Prediction of sarcopenia using a battery of circulating biomarkers

A leaky gut contributes to postural imbalance in male patients with chronic obstructive pulmonary disease

AIMS

Patients with chronic obstructive pulmonary disease (COPD) frequently exhibit an inability to maintain postural balance. However, the contribution of increased intestinal permeability or leaky gut to the postural imbalance in COPD is not known.

METHODS

We measured plasma zonulin, a marker of leaky gut, with relevance to postural balance in male controls (n = 70) and patients with mild (n = 67), moderate (n = 66), and severe (n = 58) COPD. We employed a short physical performance battery to evaluate postural balance in supine, tandem, and semi-tandem positions. We also measured handgrip strength (HGS), gait speed, plasma c-reactive proteins (CRP), and 8-isoprostanes as potential mechanistic connections between postural imbalance and leaky gut.

RESULTS

COPD patients demonstrated higher plasma zonulin, CRP, and 8-isoprostanes levels and lower balance, HGS, and gait speed than controls (all p < 0.05). These findings were more robust in patients with moderate and severe than mild COPD. In addition, plasma zonulin exhibited significant potential in diagnosing poor balance, low HGS, and gait speed in COPD patients (all p < 0.05). We also found significant correlations of plasma zonulin with CRP and 8-isoprostanes, providing heightened inflammation and oxidative stress as mechanistic connections between leaky gut and postural imbalance.

CONCLUSION

Plasma zonulin may be helpful in evaluating postural imbalance in COPD patients. Repairing intestinal leaks can be a therapeutic target to improve postural control in COPD.

The Global Research Trends on Intrinsic Capacity of Older Adults: A Bibliometric and Visual Analysis of Papers Published During 2015-2023

Objective

The concept of intrinsic capacity (IC) revolves around healthy aging and active aging. Since the Introduction of the concept by the World Health Organization in 2015, a series of studies have been conducted by scholars from multiple fields. However, no bibliometric analysis has systematically investigated this issue. We aim to identify the current landscape and frontier trends of scientific achievements on IC in older adults through bibliometric approaches.

Methods

Quantitative analysis of publications relating to IC in older adults from 2015 to 2023 was interpreted and graphed through the Web of Science Core Collection database on December 5, 2023. A variety of quantitative variables was analyzed, including publication and citation counts, H-index, and journal citation reports. Co-authorship, citation, co-citation, and co-occurrence analyses were performed for countries/regions, institutions, authors, and keywords using the VOSviewer and CiteSpace.

Results

A total of 952 original and review articles in English were identified. The European countries possessed an absolute advantage in this field. The most contributive institution was the University of São Paulo. The most productive author is Cesari Matteo from France, followed by Qaisar Rizwan from the United Arab Emirates. However, a relatively low level of research cooperation existed between institutions and authors. Important topics mainly include the connotations, theoretical framework models, evaluation, screening tools, and application scenarios of IC. Among the promising hotspots, "biological aging", "ICOPE", "Covid-19", "prevention", "inflammation", "caf22", "prevalence", and "randomized controlled trial" displayed relatively latest average appearing year.

Conclusion

Global trends indicate a growing scientific output on IC in older adults, and developed countries are leading the way. There is still room for improvement in research team collaboration. The focus gradually shifts from theoretical research to empirical research. It is recommended to pay attention to the latest hot spots, such as "biological aging", "ICOPE implementation", "post-COVID-19 syndrome", and "biomarkers".

Longitudinal Assessment of Blood-Based Inflammatory, Neuromuscular, and Neurovascular Biomarker Profiles in Intensive Care Unit-Acquired Weakness: A Prospective Single-Center Cohort Study

BACKGROUND

The diagnosis of intensive care unit (ICU)-acquired weakness (ICUAW) and critical illness neuromyopathy (CINM) is frequently hampered in the clinical routine. We evaluated a novel panel of blood-based inflammatory, neuromuscular, and neurovascular biomarkers as an alternative diagnostic approach for ICUAW and CINM.

METHODS

Patients admitted to the ICU with a Sequential Organ Failure Assessment score of ≥ 8 on 3 consecutive days within the first 5 days as well as healthy controls were enrolled. The Medical Research Council Sum Score (MRCSS) was calculated, and motor and sensory electroneurography (ENG) for assessment of peripheral nerve function were performed at days 3 and 10. ICUAW was defined by an MRCSS < 48 and CINM by pathological ENG alterations, both at day 10. Blood samples were taken at days 3, 10, and 17 for quantitative analysis of 18 different biomarkers (white blood cell count, C-reactive protein, procalcitonin, C-terminal agrin filament, fatty-acid-binding protein 3, growth and differentiation factor 15, syndecan 1, troponin I, interferon-γ, tumor necrosis factor-α, interleukin-1α [IL-1α], IL-1β, IL-4, IL-6, IL-8, IL-10, IL-13, and monocyte chemoattractant protein 1). Results of the biomarker analysis were categorized according to the ICUAW and CINM status. Clinical outcome was assessed after 3 months.

RESULTS

Between October 2016 and December 2018, 38 critically ill patients, grouped into ICUAW (18 with and 20 without) and CINM (18 with and 17 without), as well as ten healthy volunteers were included. Biomarkers were significantly elevated in critically ill patients compared to healthy controls and correlated with disease severity and 3-month outcome parameters. However, none of the biomarkers enabled discrimination of patients with and without neuromuscular impairment, irrespective of applied classification.

CONCLUSIONS

Blood-based biomarkers are generally elevated in ICU patients but do not identify patients with ICUAW or CINM.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02706314.

Tracking the Plasma C-Terminal Agrin Fragment as a Biomarker of Neuromuscular Decline in 18- to 87-Year-Old Men

OBJECTIVES

Plasma C-terminal agrin-fragment-22 (CAF22), a breakdown product of neuromuscular junction, is a potential biomarker of muscle loss. However, its levels from adolescence to octogenarians are unknown.

METHODS

We evaluated young (18-34 years, n = 203), middle-aged (35-59 years, n = 163), and old men (60-87 years, n = 143) for CAF22, handgrip strength (HGS), appendicular skeletal-mass index (ASMI), and gait speed.

RESULTS

We found an age-associated increase in CAF22 from young (100.9 ± 29 pmol) to middle-aged (128.3 ± 38.7 pmol) and older men (171.5 ± 35.5 pmol) (all p<0.05). This was accompanied by a gradual reduction in HGS (37.7 ± 6.1 kg, 30.2 ± 5.2 kg, and 26.6 ± 4.7 kg, for young, middle-aged, and old men, respectively), ASMI (8.02 ± 1.02 kg/m2, 7.65 ± 0.92 kg/m2, 6.87 ± 0.93 kg/m2, for young, middle-aged, and old men, respectively), and gait speed (1.29 ± 0.24 m/s, 1.05 ± 0.16 m/s, and 0.81 ± 0.13 m/s, for young, middle-aged, and old men, respectively). After adjustment for age, we found negative regressions of CAF22 with HGS (- 0.0574, p < 0.001) and gait speed (- 0.0162, p < 0.001) in the cumulative cohort. The receiver operating characteristics analysis revealed significant efficacy of plasma CAF22 in diagnosing muscle weakness (HGS < 27 kg) (middle-aged men; AUC = 0.731, 95% CI = 0.629-0.831, p < 0.001, Older men; AUC = 0.816, 95% CI = 0.761-0.833, p < 0.001), and low gait speed (0.8 m/s) (middle-aged men; AUC = 0.737, 95% CI = 0.602-0.871, p < 0.001, older men; AUC = 0.829, 95% CI = 0.772-0.886, p < 0.001), and a modest efficacy in diagnosing sarcopenia (middle-aged men; AUC = 0.701, 95% CI = 0.536-0.865, p = 0.032, older men; AUC = 0.822, 95% CI = 0.759-0.884, p < 0.001) in middle-aged and older men.

CONCLUSION

Altogether, CAF22 increases with advancing age and may be a reliable marker of muscle weakness and low gait speed.

Circulating myostatin as a biomarker of muscle mass and strength in individuals with cancer or obesity

BACKGROUND & AIMS

Our study aims to determine whether myostatin (MSTN) is associated with muscle mass and strength in individuals with cancer or obesity, as well as with cancer cachexia (CC) or sarcopenic obesity (SO).

METHODS

The ACTICA study included individuals with CC (n = 70) or without CC (NC, n = 73). The MYDIASECRET study included individuals with obesity evaluated before (T0) and 3 months (T3) after bariatric surgery (n = 62). Body composition was assessed using bioelectrical impedance analysis (BIA). Skeletal muscle mass (SMM) and appendicular SMM (ASMM) were calculated from Janssen's and Sergi's equations, respectively, and expressed as indexes (SMMI and ASMMI). Handgrip strength (HGS) was assessed using a Jamar hand-held dynamometer. MSTN plasma levels were measured using ELISA. Spearman's coefficient was used to correlate MSTN with muscle mass and strength. Receiver operating characteristic (ROC) curve analysis was performed to identify an optimal MSTN cutoff level for the prediction of CC or SO.

