Extravillous Trophoblast Cells Research Articles

Preeclampsia is Associated With Reduced ISG15 Levels Impairing Extravillous Trophoblast Invasion.

Among several interleukin (IL)-6 family members, only IL-6 and IL-11 require a gp130 protein homodimer for intracellular signaling due to lack of intracellular signaling domain in the IL-6 receptor (IL-6R) and IL-11R. We previously reported enhanced decidual IL-6 and IL-11 levels at the maternal-fetal interface with significantly higher peri-membranous IL-6 immunostaining in adjacent interstitial trophoblasts in preeclampsia (PE) vs. gestational age (GA)-matched controls. This led us to hypothesize that competitive binding of these cytokines to the gp130 impairs extravillous trophoblast (EVT) differentiation, proliferation and/or invasion. Using global microarray analysis, the current study identified inhibition of interferon-stimulated gene 15 (ISG15) as the only gene affected by both IL-6 plus IL-11 vs. control or IL-6 or IL-11 treatment of primary human cytotrophoblast cultures. ISG15 immunostaining was specific to EVTs among other trophoblast types in the first and third trimester placental specimens, and significantly lower ISG15 levels were observed in EVT from PE vs. GA-matched control placentae (p = 0.006). Induction of primary trophoblastic stem cell cultures toward EVT linage increased ISG15 mRNA levels by 7.8-fold (p = 0.004). ISG15 silencing in HTR8/SVneo cultures, a first trimester EVT cell line, inhibited invasion, proliferation, expression of ITGB1 (a cell migration receptor) and filamentous actin while increasing expression of ITGB4 (a receptor for hemi-desmosomal adhesion). Moreover, ISG15 silencing further enhanced levels of IL-1β-induced pro-inflammatory cytokines (CXCL8, IL-6 and CCL2) in HTR8/SVneo cells. Collectively, these results indicate that ISG15 acts as a critical regulator of EVT morphology and function and that diminished ISG15 expression is associated with PE, potentially mediating reduced interstitial trophoblast invasion and enhancing local inflammation at the maternal-fetal interface. Thus, agents inducing ISG15 expression may provide a novel therapeutic approach in PE.

Dynamic Changes in Uterine NK Cell Subset Frequency and Function Over the Menstrual Cycle and Pregnancy.

Uterine natural killer cells (uNK) play an important role in promoting successful pregnancy by regulating trophoblast invasion and spiral artery remodelling in the first trimester. Recently, single-cell RNA sequencing (scRNAseq) on first-trimester decidua showed that uNK can be divided into three subsets, which may have different roles in pregnancy. Here we present an integration of previously published scRNAseq datasets, together with novel flow cytometry data to interrogate the frequency, phenotype, and function of uNK1–3 in seven stages of the reproductive cycle (menstrual, proliferative, secretory phases of the menstrual cycle; first, second, and third trimester; and postpartum). We found that uNK1 and uNK2 peak in the first trimester, but by the third trimester, the majority of uNK are uNK3. All three subsets are most able to degranulate and produce cytokines during the secretory phase of the menstrual cycle and express KIR2D molecules, which allow them to interact with HLA-C expressed by placental extravillous trophoblast cells, at the highest frequency during the first trimester. Taken together, our findings suggest that uNK are particularly active and able to interact with placental cells at the time of implantation and that uNK1 and uNK2 may be particularly involved in these processes. Our findings are the first to establish how uNK frequency and function change dynamically across the healthy reproductive cycle. This serves as a platform from which the relationship between uNK function and impaired implantation and placentation can be investigated. This will have important implications for the study of subfertility, recurrent miscarriage, pre-eclampsia, and pre-term labour.

