Review
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World J Gastroenterol. Sep 28, 2014; 20(36): 13060-13070
Published online Sep 28, 2014. doi: 10.3748/wjg.v20.i36.13060
Mycobacterium avium subspecies paratuberculosis in the etiology of Crohn’s disease, cause or epiphenomenon?
Elisa Liverani, Eleonora Scaioli, Carla Cardamone, Paola Dal Monte, Andrea Belluzzi
Elisa Liverani, Eleonora Scaioli, Carla Cardamone, Andrea Belluzzi, Gastroenterology Division, Department of Medical and Surgical Sciences, Sant’Orsola-Malpighi University Hospital, 40138 Bologna, Italy
Paola Dal Monte, Diagnostic and Speciality Medicine, Department of Experimental, Microbiology Unit, Sant’Orsola-Malpighi University Hospital, 40138 Bologna, Italy
Author contributions: Liverani E, Scaioli E, Cardamone C and Belluzzi A contributed equally to this work; Liverani E and Belluzzi A conceived and designed the manuscript; Dal Monte P analyzed the data; Scaioli E and Cardamone C wrote the paper.
Correspondence to: Andrea Belluzzi, MD, Gastroenterology Division, Department of Medical and Surgical Sciences, Sant’Orsola-Malpighi University Hospital, via Massarenti 9, 40138 Bologna, Italy. andrea.belluzzi@aosp.bo.it
Telephone: +39-051-6363873 Fax: +39-051-6363873
Received: January 20, 2014
Revised: April 30, 2014
Accepted: May 25, 2014
Published online: September 28, 2014
Processing time: 253 Days and 21.7 Hours
Abstract

The origin of inflammatory bowel disease is unknown. Attempts have been made to isolate a microorganism that could explain the onset of inflammation, but no pathological agent has ever been identified. Johne’s disease is a granulomatous chronic enteritis of cattle and sheep caused by Mycobacterium avium subspecies paratuberculosis (MAP) and shows some analogies with Crohn’s disease (CD). Several studies have tried to clarify if MAP has a role in the etiology of CD. The present article provides an overview of the evidence in favor and against the “MAP-hypothesis”, analyzing the methods commonly adopted to detect MAP and the role of antimycobacterial therapy in patients with inflammatory bowel disease. Studies were identified through the electronic database, MEDLINE, and were selected based on their relevance to the objective of the review. The presence of MAP was investigated using multiple diagnostic methods for MAP detection and in different tissue samples from patients affected by CD or ulcerative colitis and in healthy controls. On the basis of their studies, several authors support a close relationship between MAP and CD. Although increasing evidence of MAP detection in CD patients is unquestionable, a clear etiological link still needs to be proven.

Keywords: Mycobacterium avium paratuberculosis; Crohn’s disease; Inflammatory bowel disease; Johne’s disease; Mycobacterial protein tyrosine phosphatase

Core tip: The etiology of inflammatory bowel disease (IBD) is unknown. Some analogies between Crohn’s disease (CD) and Johne’s disease, a granulomatous chronic enteritis of cattle and sheep caused by Mycobacterium avium subspecies paratuberculosis (MAP) have been identified. Several studies have tried to clarify if MAP has a role in the etiology of CD. However, the involvement of MAP in CD is still debatable. The present article provides a literature review of the evidence in favor and against the “MAP-hypothesis”, the methods commonly adopted to detect MAP and the role of antimycobacterial therapy in treating IBD patients. In particular, new mechanistic findings seem to encourage the CD-MAP relationship.