MicroRNA expression profiles of trophoblastic cells

MicroRNA expression profile in the basal plate of human placenta associates with spontaneous preterm birth

INTRODUCTION

MicroRNAs regulate post-transcriptional gene expression. Their expression has been linked to many pregnancy complications, including preterm birth. Placental microRNA levels differ between preterm and term pregnancies. Not much is known about the targets that are affected by these differences in microRNA expression. We investigated associations between microRNA expression levels in the basal plate of the placenta and their targets and the onset of preterm birth.

METHODS

MiRNAomes of spontaneous preterm (n = 6) and term (n = 6) placentas were characterized using RNA sequencing. MicroRNA target and enrichment analyses were performed to explore potential gene targets and pathways. Selected findings were validated using qPCR (n = 41). MicroRNA mimic transfection and luciferase reporter assays were performed to test if certain microRNAs regulate their predicted target, SLIT2, the expression of which has been shown to associate with preterm birth.

RESULTS

We identified 39 differentially expressed microRNAs from the preterm placentas compared to term. Many downregulated microRNAs were from the placenta-specific C14MC microRNA cluster. Target gene and pathway analyses showed that microRNAs that associate with preterm birth target transcription related factors and genes linked with protein binding and invasive pathways. Eight of the identified microRNAs putatively target SLIT2, including miR-766-3p and miR-489-3p. Luciferase reporter assay suggested that these microRNAs regulate SLIT2 expression.

DISCUSSION

MicroRNA expression changes are associated with spontaneous preterm birth. A group of microRNAs targeting the same gene or genes belonging to the same pathway can have a significant effect on the critical processes maintaining pregnancy and placental functions.

Trophoblast microRNAs, pre-eclampsia and intrauterine growth restriction

MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that play a role in regulating gene expression in a tissue-specific manner. Placental miRNAs expression pattern dynamically changes during pregnancy influencing cell proliferation, differentiation and apoptosis. Changes of specific miRNA levels have been described in pregnancies complicated by hypertensive disorders or gestational diabetes and a growing interest in understanding miRNA role on placental development and placental disorders is currently going on. The present review evaluates the possible roles of miRNAs in trophoblastic invasion and placental development as well as their potential role as biomarkers for the prediction of placental disorders focusing the attention on intrauterine growth restriction.

Comparison of Four Protocols for In Vitro Differentiation of Human Embryonic Stem Cells into Trophoblast Lineages by BMP4 and Dual Inhibition of Activin/Nodal and FGF2 Signaling

Human embryonic stem cells (hESCs) cultured in media containing bone morphogenic protein 4 (BMP4; B) differentiate into trophoblast-like cells. Supplementing media with inhibitors of activin/nodal signaling (A83-01) and of fibroblast growth factor 2 (PD173074) suppresses mesoderm and endoderm formation and improves specification of trophoblast-like lineages, but with variable effectiveness. We compared differentiation in four BMP4-containing media: mTeSR1-BMP4 only, mTeSR1-BAP, basal medium with BAP (basal-BAP), and a newly defined medium, E7-BAP. These media variably drive early differentiation towards trophoblast-like lineages with upregulation of early trophoblast markers CDX2 and KRT7 and downregulation of pluripotency markers (OCT4 and NANOG). As expected, based on differences between media in FGF2 and its inhibitors, downregulation of mesendoderm marker EOMES was variable between media. By day 7, only hESCs grown in E7-BAP or basal-BAP expressed HLA-G protein, indicating the presence of cells with extravillous trophoblast characteristics. Expression of HLA-G and other differentiation markers (hCG, KRT7, and GCM1) was highest in basal-BAP, suggesting a faster differentiation in this medium, but those cultures were more inhomogeneous and still expressed some endodermal and pluripotency markers. In E7-BAP, HLA-G expression increased later and was lower. There was also a low but maintained expression of some C19MC miRNAs, with more CpG hypomethylation of the ELF5 promoter, suggesting that E7-BAP cultures differentiate slower along the trophoblast lineage. We conclude that while all protocols drive differentiation into trophoblast lineages with varying efficiency, they have advantages and disadvantages that must be considered when selecting a protocol for specific experiments.

