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H2S and NO affect intracellular killing of Candida albicans modulating GSH levels

Abstract number: P1353

Grosso S., Lucini V., Pannacci M., Caronno A., Scaglione F.

Candida albicans, has become a significant nosocomial pathogen. In macrophages, responsible for control of candida growth, redox status regulates the intracellular killing. Antioxidant mechanisms are likely to quench the reactive oxygen species (ROS) and to protect against any damage but, during infections, these systems are reduced. Glutathione (GSH) and nitric oxide (NO) are important mediators in various physiological and pathological conditions. Recent studies, also, show that endogenous hydrogen sulphide (H2S) could protect cells from oxidative stress by modulating ROS. In this study, we have examined the role of GSH during C. Albicans infection and the relationship between the GSH, H2S and NO in infected murine macrophages.

Methods: J774.1 cells, infected with C. albicans, were maintained for 1 h at 37°C, in culture medium with GSH precursors (NAC, N-acetylcysteine) or with glutathione biosynthesis inhibitors (BSO, Buthionine-sulfoximine). In addition, in infected macrophages H2S was induced with Sodium hydrosulphide (NaHS) or inhibited whit DL-propargylglycine (PAG). GSH concentration was spectrophotometrically assayed. To determine whether GSH and H2S were, also, important for the intracellular killing of C. albicans, infected J774A.1 were lysed and the surnatant was plated on Sabouraud dextrose agar. The number of viable candida was quantified with 10-fold dilutions spread. In infected macrophages, NO production was assessed by measuring of intracellular nitrite concentrations or by expression of inducible nitric oxide synthase (iNOS), detected by Real Time PCR.

Results: Treatment with BSO significantly reduced killing of C. albicans and GSH concentration. NAC addition to infected macrophages, increased GSH levels and induced a significant reduction in the viability of C. albicans (P < 0.001). NaHS caused an increase of GSH levels and a decrease of viable yeast, while PAG reduced GSH concentration and intracellular killing. In the presence of BSO, nitrite and iNOS was increased by 2-fold respect to unstimolated cells (P < 0.001), while NAC decreased iNOS synthesis and intracellular NO concentration. Moreover, NaHS significantly inhibited NO production, while PAG caused iNOS expression (P < 0.001).

Conclusions: GSH may play an important role in killing of C. albicans and in control of opportunistic fungal infections. We have also provided to evidence that H2S could modulate intracellular killing by increasing GSH levels and inhibiting NO synthesis.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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