Fetal-Derived Trophoblast Use the Apoptotic Cytokine Tumor Necrosis Factor-α–Related Apoptosis-Inducing Ligand to Induce Smooth Muscle Cell Death

Apoptotic Receptors and CD107a Expression by NK Cells in an Interaction Model with Trophoblast Cells

Natural killer cells (NK cells) exert cytotoxicity towards target cells in several ways, including the expression of apoptosis-mediating ligands (TRAIL, FasL). In addition, NK cells themselves may be susceptible to apoptosis due to the expression of TRAIL receptors. These receptors include TRAIL-R1 (DR4), TRAIL-R2 (DR5), capable of inducing apoptosis, and TRAIL-R3 (DcR1), TRAIL-R4 (DcR2), the so-called "decoy receptors", which lack an intracellular domain initiating activation of caspases. Of particular interest is the interaction of uterine NK cells with cells of fetal origin, trophoblasts, which are potential targets for natural killer cells to carry out cytotoxicity. The aim of this work was to evaluate the expression of proapoptotic receptors and their ligands as well as CD107a expression by NK cells in a model of interaction with trophoblast cells. To evaluate NK cells, we used cells of the NK-92 line; cells of the JEG-3 line were used as target cells. The cytokines IL-1β, IL-15, IL-18, TNFα, IL-10, TGFβ and conditioned media (CM) of the first and third trimester chorionic villi explants were used as inducers. We established that cytokines changed the expression of apoptotic receptors by NK cells: in the presence of TNFα, the amount and intensity of Fas expression increased, while in the presence of TGFβ, the amount and intensity of expression of the DR5 receptor decreased. Soluble chorionic villi factors alter the expression of TRAIL and FasL by NK-92 cells, which can reflect the suppression of the TRAIL-dependent mechanism of apoptosis in the first trimester and stimulating the Fas-dependent mechanism in the third trimester. In the presence of trophoblast cells, the expression of TRAIL and DcR1 by NK cells was reduced compared to intact cells, indicating an inhibitory effect of trophoblast cells on NK cell cytotoxicity. In the presence of chorionic villi CM and trophoblast cells, a reduced number of NK-92 cells expressing DR4 and DR5 was found. Therefore, soluble factors secreted by chorionic villi cells regulate the resistance of NK cells to death by binding TRAIL, likely maintaining their activity at a certain level in case of contact with trophoblast cells.

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

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

Cellular Prion protein moonlights vascular smooth muscle cell fate: Surveilled by trophoblast cells

Uterine spiral artery remodeling (uSAR) is a hallmark of hemochorial placentation. Compromised uSAR leads to adverse pregnancy outcomes. Salient developmental events involved in uSAR are active areas of research and include (a) trophendothelial cell invasion into the spiral arteries, selected demise of endothelial cells; (b) de-differentiation of vascular smooth muscle cells (VSMC); and (c) migration and/or death of VSMCs surrounding spiral arteries. Here we demonstrated that cellular prion (PRNP) is expressed in the rat metrial gland, the entry point of spiral arteries with the highest expression on E16.5, the day at which trophoblast invasion peaks. PRNP is expressed in VSMCs that drift away from the arterial wall. RNA interference of Prnp functionally restricted migration and invasion of rat VSMCs. Furthermore, PRNP interacted with two migration-promoting factors, focal adhesion kinase (FAK) and platelet-derived growth factor receptor-β (PDGFR-β), forming a ter-molecular complex in both the metrial gland and A7r5 cells. The presence of multiple putative binding site of odd skipped related-1 (OSR1) transcription factor on the Prnp promoter was observed using in silico promoter analysis. Ectopic overexpression of OSR1 increased, and knockdown of OSR1 decreased expression of PRNP in VSMCs. Coculture of VSMCs with rat primary trophoblast cells decreased the levels of OSR1 and PRNP. Interestingly, PRNP knockdown led to apoptotic death in ~9% of VSMCs and activated extrinsic apoptotic pathways. PRNP interacts with TRAIL-receptor DR4 and protects VSMCs from TRAIL-mediated apoptosis. These results highlight the biological functions of PRNP in VSMC cell-fate determination during uteroplacental development, an important determinant of healthy pregnancy outcome.

Circulating inflammatory cytokines and hypertensive disorders of pregnancy: a two-sample Mendelian randomization study

Background

Hypertensive disorders of pregnancy (HDP) pose a significant risk to maternal and fetal well-being; however, the etiology and pathogenesis of HDP remain ambiguous. It is now widely acknowledged that inflammatory response and the immune system are closely related to HDP. Previous research has identified several inflammatory cytokines are associated with HDP. This study applied Mendelian randomization (MR) analysis to further assess causality.

Methods

Patients with HDP who participated in the MR analysis presented with four types of HDP: pre-eclampsia or eclampsia (PE); gestational hypertension (GH); pre-existing hypertension complicating pregnancy, childbirth and the puerperium (EH); and pre-eclampsia or poor fetal growth (PF). A two-sample MR analysis was used to analyze the data in the study. The causal relationship between exposure and outcome was analyzed with inverse variance weighting (IVW), MR Egger, weighted median, weighted mode, and simple mode methods, where IVW was the primary method employed.

Results

Our MR analysis demonstrated a reliable causative effect of Interleukin-9 (IL-9) and macrophage migration inhibitory factor (MIF) on reducing HDP risk, while macrophage inflammatory protein 1-beta (MIP1b), Interleukin-13 (IL-13), and Interleukin-16 (IL-16) were associated with promoting HDP risk.

Conclusions

This study demonstrated that IL-9, MIF, MIP1b, IL-13, and IL-16 may be cytokines associated with the etiology of HDP, and that a number of inflammatory cytokines are probably involved in the progression of HDP. Additionally, our study revealed that these inflammatory cytokines have causal associations with HDP and may likely be potential therapeutic targets for HDP.

Bioavailability of the tumor necrosis factor alpha/regulated on activation, normal T cell expressed and secreted (RANTES) biosystem inside the gestational sac during the pre-immune stages of embryo development

OBJECTIVES

In-vivo studies of the bioavailability of major components of the tumor necrosis factor alpha (TNFα) biosystem inside the gestational sac during embryogenesis have not been reported. We sought to determine the concentration of TNFα, soluble (s) TNFα receptors (sTNFR1, sTNFR2), and RANTES in the primate extraembryonic celomic fluid (ECF).

METHODS

A validated timed-pregnant baboon animal model (N: 10) for experimental research in pregnancy was used to collect paired maternal blood and ECF samples in ongoing pregnancies. The concentrations (pg/dL) of TNFα, sTNFR1, sTNFR2, and RANTES were then determined by ELISA immunoassays.

RESULTS

All animals delivered at term healthy newborns. The differential concentration of TNFα, sTNFR1, sTNFR2, and RANTES between the maternal plasma and the ECF could be determined with ratios for TNFα (5.4), sTNFR2 (1.85) and RANTES (3.59) that contrasted with that of sTNFR1 (0.07), which favored the gestational sac compartment. No significant correlations were noted between maternal plasma and ECF TNFR1, sTNFR2 and RANTES. There was a trend for a correlation between TNFα in maternal plasma and ECF (R=0.74; p=0.07).

CONCLUSIONS

We report the physiological concentrations of TNFα, sTNFR1, sTNFR2, and RANTES in extraembryonic celomic fluid during embryogenesis in primates.

Unraveling the mysteries of spiral artery remodeling

Spiral artery remodeling is the process by which the uterine vessels become large bore low resistance conduits, allowing delivery of high volumes of maternal blood to the placenta to nourish the developing fetus. Failure of this process is associated with the pathophysiology of most of the major obstetric complications, including late miscarriage, fetal growth restriction and pre-eclampsia. However, the point at which remodeling 'fails' in these pathological pregnancies is not yet clear. Spiral artery remodeling has predominantly been described in terms of its morphological features, however we are starting to understand more about the cellular and molecular triggers of the different aspects of this process. This review will discuss the current state of knowledge of spiral artery remodeling, in particular the processes involved in loss of the vascular smooth muscle cells, and consider where in the process defects would lead to a pathological pregnancy.

