Binding of Clostridium difficile to Caco-2 epithelial cell line and to extracellular matrix proteins.

Adhesion of Clostridium difficile to Caco-2 was examined as a function of monolayers polarization and differentiation. The number of adherent C. difficile C253 bacteria per cell strongly decreased when postconfluent 15-day-old monolayers were used (1.7 bacteria per cell versus 17.3 with 3-day-old monolayers). Following disruption of intercellular junctions by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N',-tetraacetic acid, a significant rise in the level of bacterial adhesion was observed, above all in postconfluent monolayers. Immunofluorescence studies of bacteria and transferrin receptor, a marker of basolateral pole of polarized monolayers, showed that C. difficile C253 adheres mainly to the basolateral surface of differentiated and undifferentiated polarized Caco-2 cells. Furthermore, binding of C. difficile C253 to several extracellular matrix proteins in vitro was demonstrated by an ELISA-based assay.