Abstract

Background and aims: Little is known of the permeability of ileoanal pouches. Hence the aim of the present study was to determine changes in permeability and mucosal function after ileo-pouchanal anastomosis (IPAA) in patients with ulcerative colitis.

Materials and methods: Biopsies were taken from 43 patients (male:female ratio 28:15; mean age 35.2 (12.5) years) prior to colectomy (ileum prior to pouch), prior to closure of ileostomy (deviation), and after closure of ileostomy (intact pouch) in the case of pouchitis, and from 14 healthy controls. Tissues were mounted in a miniaturised Ussing chamber. Epithelial and subepithelial resistance was determined by transmural impedance analysis. Active Na⁺-glucose cotransport was measured as change in short circuit current after stepwise addition of glucose, and active Cl⁻ secretion was measured after stimulation with theophylline and prostaglandin E₂.

Results: Neither epithelial resistance nor mannitol fluxes were significantly altered compared with intact controls, indicating no barrier defect in pouchitis. Subepithelial resistances of intact pouches and pouchitis were increased compared with deviation (18.2 (1.6) and 24.3 (1.5) v 13.6 (1.0) Ω×cm²) consistent with an adaptive thickening of the subepithelial layer. In contrast, active Cl⁻ secretion of pouchitis tissues was reduced versus intact pouch and controls (1.4 (0.3) v 4.3 (0.7) and 4.6 (0.7) μmol/h/cm²), and Na⁺-glucose cotransport of pouchitis was reduced compared with intact pouch and controls (1.8 (0.5) v 4.2 (0.8) and 8.8 (1.3) μmol/h/cm²).

Conclusions: Ileal mucosa in pouchitis and terminal ileum prior to IPAA exhibit impaired secretory and absorptive transport functions whereas the epithelial barrier function remains unchanged. This differs from findings in ulcerative colitis. Thus the hypothesis that pouchitis represents a remanifestation of ulcerative colitis has to be questioned.