Ound: Protozoan parasites on the genus Leishmania are transmitted by the bite of infected sand flies leading to a wide selection of ailments referred to as leishmaniasis. Based on the species involved, it can produce a self-healing wound to a potentially lethal visceral infection. Recently, we published a seminal work demonstrating that CB2 Agonist supplier leishmanial exosomes (Leish Exo) were released in the lumen of your sand fly midgut and to be co-egested with all the parasite through the blood meal. Leish Exo have been found to stimulate an inflammatory response conducting to exacerbated cutaneous leishmaniasis, also it was shown that these vesicles cargo essential virulence elements like GP63; Based on this, our actual aim was to analyse the influence of GP63-enriched Leish Exo around the modulation of macrophage inflammatory response and its infection in mice. Glycopeptide Inhibitor Storage & Stability Procedures: Making use of Leish Exo isolated from Leishmania amazonensis expressing different levels of GP63 (WT, GP63low, GP63high), we tested their capacity to induce the expression of various inflammatory cytokines (e.g. TNF, IL-6) and chemokines (e.g. CXCL2). Furthermore, LCMS/MS analyses of these numerous Leish Exo preparations happen to be performed. Final results: Results obtained revealed that presence of GP63 differentially influences their expression in macrophages. Of interest, the presence of GP63 was confirmed and to influence the level of Leishmania arginase being enriched in Leish Exo.This latter getting essential inside the regulation of NO activity, it was hence of further interest to test how these distinctive Leish Exo preparations could influence the infection progression in vivo. Consequently, to test this, Balb/c mice have been infected in their hind footpad with stationary L. amazonensis WT or GP63low with or without Leish Exo from each and every three groups of parasites. Summary/conclusion: Data obtained from this study will be additional discussed in the course of the poster presentation, at the same time as the final conclusion in regard for the essential function played by Leishmania GP63 in Leish Exo. Funding: This operate was funded by CIHR and CNPq-Brazil.B-cell population. Our group demonstrated that these cells are able to phagocytose L. (L.) amazonensis promastigotes and participate in immunity against the parasite in murine model of infection by Leishmania (Leishmania) amazonensis. On the other hand, the mechanisms underlying this protection haven’t but been uncovered. In this study, we evaluated the release of extracellular vesicles by B-1 cells uninfected or infected with L. (L.) amazonensis, the role of those particles on macrophages functions and inside the course of experimental infection using the parasite. Procedures: B-1 cells have been purified from peritoneal cavities of BALB/c mice by utilizing antibodies anti-CD23 and anti-CD19 coupled with magnetic microbeads. Purified B-1 cells have been infected with L. (L.) amazonensis promastigotes for 24 h. Extracellular vesicles had been obtained from supernatant by ultracentrifugation. In vitro research had been performed with macrophages differentiated from bone marrow stimulated with EVs from B-1 cells. The experimental infection was carried out with BALB/c mice soon after approval on the study by the ethics and research committee of UNIFESP. Results: Nanotracking analysis (NTA) and scanning electron microscopy showed that uninfected B-1 cells spontaneously released EVs however the parasite stimulated an increase in EVs releasing. The expression from the IL-6 and IL-10 cytokines was considerably greater in macrophages treated with EVs from infected B-1 cells.