Protectin D1n-3 DPA and resolvin D5n-3 DPA are effectors of intestinal protection

The resolution of inflammation is an active process orchestrated by specialized proresolving lipid mediators (SPM) that limit the host response within the affected tissue; failure of effective resolution may lead to tissue injury. Because persistence of inflammatory signals is a main feature of chronic inflammatory conditions, including inflammatory bowel diseases (IBDs), herein we investigate expression and functions of SPM in intestinal inflammation. Targeted liquid chromatography-tandem mass spectrometry-based metabololipidomics was used to identify SPMs from n-3 polyunsaturated fatty acids in human IBD colon biopsies, quantifying a significant upregulation of the resolvin and protectin pathway compared with normal gut tissue. Systemic treatment with protectin (PD)1(n-3 DPA) or resolvin (Rv)D5(n-3 DPA) protected against colitis and intestinal ischemia/reperfusion-induced inflammation in mice. Inhibition of 15-lipoxygenase activity reduced PD1(n-3 DPA) and augmented intestinal inflammation in experimental colitis. Intravital microscopy of mouse mesenteric venules demonstrated that PD1(n-3 DPA) and RvD5(n-3 DPA) decreased the extent of leukocyte adhesion and emigration following ischemia-reperfusion. These data were translated by assessing human neutrophil-endothelial interactions under flow: PD1(n-3 DPA) and RvD5(n-3 DPA) reduced cell adhesion onto TNF-alpha-activated human endothelial monolayers. In conclusion, we propose that innovative therapies based on n-3 DPA-derived mediators could be developed to enable antiinflammatory and tissue protective effects in inflammatory pathologies of the gut.