Fig. 3

SCFAs alleviate IBD and CRC by increasing intestinal barrier function and reducing endotoxin levels in the blood. SCFAs increase the intestinal barrier function, reduce the entry of lipopolysaccharide (LPS) into the blood, induces naive T cells to differentiate into Tregs, inhibit the production of tumour necrosis factor-alpha (TNF-α) and interleukin (IL)-6 by intestinal macrophages, and inhibit the production of IL-8 by normal intestinal epithelial cells (IECs) to alleviate inflammation. Butyrate promotes CRC cell apoptosis by inhibiting C-AMP/P38-MAPK and increasing Bax/Bcl-2 ratio. Other abbreviations are: SCFA: short-chain fatty acid; GPCR: G protein-coupled receptor; FFAR: free fatty acid receptor; IBD: inflammatory bowel disease; CRC: colorectal cancer; AKT: protein kinase B; TLR4: Toll-like receptors 4; and HDACi: histone deacetylase inhibitor