Oxidative stress-induced C/EBPβ inhibits β-catenin signaling molecule involving in the pathology of preeclampsia

INTRODUCTION

Oxidative stress-induced trophoblast cell dysfunction is a major pathology in preeclampsia (PE). Recently, CCAAT/enhancer binding protein beta (C/EBPβ) has been investigated as a tumor suppressor that participates in tumor invasion. However, the function of C/EBPβ in trophoblast cells remains unknown. Our study was designed to detect the expression of C/EBPβ in the preeclamptic placenta and to identify the underlying mechanisms of oxidative stress.

METHODS

Human placental tissues with PE were collected. The expression of C/EBPβ and β-catenin were detected. Human first trimester extravillous trophoblast cell (HTR8/SVneo) line exposed to hypoxia/reoxygenation (H/R) was employed as an oxidative stress model in vitro to investigate the effects of C/EBPβ on invasion and the expression of β-catenin. Moreover, first trimester-derived placental villous explants were used to verify the effects of C/EBPβ and β-catenin in placentation.

RESULTS

In preeclamptic placentas, C/EBPβ was overexpressed and β-catenin was decreased. In addition, C/EBPβ was found to have increased expression in H/R-treated HTR8/SVneo cells and villous explants. C/EBPβ knockdown and β-catenin activation could significantly promote the invasion of HTR8/SVneo cells, enhance the outgrowth and migration in villous explants and inhibit the excessive generation of intracellular ROS. These findings might be related to the increased activities of MMP-2/9 and the decreased expression of TIMP-1/2. Meanwhile, C/EBPβ knockdown remarkably increased the expression of β-catenin.

DISCUSSION

We hypothesize that the oxidative stress-induced overexpression of C/EBPβ might influence the activity of MMPs by regulating the Wnt/β-catenin signaling pathway to affect the invasion of trophoblast cells, which then participate in the pathogenesis of preeclampsia.

Trophoblast expression of the minor histocompatibility antigen HA-1 is regulated by oxygen and is increased in placentas from preeclamptic women

INTRODUCTION

Maternal T-cells reactive towards paternally inherited fetal minor histocompatibility antigens are expanded during pregnancy. Placental trophoblast cells express at least four fetal antigens, including human minor histocompatibility antigen 1 (HA-1). We investigated oxygen as a potential regulator of HA-1 and whether HA-1 expression is altered in preeclamptic placentas.

METHODS

Expression and regulation of HA-1 mRNA and protein were examined by qRT-PCR and immunohistochemistry, using first, second, and third trimester placentas, first trimester placental explant cultures, and term purified cytotrophoblast cells. Low oxygen conditions were achieved by varying ambient oxygen, and were mimicked using cobalt chloride. HA-1 mRNA and protein expression levels were evaluated in preeclamptic and control placentas.

RESULTS

HA-1 protein expression was higher in the syncytiotrophoblast of first trimester as compared to second trimester and term placentas (P<0.01). HA-1 mRNA was increased in cobalt chloride-treated placental explants and purified cytotrophoblast cells (P = 0.04 and P<0.01, respectively) and in purified cytotrophoblast cells cultured under 2% as compared to 8% and 21% oxygen (P<0.01). HA-1 mRNA expression in preeclamptic vs. control placentas was increased 3.3-fold (P = 0.015). HA-1 protein expression was increased in syncytial nuclear aggregates and the syncytiotrophoblast of preeclamptic vs. control placentas (P = 0.02 and 0.03, respectively).

DISCUSSION

Placental HA-1 expression is regulated by oxygen and is increased in the syncytial nuclear aggregates and syncytiotrophoblast of preeclamptic as compared to control placentas. Increased HA-1 expression, combined with increased preeclamptic syncytiotrophoblast deportation, provides a novel potential mechanism for exposure of the maternal immune system to increased fetal antigenic load during preeclampsia.

ERBB2 gene amplification increases during the transition of proximal EGFR(+) to distal HLA-G(+) first trimester cell column trophoblasts

INTRODUCTION

Although, DNA copy-number alterations (CNAs) have been well documented in a number of adverse phenotypic conditions, accumulating data suggest that CNAs also occur during physiological processes. Interestingly, extravillous trophoblasts induce the expression of the transforming, proto-oncogene ERBB2, which is frequently amplified in human cancer. However, no data are available to address whether trophoblast-related ERBB2 expression might also be linked to genomic amplification.

METHODS

Dual color silver as well as fluorescence in situ hybridization analyses were carried out to evaluate frequency and degree of ERBB2 gene and chromosome 17 copy numbers in first trimester placental cell columns and isolated trophoblasts. Proliferative EGFR(+) and differentiated HLA-G(+) trophoblasts were identified or separated by means of in situ immunofluorescence co-stainings and magnetic beads cell isolation, respectively.

RESULTS

ERBB2 gene amplification is detected in approximately 40% of isolated HLA-G(+) trophoblasts. Although already detectable in EGFR(+) cells, the percentage and extent of ERBB2 amplification was markedly increased in HLA-G(+) trophoblasts in situ and after isolation. Accordingly, HLA-G(+) trophoblasts highly express ERBB2 on protein level. Finally, ERBB2 copy number variations occur independently of aneuploidy as the majority of ERBB2 amplifying cells were cytogenetically diploid for chromosome 17.

DISCUSSION

ERBB2 gene amplification is a frequent event during EVT differentiation. This finding challenges the long standing paradigm, which associates gene amplification with pathological conditions and further supports recent evidences suggesting that CNAs are a normal feature of developmental processes.

Changes in Functional Activity of JEG-3 Trophoblast Cell Line in the Presence of Factors Secreted by Placenta

BACKGROUND AND AIMS

Cells in the maternal-fetal interface secrete cytokines that regulate proliferation, migration, and trophoblast invasion during the first trimester of pregnancy and the limitation of these processes during the third trimester. The aim of the study was to evaluate the influence of factors secreted by human placenta during the first and third trimester of pregnancy on cytokine receptor expression and proliferative and migratory activity of JEG-3 trophoblast cells.

METHODS

The research was conducted using the explant conditioned media of placentas obtained from healthy women with elective termination of pregnancy at 9-11 weeks and placentas of women whose pregnancy progressed without complications at 38-39 weeks. Assessment of surface molecule expression was performed using FACS Canto II flow cytometer (BD, USA). The proliferative activity of JEG-3 trophoblast cells was evaluated by dyeing with crystal violet vital dye. The migration activity of JEG-3 was evaluated using 24-well insert plates with polycarbonate inserts (pore size 8 microns).

RESULTS

Expression of CD116, CD118, CD119, IFNγ-R2, CD120b, CD183, CD192, CD295, EGFR, and TGFβ-R2 on JEG-3 was higher when the cells were incubated in the presence of the third trimester placental factors in comparison with the first trimester placental factors. Factors secreted by the placenta during the third trimester of pregnancy had more pronounced stimulatory effect on the proliferation and migration of trophoblast in comparison with baseline levels and with the effect of the first trimester placental factors.

CONCLUSIONS

The findings suggest that the behavior of trophoblasts in vitro might not be representative of in vivo behavior in the absence of additional local factors that influence the trophoblast in vivo.

N-myc downstream-regulated gene 1 (NDRG1) mediates pomegranate juice protection from apoptosis in hypoxic BeWo cells but not in primary human trophoblasts

INTRODUCTION

N-Myc downstream-regulated gene 1 (NDRG1) expression is increased in placentas of human pregnancies with intrauterine growth restriction and in hypoxic cultured primary trophoblasts. We previously showed that elevated NDRG1 decreases trophoblast apoptosis induced by hypoxia. Separately, we found that pomegranate juice (PJ) decreases cell death induced by hypoxia in trophoblasts. Here, we test the hypothesis that PJ protects trophoblasts from hypoxia-induced apoptosis by modulating NDRG1 expression.

METHODS

Quantitative rtPCR was used to investigate the effects of PJ treatment on mRNA levels of 22 candidate genes involved in apoptosis, oxidative stress, and differentiation in trophoblasts. Western blotting and immunofluorescence were used to analyze NDRG1 protein levels. siRNA-mediated NDRG1 knockdown was used to investigate the role of NDRG1 in response to PJ in hypoxic BeWo choriocarcinoma cells and hypoxic cultured primary human trophoblasts.

RESULTS

The mRNA levels of eight genes were altered, with NDRG1 showing the largest response to PJ and thus, we pursued the role of NDRG1 here. PJ significantly increased NDRG1 protein expression in primary trophoblasts and in BeWo cells. Knockdown of NDRG1 in hypoxic BeWo cells in the presence of PJ yielded increased apoptosis. In contrast, knockdown of NDRG1 in hypoxic primary trophoblasts in the presence of PJ did not increase apoptosis.

DISCUSSION

We conclude that the PJ-mediated decrease in cell death in hypoxia is partially mediated by NDRG1 in BeWo cells but not in primary trophoblasts. The disparate effects of NDRG1 between BeWo cells and primary trophoblasts indicate caution is required when extrapolating from results obtained with cell lines to primary trophoblasts.

