Potential role of Candida albicans secreted aspartic protease 9 in serum induced-hyphal formation and interaction with oral epithelial cells.

INTRODUCTION: Candida albicans possesses the ability to switch rapidly between yeast to hyphal forms. Hyphal formation is a remarkable pathogenic characteristic, which allows C. albicans to invade into host cells. OBJECTIVES: This study was to investigate the role of the C. albicans SAP9 gene in hyphal formation and invasion ability. METHODS: The morphology of fungal cells in the hyphal-inducing liquid media (YPD+10% fetal bovine serum) was observed by the microscopy. And the morphology of the colony on solid agar plates of YPD+10% fetal bovine serum was photographed by the digital camera. The mRNA expressions of hypha-associated genes in serum medium were also analyzed by real time PCR. Then for the interaction between C. albicans and oral epithelial cells, endocytosis essay, invasion essay and damage assay were performed to compare the differences between the sap9Δ/Δ mutant strain and wild type strain. RESULTS: Compared with the wild type strain, the sap9Δ/Δ mutant strain exhibited a deficient yeast-to-hyphal morphological transition under serum hyphal-inducing conditions. Furthermore, the SAP9 knockout strain revealed a significant down-regulation of the expression of EFG1 (~40%), which is a transcription factor gene that mediates hyphae formation in C. albicans. Compared with the wild type strain, a 70% reduction in the endocytosis of the sap9Δ/Δ mutant strain by host cells was observed, as well as a 25% attenuation of active penetration and a 40% attenuation of host cell damage (P <0.05). CONCLUSIONS: Our data strongly suggests that C. albicans Sap9 is a potential hyphal-associated factor that responds to serum hyphal-inducing stimuli via a cAMP-protein kinase A pathway mediated by EFG1, and contributes to the process of invasion of Candida into the epithelial cells, leading to host cell damage.

Prevalence of oral mucosal lesions in adults undergoing highly active antiretroviral therapy in Hong Kong.

AIM: Highly active antiretroviral therapy (HAART) has altered the prevalence and incidence of oral mucosal lesions of HIV infection. Recent reports show a variation in the prevalence of oral mucosal lesions in different population groups. Understanding the prevalence of these lesions is of paramount importance in the efficient delivery of dental care to such cohorts. The aim of the present study was to investigate the prevalence of oral mucosal lesions and salivary parameters during HAART in an ethnic Chinese cohort in Hong Kong. METHODS: A cross-sectional estimation of the prevalence of oral mucosal lesions was carried out in 101 HIV-infected ethnic Chinese in Hong Kong using the European Community-Clearinghouse classification. RESULTS: The prevalence of oral mucosal lesions was more common in patients who were classified at baseline as Centers for Disease Control (CDC) C3 category than CDC A2, A3, B2, and B3 (P < 0.05). An overall prevalence of 1.98% was observed for oral Kaposi's sarcoma. Additionally, the HIV group on HAART (0.37 ± 0.23 mL/min) had significantly lower salivary flow rates (P < 0.01) compared with the healthy group (0.49 ± 0.15 mL/min). CONCLUSIONS: Although HAART appears to markedly reduce the prevalence of oral mucosal lesions during the course of HIV disease, regular systematic oral screening is still warranted for such populations for the early diagnosis and management of pathologies, such as Kaposi's sarcoma.