Treatment of Hep G2 Cells with Adiponectin Attenuates Fas Expression and Apoptosis

Aims: Fas expression with increased Fas-mediated apoptosis and liver injury are prominent features of fatty liver diseases (NAFLD/ALFD). In contrast, adiponectin is believed to be hepatoprotective. Earlier data of ours suggested that hepatocyte apoptosis plays an important role in liver injury, inflammation, and fibrosis. Based on this concept, our Aim was to ascertain whether adiponectin attenuates long-chain free fatty acid (FFA)-induced Fas expression and, therefore, hepatocyte apoptosis. Methods: Hep G2 cells were cultured for 48h in the presence of 1 mM FFAs (2: 1 oleate: palmitate) and treated with or without adiponectin (25–225 ng/ml). Fas mRNA transcripts were quantified by real-time PCR; results are expressed as a ratio against hypoxanthine phosphoribosyl transferase mRNA and have been normalized to the values of the negative controls. Apoptosis was induced with the huFasL-agonistic CH11 antibody for 2h and quantified by assessing characteristic nuclear alterations by employing the DNA-binding dye 4´6-diamidino–2-phenylindole dihydrochloride. Results: Incubation with FFAs resulted in a significant increase (p<0.01) of Fas mRNA transcripts compared to controls. FFAs-induced Fas mRNA transcription was up to 10-fold downregulated in the presence of adiponectin in a dose- dependent manner. In the absence of FFAs however, adiponectin did not considerably effect Fas expression. The percentage of CH11-induced apoptosis in steatotic hepatocytes was significantly reduced in cells incubated with adiponectin as opposed to cells without treatment (60% vs. 20% ;p<0.01). Conclusion: Adiponectin may be heaptoprotective due to the attenuation of Fas. Administration of adiponectin may thus open up new therapeutic options for treating hepatic steatosis and Fas-mediated liver injury.