Effect of the maternal-fetal interface immunoregulation on the occurrence of intrahepatic cholestasis of pregnancy

Maternal immune tolerance of the fetus is indispensable for a healthy pregnancy. Currently, the study of the immune microenvironment of the maternal-fetal interface has been a heated topic in reproductive immunology research. More and more studies show that the immune imbalance in the maternal-fetal interface plays a very important role in the incidence of intrahepatic cholestasis of pregnancy (ICP). However, the precise etiology and mechanism of immune imbalance in the occurrence of ICP is still unknown. In order to clarify the potential immunologic mechanisms of ICP, this review summarizes the recent studies of the decidual immunology microenvironment and the potential immunologic mechanisms related to the development of ICP.

Placenta expresses anti-Müllerian hormone and its receptor: Sex-related difference in fetal membranes

INTRODUCTION

Anti-Müllerian hormone (AMH) is a member of the transforming growth factor-β superfamily, playing a role in sexual differentiation and recruitment. Since a correlation exists between AMH serum levels in cord blood and fetal sex, the present study aimed to identify mRNA and protein expression of AMH and AMHRII in placenta and fetal membranes according to fetal sex.

METHODS

Placenta and fetal membranes samples (n = 40) were collected from women with singleton uncomplicated pregnancies at term. Identification of AMH protein in placenta and fetal membranes was carried out by immunohistochemistry and AMH and AMHRII protein localization by immunofluorescence, while mRNA expression was assessed by quantitative real-time PCR.

RESULT

AMH and AMHRII mRNAs were expressed by placenta and fetal membranes at term, without any significant difference between males and females. Placental immunostaining showed a syncytial localization of AMH without sex-related differences; while fetal membranes immunostaining was significantly more intense in male than in female fetuses (p < 0,01). Immunofluorescence showed an intense co-localization of AMH and AMHRII in placenta and fetal membranes.

DISCUSSION

The present study for the first time demonstrated that human placenta and fetal membranes expresses and co-localizes AMH and AMHRII. Although no sex-related difference was found for the mRNA expression both in placenta and fetal membranes, a most intense staining for AMH in male fetal membranes supports AMH as a gender specific hormone.

Hedgehog signaling through GLI1 and GLI2 is required for epithelial-mesenchymal transition in human trophoblasts

BACKGROUND

Epithelial to mesenchymal transition (EMT) is critical for human placental development, trophoblastic differentiation, and pregnancy-associated diseases. Here, we investigated the effects of hedgehog (HH) signaling on EMT in human trophoblasts, and further explored the underlying mechanism.

METHODS

Human primary cytotrophoblasts and trophoblast-like JEG-3 cells were used as in vitro models. Quantitative real-time RT-PCR and Western blot analysis were performed to examine mRNA and protein levels, respectively. Lentiviruses expressing short hairpin RNA were used to knock down the target genes. Reporter assays and chromatin immunoprecipitation were performed to determine the transactivity. Cell migration, invasion and colony formation were accessed by wound healing, Matrigel-coated transwell, and colony formation assays, respectively.

RESULTS

Activation of HH signaling induced the transdifferentiation of cytotrophoblasts and trophoblast-like JEG-3 cells from epithelial to mesenchymal phenotypes, exhibiting the decreases in E-Cadherin expression as well as the increases in vimentin expression, invasion, migration and colony formation. Knockdown of GLI1 and GLI2 but not GLI3 attenuated HH-induced transdifferentiation, whereas GLI1 was responsible for the expression of HH-induced key EMT regulators including Snail1, Slug, and Twist, and both GLI1 and GLI2 acted directly as transcriptional repressor of CDH1 gene encoding E-Cadherin.

CONCLUSION

HH through GLI1 and GLI2 acts as critical signals in supporting the physiological function of mature placenta.

GENERAL SIGNIFICANCE

HH signaling through GLI1 and GLI2 could be required for the maintenance of human pregnancy.

Paracrine communication modulates production of Wnt antagonists and COX1-mediated prostaglandins in a decidual-trophoblast co-culture model

Wnt signalling has important roles in decidualisation, implantation and placentation. We investigated the role of decidua-trophoblast communication and Wnt signalling in the placenta using a co-culture model. Expression of a wide range of Wnt-related genes was observed in both decidual and trophoblast cells using PCR array, with remarkably similar expression profiles. Co-culture induced altered expression of several Wnt-related proteins, with the Wnt inhibitors sFPR4 and DKK1 being among the most differentially expressed genes. Media concentrations of sFRP4 and DKK1 were increased with co-culture, coincident with a decrease in canonical Wnt signalling activity. Expression of PTGS1 mRNA and COX1 protein was also increased with co-culture as were media PGE2 concentrations; these changes were replicated by addition of exogenous DKK1 and sFRP4. Collectively, these data suggest that paracrine interactions between decidua and trophoblast stimulate Wnt antagonist secretion leading to increased placental prostaglandin production. This may be important for implantation and placental function.

The invasive phenotype of placenta accreta extravillous trophoblasts associates with loss of E-cadherin

INTRODUCTION

Epithelial-to-mesenchymal transition (EMT) is a process of molecular and phenotypic epithelial cell alteration promoting invasiveness. Loss of E-cadherin (E-CAD), a transmembrane protein involved in cell adhesion, is a marker of EMT. Proteolysis into N- and C-terminus fragments by ADAM10 and presenilin-1 (PSEN-1) generates soluble (sE-CAD) and transcriptionally active forms. We studied the protein expression patterns of E-CAD in the serum and placenta of women with histologically-confirmed over-invasive placentation.

METHODS

The patterns of expression and levels of sE-CAD were analyzed by Western blot, immunoassay, and immunoprecipitation. Tissue immunostaining for E-CAD, cytokeratin-7 (epithelial marker), vimentin (mesenchymal marker), ADAM10, PSEN-1 and β-catenin expression were investigated in parallel.

RESULTS

N-terminus cleaved 80 kDa sE-CAD fragments were present in serum of pregnant women with gestational age regulation of the circulatory levels. Women with advanced trophoblast invasion did not display circulatory levels of sE-CAD different from those of women with normal placentation. Histologically, extravillous trophoblasts (EVT) closer to the placental-myometrial interface demonstrated less E-CAD staining than those found deeper in the myometrium. These cells expressed both vimentin and cytokeratin, an additional feature of EMT. EVT of placentas with advanced invasion displayed intracellular E-CAD C-terminus immunoreactivity predominating over that of the extracellular N-terminus, a pattern consistent with preferential PSEN-1 processing.

DISCUSSION

Local processing of E-CAD may be an important molecular mechanism controlling the invasive phenotype of accreta EVT.

Effects of maternal diabetes on trophoblast cells

Diabetes mellitus (DM) is a health condition characterized by hyperglycemia over a prolonged period. There are three main types of DM: DM type 1 (DM1), DM2 and gestational DM (GDM). Maternal diabetes, which includes the occurrence of DM1 and DM2 during pregnancy or GDM, increases the occurrence of gesttional complications and adverse fetal outcomes. The hyperglycemic intrauterine environment affects not only the fetus but also the placental development and function in humans and experimental rodents. The underlying mechanisms are still unclear, but some evidence indicates alterations in trophoblast proliferation, apoptosis and cell cycle control in diabetes. A proper coordination of trophoblast proliferation, differentiation and invasion is required for placental development. Initially, increased expression of proliferative markers in junctional and labyrinth zones of rat placentas and villous cytotrophoblast, syncytiotrophoblast, stromal cells and fetal endothelial cells in human placentas is reported among diabetics. Moreover, reduced apoptotic index and expression of some apoptotic genes are described in placentas of GDM women. In addition, cell cycle regulators including cyclins and cyclin-dependent kinase inhibitors seem to be affected by the hyperglycemic environment. More studies are necessary to check the balance between proliferation, apoptosis and differentiation in trophoblast cells during maternal diabetes.

Viperin is induced following toll-like receptor 3 (TLR3) ligation and has a virus-responsive function in human trophoblast cells

INTRODUCTION

Viperin, a virus-inducible antiviral protein, has been reported to inhibit the replication of a variety of viruses. However, its expression and function in trophoblast cells remains unclear. Toll-like receptor 3 (TLR3) is a key component of the innate immune system that recognizes viral double-stranded RNA and triggers immune reactions by producing type I interferon. We hypothesized that viperin inhibits the replication of human cytomegalovirus (HCMV) in trophoblast cells.

METHODS

In situ examinations of viperin expression was conducted in the human first-trimester placenta by immunohistochemical staining. Using a human trophoblast cell culture system, we studied the effect of TLR-3 ligation on viperin expression by treating trophoblasts with polyinosinic-polycytidylic acid [Poly (I: C)] (a synthetic double-stranded RNA, which mimics viral RNA). Viperin mRNA and protein expression were evaluated by real-time PCR and Western blot analysis. In a HCMV infected Swan 71 cell model, HCMV immediate early 1 (IE1) protein mRNA expression was evaluated by real-time PCR after viperin RNA interference.

