8th ASM conference on Candida and candidiasis: molecular tools provide insights into host-pathogen interactions

Response to oxidative stress in eight pathogenic yeast species of the genus Candida

In the course of an infection, the formation of reactive oxygen species by phagocytes and the antioxidant defense mechanisms of microorganisms play a crucial role in pathogenesis. In this study, isolates representing 8 pathogenic Candida species-Candida albicans, Candida dubliniensis, Candida famata, Candida glabrata, Candida guilliermondii, Candida krusei, Candida parapsilosis and Candida tropicalis-were compared with regard to their resistance to oxidative stress in vitro. We evaluated degree of resistance, induction of oxidative damage, capacity to adapt, and induction of antioxidant enzymes. The species showed variable sensitivity to oxidative attack. C. albicans, C. glabrata, and C. krusei were more resistant to oxidative stress under the conditions tested; C. parapsilosis and C. tropicalis presented medium resistance; and C. dubliniensis, C. famata, and C. guilliermondii were more sensitive. The overall greater resistance to oxidative stress of C. albicans and C. glabrata may provide an advantage to these species, which are the major causative agents of candidiasis.

HIV aspartyl protease inhibitors as promising compounds against Candida albicans André Luis Souza dos Santos

Cells of Candida albicans (C. albicans) can invade humans and may lead to mucosal and skin infections or to deep-seated mycoses of almost all inner organs, especially in immunocompromised patients. In this context, both the host immune status and the ability of C. albicans to modulate the expression of its virulence factors are relevant aspects that drive the candidal susceptibility or resistance; in this last case, culminating in the establishment of successful infection known as candidiasis. C. albicans possesses a potent armamentarium consisting of several virulence molecules that help the fungal cells to escape of the host immune responses. There is no doubt that the secretion of aspartyl-type proteases, designated as Saps, are one of the major virulence attributes produced by C. albicans cells, since these hydrolytic enzymes participate in a wide range of fungal physiological processes as well as in different facets of the fungal-host interactions. For these reasons, Saps clearly hold promise as new potential drug targets. Corroborating this hypothesis, the introduction of new anti-human immunodeficiency virus drugs of the aspartyl protease inhibitor-type (HIV PIs) have emerged as new agents for the inhibition of Saps. The introduction of HIV PIs has revolutionized the treatment of HIV disease, reducing opportunistic infections, especially candidiasis. The attenuation of candidal infections in HIV-infected individuals might not solely have resulted from improved immunological status, but also as a result of direct inhibition of C. albicans Saps. In this article, we review updates on the beneficial effects of HIV PIs against the human fungal pathogen C. albicans, focusing on the effects of these compounds on Sap activity, growth behavior, morphological architecture, cellular differentiation, fungal adhesion to animal cells and abiotic materials, modulation of virulence factors, experimental candidiasis infection, and their synergistic actions with classical antifungal agents.