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The effect of dietary lipids on colitis

University of British Columbia

Inflammatory Bowel Diseases (IBD) are a major concern in the developed world such as North America and Europe. It has been speculated that diet is an important risk factor in triggering IBD, as well as in inducing symptoms in IBD patients. However, to date no single nutrient has been confirmed empirically as either a contributing factor, or conversely, a preventative factor, that can protect against the disease. The main objective of this project was to determine the effects of dietary lipids on intestinal inflammation in vivo and in vitro before and during colitis. To achieve this, I studied high fat diets (HFD) : n-6 PUFA, MUFA and SFA and studied each of these HFD supplemented with n-3 PUFA. The mice, after 5 weeks of eating the lipid diets, were orally gavaged with an enteric pathogen Citrobacter rodentium commonly used to induce intestinal inflammation found during colitis. I determined the effects of different dietary oils on the intestinal immune responses by quantifying infiltration of immune cells and examining colonic, serum cytokine and chemokine responses. Since I had previously found that intestinal alkaline phosphatase (IAP) played a role in survival during infection induced colitis, I examined expression and activity of IAP in vivo and in vitro using 264.7 RAW (Mouse leukaemic monocyte macrophage) and Caco-2 (human epithelial colorectal adenocarcinoma) cells stimulated with various fatty acids and lipopolysaccharides (LPS). Overall my results showed that mice fed MUFA rich diets and inflicted with colitis were the most protected, whereas mice fed n-6 PUFA and SFA had exacerbated colitic responses compared to uninfected mice. Mice fed SFA diets and inflicted with colitis had increased compensating protective homeostatic responses such as: IL-10, IL-33, Reg3γ and T regulatory cells. The n-6 PUFA supplemented with n-3 PUFA diets resulted in a negative outcome on the host immune response in mice. In contrast, MUFA and SFA diets supplemented with n-3 PUFA had no effect on immune responses in mice. In conclusion, I recommend that people suffering from IBD should not supplement n-6 PUFA diets with n-3 PUFA. IBD patients should consider a diet rich in MUFA and/or SFA diets.

Text

2015-02-05

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/52062

Biology

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/