Assessment of the invasive ability expressed by Escherichia coli strains isolated from the lumen and from different intestinal mucosal sites of inflammatory bowel diseases patients

Abstract

Inflammatory bowel diseases (IBD) are clinical manifestations marked by the upsurge of lesions along the gastrointestinal tract which are associated with chronic inflammatory processes. It is assumed that these processes result from the inability of the immune system in properly recognizing bacterial antigens of the resident microbiota. On the other hand, some authors argue that these reactions depend on the active involvement of bacterial species endowed with pathogenicity factors whose persistence on the mucosa must be responsible for the perpetuation and aggravation of the IBD clinical picture. Escherichia coli is one of the species, whose participation in etiology of the IBD has been suspected. In the end of 1990´s, an E. coli strains showing the ability of invading different epithelial cell lines and potentially able to persist inside regional macrophages was identified in the ileum of a Crohn's Disease (clinical variant of IBD) patient, raising the suspicion of its eventual contribution for the maintenance of the inflammatory picture. On the other hand, work carried out in our laboratory, testing E. coli strains isolated from the rectal mucosa of subjects diagnosed with ulcerative colitis (another clinical variant of IBD), did not identify any strain able to invade HEp-2 cells. To investigate an eventual association of the invasive ability expressed by IBD E. coli strains with their mucosal site of origin, the purpose of this project is to determine the ability of strains isolated from feces and biopsies from distinct intestinal sites of IBD patients. (AU)