title: Incrimination of anaerobic bacteria in the induction of experimental colitis.
abstract: Commensal bacteria may participate in the pathogenesis of bowel inflammation. We studied the role of bacteria from the rat colonic flora on transmural inflammation induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). First, bacterial translocation to the colonic wall after induction of colitis was assessed by microbiological and histological methods. Second, rats with a colonic segment excluded from fecal transit were prepared for recolonization with preselected bacteria and used to test the effects of different species on inflammation (eicosanoid release, tissue myeloperoxidase) and damage (histology). Six strains (three aerobes and three anaerobes) were identified in colonic tissue 24 h after induction of colitis. Acridine staining showed bacteria in necrotic areas of the mucosa and invading the submucosa. Rats with excluded colon and sterile culture of luminal washings showed mild inflammation and low mucosal damage in response to TNBS. Rats colonized with anaerobes showed significantly higher eicosanoid release than rats colonized with aerobes only. Moreover, submucosal-lesions were mostly observed in rats with anaerobes. Our findings suggest that colonic anaerobes play a key role in transmural inflammation.
authors.affiliation: Digestive System Research Unit, Hospital General Vall d'Hebron, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: García-Lafuente
authors.forename: M
authors.initials: M
authors.lastname: Antolín
authors.forename: F
authors.initials: F
authors.lastname: Guarner
authors.forename: E
authors.initials: E
authors.lastname: Crespo
authors.forename: A
authors.initials: A
authors.lastname: Salas
authors.forename: P
authors.initials: P
authors.lastname: Forcada
authors.forename: M
authors.initials: M
authors.lastname: Laguarda
authors.forename: J
authors.initials: J
authors.lastname: Gavaldá
authors.forename: J A
authors.initials: JA
authors.lastname: Baena
authors.forename: J
authors.initials: J
authors.lastname: Vilaseca
authors.forename: J R
authors.initials: JR
authors.lastname: Malagelada
mesh_terms: D000818:Animals; D001421:Bacteria, Anaerobic; D001424:Bacterial Infections; D003092:Colitis / Q000139:chemically induced / Q000378:metabolism / Q000382:microbiology*; D003106:Colon / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D015232:Dinoprostone / Q000378:metabolism; D000431:Ethanol; D008297:Male; D009336:Necrosis; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014302:Trinitrobenzenesulfonic Acid
chemical_list: D000431:Ethanol; D014302:Trinitrobenzenesulfonic Acid; D009195:Peroxidase; D015232:Dinoprostone