The role of extravillous trophoblasts and uterine NK cells in vascular remodeling during pregnancy

Successful embryo implantation requires both a receptive endometrium and competent blastocysts. After implantation, the maternal decidua undergoes a series of changes, including uterine spiral artery (SA) remodeling to accommodate the fetus and provide nutrients and oxygen for the fetus to survive. Uterine spiral arteries transform from small-diameter, high-resistance arteries to large-diameter and low-resistance arteries during pregnancy. This transformation includes many changes, such as increased permeability and dilation of vessels, phenotypic switching and migration of vascular smooth muscle cells (VSMCs), transient loss of endothelial cells (ECs), endovascular invasion of extravillous trophoblasts (EVTs), and presence of intramural EVT, which are regulated by uterine NK (uNK) cells and EVTs. In this review, we mainly focus on the separate and combined roles of uNK cells and EVTs in uterine SA remodeling in establishing and maintaining pregnancy. New insight into related mechanisms will help us better understand the pathogenesis of pregnancy complications such as recurrent pregnancy loss (RPL) and preeclampsia (PE).

Atrial natriuretic peptide promotes uterine decidualization and a TRAIL-dependent mechanism in spiral artery remodeling

Atrial natriuretic peptide (ANP) is an important hormone in cardiovascular biology. It is activated by the protease corin. In pregnancy, ANP and corin promote uterine spiral artery remodeling, but the underlying mechanism remains unknown. Here we report an ANP function in uterine decidualization and TNF-related apoptosis-inducing ligand-dependent (TRAIL-dependent) death in spiral arterial smooth muscle cells (SMCs) and endothelial cells (ECs). In ANP- or corin-deficient mice, uterine decidualization markers and TRAIL expression were decreased, whereas in cultured human endometrial stromal cells (HESCs), ANP increased decidualization and TRAIL expression. In uterine spiral arteries from pregnant wild-type mice, SMC and EC loss occurred sequentially before trophoblast invasion. In culture, TRAIL from decidualized HESCs induced apoptosis in uterine SMCs, but not in ECs with low TRAIL receptor expression. Subsequently, cyclophilin B was identified from apoptotic SMCs that upregulated endothelial TRAIL receptor and caused apoptosis in ECs. These results indicate that ANP promotes decidualization and TRAIL expression in endometrial stromal cells, contributing to sequential events in remodeling of spiral arteries, including SMC death and cyclophilin B release, which in turn induces TRAIL receptor expression and apoptosis in ECs.

Assessment of Placental Extracellular Vesicles-Associated Fas Ligand and TNF-Related Apoptosis-Inducing Ligand in Pregnancies Complicated by Early and Late Onset Preeclampsia

Preeclampsia (PE) is a hypertensive disorder that affects 2-8% of pregnancies and is one of the main causes of fetal, neonatal, and maternal mortality and morbidity worldwide. Although PE etiology and pathophysiology remain unknown, there is evidence that the hyperactivation of maternal immunity cells against placental cells triggers trophoblast cell apoptosis and death. It has also been reported that placenta-derived extracellular vesicles (EV) carry Fas ligand (FasL) and Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and trigger apoptosis in Jurkat T cells. This study aimed to quantify and compare FasL and TRAIL expression in EV derived from cultures of placenta explants from women with PE (early versus late) and women with uncomplicated pregnancies. Also, the study assessed EV capacity to induce apoptosis in Jurkat T cells. The authors isolated EV from placenta explant cultures, quantified FasL and TRAIL using ELISA, and analyzed EV apoptosis-inducing capability by flow cytometry. Results showed increased FasL and TRAIL in EV derived from placenta of women with PE, and increased EV apoptosis-inducing capability in Jurkat T cells. These results offer supporting evidence that EV FasL and TRAIL play a role in the pathophysiology of PE.

Pathogenesis of uteroplacental acute atherosis: An update on current research

Uteroplacental acute atherosis is a type of arterial vascular disease that affects the placenta during pregnancy and predominates in the maternal spiral arteries in the decidua basalis layer of the pregnant uterus. This condition is characterized by fibrin-like necrosis of the blood vessel walls, the accumulation of macrophages containing fat (foam cells), and the infiltration of macrophages around blood vessels. Uteroplacental acute atherosis is rare in normal pregnancy but occurs more frequently in patients with pregnancy complications, including preeclampsia, spontaneous preterm labor, preterm prelabor rupture of membranes, mid-trimester spontaneous abortion, fetal death, and small-for-gestational age. It is believed that the mechanisms underlying the development of uteroplacental acute atherosis are related to the incomplete physiological transformation of spiral arteries, placental inflammation, abnormal lipid metabolism, and oxidative stress. In this review, we describe the pathogenesis of uteroplacental acute atherosis to provide reference guidelines for the future prevention and treatment of uteroplacental acute atherosclerotic disease.

Pregnant Women Infected with Zika Virus Show Higher Viral Load and Immunoregulatory Cytokines Profile with CXCL10 Increase

BACKGROUND

Zika virus (ZIKV) infection during pregnancy usually shows only mild symptoms and is frequently subclinical. However, it can be vertically transmitted to the fetus, causing microcephaly and other congenital defects. During pregnancy, the immune environment modifications can alter the response to viruses in general and ZIKV in particular.

OBJECTIVE

To describe the role of pregnancy in the systemic pro- and anti-inflammatory response during symptomatic ZIKV infection.

MATERIALS AND METHODS

A multiplex assay was used to measure 25 cytokines, chemokines, and receptors in 110 serum samples from pregnant and nonpregnant women with and without ZIKV infection with and without symptoms. Samples were collected through an epidemiological surveillance system.

RESULTS

Samples from pregnant women with ZIKV infection showed a higher viral load but had similar profiles of inflammatory markers as compared with nonpregnant infected women, except for CXCL10 that was higher in infected pregnant women. Notably, the presence of ZIKV in pregnancy favored a regulatory profile by significantly increasing anti-inflammatory cytokines such as interleukin (IL)-10, receptors IL-1RA, and IL-2R, but only those pro-inflammatory cytokines such as IL-6, interferon (IFN)-α, IFN-γ and IL-17 that are essential for the antiviral response. Interestingly, there were no differences between symptomatic and weakly symptomatic ZIKV-infected groups.

CONCLUSION

Our results revealed a systemic anti-inflammatory cytokine and chemokine profile that could participate in the control of the virus. The anti-inflammatory response in pregnant women infected with ZIKA was characterized by high CXCL10, a cytokine that has been correlated with congenital malformations.

Functional Evaluation of STOX1 (STORKHEAD-BOX PROTEIN 1) in Placentation, Preeclampsia, and Preterm Birth

Revaluation of the association of the STOX1 (STORKHEAD_BOX1 PROTEIN 1) transcription factor mutation (Y153H, C allele) with the early utero-vascular origins of placental pathology is warranted. To investigate if placental STOX1 Y153H genotype affects utero-vascular remodeling-compromised in both preterm birth and preeclampsia-we utilized extravillous trophoblast (EVT) explant and placental decidual coculture models, transfection of STOX1 wild-type and mutant plasmids into EVT-like trophoblast cell lines, and a cohort of 75 placentas from obstetric pathologies. Primary EVT and HTR8/SVneo cells carrying STOX1 Y153H secreted lower levels of IL (interleukin) 6, and IL-8, and higher CXCL16 (chemokine [C-X-C motif] ligand 16) and TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) than wild-type EVT and Swan71 cells. Media from wild-type EVT or Swan71 cells transfected with wild-type STOX1 stimulated: endothelial chemokine expression, angiogenesis, and decidual natural killer cell and monocyte migration. In contrast, Y153H EVT conditioned medium, Swan71 transfected with the Y153H plasmid, or HTR8/SVneo media had no effect. Genotyping of placental decidual cocultures demonstrated association of the placental STOX1 CC allele with failed vascular remodeling. Decidual GG NODAL R165H increased in failed cocultures carrying the placental CC alleles of STOX1. Multivariate analysis of the placental cohort showed that the STOX1 C allele correlated with premature birth, with or without severe early-onset preeclampsia, and small for gestational age babies. In conclusion, placental STOX1 Y153H is a precipitating factor in preterm birth and placental preeclampsia due to defects in early utero-placental development.

