Permanently increased mucosal permeability in patients with backwash ileitis after ileoanal pouch for ulcerative colitis

Abstract

Objective. Backwash ileitis (BI) has not been identified as a risk factor for pouchitis. The aim of this study was to investigate the barrier function of the ileoanal pouch depending on the presence of BI. The incidence of pouchitis in a population of ulcerative colitis patients with BI is also reported. Material and methods. Biopsies were taken from 80 patients with ulcerative colitis: a) terminal ileum prior to pouch creation (pre-IAP); b) 16 months after ileostomy closure (intact pouch); and c) during pouchitis. Patients were stratified into the BI group and the non-BI (ØBI) group. Barrier function was determined in Ussing-chambers as epithelial resistance by impedance analysis and as mannitol permeability from ³H-mannitol fluxes. Na⁺-glucose co-transport was measured as a change in short-circuit current (I_SC) after addition of glucose. Relative risk of developing pouchitis was calculated by corrected χ² test. Results. In 13/21 (BI/ØBI) pre-IAP patients, 23/37 (BI/ØBI) with an intact pouch, and 35/7 (BI/ØBI) with pouchitis, epithelial resistance in BI/ØBI was 13.5±1.6/14.3±0.9 Ω·cm² for pre-IAP, 12.7±1.3/16.8±1.2 Ω·cm² (p<0.05 BI versus ØBI) for the intact pouch, and 10.1±1.1/9.9±1.8 Ω·cm² for pouchitis (p<0.05 BI versus ØBI with an intact pouch). No differences were found for electrogenic chloride secretion and active Na⁺-glucose co-transport between BI/ØBI in the three groups. In patients with BI, pouchitis was more common (35 versus 7 patients, odds ratio 33.0 (95% CI 8.3–143.9; p<0.0001)). Conclusions. Ulcerative colitis patients with BI show impaired barrier function in the further course of the ileoanal pouch. Thus, BI has a long-term impact on epithelial barrier function.

• Active transport
• biopsy
• mannitol permeability
• pouchitis
• transepithelial resistance
• ulcerative colitis