MiR-135b-5p targets ADAM12 to suppress invasion and accelerate trophoblast apoptosis in preeclampsia

INTRODUCTION

Preeclampsia was a serious complication often leaded to adverse pregnancy outcomes. Abnormal placental miR-135b-5p expression in preeclampsia was observed in our preliminary investigation. However, the role of miR-135b-5p in preeclampsia was unclear.

METHODS

We determined the miR-135b-5p expression pattern at the fetomaternal interface and levels in placental tissue and exosomes. MiR-135b-5p expression in the trophoblast cell line HTR8/SVneo was manipulated by transient agomir or antagomir transfection or establishment of HTR8/SVneo cell line stably overexpressing miR-135b or miR-135b-5p-sponger. Then the function of miR-135b-5p on the motility of HTR8/SVneo cells, and its effects on cell viability was determined. Finally, we confirmed the relationship between miR-135b-5p and ADAM12.

RESULTS

MiR-135b-5p exclusively expressed in the villous cytotrophoblast, and extravillous trophoblast. Significant miR-135b-5p upregulation was observed in the placenta and peripheral plasma exosomes in preeclampsia, and could be a highly sensitive molecular marker for preeclampsia. Elevated miR-135b-5p expression significantly promoted apoptosis and inhibited HTR8/SVneo cell invasion and migration. Binding of miR-135b-5p to the ADAM12 mRNA 3'-untranslated region was predicted by bioinformatics analysis and confirmed using a dual-luciferase reporter assay. High miR-135-5p levels inhibit the invasion and migration of trophoblastic cells, possibly by directly binding to the 3'-UTR of DADM12 and suppressing its translation efficiency, thereby nullifying the promotion of trophoblast invasion and migration via ADAM12.

DISCUSSION

Abnormal upregulation of miR-135b-5p may be involved in preeclampsia through triggering trophoblast apoptosis and impeding trophoblast invasion and migration by targeting ADAM12.

Analysis of a mouse germ cell tumor model establishes pluripotency-associated miRNAs as conserved serum biomarkers for germ cell cancer detection

Malignant testicular germ cells tumors (TGCTs) are the most common solid cancers in young men. Current TGCT diagnostics include conventional serum protein markers, but these lack the sensitivity and specificity to serve as accurate markers across all TGCT subtypes. MicroRNAs (miRNAs) are small non-coding regulatory RNAs and informative biomarkers for several diseases. In humans, miRNAs of the miR-371-373 cluster are detectable in the serum of patients with malignant TGCTs and outperform existing serum protein markers for both initial diagnosis and subsequent disease monitoring. We previously developed a genetically engineered mouse model featuring malignant mixed TGCTs consisting of pluripotent embryonal carcinoma (EC) and differentiated teratoma that, like the corresponding human malignancies, originate in utero and are highly chemosensitive. Here, we report that miRNAs in the mouse miR-290-295 cluster, homologs of the human miR-371-373 cluster, were detectable in serum from mice with malignant TGCTs but not from tumor-free control mice or mice with benign teratomas. miR-291-293 were expressed and secreted specifically by pluripotent EC cells, and expression was lost following differentiation induced by the drug thioridazine. Notably, miR-291-293 levels were significantly higher in the serum of pregnant dams carrying tumor-bearing fetuses compared to that of control dams. These findings reveal that expression of the miR-290-295 and miR-371-373 clusters in mice and humans, respectively, is a conserved feature of malignant TGCTs, further validating the mouse model as representative of the human disease. These data also highlight the potential of serum miR-371-373 assays to improve patient outcomes through early TGCT detection, possibly even prenatally.

The role of miRNA molecules in the miscarriage process

The etiology and pathogenesis of miscarriage, which is the most common pregnancy complication, have not been fully elucidated. There is a constant search for new screening biomarkers that would allow for the early diagnosis of disorders associated with pregnancy pathology. The profiling of microRNA expression is a promising research area, which can help establish the predictive factors for pregnancy diseases. Molecules of microRNAs are involved in several processes crucial for the development and functioning of the body. These processes include cell division and differentiation, programmed cell death, blood vessel formation or tumorigenesis, and the response to oxidative stress. The microRNAs affect the number of individual proteins in the body due to their ability to regulate gene expression at the post-transcriptional level, ensuring the normal course of many cellular processes. Based on the scientific facts available, this paper presents a compendium on the role of microRNA molecules in the miscarriage process. The expression of potential microRNA molecules as early minimally invasive diagnostic biomarkers may be evaluated as early as the first weeks of pregnancy and may constitute a monitoring factor in the individual clinical care of women in early pregnancy, especially after the first miscarriage. To summarize, the described scientific data set a new direction of research in the development of preventive care and prognostic monitoring of the course of pregnancy.

