The Impact of Preeclampsia on Gene Expression at the Maternal-Fetal Interface

Advancing diagnosis and early risk assessment of preeclampsia through noninvasive cell-free DNA methylation profiling

BACKGROUND

Aberrant embryo implantation and suboptimal placentation can lead to (severe) complications such as preeclampsia and fetal growth restriction later in pregnancy. Current identification of high-risk pregnancies relies on a combination of risk factors, biomarkers, and ultrasound examinations, a relatively inaccurate approach. Previously, aberrant DNA methylation due to placental hypoxia has been identified as a potential marker of placental insufficiency and, hence, potential (future) pregnancy complications. The goal of the Early Prediction of prEgnancy Complications Testing, or the ExPECT study, is to validate a genome-wide, cell-free DNA (cfDNA) methylation strategy to diagnose preeclampsia accurately. More importantly, the predictive potential of this strategy is also explored to reliably identify high-risk pregnancies early in gestation. Furthermore, a longitudinal study was conducted, including sequential blood samples from pregnant individuals experiencing both uneventful and complicated gestations, to assess the methylation dynamics of cfDNA throughout these pregnancies. A significant strength of this study is its enzymatic digest, which enriches CpG-rich regions across the genome without the need for proprietary reagents or prior selection of regions of interest. This makes it useful for the cost-effective discovery of novel markers.

RESULTS

Investigation of methylation patterns throughout pregnancy showed different methylation trends between unaffected and affected pregnancies. We detected differentially methylated regions (DMRs) in pregnancies complicated with preeclampsia as early as 12 weeks of gestation, with distinct differences in the methylation profile between early and late pregnancy. Two classification models were developed to diagnose and predict preeclampsia, demonstrating promising results on a small set of validation samples.

CONCLUSIONS

This study offers valuable insights into methylation changes at specific genomic regions throughout pregnancy, revealing critical differences between normal and complicated pregnancies. The power of noninvasive cfDNA methylation profiling was successfully proven, suggesting the potential to integrate this noninvasive approach into routine prenatal care.

Extracellular Matrix Influences Gene Expression and Differentiation of Mouse Trophoblast Stem Cells

Trophoblast stem (TS) cells were first isolated from the mouse placenta; however, little is known about their maintenance and niche in vivo. TS cells, like other stem cells, have a unique microenvironment in which the extracellular matrix (ECM) is a component. Placental pathology is associated with ECM change. However, how these changes and the individual ECM components impact the maintenance or differentiation of TS cells has not been established. This study identified which ECM component(s) maintain the greatest expression of markers associated with undifferentiated mouse trophoblast stem (mTS) cells and which alter the profile of markers of differentiation based on mRNA analysis. mTS cells cultured on individual ECM components and subsequent quantitative polymerase chain reaction analysis revealed that laminin promoted the expression of markers associated with undifferentiated TS cells, fibronectin promoted gene expression associated with syncytiotrophoblast (SynT) layer II cells, and collagen IV promoted the expression of genes associated with differentiated trophoblast. To investigate whether pathological placental ECM influenced the expression of genes associated with different trophoblast subtypes, the mouse model of streptozotocin (STZ)-induced pancreatic β cell ablation and diabetes was used. Female mice administered STZ (blood glucose ≥300 mg/dL) or control (blood glucose ≤150 mg/dL) were mated. Placental pathology at embryonic day (E)14.5 was confirmed with reduced fetal blood space area, reduced expression of the pericyte marker αSMA, and decreased expression of ECM proteins. mTS cells cultured on ECM isolated from STZ placenta were associated with reduced expression of undifferentiated mTS markers and increased expression of genes associated with terminally differentiated trophoblast [Gcm-1 and SynA (SynT) and junctional zone Tpbpa and Prl2c2]. Altogether, these results support the value of using ECM isolated from the placenta as a tool for understanding trophoblast contribution to placental pathology.

