Substance P- and vasoactive intestinal polypeptide-immunoreactive innervation in normal and inflamed pouches after restorative proctocolectomy for ulcerative colitis

Recent studies suggest that the intestinal polypeptides substance P (SP) and vasoactive intestinal polypeptide (VIP) play a role in the bowel inflammatory processes. The aim of this study was to evaluate the distribution of SP and VIP immunoreactivities in the ileal pouch of the patients with ulcerative colitis (UC). Thirty-six patients underwent clinical evaluation, endoscopy, and histological examinations. Samples were taken from normal ileum (N=9), ileum of UC patients (N=9), normal ileal pouch (N=9), and pouchitis (N=9). SP- and VIP-containing nerve fibers were visualized in sections processed for immunofluorescence microscopy. The number and intensity of SP and VIP immunoreactivities were subjected to quantitative scoring. On samples from all groups lamina propria contained fibers showing bright immunofluorescence for SP and VIP. The number and intensity of SP immunoreactive nerve fibers were markedly increased in pouchitis as compared to normal pouch (P<0.005), to ileum of UC patients (P<0.001), and to normal ileum (P<0.05). The number and intensity of VIP-immunoreactive nerve fibers in the lamina propria were markedly increased in pouchitis patients and in those having a normal pouch as compared to pooled values of ileum of UC patients and normal ileum (P<0.05). The results suggest that SP, which may play a role in mediating inflammatory processes, is increased in pouchitis and that VIP, which may contribute to the regulation of intestinal motility, is increased in the pouch.