Gut-derived bacterial products such as endotoxin (lipopolysaccharides, LPS) and bacterial DNA are delivered to the liver through the portal vein and activate toll-like receptors (TLRs), mainly TLR4 and TLR9, and their down-stream cytokines and chemokines, leading to the development and progression of NAFLD. Here, TLR4 is linked to metabolic dysfunction-associated steatotic liver disease.