RESULTS

In the ACTICA study, muscle mass and strength were lower in CC individuals than in NC individuals (SMMI: 8.0 kg/m2vs 9.0 kg/m2, p = 0.004; ASMMI: 6.2 kg/m2vs 7.2 kg/m2, p < 0.001; HGS: 28 kg vs 38 kg, p < 0.001). MSTN was also lower in CC individuals than in NC individuals (1434 pg/mL vs 2149 pg/mL, p < 0.001). Muscle mass and strength were positively correlated with MSTN (SMMI: R = 0.500, p < 0.001; ASMMI: R = 0.479, p < 0.001; HGS: R = 0.495, p < 0.001). ROC curve analysis showed a MSTN cutoff level of 1548 pg/mL (AUC 0.684, sensitivity 57%, specificity 75%, p < 0.001) for the prediction of CC. In the MYDIASECRET study, muscle mass and strength were reduced at T3 (SMMI: -8%, p < 0.001; ASMMI: -12%, p < 0.001; HGS: -6%, p = 0.005). MSTN was also reduced at T3 (1773 pg/mL vs 2582 pg/mL, p < 0.001). Muscle mass and strength were positively correlated with MSTN at T0 and T3 (SMMI-T0: R = 0.388, p = 0.002; SMMI-T3: R = 0.435, p < 0.001; HGS-T0: R = 0.337, p = 0.007; HGS-T3: R = 0.313, p = 0.013). ROC curve analysis showed a MSTN cutoff level of 4225 pg/mL (AUC 0.835, sensitivity 98%, specificity 100%, p = 0.014) for the prediction of SO at T3.

CONCLUSIONS

MSTN is positively correlated with muscle mass and strength in individuals with cancer or obesity, suggesting its potential use as a biomarker of muscle mass and strength. The ROC curve analysis suggests the potential use of MSTN as a screening tool for CC and SO.

Plasma levels of Neurofilament light chain correlate with handgrip strength and sarcopenia in patients with chronic obstructive pulmonary disease

BACKGROUND

Age-associated muscle decline, termed sarcopenia, is a common systemic effect of chronic obstructive pulmonary disease (COPD). Circulating Neurofilament light chain (NfL) levels reflect neuronal degradation and may be relevant to sarcopenia phenotype. However, such an association in COPD patients remains elusive.

METHODS

We investigated male, 60-76 years old controls (n = 50) and COPD patients (n = 139) for plasma NfL levels in relation to sarcopenia and physical capacity markers. We measured handgrip strength (HGS), body composition, and short physical performance battery (SPPB) to evaluate sarcopenia and physical capacity.

RESULTS

COPD patients had higher plasma NfL and lower HGS and SPPB performance than controls. Plasma NfL levels demonstrated negative associations with HGS and gait speed in COPD patients (all p < 0.05). Further, NfL levels were negatively associated with total SPPB scores in controls and patients with advanced COPD (p < 0.05). Plasma NfL also demonstrated an acceptable accuracy in diagnosing sarcopenia in controls (AUC = 0.757, p < 0.05) and COPD (AUC = 0.806, p < 0.05) patients.

CONCLUSION

Collectively, plasma NfL may be helpful in evaluating sarcopenia phenotype and physical capacity in geriatric patients with COPD.

Resistance Exercise Reduces Sarcopenia by Repairing Leaky Gut in Patients with Alzheimer's Disease

PURPOSE

Sarcopenia or age-associated muscle loss is common in patients with Alzheimer's disease (AD). We have previously demonstrated the contribution of a leaky gut to sarcopenia in AD. Here, we asked whether resistant exercise (RE) reduces the sarcopenia phenotype by repairing intestinal leakage in patients with AD.

METHOD

A prospective, single-center study of older adults, including healthy controls and patients with AD (n = 44-51/group), was conducted to measure plasma zonulin and claudin-3 (markers of intestinal leakage), handgrip strength (HGS), and short physical performance battery (SPPB) as a measure of functional capacity. Measurements in patients with AD were performed at baseline and after 12 weeks of RE.

RESULTS

At baseline, patients with AD had higher plasma zonulin and claudin-3 and lower HGS, gait speed, and SPPB scores than controls. RE reduced plasma zonulin and claudin-3 levels and improved HGS, SPPB scores, and gait speed. Regression analysis revealed robust relationships between changes in plasma zonulin and claudin-3 with HGS. Plasma zonulin was also positively associated with SPPB scores. In addition, RE downregulated plasma markers of inflammation and oxidative stress. However, the prevalence of sarcopenia based on low HGS and muscle atrophy or low SPPB was not affected by RE.

CONCLUSION

Taken together, disruption of the intestinal mucosal barrier may contribute to functional decline and sarcopenia in AD, which is incompletely recovered by RE. Circulating levels of zonulin and claudin-3 may be valuable in predicting sarcopenia and functional capacity in older adults with AD.

Bone turnover markers and muscle decay indicator in patients with proximal femur fracture - a case-control study

Introduction

Fracture of the proximal femur is common in elderly patients, in fact threatening their lives. Age-related sarcopenia may be involved in the imbalance resulting in the injury. Handy and readily accessible biochemical tests would be useful to assess the musculoskeletal system condition in daily practice. The aim of the study was to determine whether there is any relation between muscle decay and fracture of the proximal femur and to assess bone quality in elderly patients.

Material and methods

In the study 22 patients who represented the treatment group were hospitalized due to proximal femur fracture. Eighteen patients from the control group with no fracture in their history were admitted to the Internal Medicine Department. Anyone treated for osteoporosis, immune disease affecting protein balance, neoplasm, mental illness, heart failure, or myocardial infarction was excluded from the study. In every case a blood sample from an elbow vein was drawn, collected in EDTA-K2 tubes, and then centrifuged to separate plasma from the whole blood. Subsequently, the concentrations of C-terminal cross-linked telopeptide of type I collagen (CTX-I), sex hormone binding globulin (SHBG) and creatine kinase (CK) in plasma were determined using commercial enzyme-linked immunosorbent assays.

Results

The CK plasma concentration differed between the patient groups (p = 0.011). The SHBG plasma concentration was significantly higher in the treatment group (p = 0.006), whereas a slight difference in CTX-I plasma concentration between the groups was found (p = 0.038). No significant correlations between plasma CK, SHBG or CTX-I were found (p > 0.05).

Conclusions

Creatine kinase is actually not an appropriate marker for the clinical assessment of muscle tissue quality in patients with or at risk of proximal femur fracture. Analyzing the quality of bone tissue, we can conclude it was poorer in patients with proximal femur fracture than in the control group.

Expression of intramuscular extracellular matrix proteins in vastus lateralis muscle fibres between atrophic and non-atrophic COPD

Background

Extracellular matrix (ECM) proteins are the major constituents of the muscle cell micro-environment, imparting instructive signalling, steering cell behaviour and controlling muscle regeneration. ECM remodelling is among the most affected signalling pathways in COPD and aged muscle. As a fraction of COPD patients present muscle atrophy, we questioned whether ECM composition would be altered in patients with peripheral muscle wasting (atrophic COPD) compared to those without muscle wasting (non-atrophic COPD).

Methods

A set of ECM molecules with known impact on myogenesis were quantified in vastus lateralis muscle biopsies from 29 COPD patients (forced expiratory volume in 1 s 55±12% predicted) using ELISA and real-time PCR. COPD patients were grouped to atrophic or non-atrophic based on fat-free mass index (<17 or ≥17 kg·m-2).

Results

Atrophic COPD patients presented a lower average vastus lateralis muscle fibre cross-sectional area (3872±258 μm2) compared to non-atrophic COPD (4509±198 μm2). Gene expression of ECM molecules was found significantly lower in atrophic COPD compared to non-atrophic COPD for collagen type I alpha 1 chain (COL1A1), fibronectin (FN1), tenascin C (TNC) and biglycan (BGN). In terms of protein levels, there were no significant differences between the two COPD cohorts for any of the ECM molecules tested.

Conclusions

Although atrophic COPD presented decreased contractile muscle tissue, the differences in ECM mRNA expression between atrophic and non-atrophic COPD were not translated at the protein level, potentially indicating an accumulation of long-lived ECM proteins and dysregulated proteostasis, as is typically observed during deconditioning and ageing.

Irisin and Its Role in Postmenopausal Osteoporosis and Sarcopenia

Menopause, an extremely delicate phase in a woman's life, is characterized by a drop in estrogen levels. This decrease has been associated with the onset of several diseases, including postmenopausal osteoporosis and sarcopenia, which often coexist in the same person, leading to an increased risk of fractures, morbidity, and mortality. To date, there are no approved pharmacological treatments for sarcopenia, while not all of those approved for postmenopausal osteoporosis are beneficial to muscles. In recent years, research has focused on the field of myokines, cytokines, or peptides secreted by skeletal muscle fibers following exercise. Among these, irisin has attracted great interest as it possesses myogenic properties but at the same time exerts anabolic effects on bone and could therefore represent the link between muscle and bone. Therefore, irisin could represent a new therapeutic strategy for the treatment of osteoporosis and also serve as a new biomarker of sarcopenia, thus facilitating diagnosis and pharmacological intervention. The purpose of this review is to provide an updated summary of what we know about the role of irisin in postmenopausal osteoporosis and sarcopenia.