RESULTS

Viperin was localized in trophoblast cells. Poly (I: C) induced viperin expression in a dosage and time-dependent manner. Blocking of TLR3 signaling by neutralizing antibody against IFN-β abolished the stimulation of viperin expression. After HCMV infection, expression of viperin mRNA and protein was unregulated. HCMV IE1 mRNA expression was significantly inhibited by viperin RNA interference.

DISCUSSION

Viperin is a virus-responsive protein that is constitutively expressed in human trophoblast cells. However, contrary to our hypothesis, viperin facilitates HCMV replication post infection.

Dose effect of gestational ethanol exposure on placentation and fetal growth

INTRODUCTION

Prenatal ethanol exposure compromises fetal growth by impairing placentation. Invasive trophoblastic cells, which mediate placentation, express the insulin-IGF regulated gene, aspartyl-asparaginyl β-hydroxylase (ASPH), which has a critical role in cell motility and invasion. The aims of this study were to characterize effects of ethanol on trophoblastic cell motility, and assess ethanol dose-dependent impairments in placentation and fetal development.

METHODS

Pregnant Long Evans dams were fed with isocaloric liquid diets containing 0%, 8%, 18% or 37% ethanol (caloric content) from gestation day (GD) 6 to GD18. Fetal development, placental morphology, density of invasive trophoblasts at the mesometrial triangle, as well as placental and mesometrial ASPH and Notch-1 protein expression were evaluated. Directional motility of control and ethanol-exposed HTR-8/SVneo cells was assessed by ATP Luminescence-Based assay.

RESULTS

Severity of fetal growth impairment correlated with increasing doses of ethanol. Ethanol exposure produced dose-dependent alterations in branching morphogenesis at the labyrinthine zone, and inhibited physiological transformation of maternal arteries. ASPH and Notch-1 protein expression levels were reduced, corresponding with impairments in placentation.

DISCUSSION

Prenatal ethanol exposure compromises fetal growth and placentation in a dose-responsive manner. Ethanol's adverse effects on placental development are mediated by: (1) altered branching morphogenesis in labyrinthine zone; (2) suppression of invasive trophoblastic precursor cells; and (3) inhibition of trophoblastic cell adhesion and motility, corresponding with reduced ASPH and Notch-1 protein expression.

IFPA meeting 2014 workshop report: Animal models to study pregnancy pathologies; new approaches to study human placental exposure to xenobiotics; biomarkers of pregnancy pathologies; placental genetics and epigenetics; the placenta and stillbirth and fetal growth restriction

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2014 there were six themed workshops, five of which are summarized in this report. These workshops related to various aspects of placental biology but collectively covered areas of animal models, xenobiotics, pathological biomarkers, genetics and epigenetics, and stillbirth and fetal growth restriction.

Activin/nodal signaling switches the terminal fate of human embryonic stem cell-derived trophoblasts

Human embryonic stem cells (hESCs) have been routinely treated with bone morphogenetic protein and/or inhibitors of activin/nodal signaling to obtain cells that express trophoblast markers. Trophoblasts can terminally differentiate to either extravillous trophoblasts or syncytiotrophoblasts. The signaling pathways that govern the terminal fate of these trophoblasts are not understood. We show that activin/nodal signaling switches the terminal fate of these hESC-derived trophoblasts. Inhibition of activin/nodal signaling leads to formation of extravillous trophoblast, whereas loss of activin/nodal inhibition leads to the formation of syncytiotrophoblasts. Also, the ability of hESCs to form bona fide trophoblasts has been intensely debated. We have examined hESC-derived trophoblasts in the light of stringent criteria that were proposed recently, such as hypomethylation of the ELF5-2b promoter region and down-regulation of HLA class I antigens. We report that trophoblasts that possess these properties can indeed be obtained from hESCs.

Expression and Distribution of Calcium-Binding Protein S100P in Human Placenta during Pregnancy

Background

S100P is a member of the S100 family of calcium-binding proteins, and it participates in pathophysiological events, such as tumor growth and invasion. Based on the striking similarities between trophoblast cells and tumor cells with regard to proliferative and invasive properties, we raised the question of whether and how S100P expresses in trophoblast cells during development. This study aimed to investigate the expression pattern of S100P in the human placenta during pregnancy development.

Materials and Methods

In this experimental study, we collected 16 first-trimester placental tissues, 10 second-trimester placental tissues, and 12 term placentas. The mRNA expression levels of S100P were detected by reverse-transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR, the protein expression levels were detected by western blot, and the localization of S100P was measured by immunohistochemical staining. The values obtained from PCR and western blot analysis were expressed as the mean ± SD. Levene’s test was used to test equal variances, and one-way analysis of variance (ANOVA) was used to evaluate differences between groups.

Results

Protein and mRNA expression of S100P could be detected in placenta during pregnancy, with minor higher levels in first-trimester (p>0.05). Immunohistochemical staining revealed that S100P protein was strongly expressed in syncytiotrophoblasts, and moderate expression was detected in villous cytotrophoblasts and cytotrophoblast columns. The S100P protein was localized to both cytoplasm and nuclei in syncytiotrophoblasts, while it only existed in the cytoplasm of cytotrophoblasts.

Conclusion

S100P was strongly detected in human placenta during pregnancy. The specific expression and distribution of S100P in human placenta throughout gestation suggested that S100P function might vary with its location in the placenta.

Review: Annexin-A5 and cell membrane repair

Annexins are soluble proteins that bind to biological membranes containing negatively charged phospholipids, principally phosphatidylserine, in a Ca(2+)-dependent manner. Annexin-A5 (AnxA5), the smallest member of the annexin family, presents unique properties of membrane binding and self-assembly into ordered two-dimensional (2D) arrays on membrane surfaces. We have previously reported that AnxA5 plays a central role in the machinery of membrane repair by enabling rapid resealing of plasma membrane disruption in murine perivascular cells. AnxA5 promotes membrane repair via the formation of a protective 2D bandage at membrane damaged site. Here, we review current knowledge on cell membrane repair and present recent findings on the role of AnxA5 in membrane resealing of human trophoblasts.

Histopathology in the placentae of women with antiphospholipid antibodies: A systematic review of the literature

BACKGROUND

Antiphospholipid antibodies (aPLs) are a heterogenous group of autoantibodies associated with recurrent miscarriage, stillbirth, foetal growth restriction and premature birth. The cause of obstetric morbidity in women with aPLs is not completely understood. Workers have attempted to understand the role of aPLs in obstetric morbidity by investigating the histopathology of placentae from aPL-positive women. However, it is unclear from these diverse, and at times contradictory reports what histopathological lesions are common in the placentae of women with aPLs. This systematic review was undertaken to generate a complete picture of the placental features associated with aPLs in an attempt to understand the pathological processes that occur in pregnancies affected by aPLs.

METHODS

Pubmed, Scopus, Web of Science and Embase were searched on the 27th November 2014 using the keywords "placenta" OR "trophoblast" AND "antiphospholipid antibody" OR "antiphospholipid antibody syndrome". Records that were relevant and eligible were qualitatively assessed and given a score out of 24.

RESULTS

Of the 1112 records that were retrieved from the systematic search, 34 records were eligible for review, and were qualitatively scored. Of the 44 histopathological features that were reported in 580 placentae from aPL-positive women, six features appeared to be more common in the placentae of aPL-positive women compared to control women, including: placental infarction, impaired spiral artery remodelling, decidual inflammation, increased syncytial knots, decreased vasculosyncytial membranes and the deposition of complement split product C4d.

CONCLUSION

Based on the evidence in this systematic review, a human placental aPL fingerprint has been proposed. The diversity of the human placental aPL fingerprint suggests that multiple pathological processes may occur in pregnancies affected by aPL.

Annexin-A5 promotes membrane resealing in human trophoblasts

Annexin-A5 (AnxA5) is the smallest member of the annexins, a group of soluble proteins that bind to membranes containing negatively-charged phospholipids, principally phosphatidylserine, in a Ca(2+)-dependent manner. AnxA5 presents unique properties of binding and self-assembling on membrane surfaces, forming highly ordered two-dimensional (2D) arrays. We showed previously that AnxA5 plays a central role in the machinery of cell membrane repair of murine perivascular cells, promoting the resealing of membrane damages via the formation of 2D protein arrays at membrane disrupted sites and preventing the extension of membrane ruptures. As the placenta is one of the richest source of AnxA5 in humans, we investigated whether AnxA5 was involved in membrane repair in this organ. We addressed this question at the level of human trophoblasts, either mononucleated cytotrophoblasts or multinucleated syncytiotrophoblasts, in choriocarcinoma cells and primary trophoblasts. Using established procedure of laser irradiation and fluorescence microscopy, we observed that both human cytotrophoblasts and syncytiotrophoblasts repair efficiently a μm²-size disruption. Compared to wild-type cells, AnxA5-deficient trophoblasts exhibit severe defect of membrane repair. Through specifically binding to the disrupted site as early as a few seconds after membrane wounding, AnxA5 promotes membrane resealing of injured human trophoblasts. In addition, we observed that a large membrane area containing the disrupted site was released in the extracellular milieu. We propose mechanisms ensuring membrane resealing and subsequent lesion removal in human trophoblasts. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.

