Mechanism Of Trophoblast Cell-derived Microparticles Mediated Immunocontraceptive Response In A Mouse Model

?Objectives?Microparticles(MPs)are extracellular vesicles ranging in size from 100 nm to 1000 nm,which are released by cell membrane structure changes upon activation or apoptosis.Microparticles can carry the immune antigens of the parental cells for intercellular communication.It is believed that trophoblast-derived microparticles(Tr-MPs)play an important role in the establishment and maintenance of pregnancy,but the mechanism is unknown.In this study,we try to prepare Tr-MPs and to explore how Tr-MPs promote the maturation of dendritic cells(DCs)and generate a specific T cell immune response against placental trophoblasts.Through the study of Tr-MPs-mediated immune contraceptive mechanism,this project attempts to explore the key to maintaining balance between implantation and pregnancy,and to find potential novel immunization vaccines.?Methods?1.Establish animal model to study the safety,efficacy and reversibility of Tr-MPs as contraceptive vaccines: study the safety of Tr-MPs and its effects on liver and kidney function in mice;study the effectiveness of Tr-MPs as contraceptive vaccines;2.Study the interaction between Tr-MPs and DCs: flow cytometry and two-photon confocal microscopy to detect the efficiency of DCs uptake of Tr-MPs;in vitro and in vivo study of the effect of Tr-MPs on DCs phenotype;3.To investigate the activation of T cells by Tr-MPs: in vitro and in vivo studies on the activation of mouse T cells by Tr-MPs;to study the effect of Tr-MPs on the functional phenotype of mouse T cells.?Results?1.Tr-MPs have a good contraceptive effect and have little effect on liver and kidney function.After immunized with Tr-MPs,the labor rate of the mice decreased,and the changes of body weight and the levels of ALT,AST and Cr in serum were not significantly different from those of the control group.2.Tr-MPs can be efficiently took up by BMDCs.Affter 48 hours,BMDCs turn to be matured.The expression of costimulatory molecules CD80,CD86,CCR7 and MHCII is up-regulated,and the expression of pro-inflammatory cytokines,such as IL-12,IFN-?,IFN-? and IFN-?,are also increased.3.In vivo experiments,after immunized with Tr-MPs,DCs of draining lymph nodes in mice were activated,and the expression of costimulatory molecules increased.4.In vitro experiments,after taking up Tr-MPs,BMDCs could effectively activate T cell proliferation,but neither Tr-MPs nor immature BMDCs could.5,In vivo experiments,after immunized with Tr-MPs,the draining lymph nodes of the mice turned bigger,and the total number of lymphocytes increased,including both CD4+ and CD8+ T cells.Besides,the rate of IFN-? and IL-17 of T cells in lymph node also increased.6.Proliferated T cells by Tr-MPs are cytotoxic to trophoblast cells,whereas neither na?ve T cells nor antibody-activated T cells.?Conclusion?This study found that Tr-MPs can be taken up by dendritic cells,then promote dendritic cells to secrete cytokines and activate T cells,disrupting the immune balance at the maternal-fetal interface and affecting embryo implantation,which leads to terminate pregnancy in advance and achive contraception.