SPRY4 regulates trophoblast proliferation and apoptosis via regulating IFN-γ-induced STAT1 expression and activation in recurrent miscarriage

Inflammatory shift alterations of proinflammatory and anti-inflammatory cytokines in unexplained recurrent miscarriage patients

This study aimed to investigate the pro-inflammatory and anti-inflammatory cytokines status in the peripheral blood of uRM patients. The plasma pro-inflammatory (IFN-γ, IL-6, IL-1β, and TNF-α) and anti-inflammatory (TGF-β1, IL-10, and IL-4) cytokines of 25 patients with uRM were compared to 33 women with a successful pregnancy. It was concluded that patients with uRM have an excess pro-inflammatory cytokines status.

Maternal-fetal immunity and recurrent spontaneous abortion

Recurrent Spontaneous Abortion (RSA) is a common pregnancy complication, that has multifactorial causes, and currently, 40%-50% of cases remain unexplained, referred to as Unexplained RSA (URSA). Due to the elusive etiology and mechanisms, clinical management is exceedingly challenging. In recent years, with the progress in reproductive immunology, a growing body of evidence suggests a relationship between URSA and maternal-fetal immunology, offering hope for the development of tailored treatment strategies. This article provides an immunological perspective on the pathogenesis, diagnosis, and treatment of RSA. On one hand, it comprehensively reviews the immunological mechanisms underlying RSA, including abnormalities in maternal-fetal interface immune tolerance, maternal-fetal interface immune cell function, gut microbiota-mediated immune dysregulation, and vaginal microbiota-mediated immune anomalies. On the other hand, it presents the diagnosis and existing treatment modalities for RSA. This article offers a clear knowledge framework for understanding RSA from an immunological standpoint. In conclusion, while the "layers of the veil" regarding immunological factors in RSA are gradually being unveiled, our current research may only scratch the surface. In terms of immunological etiology, effective diagnostic tools for RSA are currently lacking, and the efficacy and safety of immunotherapies, primarily based on lymphocyte immunotherapy and intravenous immunoglobulin, remain contentious.

Role of SPRY4 in health and disease

SPRY4 is a protein encoding gene that belongs to the Spry family. It inhibits the mitogen-activated protein kinase (MAPK) signaling pathway and plays a role in various biological functions under normal and pathological conditions. The SPRY4 protein has a specific structure and interacts with other molecules to regulate cellular behavior. It serves as a negative feedback inhibitor of the receptor protein tyrosine kinases (RTK) signaling pathway and interferes with cell proliferation and migration. SPRY4 also influences inflammation, oxidative stress, and cell apoptosis. In different types of tumors, SPRY4 can act as a tumor suppressor or an oncogene. Its dysregulation is associated with the development and progression of various cancers, including colorectal cancer, glioblastoma, hepatocellular carcinoma, perihilar cholangiocarcinoma, gastric cancer, breast cancer, and lung cancer. SPRY4 is also involved in organ development and is associated with ischemic diseases. Further research is ongoing to understand the expression and function of SPRY4 in specific tumor microenvironments and its potential as a therapeutic target.

JPT2 Affects Trophoblast Functions and Macrophage Polarization and Metabolism, and Acts as a Potential Therapeutic Target for Recurrent Spontaneous Abortion

Recurrent spontaneous abortion (RSA) is a pregnancy-related condition with complex etiology. Trophoblast dysfunction and abnormal macrophage polarization and metabolism are associated with RSA; however, the underlying mechanisms remain unknown. Jupiter microtubule-associated homolog 2 (JPT2) is essential for calcium mobilization; however, its role in RSA remains unclear. In this study, it is found that the expression levels of JPT2, a nicotinic acid adenine dinucleotide phosphate-binding protein, are decreased in the villous tissues of patients with RSA and placental tissues of miscarried mice. Mechanistically, it is unexpectedly found that abnormal JPT2 expression regulates trophoblast function and thus involvement in RSA via c-Jun N-terminal kinase (JNK) signaling, but not via calcium mobilization. Specifically, on the one hand, JPT2 deficiency inhibits trophoblast adhesion, migration, and invasion by inhibiting the JNK/atypical chemokine receptor 3 axis. On the other hand, trophoblast JPT2 deficiency contributes to M1 macrophage polarization by promoting the accumulation of citrate and reactive oxygen species via inhibition of the JNK/interleukin-6 axis. Self-complementary adeno-associated virus 9-JPT2 treatment alleviates embryonic resorption in abortion-prone mice. In summary, this study reveals that JPT2 mediates the remodeling of the immune microenvironment at the maternal-fetal interface, suggesting its potential as a therapeutic target for RSA.

