Leptin function in hepatocytes protects from hepatic steatosis and protects from hepatic injury, whereas it activates HSCs with the production of α-smooth muscle actin, collagen, and TIMP-1, leading to hepatic fibrosis, and upregulates the expression of TGF-β1 in Kupffer cells [240,241,242]. The gene discussed is LEP; the disease is Hepatic steatosis.