The physiologic and therapeutic role of heparin in implantation and placentation

Implantation, trophoblast development and placentation are crucial processes in the establishment and development of normal pregnancy. Abnormalities of these processes can lead to pregnancy complications known as the great obstetrical syndromes: preeclampsia, intrauterine growth restriction, fetal demise, premature prelabor rupture of membranes, preterm labor, and recurrent pregnancy loss. There is mounting evidence regarding the physiological and therapeutic role of heparins in the establishment of normal gestation and as a modality for treatment and prevention of pregnancy complications. In this review, we will summarize the properties and the physiological contributions of heparins to the success of implantation, placentation and normal pregnancy.

Progesterone Inhibits Leptin-Induced Invasiveness of BeWo Cells

BACKGROUND

This study investigated the roles of progesterone and leptin in placenta invasion, which is closely related to pregnancy prognosis. We examined the effects of leptin and progesterone on the invasion of BeWo cells, a human trophoblastic cell line, and the effect of concurrent treatment.

METHODS

Cells were treated with leptin (0, 5, 50, or 500 ng/mL) or progesterone (0, 2, 20, or 200 µM) and cultured in an invasion assay. Cells treated with 500 ng/mL leptin were also treated with progesterone (0, 2, 20, or 200 µM) in the invasion assay for 48 h. The number of cells that invaded the lower surface was counted in five randomly chosen fields using a light microscope with a 200× objective. The mRNA expression levels of MMP-9, TIMP1, TIMP2, and E-cadherin were detected by semi-quantitative PCR.

RESULTS

Invasion of BeWo cells was promoted by leptin and influenced by both leptin concentration and treatment duration. Invasion was most effective at 500 ng/mL leptin and 48 h culture. Leptin-induced invasiveness was suppressed by progesterone in a dose-dependent manner. Leptin significantly decreased the expression levels of TIMP1 and E-cadherin, whereas progesterone significantly decreased expression of MMP-9 and significantly increased levels of TIMP1, TIMP2, and E-cadherin.

CONCLUSIONS

Leptin promotes invasion of BeWo cells, and progesterone suppresses leptin-induced invasion by regulating the expressions of MMP-9, TIMP1, TIMP2, and E-cadherin. The balance between leptin and progesterone may play an important role in human placenta formation during early pregnancy.

The Elsevier Trophoblast Research Award Lecture: Importance of metzincin proteases in trophoblast biology and placental development: a focus on ADAM12

Placental development is a highly regulated process requiring signals from both fetal and maternal uterine compartments. Within this complex system, trophoblasts, placental cells of epithelial lineage, form the maternal-fetal interface controlling nutrient, gas and waste exchange. The commitment of progenitor villous cytotrophoblasts to differentiate into diverse trophoblast subsets is a fundamental process in placental development. Differentiation of trophoblasts into invasive stromal- and vascular-remodeling subtypes is essential for uterine arterial remodeling and placental function. Inadequate placentation, characterized by defects in trophoblast differentiation, may underlie the earliest cellular events driving pregnancy disorders such as preeclampsia and fetal growth restriction. Molecularly, invasive trophoblasts acquire characteristics defined by profound alterations in cell-cell and cell-matrix adhesion, cytoskeletal reorganization and production of proteolytic factors. To date, most studies have investigated the importance of the matrix metalloproteinases (MMPs) and their ability to efficiently remodel components of the extracellular matrix (ECM). However, it is now becoming clear that besides MMPs, other related proteases regulate trophoblast invasion via mechanisms other than ECM turnover. In this review, we will summarize the current knowledge on the regulation of trophoblast invasion by members of the metzincin family of metalloproteinases. Specifically, we will discuss the emerging roles that A Disintegrin and Metalloproteinases (ADAMs) play in placental development, with a particular focus on the ADAM subtype, ADAM12.

Deleterious effects of benomyl and carbendazim on human placental trophoblast cells

Benomyl and carbendazim are benzimidazole fungicides that are used throughout the world against a wide range of fungal diseases of agricultural products. There is as yet little information regarding the toxicity of benzimidazole fungicides to human placenta. In this study, we utilized human placental trophoblast cell line HTR-8/SVneo (HTR-8) to access the toxic effects of benomyl and carbendazim. Our data showed that these two fungicides decreased cell viability and the percentages of cells in G0/G1 phase, as well as induced apoptosis of HTR-8 cells. The invasion and migration of HTR-8 cells were significantly inhibited by benomyl and carbendazim. We further found that benomyl and carbendazim altered the expression of protease systems (MMPs/TIPMs and uPA/PAI-1) and adhesion molecules (integrin α5 and β1) in HTR-8 cells. Our present study firstly shows the deleterious effects of benomyl and carbendazim on placental cells and suggests a potential risk of benzimidazole fungicides to human reproduction.

The binucleate cell of okapi and giraffe placenta shows distinctive glycosylation compared with other ruminants: a lectin histochemical study

The placenta of ruminants contains characteristic binucleate cells (BNC) with a highly conserved glycan structure which evolved early in Ruminant phylogenesis. Giraffe and Okapi placentae also contain these cells and it is not known whether they have a similar glycan array. We have used lectin histochemistry to examine the glycosylation of these cells in these species and compare them with bovine BNC which have a typical ruminant glycan composition. Two placentae, mid and near term, from Giraffe (Giraffa camelopardalis) and two term placenta of Okapi (Okapia johnstoni) were embedded in resin and stained with a panel of 23 lectins and compared with near-term bovine (Bos taurus) placenta. Significant differences were found in the glycans of Giraffe and Okapi BNC compared with those from the bovine, with little or no expression of terminal αN-acetylgalactosamine bound by Dolichos biflorus and Vicia villosa agglutinins which instead bound to placental blood vessels. Higher levels of N-acetylglucosamine bound by Lycopersicon esculentum and Phytolacca americana agglutinins were also apparent. Some differences between Okapi and Giraffe were evident. Most N-linked glycans were similarly expressed in all three species as were fucosyl residues. Interplacentomal areas in Giraffe and Bovine showed differences from the placentomal cells though no intercotyledonary BNC were apparent in Okapi. In conclusion, Giraffidae BNC developed different glycan biosynthetic pathways following their split from the Bovidae with further differences evolving as Okapi and Giraffe diverged from each other, affecting both inter and placentomal BNC which may have different functions during development.

Pharmacological inhibition of MIF interferes with trophoblast cell migration and invasiveness

INTRODUCTION

Macrophage migration inhibitory factor (MIF) is expressed by villous and extravillous cytotrophoblast. This study was aimed to investigate functional relevance of MIF for human trophoblast.

METHODS

MIF mRNA and protein were documented in cytotrophoblast (CT) and extravillous trophoblast cell line HTR-8/SVneo by RT-PCR, Western blot (WB), and immunocytochemistry. Recombinant human MIF (rhMIF), or its specific inhibitor (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) were used in Wound healing migration and Matrigel invasion tests. Potential effectors, integrin subunits and matrix metalloproteinases (MMP) were studied using WB and gelatin zymography, respectively.

RESULTS

Blocking endogenous MIF by ISO-1 decreased HTR-8/SVneo cell migration dose dependently, most significantly with 200 μg/ml to 65% of control. Supplementation with rhMIF induced a significant stimulation to 129% of control with 200 ng/ml. In CT cell invasion test, ISO-1 at 200 μg/ml reduced invasion to 59% of control, while rhMIF (200 ng/ml) induced stimulation to 159% of control. In HTR-8/SVneo cells, invasion was significantly inhibited by ISO-1 to 40%, and increased to 150% of control by rhMIF (200 ng/ml). Integrin α1 was reduced by ISO-1 in both cell types, while integrins α5 and β1 were not changed. Addition of rhMIF increased integrin α1. In the presence of ISO-1, levels of MMP-2 and MMP-9 were reduced in CT and HTR-8/SVneo, while rhMIF stimulated MMP-2 in CT and MMP-9 in HTR-8/SVneo cells.

CONCLUSION

Reported findings provide the first insight into the cellular effects of MIF in human trophoblast, which acts to promote cell migration and invasion.

