Immune Regulation at Maternal-fetal Interface in Early Pregnancy

Decidual immune cells(DICs),including T-cells,regulatory T-cells,macrophages/dendritic cells,natural killer cells,and neutrophils,are resident at the maternal-fetal interface,and play vital roles in regulating trophoblast migration,decidual angiogenesis,immune tolerance,placentation,and decidualization during the early pregnancy.Extensive researches have revealed that these maternal DICs cooperated with each other,or with maternal decidual stromal cells,or with fetal-derived trophoblasts,and further formed a special maternal-fetal cross talk at the maternal-fetal interface,which was essential for the construction and maintenance of physiological pregnancy.Once aberrant cross talk and immune regulation arise,many pregnancy complications will inevitably occur,such as spontaneous abortion,intrauterine growth restriction(IUGR),preeclampsia(PE),and preterm birth.Here,we reviewed how critical immune cells are either enriched or excluded from the decidua,how their function is regulated within the decidua,and how they variously contribute to pregnancy success or failure.