Vitamin D Promotes Trophoblast Cell Induced Separation of Vascular Smooth Muscle Cells in Vascular Remodeling via Induction of G-CSF

Vitamin D deficiency is associated with complications of pregnancy such as pre-eclampsia, fetal growth restriction, and miscarriage, all of which are also associated with incomplete spiral artery (SpA) remodeling. We have previously shown that both uterine natural killer (uNK) cells and extravillous trophoblast cells (EVT) are required for successful SpA remodeling, but whether their activity in this process is modulated by vitamin D is not known. In the current study, we use a previously described chorionic plate artery (CPA) ex vivo model of vascular remodeling to determine the effects of 1,25(OH)₂D treated uNK cell, placental explant (PEx), and uNK/PEx conditioned medium (CM) on vascular smooth muscle cell (VSMC) disorganization and phenotypic switching. Significant results were followed up in VSMCs in vitro. We demonstrate that 1,25(OH)₂D can enhance the ability of PEx to induce SpA remodeling, via a mechanism associated with increased secretion of granulocyte-colony stimulating factor (G-CSF). G-CSF appears able to increase VSMC disorganization and phenotypic switching in both an ex vivo vascular model and in vitro VSMC cultures. The clinical relevance of these findings are still to be determined. G-CSF may have differential effects depending on dose and vascular bed, and vitamin D may play a role in potentiating these actions. G-CSF may be an interesting potential therapeutic target for facilitating physiological vascular remodeling for the prevention of adverse obstetric outcomes.

Uterine decidual niche modulates the progressive dedifferentiation of spiral artery vascular smooth muscle cells during human pregnancy†

Uterine spiral artery (SPA) remodeling is a crucial event during pregnancy to provide enough blood supply to maternal-fetal interface and meet the demands of the growing fetus. Along this process, the dynamic change and the fate of spiral artery vascular smooth muscle cells (SPA-VSMCs) have long been debatable. In the present study, we analyzed the cell features of SPA-VSMCs at different stages of vascular remodeling in human early pregnancy, and we demonstrated the progressively morphological change of SPA-VSMCs at un-remodeled (Un-Rem), remodeling, and fully remodeled (Fully-Rem) stages, indicating the extravillous trophoblast (EVT)-independent and EVT-dependent phases of SPA-VSMC dedifferentiation. In vitro experiments in VSMC cell line revealed the efficient roles of decidual stromal cells, decidual natural killer cells (dNK), decidual macrophages, and EVTs in inducing VSMCs dedifferentiation. Importantly, the potential transformation of VSMC toward CD56+ dNKs was displayed by immunofluorescence-DNA in-situ hybridization-proximity ligation and chromatin immunoprecipitation assays for H3K4dime modification in the myosin heavy chain 11 (MYH11) promoter region. The findings clearly illustrate a cascade regulation of the progressive dedifferentiation of SPA-VSMCs by multiple cell types in uterine decidual niche and provide new evidences to reveal the destination of SPA-VSMCs during vascular remodeling.

UDP-glucose, a cellular danger signal, and nucleotide receptor P2Y14 enhance the invasion of human extravillous trophoblast cells

INTRODUCTION

P2Y14, one of the P2Y purinergic G-protein coupled receptors, is expressed in a variety of cells and tissues. Its ligand, UDP-glucose (UDPG), is released from damaged and stress-stimulated cells and acts as a danger signal via P2Y14. Thus, P2Y14 plays an important role in immunological defense systems. Here, we aimed to elucidate the expression, localization, and role of P2Y14 in human trophoblasts and the placenta.

METHODS

Human chorionic villus and placental tissues were subjected to immunostaining for P2Y14 protein and an extravillous trophoblast (EVT) marker, HLA-G. We examined the expression of P2Y14 and the effect of UDPG on cell proliferation and invasion in an EVT cell line, HTR-8/SVneo, using an MTS assay and a Transwell assay, respectively. We tested the effect of UDPG on cell invasion in P2Y14-underexpressing HTR-8/SVneo clones established by the lentiviral introduction of shRNA for P2RY14 mRNA.

RESULTS

Immunostaining revealed that P2Y14 was exclusively expressed by EVTs. P2RY14 mRNA and P2Y14 protein were expressed in HTR-8/SVneo cells. UDPG did not affect cell proliferation but it did enhance invasion. Inhibition of P2Y14 and decreasing the expression of P2Y14 suppressed UDPG-mediated invasive activity.

CONCLUSIONS

These results showed that EVT selectively expressed P2Y14 and that P2Y14 was positively involved in UDPG-enhanced EVT invasion. It suggests the possible existence of a danger signal-mediated physiological system at the fetomaternal interface where UDPG released from maternal tissues through destruction by EVT invasion may accelerate EVT invasion, allowing EVTs to undergo successful placentation and vascular remodeling.

Cyclin G2 Is Involved in the Proliferation of Placental Trophoblast Cells and Their Interactions with Endothelial Cells

Background

Remodeling of maternal spiral arteries after embryo implantation relies on well-regulated trophoblast functions. Although cyclin G2 (CCNG2) is thought to be involved in placental development and function, its role in trophoblasts and the mechanisms underlying placental development and function remain unclear. The present study investigated the potential role of CCNG2 in trophoblast cell proliferation and their interactions with endothelial cells.

Material/Methods

CCNG2 levels were modified by stable infection of HTR8/SVneo cells with lentiviruses overexpressing and silencing CCNG2. Cell proliferation was measured using CCK-8 assays. Network formation assays were performed using trophoblasts alone and co-cultured trophoblasts and endothelial cells to measure angiogenesis of trophoblasts and trophoblast-endothelial interactions. Levels of angiogenic factors (VEGF and sFlt-1) in the supernatant were measured by ELISA, and the expression of cell cycle regulatory (cyclin D1) and invasive (MMP2, MMP3, MMP9) markers implicated in artery remodeling were measured by western blotting.

Results

Ectopic expression of CCNG2 blocked the proliferation of HTR8/SVneo cells, as well as their abilities to form networks and integrate into human umbilical vein endothelial cells, whereas CCNG2 inhibition had the opposite effects. CCNG2 upregulation significantly reduced the expression of VEGF, cyclin D1, MMP2, MMP3, and MMP9, but enhanced the expression of sFlt-1. In contrast, CCNG2 downregulation had the opposite effects.

Conclusions

CCNG2 plays a critical role in trophoblast proliferation and trophoblast-endothelial cell interactions by significant affecting cell cycle, angiogenic, and invasive markers. CCNG2 may thus be a novel marker for the treatment of placental disorders.

Tracking placental development in health and disease

Pre-eclampsia and fetal growth restriction arise from disorders of placental development and have some shared mechanistic features. Initiation is often rooted in the maldevelopment of a maternal-placental blood supply capable of providing for the growth requirements of the fetus in later pregnancy, without exerting undue stress on maternal body systems. Here, we review normal development of a placental bed with a safe and adequate blood supply and a villous placenta-blood interface from which nutrients and oxygen can be extracted for the growing fetus. We consider disease mechanisms that are intrinsic to the maternal environment, the placenta or the interaction between the two. Systemic signalling from the endocrine placenta targets the maternal endothelium and multiple organs to adjust metabolism for an optimal pregnancy and later lactation. This signalling capacity is skewed when placental damage occurs and can deliver a dangerous pathogenic stimulus. We discuss the placental secretome including glycoproteins, microRNAs and extracellular vesicles as potential biomarkers of disease. Angiomodulatory mediators, currently the only effective biomarkers, are discussed alongside non-invasive imaging approaches to the prediction of disease risk. Identifying the signs of impending pathology early enough to intervene and ameliorate disease in later pregnancy remains a complex and challenging objective.

