AHR and colitis: In colitis models induced by dextran sulfate sodium, Enterobacteriaceae species were responsible for recruiting Ly6hiCCR2+ monocytes in the blood.[45] Other studies showed that the gut microbiota affects intestinal macrophages directly by releasing metabolites or bacterial components, such as bile acids, aryl hydrocarbon receptor (AhR) ligands, short-chain fatty acids (SCFAs), urolithin A, LPS, and bacteria hemolysin.