Topic Highlight
Copyright ©2007 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 14, 2007; 13(42): 5571-5576
Published online Nov 14, 2007. doi: 10.3748/wjg.v13.i42.5571
Role of bacteria in the etiopathogenesis of inflammatory bowel disease
Nicolas Barnich, Arlette Darfeuille-Michaud
Nicolas Barnich, Arlette Darfeuille-Michaud, Pathogénie Bactérienne Intestinale, Univ Clermont 1, USC INRA 2018, Clermont-Ferrand F-63001 and Institut Universitaire de Technologie en Génie Biologique, Aubière F-63172, France
Author contributions: All authors contributed equally to the work.
Supported by grants from Ministère de la Recherche et de la Technologie (EA3844) and INRA (USC 2018), Association F Aupetit, Institut de Recherche des Maladies de l'Appareil Digestif, laboratoire Astra France
Correspondence to: Nicolas Barnich, PhD, Pathogénie Bactérienne Intestinale, USC INRA 2018, Université d'Auvergne, Centre Biomédical de Recherche et Valorisation, 28 Place Henri Dunant, Clermont-Ferrand 63000, France. nicolas.barnich@u-clermont1.fr
Telephone: +33-4-73177997 Fax: +33-4-73178371
Received: June 22, 2007
Revised: August 28, 2007
Accepted: September 4, 2007
Published online: November 14, 2007
Abstract

Increased numbers of mucosa-associated Escherichia coli are observed in both of the major inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis (UC). A potential pathophysiological link between the presence of pathogenic invasive bacteria and genetic host susceptibility of patients with ileal CD is suspected. In CD patients, with increased ileal expression of the CEACAM6 molecule acting as a receptor recognized by type 1 pilus bacterial adhesin, and with the identification of mutations in the NOD2-encoding gene, the presence of pathogenic invasive bacteria could be the link between abnormal ileal bacterial colonization and innate immune responses to invasive bacteria. In a susceptible host, the sequential etiological steps of the disease induced by adherent-invasive E. coli (AIEC) are: (1) abnormal colonization via binding to the CEACAM6 receptor, which is overexpressed in the ileal mucosa of CD patients; (2) ability to adhere to and to invade intestinal epithelial cells, which allows bacteria to cross the mucosal barrier; (3) survival and replication within infected macrophages in the lamina propria; and (4) induction of tumor necrosis factor-α secretion and granuloma formation.

Keywords: Adherent-invasive Escherichia coli; Crohn's disease; Inflammatory bowel disease; Ulcerative colitis