Infection of HEp2 epithelial cells with Candida albicans: adherence and postadherence events

We have previously observed that the infection of HEp2 epithelial cells with Candida albicans results in HEp2 cell actin rearrangement, and that a culture filtrate of C. albicans (Candida metabolite) caused the same changes and reduced membrane ruffling and motility. It was found that the Candida metabolite consisted of several proteins and nonproteinaceous components. In this study we report on the identity of three of the main proteins in the Candida metabolite, namely a secretory aspartate protease (Sap), an agglutinin-like adhesion sequence (Als) and a glucan 1,3-beta-glucosidase. The effect on HEp2 cells caused by the Candida metabolite, an inhibitor of the PKC MAP kinase signal pathway - bisindolylmaleimide (BIM), or the actin polymerization inhibitor - cytochalasin D (CyD) were studied alone and in combination. Exposure of HEp2 cells to the Candida metabolite, together with the BIM or CyD, had profound effects on HEp2 cell morphology, as compared to individually treated cells, and also reduced the adherence of the organisms to HEp2 cells. Our results show that the interaction of C. albicans with HEp2 cells is, not unexpectedly, complex, and involves changes in the host cell that may be related to the effect of Candida-secreted biomolecules.