Decidualization resistance in the origin of preeclampsia

Preeclampsia is a major obstetrical complication with short- and long-term life-threatening consequences for both mother and child. Shallow cytotrophoblast invasion through the uterine decidua into the spiral arteries is implicated in the pathogenesis of preeclampsia, although the cause of deficient arterial invasion remains unknown. Research that is focused on the "soil"-the maternal decidua-highlights the importance of this poorly understood but influential uterine layer. Decidualization of endometrial cells regulates embryo invasion, which is essential for spiral artery remodeling and establishing the maternal-fetal interface. Exploration of the association between impaired decidualization and preeclampsia revealed suboptimal endometrial maturation and uterine natural killer cells present in the decidua before preeclampsia development. Furthermore, decidualization defects in the endometrium of women with severe preeclampsia, characterized by impaired cytotrophoblast invasion, were detected at the time of delivery and persisted 5 years after the affected pregnancy. Recently, a maternal deficiency of annexin A2 expression was found to influence aberrant decidualization and shallow cytotrophoblast invasion, suggesting that decidualization resistance, which is a defective endometrial cell differentiation during the menstrual cycle, could underlie shallow trophoblast invasion and the poor establishment of the maternal-fetal interface. Based on these findings, the transcriptional signature in the endometrium that promotes decidualization deficiency could be detected before (or after) conception. This would serve to identify women at risk of developing severe preeclampsia and aid the development of therapies focused on improving decidualization, perhaps also preventing severe preeclampsia. Here, we discuss decidualization deficiency as a contributor to the pathogenesis of pregnancy disorders with particular attention to severe preeclampsia. We also review current diagnostic strategies and discuss future directions in diagnostic methods based on decidualization.

Transcription Factor PLAGL1 Is Associated with Angiogenic Gene Expression in the Placenta

During pregnancy, the placenta is important for transporting nutrients and waste between the maternal and fetal blood supply, secreting hormones, and serving as a protective barrier. To better understand placental development, we must understand how placental gene expression is regulated. We used RNA-seq data and ChIP-seq data for the enhancer associated mark, H3k27ac, to study gene regulation in the mouse placenta at embryonic day (e) 9.5, when the placenta is developing a complex network of blood vessels. We identified several upregulated transcription factors with enriched binding sites in e9.5-specific enhancers. The most enriched transcription factor, PLAGL1 had a predicted motif in 233 regions that were significantly associated with vasculature development and response to insulin stimulus genes. We then performed several experiments using mouse placenta and a human trophoblast cell line to understand the role of PLAGL1 in placental development. In the mouse placenta, Plagl1 is expressed in endothelial cells of the labyrinth layer and is differentially expressed in placentas from mice with gestational diabetes compared to placentas from control mice in a sex-specific manner. In human trophoblast cells, siRNA knockdown significantly decreased expression of genes associated with placental vasculature development terms. In a tube assay, decreased PLAGL1 expression led to reduced cord formation. These results suggest that Plagl1 regulates overlapping gene networks in placental trophoblast and endothelial cells, and may play a critical role in placental development in normal and complicated pregnancies.

Glycosylated Siglec-6 expression in syncytiotrophoblast-derived extracellular vesicles from preeclampsia placentas

INTRODUCTION

Preeclampsia (PE) is associated with an exaggerated maternal systemic inflammatory response. Throughout gestation, the placenta releases extracellular vesicles through the syncytiotrophoblast layer (STB) into the maternal circulation and this is increased in PE. Expression of Siglec-6, a transmembrane receptor of molecular weight 50 KDa, is upregulated in PE placental tissue.

METHODS

Here we investigated respective abundance of Siglec-6 in PE -and normal pregnancy- (NP) derived placental lysates (PL) and syncytiotrophoblast-derived extracellular vesicles (STBEV). STBEV from PE and NP placentas were isolated through dual-lobe placental perfusion and serial ultracentrifugation. Siglec-6 was characterized by immunohistochemistry, immunoblotting, mass spectrometry (MS), and deglycosylation.

RESULTS

Immunoblotting revealed the expected Siglec-6 (50 KDa) band present in both PE and NP PL, however an additional heavier band was observed at 70 KDa only in PE PL, but not in NP. When interrogating STBEV we saw an absence of the expected 50 KDa band but the 70 KDa was present predominantly only in the PE STBEV. Deglycosylation of PL and STBEV from PE showed that the 70 KDa and the 50 KDa bands were reduced to 48 KDa, suggesting glycosylation. Both 48 KDa and 70 KDa bands were subjected to MS, confirming Siglec-6 expression in both.

