Evaluation of gene expression SAP5, LIP9, and PLB2 of Candida albicans biofilms after photodynamic inactivation.

With the increasing number of strains of Candida ssp. resistant to antifungal agents, the accomplishment of researches that evaluate the effects of new therapeutic methods, like photodynamic inactivation (PDI), becomes important and necessary. Thus, the objective of this study was to verify the effects of the PDI on Candida albicans biofilms, evaluating their effects on the expression of the gene hydrolytic enzymes aspartyl proteinase (SAP5), lipase (LIP9), and phospholipase (PLB2). Clinical strains of C. albicans (n = 9) isolated from patient bearers of the virus HIV and a pattern strain ATCC 18804 were used. The quantification of gene expression was related to the production of hydrolytic enzymes using the quantitative polymerase chain reaction (qPCR) assay. For PDI, we used laser-aluminum-gallium arsenide low power (red visible, 660 nm) as a light source and the methylene blue at 300 μM as a photosensitizer. We assessed two experimental groups for each strain: (a) PDI: sensitization with methylene blue and laser irradiation and (b) control: without sensitization with methylene blue and light absence. The PDI decreased gene expression in 60 % of samples for gene SAP5 and 50 % of the samples decreased expression of LIP9 and PLB2. When we compared the expression profile for of each gene between the treated and control group, a decrease in all gene expression was observed, however no statistically significant difference (Tukey's test/p = 0.12). It could be concluded that PDI (photosensitization with methylene blue followed by low-level laser irradiation) showed a slight reduction on the expression of hydrolytic enzymes of C. albicans, without statistical significance.