DIFFERENTIAL EXPRESSION OF SECRETED ASPARTYL PROTEINASES IN A MODEL OF HUMAN ORAL CANDIDOSIS AND IN PATIENT SAMPLES FROM THE ORAL CAVITY

Candida albicans, an opportunistic pathogen in humans, secretes secret ory aspartyl proteinases (Saps), which have been correlated with virul ence. We examined the temporal regulation of the mRNA expression of se ven known members of the SAP gene family by reverse transcription poly merase chain reaction (RT-PCR) in (i) an in vitro model of oral candid osis based an reconstituted human epithelium (RHE); and (ii) clinical samples from patients with oral candidosis. SAP1 and SAP3 transcripts were first detected 42h after inoculation of RHE, while at the same ti me, slight morphological alterations in the epithelium were documented by light microscopy. SAP6 expression occurred 6h later concomitantly with germ tube formation of some infecting Candida cells and severe le sions of the epithelial tissue. SAP2 and SAP8 RT-PCR products were fir st detected 60 h after infection, while SAP4 and SAPS transcripts were never discovered. Thus a temporal progression of SAP expression in th e order SAP1 and SAP3> SAP6> SAP2 and SAP8 was observed at the same ti me as increasing RHE damage occurred. At the protein level, Sap antige n was found within the C. albicans yeast cells and the epithelial cell s by immunoelectron microscopy using an anti-Sap murine monoclonal ant ibody directed against the gene products Sap1-3. Expression of SAP1-3 and 6 was also detected by RT-PCR in samples from patients suffering f rom oral candidosis. Our results suggest that the pathogenesis of expe rimental and clinical oral candidosis is associated with the different ial and temporal regulation of SAP gene expression.