Three-dimensional cultures of trophoblast stem cells autonomously develop vascular-like spaces lined by trophoblast giant cells

The maternal blood space in the mouse placenta is lined not by endothelial cells but rather by various subtypes of trophoblast giant cells (TGCs), defined by their location and different patterns of gene expression. While TGCs invade the spiral arteries to displace the maternal endothelium, the rest of the vascular space is created de novo but the mechanisms are not well understood. We cultured mouse trophoblast stem (TS) cells in suspension and found that they readily form spheroids (trophospheres). Compared to cells grown in monolayer, differentiating trophospheres showed accelerated expression of TGC-specific genes. Morphological and gene expression studies showed that cavities form within the trophospheres that are primarily lined by Prl3d1/Pl1α-positive cells analogous to parietal-TGCs (P-TGCs) which line the maternal venous blood within the placenta. Lumen formation in trophospheres and in vivo was associated with cell polarization including CD34 sialomucin deposition on the apical side and cytoskeletal rearrangement. While P-TGCs preferentially formed in trophospheres at atmospheric oxygen levels (19%), decreasing oxygen to 3% shifted differentiation towards Ctsq-positive sinusoidal and/or channel TGCs. These studies show that trophoblast cells have the intrinsic ability to form vascular channels in ways analogous to endothelial cells. The trophosphere system will be valuable for assessing mechanisms that regulate specification of different TGC subtypes and their morphogenesis into vascular spaces.

Galectin-13/PP-13 expression in term placentas of gestational diabetes mellitus pregnancies

INTRODUCTION

Gestational diabetes mellitus (GDM) is an increasing harm in pregnancy. Inflammatory processes in the placenta seem to have an influence on pathogenesis besides known factors like maternal BMI. Galectin-13 (gal-13) is an immunoregulatory protein, which is suspected to play a role in development of GDM in the placenta.

METHODS

A total of 40 placentas were obtained from women treated for gestational diabetes mellitus. Placental tissue for control group was obtained from 40 women with normal pregnancy. We investigated the protein expression of gal-13 in term placentas with immunohistochemistry and immunofluorescence. Immunohistochemical staining was analyzed with the semi-quantified IRS score. Gal-13 serum levels were performed with ELISA on a total of 20 probes from women with GDM and healthy control pregnancies in the third trimester.

RESULTS

Gal-13 was found in syncytiotrophoblast, in nuclei of syncytiotrophoblast and trophoblast cells as well in extravillous trophoblast cells of normal placentas. In GDM placentas, gal-13 expression was significantly decreased in all of these examined cell types (syncytiotrophoblast p = 0.003, nuclei of syncytiotrophoblast p = 0.007; extravillous trophoblast cells p = 0.001). The ELISA showed a significant lower gal-13 serum level in blood from pregnant women with GDM in comparison to healthy controls.

DISCUSSION

As gal-13 with its anti-inflammatory functions plays a role in regulation of maternal immune system, a lack of gal-13 may contribute to an imbalance in inflammation processes in the placenta during pregnancy and therefore influences development of GDM.

Genome variation in the trophoblast cell lifespan: Diploidy, polyteny, depolytenization, genome segregation

The lifespan of mammalian trophoblast cells includes polyploidization, its degree and peculiarities are, probably, accounted for the characteristics of placenta development. The main ways of genome multiplication-endoreduplication and reduced mitosis-that basically differ by the extent of repression of mitotic events, play, most probably, different roles in the functionally different trophoblast cells in a variety of mammalian species. In the rodent placenta, highly polyploid (512-2048c) trophoblast giant cells (TGC) undergoing endoreduplication serve a barrier with semiallogenic maternal tissues whereas series of reduced mitoses allow to accumulate a great number of low-ploid junctional zone and labyrinth trophoblast cells. Endoreduplication of TGC comes to the end with formation of numerous low-ploid subcellular compartments that show some signs of viable cells though mitotically inactive; it makes impossible their ectopic proliferation inside maternal tissues. In distinct from rodent trophoblast, deviation from (2ⁿ)c in human and silver fox trophoblast suggests a possibility of aneuploidy and other chromosome changes (aberrations, etc.). It suggests that in mammalian species with lengthy period of pregnancy, polyploidy is accompanied by more diverse genome changes that may be useful to select a more specific response to stressful factors that may appear occasionally during months of intrauterine development.

The involvement of the trans-generational effect in the high incidence of the hydatidiform mole in Africa

INTRODUCTION

While the incidence of various chromosomal anomalies observed, including triploid partial moles is independent of the socio-economic level, higher incidences of complete hydatidiform mole "CHM" is generally associated with under developed areas. Moreover, studies have shown that some nutritional deficiencies are related to the abnormal development of oocytes and placenta. In Senegal and Morocco, the annual seasonal cycle contains one period with food shortages and the incidence of complete moles is significant. Accordingly, accurate statistical analyses have been performed in these two countries.

METHODS

Each month during a one year period, we investigated the occurrence of normal conceptions, molar conceptions and the conception of the future patients in Senegal and Morocco. The comparisons of the conception dates for these three types of conception were analyzed using the Chi-squared test.

RESULTS

94% of the patients were conceived just prior to the period in the year with food shortages. Consequently, the development of the female embryos occurred under nutritional constraints, which negatively affect the recruitment of the vital factors required for the normal synthesis of DNA, proteins and placental differentiation.

DISCUSSIONS

A nutritional deficiency in the mother at conception of their daughter (future patient) is implicated in the higher incidence of CHM in their daughters' filiation. These nutritional deficiencies during the first weeks of pregnancy will have repercussions on the normal development of the oocytes. Accordingly, these developmental impairments take place during the embryonic life of the future mothers of complete moles and not during the conception of the moles themselves.

Collagen type IV at the fetal-maternal interface

Introduction

Extracellular matrix proteins play a crucial role in influencing the invasion of trophoblast cells. However the role of collagens and collagen type IV (col-IV) in particular at the implantation site is not clear.

Methods

Immunohistochemistry was used to determine the distribution of collagen types I, III, IV and VI in endometrium and decidua during the menstrual cycle and the first trimester of pregnancy. Expression of col-IV alpha chains during the reproductive cycle was determined by qPCR and protein localisation by immunohistochemistry. The structure of col-IV in placenta was examined using transmission electron microscopy. Finally, the expression of col-IV alpha chain NC1 domains and collagen receptors was localised by immunohistochemistry.

Results

Col-IV alpha chains were selectively up-regulated during the menstrual cycle and decidualisation. Primary extravillous trophoblast cells express collagen receptors and secrete col-IV in vitro and in vivo, resulting in the increased levels found in decidua basalis compared to decidua parietalis. A novel expression pattern of col-IV in the mesenchyme of placental villi, as a three-dimensional network, was found. NC1 domains of col-IV alpha chains are known to regulate tumour cell migration and the selective expression of these domains in decidua basalis compared to decidua parietalis was determined.

Discussion

Col-IV is expressed as novel forms in the placenta. These findings suggest that col-IV not only represents a structural protein providing tissue integrity but also influences the invasive behaviour of trophoblast cells at the implantation site.

•

Our data suggest that progesterone might regulate collagen type IV.

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Primary extravillous trophoblast cells secrete collagen type IV.

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A novel three-dimensional network of collagen type IV in placenta is presented.

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Trophoblast cells express integrin alpha 10, integrin alpha 11 and collagen receptors DDR-1 and DDR-2.

Elf5 and Ets2 maintain the mouse extraembryonic ectoderm in a dosage dependent synergistic manner

The ETS superfamily transcription factors Elf5 and Ets2 have both been implicated in the maintenance of the extraembryonic ectoderm (ExE) of the mouse embryo. While homozygous mutants of either gene result in various degrees of ExE tissue loss, heterozygotes are without phenotype. We show here that compound heterozygous mutants exhibit a phenotype intermediate to that of the more severe Elf5-/- and the milder Ets2-/- mutants. Functional redundancy is shown via commonalities in expression patterns, in target gene expression, and by partial rescue of Elf5-/- mutants through overexpressing Ets2 in an Elf5-like fashion. A model is presented suggesting the functional division of the ExE region into a proximal and distal domain based on gene expression patterns and the proximal to distal increasing sensitivity to threshold levels of combined Elf5 and Ets2 activity.

Increased trophoblast expression of NFAT5/TonEBP in pre-eclamptic placentas and hyperosmolar-treated BeWo cells

OBJECTIVES

To assess the concentrations of inositol and sorbitol, and determine the expression of related osmolyte factors [nuclear factor of activated T cells 5, also known as tonicity responsive binding protein (NFAT5/TonEBP); sodium myo-inositol transporter (SLC5A3); and aldose reductase] in placentas of pre-eclamptic (PE) patients and trophoblast BeWo cells subjected to hypertonic stress in vitro.

STUDY DESIGN

Control and PE placentas were collected. BeWo cells were cultured and subjected to a hyperosmolar solution for 4h. Western blot analysis was performed on NFAT5, SLC5A3, aldose reductase and ERK proteins. High-performance liquid chromatography was used to determine the levels of inositol and sorbitol in cell lysates.

RESULTS

Compared with control placentas, PE placentas showed higher levels of inositol and NFAT5, and lower levels of SLC5A3. Treated BeWo cells showed higher levels of inositol, sorbitol, NFAT5 total protein, SLC5A3 and aldose reductase, and increased ERK activation compared with control BeWo cells.