DISCUSSION

Our data shows that the inability to detect Siglec-6 in circulation might be due to the placenta secreting STBEV carrying a modified glycosylated form of Siglec-6 with a 70 KDa molecular weight, significantly and uniquely upregulated in PE STBEV.

Laminins Regulate Placentation and Pre-eclampsia: Focus on Trophoblasts and Endothelial Cells

Pre-eclampsia is a systemic vascular disease characterized by new-onset hypertension and/or proteinuria at ≥20 weeks of gestation and leads to high rates of maternal and perinatal morbidity and mortality. Despite the incomplete understanding of pre-eclampsia pathophysiology, it is accepted that insufficient spiral artery remodeling and endothelial dysfunction are major contributors. Laminins (LNs) are a vital family of extracellular matrix (ECM) molecules present in basement membranes that provide unique spatial and molecular information to regulate implantation and placentation. LNs interact with cell surface receptors to trigger intracellular signals that affect cellular behavior. This mini-review summarizes the role of LNs in placental development during normal pregnancy. Moreover, it describes how LN deficiency can lead to the pre-eclampsia, which is associated with trophoblast and vascular endothelial dysfunction. New research directions and the prospect of clinical diagnosis of LN deficiency are discussed, and the gaps in basic and clinical research in this field are highlighted.

MMP-9 and TIMP-1 in placenta of hypertensive disorder complicating pregnancy

Expression and characteristics of matrix metalloproteinase-9 (MMP-9) and TIMP metallopeptidase inhibitor-1 (TIMP-1) in the placenta of pregnancy induced hypertension (PIH) were detected in Uygur to analyze its correlation with PIH, and to provide a theoretical basis for clinical work. Ninety cases of placental tissue patients who were hospitalized in the Department of Obstetrics of People's Hospital of Xinjiang Uygur from December 2014 to September 2016 were collected, including 30 cases of severe preeclampsia, 30 cases of mild preeclampsia, and 30 cases of normal group. The distribution of MMP-9 and TIMP-1 in placenta was mainly in the cytoplasm of trophoblast cells, vascular endothelial cells and villous mesenchymal cells. The distribution of MMP-9 positive particles in the placenta tissue of the severe group was significantly reduced. The difference of MMP-9 in the three groups was statistically significant. Severe group was statistically significantly different from normal and mild group. With the aggravation of PIH, positive expression of MMP-9 was gradually decreased. TIMP-1 was expressed in each group, and difference was not statistically significant. Positive expression ratio of MMP-9/TIMP-1 in severe group was lower than that in normal pregnancy and mild group, and positive expression ratio of the two groups became smaller as the condition worsened. Positive expression of MMP-9 in placental tissue of patients with PIH decreased significantly with the severity of PIH. TIMP-1 in placental tissue of PIH patients did not change much in each group, and had no significant correlation with PIH.

Placental basement membrane proteins are required for effective cytotrophoblast invasion in a three-dimensional bioprinted placenta model

Fetal cytotrophoblast invasion of maternal decidual vasculature is necessary to normal pregnancy. In preeclampsia, there is shallow invasion and abnormal remodeling of the uterine vasculature that lead to significant maternal and perinatal morbidity and mortality. The placental basement membrane (BM) proteins (e.g., laminin and collagen) has been implicated in the development of placenta while the level of laminin is significantly lower in preeclampsia. However, there are very limited studies, if any, on the effect of extracellular matrix (ECM) microenvironment on the invasion of cytotrophoblast. In this study, we hypothesized that placental BM proteins are required for effective cytotrophoblast invasion. Using proteomics, we found that more than 80% of ECM proteins in placental basal plate (pECM) were BM proteins. In addition to upregulating expressions of MMP2 (1.5-fold) and MMP9 (6.3-fold), pECM significantly increased the motility rates of cytotrophoblasts by 13-fold (from 5.60 ± 0.95 to 75.5 ± 21.8 µm/day) to achieve an effective invasion rate that was comparable to in vivo results. Treatments with PI3K inhibitors completely removed the pECM-enhanced invasive phenotypes and genotypes of cytotrophoblasts, suggesting its dominant role in cytotrophoblast-ECM interactions. Our results described, for the first time, the substantial effects of the ECM microenvironment on regulating cytotrophoblast invasion, an area that is less investigated but appear to be critical in the pathogenesis of preeclampsia. Moreover, the approach presented in this work that fabricates organ models with organ-specific ECM can be an attractive option to screen and develop novel therapeutics and biomarkers not only in preeclampsia but also other diseases such as cancer metastasis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1476-1487, 2018.