The sGCa Vericiguat Exhibit Cardioprotective and Anti-Sarcopenic Effects through NLRP-3 Pathways: Potential Benefits for Anthracycline-Treated Cancer Patients

Anthracycline-induced cardiomyopathies and sarcopenia are frequently seen in cancer patients, affecting their overall survival and quality of life; therefore, new cardioprotective and anti-sarcopenic strategies are needed. Vericiguat is a new oral guanylate cyclase activator that reduces heart failure hospitalizations or cardiovascular death. This study highlighted the potential cardioprotective and anti-sarcopenic properties of vericiguat during anthracycline therapy. Human cardiomyocytes and primary skeletal muscle cells were exposed to doxorubicin (DOXO) with or without a pre-treatment with vericiguat. Mitochondrial cell viability, LDH, and Cytochrome C release were performed to study cytoprotective properties. Intracellular Ca++ content, TUNEL assay, cGMP, NLRP-3, Myd-88, and cytokine intracellular levels were quantified through colorimetric and selective ELISA methods. Vericiguat exerts significant cytoprotective and anti-apoptotic effects during exposure to doxorubicin. A drastic increase in cGMP expression and reduction in NLRP-3, MyD-88 levels were also seen in Vericiguat-DOXO groups vs. DOXO groups (p < 0.001) in both cardiomyocytes and human muscle cells. GCa vericiguat reduces cytokines and chemokines involved in heart failure and sarcopenia. The findings that emerged from this study could provide the rationale for further preclinical and clinical investigations aimed at reducing anthracycline cardiotoxicity and sarcopenia in cancer patients.

The geriatric nutrition risk index is longitudinally associated with incident Sarcopenia: evidence from a 5-year prospective cohort

BACKGROUND

Previous studies investigating the association between the geriatric nutrition risk index (GNRI) and sarcopenia either lacked longitudinal evidence or narrowly focused on specific populations.

AIMS

We aimed to reveal longitudinal associations of GNRI with sarcopenia risk in community-dwelling Chinese. We also investigated interaction effects of potential factors on such associations.

METHODS

We included participants aged ≥ 50 years with sufficient data from the WCHAT study who did not have sarcopenia at baseline and completed sarcopenia assessment during follow-up. GNRI was calculated according to the formula based on serum albumin, height and weight. Sarcopenia was diagnosed according to the 2019 AWGS consensus. Longitudinal associations between GNRI and sarcopenia were estimated by logistic regression with GNRI as either a continuous or categorical variable by tertiles, using generalized estimating equations (GEE) as sensitivity analyses. Subgroup analyses by potential covariates were conducted to detect interaction effects.

RESULTS

A total of 1907 participants without baseline sarcopenia were finally included, of whom 327 (17.1%) developed incident sarcopenia during 5-year follow-up. After controlling for confounders, sarcopenia risk decreased with each one standard deviation increase in GNRI (ORadjusted=0.36, 95% CI 0.31-0.43), and it also decreased successively from the lowest (< 111.2) through middle (111.2-117.7) to the highest (≥ 117.8) tertile of the GNRI level (P for trend < 0.001). Similar results were yielded by GEE. Such associations generally remained robust across subgroups with distinct characteristics, while significant differences were observed between different age groups (≥ 65 vs. <65 years) (interaction P-value < 0.05).

CONCLUSION

GNRI is longitudinally associated with sarcopenia risk with possibly age-specific differences in association magnitude, which holds implications for policymakers to conduct population-based risk assessment.

Proteomics and Machine Learning in the Prediction and Explanation of Low Pectoralis Muscle Area

Low muscle mass is associated with numerous adverse outcomes independent of other associated comorbid diseases. We aimed to predict and understand an individual's risk for developing low muscle mass using proteomics and machine learning. We identified 8 biomarkers associated with low pectoralis muscle area (PMA). We built 3 random forest classification models that used either clinical measures, feature selected biomarkers, or both to predict development of low PMA. The area under the receiver operating characteristic curve for each model was: clinical-only = 0.646, biomarker-only = 0.740, and combined = 0.744. We displayed the heterogenetic nature of an individual's risk for developing low PMA and identified 2 distinct subtypes of participants who developed low PMA. While additional validation is required, our methods for identifying and understanding individual and group risk for low muscle mass could be used to enable developments in the personalized prevention of low muscle mass.

Skeletal muscle mass and function are affected by pancreatic atrophy, pancreatic exocrine insufficiency and poor nutritional status in patients with chronic pancreatitis

BACKGROUND/OBJECTIVE

Previous studies have demonstrated that sarcopenia is frequently observed in patients with chronic pancreatitis (CP). However, most studies have defined sarcopenia solely based on skeletal muscle (SM) loss, and muscle weakness such as grip strength (GS) reduction has not been considered. We aimed to clarify whether SM loss and reduced GS have different associations with clinical characteristics and pancreatic imaging findings in patients with CP.

METHODS

One hundred two patients with CP were enrolled. We defined SM loss by the SM index at the third lumbar vertebra on CT (<42 cm2/m2 for males and <38 cm2/m2 for females), and reduced GS by < 28 kg for males and <18 kg for females.

RESULTS

Fifty-seven (55.9 %) patients had SM loss, 21 (20.6 %) had reduced GS, and 17 (16.7 %) had both. Patients with SM loss had lower body mass index, weaker GS, higher Controlling Nutritional Status score, lower serum lipase level, and lower urinary para-aminobenzoic acid excretion rate, suggesting worse nutritional status and pancreatic exocrine insufficiency. On CT, main pancreatic duct dilatation and parenchymal atrophy were more frequent in patients with SM loss than in those without it. Patients with reduced GS were older and had worse nutritional status than those without it.

CONCLUSIONS

SM loss was associated with pancreatic exocrine insufficiency, low nutritional status, and pancreatic imaging findings such as parenchymal atrophy and main pancreatic duct dilatation, whereas older age and low nutritional status led to additional reduced GS.

Diabetes Mellitus Should Be Considered While Analysing Sarcopenia-Related Biomarkers

Sarcopenia is a chronic, progressive skeletal muscle disease characterised by low muscle strength and quantity or quality, leading to low physical performance. Patients with type 2 diabetes mellitus (T2DM) are more at risk of sarcopenia than euglycemic individuals. Because of several shared pathways between the two diseases, sarcopenia is also a risk factor for developing T2DM in older patients. Various biomarkers are under investigation as potentially valuable for sarcopenia diagnosis and treatment monitoring. Biomarkers related to sarcopenia can be divided into markers evaluating musculoskeletal status (biomarkers specific to muscle mass, markers of the neuromuscular junction, or myokines) and markers assuming causal factors (adipokines, hormones, and inflammatory markers). This paper reviews the current knowledge about how diabetes and T2DM complications affect potential sarcopenia biomarker concentrations. This review includes markers recently proposed by the expert group of the European Society for the Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) as those that may currently be useful in phase II and III clinical trials of sarcopenia: myostatin (MSTN); follistatin (FST); irisin; brain-derived neurotrophic factor (BDNF); procollagen type III N-terminal peptide (PIIINP; P3NP); sarcopenia index (serum creatinine to serum cystatin C ratio); adiponectin; leptin; insulin-like growth factor-1 (IGF-1); dehydroepiandrosterone sulphate (DHEAS); C-reactive protein (CRP); interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α). A better understanding of factors influencing these biomarkers' levels, including diabetes and diabetic complications, may lead to designing future studies and implementing results in clinical practice.

A leaky gut contributes to reduced sarcopenia-related quality of life (SarQoL) in geriatric older adults

PURPOSE

The sarcopenia quality-of-life (SarQoL) questionnaire is designed to evaluate the quality of life of sarcopenic patients. A pathological increase in intestinal permeability leads to several systemic diseases, but its contribution to SarQoL is unknown.

METHODS

We recruited controls (n = 84, age = 74.6 ± 4.9 years) and sarcopenic (n = 55, age = 76.1 ± 4.2 years) men for validating and adapting a Pashto version of SarQoL. We measured the scores for seven domains of SarQoL, body composition, and handgrip strength (HGS). We also measured plasma zonulin as a marker of increased intestinal permeability.

RESULTS

The Pashto SarQoL exhibited adequate discriminative ability, construct validity, internal consistency, and test-retest reliability, without exhibiting the floor and ceiling effect. Sarcopenic patients had higher plasma zonulin and lower scores on SarQoL domains for physical and mental health, locomotion, body composition, functionality, activities of daily living, leisure, and fear, and cumulative SarQoL scores than controls. Plasma zonulin exhibited significant coefficients of determination with Pashto SarQoL domains for locomotion (r2 = 0.217), functionality (r2 = 0.101), activities of daily living (r2 = 0.302), and cumulative SarQoL scores (r2 = 0.168). We also found high efficacies of zonulin in diagnosing low scores for functionality (AUC = 0.785, 95% C.I = 0.708-0.863), activities of daily living (AUC = 0.785, 95% C.I = 0.708-0.863), and cumulative SarQoL scores (AUC = 0.821, 95% C.I = 0.751-0.891).

CONCLUSION

Altogether, SarQoL appears reliable in measuring the quality of life in sarcopenic patients. A leaky gut has a potential contribution to reduced SarQoL in sarcopenia.