CONCLUSIONS

Hyperosmolar conditions increase the expression of NFAT5 in PE placentas and BeWo cells, and may account for the increased osmolyte levels. NFAT5 may accomplish this through aldose reductase and SLC5A3 in trophoblast cells.

miR-125b-1-3p inhibits trophoblast cell invasion by targeting sphingosine-1-phosphate receptor 1 in preeclampsia

Preeclampsia (PE) is the leading cause of maternal and perinatal mortality and morbidity. Understanding the molecular mechanisms underlying placentation facilitates the development of better intervention of this disease. MicroRNAs are strongly implicated in the pathogenesis of this syndrome. In current study, we found that miR-125b-1-3p was elevated in placentas derived from preeclampsia patients. Transfection of miR-125b-1-3p mimics significantly inhibited the invasiveness of human trophoblast cells, whereas miR-125b-1-3p inhibitor enhanced trophoblast cell invasion. Luciferase assays identified that S1PR1 was a novel direct target of miR-125b-1-3p in the placenta. Overexpression of S1PR1 could reverse the inhibitory effect of miR-125b-1-3p on the invasion of trophoblast cells. These findings suggested that abnormal expression of miR-125b-1-3p might contribute to the pathogenesis of preeclampsia.

Spontaneous reactivation of clusters of X-linked genes is associated with the plasticity of X-inactivation in mouse trophoblast stem cells

Random epigenetic silencing of the X-chromosome in somatic tissues of female mammals equalizes the dosage of X-linked genes between the sexes. Unlike this form of X-inactivation that is essentially irreversible, the imprinted inactivation of the paternal X, which characterizes mouse extra-embryonic tissues, appears highly unstable in the trophoblast giant cells of the placenta. Here, we wished to determine whether such instability is already present in placental progenitor cells prior to differentiation toward lineage-specific cell types. To this end, we analyzed the behavior of a GFP transgene on the paternal X both in vivo and in trophoblast stem (TS) cells derived from the trophectoderm of XX(GFP) blastocysts. Using single-cell studies, we show that not only the GFP transgene but also a large number of endogenous genes on the paternal X are subject to orchestrated cycles of reactivation/de novo inactivation in placental progenitor cells. This reversal of silencing is associated with local losses of histone H3 lysine 27 trimethylation extending over several adjacent genes and with the topological relocation of the hypomethylated loci outside of the nuclear compartment of the inactive X. The "reactivated" state is maintained through several cell divisions. Our study suggests that this type of "metastable epigenetic" states may underlie the plasticity of TS cells and predispose specific genes to relaxed regulation in specific subtypes of placental cells.

The influence of ligand-activated LXR on primary human trophoblasts

INTRODUCTION

The Liver X Receptors (LXRs) are critical transcriptional regulators of cellular metabolism that promote cholesterol efflux and lipogenesis in response to excess intracellular cholesterol. In contrast, the Sterol Response Element Binding Protein-2 (SREBP2) promotes the synthesis and uptake of cholesterol. Oxysterols are products of cholesterol oxidation that accumulate in conditions associated with increased cellular levels of reactive oxygen species, such as hypoxia and oxidative stress, activating LXR and inhibiting SREBP2. While hypoxia and oxidative stress are commonly implicated in placental injury, the impact of the transcriptional regulation of cholesterol homeostasis on placental function is not well characterized.

METHODS

We measured the effects of the synthetic LXR ligand T0901317 and the endogenous oxysterol 25-hydroxycholesterol (25OHC) on differentiation, cytotoxicity, progesterone synthesis, lipid droplet formation, and gene expression in primary human trophoblasts.

RESULTS

Exposure to T0901317 promoted lipid droplet formation and inhibited differentiation, while 25OHC induced trophoblast toxicity, promoted hCG and progesterone release at lower concentrations with inhibition at higher concentrations, and had no effect on lipid droplet formation. The discrepant effect of these ligands was associated with distinct changes in expression of LXR and SREBP2 target genes, with upregulation of ABCA1 following 25OHC and T090317 exposure, exclusive activation of the lipogenic LXR targets SREBP1c, ACC1 and FAS by T0901317, and exclusive inhibition of the SREBP2 targets LDLR and HMGCR by 25OHC.

CONCLUSION

These findings implicate cholesterol oxidation as a determinant of trophoblast function and activity, and suggest that placental gene targets and functional pathways are selectively regulated by specific LXR ligands.

Functional antagonism between high temperature requirement protein A (HtrA) family members regulates trophoblast invasion

Human trophoblast invasion of decidualized endometrium is essential for placentation and is tightly regulated and involves trophoblast-decidual cell interaction. High temperature requirement A4 (HtrA4) is a secreted serine protease highly expressed in the invasive extravillous trophoblasts that invade decidua. In contrast, both HtrA1 and HtrA3 have been shown to inhibit trophoblast invasion. Here we provide evidence that decidua-secreted HtrA1 and HtrA3 antagonize HtrA4-mediated trophoblast invasion. We demonstrated that HtrA1 and HtrA3 interact with and degrade HtrA4 and thereby inhibit trophoblast-like JAR cell invasion. Specifically, HtrA1 and HtrA3 expression is up-regulated under decidualization conditions in endometrial stromal and epithelial cells, T-HESCs and Ishikawa cells, respectively. Conditioned media from these two cell lines after decidualization treatment suppress HtrA4-expressing JAR cell invasion in an HtrA1- or HtrA3-dependent manner. Co-culture of the HtrA4-expressing JAR cells with decidualization stimuli-treated T-HESC or Ishikawa monolayer also impairs JAR cell invasion, which can be reversed by HtrA1 or HtrA3 knockdown, supporting that HtrA1 and HtrA3 are crucial for trophoblast-decidual cell interaction in the control of trophoblast invasion. Our study reveals a novel regulatory mechanism of trophoblast invasion through physical and functional interaction between HtrA family members.

The cAMP-responsive element binding protein (CREB) transcription factor regulates furin expression during human trophoblast syncytialization

INTRODUCTION

The multinucleated syncytiotrophoblast is formed and maintained by cytotrophoblast cell fusion and serves multiple functions to ensure a successful pregnancy. We have previously reported that the proprotein convertase furin is required for trophoblast syncytialization by processing type 1 insulin-like growth factor receptor (IGF1R).

METHODS

Utilizing trophoblast cell fusion models including induced fusion of choriocarcinoma BeWo cells and spontaneous fusion of primary cultured term cytotrophoblast cells, the expression of furin was evaluated by quantitative real-time PCR, Western blotting and immunofluorescence. The key transcription factor regulating the FUR gene promoter and critical responsive elements were identified by luciferase reporter assays, truncated mutants analysis, site-directed mutagenesis and ChIP.

RESULTS

We demonstrated that the levels of FUR mRNA were significantly stimulated by cAMP/PKA signaling pathway during spontaneous fusion of cytotrophoblast cells and forskolin-induced fusion of BeWo cells. cAMP-responsive element binding protein (CREB) was proven to be the key transcription factor which regulated the FUR P1 promoter during forskolin-induced BeWo cell fusion, and two critical cAMP-responsive elements (CREs) in the P1 promoter were further identified. Finally, we showed that CREB mediated endogenous furin activation and that CREB siRNA attenuated forskolin-induced furin expression and cell fusion in BeWo cells.

DISCUSSION

This provides the first evidence of the upstream regulator of furin during trophoblast cell fusion.

CONCLUSIONS

The above results suggest that the FUR transcription is activated by CREB-dependent stimulation of the FUR P1 promoter during human trophoblast syncytialization.

MicroRNA regulation of mitogenic signaling networks in the human placenta

Placental cell growth depends on an adaptable combination of an endogenous developmental program and the exogenous influence of maternal growth factors, both of which may be influenced by microRNA (miR)-dependent effects on gene expression. We have previously shown that global miR suppression in placenta accelerates proliferation and enhances levels of growth factor signaling mediators in cytotrophoblast. This study aimed to identify miRs involved in regulating placental growth. An initial array revealed 58 miR species whose expression differs between first trimester, when cytotrophoblast proliferation is rapid, and term, by which time proliferation has slowed. In silico analysis defined potential growth-regulatory miRs; among these, hsa-miR-145, hsa-miR-377, and hsa-let-7a were predicted to target known placental growth genes and were higher at term than in the first trimester, so they were selected for further analysis. Overexpression of miR-377 and let-7a, but not miR-145, in first trimester placental explants significantly reduced basal cytotrophoblast proliferation and expression of ERK and MYC. PCR arrays, in silico analysis, Western blotting, and 3'-UTR luciferase reporter assays revealed targets of miR-145 within the insulin-like growth factor axis. Analysis of proliferation in placental explants overexpressing miR-145 demonstrated its role as a mediator of insulin-like growth factor-induced trophoblast proliferation. These findings identify miR-377 and let-7a in regulation of endogenous cell growth and miR-145 in the placental response to maternal stimulation and will aid the development of therapeutic strategies for problem pregnancies.