GDF-11 promotes human trophoblast cell invasion by increasing ID2-mediated MMP2 expression

BackgroundGrowth differentiation factor-11 (GDF-11), also known as bone morphogenetic protein-11, belongs to the transforming growth factor-beta superfamily. GDF-11 was first identified as an important regulator during embryonic development. Increasing evidence has demonstrated that GDF-11 regulates the development of various organs and its aberrant expressions are associated with the risk of cardiovascular diseases and cancers. Extravillous trophoblast (EVT) cells invasion is a critical event for placenta development and needs to be finely regulated. However, to date, the biological function of GDF-11 in the human EVT cells remains unknown.MethodsHTR-8/SVneo, a human EVT cell line, and primary cultures of human EVT cells were used to examine the effect of GDF-11 on matrix metalloproteinase 2 (MMP2) expression. Matrigel-coated transwell invasion assay was used to examine cell invasiveness. A series of in vitro experiments were applied to explore the underlying mechanisms that mediate the effect of GDF-11 on MMP2 expression and cell invasion.ResultsTreatment with GDF-11 stimulates MMP2 expression, in the HTR-8/SVneo and primary human EVT cells. Using a pharmacological inhibitor and siRNA-mediated knockdown approaches, our results demonstrated that the stimulatory effect of GDF-11 on MMP2 expression was mediated by the ALK4/5-SMAD2/3 signaling pathways. In addition, the expression of inhibitor of DNA-binding protein 2 (ID2) was upregulated by GDF-11 and that was required for the GDF-11-stimulated MMP2 expression and EVT cell invasion.ConclusionsThese findings discover a new biological function and underlying molecular mechanisms of GDF-11 in the regulation of human EVT cell invasion.Ede8tEoyGya1QPPVVUV7JYVideo

SERPINA5 may promote the development of preeclampsia by disruption of the uPA/uPAR pathway

Preeclampsia (PE) is the leading cause of maternal and fetal morbidity or mortality but lacks reliable methods for early diagnosis. In a previous study, serum SERPINA5 levels were higher in women with PE before the clinical manifestation of the disease. This study aimed to evaluate the efficacy of SERPINA5 in predicting PE and investigate its role in trophoblast cell biology. A multicenter, 2-stage observational case-control study was performed to develop and validate an early predictive PE model based on SERPINA5, maternal characteristics, and inflammatory factors. To further understand the relationship between SERPINA5 and PE, SERPINA5 was overexpressed or knocked down in extravillous trophoblast cells (EVT) and a pregnant rat model. After development and initial validation, a model that combined SERPINA5 and inflammatory factors had a high predictive ability for PE before 20 weeks gestation with an AUC of 0.90 (95% CI 0.83-0.96). It also demonstrated that SERPINA5 inhibited primary EVT cell invasion by disrupting the urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor (uPA/uPAR) pathway, in turn, is involved in the development of PE. In vivo experiments also proved that overexpression of SERPINA5 induced a PE-like syndrome (hypertension and proteinuria) in pregnant rats. Therefore, serum SERPINA5 is a promising early biomarker of PE, suggesting that it may be involved in placental development through its action on the uPA/uPAR system prior to the clinical manifestation of PE.

Endometrial HLA-F expression is influenced by genotypes and correlates differently with immune cell infiltration in IVF and recurrent implantation failure patients.

