Vesicles as Vehicles for Virulence

Abstract

Parasites have long been known to influence host responses to infection through the secretion of virulence factors. Extracellular vesicles are emerging as an important mediator of these manipulations, and a new study by Szempruch et al suggests they could have a critical role in host responses to African trypanosome infections.

Extracellular Vesicles from the Protozoa Acanthamoeba castellanii: Their Role in Pathogenesis, Environmental Adaptation and Potential Applications

“…They communicate with cells of the host immune system, are involved in inflammatory processes and protein export pathways. Some of the publications have also demonstrated the importance of these exosomes as a therapeutic target potential for infectious diseases [70,78].…”

“…Besides A. castellanii , the role of EVs in the process of pathogenesis in protozoa and other microorganisms has been described in some species extensively [44,45,47,48,62,63,66,70,73,78,92,93]; however, it is necessary to have additional understanding of these EVs functions in both pathogenesis and in the ecological regulation that these molecules can exert between cells or in the microbial community, such as in a biofilm (Figure 2). As for the biogenesis of these exosomes in A. castellanii , their mechanisms have not been elucidated yet, requiring further investigation.…”

Extracellular vesicles and vesicle-free secretome of the protozoa Acanthamoeba castellanii under homeostasis and nutritional stress and their damaging potential to host cells

“…However, morphological and biochemical characteristics indicate that they are similar to those described in several mammalian cells [ 35 ], containing lipids, nucleic acids, protein and polysaccharide components [ 31 , 36–38 ]. In the case of important human fungal pathogens, many of those components are associated with virulence [ 33 , 36 , 37 , 39 , 40 ].…”

“…The production of EVs have also been described in such protozoa as Plasmodium sp [ 41 ]., Leishmania donovani and L. major [ 42 , 43 ], Trypanosoma brucei [ 44 , 45 ], T. cruzii [ 46 , 47 ], in helmints such as the nematodes Echinostoma caproni and Fasciola hepatica [ 48 ], Helingmosomoides polygrus [ 49 ], Teladorsagia circumcincta [ 50 ], the trematode Dicrocoelium dendriticum [ 51 ] and the amoeba Dictyostelium discoideum [ 52 ]. Some reports have stated the importance of these exosomes during host-parasite interaction, working as communication mediators between the different cells from distinct organisms, therefore bearing a potential therapeutic target for infectious diseases [ 40 , 41 ].…”

“…The secretory mechanisms used by amoebas are still unclear, but there is a parallel to the release of exosomes described in eukaryotes such as parasites, fungi and mammals [ 53–56 ]. In these models, EVs have been described to be involved in the secretion of proteinases into the extracellular environment, with important implications for the pathogenesis and virulence [ 18 , 40 , 41 , 57 ]; EVs from Acanthamoeba sp. may contain important virulence factors which, when secreted, could also damage host tissues.…”