Introduction: Several studies suggest that Adherent-Invasive Escherichia Coli (AIEC) colonize the ileal mucosa of Crohn's disease (CD) patients. These strain is able to adhere to and invade intestinal epithelial cells, and survive within macrophages, prompting an inflammatory response. The aim of this study was to investigate,by using an organ culture model, the ability of AIEC strain O83:H1 to colonize intestinal epithelial cells of CD patients, inducing chronic inflammation. Methods: An organ culture model conducted with colonic biopsies derived from CD patients was set up to evaluate the ability of AIEC strain 083:H1, compared to a non-pathogenic E. Coli (NP) strain, to upregulate CEACAM 6 (CarcinoEmbryonic Antigen-related Cellular Adhesion Molecule 6), LAMP-1 (Lysosome Associated Membrane Protein 1), ICAM-1 (Intracellular Adhesion Molecule) and HLA-DR antigen expression , by immunohistochemistry, and to induce IFN-g, TNF-a and IL-8 production, by RT-PCR. The staining of epithelial cells that expressed CEACAM6 and LAMP1 as well as the expression of ICAM1 on blood vessels was evaluated in terms of staining intensity. The number of LAMP1 and HLA-DR lamina propria mononuclear cells (LPMNC) was evaluated within a total area of 1 mm2 of lamina propria. Results: Expression of CEACAM6 on intestinal epithelial cells, and the expression of LAMP-1 either on epithelium as well as in the LPMNCs, were significantly increased (P, 0,05) in the biopsies cultured with the AIEC strain O83:H1 compared to the biopsies cultured with non-pathogenic (NP) strain. ICAM-1 and HLA-DR were significantly increased (P, 0,05) on blood vessels and on LPMNCs, respectively, in presence of AIEC strain O83:H1 as compared with NP strain. Moreover we observed a higher level of IFN-g, TNF-a and IL-8 mRNA trascripts in biopsies cultured with AIEC strain 083:H1 than in biopsies cultured with NP strain. Conclusion: Expression of CEACAM6 on intestinal epithelial cells, and the expression of LAMP-1 either on epithelium as well as in the LPMNCs, were significantly increased (P, 0,05) in the biopsies cultured with the AIEC strain O83:H1 compared to the biopsies cultured with non-pathogenic (NP) strain. ICAM-1 and HLA-DR were significantly increased (P, 0,05) on blood vessels and on LPMNCs, respectively, in presence of AIEC strain O83:H1 as compared with NP strain. Moreover we observed a higher level of IFN-g, TNF-a and IL-8 mRNA trascripts in biopsies cultured with AIEC strain 083:H1 than in biopsies cultured with NP strain.