Butyrate supplementation reduces sarcopenia by repairing neuromuscular junction in patients with chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is associated with an intestinal leak and neuromuscular junction (NMJ) degradation, which contributes to physical compromise and accelerated age-related muscle loss, called sarcopenia. However, the relevant interventions partly remain ineffective. We investigated the effects of exogenous butyrate on sarcopenia and physical capacity with relevance to intestinal permeability and NMJ integrity in COPD patients.

METHODS

COPD patients were randomized into placebo (n = 67) and butyrate (n = 64) groups in a double-blind manner. The patients in the butyrate group received one 300 mg capsule a day for 12 weeks. We measured circulating markers of intestinal leak (zonulin), systemic bacterial load (LBP), and NMJ loss (CAF22), along with handgrip strength (HGS), and short physical performance battery (SPPB) at baseline and 12 weeks.

RESULTS

Butyrate supplementation improved HGS and gait speed in COPD patients. Among SPPB indices, butyrate improved the ability to maintain postural balance and walking and prevented a decline in the ability to rise from a chair. Butyrate also reduced the plasma levels of zonulin, LBP, and CAF22 levels in COPD patients (all p < 0.05). Regression analysis revealed significant associations of plasma zonulin and CAF22 with HGS, gait speed, and cumulative SPPB scores in butyrate group. These changes were associated with reduced markers of inflammation and muscle damage.

CONCLUSION

Butyrate may provide a therapeutic approach to sarcopenia and physical dependency in COPD by repairing intestinal leak and NMJ loss.

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.

Higher Baseline Serum Myokine of FSTL1 May Serve as a Potential Predictive Biomarker for Successful Brace Treatment in Girls With Adolescent Idiopathic Scoliosis

STUDY DESIGN

A retrospective case-control study.

OBJECTIVE

This study aimed to investigate whether myokine, which is related to exercise and muscle mass, could serve as a biomarker for predicting bracing outcomes.

SUMMARY OF BACKGROUND DATA

Several risk factors have been documented to be associated with bracing failure in patients with adolescent idiopathic scoliosis (AIS). However, serum biomarkers have not been extensively explored.

PATIENTS AND METHODS

Skeletally immature females with AIS, without previous histories of bracing or surgery, were included. Peripheral blood was collected at the time of the bracing prescription. Baseline serum concentrations of 8 myokines [apelin, fractalkine, brain-derived neurotrophic factor, erythropoietin, osteonectin, fatty-acid-binding protein 3, follistatin-like 1 (FSTL1), and musclin] were measured by multiplex assays. Patients were followed up until weaned from bracing and then designated as a "failure" (defined as Cobb angle progression >5°) or "success." A logistic regression analysis was performed that accounted for serum myokines and skeletal maturity.

RESULTS

We included 117 patients, with 27 in the failure group. Patients in the failure group had lower initial Risser sign and lower baseline serum levels of myokines, including FSTL1 (2217.3 ± 617.0 vs . 1369.3 ± 704.9, P = 0.002), apelin [116.5 (12.0, 335.9) vs . 83.5 (10.5, 221.1), P = 0.016], fractalkine (979.6 ± 457.8 vs . 743.8 ± 456.1, P = 0.020), and musclin [211.3 (16.3, 370.3) vs . 67.8 (15.5, 325.6), P = 0.049]. Following adjusted analysis, serum FSTL1 [odds ratio = 10.460; (2.213-49.453)] was determined to be predictive of bracing effectiveness.

CONCLUSION

Patients who failed AIS bracing had significantly lower mean baseline levels of FSTL1 than those who achieved success. FSTL1 may serve as a biomarker that can inform outcomes after bracing.

Development of multiple biomarker panels for prediction of sarcopenia in community-dwelling older adults

BACKGROUND

It is required to consider multiple biomarkers simultaneously to predict sarcopenia and to understand its complex pathological mechanisms. This study aimed to develop multiple biomarker panels for predicting sarcopenia in older adults and to further examine its association with the incidence of sarcopenia.

METHODS

A total of 1,021 older adults were selected from the Korean Frailty and Aging Cohort Study. Sarcopenia was defined by the Asian Working Group for Sarcopenia 2019 criteria. Among the 14 biomarker candidates at baseline, eight biomarkers that could optimally detect individuals with sarcopenia were selected to develop a multi-biomarker risk score (range from 0 to 10). The utility of developed multi-biomarker risk score in discriminating sarcopenia was investigated using receiver operating characteristic (ROC) analysis.

RESULTS

The multi-biomarker risk score had an area under the ROC curve (AUC) of 0.71 with an optimal cut-off of 1.76 score, which was significantly higher than all single biomarkers with AUC of <0.7 (all, p<0.01). During the two-year follow-up, the incidence of sarcopenia was 11.1%. Continuous multi-biomarker risk score was positively associated with incidence of sarcopenia after adjusting confounders (odds ratio [OR]=1.63; 95% confidence interval [CI]=1.23-2.17). Participants with a high risk score had higher odds of sarcopenia than those with a low risk score (OR=1.82; 95% CI=1.04-3.19).

CONCLUSIONS

Multi-biomarker risk score, which was a combination of eight biomarkers with different pathophysiologies, better discriminated the presence of sarcopenia than a single biomarker, and it could further predict the incidence of sarcopenia over two years in older adults.

Association between F2-Isoprostane Metabolites and Weight Change in Older Women: A Longitudinal Analysis

INTRODUCTION

Theoretically, some metabolic traits may predispose older individuals to weight loss during aging, leading to increased all-cause mortality and many serious health issues. Biomarkers to robustly predict progressive weight loss during aging are, however, lacking. We prospectively assessed if urinary levels of F2-isoprostanes and their peroxisomal β-oxidation metabolite, 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (F2-IsoP-M), were associated with subsequent weight loss in middle-aged and older women.

METHODS

Included in the analysis were 2,066 women aged 40-70 years, a subset of a prospective cohort study. F2-isoprostanes (F2-IsoPs) and its β-oxidation metabolite, F2-IsoP-M, were measured in urine using gas chromatography-mass spectrometry. Measurements of anthropometry and exposures to major determinants of body weight were performed at baseline and repeated thrice over 15-year follow-up. The longitudinal associations of F2-IsoP-M and the F2-IsoP-M to its parent compound, F2-IsoP, ratio (MPR) with repeatedly measured weight changes were examined using linear mixed-effect models.

RESULTS

After adjusting for time-varying covariates: energy intake, physical activity, and comorbidity index, among others, levels of F2-IsoP-M and the MPR were both inversely associated with percentage of weight change. Weight in the highest quartile of these two biomarkers was 1.33% (95% CI = -2.41, -0.24) and 1.09% (95% CI = -2.16, -0.02) lower than those in the lowest quartile group, with p for trend of 0.01 and 0.03, respectively. The inverse association was consistently seen across follow-up periods, although appearing stronger with prolonged follow-up. There was no association between the parent compound, F2-IsoPs, and weight change.

CONCLUSION

This study demonstrates the first piece of evidence to associate F2-IsoP metabolism, peroxisomal β-oxidation, with weight loss in older women. Further investigations into the role of lipid peroxidation and peroxisomal β-oxidation in weight change among older individuals are warranted.

Targeting neuromuscular junction to treat neuromuscular disorders

The integrity and preservation of the neuromuscular junction (NMJ), the interface between the motor neuron and skeletal muscle, is critical for maintaining a healthy skeletal muscle. The structural and/or functional defects in the three cellular components of NMJ, namely the pre-synaptic terminal, synaptic cleft, and post-synaptic region, negatively affect skeletal muscle mass and/or strength. Therefore, NMJ repair appears to be an appropriate therapy for muscle disorders. Mouse models provide a detailed molecular characterization of various cellular components of NMJ with relevance to human diseases. This review discusses different molecular targets on the three cellular components of NMJ for treating muscle diseases. The potential effects of these therapies on NMJ morphology and motor performance, their therapeutic efficacy, and clinical relevance are discussed. Collectively, the available data supports targeting NMJ alone or as an adjunct therapy in treating muscle disorders. However, the potential impact of such interventions on human patients with muscle disorders requires further investigation.

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.

Validated Tools for Screening Sarcopenia: A Scoping Review

OBJECTIVE

Choosing the optimal sarcopenia screening tool for a specific clinical scenario is challenging. We aimed to summarize all validated sarcopenia screening tools with diagnostic accuracy tested in one or more study populations.

DESIGN

Scoping review.

SETTING AND PARTICIPANTS

Hospitals, nursing homes, communities, or health checkups.

METHODS

We systematically searched 3 databases in April 2022: MEDLINE, EMBASE, and CENTRAL. Two review authors independently performed the study selection and data extraction. The included tools' contents, characteristics, and number of citations were summarized and visualized.

