Reproduction Abstracts

Human pregnancy represents a unique immunological environment. However, very little is known about the role of uterine decidual macrophages (dMs) in early human pregnancy. The monocytic cell line (THP1) was activated and polarised to a pro-inflammatory M1 or immunosuppressive M2 M phenotype and the conditioned media was used to treat fetally-derived trophoblast cells. Treatment with M1 conditioned media was found to significantly reduce trophoblast motility in vitro, indicating that M phenotype may have a role in regulating placentation. Primary dMs were isolated from tissue obtained from women undergoing first-trimester terminations of pregnancy. Receptor profiling by flow cytometry demonstrated that dMs have a unique expression profile with expression of both M1 and M2 markers of polarisation. However, they become significantly more M2-like in phenotype as pregnancy progresses, with an increase in CD206 expression and down-regulation of activation markers such as HLA-DR and CD86, between 4 and 14 weeks gestation. In addition, the relative risk for developing preeclampsia was calculated by uterine artery resistance indices (RI) measured by Doppler ultrasound prior to pregnancy termination. DMs isolated from pregnancies with a higher risk of developing preeclampsia (high-RI) were found to have an altered phenotype when compared to Ms from normal risk pregnancies (normal-RI). In conclusion, M polarisation state has been shown to affect macrophage-trophoblast interactions in vitro. Furthermore, there are dynamic changes in dM phenotype during early pregnancy and aberrant dM activation may contribute to a higher risk of developing preeclampsia.