Mycobacterium aviumsubspeciesparatuberculosisin the etiology of Crohn’s disease, cause or epiphenomenon?

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.

Gut microbiota and IBD: causation or correlation?

“…Mycobacterium avium subsp. paratuberculosis has also been investigated as a potential cause of Crohn's disease owing to its ability to cause chronic granulomatous enteritis in sheep and cattle 41–44 ; however, clinical studies have not borne out this hypothesis 45,46 . Similarly, a specific association between Fusobacterium nucleatum , ulcerative colitis and the development of colorectal cancer has been proposed based on the isolation of a highly invasive strain from patients with ulcerative colitis, but a clear cause-and-effect relationship has not been proven 47,48 .…”

<i>Mycobacterium avium subspecies paratuberculosis</i>: A possible causative agent in human morbidity and risk to public health safety

“…Studies have shown however, that it is extremely difficult to grow MAP from human samples where MAP exists with a modified cell wall making it resistant to standard identity staining techniques (Sechi et al, 2005) couple with specific growth requirements such as certain levels of iron which it sources from its hosts . Additionally, JD does not display some of the manifestations of CD such as the segmental localization and features such as fistula, fissures, bleeding, stenosis, adhesions, perforation and the formation of abscesses (Liverani et al, 2014). In order to prove without a doubt that MAP causes IBD, live organisms must be isolated and cultured from a patient and shown to be able to infect and cause morbidity in a second host.…”

The role of IL-10 in Mycobacterium avium subsp. paratuberculosis infection

“…In 1913, Dalziel reported the link between MAP and human Morbus Crohn disease (CD). Several studies have demonstrated the presence of MAP in CD cases, but the causative role of MAP in CD is not established yet [11, 12]. Similarly McNees and colleagues reported that MAP can be cultured from mononuclear cells of Crohn’s disease patient’s but it does not establish the etiology [13].…”