Immune Cells in the Uterine Remodeling: Are They the Target of Endocrine Disrupting Chemicals?

Sufficient uterine remodeling is essential for fetal survival and development. Pathologies related to poor remodeling have a negative impact on maternal and fetal health even years after birth. Research of the last decades yielded excellent studies demonstrating the key role of immune cells in the remodeling processes. This review summarizes the current knowledge about the relevance of immune cells for uterine remodeling during pregnancy and further discusses immunomodulatory effects of man-made endocrine disrupting chemicals on immune cells.

Low oxygen enhances trophoblast column growth by potentiating differentiation of the extravillous lineage and promoting LOX activity

Early placental development and the establishment of the invasive trophoblast lineage take place within a low oxygen environment. However, conflicting and inconsistent findings have obscured the role of oxygen in regulating invasive trophoblast differentiation. In this study, the effect of hypoxic, normoxic and atmospheric oxygen on invasive extravillous pathway progression was examined using a human placental explant model. Here, we show that exposure to low oxygen enhances extravillous column outgrowth and promotes the expression of genes that align with extravillous trophoblast (EVT) lineage commitment. By contrast, supra-physiological atmospheric levels of oxygen promote trophoblast proliferation while simultaneously stalling EVT progression. Low oxygen-induced EVT differentiation coincided with elevated transcriptomic levels of lysyl oxidase (LOX) in trophoblast anchoring columns, in which functional experiments established a role for LOX activity in promoting EVT column outgrowth. The findings of this work support a role for low oxygen in potentiating the differentiation of trophoblasts along the extravillous pathway. In addition, these findings generate insight into new molecular processes controlled by oxygen during early placental development.

MicroRNAs in Uteroplacental Vascular Dysfunction

Pregnancy complications of preeclampsia and intrauterine growth restriction (IUGR) are major causes of maternal and perinatal/neonatal morbidity and mortality. Although their etiologies remain elusive, it is generally accepted that they are secondary to placental insufficiency conferred by both failure in spiral artery remodeling and uteroplacental vascular malfunction. MicroRNAs (miRNAs) are small no-coding RNA molecules that regulate gene expression at the post-transcriptional level. Increasing evidence suggests that miRNAs participate in virtually all biological processes and are involved in numerous human diseases. Differentially expressed miRNAs in the placenta are typical features of both preeclampsia and IUGR. Dysregulated miRNAs target genes of various signaling pathways in uteroplacental tissues, contributing to the development of both complications. In this review, we provide an overview of how aberrant miRNA expression in preeclampsia and IUGR impacts the expression of genes involved in trophoblast invasion and uteroplacental vascular adaptation.

LncRNA MEG3 inhibits trophoblast invasion and trophoblast-mediated VSMC loss in uterine spiral artery remodeling

Extravillous trophoblasts (EVTs) migrate into uterine decidua and induce vascular smooth muscle cell (VSMC) loss through mechanisms thought to involve migration and apoptosis, achieving complete spiral artery remodeling. Long noncoding RNA maternally expressed gene 3 (MEG3) can regulate diverse cellular processes, such as proliferation and migration, and has been discovered highly expressed in human placenta tissues. However, little is known about the role of MEG3 in modulating EVT functions and EVT-induced VSMC loss. In this study, we first examined the location of MEG3 in human first-trimester placenta by in situ hybridization. Then, exogenous upregulation of MEG3 in HTR-8/SVneo cells was performed to investigate the effects of MEG3 on EVT motility and EVT capacity to displace VSMCs. Meanwhile, the molecules mediating EVT-induced VSMC loss, such as tumor necrosis factor-α (TNF-α), Fas ligand (FasL), and tumor necrosis factor-α-related apoptosis-inducing ligand (TRAIL) were detected at transcriptional and translational levels. Finally, VSMCs were cocultured with MEG3-upregulated HTR-8/SVneo to explore the role of MEG3 on EVT-mediated VSMC migration and apoptosis. Results showed that MEG3 was expressed in trophoblasts in placental villi and decidua, and MEG3 enhancement inhibited HTR-8/SVneo migration and invasion. Meanwhile, the displacement of VSMCs by HTR-8/SVneo and the expression of TNF-α, FasL and TRAIL in HTR-8/SVneo were reduced following MEG3 overexpression in HTR-8/SVneo. Furthermore, HTR-8/SVneo with MEG3 upregulation impaired VSMC migration and apoptosis. The PI3K/Akt pathway, which is possibly downstream, was inactivated in MEG3-upregulated HTR-8/SVneo. These findings suggest that MEG3 might be a negative regulator of spiral artery remodeling via suppressing EVT invasion and EVT-mediated VSMC loss.

Lysophosphatidic acid induces the crosstalk between the endovascular human trophoblast and endothelial cells in vitro

Spiral artery remodeling at the maternal-fetal interface is crucial for successful pregnancy and requires the interaction between the first trimester trophoblast and the endothelial cells of the maternal vessels. However, the precise mechanism of this dialog has yet to be determined. The current study investigated whether lysophosphatidic acid (LPA) modulates trophoblast-endothelial crosstalk in vitro. HTR-8/SVneo trophoblast cell line (H8) was seeded on top of Geltrex, incubated with LPA or LPA + NS-398 (selective cyclooxygenase-2 inhibitor), LPA + 1400W (selective inducible nitric oxide synthase inhibitor) or LPA + IL-6 neutralizing antibody and assayed for tube formation to model the acquisition of trophoblast endovascular phenotype. The supernatants were collected and used as conditioned media (CM). To test trophoblast-endothelial crosstalk, the endothelial cell line EA.hy926 was incubated with trophoblast CM. The CM from LPA-induced tubulogenesis stimulated endothelial cells migration and did not modify the apoptosis. Soluble factors derived from cyclooxygenase-2 and IL-6 pathways were involved in H8-EA.hy926 interaction under the LPA effect. Moreover, LPA increased the levels of IL-6 mRNA by cyclooxygenase-2 pathway in H8 cells. Collectively, LPA promotes trophoblast-endothelial crosstalk in vitro and induces the release of trophoblast soluble factors that stimulate endothelial cells migration without changes in apoptosis. The evidence presented here provides new insights about an active role of LPA as a lipid mediator regulating vascular remodeling at the maternal-fetal interface.

Usefulness of uterine artery Doppler velocimetry as a predictor for hypertensive disorders in pregnancy in women with prehypertension before 20 weeks gestation

Hypertensive disorders of pregnancy (HDP) is major complication of maternal-fetal outcomes in obstetric field. Although HDP is mainly defined by high blood pressure, the information about the relationship between prehypertension (preHTN, 120-139mmHg and 80-89mmHg) and HDP development is limited. The objective of this study is to determine the usefulness of preHTN before 20 weeks gestation and uterine artery (UtA) Doppler velocimetry as a predictor of HDP. A total of 2039 singleton pregnant women who had received continuous prenatal care were included in this study. The participants were classified into 2 groups based on the highest blood pressure (BP) under 20 gestational weeks as defined by the Joint National Committee 7: Normotensive (n = 1816) and preHTN pregnant women (n = 223). All preHTN pregnant women were assessed using UtA Doppler velocimetry, and the numbers of preHTN assessments were recorded. The risk of HDP was assessed in the PreHTN groups through patient history and Doppler velocimetry. Compared to normotensive patients, a total of 223 preHTN patients had a higher risk of preeclampsia (OR: 2.3; CI: 1.2-4.3), gestational hypertension (OR: 3.3; CI: 2.0-5.4) and any HDP (OR: 3.0; CI: 2.0-4.5). In the preHTN group, 134 (60.1%) patients had preHTN measured at least twice and 89 (39.9%) patients had preHTN. The results showed that two or more preHTN measurements have high sensitivity for predicting HDP (OR: 1.9; CI: 1.0-3.1; sensitivity: 83.8%; specificity: 47.2%). Additionally, the combination of abnormal UtA Doppler velocimetry results and at least two preHTN measurements showed a high accuracy in predicting HDP (OR: 2.9; CI: 1.1-4.1; sensitivity: 67.6%; specificity: 98.4%). In conclusion, close BP monitoring and recording of every preHTN event are important for pregnant women with preHTN history, and UtA Doppler examination in those women during the 2nd trimester can be a further aid in determining the risk of HDP.

