Trypanosoma cruzi-secreted vesicles have acid and alkaline phosphatase activities capable of increasing parasite adhesion and infection

Abstract

Trypanosoma cruzi virulence factors include molecules expressed on the cell surface as well as those secreted or shed into the extracellular medium. Phosphatase activities modulate different aspects of T. cruzi infection, although no studies to date addressed the presence and activity of phosphatases in vesicles secreted by this parasite. Here, we characterized acidic and alkaline secreted phosphatase activities of human-infective trypomastigote forms of T. cruzi from the Y strain and the CL-Brener clone. These are widely studied T. cruzi strains that represent "opposite ends of the spectrum" regarding both in vitro and in vivo behavior. Ecto-phosphatase activities were determined in live parasites, and secreted phosphatase activities were analyzed in soluble protein (SP) and vesicular membrane fractions (VFs) of parasite-conditioned medium. Our analysis using different phosphatase inhibitors strongly suggests that vesicles secreted by Y strain (VF(Y)) and CL-Brener (VF(CLB)) trypomastigotes are derived mostly from the cell surface and from exosome secretion, respectively. Importantly, our results show that the acid phosphatase activities in vesicles secreted by trypomastigotes are largely responsible for the VF-induced increase in adhesion of Y strain parasites to host cells and also for the VF-induced increase in host cell infection by CL-Brener trypomastigotes.

Characterization and Diagnostic Application of Trypanosoma cruzi Trypomastigote Excreted-Secreted Antigens Shed in Extracellular Vesicles Released from Infected Mammalian Cells

“…Interestingly, treatment of mice with EVs shed by axenic trypomastigotes caused a downmodulation of the host immune response that was associated with higher parasitemia and an exacerbated inflammatory response that resulted in increased mortality following infection (26,35). The T. cruzi small membrane proteins (TcSMP) family of proteins or phosphatases detected on T. cruzi EVs has been shown to trigger Ca 2ϩ signaling and lysosome mobilization/exocytosis, events that promote formation of parasitophorous vacuoles and parasite invasion (36,37). A similar modulation of macrophage responses was observed following exposure to purified Leishmania exosomes, a strategy that enhances intracellular parasite survival (38,39).…”

Exosomes in the Pathogenic Protozoan Trypanosoma Cruzi

“…The surviving trypomastigotes transform a few days later either in spherical forms, known as spheromastigotes, or in epimastigote forms. The latter ones migrate to the intestine where they intensely divide and attach, through a specific interaction process where GPI-linked macromolecules exposed on the parasite surface are recognized by components of vesicles contain ecto-phosphatases that could be inhibited by inhibitors such as sodium tartrate and sodium fluoride thus suggesting being acid phosphatases [47]. Inhibitors of phosphotyrosine phoshatase such as o-vanadate also inhibit enzyme activity.…”

“…T. cruzi virulence factors include molecules expressed on the cell surface as well as those secreted or shed into the extracellular medium. Phosphatase activities modulate different aspects of T. cruzi infection, and Neves and colleagues [47] demonstrated the presence and activity of phosphatases in vesicles secreted by Y and CL-Brener (VF-CLB) trypomastigotes suggesting that exosomes are truly involved in T. cruzi invasion ( Figure 5). …”

“…Recently, Ramirez and thors also reported that these results varied according to the strain of T. cruzi used. Evidence was obtained showing that the phosphatases play some role on the process of adhesion of T. cruzi trypomastigotes to the host cell surface and its subsequent internalization [47].…”

Exosomes: potential model for complement-stealth delivery systems

“…Exosomal delivery of virus components and proteins are essential for disease progression in human T-lymphotropic virus type 1 infections (31). The pathomechanism of parasite infections in some cases involves exosomes, where the vesicles can induce adhesion of the pathogen (32).…”