Triglyceride peroxidation progression in lipid droplets of hepatocytes in nonalcoholic steatohepatitis

Objective: Nonalcoholic steatohepatitis is a chronic liver disease caused by the progression of hepatocellular death and inflammation from simple steatosis. However, the pathogenesis of this disease remains unclear. Lipid peroxidation is one of the most critical factors in the development of nonalcoholic steatohepatitis; however, oxidised lipids – the products of lipid peroxidation – are insufficiently analysed. Here, we comprehensively analysed oxidised lipids in the liver during nonalcoholic steatohepatitis development in a choline-deficient, l-amino acid-defined, high-fat diet-fed mouse model. Methods: Liver from C57BL/6J mice, fed a standard diet or a choline-deficient l-amino acid-defined high-fat diet for 1, 3, or 6 weeks, were collected to evaluate fibrosis, steatosis, inflammation, liver injury, and oxidised lipid production and to observe the suppression of these parameters upon vitamin E administration. In addition, organellar localisation of lipid peroxidation was assessed using fluorescence imaging. Finally, a mitochondria-targeted antioxidant was administered to model mice to investigate the mechanism underlying lipid peroxidation. Results: We found an accumulation of oxidised triglycerides in the early stages of nonalcoholic steatohepatitis. Furthermore, our data indicate that oxidised triglycerides are generated by lipid peroxidation in lipid droplets due to mitochondria-derived reactive oxygen species.