Is human leukocyte antigen (HLA)-F protein expressed in mid-secretory endometrium, and are its expression levels influenced by HLA-F gene polymorphisms and correlated with the abundance of uterine natural killer (uNK) cells and anti-inflammatory M2 macrophages? HLA-F protein is expressed in mid-secretory endometrium, and levels are correlated with immune cell infiltration, plasma progesterone concentrations and HLA-F single-nucleotide polymorphisms (SNPs), however, women experiencing recurrent implantation failure (RIF) show differences when compared to women attending their first IVF treatment. The immunomodulatory HLA class Ib molecules HLA-G and HLA-F are expressed on the extravillous trophoblast cells and interact with receptors on maternal immune cells. Little is known regarding HLA-F expression in endometrial stroma and HLA-F function; furthermore, HLA-F and HLA-G SNP genotypes and haplotypes have been correlated with differences in time-to-pregnancy. Primary endometrial stromal cell (ESC) cultures (n = 5) were established from endometrial biopsies from women attending IVF treatment at a fertility clinic. Basic HLA-F and HLA-G protein expression by the ESCs were investigated. A prospective controlled cohort study was performed including 85 women with a history of RIF and 36 control women beginning their first fertility treatment and with no history of RIF. In some analyses, the RIF group was divided into unknown cause, male infertility, female infertility, and both female and male infertility. Endometrial biopsies and blood samples were obtained the day equivalent to embryo transfer in a hormone-substituted cycle. HLA protein expression by ESCs was characterized using flow cytometry and western blot. In the cohort study, the specific immune markers HLA-F and HLA-G, CD56 and CD16 (NK cells), CD163 (M2 macrophages), FOXP3 (regulatory T cells) and CD138 (plasma cells) were analysed by immunohistochemistry and a digital image analysis system in endometrial biopsies. Endometrial receptivity was assessed by an endometrial receptivity array test (the ERA® test). Endometrial biopsies were examined according to modified Noyes' criteria. SNPs at the HLA-F gene and HLA-G haplotypes were determined. HLA-F protein is expressed in the endometrium at the time of implantation. Furthermore, the HLA-F protein levels were different according to the womeńs HLA-F SNP genotypes and diplotypes, which have previously been correlated with differences in time-to-pregnancy. Endometrial HLA-F was positively correlated with anti-inflammatory CD163+ M2 macrophage infiltration and CD56+ uNK cell abundance for the entire cohort. However, this was not the case for CD56+ in the female infertility RIF subgroup. HLA-F levels in the endometrial stroma were negatively correlated with plasma progesterone concentrations in the RIF subgroup with known female infertility. Conversely, HLA-F and progesterone were positively correlated in the RIF subgroup with infertility of the male partner and no infertility diagnosis of the woman indicating interconnections between progesterone, HLA-F and immune cell infiltration. Glandular sHLA-G expression was also positively correlated with uNK cell abundance in the RIF subgroup with no female infertility but negatively correlated in the RIF subgroup with a female infertility diagnosis. Immunohistochemistry analyses of endometrial biopsies and DNA sequencing of HLA genes. Data will be shared upon reasonable request to the corresponding author. The control group of women attending their first IVF treatment had an anticipated good prognosis but was not proven fertile. A significant age difference between the RIF group and the IVF group reflects the longer treatment period for women with a history of RIF. The standardization of hormonal endometrial preparation, which allowed consistent timing of endometrial and blood sampling, might be a strength because a more uniform hormonal background may more clearly show an influence on the immune marker profile and HLA class Ib levels in the endometrium by other factors, for example genetic polymorphisms. However, the immune marker profile might be different during a normal cycle. The findings further highlight the importance of HLA-F and HLA-G at the implantation site and in early pregnancy for pregnancy success. Diagnostic measures and modulation of the complex interactions between HLA class Ib molecules, maternal immune cells and hormonal factors may have potential to improve fertility treatment. This work was supported by the Region Zealand Health Sciences Research Foundation and the Zealand University Hospital through the ReproHealth Research Consortium ZUH. The authors declared there are no conflicts of interest.

Narrative review of the relationship between the maternal-fetal interface immune tolerance and the onset of preeclampsia.

Background and ObjectiveThe establishment of maternal-fetal interface immune tolerance is essential for successful pregnancy. Studies have shown that spontaneous abortion, recurrent abortion, and fetal growth restriction are related to maternal-fetal interface immune dysfunction. Preeclampsia is an idiopathic condition related to pregnancy which manifests as hypertension, proteinuria, and other target organ damage after 20 weeks of gestation. Although the etiology of preeclampsia is still unknown, its pathogenesis is thought to be related to genetics, environment, and metabolism. In recent years, more and more studies have been conducted on the mechanism of immune tolerance at the maternal-fetal interface and the relationship between immune dysregulation and the pathogenesis of preeclampsia. This paper summarizes the latest studies on this topic in order to find new insights into the pathogenesis of preeclampsia and make a reflection on clinical diagnosis and treatment in different phenotype of preeclampsia.MethodsThe research and latest progress published from 2000 to December 2021 on the relationship between maternal-fetal interface immune tolerance and preeclampsia were broadly retrieved and researched using PubMed and Web of Science databases.Key Content and FindingsThe mechanism of natural killer cells (NK cells) and macrophages at the maternal-fetal interface in immune tolerance, as well as their cytotoxicity and cytokine secretion dysfunction, may be related to the pathogenesis of preeclampsia. The expression of nonclassical type I human leukocyte antigen (HLA) on extravillous trophoblast (EVT) cell were down-regulated in decidua of preeclampsia, which may induce increase EVT death caused by activating of cytotoxic NK cell. In addition, genetic polymorphism of nonclassical type I HLA on the EVT cell membrane may be related to the pathogenesis of preeclampsia, although this is likely to be a combination of 3 nonclassical type I HLA genotypes and requires sequencing to verify.ConclusionsWe demonstrated how the maternal-fetal interface immune dysfunction contribute to the pathogenesis of preeclampsia, further study and clinical trial based on this theory of pathogenesis may reveal new immune treatment method of preeclampsia.