Establishment of the fetal-maternal interface: developmental events in human implantation and placentation

Early pregnancy is a complex and well-orchestrated differentiation process that involves all the cellular elements of the fetal-maternal interface. Aberrant trophoblast-decidual interactions can lead to miscarriage and disorders that occur later in pregnancy, including preeclampsia, intrauterine fetal growth restriction, and preterm labor. A great deal of research on the regulation of implantation and placentation has been performed in a wide range of species. However, there is significant species variation regarding trophoblast differentiation as well as decidual-specific gene expression and regulation. Most of the relevant information has been obtained from studies using mouse models. A comprehensive understanding of the physiology and pathology of human implantation and placentation has only recently been obtained because of emerging advanced technologies. With the derivation of human trophoblast stem cells, 3D-organoid cultures, and single-cell analyses of differentiated cells, cell type-specific transcript profiles and functions were generated, and each exhibited a unique signature. Additionally, through integrative transcriptomic information, researchers can uncover the cellular dysfunction of embryonic and placental cells in peri-implantation embryos and the early pathological placenta. In fact, the clinical utility of fetal-maternal cellular trafficking has been applied for the noninvasive prenatal diagnosis of aneuploidies and the prediction of pregnancy complications. Furthermore, recent studies have proposed a viable path toward the development of therapeutic strategies targeting placenta-enriched molecules for placental dysfunction and diseases.

Prediction of Early- and Late-Onset Pre-Eclampsia in the Preclinical Stage via Placenta-Specific Extracellular miRNA Profiling

Pre-eclampsia (PE) is one of the severe complications of pregnancy in 3-8% of all cases and is one of the leading causes of maternal and perinatal mortality. The fundamental role in the pathogenesis of PE is assigned to maternal and/or placental factors, whereby the combination and manifestation of which determines the time of onset of the clinical symptoms of PE (before or after 34 weeks of gestation) and their severity. It is known that the expression level of miRNAs, the regulators of signaling cascades in the cell, depends on gestational age. In the present study, we focused on the identification of the placenta-specific miRNAs that differentiate between early- and late-onset pre-eclampsia (ePE and lPE) throughout pregnancy, from the first to the third trimester. A total of 67 patients were analyzed using small RNA deep sequencing and real-time quantitative PCR, which resulted in a core list of miRNAs (let-7b-5p, let-7d-3p, let-7f-5p, let-7i-5p, miR-22-5p, miR-451a, miR-1246, miR-30e-5p, miR-20a-5p, miR-1307-3p, and miR-320e), which in certain combinations can predict ePE or lPE with 100% sensitivity and 84-100% specificity in the 1st trimester of pregnancy. According to the literature data, these miRNA predictors of PE control trophoblast proliferation, invasion, migration, syncytialization, the endoplasmic reticulum unfolded protein response, immune tolerance, angiogenesis, and vascular integrity. The simultaneous detection of let-7d-3p, miR-451a, and miR-1307-3p, resistant to the repeated freezing/thawing of blood serum samples, in combination with biochemical (b-hCG and PAPP-A) and ultrasound (UAPI) parameters, allowed us to develop a universal model for the prediction of ePE and lPE onset (FPR = 15.7% and FNR = 9.5%), which was validated using a test cohort of 48 patients and demonstrated false-positive results in 26.7% of cases and false negatives in 5.6% of cases. For comparison, the use of the generally accepted Astraia program in the analysis of the test cohort of patients led to worse results: FPR = 62.1% and FNR = 33.3%.

