Mucin changes in ileoanal pouches monitored by metabolic labelling and histochemistry

Abstract

The pattern of mucin synthesis and secretion in mucosal biopsies from the proximal ileum, distal ileum, rectum and pouch before and after ileostomy closure was monitored in patients undergoing restorative proctocolectomy by metabolic labelling with [3H]glucosamine and [35S]sulphate and compared with the mucin histochemistry in each patient. Metabolic labelling clearly demonstrated a reduction in sulphation associated with the rectal mucosa in colitis. Significant differences in the turnover of isolated secreted mucin between proximal and distal ileum and rectum were also found, as was a metaplastic change towards a colonic-type mucosa in the pouch before and after ileostomy closure relative to the proximal and distal ileum, and rectum. This technique can be used to monitor colonic metaplasia in the pouch mucosa and is suitable for comparative studies where mucin changes are implicated.

Prevalence of Adenomas and Carcinomas in the Ileal Pouch After Proctocolectomy in Patients with Familial Adenomatous Polyposis

“…When fecal stasis occurs such as in a reconstructed pouch, the incidence of neoplasia in ileal mucosa may increase. Several authors have implicated colonic metaplasia as the reason for the development of ileal adenomas 8,19,20 and even carcinomas in the pouch of patients with FAP. [21][22][23] Colonic metaplasia was frequently reported in the earlier descriptions of changes observed in the ileal pouch mucosa, and some considered it an adaptive Values are mean ± SD unless otherwise noted Kock Kock's continent ileostomy, IRA ileorectal anastomosis, IPAA ileal pouch-anal anastomosis, FAP familial adenomatous polyposis response of the pouch to its role as a neorectum.…”

Altered mucin expression in the gastrointestinal tract: a review

“…Within a year of the procedure there is a switch from a small intestinal to a colonic mucin pattern. The principal change is to the carbohydrate component as evidenced by increased sulphation and O-acetylation [55,56]. Pouchitis, which occurs mainly in subjects with ulcerative colitis, has been viewed as a return of the disease in a segment of ileum that has undergone an adaptive 'colonisation'.…”

Sulfate-Reducing Bacteria Colonize Pouches Formed for Ulcerative Colitis but Not for Familial Adenomatous Polyposis

“…Increased villous atrophy and crypt cell hyperplasia are characteristic features of both active colitis and pouchitis. 30 SRB require sulfur for growth and other activities. Sources of dietary sulfur include sulfated mucopolysaccharides.…”

“…28 The mucous gel layer is an additional source because in ileal pouches and colon, there is a predominance of colonic type mucin (high in sulfates) compared with small bowel type mucin (high degree of sialylation). 30,31 The utilization of the mucous barrier as an energy source may lead to depletion and increased epithelial exposure to luminal contents.…”