Fungal extracellular vesicles: modulating host-pathogen interactions by both the fungus and the host

Abstract

The secretion of biomolecules by fungal cells occurs via the conventional export of signal peptide-coupled soluble molecules, but it also results from transport within extracellular vesicles (EV). During the last ten years since the description of this non-conventional secretion pathway, varied, interesting biological roles have been associated with EV release by fungi. The various organic molecules carried by these structures are involved in pathogenesis and immune evasion, and may be associated with cell-cell communication. In regards to host-pathogen interactions, EV roles are diverse and organism-specific, although some features seem to be conserved among the pathogenic fungal organisms studied to date. This review aims to highlight our current understanding of the biologically relevant findings regarding EV released by the pathogenic fungal organisms and describes our knowledge of the roles of EV in host-pathogen interactions.

Keywords: Candida; Cryptococcus; Extracellular vesicles; Fungus; Histoplasma; Paracoccidioides.

Figure 1. Recently discovered interactions between fungal EV and the host’s environment

EV from capsular and acapsular strains of C. neoformans activates macrophages as determined by the production of nitric oxide and cytokines as well as the augmentation of macrophages effector functions (A). Binding of antibody against hsp60 on the surface of H. capsulatum yeast cells modulates the loading of protein cargo in EV (B). EV from P. brasiliensis promotes the polarization of naïve and M2 macrophages towards a M1 phenotype (C). Macrophages and dendritic cells are activated by C. albicans EV, and treatment of G. mellonella with EV from C. albicans protects against a subsequent in vivo challenge with C. albicans yeast cells (D).