RESULTS

We summarized 102 diagnostic accuracy studies involving 53 screening tools, classified into 7 groups: questionnaires (n = 13); serum biomarkers (n = 10); formulas, algorithms, and models (n = 9); physical ability tests (n = 9); integration tools (n = 7); anthropometric indices (n = 3); and ultrasound or bioimpedance analysis (n = 2). The most commonly used questionnaire was SARC-F (770 citations), followed by SARC-CalF (254 citations) and MSRA-7 (61 citations). Handgrip strength and Ishii score were the most widely used physical performance tests (331 citations) and formulas (294 citations), respectively. Sarcopenia index (based on serum cystatin C and creatinine) and calf circumference were the most commonly used serum biomarkers (123 citations) and anthropometric indexes (127 citations), respectively. Ultrasound was the most commonly used imaging tool for screening sarcopenia (57 citations). The included tools varied significantly in content. Various tools assessed some or all components of sarcopenia with different methods, and others assessed different domains, such as age, body mass index, falls, diet, and even mental health. We also summarized the screening tools that were validated in different clinical settings (hospitals, communities, nursing homes, and health checkups).

CONCLUSIONS AND IMPLICATIONS

More than 50 validated tools are currently available for screening sarcopenia in different clinical settings. The results of this review may help clinicians and researchers in selecting optimal tools for sarcopenia in different clinical scenarios and in developing future tools.

Irisin Ameliorated Skeletal Muscle Atrophy by Inhibiting Fatty Acid Oxidation and Pyroptosis Induced by Palmitic Acid in Chronic Kidney Disease

INTRODUCTION

Protein-energy waste (PEW) is a common complication in patients with chronic kidney disease (CKD), among which skeletal muscle atrophy is one of the most important clinical features of PEW. Pyroptosis is a type of proinflammatory, programmed cell death associated with skeletal muscle disease. Irisin, as a novel myokine, has attracted extensive attention for its protective role in the complications associated with CKD, but its role in muscle atrophy in CKD is unclear.

METHODS

Palmitic acid (PA)-induced muscular atrophy was evaluated by a reduction in C2C12 myotube diameter. Muscle atrophy model was established in male C57BL/6J mice treated with 0.2% adenine for 4 weeks and then fed a 45% high-fat diet. Blood urea nitrogen and creatinine levels, body and muscle weight, and muscle histology were assessed. The expression of carnitine palmitoyltransferase 1A (CPT1A) and pyroptosis-related protein was analysed by Western blots or immunohistochemistry. The release of IL-1β was detected by enzyme-linked immunosorbent assay.

RESULTS

In this study, we showed that PA-induced muscular atrophy manifested as a reduction in C2C12 myotube diameter. During this process, PA can also induce pyroptosis, as shown by the upregulation of NLRP3, cleaved caspase-1 and GSDMD-N expression and the increased IL-1β release and PI-positive cell rate. Inhibition of caspase-1 or NLRP3 attenuated PA-induced pyroptosis and myotube atrophy in C2C12 cells. Importantly, irisin treatment significantly ameliorated PA-induced skeletal muscle pyroptosis and atrophy. In terms of mechanism, PA upregulated CPT1A, a key enzyme of fatty acid oxidation (FAO), and irisin attenuated this effect, which was consistent with etomoxir (CPT1A inhibitor) treatment. Moreover, irisin improved skeletal muscle atrophy and pyroptosis in adenine-induced mice by regulating FAO.

CONCLUSION

Our study firstly verifies that pyroptosis is a novel mechanism of skeletal muscle atrophy in CKD. Irisin ameliorates skeletal muscle atrophy by inhibiting FAO and pyroptosis in CKD, and irisin may be developed as a potential therapeutic agent for the treatment of muscle wasting in CKD patients.

Circulating H-FABP as a biomarker of frailty in patients with chronic heart failure

Increased vulnerability to physiologic stressors, termed frailty, is a common occurrence in patients with chronic heart failure (CHF). However, the definite biomarkers to assess frailty in CHF patients are not known. Here, we assessed the frailty phenotype and its potential association with heart failure (HF) markers in CHF patients. We categorized controls (n = 59) and CHF patients (n = 80), the participants, into robust, pre-frail, and frail based on the cardiovascular health study (CHS) frailty index. The plasma levels of HF markers, including tumorigenicity 2 (s-ST2), galectin-3, and heart-type fatty acid binding protein (H-FABP), were measured and correlated with frailty phenotype and cardiac function. The levels of plasma s-ST2, galectin-3, and H-FABP were profoundly elevated in CHF patients. Conversely, the frailty index scores were significantly lower in ischemic and non-ischemic CHF patients versus controls. Of the assessed HF markers, only H-FABP was positively correlated (r2 = 0.07, P = 0.02) with the frailty score in CHF patients. Collectively, these observations suggest that circulating H-FABP may serve as a biomarker of frailty in CHF patients.

Comparison of Protein- or Amino Acid-Based Supplements in the Rehabilitation of Men with Severe Obesity: A Randomized Controlled Pilot Study

BACKGROUND

Weight loss is associated with a reduction in all body compartments, including muscle mass (MM), and this effect produces a decrease in function and muscle strength. Our objective was to assess the impact of protein or amino acid supplements on MM loss in middle-aged men (age < 65 years) with severe obesity (BMI > 35 kg/m2) during weight loss.

MATERIALS AND METHODS

We conducted a single-site randomized controlled trial (Clinicaltrials.gov NCT05143398) with 40 in-patient male subjects with severe obesity. Participants underwent an intervention program consisting of a low-calorie balanced diet and structured physical activity. They were randomly assigned to 4-week treatment groups: (1) control (CTR, N = 10), (2) protein (P, N = 10), (3) branched-chain amino acid (BCAA, N = 10), and (4) essential amino acid mixture with tricarboxylic acid cycle intermediates (PD-E07, N = 10) supplementation.

RESULTS

Following 4 weeks of intervention, all groups showed similar reductions in body weight compared to baseline. When examining the delta values, a notable increase in muscle mass (MM) was observed in the PD-E07 intervention group [MM (kg): 2.84 ± 3.57; MM (%): 3.63 ± 3.14], in contrast to the CTR group [MM (kg): -2.46 ± 3.04; MM (%): -0.47 ± 2.28], with a statistical significance of p = 0.045 and p = 0.023, respectively. However, the MM values for the P group [MM (kg): -2.75 ± 5.98, p = 0.734; MM (%): -0.44 ± 4.02, p = 0.990] and the BCAA group [MM (kg): -1 ± 3.3, p = 0.734; MM (%): 0.34 ± 2.85, p = 0.956] did not exhibit a statistically significant difference when compared to the CTR group.

CONCLUSIONS

Amino acid-based supplements may effectively mitigate the loss of MM typically observed during weight reduction. Further validation through large-scale studies is necessary.

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.

Degradation of neuromuscular junction contributes to muscle weakness but not physical compromise in chronic obstructive pulmonary disease patients taking lipids-lowering medications

OBJECTIVES

The relevant data about the effects and the associated mechanisms of statins on muscle strength and physical capacity is inconsistent. We investigated the potential contribution of neuromuscular junction (NMJ) degradation to muscle weakness and physical compromise in patients with chronic obstructive pulmonary disease (COPD) on statins.

METHOD

We recruited male COPD patients (age range = 63-75 years, n = 150) as nonusers (n = 71) and users of statin medications (n = 79) along with age-matched controls (n = 76). The COPD patients were evaluated at baseline and one year later. The data about handgrip strength (HGS), body composition, short physical performance battery (SPPB), and plasma c-terminal agrin fragment-22 (CAF22) as a marker of NMJ disintegration was collected at two time points.

RESULTS

We observed lower HGS, SPPB scores, and higher CAF22 levels in all COPD patients than controls, irrespective of the treatment status (all p < 0.05). Statins further reduced HGS and elevated CAF22 in COPD patients (both p < 0.05). The decline in SPPB was relatively modest in statin users (≈3.7%, p = 0.032) than in nonusers (≈8.7%, p = 0.002). The elevated plasma CAF22 exhibited robust negative correlations with a reduction in HGS but not with SPPB in COPD patients taking statins. We also found a reduction in markers of inflammation and no increase in oxidative stress markers following statin use in COPD patients.

CONCLUSION

Altogether, statin-induced NMJ degradation exacerbates muscle decline but does not contribute to physical compromise in COPD patients.

Changes in selected exerkines concentration post folk-dance training are accompanied by glucose homeostasis and physical performance improvement in older adults

The study aimed to evaluate the impact of selected exerkines concentration induced by folk-dance and balance training on physical performance, insulin resistance, and blood pressure in older adults. Participants (n = 41, age 71.3 ± 5.5 years) were randomly assigned to folk-dance (DG), balance training (BG), or control group (CG). The training was performed 3 times a week for 12 weeks. Physical performance tests-time up and go (TUG) and 6-min walk test (6MWT), blood pressure, insulin resistance, and selected proteins induced by exercise (exerkines) were assessed at baseline and post-exercise intervention. Significant improvement in TUG (p = 0.006 for BG and 0.039 for DG) and 6MWT tests (in BG and DG p = 0.001), reduction of systolic blood pressure (p = 0.001 for BG and 0.003 for DG), and diastolic blood pressure (for BG; p = 0.001) were registered post-intervention. These positive changes were accompanied by the drop in brain-derived neurotrophic factor (p = 0.002 for BG and 0.002 for DG), the increase of irisin concentration (p = 0.029 for BG and 0.022 for DG) in both groups, and DG the amelioration of insulin resistance indicators (HOMA-IR p = 0.023 and QUICKI p = 0.035). Folk-dance training significantly reduced the c-terminal agrin fragment (CAF; p = 0.024). Obtained data indicated that both training programs effectively improved physical performance and blood pressure, accompanied by changes in selected exerkines. Still, folk-dance had enhanced insulin sensitivity.