Hypoxia regulates fibrosis-related genes via histone lactylation in the placentas of patients with preeclampsia.

Histone lactylation, a novel epigenetic modification induced by hypoxia and lactate, plays an important role in regulating gene expression. However, the role of histone lactylation in the pathogenesis of preeclampsia remains unknown. Placentas from preeclamptic patients and control pregnant women were collected for protein immunoassay to detect the expression level of histone lactylation, and two trophoblast cell lines were used to simulate the effect of histone lactylation on genes. We found that lactate and histone lactylation levels were increased in preeclamptic placentas. In vitro, hypoxia was demonstrated to induce histone lactylation by promoting the production of lactate in human-trophoblast-derived cell line (HTR-8/SVneo) and human first-trimester extravillous trophoblast cell line (TEV-1) cells. In addition, 152 genes were found to be upregulated by both hypoxia exposure and sodium l-lactate treatment in HTR-8/SVneo cells. These genes were mainly enriched in the pathways including the response to hypoxia, cell migration and focal adhesion. Among the 152 genes, nine were upregulated in preeclamptic placentas. Most noteworthy, two upregulated fibrosis-related genes, FN1 and SERPINE1, were promoted by hypoxia through histone lactylation mediated by the production of lactate. The present study demonstrated the elevated levels of histone lactylation in preeclamptic placentas and identified fibrosis-related genes that were promoted by histone lactylation induced by hypoxia in trophoblast cells, which provides novel insights into the mechanism of placental dysfunction in preeclampsia.

Krüppel-like factor 6 participates in extravillous trophoblast cell differentiation and its expression is reduced in abnormally invasive placenta.

Trophoblast cell differentiation is of paramount importance for successful pregnancy. Krüppel-like factor 6 (KLF6), a transcription factor with diverse roles in cell physiology and tumor biology, is required for trophoblast differentiation through the syncytial pathway. Herein, we demonstrate that extravillous trophoblast (EVT) cell migration and mesenchymal phenotype are increased upon KLF6 downregulation or the expression of a deletion mutant lacking its transcriptional regulatory domain (KΔac). Raman spectroscopy revealed molecular modifications compatible with increased differentiation in cells stably expressing the KΔac mutant. Moreover, abnormally invasive placenta showed lower KLF6 immunostaining compared with the normal placenta. Thus, impaired KLF6 expression or function stimulates EVT migration and differentiation in vitro and may contribute to the physiopathology of the abnormally invasive placenta.

Uterine NK cell functions at maternal-fetal interface†.

During pregnancy, maternal decidual tissue interacts with fetal trophoblasts. They constitute the maternal-fetal interface responsible for supplying nutrition to the fetus. Uterine natural killer (uNK) cells are the most abundant immune cells at the maternal-fetal interface during early pregnancy and play critical roles throughout pregnancy. This review provides current knowledge about the functions of uNK cells. uNK cells have been shown to facilitate remodeling of the spiral artery, control the invasion of extravillous trophoblast (EVT) cells, contribute to the induction and maintenance of immune tolerance, protect against pathogen infection, and promote fetal development. Pregnancy-trained memory of uNK cells improves subsequent pregnancy outcomes. In addition, this review describes the distinct functions of three uNK cell subsets: CD27-CD11b-, CD27+, and CD27-CD11b+ uNK cells.

A genome-wide CRISPR-Cas9 knockout screen identifies essential and growth-restricting genes in human trophoblast stem cells

The recent derivation of human trophoblast stem cells (hTSCs) provides a scalable in vitro model system of human placental development, but the molecular regulators of hTSC identity have not been systematically explored thus far. Here, we utilize a genome-wide CRISPR-Cas9 knockout screen to comprehensively identify essential and growth-restricting genes in hTSCs. By cross-referencing our data to those from similar genetic screens performed in other cell types, as well as gene expression data from early human embryos, we define hTSC-specific and -enriched regulators. These include both well-established and previously uncharacterized trophoblast regulators, such as ARID3A, GATA2, and TEAD1 (essential), and GCM1, PTPN14, and TET2 (growth-restricting). Integrated analysis of chromatin accessibility, gene expression, and genome-wide location data reveals that the transcription factor TEAD1 regulates the expression of many trophoblast regulators in hTSCs. In the absence of TEAD1, hTSCs fail to complete faithful differentiation into extravillous trophoblast (EVT) cells and instead show a bias towards syncytiotrophoblast (STB) differentiation, thus indicating that this transcription factor safeguards the bipotent lineage potential of hTSCs. Overall, our study provides a valuable resource for dissecting the molecular regulation of human placental development and diseases.

