Evaluation of SAP Expression in Experimental Model of Denture Stomatitis

The presence of fungus Candida albicans in the microbial biofilm adherent underlying removable dental prostheses is related to an inflammatory reaction of the alveolar mucosa, known as denture stomatitis (DS). C. albicans is known to produce secreted aspartyl proteinases (SAPs) to aid adhesion, invasion and tissue destruction. Studies involving the biofilm process on dentures correlated to SAPs expression have primarily been limited to in vitro models.  Objective:  Development of an in vivo experimental model for Candida-associated DS which allows the analyses of SAP2, SAP5 and SAP9 gene expression from C. albicans biofilm-induced on denture surface in contact with palatal mucosa of rats, as well to correlate those expressions with rats` leukocyte count, clinical and histological palatal changes. Method: Thirty five male Wistar were divided into three groups: Control, Denture and Denture/Candida group. The last two groups remained with dentures for 2, 4 and 6 days, with or without induced biofilm. SAP-2, -5 and -9 gene expression was analysed by real time RT-PCR, histologic evaluation by HE and PAS stain and peripheral blood was sent to a veterinary lab for leukocyte count.  Two observers analyzed the palate of the rats for clincal evaluation. Result: On the 4^th day, the Denture/Candida group best mimicked the Candida-associated DS, showing a significant increase of neutrophils in the peripheral blood, presence of inflammation signs on the palate similar to DS Newton type I, and fungal invasion in epithelial layer. In accordance, on the 4^th day, the Denture/Candida group presented the highest relative expression of all studied SAPs. Conclusion: The results showed a concordance of SAPs gene expression with clinical, microscopic and blood results. The molecular findings were consistent with the virulence capacities of C. albicans, present in the biofilm on the denture resin, which allowed fungal invasion into the epithelial tissue.