The role of infection in the aetiology of inflammatory bowel disease

Abstract

We have greatly increased our understanding of the genetics of inflammatory bowel disease (IBD) in the last decade; however, migrant studies highlight the importance of environment in disease risk. The possibility that IBD is an infection has been debated since the first description of Crohn's disease. Mycobacterium avium paratuberculosis was the first organism to be suggested as an IBD pathogen, and it has been argued that it fulfils Koch's postulates and could be designated the cause of Crohn's disease. Other organisms have been postulated as possible IBD pathogens, including various Helicobacter species, one of which has been identified in primate colitis;others are widely used in animal models of IBD. Adherent invasive Escherichia coli appear specific to ileal Crohn's disease and have been shown to induce the release of TNF-alpha, a key cytokine in IBD inflammation. The aim of this article is to give a concise overview of the infections postulated as being relevant to the onset of IBD. We will also briefly cover the immunology underpinning IBD, in addition to reviewing current knowledge regarding other microorganisms that are associated with modifying the risk of developing IBD. It may be that infectious organisms have an orchestrator role in the development of dysbiosis and subsequently IBD.

Pathogenesis of Crohn’s disease: Bug or no bug

“…Dietary alterations in the Western populations have resulted in a shift in the composite gut microbiota. Colonic bacteria have a metabolic function, with a symbiotic relationship with human beings [4] .…”

“…Gut microbiota, which outnumber human cells by nearly ten-fold and contain more than one million genes [4,5] , have been shown to play an important role in complex disorders such as IBD. Historical animal models of CD initiated granulomatous change in both mice and rabbits by infiltrating healthy animal tissue with human Crohn's tissue [6][7][8] .…”

Proper use of Quinolones for canine colitis ambulatory treatment: literature review and REQUEST guidelines

“…An infectious agent responsive to FQ therapy plays an integral role in the clinical manifestation of canine colitis, especially HUC and supports the use of FQ (Hansen et al 2010). Although the correlation between clinical remission and eradication of mucousally invasive E. coli during the treatment with enrofloxacine supports the causal involvement of E. coli in the development of HUC in susceptible Boxer dogs, the poor response to enrofloxacin treatment in granulomatous colitis might be due to colonisation with enrofloxacin-resistant E. coli (Mansfielt et al 2009).…”

“…Several investigations showed that E. coli as a pathogen in inflammatory bowel disease (IBD) has invasive and adherent properties in humans and similar organisms have also been found to be universally present in the granuloma tissue from Boxer dogs with colitis (Simpson et al 2006, Hansen et al 2010) especially histiocytic ulcerative colitis. However, although HUC displays a higher predisposition in Boxers (Hill and Sulivan 1978, German et al 2000, Davies et al 2004, Mansfielt et al 2009) it has also been described in other breeds, such as French buldog, Doberman pincher, Mastiff and Alaskan malamute (Stokes et al 2001, Tanaka et al 2003, Hostutler et al 2004, Cerquetella et al 2010).…”

“…The results of the literature review and classification according the Request scale (Table 1) concerning canine colitis revealed that FQ may be used in these cases that are caused by infectious agent especially E. coli (Cummings et al 2003, Balfour Satrtor 2008, Hansen et al 2010.…”