Dysregulated uterine natural killer cells and vascular remodeling in women with recurrent pregnancy losses

PROBLEM

Angiogenesis and vascular remodeling in secretory endometrium represent one of the crucial steps in pregnancy establishment, for which uterine NK (uNK) cells have an important role. Impairment of these steps may proceed to implantation and instigate initial pathology of recurrent pregnancy losses (RPL). In this study, we aim to investigate vascular development and density of uNK cells in secretory endometrium of women with RPL.

METHODS OF STUDY

Mid-secretory phase endometrial tissues from women with RPL (n = 15) and fertile controls (n = 7) were investigated. CD56⁺ and CD16⁺ uNK cells, CD31⁺ vascular endothelial cells and smooth muscle myosin (SMM)⁺ . Vascular smooth muscle cells (VSMC) expressing SMM were investigated using immunohistochemistry and western blot. High-throughput quantitative real-time polymerase chain reaction (qRT-PCR) was used as well.

RESULTS

CD56⁺ uNK number was significantly higher in women with RPL compared to controls (P < 0.0001). uNK cell density by immunohistochemistry was positively correlated with CD56 mRNA expression by qRT-PCR (r²  = 0.43, P = 0.0137). The number of blood vessels represented by the expression of either CD31 or SMM was higher in women with RPL as compared to controls (P < 0.05 and P < 0.0001, respectively), and correlated with the number of uNK cell (r²  = 0.18, P < 0.04, and r²  = 0.65, P < 0.0001, respectively). The wall thickness of spiral arteries was significantly higher in women with RPL as compared with that of controls (P = 0.0027).

CONCLUSION

Increased uNK cells in mid-secretory endometrium are associated with increased vascularization and defective vascular transformation of spiral arteries in women with RPL.

Lower maternal serum tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) levels in early preeclampsia. A retrospective study

OBJECTIVE

To determine whether maternal serum concentrations of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a cytokine with anti-inflammatory activity, also involved in cardiovascular morbidity, differ between women with early preeclampsia (<34 weeks) and those with uncomplicated pregnancies.

STUDY DESIGN

This nested case control study included 40 women carrying a single fetus with an uncomplicated pregnancy and 20 women with early preeclampsia (<34 weeks). Data were matched 1:2 for gestational age at the time of venipuncture (28-34 weeks of gestation), converted into multiples of the median and adjusted for maternal weight. The maternal serum TRAIL concentrations were determined using an enzyme immunoassay.

RESULTS

The TRAIL concentrations were lower in the patients with early preeclampsia when compared with those of the control group, being 29.64 ± 8.83 pg/dL and 43.8 ± 12.53 pg/dL (p-value < 0.001), respectively. The difference was also present after multiple of median conversion and maternal weight adjustment. The quoted multiple of median values were 1.00 ± 0.27 and 0.82 ± 0.23, respectively (p-value < 0.001).

CONCLUSIONS

Serum TRAIL concentrations are significantly reduced in patients with early preeclampsia. This result is in line with the presence of an intravascular inflammation typical of preeclampsia. The lower levels of TRAIL detected in preeclampsia should be useful for a more proper selection of women with long-term cardiovascular risk later in life.

Apoptosis and cell proliferation in porcine placental vascularization

The placenta is a highly vascularized organ, indispensable tothe transfer of nutrients to the growing fetuses. During gestation, there exists an expansion of the placental vascular network through active angiogenesis. The aim of this research was to study cell proliferation and apoptosis through high resolution light microscopy (HRLM) and transmission electron microscopy (TEM) ultrastructure, immunohistochemistry for Ki67and caspase-3, determination of placental vascular area,and TUNEL assay. Crossbred sows placental tissues from approximately 30±2(n=5), 40±2(n=5), 60±2 (n=5), 80±2(n=5), 90±2(n=5) and 114±2(n=5) days of gestation were used. The evaluation of cell proliferation showed the highest%Ki67 values on days 30±2 and 80±2 of pregnancy. Caspase-3 expressed the highest value on day 30±2, while the highest apoptotic indexes were found on days30±2 and 90±2. The placental vascular area was higher on day 80±2 of pregnancy. According to our results, an active vascular cell remodeling by a caspase-3 dependent apoptosis seems to be present in early pregnancy. The increase in the vascular area on day 80±2 would be the result of the intense vascular cell proliferation detected with Ki67. Further studies are needed to understand the complex processes of angiogenesis, cell proliferation and apoptosis that interact in the placenta during porcine gestation.

Effect of Cytokines on the Formation Tube-Like Structures by Endothelial Cells in the Presence of Trophoblast Cells

Despite ample data on cytokine secretion in the uteroplacental interface, the influence of microenvironment cells, in particular, trophoblast cells on angiogenesis and the role of cytokines in this process remain poorly studied. We studied the influence of cytokines on the formation of tube-like structures by endothelial cells in the presence of trophoblast cells and showed that trophoblast cells suppressed the angiogenic potential of endothelial cells. Antiangiogenic cytokines IFN-γ, IL-10, TNF-α, and TGFβ via modulation of trophoblast cells stimulated the formation of tube-like structures by endothelial cells. In the co-culture of endothelial and trophoblast cells, the effects of cytokines changed and they gained additional regulatory functions.

Extravillous Trophoblast and Endothelial Cell Crosstalk Mediates Leukocyte Infiltration to the Early Remodeling Decidual Spiral Arteriole Wall

Decidual spiral arteriole (SpA) remodeling is essential to ensure optimal uteroplacental blood flow during human pregnancy, yet very little is known about the regulatory mechanisms. Uterine decidual NK (dNK) cells and macrophages infiltrate the SpAs and are proposed to initiate remodeling before colonization by extravillous trophoblasts (EVTs); however, the trigger for their infiltration is unknown. Using human first trimester placenta, decidua, primary dNK cells, and macrophages, we tested the hypothesis that EVTs activate SpA endothelial cells to secrete chemokines that have the potential to recruit maternal immune cells into SpAs. Gene array, real-time PCR, and ELISA analyses showed that treatment of endothelial cells with EVT conditioned medium significantly increased production of two chemokines, CCL14 and CXCL6. CCL14 induced chemotaxis of both dNK cells and decidual macrophages, whereas CXCL6 also induced dNK cell migration. Analysis of the decidua basalis from early pregnancy demonstrated expression of CCL14 and CXCL6 by endothelial cells in remodeling SpAs, and their cognate receptors are present in both dNK cells and macrophages. Neutralization studies identified IL-6 and CXCL8 as factors secreted by EVTs that induce endothelial cell CCL14 and CXCL6 expression. This study has identified intricate crosstalk between EVTs, SpA cells, and decidual immune cells that governs their recruitment to SpAs in the early stages of remodeling and has identified potential key candidate factors involved. This provides a new understanding of the interactions between maternal and fetal cells during early placentation and highlights novel avenues for research to understand defective SpA remodeling and consequent pregnancy pathology.

The role of decidual NK cells in pregnancies with impaired vascular remodelling

The pathologies of the dangerous pregnancy complications pre-eclampsia (PE) and fetal growth restriction (FGR) are established in the first trimester of human pregnancy yet we know little of how this happens. Finely tuned interactions between maternal and placental cells are essential for pregnancy to progress without complications; however, the precise nature of this cross-talk and how it can go wrong are crucial questions that remain to be answered. This review summarises recent studies examining the role played by natural killer cells in regulating normal placentation and remodelling. Their involvement when it is impaired in PE/FGR pregnancies will additionally be discussed.

