Adherent-invasive Escherichia coli (AIEC) pathovar has been identified in the intestinal mucosa of patients with Crohn’s disease.
The adherent-invasive E. coli reference strain LF82 is able to adhere to intestinal epithelial cells. It can also invade epithelial cells via a mechanism involving actin polymerization and microtubules, and to survive and replicate within macrophages.
In this study, researchers from France and Germany assessed the prevalence of the adherent-invasive E. coli in Crohn’s and ulcerative colitis patients, as well as controls.
|Adherent-invasive E. coli strains were found in ileal samples of 22% of Crohn’s chronic lesions.|
The team performed a search for E. coli strains using ileal specimens of 63 Crohn’s patients and 16 controls. They also searched colonic specimens of 27 patients with Crohn’s disease, 8 patients with ulcerative colitis, and 102 controls.
The researchers assessed the abilities of the E. coli strains to invade epithelial cells, and to survive and replicate within macrophages.
Bacterial uptake by epithelial cells was analyzed using cytoskeletal inhibitors, and adhesion was quantified with Caco-2 and Intestine-407 cells.
In addition, the team assessed the presence of known E. coli virulence genes using PCR and DNA hybridization.
The team found adherent-invasive E. coli strains in 22% of Crohn’s disease chronic lesions, compared to 6% of the controls, for the ileal samples.
In neoterminal ileal specimens, they found adherent-invasive E. coli strains in 36% of Crohn’s disease early lesions and 22% of healthy mucosa of Crohn’s disease patients.
However, in the colonic specimens, adherent-invasive E. coli strains were found in 4% of Crohn’s disease patients, 0% of ulcerative colitis patients, and 2% of controls.
Dr Arlette Darfeuille-Michaud and colleagues concluded, " Adherent-invasive E. coli strains are associated specifically with ileal mucosa in Crohn’s disease".