Associação dos níveis plasmáticos da irisina com a interleucina-6, a massa e a força muscular em idosos comunitários: um estudo de base populacional

Abstract

Aging is associated with the development of a systemic state of low-grade chronic inflammation and decline of muscle mass and strength. Irisin is secreted by skeletal muscle and acts to negatively modulate chronic inflammation and improved skeletal muscle adaptations. The aim of this study was to evaluate associations of irisin plasma concentrations with interleukin-6 (IL-6), muscle mass and strength. The study sample consisted of individuals with 60 years or older, without cognitive disorders, enrolled in the Family Health Strategy of Alfenas/MG. A structure questionnaire weas used to collect sociodemographic, clinical and lifestyle information’s. Plasma levels of irisin and IL-6 were assessed by enzyme-linked immunosorbent assay (ELISA). The prediction equation anthropometric for muscle mass proposed by Lee et al was used to generate estimates of appendicular skeletal muscle mass index (ASM). The handgrip strength (HGS) was measured using the Jamar dynamometer. Correlation between irisina plasma levels and interleukin-6, muscle mass and strength were verified by Spearman correlation coefficient. A multivariate logistic regression model was performed to assess the relationship between the variables, considering α ≤ 0.05. The study was approved by the Research Ethics Committee, Opinion 722,155 (CAAE: 32269614.0.0000.5142). The study included 406 older adults. Irisin plasma concentration was higher in men compared to women (4.11 ± 11.25 vs 2.56 ± 2.82 ng/mL), but without significant differences (p=0.784). Irisin concentrations were significantly lower in older adults with 74 years or older compared to over 74 years old (3.71 ± 7.04 ng/dL vs 4.01 ± 13.67 ng/dL; p=0.191). Irisin levels showed significant positive correlation with IL-6 (r=0.585; p<0.005). Higher serum irisin were positively associated with higher serum IL-6 concentrations in crude model (p=0.002 and CI 0.350; 0.795) and irisin remained significantly associated with Il-6 even after adjustment for gender, age, comorbidities, BMI, ASM, HGS, gait speed, SPPB score and level of physical activity (p=0.001 and CI 0.331; 0.763). Irisin levels were not associated with muscle mass or strength (p>0.005). In this study, circulating irisin levels showed a significant association with IL-6, but not with skeletal muscle mass and strength.