Background and Aim: Non-alcoholic fatty liver disease (NAFLD) is characterised by lipid deposition in hepatocytes. Hepatic lipid accumulation is known to drive inflammation and oxidative stress, ultimately leading to the development of insulin resistance. The aim of this study was to assess the effects of a nitroxide, TEMPOL, on HepG2 cellular steatosis and inflammation induced by palmitic acid (PA).
Methods and results: To assess the effects of TEMPOL, HepG2 were exposed to PA for 24 hours before exposure to TEMPOL (200mM, 500mM, 1mM, 2mM) for 5 hours. The effects of PA induced-cellular steatosis and inflammation were then assessed using an (i) oil red O staining and extraction method to assess lipid accumulation, (ii) MTT assay to detect cell viability, (iii) RT-qPCR to assess the mRNA gene expression level of inflammatory markers, (iv) seahorse mitochondrial kit to assess mitochondrial dysfunction, (v) dichlorofluorescein assay to assess reactive oxygen species (ROS) levels and a (iv) glycogen assay to assess glycogen levels. The results show HepG2 exposed to TEMPOL reduced palmitic acid induced- (i) lipid accumulation, (ii) inflammation, (iii) insulin-mediated glycogenesis, (iii) mitochondrial oxidative stress and (iv) reactive ROS levels with no effect on cell viability.
Conclusions: These findings suggest that TEMPOL plays a protective role in PA-induced hepatic steatosis that is associated with reduced hepatic inflammation, oxidative stress and insulin-mediated glycogenesis, thus indicating TEMPOL may be useful as a pharmaceutical therapy for improving hepatic steatosis and insulin sensitivity in type 2 diabetes.