Inflammation in irritable bowel syndrome: Myth or new treatment target?

Abstract

Low-grade intestinal inflammation plays a key role in the pathophysiology of irritable bowel syndrome (IBS), and this role is likely to be multifactorial. The aim of this review was to summarize the evidence on the spectrum of mucosal inflammation in IBS, highlighting the relationship of this inflammation to the pathophysiology of IBS and its connection to clinical practice. We carried out a bibliographic search in Medline and the Cochrane Library for the period of January 1966 to December 2014, focusing on publications describing an interaction between inflammation and IBS. Several evidences demonstrate microscopic and molecular abnormalities in IBS patients. Understanding the mechanisms underlying low-grade inflammation in IBS may help to design clinical trials to test the efficacy and safety of drugs that target this pathophysiologic mechanism.

Keywords: Inflammation; Irritable bowel syndrome; Mast cells; Neuroendocrine cells; Pathology.

Figure 1

Literature findings on the relationship between irritable bowel syndrome and inflammation (n = 305).

Figure 2

Immunohistochemistry for tryptase showing increases in the number of mast cells in the colonic mucosa in inflammatory bowel disease. A: Irritable bowel syndrome patient; B: Control (× 40 magnification). Courtesy of Giancarlo Pompei, personal data.

Figure 3

Immunohistochemistry for CD3 showing increase in the number of intraepithelial T-lymphocytes in the large bowel in inflammatory bowel disease. A: Irritable bowel syndrome patient; B: Normal distribution of T-lymphocytes, which are mainly distributed within the lamina propria of the large bowel of a control patient (× 20 magnification). Courtesy of Giancarlo Pompei, personal data.

Figure 4

Immunohistochemical staining for CD20. An equivalent distribution of B lymphocytes in the lamina propria was seen in the large intestine. A: Patient with irritable bowel syndrome; B: Control patient (× 20 magnification). Courtesy of Giancarlo Pompei, personal data.

Figure 5

Immunohistochemistry for chromogranin A showing increased expression in nerve terminals at the level of the basal membrane in the large intestine in inflammatory bowel disease. A: Irritable bowel syndrome patient; B: Control patient (× 40 magnification). Courtesy of Giancarlo Pompei, personal data.