Upregulation of MiR-29b contributes to mesenchymal stem cell dysfunction in patients with severe pre-eclampsia

The aim of this study was to investigate the role of miR-29b in the regulation of decidua-derived mesenchymal stem cells (dMSCs) to influence the pathogenesis of pre-eclampsia (PE). dMSCs were isolated from decidua tissue and characterized. The expression of miRNAs was evaluated by quantitative PCR. Overexpression and inhibition of miR-29b were achieved in dMSCs, and the effect of miR-29b overexpression on the migration and angiogenic potential of human umbilical vein endothelial cells (HUVEC) was assessed. Furthermore, we performed bioinformatic analyses, luciferase reporter gene assays, and gene expression analyses to identify the potential targets of miR-29b and to verify the effect of target genes on dMSC function. Upregulation of miR-29b was confirmed in severe PE patients. Overexpression of miR-29b attenuated cell proliferation of dMSCs. Overexpression of miR-29b in dMSCs decreased the migratory and tubule formation ability of HUVECs. Histone deacetylase 4 (HDAC4) was identified as a target gene of miR-29b. Decreased migration and tubule formation in HUVECs was observed upon incubation with conditioned medium from dMSCs treated with the HDAC inhibitor trichostatin A. Our results demonstrated that upregulation of miR-29b in dMSCs has an important paracrine effect and might be involved in the development of PE.

Defective decidualization during and after severe preeclampsia reveals a possible maternal contribution to the etiology

In preeclampsia (PE), cytotrophoblast (CTB) invasion of the uterus and spiral arteries is often shallow. Thus, the placenta's role has been a focus. In this study, we tested the hypothesis that decidual defects are an important determinant of the placental phenotype. We isolated human endometrial stromal cells from nonpregnant donors with a previous pregnancy that was complicated by severe PE (sPE). Compared with control cells, they failed to decidualize in vitro as demonstrated by morphological criteria and the analysis of stage-specific antigens (i.e., IGFBP1, PRL). These results were bolstered by global transcriptional profiling data that showed they were transcriptionally inert. Additionally, we used laser microdissection to isolate the decidua from tissue sections of the maternal-fetal interface in sPE. Global transcriptional profiling revealed defects in gene expression. Also, decidual cells from patients with sPE, which dedifferentiated in vitro, failed to redecidualize in culture. Conditioned medium from these cells failed to support CTB invasion. To mimic aspects of the uterine environment in normal pregnancy, we added PRL and IGFBP1, which enhanced invasion. These data suggested that failed decidualization is an important contributor to down-regulated CTB invasion in sPE. Future studies will be aimed at determining whether this discovery has translational potential with regard to assessing a woman's risk of developing this pregnancy complication.

