Inflammatory bowel disease and colon cancer is associated with altered mucosal glycosylation and it has been postulated that this could affect mucosal bacterial adhesion.
Therefore scientists from the University of Liverpool and the University of Southampton, UK, have aimed to characterize mucosa-associated and intramucosal bacteria, in particular Escherichia Coli.
Helen M Martin and colleagues isolated mucosa-associated bacteria, after dithiothreitol mucolysis from biopsy samples.
A total of 59 biopsy samples were obtained at colonoscopy from patients with either Crohn's disease (n = 14), ulcerative colitis (n = 21) or non-inflamed controls (n = 24).
A further 21 biopsy samples were collected at surgical resection from patients with colon cancer.
|Presence of mucosa-associated E.coli:|
Crohn's disease samples - 43%Non-inflamed controls – 17%
As well as mucosa-associated bacteria, intramucosal bacteria were grown after gentamicin treatment followed by hypotonic lysis.
Both mucosa-associated and intramucosal bacteria were cultured more commonly in Crohn's disease samples (79% and 71% respectively) than in non-inflamed controls (42% and 29% respectively).
However, this was not the case with ulcerative colitis, where mucosa-associated and intramucosal bacteria were only cultured in 38% and 48% of samples, respectively.
Both bacteria were commonly cultured from colon cancers (71% and 57% respectively).
Mucosa-associated E. coli, which accounted for 53% of isolates, were more common in Crohn’s disease (6 of 14; 43%) than in non-inflamed controls (4 of 24, 17%).
The same was also true for intramucosal E. coli (Crohn’s disease, 29%; controls, 9%).
E. coli expressed hemagglutinins in 39% of Crohn’s cases and 38% of cancers but only 4% of controls, and this correlated with adherence to the I407 and HT29 cell lines, with invasion being cell-line dependent.
E. coli, including non-adherent isolates, induced interleukin-8 release from the cell lines. E. coli adhesins showed no blood group specificity, excepting 1 cancer isolate (HM44) with specificity for the Thomsen-Friedenreich antigen, but they could be blocked by soluble plantain fiber.
Commenting on their findings, the authors said, "These studies support a central role for mucosally adherent bacteria in the pathogenesis of Crohn’s disease and colon cancer."
They add that soluble plant fibers that inhibit their adherence have therapeutic potential, and hope to continue this work further, with the University of Liverpool having filed a patent application regarding the use of soluble plantain fiber in Crohn's disease, as a consequence of this work.