RESUMO
BACKGROUND: A total of 10-15% of patients with an ileoanal pouch develop severe pouchitis necessitating long-term use of antibiotics or pouch excision. Probiotics reduce the risk of recurrence of pouchitis, but mechanisms behind these effects are not fully understood. AIM: To examine mucosal barrier function in pouchitis, before and after probiotic supplementation and to assess composition of mucosal pouch microbiota. METHODS: Sixteen patients with severe pouchitis underwent endoscopy with biopsies of the pouch on three occasions: during active pouchitis; clinical remission by 4 weeks of antibiotics; after 8 weeks of subsequent probiotic supplementation (Ecologic 825, Winclove, Amsterdam, the Netherlands). Thirteen individuals with a healthy ileoanal pouch were sampled once as controls. Ussing chambers were used to assess transmucosal passage of Escherichia coli K12, permeability to horseradish peroxidase (HRP) and 5¹Cr-EDTA. Composition and diversity of the microbiota was analysed using Human Intestinal Tract Chip. RESULTS: Pouchitis Disease Activity Index (PDAI) was significantly improved after antibiotic and probiotic supplementation. Escherichia coli K12 passage during active pouchitis [3.7 (3.4-8.5); median (IQR)] was significantly higher than in controls [1.7 (1.0-2.4); P < 0.01], did not change after antibiotic treatment [5.0 (3.3-7.1); P = ns], but was significantly reduced after subsequent probiotic supplementation [2.2 (1.7-3.3); P < 0.05]. No significant effects of antibiotics or probiotics were observed on composition of mucosal pouch microbiota; however, E. coli passage correlated with bacterial diversity (r = -0.40; P = 0.018). Microbial groups belonging to Bacteroidetes and Clostridium clusters IX, XI and XIVa were associated with healthy pouches. CONCLUSIONS: Probiotics restored the mucosal barrier to E. coli and HRP in patients with pouchitis, a feasible factor in prevention of recurrence during maintenance treatment. Restored barrier function did not translate into significant changes in mucosal microbiota composition, but bacterial diversity correlated with barrier function.