A burst of genomic innovation at the origin of placental mammals mediated embryo implantation

The origin of embryo implantation in mammals ~148 million years ago was a dramatic shift in reproductive strategy, yet the molecular changes that established mammal implantation are largely unknown. Although progesterone receptor signalling predates the origin of mammals and is highly conserved in, and critical for, successful mammal pregnancy, it alone cannot explain the origin and subsequent diversity of implantation strategies throughout the placental mammal radiation. MiRNAs are known to be flexible and dynamic regulators with a well-established role in the pathophysiology of mammal placenta. We propose that a dynamic core microRNA (miRNA) network originated early in placental mammal evolution, responds to conserved mammal pregnancy cues (e.g. progesterone), and facilitates species-specific responses. Here we identify 13 miRNA gene families that arose at the origin of placental mammals and were subsequently retained in all descendent lineages. The expression of these miRNAs in response to early pregnancy molecules is regulated in a species-specific manner in endometrial epithelia of species with extreme implantation strategies (i.e. bovine and human). Furthermore, this set of miRNAs preferentially target proteins under positive selective pressure on the ancestral eutherian lineage. Discovery of this core embryo implantation toolkit and specifically adapted proteins helps explain the origin and evolution of implantation in mammals.

Epigenetic Mechanisms Involved in the Effects of Maternal Hyperhomocysteinemia on the Functional State of Placenta and Nervous System Plasticity in the Offspring

According to modern view, susceptibility to diseases, specifically to cognitive and neuropsychiatric disorders, can form during embryonic development. Adverse factors affecting mother during the pregnancy increase the risk of developing pathologies. Despite the association between elevated maternal blood homocysteine (Hcy) and fetal brain impairments, as well as cognitive deficits in the offspring, the role of brain plasticity in the development of these pathologies remains poorly studied. Here, we review the data on the negative impact of hyperhomocysteinemia (HHcy) on the neural plasticity, in particular, its possible influence on the offspring brain plasticity through epigenetic mechanisms, such as changes in intracellular methylation potential, activity of DNA methyltransferases, DNA methylation, histone modifications, and microRNA expression in brain cells. Since placenta plays a key role in the transport of nutrients and transmission of signals from mother to fetus, its dysfunction due to aberrant epigenetic regulation can affect the development of fetal CNS. The review also presents the data on the impact of maternal HHcy on the epigenetic regulation in the placenta. The data presented in the review are not only interesting from purely scientific point of view, but can help in understanding the role of HHcy and epigenetic mechanisms in the pathogenesis of diseases, such as pregnancy pathologies resulting in the delayed development of fetal brain, cognitive impairments in the offspring during childhood, and neuropsychiatric and neurodegenerative disorders later in life, as well as in the search for approaches for their prevention using neuroprotectors.

The Role of Placental Non-Coding RNAs in Adverse Pregnancy Outcomes

Non-coding RNAs (ncRNAs) are transcribed from the genome and do not encode proteins. In recent years, ncRNAs have attracted increasing attention as critical participants in gene regulation and disease pathogenesis. Different categories of ncRNAs, which mainly include microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are involved in the progression of pregnancy, while abnormal expression of placental ncRNAs impacts the onset and development of adverse pregnancy outcomes (APOs). Therefore, we reviewed the current status of research on placental ncRNAs and APOs to further understand the regulatory mechanisms of placental ncRNAs, which provides a new perspective for treating and preventing related diseases.

Identification of altered miRNAs and their targets in placenta accreta

Placenta accreta spectrum (PAS) is one of the major causes of maternal morbidity and mortality worldwide with increasing incidence. PAS refers to a group of pathological conditions ranging from the abnormal attachment of the placenta to the uterus wall to its perforation and, in extreme cases, invasion into surrounding organs. Among them, placenta accreta is characterized by a direct adhesion of the villi to the myometrium without invasion and remains the most common diagnosis of PAS. Here, we identify the potential regulatory miRNA and target networks contributing to placenta accreta development. Using small RNA-Seq followed by RT-PCR confirmation, altered miRNA expression, including that of members of placenta-specific miRNA clusters (e.g., C19MC and C14MC), was identified in placenta accreta samples compared to normal placental tissues. In situ hybridization (ISH) revealed expression of altered miRNAs mostly in trophoblast but also in endothelial cells and this profile was similar among all evaluated degrees of PAS. Kyoto encyclopedia of genes and genomes (KEGG) analyses showed enriched pathways dysregulated in PAS associated with cell cycle regulation, inflammation, and invasion. mRNAs of genes associated with cell cycle and inflammation were downregulated in PAS. At the protein level, NF-κB was upregulated while PTEN was downregulated in placenta accreta tissue. The identified miRNAs and their targets are associated with signaling pathways relevant to controlling trophoblast function. Therefore, this study provides miRNA:mRNA associations that could be useful for understanding PAS onset and progression.

