New insights into the effects of irisin levels in HIV-infected subjects: correlation with adiposity, fat-free mass, and strength parameters.

OBJECTIVE Patients infected with the human immunodeficiency virus (HIV) have an increased risk of metabolic disorders and alterations on irisin levels. Therefore, the purpose of the current investigation was to quantify the circulating irisin concentration in HIV-infected subjects under highly active antiretroviral therapy and to determine possible correlations between irisin levels with fat mass, fat-free mass, body mass index (BMI), and muscle strength. SUBJECTS AND METHODS Cross-sectional study of 10 men (36.7 ± 11.3 years) and 10 women (42.5 ± 10.3 years) infected with HIV, recruited from the Specialized Service Center in the State Center of Reference for High and Medium Complexity. Blood samples were collected to determine plasma irisin levels, glucose, HDL, total cholesterol, triglycerides, and LDL. Body composition (fat mass, fat-free mass) and anthropometrics (body mass index; BMI) were measured by bioelectrical impedance. Muscle strength was assessed using a mechanic hand dynamometer and one maximum repetition tests. RESULTS Irisin levels correlated positively with fat mass (r = 0.67; p = 0.001) and BMI (r = 0.48; p = 0.036). In contrast, there was an inverse correlation between irisin levels and fat-free mass (r = -0.41; p = 0.008) and five strength parameters: right hand grip (r = -0.46; p = 0.044); left hand grip (r = -0.50; p = 0.027), relative hand grip (r = -0.79; p = 0.001), bench press (r = -0.58; p = 0.009), leg press (r = -0.40; p = 0.085), and biceps curl (r = -0.059; p = 0.009). CONCLUSION Irisin levels correlated positively with body fat and negatively with fat-free mass and strength parameters in HIV-infected patients. Female patients infected with HIV receiving highly active antiretroviral therapy have higher levels of irisin compared with men in a similar circumstance.