Caffeic acid protects human trophoblast HTR-8/SVneo cells from H2O2-induced oxidative stress and genotoxicity

Caffeic acid is highlighted as one of the major phenolic compounds present in foods with known antioxidant activity. This phenolic is among commonly consumed substances in everyday diet of pregnant women. However, there is not enough information on its effects during pregnancy, especially the most vulnerable early stage. Extravillous trophoblast cells are specific cells of the placenta that come in direct contact with maternal uterine tissue.Through this study we investigated the cytoprotective effects of caffeic acid on H2O2-induced oxidative damage in first trimester extravillous trophoblast cell line HTR-8/SVneo. Investigated concentrations (1–100 μM) of caffeic acid showed neither cytotoxic nor genotoxic effects on HTR-8/SVneo cells. The treatment with caffeic acid 100 μM significantly increased the percentage of cells in G2/M phase of the cell cycle, compared to non-treated cells. Pretreatment with caffeic acid (10 and 100 μM) attenuated oxidative DNA damage significantly, reduced cytotoxicity, protein and lipid peroxidation, and restored antioxidant capacity in trophoblast cells following H2O2 exposure. This beneficial outcome is probably mediated by the augmentation of GSH and effective ROS scavenging by caffeic acid. These promising results require further investigations to reveal the additional mechanisms/pathways and confirmation through studies in vivo.

Low-dose aspirin prevents LPS-induced preeclampsia-like phenotype via AQP-1 and the MAPK/ERK 1/2 pathway.

Clinical studies suggest that early pregnancy is the critical window for the prevention of preeclampsia by low-dose aspirin (LDA). Abnormal extravillous trophoblast (EVT) cell invasion and spiral artery remodeling during early placentation have been observed in preeclampsia cases. Thus, we hypothesized LDA prevents preeclampsia by mitigating EVT migration/invasion and spiral artery remodeling dysfunction. A single systemic lipopolysaccharide (LPS) (1μg/kg) injection was administrated in pregnant mice at e14.5 to induce a preeclampsia-like pregnant mouse model. We administered LDA (2.5μg/g body weight/day) and observed the effects on LPS-induced preeclampsia-like symptoms by examining the placental histology, protein expression, EVT invasion, and spiral artery remodeling. In human EVT cell line, HTR-8/SVneo, we investigated cell invasion and migration by matrigel and wound healing assays, respectively. Signaling pathways were surveyed using inhibitors, siRNA transfections, and Western blot. LDA treatment significantly reversed the preeclampsia-like phenotype induced by LPS, as observed by decreases in hypertension, proteinuria, and fetal growth retardation. The numbers of pathological lesions, including excessive extracellular matrix deposition, endotheliosis, and collapsed glomerular capillaries in kidneys, were significantly lower in the LDA+LPS vs. the LPS group. LDA pretreatment eliminated placental lesions, including calcification, edema, and narrowed uterine spiral arteries and reduced aquaporin-1 (AQP-1) protein expression. In HTR-8/SVneo cells, LDA rescued the decreased cell migration and invasion induced by LPS. The phosphorylation of ERK1/2 was up-regulated and AQP-1 expression was decreased by LPS, which were reversed by LDA treatments. The effects of LDA were inhibited when AQP-1 expression was downregulated by siRNA transfection. This study provides new evidence that supports the use of LDA for the prevention of preeclampsia and suggests that the effects of LDA are mediated through a novel mechanism of a water channel, AQP-1, and MAPK/ERK 1/2 signaling.

Insights into Early-Pregnancy Mechanisms: Mast Cells and Chymase CMA1 Shape the Phenotype and Modulate the Functionality of Human Trophoblast Cells, Vascular Smooth-Muscle Cells and Endothelial Cells.

