TNF and irritable bowel syndrome: Mechanically, pre-clinical evidence highlights VNS as a multifaceted therapy for IBS, including reducing inflammation via α7 nicotinic acetylcholine receptor-mediated suppression of TNF-α, alleviating visceral hypersensitivity, increasing colorectal distension thresholds, enhancing motility through M3 receptor activation and gastric emptying, restoring gut microbiota diversity via elevating bifidobacterium abundance and short-chain fatty acids, and improving intestinal barrier integrity.