Decidual macrophages: key regulators of vascular remodeling in human pregnancy

Successful remodeling of the uterine spiral arteries is essential for a complication-free pregnancy and is best described in terms of its morphologic features. The molecular mediators and cellular sources of spiral artery remodeling are not known, although a role for uterine leukocytes has been proposed. Immunohistochemical assessment of placental bed biopsies demonstrated uterine NK cells, macrophages, and T lymphocytes in the wall and adventitia of spiral arteries at different stages of remodeling, regardless of the presence of extravillous trophoblast cells. Leukocytes were more prevalent in vessel adventitia than wall, and macrophages were the most abundant leukocyte population. Macrophages, separated from early pregnancy decidua, did not alter extravillous trophoblast cells invasion or vascular smooth muscle cell organization or differentiation status but did induce extracellular matrix breakdown (reduced immunostaining of laminin, P = 0.05; fibronectin, P = 0.02) and were able to phagocytose apoptotic vascular smooth muscle cells. Decidual macrophages were shown to secrete a wide range of cytokines (IL-1β, -2, -4, -5, -6, -8, -10, and -13 and TNF-α), proteases (matrix metalloproteinase-1, -2, -7, -9, and -10), and angiogenic growth factors (angiogenin, keratinocyte growth factor, fibroblast growth factor B, vascular endothelial growth factor A, and angiopoietin-1 and -2). We conclude that spiral artery remodeling involves the coordinated activity of a range of cell types, including extravillous trophoblast cells, decidual uterine NK cells, and macrophages in a carefully, spatiotemporally regulated manner.

Genetic recapitulation of human pre-eclampsia risk during convergent evolution of reduced placental invasiveness in eutherian mammals

The relationship between phenotypic variation arising through individual development and phenotypic variation arising through diversification of species has long been a central question in evolutionary biology. Among humans, reduced placental invasion into endometrial tissues is associated with diseases of pregnancy, especially pre-eclampsia, and reduced placental invasiveness has also evolved, convergently, in at least 10 lineages of eutherian mammals. We tested the hypothesis that a common genetic basis underlies both reduced placental invasion arising through a developmental process in human placental disease and reduced placental invasion found as a derived trait in the diversification of Euarchontoglires (rodents, lagomorphs, tree shrews, colugos and primates). Based on whole-genome analyses across 18 taxa, we identified 1254 genes as having evolved adaptively across all three lineages exhibiting independent evolutionary transitions towards reduced placental invasion. These genes showed strong evidence of enrichment for associations with pre-eclampsia, based on genetic-association studies, gene-expression analyses and gene ontology. We further used in silico prediction to identify a subset of 199 genes that are likely targets of natural selection during transitions in placental invasiveness and which are predicted to also underlie human placental disorders. Our results indicate that abnormal ontogenies can recapitulate major phylogenetic shifts in mammalian evolution, identify new candidate genes for involvement in pre-eclampsia, imply that study of species with less-invasive placentation will provide useful insights into the regulation of placental invasion and pre-eclampsia, and recommend a novel comparative functional-evolutionary approach to the study of genetically based human disease and mammalian diversification.

Function and control of human invasive trophoblast subtypes: Intrinsic vs. maternal control

The establishment of a functional placenta is pivotal for normal fetal development and the maintenance of pregnancy. In the course of early placentation, trophoblast precursors differentiate into highly invasive trophoblast subtypes. These cells, referred to as extravillous trophoblasts (EVTs), penetrate the maternal uterus reaching as far as the inner third of the myometrium. One of the most fundamental functions of EVTs is the transformation of spiral arteries to establish the uteroplacental blood circulation assuring an adequate nutrient and gas supply to the developing fetus. To achieve this, specialized EVT subpopulations interact with maternal immune cells, provoke elastolysis in the arterial wall and replace the endothelial cells lining the spiral arteries to induce intraluminal vascular remodeling. These and other trophoblast-mediated processes are tightly controlled by paracrine signals from the maternal decidua and furthermore underlie an intrinsic cell-type specific program. Various severe pregnancy complications such as preeclampsia or intrauterine growth retardation are associated with abnormal EVT function, shallow invasion, and decreased blood flow to the placenta. Hence a better understanding of human trophoblast invasion seems mandatory to improve therapeutic intervention. This approach, however, requires a profound knowledge of the human placenta, its various trophoblast subtypes and in particular a better understanding of the regulatory network that controls the invasive phenotype of EVTs.

Combined Screening for Early Detection of Pre-Eclampsia

Although the precise pathophysiology of pre-eclampsia remains unknown, this condition continues to be a major cause of maternal and fetal mortality. Early prediction of pre-eclampsia would allow for timely initiation of preventive therapy. A combination of biophysical and biochemical markers are superior to other tests for early prediction of the development of pre-eclampsia. Apart from the use of parameters in first-trimester aneuploidy screening, cell-free fetal DNA quantification is emerging as a promising marker for prediction of pre-eclampsia. This article reviews the current research of the most important strategies for prediction of pre-eclampsia, including the use of maternal risk factors, mean maternal arterial pressure, ultrasound parameters, and biomarkers.

Decidual natural killer cells regulate vessel stability: implications for impaired spiral artery remodelling

Decidual NK (dNK) cells are present during uterine spiral artery remodelling, an event that is crucial for successful placentation and the provision of an adequate blood supply to the developing fetus. Spiral artery remodelling is impaired in the pregnancy complication pre-eclampsia. Although dNK cells are known to play active roles at the maternal-fetal interface, little is known about their effect on endothelial integrity, an important component of vessel stability. We present a study in which we have modelled dNK-endothelium interactions, using first-trimester dNK cells isolated from both normal pregnancies and those with impaired spiral artery remodelling. dNK cells were isolated from first-trimester pregnancies, screened by uterine artery Doppler ultrasound to determine resistance indices (RI) that relate to the extent of spiral artery remodelling. dNK culture supernatant from normal-RI pregnancies (but not high-RI pregnancies) destabilised endothelial tube-like structures in Matrigel, and normal-RI dNK cells induced endothelial intercellular adhesion molecule-1 and tumour necrosis factor-α expression to a greater extent than high-RI dNK cells. We have established a functional role for dNK cells in the disruption of endothelial structures and have suggested how impairment of this process may be contributing to the reduced vessel remodelling in pregnancies with a high uterine artery resistance index. These findings have implications for our understanding of the pathology of pre-eclampsia and other pregnancy disorders where remodelling is impaired.

Inhibition of DDAH1, but not DDAH2, results in apoptosis of a human trophoblast cell line in response to TRAIL

STUDY QUESTION

Does inhibition of dimethylarginine dimethylaminohydrolase (DDAH) increase the sensitivity of trophoblasts to TRAIL-induced apoptosis?

SUMMARY ANSWER

Inhibition of DDAH1, but not DDAH2, increases the sensitivity of trophoblasts to TRAIL-induced apoptosis.

WHAT IS KNOWN ALREADY

Successful human pregnancy is dependent on adequate trophoblast invasion and remodelling of the maternal spiral arteries. Increased trophoblast apoptosis is seen in pregnancies complicated by pre-eclampsia. The mechanism underlying this increase is unknown. We have previously shown that nitric oxide (NO) is involved in regulating trophoblast motility and invasion, and have also demonstrated an important role for NO in regulating trophoblast sensitivity to apoptotic stimuli. DDAH is an enzyme that metabolizes asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthesis, previously shown to be elevated in the plasma of pre-eclamptic mothers.

STUDY DESIGN, SIZE, DURATION

This study used the human extravillous trophoblast-derived cell line SGHPL-4 cells. All experiments were performed at least three times.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The effect of DDAH on trophoblast apoptosis was examined using siRNA and time-lapse microscopy. Changes in the expression of DDAH were followed by PCR and western blot analysis. Receptor expression was followed by flow cytometry.

