Fungal Extracellular Vesicles

Abstract

Fungal extracellular vesicles (EVs) are bilayered membranous compartments loaded with proteins, polysaccharides, pigments and nucleic acids. Although microscopic evidence from early studies suggested their existence more than four decades ago, fungal EVs were isolated for the first time in 2007. The involvement of EVs in the deliver of an intracellularly synthesized polysaccharide of Cryptococcus neoformans to the extracellular environment suggested that fungal EVs could play fundamental roles in alternative mechanisms of secretion. Ten years have passed and during this period EVs have been isolated and characterized from culture supernatants of several fungal organisms including both pathogenic and non-pathogenic species. Besides their potential role in secretion, the involvement of fungal EVs in disease development has been speculated. Fungal EVs interact with endothelial cells, macrophages and dendritic cells modulating their activities in vitro. However, the impact of EVs on disease outcome is still controversial. Although a protective effect of fungal EVs was observed in Galleria mellonella larvae challenged with Candida albicans, intravenous administration of EVs in mice along with C. neoformans yeasts was associated with enhancement of brain colonization. EVs apparently participate in fungal physiology through mediating cell wall remodeling and cell-to-cell communication. Fungal EVs have emerged as complex, multifunctional compartments and a full understanding of their roles will require additional years of investigation.