Dietary extra virgin olive oil polyphenols supplementation modulates DSS-induced chronic colitis in mice

We evaluated the protective effect of dietary extra virgin olive oil (EVOO) polyphenol extract (PE) supplementation in the inflammatory response associated to chronic colitis model. Six-week-old mice were randomized in four dietary groups: standard diet (SD), EVOO diet and both enriched with PE (850 ppm) (SD +PE and EVOO+PE). After 30 days, animals that were exposed to dextran sodium sulfate (DSS) (3%) followed by 3 weeks of drinking water developed chronic colitis, which was evaluated by disease activity index (DAI) and histology. Cell proliferation was analyzed by immunohistochemical and changes in monocyte chemotactic protein (MCP)-1 and tumor necrosis factor (TNF)-alpha mRNA expression by quantitative real-time polymerase chain reaction. Colonic expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, mitogen-activated protein kinases (MAPKs), I kappa B alpha inhibitory and peroxisome proliferator-activated receptor gamma (PPAR gamma) were determined by western blotting. SD-DSS group showed a significant increase of DAI, histological damage and cell proliferation, as well as an up-regulation of TNF-alpha, MCP-1, COX-2 and iNOS proteins. p38 and INK MAPKs phosphorylation, I kappa B alpha degradation and PPAR gamma deactivation were also observed. However, in DSS-treated and EVOO+PE-fed mice, DAI and cell proliferation were significantly reduced, as well as MCP-1, TNF-alpha, COX-2 and iNOS expression levels. In addition, this dietary group, notably down-regulated JNK phosphorylation, prevented I kappa B alpha degradation and PPAR gamma deactivation. These results demonstrated, for the first time, that EVOO-PE supplementation possessed marked protective effects on experimental colitis through PPAR gamma up-regulation and nuclear transcription factor-kappa B and MAPK signaling pathway inhibition, decreasing the inflammatory cascade. We concluded that PE-enriched EVOO diet could be a beneficial functional food on ulcerative colitis. (C) 2013 Elsevier Inc. All rights reserved.