RESUMO
Histoplasma capsulatum is the causative agent of histoplasmosis. Treating this fungal infection conventionally has significant limitations, prompting the search for alternative therapies. In this context, fungal extracellular vesicles (EVs) hold relevant potential as both therapeutic agents and targets for the treatment of fungal infections. To explore this further, we conducted a study using pharmacological inhibitors of chitinase (methylxanthines) to investigate their potential to reduce EV release and its subsequent impact on fungal virulence in an in vivo invertebrate model. Our findings revealed that a subinhibitory concentration of the methylxanthine, caffeine, effectively reduces EV release, leading to a modulation of H. capsulatum virulence. To the best of our knowledge, this is the first reported instance of a pharmacological inhibitor that reduces fungal EV release without any observed fungicidal effects.
RESUMO
In this study, we investigated the influence of fungal extracellular vesicles (EVs) during biofilm formation and morphogenesis in Candida albicans. Using crystal violet staining and scanning electron microscopy (SEM), we demonstrated that C. albicans EVs inhibited biofilm formation in vitro. By time-lapse microscopy and SEM, we showed that C. albicans EV treatment stopped filamentation and promoted pseudohyphae formation with multiple budding sites. The ability of C. albicans EVs to regulate dimorphism was further compared to EVs isolated from different C. albicans strains, Saccharomyces cerevisiae, and Histoplasma capsulatum. C. albicans EVs from distinct strains inhibited yeast-to-hyphae differentiation with morphological changes occurring in less than 4 h. EVs from S. cerevisiae and H. capsulatum modestly reduced morphogenesis, and the effect was evident after 24 h of incubation. The inhibitory activity of C. albicans EVs on phase transition was promoted by a combination of lipid compounds, which were identified by gas chromatography-tandem mass spectrometry analysis as sesquiterpenes, diterpenes, and fatty acids. Remarkably, C. albicans EVs were also able to reverse filamentation. Finally, C. albicans cells treated with C. albicans EVs for 24 h lost their capacity to penetrate agar and were avirulent when inoculated into Galleria mellonella. Our results indicate that fungal EVs can regulate yeast-to-hypha differentiation, thereby inhibiting biofilm formation and attenuating virulence. IMPORTANCE The ability to undergo morphological changes during adaptation to distinct environments is exploited by Candida albicans and has a direct impact on biofilm formation and virulence. Morphogenesis is controlled by a diversity of stimuli, including osmotic stress, pH, starvation, presence of serum, and microbial components, among others. Apart from external inducers, C. albicans also produces autoregulatory substances. Farnesol and tyrosol are examples of quorum-sensing molecules (QSM) released by C. albicans to regulate yeast-to-hypha conversion. Here, we demonstrate that fungal EVs are messengers impacting biofilm formation, morphogenesis, and virulence in C. albicans. The major players exported in C. albicans EVs included sesquiterpenes, diterpenes, and fatty acids. The understanding of how C. albicans cells communicate to regulate physiology and pathogenesis can lead to novel therapeutic tools to combat candidiasis.
Assuntos
Candida albicans , Vesículas Extracelulares , Biofilmes , Ácidos Graxos/farmacologia , Hifas , Saccharomyces cerevisiaeRESUMO
AIM: To evaluate alterations of zinc homeostasis in macrophages exposed to Cryptococcus neoformans. Materials & methods: Using a fluorescent zinc probe-based flow cytometry and atomic absorption spectrometry, zinc levels were evaluated in J774.A1 cell lines exposed to C. neoformans H99 cells. The transcription profile of macrophage zinc related homeostasis genes - metallothioneins and zinc transporters (ZnTs) of the SLC30 and SLC39 (Zrt-Irt-protein) families - was analyzed by quantitative PCR. RESULTS: Macrophage intracellular labile zinc levels decreased following exposure to C. neoformans. A significant decrease in transcription levels was detected in specific ZnTs from both the Zrt-Irt-protein and ZnT families, especially 24 h after infection. CONCLUSION: These findings suggest that macrophages may exhibit zinc depletion in response to C. neoformans infection.