MicroRNAs: key regulators of the trophoblast function in pregnancy disorders

The placenta is essential for a successful pregnancy and healthy intrauterine development in mammals. During human pregnancy, the growth and development of the placenta are inseparable from the rapid proliferation, invasion, and migration of trophoblast cells. Previous reports have shown that the occurrence of many pregnancy disorders may be closely related to the dysfunction of trophoblasts. However, the function regulation of human trophoblast cells in the placenta is poorly understood. Therefore, studying the factors that regulate the function of trophoblast cells is necessary. MicroRNAs (miRNAs) are small, non-coding, single-stranded RNA molecules. Increasing evidence suggests that miRNAs play a crucial role in regulating trophoblast functions. This review outlines the role of miRNAs in regulating the function of trophoblast cells and several common signaling pathways related to miRNA regulation in pregnancy disorders.

Alterations in maternal plasma exosomal miRNAs revealed selective material exchange between maternal circulation and placenta

AIM

Exosomes have emerged as important regulators in the communication between maternal peripheral blood and placenta. We aimed to compare maternal plasma exosomal miRNAs profile between healthy pregnant and nonpregnant women, screen for differential expressed miRNAs and their potential regulatory role during pregnancy.

METHODS

We isolated exosomes from plasma of mid-trimester, last trimester, and nonpregnant women (n = 6 each group), analyzed the miRNA profile using next-generation sequencing.

RESULTS

Several miRNA clusters were expressed in plasma exosomes, such as C19MC, C14MC, and let-7 family, miRNAs in each cluster may have synergistic effect during pregnancy. We assumed maternal circulating exosomal miRNA could be transported into placenta or selectively uptook by placenta, which was consistent with the fact that many pregnancy-associated or placenta highly expressed miRNAs reduced in exosomes during pregnancy. Some exosomal miRNAs were mainly secreted by the placenta, which could act as markers that reflect changes in the function and microenvironment of the placenta.

CONCLUSIONS

Exosomal miRNAs are associated with placenta development and have potential as molecular markers.

Role of microRNAs regulating trophoblast cell function in the pathogenesis of pre‑eclampsia (Review)

Pre-eclampsia (PE) is a complicated pregnancy-specific disease and is considered the primary reason for maternal and foetal mortality and morbidity. PE has a multifactorial pathogenesis but the causes of PE remain unclear. The functions of trophoblasts, including differentiation, proliferation, migration, invasion and apoptosis, are essential for successful pregnancy. During the early stages of placental development, trophoblasts are strictly regulated by several molecular pathways; however, an imbalance of these molecular pathways can lead to severe placental lesions and pregnancy complications. Certain microRNAs (miRs) are abnormally expressed in PE, with several miRs involved in the regulation of pregnancy-associated genes. The present review discusses the miRs regulating trophoblast function, how they affect the pathogenesis of PE and evaluating the possibility of miRs in screening, diagnosis and treatment of PE.

Dynamic regulation of the transcriptome and proteome of the equine embryo during maternal recognition of pregnancy

