Mucin expression in the ileoanal reservoir reflects incomplete mucosal adaptation

Abstract

Restorative proctocolectomy is regarded as a standard surgical procedure for patients who require a proctocolectomy for ulcerative colitis and familial adenomatous polyposis. The ileal mucosa undergoes colonic phenotypic change with time, but the extent and relevance of these changes to the long-term safety of the ileoanal pouch are unclear. The aim of this study was to study the mucin biology of this adaptive process in order to assess its extent and possible impact on pouch safety. Ileoanal pouch biopsies from a cohort of patients and normal ileal and colonic controls were subjected to histological, biochemical, histochemical, and immunohistochemical mucin analysis. Mucin sulphation and sialic acid O-acetylation were studied as parameters of colonic phenotypic change. Fifty-one patients, 16 ileal, and 22 colonic controls were studied. Seventy per cent of biopsies retained villous mucosal architecture, with no cases of dysplasia detected. Ileoanal pouch mucosal sulphation and sialic acid O-acetylation did not reach colonic levels, thus indicating limited evidence for a more colonic phenotype. The data from this study suggest that colonic phenotypic change within the ileoanal reservoir is incomplete, with no cases of dysplasia detected. The degree of phenotypic change is less than in previous studies, which may support, but not prove, our hypothesis that there may be a process of reversion to an ileal type mucosa in the ileoanal reservoir with time.

Prophylactic Surgery for Patients with Longstanding Ulcerative Colitis. Which Option? Histopathological and Clinical Implications

“…Usually this is not a fully developed colonic pattern but more of a complete type with a mixture of neutral, sialomucins and a variable amount of sulphated mucins. This transition is considered a marker for malignancy transformation on a molecular level, but far from all with these changes develop carcinoma [27,28]. In most reports this mucinous transformation is not a common feature and when found is usually of incomplete type.…”

Mucin gene expression in the ileoanal reservoir is altered and may be relevant to the risk of inflammation and dysplasia

“…This modification towards a colonic phenotype occurs within the first 9-12 months after IAR construction 8 but studies of older pouches indicate a predominantly ileal phenotype. 9 The risk of neoplasia with increased age of IARs remains a concern although there is little clear evidence that this risk is significant. Two long term studies of morphological changes in the IAR 10 11 suggest that two groups can be identified.…”

Systematic review of dysplasia after restorative proctocolectomy for ulcerative colitis

“…A further 24 of the remaining 47 papers were excluded, of which 12 did not include an evaluation of dysplasia in either the methods or results section6, 38–49, ten duplicated published data49–58 and two failed to meet the quality standard59, 60. The 23 studies included in the analysis are listed in Table 3 5, 35, 61–81. Only uncontrolled observational studies were identified, of which six were prospective and 17 were retrospective case series, all published between 1994 and 2005.…”

“…Characteristics of patients in each study are described in Table 3 . Biopsies were taken from the pouch mucosa in 14 studies5, 61, 64, 66–68, 70, 72, 73, 76–78, 80, 81. The rectal cuff and the anal transitional zone were examined in three studies35, 65, 74 and in six studies biopsies were taken from both sites62, 63, 69, 71, 75, 79.…”