Emerging role for dysregulated decidualization in the genesis of preeclampsia

In normal human placentation, uterine invasion by trophoblast cells and subsequent spiral artery remodeling depend on cooperation among fetal trophoblasts and maternal decidual, myometrial, immune and vascular cells in the uterine wall. Therefore, aberrant function of anyone or several of these cell-types could theoretically impair placentation leading to the development of preeclampsia. Because trophoblast invasion and spiral artery remodeling occur during the first half of pregnancy, the molecular pathology of fetal placental and maternal decidual tissues following delivery may not be informative about the genesis of impaired placentation, which transpired months earlier. Therefore, in this review, we focus on the emerging prospective evidence supporting the concept that deficient or defective endometrial maturation in the late secretory phase and during early pregnancy, i.e., pre-decidualization and decidualization, respectively, may contribute to the genesis of preeclampsia. The first prospectively-acquired data directly supporting this concept were unexpectedly revealed in transcriptomic analyses of chorionic villous samples (CVS) obtained during the first trimester of women who developed preeclampsia 5 months later. Additional supportive evidence arose from investigations of Natural Killer cells in first trimester decidua from elective terminations of women with high resistance uterine artery indices, a surrogate for deficient trophoblast invasion. Last, circulating insulin growth factor binding protein-1, which is secreted by decidual stromal cells was decreased during early pregnancy in women who developed preeclampsia. We conclude this review by making recommendations for further prospectively-designed studies to corroborate the concept of endometrial antecedents of preeclampsia. These studies could also enable identification of women at increased risk for developing preeclampsia, unveil the molecular mechanisms of deficient or defective (pre)decidualization, and lead to preventative strategies designed to improve (pre)decidualization, thereby reducing risk for preeclampsia development.

Matrix metalloproteinase multiplex screening identifies increased MMP-2 urine concentrations in women predicted to develop preeclampsia

BACKGROUND

Preeclampsia, a pregnancy disorder characterized by hypertension and proteinuria, represents the leading cause of fetal and maternal morbidity and mortality in developing countries. The identification of novel and accurate biomarkers that are predictive of preeclampsia is necessary to improve the prognosis of patients with preeclampsia.

OBJECTIVE

The objective of this study is to evaluate the usefulness of nine urinary metalloproteinases to predict the risk of preeclampsia development.

METHODS

MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12 and MMP-13 were analyzed in urine (early-pregnancy) from 17 women predicted to develop preeclampsia and 48 controls using the Bio-Plex Pro-Human MMP panel (Bio-Rad, Hercules, CA).

RESULTS

Urinary MMP-2 showed differences between groups which allowed us to calculate an increased risk for PE development of up to 20 times among the study population.

CONCLUSION

Increased urinary concentration of MMP-2 at 12 and 16 weeks of gestation predicted an increased risk of developing preeclampsia in the study population.

Why is placentation abnormal in preeclampsia?

The causes of preeclampsia remain one of the great medical mysteries of our time. This syndrome is thought to occur in 2 stages with abnormal placentation leading to a maternal inflammatory response. Specific regions of the placenta have distinct pathologic features. During normal pregnancy, cytotrophoblasts emigrate from the chorionic villi and invade the uterus, reaching the inner third of the myometrium. This unusual process is made even more exceptional by the fact that the placental cells are hemiallogeneic, coexpressing maternal and paternal genomes. Within the uterine wall, cytotrophoblasts deeply invade the spiral arteries. Cytotrophoblasts migrate up these vessels and replace, in a retrograde fashion, the maternal endothelial lining. They also insert themselves among the smooth muscle cells that form the tunica media. As a result, the spiral arteries attain the physiologic properties that are required to perfuse the placenta adequately. In comparison, invasion of the venous side of the uterine circulation is minimal, sufficient to enable venous return. In preeclampsia, cytotrophoblast invasion of the interstitial uterine compartment is frequently shallow, although not consistently so. In many locations, spiral artery invasion is incomplete. There are many fewer endovascular cytotrophoblasts, and some vessels retain portions of their endothelial lining with relatively intact muscular coats, although others are not modified. Work from our group showed that these defects mirror deficits in the differentiation program that enables cytotrophoblast invasion of the uterine wall. During normal pregnancy, invasion is accompanied by the down-regulation of epithelial-like molecules that are indicative of their ectodermal origin and up-regulation of numerous receptors and ligands that typically are expressed by endothelial or vascular smooth muscle cells. For example, the expression of epithelial-cadherin (the cell-cell adhesion molecule that many ectodermal derivatives use to adhere to one another) becomes nearly undetectable, replaced by vascular-endothelial cadherin, which serves the same purpose in blood vessels. Invading cytotrophoblasts also modulate vascular endothelial growth factor ligands and receptors, at some point in the differentiation process expressing every (mammalian) family member. Molecules in this family play crucial roles in vascular and trophoblast biology, including the prevention of apoptosis. In preeclampsia, this process of vascular mimicry is incomplete, which we theorize hinders the cells interactions with spiral arterioles. What causes these aberrations? Given what is known from animal models and human risk factors, reduced placental perfusion and/or certain disease states (metabolic, immune and cardiovascular) lie upstream. Recent evidence suggests the surprising conclusion that isolation and culture of cytotrophoblasts from the placentas of pregnancies complicated by preeclampsia enables normalization of their gene expression. The affected molecules include SEMA3B, which down-regulates vascular endothelial growth factor signaling through the PI3K/AKT and GSK3 pathways. Thus, some aspects of the aberrant differentiation of cytotrophoblasts within the uterine wall that is observed in situ may be reversible. The next challenge is asking what the instigating causes are. There is added urgency to finding the answers, because these pathways could be valuable therapeutic targets for reversing abnormal placental function in patients.

