P162 CRITICAL ROLES OF DIETARY SIMPLE SUGARS IN COLITIS PATHOGENESIS

Abstract

The incidence of inflammatory bowel disease (IBD) is strikingly high in Western countries, implicating the role of Western diet in its etiology and pathogenesis. Western diet is characterized by high fat, low fiber, and high sugar. Despite clinical evidence of an association between high sugar diet and IBD susceptibility, the precise role of dietary simple sugars such as glucose, fructose, and sucrose in colitis pathogenesis is unknown. Using dextran sodium sulfate (DSS) and IL10-deficient mouse models of colitis, we studied the effect of simple sugars in colitis susceptibility. Mice were given high glucose, fructose or sucrose in their drinking water or left untreated before and during colitis induced by DSS. Sugar-fed mice exhibited increased colitis susceptibility evidenced by higher body weight loss, diarrhea, rectal bleeding, and severe histopathological changes in the colon as compared to those of sugar-untreated colitic mice. Pre-colitis dietary habit of sugar consumption was critical since sugar pretreated mice were susceptible to DSS-induced colitis even without high sugar diet intake during DSS administration. Consistent with these findings, there were higher incidence of spontaneous colitis development in Il10-/- mice following consumption of high sugar. To understand the underlying mechanism, we evaluated the effect of high sugar diet on intestinal epithelial cell death, inflammation, epithelial barrier permeability, and gut microbiota composition in healthy mice. We did not observe any major pathological changes and apoptosis in the colon of sugar-fed mice. Inflammatory responses, activation of inflammatory signaling pathways, and the expression of tight junction proteins were comparable between control and sugar-fed mice. Interestingly, gut microbiota composition of sugar-fed mice was altered as measured by 16S rRNA gene sequencing of DNA isolated from feces. Microbial species richness was reduced and relative abundance of several bacterial species was either increased or decreased in sugar-fed mice. We further confirmed that sugar-induced alteration of gut microbiota is responsible for exacerbated colitis by using antibiotics or germ-free mice. Mice receiving antibiotics during high-sugar intake did not show increased DSS-colitis susceptibility. Similarly, high-sugar diet did not induce overt colitis pathogenesis in germ-free mice. These findings demonstrate a critical role of dietary caloric sugars in the predisposition and promotion of colitis and could be implicated in the treatment and management of IBD.