During initial maternal recognition of pregnancy (MRP), the equine embryo displays a series of unique events characterized by rapid blastocyst expansion, secretion of a diverse array of molecules, and transuterine migration to interact with the uterine surface. Up to date, the intricate transcriptome and proteome changes of the embryo underlying these events have not been critically studied in horses. Thus, the objective of this study was to perform an integrative transcriptomic (including mRNA, miRNAs, and other small non-coding RNAs) and proteomic analysis of embryos collected from days 10 to 13 of gestation. The results revealed dynamic transcriptome profiles with a total of 1311 differentially expressed genes, including 18 microRNAs (miRNAs). Two main profiles for mRNAs and miRNAs were identified, one with higher expression in embryos ≤5 mm and the second with higher expression in embryos ≥7 mm. At the protein level, similar results were obtained, with 259 differentially abundant proteins between small and large embryos. Overall, the findings demonstrated fine-tuned transcriptomic and proteomic regulations in the developing embryo associated with embryo growth. The identification of specific regulation of mRNAs, proteins, and miRNAs on days 12 and 13 of gestation suggested these molecules as pivotal for embryo development and as involved in MRP, and in establishment of pregnancy in general. In addition, the results revealed new insights into prostaglandin synthesis by the equine embryo, miRNAs and genes potentially involved in modulation of the maternal immune response, regulation of endometrial receptivity and of late implantation in the mare.

The Role of Cluster C19MC in Pre-Eclampsia Development

Pre-eclampsia is a placenta-related complication occurring in 2-10% of all pregnancies. miRNAs are a group of non-coding RNAs regulating gene expression. There is evidence that C19MC miRNAs are involved in the development of the placenta. Deregulation of chromosome 19 microRNA cluster (C19MC) miRNAs expression leads to impaired cell differentiation, abnormal trophoblast invasion and pathological angiogenesis, which can lead to the development of pre-eclampsia. Information was obtained through a review of articles available in PubMed Medline. Articles on the role of the C19MC miRNA in the development of pre-eclampsia published in 2009-2022 were analyzed. This review article summarizes the current data on the role of the C19MC miRNA in the development of pre-eclampsia. They indicate a significant increase in the expression of most C19MC miRNAs in placental tissue and a high level of circulating fractions in serum and plasma, both in the first and/or third trimester in women with PE. Only for miR-525-5p, low levels of plasma expression were noted in the first trimester, and in the placenta in the third trimester. The search for molecular factors indicating the development of pre-eclampsia before the onset of clinical symptoms seems to be a promising diagnostic route. Identifying women at risk of developing pre-eclampsia at the pre-symptomatic stage would avoid serious complications in both mothers and fetuses. We believe that miRNAs belonging to cluster C19MC could be promising biomarkers of pre-eclampsia development.

Global microRNA and protein expression in human term placenta

Introduction

Description of the global expression of microRNAs (miRNAs) and proteins in healthy human term placentas may increase our knowledge of molecular biological pathways that are important for normal fetal growth and development in term pregnancy. The aim of this study was to explore the global expression of miRNAs and proteins, and to point out functions of importance in healthy term placentas.

Materials and methods

Placental samples (n = 19) were identified in a local biobank. All samples were from uncomplicated term pregnancies with vaginal births and healthy, normal weight newborns. Next-generation sequencing and nano-scale liquid chromatographic tandem mass spectrometry were used to analyse miRNA and protein expression, respectively.

Results

A total of 895 mature miRNAs and 6,523 proteins were detected in the placentas, of which 123 miRNAs and 346 proteins were highly abundant. The miRNAs were in high degree mapped to chromosomes 19, 14, and X. Analysis of the highly abundant miRNAs and proteins showed several significantly predicted functions in common, including immune and inflammatory response, lipid metabolism and development of the nervous system.

Discussion

The predicted function inflammatory response may reflect normal vaginal delivery, while lipid metabolism and neurodevelopment may be important processes for the term fetus. The data presented in this study, with complete miRNA and protein findings, will enhance the knowledge base for future research in the field of placental function and pathology.

Decorin–induced, preeclampsia-associated microRNA-512-3p restrains extravillous trophoblast functions by targeting USF2/PPP3R1 axis

