Sitagliptin attenuates methionine/choline-deficient diet-induced steatohepatitis

Abstract

Aims: Accumulating evidence suggests that inhibitors of dipeptidyl peptidase-4 (DPP-4), such as sitagliptin, may play an important role in the prevention of non-alcoholic steato- hepatitis (NASH). This study was conducted to elucidate whether sitagliptin could prevent steatohepatitis by inhibiting pathways involved in hepatic steatosis, inflammation, and fibrosis. Methods: C57BL/6 mice were fed a methionine/choline-deficient (MCD) diet with or without supplement with sitagliptin for 5 weeks. Liver and adipose tissue from mice were examined histologically and immunohistochemically to estimate the effect of sitagliptin on the development of NASH. Results: Supplementation with sitagliptin resulted in significant improvement of MCD dietinduced fat accumulation in the liver. In addition, sitagliptin treatment lowered fatty acid uptake, expression of VLDL receptor and hepatic triglyceride content. Sitagliptin also effectively attenuated MCD diet-induced hepatic inflammation, endoplasmic reticulum (ER) stress, and liver injury, as evidenced by reduced proinflammatory cytokine levels, ER stress markers, and TUNEL staining. Expression of CYP2E1 and 4NHE were strongly increased by the MCD diet, but this effect was successfully prevented by sitagliptin treatment. Furthermore, sitagliptin significantly decreased levels of MCD diet-induced fibrosisassociated proteins such as fibronectin and a-SMA in the liver. Inflammatory and atrophic changes of adipose tissue by MCD diet were restored by sitagliptin treatment. *