Imaging Techniques to Determine Degree of Sarcopenia and Systemic Inflammation in Advanced Renal Cell Carcinoma

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date understanding regarding the literature on sarcopenia and inflammation as prognostic factors in the context of renal cell carcinoma (RCC).

RECENT FINDINGS

Sarcopenia is increasingly recognized as a prognostic factor in RCC. Emerging literature suggests monitoring quantity of muscle on successive imaging and examining muscle density may be additionally informative. Inflammation has prognostic ability in RCC and is also considered a key contributor to development and progression of both RCC and sarcopenia. Recent studies suggest these two prognostic factors together may provide additional prognostic ability when used in combination. Ongoing developments include quality control regarding sarcopenia research and imaging, improving understanding of muscle loss mechanisms, and enhancing clinical incorporation of sarcopenia via improving imaging analysis practicality (i.e., artificial intelligence) and feasible biomarkers. Sarcopenia and systemic inflammation are complementary prognostic factors for adverse outcomes in patients with RCC. Further study on high-quality sarcopenia assessment standardization and expedited sarcopenia assessment is desired for eventual routine clinical incorporation of these prognostic factors.

Plasma Galectin-3 and H-FABP correlate with poor physical performance in patients with congestive heart failure

Heart failure (HF) is often associated with compromised physical capacity in patients. However, it is unclear if established HF markers correlate with the physical performance of patients with congestive HF (CHF). We assessed the left ventricular end-systolic dimension (LVESD) and ejection fraction (LVEF) and, physical performance parameters, including short physical performance battery (SPPB), gait speed (GS), and handgrip strength (HGS) in 80 patients with CHF along with 59 healthy controls. Furthermore, levels of plasma HF markers galectin-3 and heart-specific fatty acid binding protein (H-FABP) were measured in relation to the severity of HF and physical performance. Irrespective of etiology, significantly greater LVESD and lower LVEF were observed in HF patients versus controls. As expected, the levels of HF markers galectin-3 and H-FABP were upregulated in the CHF patients which were accompanied by significantly elevated levels of plasma zonulin and inflammatory marker C-reactive protein (CRP). The SPPB scores, GS, and HGS were significantly lower in the ischemic and non-ischemic HF patients than controls. The level of galectin-3 was inversely correlated with SPPB scores (r2 = 0.089, P = 0.01) and HGS (r2 = 0.078, P = 0.01). Similarly, H-FABP levels were also inversely correlated with SPPB scores (r2 = 0.06, P = 0.03) and HGS (r2 = 0.109, P = 0.004) in the patients with CHF. Taken together, CHF adversely affects physical performance, and galectin-3 and H-FABP may serve as biomarkers of physical disability in patients with CHF. The robust correlations of galectin-3 and H-FABP with the physical performance parameters and CRP in CHF patients suggest that the poor physical performance may partly be caused due to systemic inflammation.

C-terminal agrin fragment as a biomarker of muscle wasting and weakness: a narrative review

Ageing is accompanied by an inexorable loss of muscle mass and functionality and represents a major risk factor for numerous diseases such as cancer, diabetes and cardiovascular and pulmonary diseases. This progressive loss of muscle mass and function may also result in the insurgence of a clinical syndrome termed sarcopenia, exacerbated by inactivity and disease. Sarcopenia and muscle weakness yield the risk of falls and injuries, heavily impacting on health and social costs. Thus, screening, monitoring and prevention of conditions inducing muscle wasting and weakness are essential to improve life quality in the ageing modern society. To this aim, the reliability of easily accessible and non-invasive blood-derived biomarkers is being evaluated. C-terminal agrin fragment (CAF) has been widely investigated as a neuromuscular junction (NMJ)-related biomarker of muscle dysfunction. This narrative review summarizes and critically discusses, for the first time, the studies measuring CAF concentration in young and older, healthy and diseased individuals, cross-sectionally and in response to inactivity and physical exercise, providing possible explanations behind the discrepancies observed in the literature. To identify the studies investigating CAF in the above-mentioned conditions, all the publications found in PubMed, written in English and measuring this biomarker in blood from 2013 (when CAF was firstly measured in human serum) to 2022 were included in this review. CAF increases with age and in sarcopenic individuals when compared with age-matched, non-sarcopenic peers. In addition, CAF was found to be higher than controls in other muscle wasting conditions, such as diabetes, COPD, chronic heart failure and stroke, and in pancreatic and colorectal cancer cachectic patients. As agrin is also expressed in kidney glomeruli, chronic kidney disease and transplantation were shown to have a profound impact on CAF independently from muscle wasting. CAF concentration raises following inactivity and seems to be lowered or maintained by exercise training. Finally, CAF was reported to be cross-sectionally correlated to appendicular lean mass, handgrip and gait speed; whether longitudinal changes in CAF are associated with those in muscle mass or performance following physical exercise is still controversial. CAF seems a reliable marker to assess muscle wasting in ageing and disease, also correlating with measurements of appendicular lean mass and muscle function. Future research should aim at enlarging sample size and accurately reporting the medical history of each patient, to normalize for any condition, including chronic kidney disease, that may influence the circulating concentration of this biomarker.

Biochemical Markers of Musculoskeletal Health and Aging to be Assessed in Clinical Trials of Drugs Aiming at the Treatment of Sarcopenia: Consensus Paper from an Expert Group Meeting Organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) and the Centre Académique de Recherche et d'Expérimentation en Santé (CARES SPRL), Under the Auspices of the World Health Organization Collaborating Center for the Epidemiology of Musculoskeletal Conditions and Aging

In clinical trials, biochemical markers provide useful information on the drug's mode of action, therapeutic response and side effect monitoring and can act as surrogate endpoints. In pharmacological intervention development for sarcopenia management, there is an urgent need to identify biomarkers to measure in clinical trials and that could be used in the future in clinical practice. The objective of the current consensus paper is to provide a clear list of biochemical markers of musculoskeletal health and aging that can be recommended to be measured in Phase II and Phase III clinical trials evaluating new chemical entities for sarcopenia treatment. A working group of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) proposed classifying biochemical markers into 2 series: biochemical markers evaluating musculoskeletal status and biochemical markers evaluating causal factors. For series 1, the group agreed on 4 biochemical markers that should be assessed in Phase II or Phase III trials (i.e., Myostatin-Follistatin, Brain Derived Neurotrophic Factor, N-terminal Type III Procollagen and Serum Creatinine to Serum Cystatin C Ratio - or the Sarcopenia Index). For series 2, the group agreed on 6 biochemical markers that should be assessed in Phase II trials (i.e., the hormones insulin-like growth factor-1 (IGF-I), dehydroepiandrosterone sulphate, and cortisol, and the inflammatory markers C-reactive protein (CRP), interleukin-6 and tumor necrosis factor-α), and 2 in Phase III trials (i.e., IGF-I and CRP). The group also proposed optional biochemical markers that may provide insights into the mode of action of pharmacological therapies. Further research and development of new methods for biochemical marker assays may lead to the evolution of these recommendations.

Reduced upper and lower limb muscle strengths without reduced skeletal muscle in elderly patients with heart failure

Objective: This study aimed to characterize the muscle strength and skeletal muscle mass of patients with heart failure by investigating hand-grip strength, five times sit-to-stand (5STS) results, and skeletal muscle mass index (SMI). Materials and Methods: Muscle strength was assessed based on hand-grip strength and 5STS, while skeletal muscle mass was assessed using a bioelectrical impedance analyzer. Hierarchical logistic regression analysis was performed to explore the association between patients with heart failure and healthy elderly individuals. Results: Hierarchical logistic regression analysis was performed to examine the muscle strength and skeletal muscle mass characteristics in patients with heart failure. Hand-grip strength and 5STS responses but not SMI outcomes differed significantly between the two groups. The results of the hierarchical logistic regression analysis revealed that the hand-grip strength and 5STS were significant predictors of heart failure. The odds ratios for hand-grip strength and 5STS were 1.44 and 0.53, respectively. Conclusion: Our results suggested that upper and lower limb muscle strengths (handgrip strength and 5STS) in elderly patients with heart failure worsened significantly without a decrease in skeletal muscle mass.

Serum transthyretin and aminotransferases are associated with lean mass in people with coronary heart disease: Further insights from the CARE-CR study

Background

Low muscle mass disproportionately affects people with coronary heart disease compared to healthy controls but is under-researched and insufficiently treated. Inflammation, poor nutrition, and neural decline might contribute to low muscle mass. This study aimed to assess circulatory biomarkers related to these mechanisms [albumin, transthyretin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and C-terminal agrin fragment] and their relationship with muscle mass in people with coronary heart disease. Our findings could be beneficial to indicate mechanisms of sarcopenia, detect sarcopenia, and evaluate treatment.

