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Ke-Ming Xie, Xiao-Fan Hou, Ming-Qing Li and Da-Jin Li

Nometastatic gene 23-H1 (NME1, also known as nm23-H1) is a wide-spectrum tumor metastasis suppressor gene that plays an important role in suppressing the invasion and metastasis of tumor cells. It has been demonstrated that NME1 is also expressed in human first-trimester placenta, but its function at maternal–fetal interface is not clear. The present study aimed to elucidate the biological function of NME1 at the maternal–fetal interface, especially on invasion of the human extravillous cytotrophoblasts (EVCTs). NME1 has been identified in both human trophoblast cells and decidual stromal cells (DSCs) in early pregnancy. We have proved that NME1 silencing in vitro increases the titin protein translation in the invasive EVCTs. Moreover, NME1 can inactivate the phospho-extracellular signal-regulated kinase 1/2 (P-ERK1/2) in trophoblasts in a time-dependent manner, and U0126, an inhibitor of MAPK/ERK, can inhibit partly the enhanced invasiveness and titin expression in trophoblasts induced by NME1 silencing. Interestingly, the expression of NME1 in either villi or decidua is higher significantly in miscarriage than that of the normal early pregnancy. These findings first reveal that the NME1 expressed in trophoblasts and DSCs controls the inappropriate invasion of human first-trimester trophoblast cells via MAPK/ERK1/2 signal pathway, and the overexpression of NME1 at maternal–fetal interface leads to pregnancy wastage.

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Hui Li, Yu-Han Meng, Wen-Qing Shang, Li-Bing Liu, Xuan Chen, Min-Min Yuan, Li-Ping Jin, Ming-Qing Li and Da-Jin Li

Chemokine CCL24, acting through receptor CCR3, is a potent chemoattractant for eosinophil in allergic diseases and parasitic infections. We recently reported that CCL24 and CCR3 are co-expressed by trophoblasts in human early pregnant uterus. Here we prove with evidence that steroid hormones estradiol (E), progesterone (P), and human chorionic gonadotropin (hCG), as well as decidual stromal cells (DSCs) could regulate the expression of CCL24 and CCR3 of trophoblasts. We further investigate how trophoblast-derived CCL24 mediates the function of trophoblasts in vitro, and conclude that CCL24/CCR3 promotes the proliferation, viability and invasiveness of trophoblasts. In addition, analysis of the downstream signaling pathways of CCL24/CCR3 show that extracellular signal-regulated kinases (ERK1/2) and phosphoinositide 3-kinase (PI3K) pathways may contribute to the proliferation, viability and invasiveness of trophoblasts by activating intracellular molecules Ki67 and matrix metallopeptidase 9 (MMP9). However, we did not observe any inhibitory effect on trophoblasts when blocking c-Jun N-terminal kinase (JNK) or p38 pathways. In conclusion, our data suggests that trophoblast-derived CCL24 at the maternal-fetal interface promotes trophoblasts cell growth and invasiveness by ERK1/2 and PI3K pathways. Meanwhile, pregnancy-related hormones (P and hCG), as well as DSCs could up-regulate CCL24/CCR3 expression in trophoblasts, which may indirectly influence the biological functions of trophoblasts. Thus, our results provide a possible explanation for the growth and invasion of trophoblasts in human embryo implantation.

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Wen-Hui Zhou, Lin Dong, Mei-Rong Du, Xiao-Yong Zhu and Da-Jin Li

Immune regulation during pregnancy is complex, and thus an optimal therapy for pregnancy complications is always a big challenge to reproductive medicine. Cyclosporin A (CsA), a potent immunosuppressant, prevents rejection of allografts by hosts, but little is known about the modulating effect of CsA on the materno-fetal relationship. Here, pregnant CBA/J females mated with DBA/2 males as an abortion-prone model were administered with CsA on day 4.5 of gestation, and the pregnant CBA/J females mated with BALB/c males were established as successful pregnancy control. It was demonstrated that administration of CsA at the window of implantation significantly up-regulated the expression of CTLA-4, while down-regulating the levels of CD80, CD86, and CD28 at the materno-fetal interface in the CBA/J×DBA/2 abortion-prone matings, and the embryo resorption rate of the abortion-prone matings reduced significantly after CsA treatment, implying that modulation of costimulatory molecule expression by CsA might contribute to preventing the fetus from maternal immune attack. In addition, treatment with CsA induced enhanced growth and reduced cell apoptosis of the murine trophoblast cells. Together, these findings indicate that CsA has a beneficial effect on the materno-fetal interface in abortion-prone matings, leading to a pregnancy outcome improvement, which might provide new therapeutics for spontaneous pregnancy wastage.

