Recent evidences have demonstrated a close correlation between the alteration of gut microbiota (dysbiosis) and NASH development due to the increased intestinal permeability to lipopolysaccharide (LPS) that activates Toll-like receptor 4 (TLR4) of hepatic Kupffer cells (KCs) and hepatic stellate cells (HSCs), triggering the pro-inflammatory cytokine cascade that induces and maintains NASH. This evidence concerns the gene TLR4 and metabolic dysfunction-associated steatohepatitis.