TGF-β1 contributes to the hepatic inflammation in animal models with nonalcoholic steatohepatitis by Smad3/TLR2 signaling pathway

Non-alcoholic fatty liver disease (NAFLD) is increasingly affecting human health and the economy worldwide due to various factors. Here, we found that the expression of TGF-β1 and TLR2 was significantly up-regulated in liver samples from both rats and mice nonalcoholic steatohepatitis (NASH) models. By constructing corresponding cell model, we found that TGF-β1 challenge can positively regulate the expression of TLR2 and p-Smad2/3, and the dual luciferase reporter gene system and EMSA assay confirmed the existence of Smad3 binding site (-916 ∼ -906) in the promoter region of TLR2. The overexpression and interference changes of Smad2/3 further verified the above experimental results. Taken together, these findings suggest that TGF-β1 promotes TLR2 transcription and its target gene expression via Smad3, leading to malignant exacerbation of liver inflammation in NASH, which provides new insights into the treatment of NASH.