FNDC5 and metabolic dysfunction-associated steatotic liver disease: Long-term exercise-induced irisin or supplementation of exogenous r-irisin could protect the liver from non-alcoholic fatty liver disease (NAFLD) (6, 7), liver glucose disorder (29, 30), or I/R-induced liver injury (31), which embodied the potential role of irisin in muscle-liver cross-talk (32).