Studies On The Influence Of PD-1 /PD-L1 Pathway On Decidua Macrophages In Recurrent Spontaneous Abortion

Background and purpose : At present,Recurrent spontaneous abortion（RSA）has become a concern of obstetrics and reproductive department in the world.It not only causes trauma to the patient’s physical health,but also has an impact on the patient’s mental health and family harmony.The incidence rate of RSA in women of childbearing age ranges from 1 to 5%.The etiology of RSA is extremely complicated,of which 50% is unknown.Decidual macrophage is one of the key cells in immune tolerance,trophoblast invasion,angiogenesis and spiral artery remodeling,and phagocytose apoptotic cells.PD-1/PD-L1 is an immunosuppressive co-signal（immune checkpoint）and participate in the induction of immune tolerance,inhibition of immune response and tumor immune escape.The expression of PD-L1 in villus tissue,and PD-1 in decidual macrophages and its surface,and the effect of PD-1/PD-L1 on the differentiation of monocyte are analyzed.Methods: In villus tissue,Western Bolt was used to detect the protein of PD-L1 and in order to detect the mRNA of PD-L1 we use qPCR.In decidual tissue,flow cytometry was used to measure the macrophages and the expression of PD-1.We use PMA to induce THP-1 cell,cell differentiation was induced by IL-4,LPS and IFN-γ.Blank group,stimulation group（IL-4,LPS,IFN-γ）and PD-1 blocking group（IL-4,LPS,IFN-γ,PD-1antibody）were established,flow cytometry was used to detect cell surface molecules to determine the differentiation of mononuclear macrophages.Results :（1）Western Bolt and qPCR results showed that PD-L1 was expressed in the villous tissues,but the expression of PD-L1 in the RSA group was lower than that in the normal group;（2）Flow cytometry results showed that both M1 and M2 macrophages were expressed in macrophages of the decidua tissue in two groups.M2 cell were main type,CD163+CD206+ was dominant in M2.But in the RSA group there was no significant difference between M1 and M2.CD80+ was dominant in both M1 type;（3）Cell differentiation: THP-1 cells showed M1 and M2 types after stimulation,of which M2 type was dominant,and CD206+ was dominant in M2 type and CD86+ was dominant in M1 type.After adding PD-1 blockade,compared with the stimulation group,the proportion of M1 type increased and M2 type decreased,and have statistically significance.Conclusion: PD-L1 exists in villus tissue,PD-L1 was reduced in RSA group,and the decidual tissue migrate to M2-type macrophages.Both types of macrophages express PD-1.blocking the PD-1 on cell surface can change the differentiation of macrophages into M1 type.