Cell Survival and Altered Gene Expression Following Photodynamic Inactivation of Paracoccidioides brasiliensis

Abstract

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides brasiliensis. Currently, the treatment approach involves the use of antifungal drugs and requires years of medical therapy, which can induce nephrotoxicity and lead to resistance in yeast strains. Photodynamic inactivation (PDI) is a new therapy capable of killing microorganisms via the combination of a nontoxic dye with visible light to generate toxic reactive oxygen species (ROS). We investigated the phototoxic effect of 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin (TMPyP), a cationic porphyrin, on the survival of P. brasiliensis following exposure to light. Phototoxicity was found to depend on both the fluence and concentration of the photosensitizer (PS). Although the biological effects of PDI are known, the molecular mechanisms underlying the resultant damage to cells are poorly defined. Therefore, we evaluated the molecular response to PDI-induced oxidative stress by gene transcription analysis. We selected genes associated with the high-osmolarity glycerol (HOG)-mitogen-activated protein kinase (MAPK) pathway and antioxidant enzymes. The genes analyzed were all overexpressed after PDI treatment, suggesting that the oxidative stress generated in our experimental conditions induces antioxidant activity. In addition to PDI-induced gene expression, there was high cell mortality, suggesting that the antioxidant response was not sufficient to avoid fungal mortality.

Melanin Protects Paracoccidioides brasiliensis from the Effects of Antimicrobial Photodynamic Inhibition and Antifungal Drugs

“…yeast cells, corroborating the study of Almeida et al (23). The analysis of ROS and RNS generated after aPI reinforces the statement that, independent of the microorganism, photodynamic inhibition reduces cell viability in a nonspecific way, decreasing the possibility of selecting strains resistant to aPI (16,17,19).…”

“…The effectiveness of photodynamic inhibition as a fungicidal and bactericidal agent has been demonstrated by different authors (17,19,(21)(22)(23), although little is known about aPI, its mechanism of action against dimorphic fungi, and the influence of melanin on the effects of aPI. Considering that melanin has antioxidant properties, the aim of this study was to evaluate the effects of aPI and of classical antifungal drugs in nonmelanized and melanized Paracoccidioides sp.…”

In vitro reduction of pathogenic sporothrix schenckii fungus by photodynamic therapy

“…Yeasts, such as Saccharomyces marxianus, have been used as model organisms to elucidate the types of damage caused by photodynamic therapy (PDT) in eukaryotic cells 14 . This fact has aroused interest in PDT in fungi, and the target has mainly been its use in pathogenic or potentially pathogenic fungi 17 . Considering the potential of this technique in the treatment of fungal infections and the importance of developing new antifungal strategies, PDT can be considered a promising alternative for the treatment of patients with sporotrichosis 18,19 .…”

“…Tests with laser irradiation, or even non-irradiated dye in the presence of yeast suspension, did not show any deleterious effects on the growth of the Sporothrix schenckii complex fungi 13,[15][16][17][18][19] . However, the concentration of 0.1 mg/ml, followed by low power GaAlAs laser irradiation at energy densities of 26.31 J/cm², reduced the number of log CFU mL of the fungus.…”

Efeito da inativação fotodinâmica com fotossensibilizadores fenotiazínicos em microconídios não germinados e germinados dos fungos Fusarium oxysporum, Fusarium moniliforme e Fusarium solani

“…Análises por citometria de fluxo foram utilizadas para avaliar danos na membrana, no material genético e 8 _________________________________________________________________________Introdução para avaliar o estresse oxidativo induzido pela IF (So et al, 2010). A PCR em tempo real tem sido utilizada para avaliar alterações na transcrição gênica em resposta a IF (Almeida et al, 2012). Respostas celulares a IF, como a apoptose, têm sido descritas e investigadas em C.…”