Effects of IL-6 and gp130 on Gene Expression and Production of Mitochondrial Biogenesis Markers in HepG2 Cell Oxidative Stress Models

Objective: The dualistic role of IL-6 in diseases associated with metabolic disorders (including non-alcoholic fatty liver disease, NAFLD) under oxidative stress has been repeatedly demonstrated in various studies. The aim of this work was to investigate the combined effect of IL-6 and glycoprotein 130 (gp130) on cell death pathways and mitochondrial dynamics in the HepG2 cell line in the oxidative stress model. Methods: The HepG2 cell line was used to create a model of oxidative stress in hepatocytes (hepatocytes without any additives are hereafter referred to as control) by adding tert-butyl hydroperoxide (tBHP). IL-6 (variant 1) or IL-6 + gp130 (variant 2) were added to the experimental model of oxidative stress. Cell viability was determined by flow cytometry and the expression and production of key markers of mitochondrial biogenesis, apoptosis, mitophagy and antioxidant defense were analyzed by RT-qPCR and Western blotting, respectively. Results and Discussion: The addition of IL-6 alone (variant 1) increased the relative percentage (%) of viable cells and decreased the number of dead and apoptotic cells. In the cell model, IL-6 contributed to an increase in the expression of the TFAM, MFN2, DNM1L and NF-kB1 genes and the production of MFN2 protein and, on the contrary, led to a decrease in the expression of HSP70, HSF1, BCL2L1 and SQSTM1. The addition of gp130 + IL-6 to the model of oxidative stress in hepatocytes (variant 2) increased the expression of the genes TFAM, MFN2, DNM1L, NF-kB1 and MAPLC3B, while the expression of HSP70, HSF1 and BCL2L1 decreased. Conclusions: Addition of IL-6 to the model of oxidative stress in hepatocytes promotes activation of mitochondrial dynamics, decreases apoptosis and stimulates cell viability, while gp130 mediates stimulation of the expression of genes responsible for mitoautophagy.