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Yi Lin, Huiqi Wang, Wenjing Wang, Shan Zeng, Yanmin Zhong and Da-Jin Li

Both regulatory T cells and regulatory natural killer (NK) cells may play essential roles in the maintenance of pregnancy. In this study, we show that a significantly high percentage of spontaneous embryo loss was observed in both allogeneic and syngeneic pregnant non-obese diabetic (NOD) mice. The percentage of embryo loss in allogeneic pregnant mice was further increased by the administration of anti-asialo ganglio-N-tetraosylceramide to deplete NK cells, but was decreased by the adoptive transfer of ITGA2+ISG20+ (CD49b+ CD25+) NK cells from normal mice. No such trend was observed in syngeneic pregnant NOD mice. The pattern of CXCR4 (specific receptor for CXCL12) expression on NK cells was analyzed and NK-cell migration was confirmed by in vitro and in vivo migratory assays. Since CXCL12 production by murine trophoblast cells was confirmed previously, our findings suggest that the recruitment of peripheral CXCR4-expressing ITGA2+ISG20+ NK cells into pregnant uteri may be important in the regulation of feto-maternal tolerance.

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Hui-Li Yang, Wen-Jie Zhou, Kai-Kai Chang, Jie Mei, Li-Qing Huang, Ming-Yan Wang, Yi Meng, Si-Yao Ha, Da-Jin Li and Ming-Qing Li

The dysfunction of NK cells in women with endometriosis (EMS) contributes to the immune escape of menstrual endometrial fragments refluxed into the peritoneal cavity. The reciprocal communications between endometrial stromal cells (ESCs) and lymphocytes facilitate the development of EMS. However, the mechanism of these communications on cytotoxicity of natural killer (NK) cells in endometriotic milieus is still largely unknown. To imitate the local immune microenvironment, the co-culture systems of ESCs from patients with EMS and monocyte-derived macrophages or of ESCs, macrophages and NK cells were constructed. The cytokine levels in the co-culture unit were evaluated by ELISA. The expression of functional molecules in NK cells was detected by flow cytometry (FCM). The NK cell behaviors in vitro were analyzed by cell counting kit-8 and cytotoxic activation assays. After incubation with ESCs and macrophages, the expression of CD16, NKG2D, perforin and IFN-γ, viability and cytotoxicity of NK cells were significantly downregulated. The secretion of interleukin (IL)-1β, IL-10 and transforming growth factor (TGF)-β in the co-culture system of ESCs and macrophages was increased. Exposure with anti-IL-10 receptor β neutralizing antibody (αhIL-10Rβ) or αTGF-β could partly reverse these effects of ESCs and macrophages on NK cells in vitro. These results suggest that the interaction between macrophages and ESCs downregulates cytotoxicity of NK cells possibly by stimulating the secretion of IL-10 and TGF-β, and may further trigger the immune escape of ectopic fragments and promote the occurrence and the development of EMS.

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Songcun Wang, Fengrun Sun, Mutian Han, Yinghua Liu, Qinyan Zou, Fuxin Wang, Yu Tao, Dajin Li, Meirong Du, Hong Li and Rui Zhu

There is delicate crosstalk between fetus-derived trophoblasts (Tros) and maternal cells during normal pregnancy. Dysfunctions in interaction are highly linked to some pregnancy complications, such as recurrent spontaneous abortion (RSA), pre-eclampsia and fetal growth restriction. Hyaluronan (HA), the most abundant component of extracellular matrix, has been reported to act as both a pro- and an anti-inflammatory molecule. Previously, we reported that HA promotes the invasion and proliferation of Tros by activating PI3K/Akt and MAPK/ERK1/2 signaling pathways. While lower HA secretion by Tros was observed during miscarriages than that during normal pregnancies, in the present study, we further confirmed that higher secretion of HA by Tros could induce M2 polarization of macrophages at the maternal–fetal interface by interacting with CD44 and activating the downstream PI3K/Akt-STAT-3/STAT-6 signaling pathways. Furthermore, HA could restore the production of IL-10 and other normal pregnancy markers by decidual macrophages (dMφs) from RSA. These findings underline the important roles of HA in regulating the function of dMφs and maintaining a normal pregnancy.