Comprehensive analysis of preeclampsia-associated DNA methylation in the placenta

BACKGROUND

A small number of recent reports have suggested that altered placental DNA methylation may be associated with early onset preeclampsia. It is important that further studies be undertaken to confirm and develop these findings. We therefore undertook a systematic analysis of DNA methylation patterns in placental tissue from 24 women with preeclampsia and 24 with uncomplicated pregnancy outcome.

METHODS

We analyzed the DNA methylation status of approximately 27,000 CpG sites in placental tissues in a massively parallel fashion using an oligonucleotide microarray. Follow up analysis of DNA methylation at specific CpG loci was performed using the Epityper MassArray approach and high-throughput bisulfite sequencing.

RESULTS

Preeclampsia-specific DNA methylation changes were identified in placental tissue samples irrespective of gestational age of delivery. In addition, we identified a group of CpG sites within specific gene sequences that were only altered in early onset-preeclampsia (EOPET) although these DNA methylation changes did not correlate with altered mRNA transcription. We found evidence that fetal gender influences DNA methylation at autosomal loci but could find no clear association between DNA methylation and gestational age.

CONCLUSION

Preeclampsia is associated with altered placental DNA methylation. Fetal gender should be carefully considered during the design of future studies in which placental DNA is analyzed at the level of DNA methylation. Further large-scale analyses of preeclampsia-associated DNA methylation are necessary.

RNA interference-mediated knockdown of Notch-1 inhibits migration and invasion, down-regulates matrix metalloproteinases and suppresses NF-κB signaling pathway in trophoblast cells

Preeclampsia is well known to present with reduced trophoblast invasion into the placental bed. Notch-1, a ligand-activated transmembrane receptor, has been reported to be down-regulated in preeclamptic human placentas. This study was conducted to explore the role of Notch-1 in the cell migration and invasion of a human trophoblast cell line, JEG3 cells. Short hairpin RNA (shRNA)-mediated RNA interference was performed to effectively suppress the endogenous expression of Notch-1 at both mRNA and protein levels in JEG3 cells. Results of wound healing and transwell assays showed that knockdown of Notch-1 reduced trophoblast cell migration and invasion. The protein expressions and activities of matrix metalloproteinase (MMP)-2 and MMP-9 were reduced in JEG3 cell when Notch-1 was decreased. Furthermore, the epithelial-cadherin (E-cadherin) expression increased in JEG3 cells when Notch-1 was inhibited, whereas its suppressor Snail decreased in these cells. Moreover, knockdown of Notch-1 also suppressed NF-κB signaling pathway by inhibiting the phosphorylation of nuclear factor kappa B (NF-κB p65) inhibitor (IκBα) and the subsequent nuclear translocation of NF-κB subunit p65 in JEG3 cells. In summary, we demonstrate that Notch-1 contributes to trophoblast cell migration and invasion and that it may be involved in the pathology of human preeclampsia.

