Increased immunoendocrine cells in intestinal mucosa of postinfectious irritable bowel syndrome patients 3 years after acute Shigella infection--an observation in a small case control study

Abstract

Purpose: Postinfectiously irritable bowel syndrome (PI-IBS) develops in 3-30% of individuals with bacterial gastroenteritis. Recent studies demonstrated increases in inflammatory components in gut mucosa of PI-IBS patients even after complete resolution of infection. We aimed to investigate histological changes in colon and rectum of PI-IBS subjects after long term period of infection.

Materials and methods: We recruited PI-IBS subjects who had been diagnosed IBS after complete resolution of enteritis caused by shigellosis outbreak 3 years earlier. We compared unmatched four groups, PI-IBS (n = 4), non PI-IBS (n = 7), D-IBS (n = 7, diarrhea predominant type) and healthy controls (n = 10). All of them underwent colonoscopic biopsy at three areas, including descending colon (DC), sigmoid colon (SC) and rectum, which were assessed for 5-hydroxytryptamine (5-HT)/peptide YY (PYY)-containing enterochromaffin (EC) cell, intraepithelial (IEL) and lamina propria T lymphocyte (CD3), CD8 lymphocytes, mast cells and CD68/calprotectin+ macrophages.

Results: All subjects had no structural or gross abnormalities at colonoscopy. In PI-IBS, 5-HT containing EC cells, PYY containing EC cells, IELs, CD3 lymphocytes, CD8 lymphocytes, mast cells, and CD68 + macrophages were increased compared to control (p < 0.05). In D-IBS, PYY containing EC cells, IELs, and CD3 lymphocytes were increased compared to control (p < 0.05). In PI-IBS, 5-HT containing EC cells tended to increase and PYY containing EC cells, CD8 lymphocytes, mast cells, and CD68+ macrophages were increased compared to non PI-IBS (p < 0.05). Calprotectin + marcrophages were decreased in PI-IBS, non PI-IBS and IBS compared to control.

Conclusion: The immunoendocrine cells were sporadically increased in PI-IBS, non PI-IBS and D-IBS compared with control. Our findings in a very small number of patients suggest that mucosal inflammation may play a role in long-term PI-IBS, and that other sub-groups of IBS and larger scale studies are needed to confirm this observation.

Keywords: Post infectious irritable bowel syndrome; T lymphocyte; enterochromaffin cell; macrophage; mast cell.

Fig. 1

Differences of counts of cellular markers between PI-IBS and controls. There were significant increase of all mucosal markers and decrease of calprotectin positive cells in patients with PI-IBS, compared to control. PI-IBS, postinfectious irritable bowel syndrome; IEL, intraepithelial. ^*p< 0.05, Cell counts/100 epithelial cells for 5-HT, IEL. Cell counts/160,000 µm² for peptide YY, CD3, mast cell, CD68, calprotectin.

Fig. 2

Differences of counts of cellular markers between PI-IBS and non PI-IBS. EC cells stained for PYY, CD8 positive lymphocytes, mast cells and CD68 positive macrophages were increased in PI-IBS patients, compared to non PI-IBS group. 5-HT positive EC cells showed increased tendency in PI-IBS group compared to non PI-IBS group. (p = 0.085 in DC, p = 0.058 in rectum). PI-IBS, postinfectious irritable bowel syndrome; PPY, peptide YY; IEL, intraepithelial. ^*p< 0.05. Cell counts/100 epithelial cells for 5-HT, IEL. Cell counts/160000 µm² for PYY, CD3, mast cell, CD68, calprotectin.