Fatty acid binding protein-4 is expressed in the mouse placental labyrinth, yet is dispensable for placental triglyceride accumulation and fetal growth

INTRODUCTION

Fatty Acid Binding Protein-4 (FABP4) is a member of a family of FABP proteins that regulate intracellular lipid trafficking in diverse tissues. We recently showed that FABP4 regulates triglyceride accumulation in primary human trophoblasts. To assess the function of placental FABP4 in vivo, we tested the hypothesis that FABP4 is expressed in the murine placenta, and regulates placenta triglyceride accumulation.

METHODS

C57Bl/6 wild type or Fabp4-null mice were time-bred, and fetuses and placentas harvested at different time points during pregnancy. Placental FABP4 expression was assessed at different gestational ages, using quantitative PCR, immunohistochemistry, immunofluorescence and western immunoblotting. FABPs expression was examined by RT-qPCR. Placental lipids were extracted using the Folch method and triglyceride levels determined using a colorimetric quantification kit.

RESULTS

Using immunohistochemistry, we found that FABP4 was expressed in the placental labyrinthine layer, predominantly in endothelial cells in association with CD31 positive fetal capillaries. The level of placental FABP4 mRNA and protein increased from E12.5 to E16.5 and slightly decreased at E18.5. Breeding of Fabp4 heterozygous mice resulted in embryonic genotypes that followed a Mendelian distribution and exhibited normal weight and morphology, triglyceride content, and expression of other FABP family members. Exposure to hypoxia (O2 = 12%) between E12.5-E18.5 did not uncover a difference between wild type and Fabp4-null mice.

CONCLUSIONS

FABP4 is expressed in the mouse placental labyrinth, with highest expression at E16.5. FABP4 is dispensable for feto-placental growth and placental lipid accumulation.

Important aspects of placental-specific gene transfer

The placenta is a unique and highly complex organ that develops only during pregnancy and is essential for growth and survival of the developing fetus. The placenta provides the vital exchange of gases and wastes, the necessary nutrients for fetal development, acts as immune barrier that protects against maternal rejection, and produces numerous hormones and growth factors that promote fetal maturity to regulate pregnancy until parturition. Abnormal placental development is a major underlying cause of pregnancy-associated disorders that often result in preterm birth. Defects in placental stem cell propagation, growth, and differentiation are the major factors that affect embryonic and fetal well-being and dramatically increase the risk of pregnancy complications. Understanding the processes that regulate placentation is important in determining the underlying factors behind abnormal placental development. The ability to manipulate genes in a placenta-specific manner provides a unique tool to analyze development and eliminates potentially confounding results that can occur with traditional gene knockouts. Trophoblast stem cells and mouse embryos are not overly amenable to traditional gene transfer techniques. Most viral vectors, however, have a low infection rate and often lead to mosaic transgenesis. Although the traditional method of embryo transfer is intrauterine surgical implantation, the methodology reported here, combining lentiviral blastocyst infection and nonsurgical embryo transfer, leads to highly efficient and placental-specific gene transfer. Numerous advantages of our optimized procedures include increased investigator safety, a reduction in animal stress, rapid and noninvasive embryo transfer, and higher a rate of pregnancy and live birth.

Apoptosis of alcohol-exposed human placental cytotrophoblast cells is downstream of intracellular calcium signaling

BACKGROUND

Apoptosis is induced by ethanol (EtOH) in human placental trophoblast cells, possibly disrupting placentation and contributing to intrauterine growth restriction in fetal alcohol spectrum disorder (FASD). EtOH induces programmed cell death in several embryonic tissues by raising intracellular Ca(2+) . Therefore, the role of Ca(2+) signaling in EtOH-induced apoptosis was examined using human first trimester cytotrophoblast cell lines, examining the hypothesis that apoptosis is dependent on intracellular Ca(2+) signaling.

METHODS

Using HTR-8/SVneo and SW.71 cytotrophoblast cell lines, real-time intracellular Ca(2+) concentration was monitored by fluo-4 epifluorescence microscopy and apoptosis was assessed by flow cytometry of cells fluorescently labeled for DNA fragmentation (TUNEL) and annexin V binding.

RESULTS

Intracellular Ca(2+) concentrations increased synchronously in all cells within 10 seconds of exposure to 50 mM EtOH, but not at lower EtOH concentrations (10 to 25 mM) incapable of inducing apoptosis. Trophoblast cells treated with inhibitors of Ca(2+) signaling (BAPTA-AM, U73122, xestospongin D, BAPTA, SKF-96365) produced no intracellular Ca(2+) transients after exposure to 50 mM EtOH and were protected from cell death induced by EtOH.

CONCLUSIONS

EtOH-induced apoptosis in human cytotrophoblast cells, identified by DNA fragmentation and externalized phosphatidylserine, was dependent upon Ca(2+) signaling. Both intracellular Ca(2+) mobilization and extracellular Ca(2+) influx were required, as well as phosphatidylinositol signaling. Inhibition by SKF-96365 suggests that the capacitative Ca(2+) entry mechanism that utilizes TRPC channels was activated by EtOH. Apoptosis occurs downstream of Ca(2+) signaling in trophoblasts and may contribute to placental insufficiency and poor fetal growth associated with FASD.

Nodal signals via β-arrestins and RalGTPases to regulate trophoblast invasion

Placentation is critical for establishing a healthy pregnancy. Trophoblasts mediate implantation and placentation and certain subtypes, most notably extravillous cytotrophoblast, are highly invasive. Trophoblast invasion is tightly regulated by microenvironmental cues that dictate placental morphology and depth. In choriocarcinomas, malignant trophoblast cells become hyperinvasive, breaching the myometrium and leading to major complications. Nodal, a member of the TGF-β superfamily, is expressed throughout the endometrium during the peri-implantation period and in invasive trophoblast cells. Nodal promotes the invasion of numerous types of cancer cells. However, Nodal's role in trophoblast and choriocarcinoma cell invasion is unclear. Here we show that Nodal stimulates the invasion of both the non-malignant HTR-8SV/neo trophoblast and JAR choriocarcinoma cells in a dose-dependent manner. We found that endogenous β-arrestins and Ral GTPases, key regulators of the cell cytoskeleton, are constitutively associated with Nodal receptors (ALK4 and ALK7) in trophoblast cells and that RalA is colocalized with ALK4 in endocytic vesicles. Nodal stimulates endogenous β-arrestin2 to associate with phospho-ERK1/2, and knockdown of β-arrestin or Ral proteins impairs Nodal-induced trophoblast and choriocarcinoma cell invasion. These results demonstrate, for the first time, that β-arrestins and RalGTPases are important regulators of Nodal-induced invasion.

Elf5 counteracts precocious trophoblast differentiation by maintaining Sox2 and 3 and inhibiting Hand1 expression

In mice the transcription factor Elf5 is necessary for correct trophoblast development. Upon knockdown of Elf5, TS cells display neither a decrease in proliferation nor an increase in cell death but rather an increased propensity to differentiate. Such cells rapidly lose Sox2 and 3 expression, while transiently upregulating the giant cell differentiation determinant gene Hand1. Other genes affected within 24h of Elf5 knock-down, many of which have not previously been implicated in trophoblast development, exhibited in vivo expression domains and in vitro expression responses consistent with Elf5 having a role in counteracting trophoblast differentiation. In an ES to TS differentiation assay using Cdx2 overexpression with Elf5 loss of function cell lines, it was shown that Elf5 is necessary to prevent terminal trophoblast differentiation. This data thus suggest that Elf5 is a gatekeeper for the TS to differentiated trophoblast transition thereby preventing the precocious differentiation of the undifferentiated extraembryonic ectoderm.

Hectd1 is required for development of the junctional zone of the placenta

The placenta plays a critical role in the growth and survival of the fetus. Here we demonstrate that the Homologous to the E6-AP Carboxyl Terminus (HECT) domain E3 ubiquitin ligase, Hectd1, is essential for development of the mouse placenta. Hectd1 is widely expressed during placentation with enrichment in trophoblast giant cells (TGCs) and other trophoblast-derived cell subtypes in the junctional and labyrinth zones of the placenta. Disruption of Hectd1 results in mid-gestation lethality and intrauterine growth restriction (IUGR). Variable defects in the gross structure of the mutant placenta are found including alterations in diameter, thickness and lamination. The number and nuclear size of TGCs is reduced. Examination of subtype specific markers reveals altered TGC development with decreased expression of Placental lactogen-1 and -2 (Pl1 and Pl2) and increased expression of Proliferin (Plf). Reduced numbers of spongiotrophoblasts and glycogen trophoblasts were also found at the junctional zone of the Hectd1 mutant placenta. Finally, there was an increase in immature uterine natural killer (uNK) cells in the maternal decidua of the Hectd1 mutant placenta. Proliferation and apoptosis are differentially altered in the layers of the placenta with an increase in both apoptosis and proliferation in the maternal decidua, a decrease in proliferation and increase in apoptosis in the labyrinth layer and both unchanged in the junctional zone. Together these data demonstrate that Hectd1 is required for development of multiple cell types within the junctional zone of the placenta.

