IL-24 Expression at Maternal-fetal Interface and Its Roles in Trophoblast Invasion

In this study, the expression of IL-24 at maternal-fetal interface and the roles in extravillous trophoblast （the TEV-1 cell line） invasion were examined. Immunohistochemistry was used to detect the expression of IL-24 in villi and decidual tissue. The proliferation of TEV-1 cells under the effect of IL-24 was measured by MTT assay. The invasiveness of TEV-1 cells under the effect of recombinant IL-24 （rhIL-24） was examined by transwell system. Immunohistochemical detection showed that IL-24 was expressed in the villi and decidual tissue, and distributed in villous column, trophoblasts, stroma and blood vessels. The proliferation of TEV-1 cells was not inhibited by rhIL-24 of various concentrations. The examination of invasion in vitro showed that rhIL-24 could inhibit the invasion of TEV-1 cells in a concentration-dependent manner. The results suggested IL-24 could inhibit the invasion of TEV-1 cells. Therefore, IL-24 produced by maternal-fetal interface in human first trimester pregnancy may influence the invasion of trophoblasts and is involved in normal pregnancy.

Effect of Leptin on Cytotrophoblast Proliferation and Invasion

The effects of leptin on cytotrophoblast proliferation and invasion activity were investigated. Immunohistochemistry was used to determine the placental expression of leptin in first-trimester pregnancy. By using RT-PCR and quantitative real-time PCR, the expression of leptin in cytotrophoblast and the effect of leptin on cytotrophoblast secretion were detected. The potential of cell proliferation, invasiveness and migration was assessed by MTT, Transwell invasion assay and migration assay respectively when the cytotrophoblast was cultured with different concentrations of leptin. The results showed that： （1） Leptin was distributed diffusely around cell membrane, in cytoplasma, and on nuclear mem- brane of cytotrophoblast; （2） Leptin mRNA was expressed in cytotrophoblast. Ten ng/mL leptin could promote the secretion of cytotrophoblast significantly （P〈0.01）; （3） After culture with different concentrations of leptin for 24 h or longer, the proliferation of cytotrophoblast was inhibited, while in 24 h leptin could promote cytotrophoblast invasion and migration. Leptin at a concentration of 500 ng/mL could promote cytotrophoblast invasiveness and migration significantly as compared with controls （P〈0.05）. It was suggested that leptin could inhibit cytotrophoblast proliferation, and promote cytotro- phoblast invasion and migration activity.

Effect of Ephrin-A1/EphA2 on Invasion of Trophoblastic Cells

The effect of axon guidance factors ephrin-A1/EphA2 on the invasion of trophoblastic cells and the possible mechanism were investigated in this study. The expression of EphA2 in vascular endothelial cells was detected by immunohistochemistry. The proliferation and invasion of TEV-1 cells （an extravillous trophoblastic cell line） in first trimester were determined by cell counting kit-8 （CCK-8） and Transwell invasion assay. Real-time PCR was used to detect the expression ofephrin-A1 in TEV-I cells treated with EphA2 at different concentrations （10, 50, 100, 500, 1000 and 5000 μg/L）. The results showed： （1） EphA2 was expressed in the vascular endothelial cells; （2） EphA2 could promote the proliferation of TEV-1 cells. The proliferative capacity reached a peak in TEV-1 cells treated with 100 μg/L EphA2 （P〈0.05）; （3） EphA2 could increase the invasion of TEV-1 cells. The invasive ability was the greatest in TEV-1 cells treated with 500 pg/L EphA2 （P〈0.05）; （4） in the presence of EphA2 （0-500 μg/L）, the expression of ephrin-A1 was increased concentration-dependently （P〈0.05）, but when the concentration of EphA2 was over 500 μg/L, the expression of ephrin-A 1 ceased to increase （P〉0.05）. It was concluded that EphA2 can promote the invasion and proliferation of the human extravillous trophoblastic cells probably by regulating the ephrin-A1 ligand.

Three macrophage subsets are identified in the uterus during early human pregnancy

Macrophages are crucial for a successful pregnancy, and malfunctions of decidual macrophages correlate with adverse pregnancyoutcomes, such as spontaneous abortion and preeclampsia. Previously, decidual macrophages were often thought to be a singlepopulation. In the present study, we identified three decidual macrophage subsets, CCR2−CD11cLO (CD11clow, ~80%), CCR2−CD11cHI (CD11chigh, ~5%), and CCR2+CD11cHI (CD11chigh, 10–15%), during the first trimester of human pregnancy by flowcytometry analysis. CCR2−CD11cLO macrophages are widely distributed in the decidua, while CCR2−CD11cHI and CCR2+CD11cHImacrophages are primarily detected close to extravillous trophoblast cells according to immunofluorescence staining. According toRNA sequencing bioinformatics analysis and in vitro functional studies, these three subsets of macrophages have differentphagocytic capacities. CCR2+CD11cHI macrophages have pro-inflammatory characteristics, while the CCR2−CD11cHI population issuggested to be anti-oxidative and anti-inflammatory due to its high expression of critical heme metabolism-related genes,suggesting that these two subsets of macrophages maintain an inflammatory balance at the leading edge of trophoblast invasionto facilitate the clearance of pathogen infection as well as maintain the homeostasis of the maternal-fetal interface. The presentstudy physiologically identifies three decidual macrophage subsets. Further clarification of the functions of these subsets willimprove our understanding of maternal-fetal crosstalk in the maintenance of a healthy pregnancy.