Effects of chronic exercise on cytokine production in white adipose tissue and skeletal muscle of rats.

White adipose tissue (WAT) is a major source of production of cytokines involved in chronic diseases such as obesity, type 2 diabetes, and atherosclerosis. Long-term exercise has been proposed as a therapy to reduce chronic inflammation. We investigated here the influence of an intense exercise training (over 7 weeks) on several cytokine concentrations including interleukin 1 receptor antagonist (IL-1ra), IL-1beta, and IL-12 in serum, WAT, and skeletal muscle (SM) from non-obese rats. Two groups of 10 rats were investigated: one group was progressively trained (the two last weeks: 120min per day, 25m/min, 7% grade, 5 days per week) and the other age-matched group was used as a sedentary control. Compared to sedentary rats, weight gain was lower in the trained rats (P<0.01). In WAT, concentrations of IL-1ra, IL-1beta, and IL-12 were lower (P<0.001 for IL-1ra and IL-12, P<0.05 for IL-1beta) while they were higher in SM (P<0.01 for IL-1ra, P<0.001 for IL-1beta, P<0.05 for IL-12), and similar in serum. Significant correlations were noted between (i) body weight and WAT concentrations of IL-1ra, IL-1beta, and IL-12 (0.595, 0.450, and 0.481, respectively), (ii) body weight and IL-1beta concentration in SM (-0.526). We also observed significant negative correlations between WAT and SM concentrations of the three cytokines. We show here for the first time that intense exercise training with weight loss reduced concentrations of IL-1ra, IL-1beta, and IL-12 in WAT, while it increased them in SM. These results suggest that exercise could help reduce inflammation in WAT through mobilization of immune cells producing pro- and anti-inflammatory cytokines in SM.