Methods

Serum blood samples from people with coronary heart disease were analysed for biomarker concentrations using enzyme-linked immunosorbent assays. Skeletal muscle mass was estimated using dual X-ray absorptiometry derived appendicular lean mass and reported as skeletal muscle index (SMI; kg m^-2), and as a proportion of total body mass [appendicular skeletal mass (ASM%)]. Low muscle mass was defined as a SMI <7.0 and <6.0 kg m^-2, or ASM% <25.72 and <19.43% for men and women, respectively. Associations between biomarkers and lean mass were adjusted for age and inflammation.

Results

Sixty-four people were assessed; 14 (21.9%) had low muscle mass. People with low muscle mass had lower transthyretin (effect size 0.34, p = 0.007), ALT (effect size 0.34, p = 0.008), and AST (effect size 0.26, p = 0.037) concentrations, compared to those with normal muscle mass. SMI was associated with inflammation-corrected ALT (r = 0.261, p = 0.039) and with inflammation- and age-adjusted AST/ALT ratio (r = -0.257, p = 0.044). Albumin and C-terminal agrin fragment were not associated with muscle mass indices.

Conclusion

Circulatory transthyretin, ALT and AST were associated with low muscle mass in people with coronary heart disease. Low concentrations of these biomarkers might indicate that low muscle mass is partially explained by poor nutrition and high inflammation in this cohort. Targeted treatments to address these factors could be considered for people with coronary heart disease.

Transitional Dynamics of Sarcopenia and Associations of Nutritional Indices with State Transitions in Chinese aged ≥ 50

OBJECTIVES

Sarcopenia's temporal profile can be regarded as a dynamic process with distinct states, in which malnutrition plays an important role. This study aimed to address two research gaps: sarcopenia's transitional dynamics and associations of nutritional indices with state transitions in community-dwelling Chinese adults aged 50 and older.

DESIGN

A prospective population-based cohort study.

SETTING

Community-based setting in western China.

PARTICIPANTS

The analytic sample included data from 1910 participants aged ≥ 50 in the West China Health and Aging Trend study between 2018-2022.

MEASUREMENTS

We defined three states: the initial normal state (normal muscle strength, physical performance and muscle mass), the worst sarcopenia state (low muscle mass plus low muscle strength and/or low physical performance) and the intermediate subclinical state (the other scenarios). The relevant measurement methods and cut-off points were based on the 2019 AWGS consensus. Using a continuous-time multistate Markov model, we calculated probabilities of transitions between different states over 1, 2 and 4 years; we also examined associations between nutritional indices and transitions, including body mass index (BMI), calf circumference (CC), mid-arm circumference (MAC), triceps skinfold thickness (TST), albumin (ALB), geriatric nutrition risk index (GNRI), vitamin D (VitD) and prealbumin (PA).

RESULTS

For individuals in the normal state, their probabilities of remaining stable versus progressing to a subclinical state were 53.4% versus 42.1% at 2 years, and 40.6% versus 49.0% at 4 years. In the subclinical population, their 2- and 4-year chances were 60.2% and 51.2% for maintaining this state, 11.8% and 16.2% for developing sarcopenia, 28.0% and 32.6% for reverting to normal. For sarcopenic individuals, the likelihood of staying stable versus retrogressing to the subclinical state were 67.0% versus 26.3% at 2 years, and 48.3% versus 36.3% at 4 years. Increased BMI, CC, MAC, TST, ALB, GNRI and PA correlated with reversion from the subclinical state, among which increased TST, ALB and PA were also paralleled with reversion from sarcopenia, while decreased BMI, CC, MAC, TST and GNRI were associated with progression to sarcopenia. VitD was not significantly associated with any transitions.

CONCLUSION

This study reveals how sarcopenia changes over time in a Chinese population. It also highlights the usefulness of simple and cost-effective nutritional status indices for indicating state transitions, which can help identify individuals at risk of sarcopenia and guide targeted interventions within the optimal time window.

Revisiting skeletal myopathy and exercise training in heart failure: Emerging role of myokines

Exercise intolerance remains a major unmet medical need in patients with heart failure (HF). Skeletal myopathy is currently considered as the major limiting factor for exercise capacity in HF patients. On the other hand, emerging evidence suggest that physical exercise can decrease morbidity and mortality in HF patients. Therefore, mechanistic insights into skeletal myopathy may uncover critical aspects for therapeutic interventions to improve exercise performance in HF. Emerging data reviewed in this article suggest that the assessment of circulating myokines (molecules synthesized and secreted by skeletal muscle in response to contraction that display autocrine, paracrine and endocrine actions) may provide new insights into the pathophysiology, phenotyping and prognostic stratification of HF-related skeletal myopathy. Further studies are required to determine whether myokines may also serve as biomarkers to personalize the modality and dose of physical training prescribed for patients with HF and exercise intolerance. In addition, the production and secretion of myokines in patients with HF may interact with systemic alterations (e.g., inflammation and metabolic disturbances), frequently present in patients with HF. Furthermore, myokines may exert beneficial or detrimental effects on cardiac structure and function, which may influence adverse cardiac remodelling and clinical outcomes in HF patients. Collectively, these data suggest that a deeper knowledge on myokines regulation and actions may lead to the identification of novel physical exercise-based therapeutic approaches for HF patients.

Elevated plasma CAF22 are incompletely restored six months after COVID-19 infection in older men

INTRODUCTION

The long-term complications of COVID-19 appear as significant health problems. However, the long-term muscle decline in these patients is poorly characterized.

METHODS

We investigated the age-related muscle decline, termed sarcopenia, before and following the COVID-19 infection in older male patients (n = 87). We evaluated handgrip strength (HGS) and functional capacity (short physical performance battery; SPPB) in COVID-19 patients 7-42 days before and one week and 6-month after COVID-19 infection. We used ELISA tests to measure plasma c-terminal agrin fragment-22 (CAF22), c-reactive protein (CRP), and 8-isoprostanes as markers of degraded neuromuscular junctions, inflammation, and oxidative stress, respectively.

RESULTS

Before the COVID-19 infection, 54 patients were non-sarcopenic, and 25 patients were sarcopenic, while eight patients subsequently developed sarcopenia. All patients exhibited reduced HGS and SPPB, while elevated CAF22, CRP, and 8-isoprostane levels one week post-COVID-19 infection (all p < 0.05). At six months post-COVID-19 infection, the HGS, SPPB, CAF22, CRP, and 8-isoprostanes were partly restored to baseline levels (all p < 0.05). Correlation analysis revealed that the plasma CAF22 had a significant correlation with HGS, SPPB, and COVID-19 disease severity. CAF22 also demonstrated significant areas under the curves in diagnosing sarcopenia at all three time-points.

CONCLUSION

Altogether, the muscle detriment due to COVID-19 persists six months post-infection, and plasma CAF22 may be helpful to detect muscle and functional decline in these patients. Timely evaluation and intervention of sarcopenia may be critical in COVID-19 treatment.

Biomarkers associated with lower limb muscle function in individuals with sarcopenia: a systematic review

Lower limb muscle dysfunction is a key driver for impaired physical capacity and frailty status, both characteristics of sarcopenia. Sarcopenia is the key pathway between frailty and disability. Identifying biological markers for early diagnosis, treatment, and prevention may be key to early intervention and prevention of disability particularly mobility issues. To identify biological markers associated with lower limb muscle (dys)function in adults with sarcopenia, a systematic literature search was conducted in AMED, CINAHL, Cochrane Library, EMBASE, Medline, PubMed, Scopus, SPORTDiscus, and Web of Science databases from inception to 17 November 2021. Title, abstract, and full-text screening, data extraction, and methodological quality assessment were performed by two reviewers independently and verified by a third reviewer. Depending on available data, associations are reported as either Pearson's correlations, regression R² or partial R² , P value, and sample size (n). Twenty eligible studies including 3306 participants were included (females: 79%, males: 15%, unreported: 6%; mean age ranged from 53 to 92 years) with 36% in a distinct sarcopenic subgroup (females: 73%, males: 19%, unreported: 8%; mean age range 55-92 years). A total of 119 biomarkers were reported, categorized into: genetic and microRNAs (n = 64), oxidative stress (n = 10), energy metabolism (n = 18), inflammation (n = 7), enzyme (n = 4), hormone (n = 7), bone (n = 3), vitamin (n = 2), and cytokine (n = 4) markers) and seven lower limb muscle measures predominately focused on strength. Seven studies reported associations between lower limb muscle measures including (e.g. power, force, and torque) and biomarkers. In individuals with sarcopenia, muscle strength was positively associated with free testosterone (r = 0.40, P = 0.01; n = 46). In analysis with combined sarcopenic and non-sarcopenic individuals, muscle strength was positively associated with combined genetic and methylation score (partial R²  = 0.122, P = 0.03; n = 48) and negatively associated with sarcopenia-driven methylation score (partial R²  = 0.401, P < 0.01; n = 48). Biomarkers related to genetics (R²  = 0.001-0.014, partial R²  = 0.013-0.122, P > 0.05; n = 48), oxidative stress (r = 0.061, P > 0.05; n ≥ 77), hormone (r = 0.01, ρ = 0.052 p > 0.05, n ≥ 46) and combined protein, oxidative stress, muscle performance, and hormones (R²  = 22.0, P > 0.05; n ≥ 82) did not report significant associations with lower limb muscle strength. Several biomarkers demonstrated associations with lower limb muscle dysfunction. The current literature remains difficult to draw clear conclusions on the relationship between biomarkers and lower limb muscle dysfunction in adults with sarcopenia. Heterogeneity of biomarkers and lower limb muscle function precluded direct comparison. Use of international classification of sarcopenia and a set of core standardized outcome measures should be adopted to aid future investigation and recommendations to be made.

