Modulation of intestinal microbiota by non-digestible carbohydrates may reduce inflammation in inflammatory bowel disease (IBD). The aim of the present study was to assess the effects of inulin and fructo-oligosaccharides (FOS) on intestinal microbiota and colitis in HLA-B27 transgenic rats, a well-validated rodent model for IBD. In this study, 4-week-old rats were fed 8 g/kg body weight inulin or FOS for 12 weeks, or not. Faeces were collected at 4 and 16 weeks of age; and caecal samples were collected at necropsy. The effects of inulin and FOS on chronic intestinal inflammation were assessed using a gross gut score, histology score and levels of mucosal IL-1β. Intestinal microbiota were characterised by quantitative PCR and denaturing gradient gel electrophoresis. Colitis was significantly reduced in all FOS-fed rats compared to the control diet, whereas inulin decreased chronic intestinal inflammation in only half the number of animals. Quantitative analysis of caecal microbiota demonstrated that inulin increased the numbers of total bacteria and theBacteroides-Prevotella-Porphyromonasgroup, FOS increased bifidobacteria, and both fructans decreasedClostridiumcluster XI. In the faecal samples, both inulin and FOS decreased total bacteria,Bacteroides-Prevotella-Porphyromonasgroup, andClostridiumclusters XI and XIVa. FOS increasedBifidobacteriumspp., and mediated a decrease of gene copies of Enterobacteriaceae andClostridium difficiletoxin B in faeces. SCFA concentrations in the faecal and caecal samples were unaffected by the diets. In conclusion, FOS increased the abundance ofBifidobacteriumspp., whereas both fructans reducedClostridiumcluster XI andC. difficiletoxin gene expression, correlating with a reduction of chronic intestinal inflammation.
Inulin and fructo-oligosaccharides have divergent effects on colitis and commensal microbiota in HLA-B27 transgenic rats