The regulated cell death at the maternal-fetal interface: beneficial or detrimental?

Regulated cell death (RCD) plays a fundamental role in placental development and tissue homeostasis. Placental development relies upon effective implantation and invasion of the maternal decidua by the trophoblast and an immune tolerant environment maintained by various cells at the maternal-fetal interface. Although cell death in the placenta can affect fetal development and even cause pregnancy-related diseases, accumulating evidence has revealed that several regulated cell death were found at the maternal-fetal interface under physiological or pathological conditions, the exact types of cell death and the precise molecular mechanisms remain elusive. In this review, we summarized the apoptosis, necroptosis and autophagy play both promoting and inhibiting roles in the differentiation, invasion of trophoblast, remodeling of the uterine spiral artery and decidualization, whereas ferroptosis and pyroptosis have adverse effects. RCD serves as a mode of communication between different cells to better maintain the maternal-fetal interface microenvironment. Maintaining the balance of RCD at the maternal-fetal interface is of utmost importance for the development of the placenta, establishment of an immune microenvironment, and prevention of pregnancy disorders. In addition, we also revealed an association between abnormal expression of key molecules in different types of RCD and pregnancy-related diseases, which may yield significant insights into the pathogenesis and treatment of pregnancy-related complications.

Research progress on the STAT signaling pathway in pregnancy and pregnancy-associated disorders

Signal transducer and activator of transcription (STAT) proteins, pivotal regulators of signaling cascades, undergo activation in response to the stimulation of cytokines and growth factors, and participate in biological processes, including inflammation, immune responses, cell proliferation, and differentiation. During the process of pregnancy, STAT signaling is involved in regulating embryonic implantation, endometrial decidualization, and establishing and maintaining maternal-fetal immune tolerance. Increasing evidence suggests that aberrant STAT signaling contributes to the occurrence and development of pregnancy disorders, including repeated implantation failure (RIF), preeclampsia (PE), recurrent spontaneous abortion (RSA), preterm birth (PTB) and gestational diabetes mellitus (GDM). Elucidating the molecular mechanisms of the STAT signaling pathway holds promise for further understanding the establishment and maintenance of normal pregnancy, and thereby providing potent targets and strategic avenues for the prevention and management of ailments associated with pregnancy. In this review, we summarized the roles of the STAT signaling pathway and its related regulatory function in embryonic implantation, endometrial decidualization, and maternal-fetal immune tolerance. In conclusion, in-depth research on the mechanism of the STAT signaling pathway not only enhances our understanding of normal pregnancy processes but also offers STAT-based therapeutic approaches to protect women from the burden of pregnancy-related disorders.

FKBP5 regulates trophoblast-macrophage crosstalk in recurrent spontaneous abortion through PI3K/AKT and NF-κB signaling pathways

FK506-binding protein 5 (FKBP5) contributes to many diseases; However, it remains unclear whether FKBP5 is relevant to recurrent spontaneous abortion (RSA) and the mechanisms by which it is involved in maternal-fetal immunological tolerance. Placental tissue was collected in women with normal pregnancy and RSA and examined for FKBP5 expression. Human trophoblast cell lines and THP-1-derived M0 macrophages were used to explore the role of FKBP5 in RSA and its mechanism. The role of FKBP5 on pregnancy outcomes was assessed using a mouse model of miscarriage. This study found that upregulation of FKBP5 at the placental interface is involved in the pathogenesis of RSA by depressing trophoblast function and promoting M1-type macrophage polarization. First, FKBP5 expression was upregulated in the villi of RSA, and FKBP5 regulated trophoblast function by inhibiting HAPLN1 expression through suppression of PI3K/AKT signaling. In addition, FKBP5 inhibited trophoblast IL-6 secretion by suppressing PI3K/AKT signaling, thereby promoting macrophage polarization toward the M1 phenotype. Meanwhile, FKBP5 was significantly elevated in decidual macrophages from patients with RSA and promoted M1 macrophage polarization via ROS/NF-κB signaling and further inhibited trophoblast function. Finally, FKBP5 inhibitors improved embryo resorption rate in miscarried mice. In conclusion, FKBP5 is essential in maintaining pregnancy and trophoblast-macrophage crosstalk in the maternal-fetal interface, which may be a potential target for diagnosing and treating RSA.

