Evaluating the effect of a mixture of two main conjugated linoleic acid isomers on hepatic steatosis in HepG2 cellular model

Hepatic steatosis is an early form of non-alcoholic fatty liver disease (NAFLD), caused by abnormal fat deposition in the hepatocytes. Conjugated linoleic acid (CLA) is a group of positional and geometric dienoic isomers of linoleic acid that attract significant attention because of its beneficial effects on chronic diseases such as cancer, obesity, and metabolic syndrome. This study examined the influence of a mixture of two main CLA isomers (CLA-mix) on lipid accumulation and lipid metabolism-related genes using HepG2 cells treated with palmitic acid (PA) as an in vitro model for hepatic steatosis. Methods and Results: HepG2 cells were treated for 24 h: control (BSA), model (BSA + PA), and treated groups (BSA-PA + non-toxic concentrations of CLA-mix). Intracellular lipid deposition, triglyceride (TG), total cholesterol (TC) and gene expression were measured by Oil-Red O staining, colorimetric assay kits and real-time PCR, respectively. CLA-mix at high concentrations had significantly decreased intracellular total lipid and TG deposition compared to the model group. However, none of the CLA-mix concentrations had a significant effect on the intracellular TC level. CLA-mix significantly increased the expression of some genes mainly regulated by PPARα but did not alter the expression of lipogenesis-related genes. Conclusions: These results demonstrate that high concentrations of CLA-mix protect against hepatic steatosis and play a role in regulating fatty acid oxidation and bile excretion through the PPARα pathway. It is suggested that the effect of different ratios of two main CLA isomers on the amount and ratio of bile compounds be investigated in future studies. Graphic abstract