Maternal and Fetal CD4+CD25+CD127low/- Regulatory T Cells in Pregnancies with Gestational Diabetes, Preeclampsia, and Premature Rupture of Membranes

Abstract Background Regulatory T cells (Tregs) play a crucial role in maternal-fetal tolerance, but little is known about the characteristic of Tregs in peripheral blood (PB), maternal-fetal interface and cord blood (CB) in normal and complicated pregnancies with preeclampsia (PE), gestational diabetes mellitus (GDM) and premature rupture of membranes (PROM). Methods PB, retro-placental blood (RPB), and CB were collected immediately after delivery in women with normal full-term pregnancy (NP), PE, GDM, and PROM. The proportion of CD4 + CD25 + CD127 low/- T cells (Tregs) and the expression of PD-1, GITR, HLA-G and CTLA-4 on T cell subsets were investigated by flow cytometric analysis. The data were analyzed based on sample origins (PB, RPB, and CB) and the obstetrical study groups (NP, PE, GDM, and PROM). Results The proportions of Tregs in PB, RPB, and CB from NP were significantly higher than the other obstetrical groups (P < 0.01, respectively). However no significant differences were present among the PE, GDM and PROM groups (P = NS). The proportion of PD-1 + and GITR + Tregs in RPB and PB as well as PD-1 + Tregs in CB from NP were significantly higher than those of the same origin in each obstetrical study group (P < 0.01, respectively). There were no differences in HLA-G + and CTLA-4 + Tregs between different origins in each obstetrical study group. In NP, the proportion of PD-1 + Tregs was significantly decreased in CB as compared to those of PB and RPB (P < 0.05, respectively). Among the four groups, the proportion of GITR + Tregs were significantly higher in PB as compared to those of CB and RPB (P < 0.01, respectively). The proportion of HLA-G + Tregs in PB was significantly lower than that of CB and RPB (P < 0.01, respectively). The proportion of CTLA-4 + Tregs had no significant differences (P = NS). Conclusions In conclusion, the proportion and characteristics of Tregs vary in the maternal, fetal and maternal-fetal junction at the time of delivery. The different feature and density of Tregs in maternal and fetal tissue may suggest the multiple and complicated roles of Tregs during pregnancy.