Spiral-artery (SA) remodeling is a fundamental process during pregnancy that involves the action of cells of the initial vessel, such as vascular smooth-muscle cells (VSMCs) and endothelial cells, but also maternal immune cells and fetal extravillous trophoblast cells (EVTs). Mast cells (MCs), and specifically chymase-expressing cells, have been identified as key to a sufficient SA-remodeling process in vivo. However, the mechanisms are still unclear. The purpose of this study is to evaluate the effects of the MC line HMC-1 and recombinant human chymase (rhuCMA1) on human primary uterine vascular smooth-muscle cells (HUtSMCs), a human trophoblast cell line (HTR8/SV-neo), and human umbilical-vein endothelial cells (HUVEC) in vitro. Both HMC-1 and rhuCMA1 stimulated migration, proliferation, and changed protein expression in HUtSMCs. HMC-1 increased proliferation, migration, and changed gene expression of HTR8/SVneo cells, while rhuCMA treatment led to increased migration and decreased expression of tissue inhibitors of matrix metalloproteinases. Additionally, rhuCMA1 enhanced endothelial-cell-tube formation. Collectively, we identified possible mechanisms by which MCs/rhuCMA1 promote SA remodeling. Our findings are relevant to the understanding of this crucial step in pregnancy and thus of the dysregulated pathways that can lead to pregnancy complications such as fetal growth restriction and preeclampsia.

Lysine (K)-specific demethylase 5C regulates the incidence of severe preeclampsia by adjusting the expression of bone morphogenetic protein-7

ABSTRACT This study aimed to investigate the roles of the lysine (K)-specific demethylase 5C (KDM5C)–bone morphogenetic protein-7 (BMP-7) signaling pathway in the pathogenesis of severe preeclampsia (sPE). A total of 180 pregnant patients were enrolled in the study and classified into three groups: an early-onset sPE group (EOsPE) (n = 60), a late-onset sPE group (LOsPE) (n = 60), and a control group (normal pregnancy; n = 60). The messenger RNA (mRNA) and protein expression levels of bone morphogenetic protein receptor II (BMPRII), BMP-7, and KDM5C were detected in placenta samples from the two sPE groups, and their sites were evaluated using immunohistochemistry (IHC). The sPE groups showed an increased KDM5C mRNA expression, and the EOsPE group showed a decreased BMP-7 and BMPRII mRNA expression compared with the LOsPE group. However, contradictory results were discovered in terms of protein expression. Immunostaining of KDM5C, BMP-7, and BMPRII was observed in villous trophoblast and extravillous trophoblast cells. Compared with the control group, the staining intensity of KDM5C in the placental tissue trophoblast cell nucleus and vascular endothelial cells of the sPE groups was weaker, while that of BMP-7 and BMPRII was stronger, and the staining intensity was more subjective in the LOsPE group. Consistent findings were obtained by IHC and Western blot analysis. KDM5C nuclear-cytoplasmic translocation may regulate sPE through BMP-7 and its receptors. The KDM5C–BMP-7 signaling pathway may also lead to less invasion and increased apoptosis of the trophoblast cells, which is involved in the pathogenesis of sPE.

Reduced volumetric parameters of the placenta and extravillous trophoblastic cells in complicated pregnancies may lead to intrauterine growth restriction and small for gestational age birth.

We undertook this study to determine quantitative changes of the placenta, focusing on extravillous trophoblastic cells (EVTs) in pregnancies with intrauterine growth restriction (IUGR) and small for gestational age (SGA) compared to the control group. Placentas from pregnancies complicated with SGA-IUGR (n=10) and control group (n=10) were obtained after cesarean surgery and evaluated using stereological assays after routine tissue processing and Masson's trichrome staining. Mann-Whitney U-test was employed, and the level of statistical significance was set at p <0.05. Our results showed that the volumetric parameters, including the total volume and volume density of chorionic villi, intervillous spaces, blood vessels in chorionic villi, and syncytiotrophoblast, decreased significantly in the SGA-IUGR group compared to control placentas (p <0.05). Also, total volume, number of EVTs, volume, the diameter of cytoplasm, and diameter of the nucleus in these cells were significantly lower in the SGA-IUGR group (p <0.05). In addition, the nucleus to cytoplasm ratio of EVTs was also higher in the SGA-IUGR group (p <0.05). There are several significant histological and stereological differences in the placenta, particularly its EVTs from the SGA-IUGR group compared to the control group. It seems that histological changes in the placental tissues could be helpful for the retrospective explanations of pregnancy complications.