MAIN RESULTS AND THE ROLE OF CHANCE

Inhibiting the expression of DDAH1, but not DDAH2, resulted in a significant increase in the sensitivity of the EVT cell line SGHPL-4 to tumour necrosis factor related apoptosis inducing ligand (TRAIL) induced apoptosis (P < 0.01). This response could be mimicked by the addition of Asymmetric Dimethylarginine (ADMA), an endogenous inhibitor of NO synthesis and the substrate for both isoforms of DDAH. We further showed that this increased sensitivity to apoptosis is accompanied by a significant increase in the expression of TRAIL receptor 2 (TR2; P < 0.05) but not TRAIL receptor 1 (TR1).

LIMITATIONS, REASONS FOR CAUTION

This study was performed only in vitro using a well characterized trophoblast cell line, SGHPL-4, derived from first trimester extravillous trophoblasts.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides new insight into the role of the DDAH/ADMA pathway in the regulation of trophoblast function. Both dysregulation of DDAH and the accumulation of ADMA have been associated with the development of pre-eclampsia. This is the first study to implicate the DDAH/ADMA pathway as a mechanism that might underlie the poor trophoblast invasion seen in this common pregnancy disorder.

STUDY FUNDING/COMPETING INTEREST(S)

B.A.L. was supported by a grant from Action Medical Research UK (SP4577). A.E.W. was supported by a grant from the Wellcome Trust (091550). There are no competing interests and the authors have no conflict interest to declare.

TRAIL Is Decreased Before 20 Weeks Gestation in Women with Hypertensive Disorders of Pregnancy

Objective

The present study evaluated maternal plasma protein profiles before the onset of hypertensive disorders of pregnancy (HDP) to assess the relationship between maternal plasma tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and HDP before 20 weeks gestation and to evaluate the discriminatory performance of plasma TRAIL levels for HDP.

Methods

A 2-phase discovery/validation study was designed. In the discovery phase, a nested case-controlled study was performed using plasma sampled at 8 to 20 weeks gestation from 20 women who later developed HDP and from 20 age- and gestational week-matched controls. Plasma was analyzed using a human protein microarray technology designed to simultaneously detect 507 proteins. The functional annotation and clustering of the differentially expressed proteins were performed using DAVID and the GO database. TRAIL levels were further validated in an independent study using plasma obtained at 8 to 20 weeks gestation from 53 women who later developed HDP and from 106 matched controls, and 62 clinical risk factors were investigated.

Results

In the protein microarray analysis, 23 proteins were differentially expressed between the two groups. The ELISA showed that women who later developed HDP had significantly lower TRAIL levels compared to women with uncomplicated pregnancies. The multivariable Cox regression analysis identified the following three factors that were entered into the final Cox regression model: gravidity (OR = 2.02, 95% CI 1.00–4.09), pre-pregnancy BMI (OR = 1.46, 95% CI 1.21–1.76) and TRAIL levels (OR = 0.97, 95% CI 0.94–0.99). The model had a significantly better discriminatory power (AUC = 0.83, 95% CI 0.75–0.88) compared to TRAIL alone as an independent predictor of HDP (AUC = 0.59, 95% CI 0.51–0.67).

Conclusion

Twenty-three differentially expressed proteins before 20 weeks gestation might be associated with the pathogenesis of HDP. Plasma TRAIL levels were associated with the development of HDP, and the combination of plasma TRAIL levels with pre-pregnancy BMI and gravidity had a good discriminatory performance for HDP before 20 weeks gestation.

The role of apoptosis in human embryo implantation

The process of embryo attachment and invasion through the endometrial epithelial cells and subsequent implantation into the decidualized endometrial stroma is the groundbreaking step for the establishment of a successful pregnancy. Necessary prerequisites are a receptive endometrium, a good-quality embryo and a well-orchestrated molecular dialog between embryo and maternal endometrium. The embryo-maternal dialog is conducted via a wide scope of factors, including secreted cytokines, chemokines, and growth factors in addition to the expression of corresponding receptors and co-receptors. Several embryonic proteins, including the aforementioned, are involved in the process of apoptosis, which necessarily needs to take place at the maternal endometrium to allow the embryo to invade. The endometrial epithelium is thereby disintegrated completely within a particular area, whereas the endometrial stroma seems to require a more depth-limited apoptosis. As of today, the exact mechanisms and factors mediating the apoptotic process involved in those apparently differently regulated incidents are not fully understood, particularly with regard to stromal cell apoptosis. There is evidence though, that cytokines and their respective receptors play a major role. A suggested important co-receptor for cytokines, which is highly upregulated in the receptive human endometrium, is the heparan sulfate proteoglycan syndecan-1. It is present on the cell surface and involved in the regulation of cell-cell-interaction, cell binding, cell signaling and cytoskeletal organization and therefore represents a possible mediator of apoptosis regulation in human endometrium. Herein, the literature on endometrial epithelial and stromal apoptosis in general, and in light of the influence of syndecan-1, is reviewed.

Increased angiogenic factor secretion by decidual natural killer cells from pregnancies with high uterine artery resistance alters trophoblast function

STUDY QUESTION

Are the concentrations of factors secreted by decidual natural killer (dNK) cells from pregnancies at high risk of poor spiral artery remodelling different to those secreted from pregnancies at low risk?

SUMMARY ANSWER

Expression levels of PLGF, sIL-2R, endostatin and angiogenin were significantly increased by dNK cells from high-risk pregnancies, and angiogenin and endostatin were found to alter trophoblast function.

WHAT IS KNOWN ALREADY

During early pregnancy, maternal uterine spiral arteries are remodelled from small diameter, low-flow, high-resistance vessels into larger diameter, higher flow vessels, with low-resistance. This change is essential for the developing fetus to obtain sufficient oxygen and nutrients. dNK cells have been implicated in this process.

STUDY DESIGN, SIZE, DURATION

dNK cells were isolated from first trimester terminations of pregnancies (obtained with local ethical approval) screened for normal- or high-resistance index, indicative of cases least (<1%) and most (>21%) likely to have developed pre-eclampsia had the pregnancy not been terminated (n = 18 each group). Secreted factors and the effects of these on the trophoblast cell line, SGHPL-4, were assessed in vitro.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A multiplex assay was used to assess dNK cell-secreted factors. SGHPL-4 cell functions were assessed using time-lapse microscopy, 3D invasion assays, endothelial-like tube formation ability and western blot analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

The expression levels of PLGF (P < 0.01), sIL-2R (P < 0.01), endostatin (P < 0.05) and angiogenin (P < 0.05) were significantly increased by dNK cells from high-risk pregnancies. Endostatin significantly decreased SGHPL-4 invasion (P < 0.05), SGHPL-4 tube formation (P < 0.05) and SGHPL-4 Akt^ser473 phosphorylation (P < 0.05). Angiogenin significantly decreased SGHPL-4 invasion (P < 0.05), but increased SGHPL-4 tube formation (P < 0.01) and decreased SGHPL-4 Akt^ser473 phosphorylation (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

The culture of dNK cells and protein concentrations in vitro may not fully represent the in vivo situation. Although SGHPL-4 cells are extravillous trophoblast derived, further studies would be needed to confirm the roles of angiogenin and endostatin in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

The altered expression of secreted factors of dNK cells may contribute to pregnancy disorders associated with poor spiral artery remodelling.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Wellcome Trust (project reference 091550). R.F. was a recipient of a PhD studentship from the Division of Biomedical Sciences, St. George's, University of London. The authors have no conflict of interests.