Analysis of the placental tissue transcriptome of normal and preeclampsia complicated pregnancies

Preeclampsia is one of the most severe gestational complications which is one of the leading causes of maternal and perinatal morbidity and mortality. A growth in the incidence of severe and combined forms of the pathology has been observed in recent years. According to modern concepts, inadequate cytotrophoblast invasion into the spiral arteries of the uterus and development of the ischemia-reperfusion syndrome in the placental tissue play the leading role in the development of preeclampsia, which is characterized by multipleorgan failure. In this regard, our work was aimed at studying the patterns of placental tissue transcriptome that are specific to females with PE and with physiological pregnancy, as well as identifying the potential promising biomarkers and molecular mechanisms of this pathology. We have identified 63 genes whose expression proved to differ significantly in the placental tissue of females with PE and with physiological pregnancy. A cluster of differentially expressed genes (DEG) whose expression level is increased in patients with preeclampsia includes not only the known candidate genes that have been identified in many other genome-wide studies (e.g., LEP, BHLHB2, SIGLEC6, RDH13, BCL6), but also new genes (ANKRD37, SYDE1, CYBA, ITGB2, etc.), which can be considered as new biological markers of preeclampsia and are of further interest. The results of a functional annotation of DEG show that the development of preeclampsia may be related to a stress response, immune processes, the regulation of cell-cell interactions, intracellular signaling cascades, etc. In addition, the features of the differential gene expression depending on preeclampsia severity were revealed. We have found evidence of the important role of the molecular mechanisms responsible for the failure of immunological tolerance and initiation of the pro-inflammatory cascade in the development of severe preeclampsia. The results obtained elaborate the concept of the pathophysiology of preeclampsia and contain the information necessary to work out measures for targeted therapy of this disease. ;

Matrix metalloproteinase-9 deficiency phenocopies features of preeclampsia and intrauterine growth restriction

The pregnancy complication preeclampsia (PE), which occurs in approximately 3% to 8% of human pregnancies, is characterized by placental pathologies that can lead to significant fetal and maternal morbidity and mortality. Currently, the only known cure is delivery of the placenta. As the etiology of PE remains unknown, it is vital to find models to study this common syndrome. Here we show that matrix metalloproteinase-9 (MMP9) deficiency causes physiological and placental abnormalities in mice, which mimic features of PE. As with the severe cases of this syndrome, which commence early in gestation, MMP9-null mouse embryos exhibit deficiencies in trophoblast differentiation and invasion shortly after implantation, along with intrauterine growth restriction or embryonic death. Reciprocal embryo transfer experiments demonstrated that embryonic MMP9 is a major contributor to normal implantation, but maternal MMP9 also plays a role in embryonic trophoblast development. Pregnant MMP9-null mice bearing null embryos exhibited clinical features of PE as VEGF dysregulation and proteinuria accompanied by preexisting elevated blood pressure and kidney pathology. Thus, our data show that fetal and maternal MMP9 play a role in the development of PE and establish the MMP9-null mice as a much-needed model to study the clinical course of this syndrome.

miR-16 inhibits the proliferation and angiogenesis-regulating potential of mesenchymal stem cells in severe pre-eclampsia

Pre-eclampsia is thought to be a systemic disease of maternal endothelial cell dysfunctions. miRNAs regulate various basic biological functions in cells, including stem cells. Mesenchymal stem cells exist in almost all tissues and are the key cellular source for tissue repair and regeneration. Our aims are to investigate whether miRNAs regulate MSCs in fetal-maternal interfaces to influence the pathogenesis of pre-eclampsia. The differential expression of miRNAs in decidua-derived mesenchymal stem cells of all patients with severe pre-eclampsia (n = 20) and normal groups (n = 20) was first screened by microarray analysis and validated by quantitative real-time PCR analysis. The integrated bioinformatics analysis showed that miR-16 showed the highest number of connections in the miRNA GO network and the miRNA gene network. Moreover, over-expressed miR-16 inhibited the proliferation and migration of decidua-derived mesenchymal stem cells and induced cell-cycle arrest by targeting cyclin E1. Interestingly, over-expression of miR-16 by decidua-derived mesenchymal stem cells reduced the ability of human umbilical vein endothelial cells to form blood vessels and reduced the migration of trophoblast cells. Furthermore, decidua-derived mesenchymal stem cell-expressed endothelial growth factor VEGF-A was involved in migration of trophoblast cells and human umbilical vein endothelial cells as well as tube and network formation. Importantly, the levels of cyclin E1 and VEGF-A were negatively correlated with the level of miR-16 expression in decidua-derived mesenchymal stem cells from the patients with severe pre-eclampsia. Together, these data suggest that the alteration of miR-16 expression in decidua-derived mesenchymal stem cells may be involved in the development of pre-eclampsia.