Hypoxia and inflammation conditions differentially affect the expression of tissue transglutaminase spliced variants and functional properties of extravillous trophoblast cells.

Persistent hypoxia and inflammation beyond early pregnancy are involved in a bad outcome because of defective trophoblast invasiveness. Tissue transglutaminase (TG2) coregulates several cell functions. An aberrant expression and/or transamidation activity could contribute to placental dysfunction. The first-trimester trophoblast cell line (Swan-71) was used to study TG2 expression and cell functions in the absence or presence of inflammatory cytokines (TNF-α, IL-1β) or chemical hypoxia (CoCl2 ). We analyzed The concentration of cytokines in the supernatant by ELISA; Cell migration by scratch assay; NF-κB activation by detection of nuclear p65 by immunofluorescence or flow cytometry using a Swan-71 NF-κB-hrGFP reporter cell line. Tissue transglutaminase expression was analyzed by immunoblot and confocal microscopy. Expression of spliced mRNA variants of tissue transglutaminase was analyzed by RT-PCR. Transamidation activity was assessed by flow cytometry using 5-(biotinamido)-pentylamine substrate. Chemical hypoxia and TGase inhibition, but not inflammatory stimuli, decreased Swan-71 migration. IL-6 production was also decreased by chemical hypoxia, but increased by inflammation. Intracellular TGase activity was increased by all stimuli, but NF-κB activation was observed only in the presence of proinflammatory cytokines. TG2 expression was decreased by CoCl2 and TNF-α. Translocation of TG2 and p65 to nuclei was observed only with TNF-α, without colocalization. Differential relative expression of spliced variants of mRNA was observed between CoCl2 and inflammatory stimuli. The observed decrease in total TG2 expression and relative increase in short variants under hypoxia conditions could contribute to impaired trophoblast invasion and impact on pregnancy outcome.

The effects of oil sands process-affected water naphthenic acid fraction components on GDF15 secretion in extravillous trophoblast cells

Exposure to compounds present in petroleum and wastewaters from oil and gas extraction sites in the Alberta Oil Sands Region can impair reproductive health. It has been established that acid extractable organics found in oil sands process-affected water (OSPW) such as naphthenic acids (NA-fraction components; NAFC) can adversely affect reproductive outcomes. We have shown that NAFC exposure results in a significant upregulation of GDF15 in placental trophoblasts, a cellular stress marker known to be involved in human embryonic development and necessary for the maintenance of pregnancy. However, little is known regarding the mechanism(s) underlying NAFC-induced increases in GDF15 production during early placentation. The goal of this study was to examine the effects of NAFC exposure on the regulation of critical transcription factors of GDF15 in extravillous trophoblast cells. Of these transcription factors, inflammatory mediators including prostaglandins have been reported to inhibit proliferation and migration of trophoblast cells in vitro. Hence, the secondary goal of this study was to determine whether inflammation mediated through prostaglandin production is critical to GDF15 secretion. HTR-8/SVneo cells were exposed to an NAFC for 6 and 24 h to assess the expression of key transcriptional regulators, GDF15 secretion, and prostaglandin (PGE2) output. Treatment with NAFC (125 mg/L only) significantly increased GDF15 expression and secretion in association with upregulation of the transcription factors KLF4, EGR1, ATF3 and TP53. Similarly, PTGS2 (i.e. COX2) expression and PGE2 output were significantly increased at the same concentration. However, co-treatment with a COX2 selective antagonist (SC236) only partially blocked the NAFC-induced increase in PGE2 output and did not block GDF15 expression or secretion. These findings suggest that while NAFC may affect GDF15 production, it is not exclusively a result of prostaglandin-mediated inflammation. This study provides new insights into the mechanisms by which NAFC may adversely affect placental trophoblast cell function in mammals.

Diminished trophoblast differentiation in early onset preeclampsia.