Decorin (DCN) is a leucine-rich proteoglycan produced by chorionic villus mesenchymal cells anddecidual cells during human pregnancy. Studies from our laboratory demonstrated that decidua-derived DCN restrains multiple trophoblast functions including proliferation, migration, invasion andendovascular differentiation, mediated by DCN-binding to multiple tyrosine kinase receptors; expressed by the trophoblast. Furthermore, DCN was shown to be selectively over-produced by thedecidua in preeclampsia (PE) subjects and elevated in the second trimester maternal plasma in PE, before the appearance of clinical signs, presenting as a predictive biomarker for PE. Micro (mi)RNAs are single-stranded non-coding RNAs (17–25 nucleotides) that typically downregulate target genes by repressing translation or facilitating degradation of mRNAs. The human; placenta expresses many miRNAs, some of which are exclusively expressed by the trophoblast. Many; of these miRNAs are dysregulated in PE-associated placentas and some appear in the maternal blood as PE biomarkers. However, little is known about their contribution to the pathogenesis of PE, a multi-factorial disease associated with a hypo-invasive placenta. The objective of the present study was to examine whether exposure of extravillous trophoblast (EVT) to DCN affects expression of specific miRNAs, and to test the role of these miRNAs in altering EVT functions. We identified miR-512-3p, as one of the DCN-induced miRNAs, also upregulated in PE placentas. It was shown to be elevated in ectopic DCN-over-expressing or exogenous DCN-treated first trimester human trophoblast cell line HTR-8/SVneo. Use of miRNA-mimics and inhibitors revealed that miR-512-3p compromised trophoblast migration, invasion and VEGF-dependent endovascular differentiation. Finally, Protein Phosphatase 3 Regulatory Subunit B, Alpha (PPP3R1), a known target of miR-512-3p, was paradoxically elevated in miR-512-3p-overexpressing trophoblast and PE-associated placentas. Using Enrichr, a tool that consists of both a validated user-submitted gene list and a search engine for transcription factors, we found that PPP3R1 elevation resulted from the miRNA binding to and targeting Upstream Transcription Factor 2 (USF2) which targeted PPP3R1. These findings reveal a novel aspect of pathogenesis of PE and biomarker potentials of this miRNA in PE.

Role of microRNAs in trophoblast invasion and spiral artery remodeling: Implications for preeclampsia

It is now well-established that microRNAs (miRNAs) are important regulators of gene expression. The role of miRNAs in placental development and trophoblast function is constantly expanding. Trophoblast invasion and their ability to remodel uterine spiral arteries are essential for proper placental development and successful pregnancy outcome. Many miRNAs are reported to be dysregulated in pregnancy complications, especially preeclampsia and they exert various regulatory effects on trophoblasts. In this review, we provide a brief overview of miRNA biogenesis and their mechanism of action, as well as of trophoblasts differentiation, invasion and spiral artery remodeling. We then discuss the role of miRNAs in trophoblasts invasion and spiral artery remodeling, focusing on miRNAs that have been thoroughly investigated, especially using multiple model systems. We also discuss the potential role of miRNAs in the pathogenesis of preeclampsia.

Micro-RNAs in Human Placenta: Tiny Molecules, Immense Power

Micro-RNAs (miRNAs) are short non-coding single-stranded RNAs that modulate the expression of various target genes after transcription. The expression and distribution of kinds of miRNAs have been characterized in human placenta during different gestational stages. The identified miRNAs are recognized as key mediators in the regulation of placental development and in the maintenance of human pregnancy. Aberrant expression of miRNAs is associated with compromised pregnancies in humans, and dysregulation of those miRNAs contributes to the occurrence and development of related diseases during pregnancy, such as pre-eclampsia (PE), fetal growth restriction (FGR), gestational diabetes mellitus (GDM), recurrent miscarriage, preterm birth (PTB) and small-for-gestational-age (SGA). Thus, having a better understanding of the expression and functions of miRNAs in human placenta during pregnancy and thereby developing novel drugs targeting the miRNAs could be a potentially promising method in the prevention and treatment of relevant diseases in future. Here, we summarize the current knowledge of the expression pattern and function regulation of miRNAs in human placental development and related diseases.

