HIV protease inhibitor: an antifungal agent?

Abstract

BACKGROUND: Protease inhibitors were shown to inhibit Candida albicans adherence to epithelial cells but not endothelial cells. Whether protease inhibitors have any effect on C. albicans adherence to acrylic surface and can be used as an antifungal is still unknown. Aims: The current study aimed to investigate whether protease inhibitors attenuate Candida albicans adherence to acrylic surface. The effect of three protease inhibitors, namely Saquinavir, Ritonavir and Indinavir on adherence were compared. METHODS: C. albicans suspensions were pre-treated with different concentrations (0.8, 4, 20, 100 and 500 μM) of Saquinavir, Ritonavir or Indinavir for one hour. The yeast cells were then allowed to adhere on acrylic strips treated with human pooled saliva for another hour (Group A). Adherence was determined by calculating the percentage of cell area over the acrylic surface using an image analyser. Another group with C. albicans not pre-treated with protease inhibitors (Group B) and a control group with no protease inhibitors added (Group C) were also included. RESULTS: All three protease inhibitors significantly attenuated adherence of C. albicans to acrylic surface. Group B showed significant reduction in adhesion compared with Group C. 50% reduction in adherence occurred at concentrations of 100 μM, 100 μM and 20 μM, for Saquinavir, Ritonavir and Indinavir, respectively. A dose dependent inhibition of adhesion were observed for all the protease inhibitors in Group A, which was significantly higher in Indinvavir than in Saquinavir and Ritonavir. However, such difference disappeared at concentration of 500 μM. CONCLUSIONS: Protease inhibitor had a direct effect on C. albicans pathogenicity; it attenuated C. albicans adherence to acrylic surfaces in a dose related fashion. Moreover, different protease inhibitors exhibited different degrees of inhibition.