Oleic acid, hydroxytyrosol and n-3 fatty acids collectively modulate colitis through reduction of oxidative stress and IL-8 synthesis; in vitro and in vivo studies

Our recent study has demonstrated that medium chain triglycerides (MCT) and monounsaturated fatty acids potentiate the beneficial effects of fish oil on risk factors of cardiovascular disease. In the present study, we have investigated the influence of MCT or olive oil on the protective and mucosal healing ability of fish oil in ulcerative colitis using cell simulation and animal models. Caco-2 cells grown in medium chain fatty acids enriched medium has exaggerated t-butyl hydroperoxide induced cell damage, GSH depletion, and IL-1 beta induced IL-8 synthesis, compared to the cells grown in oleic acid & hydroxytyrosol (OT) enriched medium. Further, combined treatment of cells with eicosapentaenoic acid, docosahexaenoic acid, and OT has remarkably attenuated the cell damage, and IL-8 synthesis, compared to individual treatments. To evaluate the effect of these lipid formulations in vivo, adult Wistar rats were fed diet enriched with high amount of medium chain triglycerides (MCT), virgin olive oil, or their combination with fish oil. Colitis was induced in rats using dextran sulfate sodium (DSS) for 7days followed by 10-days of recovery period. Rats of MCT group exhibit severe disease activity, higher levels of inflammatory cytokines in the colon compared to the olive oil group. Furthermore, there was persistent body weight loss, loose stools, higher levels of inflammatory cytokines in the rats of MCT group, even after DSS was withdrawn from drinking water. Conversely, fish oil has remarkably attenuated the DSS induced alterations in both MCT and olive oil diet groups with significantly greater effect in the olive oil group. Thus, MCT increase the susceptibility to colitis through oxidative damage and IL-8 synthesis in intestinal epithelial cells. The beneficial effects of virgin olive oil could be partially attributed to hydroxytyrosol. Combined treatment of hydroxytyrosol, oleic acid and n-3 fatty acids exhibit huge therapeutic benefits in colitis. (C) 2016 Elsevier B.V. All rights reserved.