Research Status of Irisin in Improving Hepatic Lipid Metabolism Disorder and Reducing NAFLD

Nonalcoholic fatty liver disease (NAFLD) does great harm to human health, and the incidence is increasing year by year. The liver serves an important role in lipid metabolism. Hepatic steatosis develops as a consequence of lipid metabolic dysregulation, namely the imbalance among fatty acid uptake, de novo lipogenesis (DNL), fatty acid oxidation (FAO) and very low density lipoprotein-mediated lipid export. With diverse health-promoting effects, exercise is a cheap and effective intervention for the prevention and treatment of NAFLD. Amelioration of impaired lipid metabolism acts as an important mechanism by which exercise protects against NAFLD. However, how exercise ameliorates lipid metabolic dysregulation is still unclear. Skeletal muscle is not only a vital organ of motion, but also has an endocrine function, it secretes numerous myokines which mediates exercise-induced benefits on our body. Irisin is a small peptide derived from proteolytic cleavage of fibronectin type III domain containing protein 5 (FNDC5). As a myokine, its production is regulated by exercise and it play an important role in exercise-induced protection against obesity-related chronic diseases, such as NAFLD. A growing body of research has demonstrated that Irisin ameliorates lipid metabolic dysregulation in NAFLD. Irisin mediated inhibition of hepatic DNL and FAO has been reported. However, the effect of Irisin on fatty acid uptake and lipid export is still unknown. In the present review, we summarized the researches focusing on how exercise regulated Irisin production and the effect of Irisin on lipid metabolism on NAFLD. To clarify the above problems will help us to better understand the role of Irisin on exercise-mediated protection against NAFLD.