Compositional and immunobiological analyses of extracellular vesicles released by Candida albicans.

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Compositional and immunobiological analyses of extracellular vesicles released by Candida albicans.

Cell Microbiol. 2014 Oct 6;

Authors: Vargas G, Rocha JD, Oliveira DL, Albuquerque PC, Frases S, Santos SS, Nosanchuk JD, Gomes AM, Soares Medeiros LC, Miranda KR, Sobreira T, Nakayasu ES, Arigi EA, Casadevall A, Guimaraes AJ, Rodrigues ML, Freire-de-Lima CG, Almeida IC, Nimrichter L

Abstract
The release of extracellular vesicles (EV) by fungal organisms is considered an alternative transport mechanism to trans-cell wall passage of macromolecules. Previous studies have revealed the presence of EV in culture supernatants from fungal pathogens, such as Cryptococcus neoformans, Histoplasma capsulatum, Paracoccidioides brasiliensis, Sporothrix schenckii, Malassezia sympodialis and Candida albicans. Here we investigated the size, composition, kinetics of internalization by bone-marrow derived murine macrophages (MO) and dendritic cells (DC), and the immunomodulatory activity of C. albicans EV. We also evaluated the impact of EVs on fungal virulence using the Galleria mellonella larvae model. By transmission electron microscopy and dynamic light scattering we identified two populations ranging from 50-100 and 350-850 nm. Two predominant seroreactive proteins (27 and 37 kDa) and a group of polydispersed mannoproteins were observed in EV by immunoblotting analysis. Proteomic analysis of C. albicans EV revealed proteins related to pathogenesis, cell organization, carbohydrate and lipid metabolism, response to stress and several other functions. The major lipids detected by thin layer chromatography were ergosterol, lanosterol and glucosylceramide. Short exposure of MO to EV resulted in internalization of these vesicles and production of nitric oxide, IL-12, TGF-β and IL-10. Similarly, EV-treated DC produced IL- 12p40, IL-10 and TNF-α. In addition, EV treatment induced the upregulation of CD86 and MHC-II. Inoculation of G. mellonella larvae with EV followed by challenge with C. albicans reduced the number of recovered viable yeasts in comparison to infected larvae control. Taking together, our results demonstrate that C. albicans EV were immunologically active and could potentially interfere with the host responses in the setting of invasive candidiasis.

PMID: 25287304 [PubMed - as supplied by publisher]