Circulating adiponectin expression is elevated and associated with the IL-15/IL-15Rα complex in obese physically active humans.

Abstract

Adiponectin is an adipokine with oxidative, anti-inflammatory and antiatherogenic effects in several peripheral tissues; however, circulating adiponectin expression is reduced in cardio-metabolic diseases. The aim of this study was to ascertain whether regular physical activity mediates circulating adiponectin concentrations at baseline in an obese population. Two hundred and twenty-one obese participants were divided into 6 groups according to gender, physical activity (PA), and type 2 diabetes mellitus (T2DM) diagnosis: A and B) obese PA females (N.=28) and males (N.=33); C and D) obese non-PA females (N.=40) and males (N.=40); E and F) obese non-PA females (N.=40) and males (N.=40) with T2DM. Serum adiponectin, IL-15 and IL-15Rα, blood glucose/lipid profile, and body composition were measured. Circulating adiponectin increased in PA participants compared to non-PA (ANOVA, P=0.001), finding higher concentrations in females compared to males (P<0.001), particularly in the PA group (P=0.005). Serum adiponectin was associated with age (R2=0.068), body mass (R2=-0.108), waist circumference (WC) (R2=-0.122), LDL (R2=-0.045), triglycerides (R2=-0.043), and serum IL-15Rα (R2=-0.243), as well as fat mass in females (R2=0.098), and WC in males (R2=0.112). Circulating adiponectin increased in obese PA participants (≥180 min/week) compared to non-PA counterparts, indicating that physical activity may mediate baseline adiponectin levels irrespective of the fat mass regulatory effect. The inverse relationship found between serum adiponectin and IL-15Rα may support the regulative role of the IL-15/IL-15Rα complex on this adipokine at baseline.