Resumo

Candida albicans is the main causative agent of fungal infections in humans. During the disease establishment, structures involved with pathogenesis are constitutively secreted. Production of extracellular vesicles by C. albicans has already been reported. Here, our goal was to analyze the composition, morphology, kinetics of internalization by host cells and modulatory activity of extracellular vesicles produced by C. albicans. Vesicles from culture supernatant were collected by ultracentrifugation. Vesicular compartments containing lipid bilayer and sizes varying between 50 and 850 nm were observed. Ergosterol, lanosterol and glucosylceramide were detected as major lipids by TLC in vesicular fractions. A total of 57 proteins were characterized by mass spectrometry (MS). Proteins involved with pathogenesis, metabolism of lipids, carbohydrates and proteins, cellular organization and biogenesis, stress response and induction of host immune response were also detected. The presence of Saps, one of the major virulence factors of C. albicans, was confirmed by MS and Western blot. The enzymatic activity of Saps was detected in vitro. The mechanism of extracellular vesicles interaction appears to be similar in MOs and DCs, with a putative involvement of GM1, a glycosphingolipid enriched in lipid domains. Extracellular vesicles were found associated with host cell membrane after 5 min and a complete internalization was observed after 15 minutes. In MOs, extracellular vesicles induced NO production but do not altered CD86 and MHCII expression. RAW264.7 MOs produced higher levels of IL12p40, TGF-β and IL-10, whereas bone marrow-derived MOs produce more IL12p40, TNF-α and IL-10. Treatment of DCs with extracellular vesicles resulted in MHCII and CD86 expression. In addition, an increase of IL-12p40, IL-10, TNF-α and TGF-β secretion by these host cells was detected. In summary, our results demonstrate that extracellular vesicles released by C. albicans carry many virulence factors and are internalized by host cells, where they exert biological effects and modulate their activities.