Endothelial FOS expression and pre-eclampsia

OBJECTIVE

To study gene expression profiles in human endothelial cells incubated with plasma from women who developed pre-eclampsia and women with normotensive pregnancies.

DESIGN

A case-control study.

SETTING

A longitudinal nested case-control study within three maternity units.

POPULATION

A mixed obstetric population attending maternity hospitals in Glasgow.

METHODS

Plasma was obtained at both 16 and 28 weeks of gestation from 12 women: six women subsequently developed pre-eclampsia (cases) and six women, matched for age, body mass index (BMI) and parity, remained normotensive (controls). Human umbilical vein endothelial cells (HUVECs) were incubated with plasma for 24 hour before RNA isolation.

MAIN OUTCOME MEASURES

Gene expression profiles were compared between the two gestational time points using Illumina(®) HumanHT-12 v4 Expression BeadChips. Differential mRNA expression observed in microarray experiments were validated using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), and gene networks were analysed using Ingenuity(®) pathway analysis.

RESULTS

There was a significant difference in the expression of 25 genes following incubation with plasma from controls, and an increase in the expression of 11 genes following incubation with plasma from cases, with no overlap between the two groups (false discovery rate, FDR < 0.05). There was a 3.74-fold (FDR < 0.001) increase in the expression of the c-Fos gene (FOS) when HUVECs were incubated with control plasma from 16 and 28 weeks of gestation, with no significant difference between the two time points with plasma from cases. Similar findings for FOS were obtained by qRT-PCR.

CONCLUSIONS

Plasma from women who subsequently develop pre-eclampsia appears to contain factors that lead to the dysregulation of FOS in endothelial cells during pregnancy. Reduced expression of c-Fos may lead to impaired vasculogenesis, and thereby contribute to the development of pre-eclampsia.

Preeclampsia: a bioinformatics approach through protein-protein interaction networks analysis

Background

In this study we explored preeclampsia through a bioinformatics approach. We create a comprehensive genes/proteins dataset by the analysis of both public proteomic data and text mining of public scientific literature. From this dataset the associated protein-protein interaction network has been obtained. Several indexes of centrality have been explored for hubs detection as well as the enrichment statistical analysis of metabolic pathway and disease.

Results

We confirmed the well known relationship between preeclampsia and cardiovascular diseases but also identified statistically significant relationships with respect to cancer and aging. Moreover, significant metabolic pathways such as apoptosis, cancer and cytokine-cytokine receptor interaction have also been identified by enrichment analysis. We obtained FLT1, VEGFA, FN1, F2 and PGF genes with the highest scores by hubs analysis; however, we also found other genes as PDIA3, LYN, SH2B2 and NDRG1 with high scores.

Conclusions

The applied methodology not only led to the identification of well known genes related to preeclampsia but also to propose new candidates poorly explored or completely unknown in the pathogenesis of preeclampsia, which eventually need to be validated experimentally. Moreover, new possible connections were detected between preeclampsia and other diseases that could open new areas of research. More must be done in this area to resolve the identification of unknown interactions of proteins/genes and also for a better integration of metabolic pathways and diseases.

Early detection of maternal risk for preeclampsia

Preeclampsia is one of the leading causes of maternal and fetal morbidity and mortality. New molecular insights offer new possibilities of early diagnosis of elevated maternal risk. Maternal risk factors, biophysical parameters like Doppler examination of the uterine arteries and biochemical parameters allow early risk calculation. Preventive and effective therapeutic agents like acetylsalicylacid can be started in the early second trimester. This article reviews the diagnostic possibilities of early risk calculation to detect women having high risk for preeclampsia and the potential benefits for them, the offspring and health care systems. We provide risk calculation for preeclampsia as an important and sensible part of first trimester screening.