Interferon regulatory factor 1 (IRF1) inhibits lung endothelial regeneration following inflammation-induced acute lung injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a respiratory condition caused by severe endothelial barrier dysfunction within the lung. In ARDS, excessive inflammation, tissue edema, and immune cell influx prevents endothelial cell regeneration that is crucial in repairing the endothelial barrier. However, little is known about the molecular mechanism that underpin endothelial cell regeneration in ARDS.

METHODS

R-based bioinformatics tools were used to analyze microarray-derived transcription profiles in human lung microvascular endothelial cells (HLMVECs) subjected to non-treatment or lipopolysaccharide (LPS) exposure. We generated endothelial cell-specific interferon regulatory factor 1 (Irf1) knockout (Irf1EC-/-) and Irf1fl/fl control mice for use in an endotoxemic murine model of acute lung injury (ALI). In vitro studies (qPCR, immunoblotting, and ChIP-qPCR) were conducted in mouse lung endothelial cells (MLECs) and HLMVECs. Dual-luciferase promoter reporter assays were performed in HLMVECs.

RESULTS

Bioinformatics analyses identified IRF1 as a key up-regulated gene in HLMVECs post-LPS exposure. Endothelial-specific knockout of Irf1 in ALI mice resulted in enhanced regeneration of lung endothelium, while liposomal delivery of endothelial-specific Irf1 to wild-type ALI mice inhibited lung endothelial regeneration in a leukemia inhibitory factor (Lif)-dependent manner. Mechanistically, we demonstrated that LPS-induced Stat1Ser727 phosphorylation promotes Irf1 transactivation, resulting in downstream up-regulation of Lif that inhibits endothelial cell proliferation.

CONCLUSIONS

These results demonstrate the existence of a p-Stat1Ser727-Irf1-Lif axis that inhibits lung endothelial cell regeneration post-LPS injury. Thus, direct inhibition of IRF1 or LIF may be a promising strategy for enhancing endothelial cell regeneration and improving clinical outcomes in ARDS patients.

LDHA deficiency inhibits trophoblast proliferation via the PI3K/AKT/FOXO1/CyclinD1 signaling pathway in unexplained recurrent spontaneous abortion

Dysregulated trophoblast proliferation, invasion, and apoptosis may cause several pregnancy-associated complications, such as unexplained recurrent spontaneous abortion (URSA). Recent studies have shown that metabolic abnormalities, including glycolysis inhibition, may dysregulate trophoblast function, leading to URSA. However, the underlying mechanisms remain unclear. Herein, we found that lactate dehydrogenase A (LDHA), a key enzyme in glycolysis, was significantly reduced in the placental villus of URSA patients. The human trophoblast cell line HTR-8/SVneo was used to investigate the possible LDHA-mediated regulation of trophoblast function. LDHA knockdown in HTR-8/SVneo cells induced G0/G1 phase arrest and increased apoptosis, whereas LDHA overexpression reversed these effects. Next, RNA sequencing combined with Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that the PI3K/AKT signaling pathway is potentially affected by downstream genes of LDHA. Especially, we found that LDHA knockdown decreased the phosphorylation levels of PI3K, AKT, and FOXO1, resulting in a significant downregulation of CyclinD1. In addition, treatment with an AKT inhibitor or FOXO1 inhibitor also verified that the PI3K/AKT/FOXO1 signaling pathway influenced the gene expression of CyclinD1 in trophoblast. Moreover, p-AKT expression correlated positively with LDHA expression in syncytiotrophoblasts and extravillous trophoblasts in first-trimester villus. Collectively, this study revealed a new regulatory pathway for LDHA/PI3K/AKT/FOXO1/CyclinD1 in the trophoblast cell cycle and proliferation.

