Study On The Effect And Mechanism Of Lymphotactin And Its Receptor At Maternal-fetal Interface

Embryos ia an allograft to its mother,but the mother provides a special immune milieu at the maternal-fetal interface to permit rather than reject the embryo growth in the uterus until parturition by establishing precise crosstalk between the mother and the fetus.There are unanswered questions in the maintenance of pregnancy including the poorly understood phenomenon of maternall tolerance to the allogeneic conceptus and the remarkable biological roles of placental trophoblasts that invade the uterine wall.Chemokines are a large family of small(8-12kDa)and structurally related polypeptides that,together with their receptors,control directional cell migration during immune surveillance,inflammation,development,angiogenesis,as well as tumor growth and metastasis.Chemokines are multifunctional molecules initially described as having a role in leukocyte trafficking and later found to participate in developmental processes such as differentiation and directed migration.It is increasingly evident that the gestational uterine microenvironment is characterized,at least in part,by the differential expression and secretion of chemokines that induce selective traffickingof leukocyte subsets to the maternal-fetal interface and regulate multiple events that are closely associated with normal pregnancy.Chemokines are classified into four classes:CXC,CC,C and CX3C.Chemokine receptor are G-protein-coupled seven-transmembrane receptors and named according to the chemokine class they bind.There are two highly homologous C class chemokine genes in human,XCL1 and XCL2,whereas XCL1 gene in mouse is the only one member of the C class chemokine genes.Human and mouse XCL1s share 60%amino acid identity.The XCL1-XCR1 axis was reported to play a key role in the immune system,including the regulation of de dendritc-cell-mediated cytotoxic immune response,the thymic establishment of self-tolerance and the generation of regulatory T cells.Recent studies also demonstrated the importance of XCL1/XCR1in cancer cell proliferation,migration and invasion.So far the role of lymphotactin and its receptor XCR1 at maternal-fetal interface and its possible mechanism have not been reported at home and abroad.In this study,through quantitative Real-time PCR,our group analyzed the expression of chemokine receptors at the decidua in the first trimester.We found high levels of CXCR3,XCR1 mRNA,moderate expression of CCR10,CXCR1,CXCR6,low expression of CCR1,CCR5,CCR6,CCR7,CCR9,CX3CR1 and nearly no expression of CCR2,CCR8,CXCR2,CXCR5.Then we further analyzed the expression of XCL1 and XCR1 in the first trimester and at full term.XCL1 and XCR1 express higher in the first trimester.In addition,by using animal experiments and flow cytometry analysis,we found that the gene and protein expression of XCL1and XCR1 was higher in the early pregnancy,and higher in the spleen and uterus than the bone marrow and peripheral blood.We used HTR-8 cell line as trophoblast cell.The result found that XCL1 could promote the migration and invasion of trophoblast cell in a dose-dependent manner in vitro,by using transwell and scratch adhesion test.Small interfering RNA of XCR1 inhibited the migration and invasion of trophoblast cell.The comparison of XCL1 and XCR1 expression between health control and spontaneous abortion showed that XCL1 and XCR1 mRNA was higher in the spontaneous abortion,especially in the recurrent miscarriage.Poly(I:C)could induce the XCL1 secrection and XCR1 expression in the trophoblast cell,whereas LPS could not.By the poly(I:C)induced abortion murine model,we found DC cell is less in the UMGC(uterine mononuclear and granular cells)than the control group and XCR1expression in DC cells was also lower.But CD8~+XCR1~+cells were higher than the control.Recombination mouse xcl1 increased embryo loss and percentage of CD8~+cells in the uterus,spleen,peripheral blood and bone marrow.We first research the role of XCL1 and XCR1 at the maternal-fetal interface and their regulation of the trophoblast cell migration and invasion.We explore their distribution in decidual in time and space.On allogeneic pregnanc mouse model,we induced the abortion of pregnancy mouse by rm-xcl1.It lays the foundation for our further research in the future.