Abstract 17268: ApoA-I Mimetic Peptide 4F Suppresses the Elevation of Pro-Inflammatory Lipid Mediators in Mouse Models of Inflammatory Bowel Disease

Abstract

Introduction: Inflammatory bowel disease (IBD) has been linked to an increased prevalence of early stage vascular disease. ApoA-I mimetic peptides including 4F are potential therapeutic agents for the treatment of inflammatory diseases including atherosclerosis, and their mechanism of action appears localized to the intestine. We have reported that 4F protects against the development of disease in both the piroxicam-accelerated IL10-/- and myeloid COX2-/- mouse models of IBD. Hypothesis: We previously reported that plasma and lesion levels of oxidized products of linoleic and arachidonic acid correlate with disease in mouse models of atherosclerosis, and that 4F protects against disease in these models while inhibiting accumulation of these pro-inflammatory mediators. We thus sought to determine the complete lipid pro-inflammatory mediator profiles of both the COX2- and IL10-dependent models of IBD, while also determining the effect of 4F on the pro-inflammatory lipid profiles. Methods: We developed and validated a LC-ESI-MS/MS method for determining the levels of 40 lipid inflammatory mediators in both intestinal tissue and plasma, and we analyzed the effects of both disease and 4F upon these mediators in both IBD models. We also employed Ussing chambers to investigate ex vivo the direct effect of 4F on the clearance of pro-inflammatory lipid mediators from intestinal explants and serosal-side lipoproteins. Results: Disease in both models correlated with significantly elevated tissue and plasma levels of multiple lipid pro-inflammatory mediators, while the protective effects of 4F correlated with the significant suppression of most of these mediators. Of interest, 4F inhibited the disease dependent increase of 15HETE, 12HETE, 5HETE, 13HODE, LTB4, 6ketoPGF1α, PGF2α, and TXB2 in the COX2-/- model; and 15HETE, 12HETE, 13HODE, LTB4, and LTE4 in the IL10-/- model. Ex vivo, we showed that 4F could directly clear the pro-inflammatory mediators from inflamed intestinal explants, while also mediating their trans-intestinal efflux from serosal-side lipoproteins. Conclusions: 4F appears to protect against IBD in part by inhibiting the accumulation of pro-inflammatory lipid mediators, through a mechanism that involves the intestinal clearance of these mediators from tissue and plasma.