Adherence of yeast and filamentous forms of Candida albicans to cultured enterocytes.
OBJECTIVE
Systemic candidiasis is a major cause of complicating infections in intensive care units. Morbidity and mortality are high, even in those who receive appropriate antifungal therapy. Because the intestinal tract is considered a major portal of entry for systemic candidiasis, experiments were designed to clarify the ability of yeast and filamentous forms, as well as the INT1 gene product, to influence adherence of Candida albicans to the intestinal epithelium.


METHODS
Controlled.


METHODS
University teaching hospital research laboratory.


METHODS
Mature Caco-2 and HT-29 cultured enterocytes.


METHODS
C. albicans INT1 mutant strains, defective in filament production, were used to observe the ultrastructural surface interactions of C. albicans with cultured intestinal epithelial cells, namely Caco-2 and HT-29 cells. These mutant strains also were used to quantify the effect of the INT1 gene product on C. albicans adherence (yeast and filamentous forms) to cultured enterocytes. Ultrastructural surface interactions of C. albicans with cultured enterocytes were observed with high resolution scanning electron microscopy. C. albicans adherence to cultured enterocytes was quantified by using a colorimetric enzyme-linked immunosorbent assay.


RESULTS
Both yeast and filamentous forms of C. albicans appeared tightly adherent to the apical surface of cultured enterocytes, and INT1 appeared to have little, if any, effect on these ultrastructural surface interactions. The distal ends of C. albicans filaments appeared to mediate adherence to enterocyte apical microvilli, and thigmotropism (contact guidance) appeared to play a role in C. albicans adherence. The absence of functional INT1 was associated with decreased adherence of C. albicans yeast forms to cultured enterocytes.


CONCLUSIONS
Although functional INT1 appeared to facilitate adherence of C. albicans yeast forms to cultured enterocytes, the role of INT1 in adherence of filamentous forms was unclear, and both yeast and filamentous forms could adhere to, and perhaps invade, the apical surface of cultured enterocytes.
Wiesner
Stephen M
SM
Department of Laboratory Medicine & Pathology, University of Minnesota, Minneapolis 55455-0374, USA.
Bendel
Catherine M
CM
Hess
Donavon J
DJ
Erlandsen
Stanley L
SL
Wells
Carol L
CL
D018938:Caco-2 Cells / Q000382:microbiology* / Q000648:ultrastructure; D002176:Candida albicans / Q000472:pathogenicity* / Q000648:ultrastructure; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000502:physiology; D020895:Enterocytes / Q000382:microbiology* / Q000648:ultrastructure; D005656:Fungal Proteins; D019073:HT29 Cells / Q000382:microbiology* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning
D015815:Cell Adhesion Molecules; D005656:Fungal Proteins; C097687:alphaINT1 protein, Candida albicans