NAFLD and NASH are increasingly recognized as leading causes of liver fibrosis. The pathogenesis involves insulin resistance, lipid accumulation in hepatocytes, oxidative stress, and chronic inflammation. TGF-β plays a pivotal role in driving fibrosis in NASH by inducing the transformation of HSCs into myofibroblasts. TNF-α also contributes to inflammation and hepatocyte injury in NAFLD/NASH. This evidence concerns the gene TNF and metabolic dysfunction-associated steatohepatitis.