Loss of muscle mass and strength with aging, termed sarcopenia is accelerated in several comorbidities including chronic heart failure (CHF) and chronic obstructive pulmonary diseases (COPD). However, the effective circulating biomarkers to accurately diagnose and assess sarcopenia are not known. We recruited male healthy controls and patients with CHF and COPD (n = 81–87/group), aged 55–74 years. Sarcopenia was clinically identified based on hand-grip strength, appendicular skeletal muscle index and physical capacity as recommended by the European working group for sarcopenia. The serum levels of amino-terminal pro-peptide of type-III procollagen, c-terminal agrin fragment-22, osteonectin, irisin, fatty acid-binding protein-3 and macrophage migration inhibitory factor were significantly different between healthy controls and patients with CHF and COPD. Risk scores for individual biomarkers were calculated by logistic regressions and combined into a cumulative risk score. The median cutoff value of 3.86 was used to divide subjects into high- and low-risk groups for sarcopenia with the area under the curve of 0.793 (95% CI = 0.738–0.845, p < 0.001). A significantly higher incidence of clinical sarcopenia was found in high-risk group. Taken together, the battery of biomarkers can be an effective tool in the early diagnosis and assessment of sarcopenia.

Skeletal muscle dysfunction is a critical finding in many respiratory diseases. However, a definitive biomarker to assess muscle decline in respiratory diseases is not known. We analyzed the association of plasma levels of glycoprotein Dickkopf-3 (Dkk-3), c-terminal agrin fragment-22 (CAF22) and microRNAs miR-21, miR-134a, miR-133 and miR-206 with hand-grip strength (HGS) and appendicular skeletal mass index (ASMI) in male, 54–73-year-old patients with chronic obstructive pulmonary diseases (COPD), asthma or pulmonary TB (n = 83–101/group). Patients with respiratory diseases showed a reduction in HGS and gait speed, while a reduction in ASMI was only found in patients with pulmonary TB. Among the sarcopenia indexes, HGS showed the strongest correlation with plasma CAF22, miR-21 and miR-206 levels while ASMI showed the strongest correlation with Dkk-3 and miR-133 in respiratory diseases. We found a modest-to-significant increase in the plasma markers of inflammation, oxidative stress and muscle damage, which had varying degrees of correlations with Dkk-3, CAF22 and selected micro RNAs (miRs) in respiratory diseases. Taken together, our data show that plasma levels of Dkk-3, CAF22 and selected miRs can be useful tools to assess accelerated sarcopenia phenotype in the elderly with respiratory diseases.

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Background: Sarcopenia is a critical finding in patients with chronic heart failure (CHF). However, the search for a definitive biomarker to predict muscle and functional decline in CHF remains elusive. Objectives: We aimed to correlate the circulating levels of selected miRs with the indexes of sarcopenia during healthy aging and in patients with CHF. Methods: We analyzed the association of circulating microRNAs (miRs) levels including miR-21, miR-434-3p, miR424-5p, miR-133a, miR-455-3p and miR-181a with sarcopenia indexes in male, 61-73 years old healthy controls and patients with CHF (N = 89-92/group). Results: Patients with CHF had lower hand-grip strength (HGS), appendicular skeletal mass index (ASMI) and physical capacity than healthy controls. Circulating miR-21 levels were higher and miR-181a, miR-133a, miR-434-3p and miR-455-3p levels were lower in patients with CHF than healthy controls. Among the sarcopenia indexes, HGS showed the strongest correlation with miR-133a while ASMI showed the strongest correlations with miR-133a, miR-434-3p and miR-455-3p. Among the miRs, miR-434-3p showed the highest area under the curve in testing for sensitivity and specificity for CHF. These changes were associated with higher expressions of the markers of inflammation, oxidative stress and muscle damage in CHF patients. Conclusion: Taken together, our data show that circulating miRs can be useful markers of muscle health and physical capacity in the sarcopenic elderly with CHF.

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