The Cytokine Growth Differentiation Factor-15 and Skeletal Muscle Health: Portrait of an Emerging Widely Applicable Disease Biomarker

Growth differentiation factor 15 (GDF-15) is a stress-induced transforming growth factor-β superfamily cytokine with versatile functions in human health. Elevated GDF-15 blood levels associate with multiple pathological conditions, and are currently extensively explored for diagnosis, and as a means to monitor disease progression and evaluate therapeutic responses. This review analyzes GDF-15 in human conditions specifically focusing on its association with muscle manifestations of sarcopenia, mitochondrial myopathy, and autoimmune and viral myositis. The use of GDF-15 as a widely applicable health biomarker to monitor muscle disease is discussed, and its potential as a therapeutic target is explored.

Sarcopenia and Frailty in Heart Failure: Is There a Biomarker Signature?

PURPOSE OF REVIEW

Sarcopenia and frailty are common in patients with heart failure (HF) and are strongly associated with prognosis. This review aims to examine promising biomarkers that can guide physicians in identifying sarcopenia and frailty in HF.

RECENT FINDINGS

Traditional biomarkers including C-reactive protein, aminotransaminase, myostatin, and urinary creatinine as well as novel biomarkers including microRNAs, suppression of tumorigenicity 2 (ST2), galectin-3, and procollagen type III N-terminal peptide may help in predicting the development of sarcopenia and frailty in HF patients. Among those biomarkers, aminotransferase, urinary creatinine, and ST2 predicted the prognosis in HF patients with sarcopenia and frailty. This review outlines the current knowledge of biomarkers that are considered promising for diagnosing sarcopenia and frailty in HF. The listed biomarkers might support the diagnosis, prognosis, and therapeutic decisions for sarcopenia and frailty in HF patients.

The Therapeutic Potential of the Endocannabinoid System in Age-Related Diseases

The endocannabinoid system (ECS) dynamically regulates many aspects of mammalian physiology. ECS has gained substantial interest since growing evidence suggests that it also plays a major role in several pathophysiological conditions due to its ability to modulate various underlying mechanisms. Furthermore, cannabinoids, as components of the cannabinoid system (CS), have proven beneficial effects such as anti-inflammatory, immunomodulatory, neuromodulatory, antioxidative, and cardioprotective effects. In this comprehensive review, we aimed to describe the complex interaction between CS and most common age-related diseases such as neuro-degenerative, oncological, skeletal, and cardiovascular disorders, together with the potential of various cannabinoids to ameliorate the progression of these disorders. Since chronic inflammation is postulated as the pillar of all the above-mentioned medical conditions, we also discuss in this paper the potential of CS to ameliorate aging-associated immune system dysregulation.

A multistrain probiotic improves handgrip strength and functional capacity in patients with COPD: A randomized controlled trial

PURPOSE

The age-related muscle loss, termed sarcopenia and functional dependency, are common findings in patients with chronic obstructive pulmonary disease (COPD). However, an effective bedside treatment remains elusive.

OBJECTIVE

To assess the effects of probiotics on sarcopenia and physical capacity in COPD patients.

METHODS

Randomized, double-blind, computer-controlled, multicenter trial in two tertiary-care hospitals for 16 weeks. A central computer system randomly allocated male, 63-73 years old COPD patients into placebo (n=53) and probiotic (n=51) groups. The intervention was Vivomix 112 billion*, one capsule a day for 16 weeks. The main outcomes measured were sarcopenia phenotype, short physical performance battery (SPPB), plasma markers of intestinal permeability (zonulin and claudin-3) and neuromuscular junction degradation (CAF22), body composition, and handgrip strength (HGS) before and following the probiotics treatment.

FINDINGS

4 patients discontinued intervention due to poor compliance and 100 patients, including placebo (n=53) and probiotic (n=47) groups were analyzed. Probiotics reduced plasma zonulin, claudin-3, and CAF22, along with an improvement in HGS, gait speed, and SPPB scores (all p<0.05). Probiotic treatment also reduced the plasma c-reactive proteins and 8-isoprostane levels, the markers of systemic inflammation and oxidative stress (p<0.05). Correlation analysis revealed varying degrees of association of plasma biomarkers with sarcopenia indexes. Despite a statistical trend, we did not find a reduction in sarcopenia prevalence in the probiotic group.

CONCLUSION

Taken together, the multistrain probiotic improves muscle strength and functional performance in COPD patients by reducing intestinal permeability and stabilizing neuromuscular junction.

TRIAL REGISTRATION

GMC clinical trial unit, GMC-CREC-00263.

Suppression of endoplasmic reticulum stress prevents disuse muscle atrophy in a mouse model of microgravity

BACKGROUND

Hind-limb unloaded (HLU) mouse model exhibits skeletal muscle atrophy and weakness mimicking the conditions such as prolonged spaceflight. However, the molecular mechanisms and interventions of muscle loss during muscle unloading remain elusive. Dysfunction of protein folding by ednoplasmic reticulum (ER), a condition called ER stress, is implicated in diseases of various cell types, but its contribution to skeletal muscle detriment remains elusive. In this study, we investigated the contribution of ER stress to muscle atrophy.

METHODS

Sixteen-week-old c57BL/6j male mice were grouped into ground-based controls and HLU group, which was subsequently injected with injected saline (HLU-sal.) or pan-ER stress inhibitor 4-PBA (100mg/kg/d; HLU- 4PBA) via intraperitoneal injections for three weeks.

RESULTS

Three weeks of HLU resulted in reduction in muscle mass and strength, which were restored with 4PBA injections. We also report myofibers atrophy, myonuclear apoptosis, and aterations in the expressions of genes associated with ER stress, apoptosis, and calcium dysregulation. These findings were reversed by 4-PBA treatment.

CONCLUSION

Altogether, our results indicate that ER stress contributes to muscle atrophy in HLU conditions. We suggest that blocking ER stress may be an effective pharmacological therapy to prevent muscle weakness and atrophy during prolonged muscle unloading.

Resistin as a Systemic Inflammation-Related Biomarker for Sarcopenia in Patients With Chronic Obstructive Pulmonary Disease

Background

Sarcopenia is common in patients with chronic obstructive pulmonary disease (COPD) and is mainly caused by systemic inflammation. Resistin acts as a proinflammatory cytokine and is involved in the activation of multiple inflammatory signaling pathways. The aim of this study was to determine the relationship between resistin levels and systemic inflammation and to assess the clinical value of circulating resistin for sarcopenia in patients with COPD.

Methods

In this prospective observational study, we enrolled 235 patients with COPD who were divided into development and validation sets. The definition of sarcopenia followed the guidelines from the Asian Working Group for Sarcopenia. Serum concentrations of resistin and TNF-α were measured using an enzyme-linked immunosorbent assay (ELISA).

Results

In this study, higher serum resistin levels were significantly associated with lower skeletal muscle mass and muscular strength. The serum resistin levels in patients with sarcopenia were significantly higher than those in patients without sarcopenia. The serum resistin level had positive correlations with the serum TNF-α level (r = 0.250, p = 0.007). The predictive efficacy of the serum resistin level (AUC: 0.828) for sarcopenia was superior to that of the serum TNF-α level (AUC: 0.621). The cutoff point (7.138 ng/ml) for the serum resistin level was validated in the validation set (AUC: 0.818).

Conclusions

Serum resistin levels were associated with systemic inflammation and can be used accurately and easily to predict sarcopenia in patients with COPD.

Mitigating sarcoplasmic reticulum stress limits disuse-induced muscle loss in hindlimb unloaded mice

Muscle disuse in the hindlimb unloaded (HU) mice causes significant atrophy and weakness. However, the cellular and molecular mechanisms driving disuse-muscle atrophy remain elusive. We investigated the potential contribution of proteins dysregulation by sarcoplasmic reticulum (SR), a condition called SR stress, to muscle loss during HU. Male, c57BL/6j mice were assigned to ground-based controls or HU groups treated with vehicle or 4-phenylbutyrate (4-PBA), a potent inhibitor of SR stress, once a day for three weeks. We report that the 4-PBA reduced the SR stress and partly reversed the muscle atrophy and weakness in the HU mice. Transcriptome analysis revealed that several genes were switched on (n = 3688) or differentially expressed (n = 1184) due to HU. GO, and KEGG term analysis revealed alterations in pathways associated with the assembly of cilia and microtubules, extracellular matrix proteins regulation, calcium homeostasis, and immune modulation during HU. The muscle restoration with 4-PBA partly reversed these changes along with differential and unique expression of several genes. The analysis of genes among the two comparisons (HU-v vs. control and HU-t vs. HU-v.) shows 841 genes were overlapped between the two comparisons and they may be regulated by 4-PBA. Altogether, our findings suggest that the pharmacological suppression of SR stress may be an effective strategy to prevent disuse-induced muscle weakness and atrophy.