Emerging roles of metabolites of ω3 and ω6 essential fatty acids in the control of intestinal inflammation

The gastrointestinal tract is continuously exposed to the external environment, which contains numerous non-self antigens, including food materials and commensal micro-organisms. For the maintenance of mucosal homeostasis, the intestinal epithelial layer and mucosal immune system simultaneously provide the first line of defense against pathogens and are tightly regulated to prevent their induction of inflammatory responses to non-pathogenic antigens. Defects in mucosal homeostasis lead to the development of inflammatory and associated intestinal diseases, such as Crohn's disease, ulcerative colitis, food allergy and colorectal cancer. The recent discovery of novel dietary omega 3 and omega 6 lipid-derived metabolites-such as resolvin, protectin, maresin, 17,18-epoxyeicosatetraenoic acid and microbe-dependent 10-hydroxy-cis-12-octadecenoic acid-and their potent biologic effects on the regulation of inflammation have initiated a new era of nutritional immunology. In this review, we update our understanding of the role of lipid metabolites in intestinal inflammation.