The mechanism by which human cytotrophoblast cells (CTB) differentiate into extravillous trophoblast cells (EVT) is an epithelial-mesenchymal transition (EMT). Polarized CTB, anchored in an epithelial layer, are transformed into motile, non-polar EVT which invade the uterus. Our previous research has shown that over gestation, invasive first trimester EVT are converted to a non-invasive phenotype showing a reduced degree of EMT. We hypothesized that in an under-invasion pathology, such as early onset preeclampsia, third trimester EVT would display a less advanced EMT profile than controls. The goal of this study was to determine whether expression of EMT-associated genes in the EVT of early onset preeclamptics shows a less mesenchymal, more epithelial phenotype compared to control pregnancies. Measures of preeclamptic CTB and EVT gene expression, using highly purified cells from third trimester, early onset preeclamptics and gestational-age matched controls, showed clear evidence of a phenotypic pattern characteristic of an EMT. Comparison of preeclamptic EVT to gestational-age matched, control EVT demonstrated multiple changes in gene expression, including changes in well-known EMT gene markers, indicative of a more limited EMT. These changes are not explained by differences in the preeclamptic CTB precursors. In this first study of purified third trimester EVT, we show that the pattern of gene expression corresponding to EMT-associated differentiation is diminished in early onset preeclampsia. This provides a mechanistic framework for many of the molecular changes observed in preeclampsia and presents an opportunity for detailed studies of the pathways regulating the aberrant EMT and for potential biomarkers of the process.

Characterization of chloride intracellular channel 4 in the regulation of human trophoblast function.

Proper placentation requires well controlled extravillous trophoblast cell (EVT) migration and invasion. Transforming growth factor β (TGFβ) signaling has been well characterized as negatively regulating EVT migration and invasion. CLIC4 is an enhancer of TGFβ signaling, however CLIC4's function in placentation and its association to placental TGFβ signaling is unknown. Here we aimed to investigate the role of CLIC4 on trophoblast cell function and its relationship to TGFβ signaling. CLIC4 was immunolocalized in human placenta throughout gestation and the first trimester decidua. siRNA was used to knockdown CLIC4 in a human trophoblast cell line (HTR8/SVneo) to reveal functional consequences of CLIC4 loss on cell adhesion, proliferation, migration and invasion via xCELLigence. qPCR was used to identify downstream targets of CLIC4 in HTR8/SVNeo cells. CLIC4 was widely expressed in the syncytiotrophoblast, cytotrophoblast and decidual cells across all trimesters of pregnancy with no significant difference in staining intensity in the different cellular compartments both across gestation and between compartments. Using immunofluorescent co-localization of CLIC4 and EVT marker HLA-G, we confirmed that CLIC4 localized to the cytoplasm of cell column EVTs in the first trimester decidua and nuclei of some EVTs that invaded in the decidua. Knockdown of CLIC4 in HTR8/SVneo cells significantly elevated cell adhesion, migration and invasion. Analysis of TGFβ signaling downstream targets identified that CDH2 and BAMBI expression were significantly increased after CLIC4 knockdown in HTR8/SVneo cells. Our data support an inhibitory role for CLIC4 in regulating trophoblast migration and invasion, likely acting in part via BAMBI and CDH2.

Contribution of vascular smooth muscle cell apoptosis to spiral artery remodeling in early human pregnancy.

Uterine spiral artery remodeling is one of the key maternal adaptations of pregnancy, allowing delivery of the large volumes of maternal blood required for both placental and fetal growth. Failure of this process is associated with obstetric complications including preeclampsia, fetal growth restriction and miscarriage. Spiral artery remodeling is characterized by loss of the musculoelastic wall which is replaced by fibrinoid and intramural extravillous trophoblast cells (EVT). In recent years attention has focused on the initial stages of spiral artery remodeling which include separation of the vascular smooth muscle cells (VSMCs) and their phenotypic switch to a more synthetic phenotype, facilitating their migration away from the vessel wall. However, less is known about the final fate of the VSMCs. In vitro studies suggested that EVT could induce VSMC apoptosis, though VSMC apoptosis is not seen within the wall of the spiral arteries undergoing remodeling. However, apoptotic VSMCs have been observed amongst those cells which had migrated away from the vessel wall. This review article gives a brief overview of the current state of knowledge of the processes involved in spiral artery remodeling, and then concentrates on the mechanisms involved in VSMC apoptosis, drawing on knowledge from other vascular beds.