Change of CD4+CD25+ Treg percentage and Foxp3 expression level in URSA mouse model

To study the role of CD4+CD25+Treg in unexplained recurrent spontaneous abortion,we investigate the percentage of CD4+CD25+Treg and the Foxp3 expression level in normal pregnancy and abortion mouse model.An immunological model of abortion was used,in which the mating combination CBA/J×DBA/2J represents the abortion group,while using the combination CBA/J×Balb/c as a normal pregnancy control.On 14th day of pregnancy,the females were sacrificed.We analyzed the percentage of CD4+CD25+Treg in spleen cells by flow cytometry,detecte the expression level of Foxp3 by Western blot,and then calculated the ratio of abortions(resorption plus normal implantation sites).The results showed that in spleen,the percentage of CD4+CD25+Treg in CD4+T cells was significantly lower in mice of abortion group compared with those in control group [(10.1±0.59)% vs(15.5±0.78)%,(P0.05)];embryo resorption in abortion group was significantly higher than that in the control group [(25.6±3.5)% vs(2.4±1.6)%,(P0.01)];relative value of Foxp3 band density in abortion group was significantly lower than the normal group [(0.68±0.025) vs(0.30±0.018),(P0.05) ].This study might provide evidence for that high abortion rate may result from the decreased frequencies of CD4+CD25+Treg and low expression level of Foxp3.The lack of CD4+CD25+Treg and its deficiency may be a cause of unexplained recurrent spontaneous abortion.