Notch signaling plays a critical role in motility and differentiation of human first-trimester cytotrophoblasts

Failures in human extravillous trophoblast (EVT) development could be involved in the pathogenesis of pregnancy diseases. However, the underlying mechanisms have been poorly characterized. Here, we provide evidence that Notch signaling could represent a key regulatory pathway controlling trophoblast proliferation, motility, and differentiation. Immunofluorescence of first-trimester placental tissues revealed expression of Notch receptors (Notch2 and Notch3) and membrane-anchored ligands (delta-like ligand [DLL] 1 and -4 and Jagged [JAG] 1 and -2) in villous cytotrophoblasts (vCTBs), cell column trophoblasts (CCTs), and EVTs. Notch4 and Notch1 were exclusively expressed in vCTBs and in CCTs, respectively. Both proteins decreased in Western blot analyses of first-trimester, primary cytotrophoblasts (CTBs) differentiating on fibronectin. Luciferase reporter analyses suggested basal, canonical Notch activity in SGHPL-5 cells and primary cells that was increased upon seeding on DLL4-coated dishes and diminished in the presence of the Notch/γ-secretase inhibitors N-[N-(3,5-difluorophenacetyl-l-alanyl)]-S-phenylglycine t-butyl ester (DAPT) or L-685,458. Bromodeoxyuridine labeling, cyclin D1 mRNA expression, and cell counting indicated that chemical inhibition of Notch signaling elevated proliferation in the different primary trophoblast model systems. Notch inhibition also increased motility of SGHPL-5 cells through uncoated and fibronectin-coated Transwells, motility of primary CTBs, as well as migration in villous explant cultures on collagen I. Accordingly, small interfering RNA-mediated gene silencing of Notch1 also elevated SGHPL-5 cell migration. In contrast, motility of primary cultures and SGHPL-5 cells was diminished in the presence of DLL4. Moreover, DAPT increased markers of differentiated EVT, ie, human leukocyte antigen G1, integrin α5, and T-cell factor 4, whereas DLL4 provoked the opposite. In summary, the data suggest that canonical Notch signaling impairs motility and differentiation of first-trimester CTBs.

Decidual natural killer cell interactions with trophoblasts are impaired in pregnancies at increased risk of preeclampsia

Transformation of the uterine spiral arteries (SAs) during pregnancy is critical to support the developing fetus, and is impaired in some pregnancy disorders, including preeclampsia. Decidual natural killer (dNK) cells play a role in SA remodeling, although their interactions with fetal trophoblast remain unclear. A uterine artery Doppler resistance index (RI) in the first trimester of pregnancy can be used as a proxy measure of the extent of SA remodeling; we have used this technique to characterize dNK cells from pregnancies with normal (normal RI) and impaired (high RI) SA remodeling, which display least and highest risk of developing preeclampsia, respectively. We examined the impact of dNK cell secreted factors on trophoblast motility, chemoattraction, and signaling pathways to determine the contribution of dNK cells to SA transformation. We demonstrated that the chemoattraction of the trophoblast by dNK cells is impaired in pregnancies with high RI, as is the ability to induce trophoblast outgrowth from placental villous explants. These processes are dependent on activation of the extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3-kinase-Akt signaling pathways, which were altered in trophoblasts incubated with secreted factors from dNK cells from high RI pregnancies. Therefore, by characterizing pregnancies using uterine artery Doppler RI before dNK cell isolation, we have identified that impaired dNK-trophoblast interactions may lead to poor placentation. These findings have implications for pregnancy pathological conditions, such as preeclampsia.

Maternal plasma soluble TRAIL is decreased in preeclampsia

OBJECTIVE

Preeclampsia (PE) is characterized by systemic intravascular inflammation. Women who develop PE are at an increased risk for cardiovascular disease in later life. Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) has anti-atherosclerotic effects in endothelial cells and can mediate neutrophil apoptosis. Low soluble TRAIL (sTRAIL) and high C-reactive protein (CRP) concentrations are associated with an increased risk of future cardiovascular disease in non-pregnant individuals. The aim of this study was to determine whether maternal plasma concentrations of sTRAIL and CRP differ between women with PE and those with uncomplicated pregnancies.

METHOD

This cross-sectional study included women with an uncomplicated pregnancy (n = 93) and those with PE (n = 52). Maternal plasma concentrations of sTRAIL and CRP concentrations were determined by ELISA.

RESULTS

1) The median plasma sTRAIL concentration (pg/mL) was significantly lower and the median plasma CRP concentration was significantly higher in women with PE than in those with an uncomplicated pregnancy (25.55 versus 29.17; p = 0.03 and 8.0 versus 4.1; p = 0.001, respectively); 2) the median plasma concentration sTRAIL/CRP ratio was two-fold lower in women with PE than in those with an uncomplicated pregnancy (p < 0.001); and 3) women with plasma sTRAIL and CRP ratio in the lowest quartile were 8 times more likely to have PE than women with concentrations in the upper three quartiles (OR 8.9; 95% CI: 2.8-27.8).

CONCLUSION

Maternal plasma sTRAIL concentrations are lower (while those of CRP are higher) in women with PE than in those with uncomplicated pregnancies. These findings are consistent with the evidence of intravascular inflammation in this disorder.

Baseline TNFα operational capacity in fetal and maternal circulation prior to the onset of labor: "tuned for different purposes"

OBJECTIVE

In this study, we sought to characterize the tumor necrosis factor α (TNFα) baseline operational capacity in mature fetuses and their mothers prior to the onset of labor.

MATERIALS AND METHODS

We used an experimental pregnant nonhuman primate model to measure the plasma concentration of TNFα, TNF transmembrane receptor I (TNFRI), and TNFRII with validated enzyme-linked immunosorbent assays. Coefficients of correlations between the maternal and the fetal values and the soluble TNFα, TNFRI, or TNFRII concentrations and ratios were calculated.

RESULTS

The TNFα/TNFRI ratio was 3 times lower in fetal circulation than in maternal circulation. No correlations were noted between the maternal and the fetal TNFα, TNFRI, or TNFRII plasma concentrations.

CONCLUSIONS

These findings suggest that the fetal and maternal baseline circulatory operational capacities of TNFα are independent of each other and tuned differently. This differential regulation of TNFα in fetal and maternal circulation at the end of pregnancy may be guided to protect the fetus from the systemic inflammatory response that is essential for the mechanisms of labor to proceed in the mother.

Soluble TRAIL in normal pregnancy and acute pyelonephritis: a potential explanation for the susceptibility of pregnant women to microbial products and infection

OBJECTIVE

Pregnancy is characterized by activation of the innate immune response demonstrated by phenotypic and metabolic changes in granulocytes and monocytes. This state of activation has been implicated in the pathophysiology of multiorgan dysfunction of pregnant women with acute viral or bacterial infection. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is one of the mediators responsible for neutrophil apoptosis. Gene deletion of TRAIL results in delayed neutrophil apoptosis and resolution of inflammation after the administration of bacterial endotoxin. The aim of this study was to determine whether maternal plasma concentrations of the soluble form of TRAIL (sTRAIL) differ in women with uncomplicated pregnancy and those with acute pyelonephritis.

METHOD

A cross-sectional study was conducted to include women in the following groups: (1) non-pregnant (n = 23); (2) uncomplicated pregnancies (n = 93) and (3) pregnancies with acute pyelonephritis (n = 23). Plasma concentrations of sTRAIL were determined by enzyme-linked immunoassay.

RESULTS

(1) Women with uncomplicated pregnancies had a lower mean plasma sTRAIL concentration (pg/mL) than non-pregnant women (31.5 ± 10.1 versus 53.3 ± 12.5; p < 0.001); (2) plasma sTRAIL concentrations did not change as a function of gestational age (Pearson correlation = -0.1; p = 0.4); (3) the mean plasma sTRAIL concentration (pg/mL) was significantly lower in pregnant women with acute pyelonephritis than in those with uncomplicated pregnancies (20.5 ± 6.6 versus 31.5 ± 10.1; p < 0.001) and (4) among patients with acute pyelonephritis, patients with bacteremia had a significantly lower mean plasma concentration of sTRAIL (pg/mL) than those without bacteremia (15.1 ± 4.8 versus 24.7 ± 4.6; p < 0.001).

CONCLUSION

Women with uncomplicated pregnancies are associated with a significantly lower mean maternal plasma concentration of sTRAIL than that observed in non-pregnant women. Moreover, a further decrease in plasma sTRAIL concentration was observed in pregnant women with acute pyelonephritis, and this could account, at least in part, for the exaggerated intravascular inflammatory response previously reported in pyelonephritis during pregnancy.