A prospective study comparing the inflammation-related cytokine and chemokine profile from the day of blastocyst transfer to 7 weeks of gestation between pregnancies that did or did not result in a miscarriage

The dynamics of maternal immunomodulation is essential in early pregnancy. In our previous study, successful implantation is characterized by a transient increase of pro-inflammatory cytokines followed by a switch to an anti-inflammatory state in peripheral blood around 3-6 days after embryo transfer (ET). In this study, we aimed to extend the time points to compare the cytokine and chemokine profiles between women who did or did not subsequently miscarry. We utilized precisely timed serum samples on the day of ET and 3, 6, 9, 16, 23 and 30 days after ET in women undergoing single blastocyst transfer. Our analysis revealed a significant alteration in cytokine profile after day ET+ 9 between the two groups. Regarding pro-inflammatory cytokine profile, there was a significant increase in IL-17 on days ET+ 16, + 23, and + 30 (50.60 ± 9.97 vs 37.09 ± 3.25, 53.20 ± 8.13 vs 36.51 ± 3.34, 57.06 ± 8.83 vs 33.04 ± 3.11 pg/mL), TNF-α on days ET+ 23 and + 30 (73.90 ± 12.42 vs 50.73 ± 3.55, 74.16 ± 12.46 vs 46.59 ± 3.21 pg/mL), IFN-γ on day ET+ 30 (69.52 ± 13.19 vs 42.28 ± 7.76 pg/mL) in women who miscarried compared to women who had a live birth. In contrast, the concentrations of anti-inflammatory cytokines IL-10 on days ET+ 23 and + 30 (26.23 ± 2.11 vs 38.30 ± 4.64, 23.77 ± 2.06 vs 39.16 ± 4.99 pg/mL) and TGF-β1 on day ET+ 30 (20.30 ± 1.25 vs 23.81 ± 0.88 ng/mL) were significantly decreased in women who miscarried compared to women who had a live birth. While for the chemokine profile, there was no significant alteration observed between the two groups across all the time points. These findings suggest that a sustained anti-inflammatory milieu is concomitant with the maintenance of early pregnancy, while the remarkable pro-inflammatory shift as early as day ET+ 16 in women who subsequently miscarried was observed before the diagnosis of miscarriage.

Expression pattern and clinical significance of microRNA-let-7a and IFN-gamma in placental tissue of patients with preeclampsia with severe features

OBJECTIVES

Preeclampsia with severe features (PECsf) is a common disease in pregnant women. let-7a and IFN-gamma (interferon-gamma) are involved in diagnosis and prognosis of preeclampsia. This study explored effects of let-7a and IFN-gamma on PECsf patients.

METHODS

The placental tissue of 21 PECsf, 19 preeclampsia without severe features (PEC), and 20 normal pregnant women were collected, and clinical data were recorded. let-7a and IFN-gamma expressions in placental tissue were detected. The correlation between let-7a/IFN-gamma expression and clinical indexes was analyzed. According to let-7a and IFN-gamma expressions, PECsf patients were assigned into Hlet-7a group (let-7a high expression group), Llet-7a group (let-7a low expression group), HIFN-gamma group (IFN-gamma high expression group) and LIFN-gamma group (IFN-gamma low expression group). The incidence of adverse prognosis was compared.

RESULTS

let-7a and IFN-gamma were highly expressed in placental tissue of preeclampsia patients, with significant differences between PEC and PECsf. The high expressions of let-7a and IFN-gamma were positively correlated with mean arterial pressure, lactate dehydrogenase, and 24 h urinary protein in placental tissues of PECsf patients. High let-7a and IFN-gamma expressions were correlated with adverse outcomes of PECsf.

CONCLUSIONS

High let-7a and IFN-gamma expressions were correlated with clinical features, and could be used as biomarkers for treatment and poor prognosis of PECsf.

