Gut microbiota dysbiosis (e.g., altered Firmicutes/Bacteroidetes ratio) increases endotoxin (LPS) translocation into circulation, triggering immune responses via Toll-like receptor 4 (TLR4), promoting systemic low-grade inflammation, and affecting bile acid metabolism and short-chain fatty acid (SCFA) production, thereby further exacerbating metabolic abnormalities in MetS (31). This evidence concerns the gene TLR4 and metabolic syndrome.