Echinococcus granulosus extracellular vesicles and their cargo in drug response: influence on initial immune response

Abstract Background Echinococcus granulosus sensu lato species complex, causing cystic echinococcosis in both humans and animals, represent one of the most widespread zoonoses of medical importance, which evolved manipulating the immune response of their hosts. Parasite-derived small extracellular vesicles (sEVs) are involved in the interaction between parasites and hosts, which are implicated in pathogenesis, proliferation, and signal transduction. The characteristics of E. granulosus sEVs from protoscoleces and their interaction with host-dendritic cells (DCs) have been reported, however, the effect on the initial immune response of sEVs recovered during parasite pharmacological treatment still remains unexplored. Methods Here, we isolated and characterized sEVs from control and drug-treated protoscoleces using ultracentrifugation, transmission electron microscopy, dynamic light scattering and proteomic analysis. Also, we evaluated the cytokine response profile induced on murine bone marrow derived dendritic cells (BMDCs) by qPCR. Results Small EVs isolated, with conventional size between 50 to 200 nm, independent of drug treatment, showed more than 500 cargo proteins and prominently 20 known antigens and 70 potential antigenic proteins, several integral transmembrane and soluble proteins mainly associated with signal transduction, immunomodulation, scaffolding factors, extracellular matrix-anchoring and lipid transport. The identity and abundance of proteins in the sEV-cargo from metformin and ABZSO-treated parasites were determined by proteomic analysis, detecting 107 and 8 exclusive proteins, respectively that include proteins related to the mechanisms of drug action. Previously, we have shown that sEVs are efficiently uptaken by DCs and that the high-abundance of antigens present in sEVs promoted the DCs maturation and modified their phenotype. Here, we have determined that the interaction of murine BMDCs with sEVs derived from control and drug-treated parasites as albendazole and metformin, increased the expression of pro-inflammatory cytokines such as IL-12 compared to control cells. Additionally, protoscolex-derived vesicles from metformin treatments induced the production of IL-6, TNF-α and IL-10. Nevertheless, the expression of IL-23 and TGF-β was downregulated. Conclusions We demonstrated that sEV-cargo derived from drug-treated- E. granulosus protoscoleces have immunomodulatory functions, which enhance DCs activation toward a type 1 pro-inflammatory profile promoting a more restrictive response against the parasite and therefore contributing to propound a new approach for prevention and treatment of secondary echinococcosis.