Characterization of Extracellular Vesicles from Attenuated and Virulent Leishmania amazonensis Promastigotes Reveals Distinct Proteomic Signatures

Leishmaniasis is a group of endemic diseases caused by different species of Leishmania. Virulence factors produced by Leishmania can be found in extracellular vesicles (EVs), a heterogeneous group of particles released by cells that are involved in cell-to-cell communication. Herein, we demonstrated that Leishmania amazonensis subjected to three in vivo passages exhibited exacerbated virulence, while prolonged culture resulted in an attenuated profile. The morphological characterization of EVs released by these parasites showed no significant differences. However, proteomic analysis revealed enrichment of proteins associated with proteolysis in EVs released by virulent parasites. In addition, these EVs showed significantly higher proteasome activity compared to EVs from attenuated L. amazonensis promastigotes. Attenuated and virulent parasites incorporated EVs. However, we observed a significant increase in murine macrophage infectivity by virulent parasites following uptake of autologous EVs. Thus, our findings show that L. amazonensis parasites with distinct virulence profiles release EVs with differences in the relative abundance of their protein cargo, which may contribute to the maintenance or enhancement of parasite infectivity.