Long non-coding RNA LINC01347 suppresses trophoblast cell migration, invasion and EMT by regulating miR-101-3p/PTEN/AKT axis

Recurrent miscarriage (RM) is one of the common complications of pregnancy, which is closely related to gene mutation. The profiling of non-coding RNAs showed that the expression level of long non-coding RNA LINC01347 (LINC01347) in the serum of patients with recurrent abortion was significantly increased, which could serve as a potential marker for early diagnosis. However, the biological functions of LINC01347 in the miscarriage remain to be elucidated. In this study, LINC01347 expression levels in HTR-8/SVneo cells and placenta samples were measured by RT-qPCR. The migration ability of HTR-8/SVneo cells was detected by wound-healing assay. Western blotting (WB) assay was conducted to measure E-cadherin, Vimentin, N-cadherin, PTEN, phospho-AKT(S473), phospho-AKT(T308) and AKT levels. Dual luciferase reporter assay and RNA pull-down analysis were performed to validate the molecular interactions. The results showed an upregulation of LINC01347 in the placenta samples of RM patients and HTR-8/SVneo cells. LINC01347 overexpression impaired the invasion and migration of trophoblast cells, while LINC01347 silencing promoted cell migration and invasion. LINC01347 level was also negatively correlated with the changes of epithelial-mesenchymal transition (EMT) markers in trophoblasts. We further demonstrated that miR-101-3p/PTEN/AKT axis played an important role in mediating the biological roles of LINC01347 in the invasion and migration of trophoblasts. In conclusion, our results revealed that LINC01347 suppresses the migratory ability and regulates the EMT processes in trophoblasts by regulating miR-101-3p/PTEN/AKT axis, suggesting that targeting LINC01347 may serve as a strategy to ameliorate RM.

First-Trimester Serum Cytokine Profile in Pregnancies Conceived After Assisted Reproductive Technology (ART) With Subsequent Pregnancy-Induced Hypertension

Pregnancy-induced hypertension (PIH) is one of the most common pregnancy complications that seriously affects the mother and fetus. The incidence of PIH is higher in pregnancies conceived after assisted reproductive technology (ART) than in spontaneous pregnancies; thus, exploring potential serum biomarkers before PIH onset is of great significance for effective early prediction and prevention of PIH in the ART population. Cytokines are involved in the inflammatory response and immune regulation, which play an essential role in the pathogenesis of PIH. A description of the cytokine profile in the first trimester of pregnancy could help identify new diagnostic tools and develop targeted therapies for PIH in the ART population. The concentrations of classical predictive markers for PIH and another 48 cytokines were measured in the first-trimester pregnancy serum samples from 33 PIH patients and 33 matched normotensive controls (NC), both of whom conceived after ART treatment. The measured values were compared and analyzed between NC and PIH, followed by comprehensive bioinformatic analysis and logistic regression analysis. There was no significant difference in classical predictive markers, including Activin A, PlGF, sFLT1 (VEGFR), and sFLT1/PlGF, between the PIH and NC groups (P > 0.05), while 29 cytokines were significantly lower in the PIH group than in the NC group (P < 0.05). Logistic regression analysis revealed that 17 cytokines (IL-2Rα, M-CSF, IL-6, IL-2, β-NGF, IL-7, IL-12 (p70), SCF, IL-10, IL-9, MIG, GM-CSF, LIF, IL-1α, MCP-3, IL-4, and HGF) in the first-trimester pregnancy serum were significantly negatively correlated with the subsequent onset of PIH. With the top 3 cytokines (IL-7, MIG, and SCF) of receiver operating characteristic (ROC) analysis, we constructed an efficient multifactor combined detection and prediction model for PIH in ART pregnancy. Classical early predictors for hypertensive disorder complicating pregnancy cannot distinguish PIH from their normal peers in ART pregnancy. In comparison, the description of the cytokine profile in the first trimester of pregnancy enables us to distinguish high-risk ART pregnancy for PIH, permitting enough time for PIH prevention therapy. The cytokine profile we described also provides immunological insight into the further mechanistic exploration of PIH.

