Structural and functional lesions in brush border of human polarized intestinal Caco-2/TC7 cells infected by members of the Afa/Dr diffusely adheringfamily of Escherichia coli

Diffusely adhering Escherichia coli (DAEC) strains expressing F1845 fimbria l adhesin or Dr hemagglutinin belonging to the Afa/Dr family of adhesins in fect cultured polarized human intestinal cells through recognition of the b rush border-associated decay-accelerating factor (DAF; CD55) as a receptor. The wild-type Afa/Dr DAEC strain C1845 has been shown to induce brush bord er lesions by an adhesin-dependent mechanism triggering apical F-actin rear rangements. In the present study, we undertook to further characterize cell injuries following the interaction of wild-type Afa/Dr DAEC strains C1845 and IH11128 expressing fimbrial F1845 adhesin and Dr hemagglutinin, respect ively, with polarized, fully differentiated Caco-2/TC7 cells. In both cases , bacterium-cell interaction was followed by rearrangement of the major bru sh border-associated cytoskeletal proteins F-actin, villin, and fimbrin, pr oteins which play a pivotal role in brush border assembly. In contrast, dis tribution of G-actin, actin-depolymerizing factor, and tubulin was not modi fied. Using draE mutants, we found that a mutant in which cysteine replaces aspartic acid at position 54 conserved binding capacity but failed to indu ce F-actin disassembly, Accompanying the cytoskeleton injuries, we found th at the distribution of brush border-associated functional proteins sucrase- isomaltase (SI), dipeptidylpeptidase IV (DPPIV), glucose transporter SGLT1, and fructose transporter GLUTS was dramatically altered. In parallel, SI a nd DPPIV enzyme activity decreased.