Exercise suppresses NLRP3 inflammasome activation in mice with diet-induced NASH: a plausible role of adropin

NLRP3 inflammasome activation, which can be triggered by reactive oxygen species (ROS), contributes to nonalcoholic steatohepatitis (NASH) progression. Exercise is an effective therapeutic strategy for NASH. However, whether exercise prevents NLRP3 activation in NASH has not been investigated. Here, we investigated the effect of exercise on NLRP3 inflammasome in mice with high-fat diet (HFD)-induced or methionine and choine-deficient (MCD) diet-induced NASH and explored whether adropin, a metabolic peptide hormone shown to inhibit inflammation, mediates an exercise-induced benefit against NLRP3 inflammasome activation. Exercise alleviated diet-induced hepatic steatosis, inflammation, and fibrosis. Importantly, exercise significantly reduced the expression of NLRP3 inflammasome components, decreased Caspase-1 enzymatic activity, normalized IL-1β production, and suppressed ROS overproduction in HFD-fed and MCD diet-fed mice. The exercise-elicited NLRP3 inflammasome inhibition was accompanied by increased adropin levels. Moreover, serum adropin levels were negatively correlated with serum IL-1β levels. We further explored the effect of adropin on the NLRP3 inflammasome in palmitic acid (PA)-treated hepatocytes and Kupffer cells. Although adropin treatment did not significantly decrease the levels of all inflammasome components, it reduced the active Caspase-1 level, decreased Caspase-1 activity and downregulated IL-1β expression in hepatocytes and Kupffer cells (KCs) treated with PA. Moreover, ROS levels in PA-stimulated hepatocytes and Kupffer cells were reduced upon adropin treatment. In summary, we demonstrated that the inhibitory effect of exercise on NLRP3 inflammasome activation was associated with adropin induction, resulting in NASH improvement. This study shows that exercise increases adropin levels and inhibits NLRP3 inflammasome activation in mice with diet-induced nonalcoholic steatohepatitis (NASH). Furthermore, adropin suppresses palmitic acid-induced NLRP3 inflammasome activation in hepatocytes and Kupffer cells. These results indicate that exercise may inhibit NLRP3 inflammasome activation via adropin induction, resulting in NASH improvement.