Environmental BPDE induced human trophoblast cell apoptosis by up-regulating lnc-HZ01/p53 positive feedback loop

Human trophoblast cell apoptosis may induce miscarriage. Trophoblast cells are sensitive to environmental BaP-7,8-dihydrodiol-9,10-epoxide (BPDE). However, how BPDE induces human trophoblast cell apoptosis is still largely elusive. In this work, we used BPDE-treated human trophoblast cells and villous tissues collected from recurrent miscarriage and health control groups to explore the underlying mechanism of BPDE-induced human trophoblast cell apoptosis. Continued with our recent work, we found that lncRNA HZ01 (lnc-HZ01) could induce human trophoblast cell apoptosis. In mechanism, lnc-HZ01 up-regulated p53 expression level by suppressing its MDM2-mediated proteasomal degradation. Meanwhile, we found that p53 acted as lnc-HZ01 transcription factor and promoted lnc-HZ01 transcription. Thus, lnc-HZ01 and p53 composed a positive feedback loop in human trophoblast cells. In normal trophoblast cells, relatively low levels of lnc-HZ01 and p53 suppressed p53/caspase-3 apoptosis pathway, giving normal pregnancy. Upon BPDE exposure, BPDE up-regulated the expression levels of lnc-HZ01 and p53, triggered this positive feedback loop, activated the p53/caspase-3 apoptosis pathway, and then induced miscarriage. Collectively, we discovered new mechanism by which lnc-HZ01 regulated BPDE-induced human trophoblast cell apoptosis, providing scientific basis for the diagnosis and treatment of unexplained recurrent miscarriage.

An imbalance of the IL-33/ST2-AXL-efferocytosis axis induces pregnancy loss through metabolic reprogramming of decidual macrophages

During embryo implantation, apoptosis is inevitable. These apoptotic cells (ACs) are removed by efferocytosis, in which macrophages are filled with a metabolite load nearly equal to the phagocyte itself. A timely question pertains to the relationship between efferocytosis-related metabolism and the immune behavior of decidual macrophages (dMΦs) and its effect on pregnancy outcome. Here, we report positive feedback of IL-33/ST2-AXL-efferocytosis leading to pregnancy failure through metabolic reprogramming of dMΦs. We compared the serum levels of IL-33 and sST2, along with IL-33 and ST2, efferocytosis and metabolism of dMΦs, from patients with normal pregnancies and unexplained recurrent pregnancy loss (RPL). We revealed disruption of the IL-33/ST2 axis, increased apoptotic cells and elevated efferocytosis of dMΦs from patients with RPL. The dMΦs that engulfed many apoptotic cells secreted more sST2 and less TGF-β, which polarized dMΦs toward the M1 phenotype. Moreover, the elevated sST2 biased the efferocytosis-related metabolism of RPL dMΦs toward oxidative phosphorylation and exacerbated the disruption of the IL-33/ST2 signaling pathway. Metabolic disorders also lead to dysfunction of efferocytosis, resulting in more uncleared apoptotic cells and secondary necrosis. We also screened the efferocytotic molecule AXL regulated by IL-33/ST2. This positive feedback axis of IL-33/ST2-AXL-efferocytosis led to pregnancy failure. IL-33 knockout mice demonstrated poor pregnancy outcomes, and exogenous supplementation with mouse IL-33 reduced the embryo losses. These findings highlight a new etiological mechanism whereby dMΦs leverage immunometabolism for homeostasis of the microenvironment at the maternal-fetal interface.

Screening and identification of microRNAs from plasma-derived extracellular vesicles (EVs) of Dazu black goat (Capra hircus) in early pregnant stages

Previous studies have shown that extracellular vesicles (EVs) containing proteins, lipids, nucleic acids and other biological components exist in all kinds of body fluids. EVs, as an intercellular communication carrier, regulate the functions of its target cells by transporting biomacromolecules between cells. In this study, a total of six female Dazu black goats were divided into NP group (NP, non-pregnant group) and P30 (P30, 30-day pregnant group). The goats in NP group (n = 3) were in estrus, but failed to fertilize; the other goats in P30 group (n = 3) were fertilized by natural mating. Firstly, goats plasma-derived EVs were isolated using ultracentrifugation. Secondly, EVs were identified by transmission electron microscope (TEM), dynamic light scattering (DLS), and by testing its markers (CD9 and CD63) using west blotting in NP and P30 groups, respectively. Thirdly, EVs related miRNAs were sequenced and analyzed by bioinformatics method. Data shows that miR-31-5p, miR-137-3p, novel_miR_1355, novel_miR_734 and novel_miR_736 exclusively were expressed in P30 group. Their target genes were significantly enriched in the axon guidance, the Notch signaling pathway, the Wnt signaling pathway, tight junction and the Hippo signaling pathway. And miRNA-mRNA interactive network analysis reveals potential regulatory functions of miRNAs for goat during early pregnancy. These findings provided theretical references for studying the regulation of plasma-derived EVs between the fetal and placental development, and these candidate miRNAs identified might be as markers for diagnosis of goat early pregnancy.

