Enhanced Escherichia coli adherence and invasion in Crohn's disease and colon cancer

Altered mucosal glycosylation in inflammatory bowel disease and colon cancer could affect mucosal bacterial adherence. This study aimed to quantify and characterize mucosa-associated and intramucosal bacteria, particularly Escherichia coli, in these conditions.

Mucosa-associated bacteria were isolated, after dithiothreitol mucolysis, from biopsy samples obtained at colonoscopy (Crohn's disease, n = 14 patients; ulcerative colitis, n = 21; noninflamed controls, n = 24) and at surgical resection (colon cancer, n = 21). Intramucosal bacteria were grown after gentamicin treatment followed by hypotonic lysis.

Mucosa-associated and intramucosal bacteria were cultured more commonly in Crohn's disease (79%, P = 0.03; and 71%, P < 0.01, respectively), but not ulcerative colitis (38% and 48%), than in noninflamed controls (42% and 29%) and were commonly cultured from colon cancers (71% and 57%). Mucosa-associated E. coli, which accounted for 53% of isolates, were more common in Crohn's disease (6/14; 43%) than in noninflamed controls (4/24, 17%), as also were 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 (P = 0.01) with adherence to the I407 and HT29 cell lines. Invasion was cell-line dependent. E. coli, including nonadherent 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.

These studies support a central role for mucosally adherent bacteria in the pathogenesis of Crohn's disease and colon cancer. Soluble plant fibers that inhibit their adherence have therapeutic potential.