated controls (n = 59) and three groups of AD patients, including normotensive (n = 51) and patients with hypertension taking ACE inhibitors (n = 53) or other anti-hypertensive medications (n = 49) at baseline and one year later. We measure plasma c-terminal agrin fragment-22 (CAF22) as a marker of NMJ degradation, handgrip strength (HGS), and Short Physical Performance Battery (SPPB) as markers of physical capacity.

RESULTS

At baseline AD patients demonstrated lower HGS and SPPB scores and higher CAF22 levels than controls, irrespective of the hypertension status (all p < 0.05). The use of ACE inhibitors was associated with higher HGS and relative maintenance of SPPB scores, gait speed, and plasma CAF22 levels. Conversely, other anti-hypertensive medications were associated with an unaltered HGS, reduced SPPB scores and elevated plasma CAF22 levels (both p < 0.05). We also found dynamic associations of CAF22 with HGS, gait speed, and SPPB in AD patients taking ACE inhibitors (all p < 0.05). These changes were associated with reduced oxidative stress in AD patients taking ACE inhibitors (p < 0.05).

CONCLUSION

Altogether, ACE inhibitors are associated with higher HGS, preserved physical capacity, and the prevention of NMJ degradation in hypertensive AD patients.

Changes in aquaporins expression due to acute water restriction in naturally aging mice

Aquaporins (AQPs) are water channels in the cell membrane that regulate osmosis in response to rapid changes in intracellular and extracellular fluid concentration caused by extrinsic factors. While there are so many studies on the association of AQPs with muscular atrophy, sarcopenia, and Duchenne muscular dystrophy (DMD), the expression of AQP has not been verified in naturally aging mice or humans. Notably, due to the characteristics of AQPs, the difference in function cannot be evaluated without extrinsic factors such as acute water restriction. The purpose of this study was to investigate the changes in AQPs expression and function due to natural aging under acute water restriction conditions in aging mice. The expression of AQP4 was shown to decrease with aging similar to previous studies. However, for the first time, this study results confirmed that AQP1 expression increased in aging mice. In addition, the expression of Aqp1 decreased in the acute water restricted group compared to the control group after acute water restriction in aging mice. These results suggest that although the expression of AQP1 increases with aging, its function is reduced. We also confirmed that overexpression of Aqp1 can inhibit myotube differentiation and that knockdown can promote myotube differentiation through in vitro experiments. In conclusion, based on our results, we suggest that the AQP1 is an important factor in sarcopenia caused by natural aging accompanied by chronic dehydration.

Circulating miR-29b decrease in response to sarcopenia in patients with cardiovascular risk factors in older Chinese

Introduction

Sarcopenia is a clinical syndrome characterized by a progressive and extensive decline in skeletal muscle mass, muscle strength, and function. Sarcopenia and cardiovascular diseases (CVDs) can coexist, which further decreases the quality of life of patients, and increases the mortality rate. MicroRNAs (miRNAs) are unique posttranscriptional regulators of gene expression whose function in aging-related sarcopenia and CVDs has recently begun to unravel. The aim of the present study is to investigate the relationship between sarcopenia and cardiovascular risk factors (CVRF) in the Chinese elderly and describe the circulating miRNAs in sarcopenia patients with the intention of identifying novel diagnostic and therapeutic tools.

Methods

The well-established CVRF of diabetes, hypertension, and dyslipidemia were assessed. Multiple logistic regression analyses and linear regressions were used to evaluate the components of CVRF and the number of CVRF in elderly patients with sarcopenia. Moreover, we used real-time RT-PCR to measure the abundance of the CVRF-related miRNAs in the plasma of a cohort of 93 control and sarcopenia individuals, including miR-29b, miR-181a, and miR-494.

Results

We found that CVRF was associated with a high prevalence of sarcopenia in elderly Chinese populations After adjusting for potential confounders. Furthermore, hypertension and dyslipidemia, but not diabetes, were found to be significantly associated with sarcopenia. A linear increase in the prevalence of sarcopenia was found to be associated with the number of CVRF components in the elderly population. We found that plasma miR-29b levels were significantly down-regulated in response to sarcopenia in the elderly with CVRF. In particular, there was a remarkable correlation between miR-29b and appendicular skeletal muscle mass (ASM)/height2. Collectively, knowledge of CVRF, particularly hypertension and dyslipidemia, may help predict the risk of sarcopenia in the elderly. Our data also show that circulating miR-29b can be considered as possible biomarkers for sarcopenia, which may also be used in the CVD assessment of these patients.

Discussion

We found that the prevalence of sarcopenia was significantly proportional to the number of CVRF components. In particular, hypertension and dyslipidemia were significantly associated with a higher risk of sarcopenia in the adjusted models. Moreover, our study has been proven that c-miRNAs may be considered as possible biomarkers for sarcopenia as a new diagnostic tool to monitor response to treatment. There is also a pressing need for further research on sarcopenia and CVRF to understand their relationship and mechanism. These can provide more evidence to develop potential interventions to improve clinical outcomes.

The role of COVID-19 in myopathy: incidence, causes, treatment, and prevention

Myopathy is a disease characterized by muscle dysfunction in general and may be associated with genetics, medication such as statins, or inflammation. In 2019, an epidemic viral infection (SARS-CoV-2 virus) that invaded most countries worldwide appeared and caused acute respiratory disease. Consequently, patients had to take a group of drugs for a relatively long treatment period. According to several studies, there was an increase in the cases of muscular disorders due to several factors. This study aimed to (1) investigate the relationship between COVID-19 and myopathy and (2) identify the causes and prevention methods. A systematic review was conducted, analyzing several articles from the following databases: ResearchGate, Medline, DOAJ (The Directory of Open-Access Journals), PubMed, and Google Scholar. After performing the search and filtering the results, we included 61 articles. There was a strong relationship between COVID-19 and myopathy, especially in patients admitted to the ICU department, due to medication or neurological dysregulation with multiorgan dysfunctions such as polyneuropathy, peripheral nerve involvement, dysautonomia, Guillain-Barré syndrome, and many others.