Crosstalk Between Trophoblasts and Decidual Immune Cells: The Cornerstone of Maternal-Fetal Immunotolerance

The success of pregnancy relies on the fine adjustment of the maternal immune system to tolerate the allogeneic fetus. Trophoblasts carrying paternal antigens are the only fetal-derived cells that come into direct contact with the maternal immune cells at the maternal–fetal interface. The crosstalk between trophoblasts and decidual immune cells (DICs) via cell–cell direct interaction and soluble factors such as chemokines and cytokines is a core event contributing to the unique immunotolerant microenvironment. Abnormal trophoblasts–DICs crosstalk can lead to dysregulated immune situations, which is well known to be a potential cause of a series of pregnancy complications including recurrent spontaneous abortion (RSA), which is the most common one. Immunotherapy has been applied to RSA. However, its development has been far less rapid or mature than that of cancer immunotherapy. Elucidating the mechanism of maternal–fetal immune tolerance, the theoretical basis for RSA immunotherapy, not only helps to understand the establishment and maintenance of normal pregnancy but also provides new therapeutic strategies and promotes the progress of immunotherapy against pregnancy-related diseases caused by disrupted immunotolerance. In this review, we focus on recent progress in the maternal–fetal immune tolerance mediated by trophoblasts–DICs crosstalk and clinical application of immunotherapy in RSA. Advancement in this area will further accelerate the basic research and clinical transformation of reproductive immunity and tumor immunity.

Increased expression of IFN-γ in preeclampsia impairs human trophoblast invasion via a SOCS1/JAK/STAT1 feedback loop

The weakening of extravillous trophoblast (EVT) invasion results in shallow placenta implantation. In HTR8/SVneo cells, IFN-γ can activate STAT1 and reduce cell invasion, and suppressor of cytokine signaling (SOCS) is an important negative regulatory protein in the Janus kinase (JAK)/STAT activator pathway and has a negative feedback function on JAK/STAT1. The aim of the present study was to elucidate how SOCS1 feedback regulates JAK/STAT1 and affects EVT cell invasion, which in turn affects the development of preeclampsia (PE). MTT and Annexin V/phosphatidylserine (PS) assays were performed to evaluate the viability and apoptosis of HTR8/SVneo cells treated with IFN-γ, respectively. Wound healing and invasion assays were also conducted to measure the migratory and invasive abilities of IFN-γ-treated HTR8/SVneo cells. The mRNA and protein expression levels of genes were detected using reverse transcription-quantitative PCR and western blot analysis. Small interfering RNA knockdown of SOCS1 was used to verify the role of feedback regulation in the IFN-γ-activated JAK/STAT1 signaling pathway. IFN-γ can inhibit HTR8/SVneo migration and invasion, and promote apoptosis by increasing the expression of phosphorylated (p)-JAK, p-STAT1 and caspase3, and reducing the expression of platelet-derived growth factor receptor A and Ezrin. Furthermore, SOCS1 may negatively regulate JAK/STAT1 and affect HTR-8/SVneo invasiveness. Evaluation of clinical samples demonstrated that the expression levels of SOCS1 and IFN-γ were higher in patients with PE compared with the healthy group. Collectively, the present results indicated that IFN-γ reduced the invasion of HTR-8/SVneo cells by activating JAK/STAT1, concurrently leading to an increase in SOCS1, which negatively regulates JAK/STAT1 and eliminates the pro-inflammatory effects of IFN-γ, thus forming a feedback loop.