Placental alkaline phosphatase de-phosphorylates insulin-like growth factor (IGF)-binding protein-1

BACKGROUND

Insulin-like growth factors (IGF) regulate fetal growth through their effects on placenta. Their actions are influenced by IGF binding protein-1. Phosphorylated IGFBP-1 (pIGFBP-1) has high affinity for IGF-I and usually inhibits IGF-I activity but during pregnancy, it is de-phosphorylated to generate lower affinity isoforms and consequently, increased IGF bioavailability. Here we investigate the role of placenta in this process.

RESULTS

Our data show that term human placental explants, but not their conditioned medium, can de-phosphorylate IGFBP-1 through the action of placental alkaline phosphatase (PLAP).

DISCUSSION

PLAP-mediated de-phosphorylation of IGFBP-1 may provide a mechanism for controlling IGF-I bioavailability and action at the maternal/fetal interface.

Exocyst complex protein expression in the human placenta

INTRODUCTION

Protein production and secretion are essential to syncytiotrophoblast function and are associated with cytotrophoblast cell fusion and differentiation. Syncytiotrophoblast hormone secretion is a crucial determinant of maternal-fetal health, and can be misregulated in pathological pregnancies. Although, polarized secretion is a key component of placental function, the mechanisms underlying this process are poorly understood.

OBJECTIVE

While the octameric exocyst complex is classically regarded as a master regulator of secretion in various mammalian systems, its expression in the placenta remained unexplored. We hypothesized that the syncytiotrophoblast would express all exocyst complex components and effector proteins requisite for vesicle-mediated secretion more abundantly than cytotrophoblasts in tissue specimens.

METHODS

A two-tiered immunobiological approach was utilized to characterize exocyst and ancillary proteins in normal, term human placentas. Exocyst protein expression and localization was documented in tissue homogenates via immunoblotting and immunofluorescence labeling of placental sections.

RESULTS

The eight exocyst proteins, EXOC1, 2, 3, 4, 5, 6, 7, and 8, were found in the human placenta. In addition, RAB11, an important exocyst complex modulator, was also expressed. Exocyst and Rab protein expression appeared to be regulated during trophoblast differentiation, as the syncytiotrophoblast expressed these proteins with little, if any, expression in cytotrophoblast cells. Additionally, exocyst proteins were localized at or near the syncytiotrophoblast apical membrane, the major site of placental secretion.

DISCUSSION/CONCLUSION

Our findings highlight exocyst protein expression as novel indicators of trophoblast differentiation. The exocyst's regulated localization within the syncytiotrophoblast in conjunction with its well known functions suggests a possible role in placental polarized secretion.

Novel expression of EGFL7 in placental trophoblast and endothelial cells and its implication in preeclampsia

The mammalian placenta is the site of nutrient and gas exchange between the mother and fetus, and is comprised of two principal cell types, trophoblasts and endothelial cells. Proper placental development requires invasion and differentiation of trophoblast cells, together with coordinated fetal vasculogenesis and maternal vascular remodeling. Disruption in these processes can result in placental pathologies such as preeclampsia (PE), a disease characterized by late gestational hypertension and proteinuria. Epidermal Growth Factor Like Domain 7 (EGFL7) is a largely endothelial-restricted secreted factor that is critical for embryonic vascular development, and functions by modulating the Notch signaling pathway. However, the role of EGFL7 in placental development remains unknown. In this study, we use mouse models and human placentas to begin to understand the role of EGFL7 during normal and pathological placentation. We show that Egfl7 is expressed by the endothelium of both the maternal and fetal vasculature throughout placental development. Importantly, we uncovered a previously unknown site of EGFL7 expression in the trophoblast cell lineage, including the trophectoderm, trophoblast stem cells, and placental trophoblasts. Our results demonstrate significantly reduced Egfl7 expression in human PE placentas, concurrent with a downregulation of Notch target genes. Moreover, using the BPH/5 mouse model of PE, we show that the downregulation of Egfl7 in compromised placentas occurs prior to the onset of characteristic maternal signs of PE. Together, our results implicate Egfl7 as a possible factor in normal placental development and in the etiology of PE.

The relationship between TGFβ, low oxygen and the outgrowth of extravillous trophoblasts from anchoring villi during the first trimester of pregnancy

BACKGROUND

During the first trimester of human pregnancy, specialised placental cells called extravillous trophoblasts (EVTs) grow out from anchoring villi, invade the maternal decidua and remodel the uterine spiral arteries. Inadequate EVT invasion is associated with pregnancy complications including intrauterine growth restriction (IUGR) and pre-eclampsia. During early pregnancy, the placenta exists in a physiologically normal low oxygen environment, which may regulate EVT outgrowth. One potential oxygen responsive regulator of EVTs is the transforming growth factor-beta (TGFβ) family of cytokines. This work aimed to determine the role of TGFβ1, β2 and β3 in regulating EVT outgrowth in the low oxygen environment of early pregnancy.

RESULTS

Using a quantitative high-throughput first trimester villous explant model of EVT outgrowth we demonstrated no significant difference in the frequency of EVT outgrowth between explants treated with TGFβ1, β2 or β3. However, explants treated with TGFβ2, but not β1 or β3, produced EVT outgrowths with a significantly smaller area in comparison to untreated controls (p=0.03). When explants were cultured in 1.5% oxygen, TGFβ2, but not β1 or β3, in the conditioned medium of explants that produced EVT outgrowth was significantly reduced in comparison to 8% oxygen (p<0.05). There was no significant difference in the concentration of TGFβ2 or TGFβ3 from isolated primary EVTs cultured in 1.5% or 8% oxygen.

CONCLUSIONS

TGFβ2 inhibits EVT outgrowth expansion from first trimester anchoring villi. As TGFβ2 secretion from anchoring villi is down-regulated in low oxygen, these findings suggest that the low oxygen environment in early pregnancy may be important to allow EVT outgrowth expansion and promote adequate placentation.

Validation of an interferon stimulatory response element reporter gene assay for quantifying type I interferons

The goal of this work was to develop a virus-free, cell-based interferon (IFN) bioassay and determine the utility of this assay on biological samples that contained IFN-τ, the trophoblast-secreted maternal recognition of pregnancy factor in ruminants. Madin-Darby bovine kidney cells were transduced with lentiviral particles that contained a firefly luciferase reporter construct driven by an IFN stimulatory response element (ISRE). Stably transduced cells were selected with the use of puromycin resistance. A linear, dose-responsive response was detected with human IFN-α and ovine IFN-τ. Interferon activity was detected in conditioned media from bovine trophoblast cells and uterine flushes collected from sheep and cattle. Activity also was detected in media collected after individual or small group culture of in vitro-produced bovine blastocysts at day 8 to 10 after fertilization. In summary, this IFN stimulatory response element-reporter assay may be used as an alternative to virus-dependent, cytopathic assays. It contains a similar sensitivity to IFNs and can be completed in a shorter time than cytopathic assays and does not require heightened biosafety conditions after cell transduction.

Interaction between human placental microvascular endothelial cells and a model of human trophoblasts: effects on growth cycle and angiogenic profile

Abstract Intrauterine growth restriction (IUGR) is a leading cause of perinatal complications, and is commonly associated with reduced placental vasculature. Recent studies demonstrated over-expression of IGF-1 in IUGR animal models maintains placental vasculature. However, the cellular environment of the placental chorionic villous is unknown. The close proximity of trophoblasts and microvascular endothelial cells in vivo alludes to autocrine/paracrine regulation following Ad-HuIGF-1 treatment. We investigated the co-culturing of BeWo Choriocarcinoma and Human Placental Microvascular Endothelial Cells (HPMVECs) on the endothelial angiogenic profile and the effect Ad-HuIGF-1 treatment of one cell has on the other. HPMVECs were isolated from human term placentas and cultured in EGM-2 at 37°C with 5% CO2. BeWo cells were maintained in Ham's F12 nutrient mix with 10% FBS and 1% pen/strep. Co-cultured HPMVECS+BeWo cells were incubated in serum-free control media, Ad-HuIGF-1, or Ad-LacZ at MOI 0 and MOI 100:1 for 48 h. Non-treated cells and mono-cultured cells were compared to co-cultured cells. Angiogenic gene expression and proliferative and apoptotic protein expression were analysed by RT-qPCR and immunocytochemistry, respectively. Statistical analyses was performed using student's t-test with P < 0.05 considered significant. Direct Ad-HuIGF-1 treatment increased HPMVEC proliferation (n = 4) and reduced apoptosis (n = 3). Co-culturing HPMVECs+BeWo cells significantly altered RNA expression of the angiogenic profile compared to mono-cultured HPMVECs (n = 8). Direct Ad-HuIGF-1 treatment significantly increased Ang-1 (n = 4) in BeWo cells. Ad-HuIGF-1 treatment of HPMVECs did not alter the RNA expression of angiogenic factors. Trophoblastic factors may play a key role in placental vascular development and IGF-1 may have an important role in HPMVEC growth.