The Role of Interferon Regulatory Factors in Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease with many metabolic comorbidities, such as obesity, diabetes, and cardiovascular diseases. Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, accompanies the progression of hepatic steatosis, inflammation, cell death, and varying degree of liver fibrosis. Interferons (IFNs) have been shown to play important roles in the pathogenesis of NAFLD and NASH. Their regulating transcriptional factors such as interferon regulatory factors (IRFs) can regulate IFN expression, as well as genes involved in macrophage polarization, which are implicated in the pathogenesis of NAFLD and advanced liver disease. In this review, the roles of IRF-involved signaling pathways in hepatic inflammation, insulin resistance, and immune cell activation are reviewed. IRFs such as IRF1 and IRF4 are also involved in the polarization of macrophages that contribute to critical roles in NAFLD or NASH pathogenesis. In addition, IRFs have been shown to be regulated by treatments including microRNAs, PPAR modulators, anti-inflammatory agents, and TLR agonists or antagonists. Modulating IRF-mediated factors through these treatments in chronic liver disease can ameliorate the progression of NAFLD to NASH. Furthermore, adenoviruses and CRISPR activation plasmids can also be applied to regulate IRF-mediated effects in chronic liver disease. Pre-clinical and clinical trials for evaluating IRF regulators in NAFLD treatment are essential in the future direction.