Extracellular vesicles from Trypanosoma cruzi-dendritic cell interaction show modulatory properties and confer resistance to lethal infection as a cell-free based therapy strategy.

Extracellular vesicles (EVs) include a heterogeneous group of particles. Microvesicles, apoptotic bodies and exosomes are the most characterized vesicles. They can be distinguished by their size, morphology, origin and molecular composition. To date, increasing studies demonstrate that EVs mediate intercellular communication. EVs reach considerable interest in the scientific community due to their role in diverse processes including antigen-presentation, stimulation of anti-tumoral immune responses, tolerogenic or inflammatory effects. In pathogens, EV shedding is well described in fungi, bacteria, protozoan and helminths parasites. For Trypanosoma cruzi EV liberation and protein composition was previously described. Dendritic cells (DCs), among other cells, are key players promoting the immune response against pathogens and also maintaining self-tolerance. In previous reports we have demonstrate that T. cruzi downregulates DCs immunogenicity in vitro and in vivo. Here we analyze EVs from the in vitro interaction between blood circulating trypomastigotes (Tp) and bone-marrow-derived DCs. We found that Tp incremented the number and the size of EVs in cultures with DCs. EVs displayed some exosome markers and intracellular RNA. Protein analysis demonstrated that the parasite changes the DC protein-EV profile. We observed that EVs from the interaction of Tp-DCs were easily captured by unstimulated-DCs in comparison with EVs from DCs cultured without the parasite, and also modified the activation status of LPS-stimulated DCs. Noteworthy, we found protection in animals treated with EVs-DCs+Tp and challenged with T. cruzi lethal infection. Our goal is to go deep into the molecular characterization of EVs from the DCs-Tp interaction, in order to identify mediators for therapeutic purposes.

Modulatory Effect of Trypanosoma cruzi Infective Stages in Different Dendritic Cell Populations in vitro.

Trypanosoma cruzi is a protozoan parasite that infects at least 7 million persons in the world (OMS, 2019). In endemic areas, infection normally occurs by vectorial transmission; however, outside, it normally happens by blood and includes congenital transmission. The persistence of T. cruzi during infection suggests the presence of immune evasion mechanisms and the modulation of the anti-parasite response to a profile incapable of eradicating the parasite. Dendritic cells (DCs) are a heterogeneous population of antigen-presenting cells (APCs) that patrol tissues with a key role in mediating the interface between the innate and adaptive immune response. Previous results from our lab and other groups have demonstrated that T. cruzi modulates the functional properties of DCs, in vitro and in vivo. During vectorial transmission, metacyclic (m) trypomastigotes (Tps) eliminated along with the insect feces reach the mucous membranes or injured skin. When transmission occurs by the hematic route, the parasite stage involved in the infection is the circulating or blood (b) Tp. Here, we studied in vitro the effect of both infective mTp and bTp in two different populations of DCs, bone marrow-derived DCs (BMDCs) and XS106, a cell line derived from epidermal DCs. Results demonstrated that the interaction of both Tps imparts a different effect in the functionality of these two populations of DCs, suggesting that the stage of T. cruzi and DC maturation status could define the immune response from the beginning of the ingress of the parasite, conditioning the course of the infection.