Non-Coding RNAs and Prediction of Preeclampsia in the First Trimester of Pregnancy

Preeclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality. The only fundamental treatment for PE is the termination of pregnancy. Therefore, not only severe maternal complications but also perinatal complications due to immaturity of the infant associated with early delivery are serious issues. The treatment and prevention of preterm onset preeclampsia (POPE) are challenging. In 2017, the ASPRE trial showed that a low oral dose of aspirin administered to POPE high-risk women in early pregnancy reduced POPE by 62%. A prediction algorithm at 11–13 weeks of gestation identifies POPE with 75% sensitivity when the false positive rate is set at 10%. New biomarkers to increase the accuracy of the prediction model for POPE high-risk women in early pregnancy are needed. In this review, we focused on non-coding RNAs (ncRNAs) as potential biomarkers for the prediction of POPE. Highly expressed ncRNAs in the placenta in early pregnancy may play crucial roles in placentation. Furthermore, placenta-specific ncRNAs have been detected in maternal blood. In this review, we summarized ncRNAs that were highly expressed in the primary human placenta in early pregnancy. We also presented highly expressed ncRNAs in the placenta that were associated with or predictive of the development of PE in an expression analysis of maternal blood during the first trimester of pregnancy. These previous studies showed that the chromosome 19 microRNA (miRNA) -derived miRNAs (e.g., miR-517-5p, miR-518b, and miR-520h), the hypoxia-inducible miRNA (miR-210), and long non-coding RNA H19, were not only highly expressed in the early placenta but were also significantly up-regulated in the blood at early gestation in pregnant women who later developed PE. These maternal circulating ncRNAs in early pregnancy are expected to be possible biomarkers for POPE.

Circulating extracellular vesicles exhibit a differential miRNA profile in gestational diabetes mellitus pregnancies

We undertook a prospective temporal study collecting blood samples from consenting pregnant women, to test the hypothesis that circulating extracellular vesicles (EVs) carrying specific non-coding microRNA signatures can underlie gestational diabetes mellitus (GDM). To test this hypothesis, miRNA cargo of isolated and characterized EVs revealed contributions from the placenta and differential expression at all three trimesters and at delivery between pregnant and non-pregnant states. Many miRNAs originate from the placental-specific chromosome 19 microRNA cluster (19MC) and chromosome 14 microRNA cluster (14MC). Further a positive correlation emerged between third trimester and at delivery EVs containing miRNAs and those expressed by the corresponding post-parturient placentas (R value = 0.63 to 0.69, p value = 2.2X10-16), in normal and GDM. In addition, distinct differences at all trimesters emerged between women who subsequently developed GDM. Analysis by logistic regression with leave-one-out-cross validation revealed the optimal combination of miRNAs using all the circulating miRNAs (miR-92a-3p, miR-192-5p, miR-451a, miR-122-5p), or using only the differentially expressed miRNAs (has-miR-92a-3p, hsa-miR-92b-3p, hsa-miR-100-5p and hsa-miR-125a-3p) in GDM during the first trimester. As an initial step, both sets of miRNAs demonstrated a predictive probability with an area under the curve of 0.95 to 0.96. These miRNAs targeted genes involved in cell metabolism, proliferation and immune tolerance. In particular genes of the P-I-3-Kinase, FOXO, insulin signaling and glucogenic pathways were targeted, suggestive of placental connectivity with various maternal organs/cells, altering physiology along with pathogenic mechanisms underlying the subsequent development of GDM. We conclude that circulating EVs originating from the placenta with their miRNA cargo communicate and regulate signaling pathways in maternal organs, thereby predetermining development of GDM.

Expression profiles of miR3181 and miR199a in plasma and placenta of virally suppressed HIV-1 infected Cameroonian pregnant women at delivery

Human immunodeficiency virus (HIV)-1 infection during pregnancy reduces the transplacental transfer of protective maternal antibodies needed to confer immunity during early postnatal life. However, the mediation of MicroRNA in this dysregulation is not well understood MicroRNAs 3181 and 199a have been shown to mediate neonatal Fc receptor (FcRn)-like transmembrane antibody transfer and endocytosis respectively but their expression levels in the placenta and plasma in women living with HIV have not been extensively investigated. The objective of this study was to determine how the expression levels of miR-3181 and miR-199a in the placenta and plasma are affected in women chronically infected with HIV who are on antiretroviral therapy (ART) and are virally suppressed at delivery. In this pilot case-control study, plasma and placenta biopsies were obtained from 36 (18 HIV+ and 18 HIV-) Cameroonian women at delivery. MicroRNAs 3181 and 199a expression levels were measured using RT-qPCR, data was analyzed using SPSS22.0 and R 3.60, and p values below 0.05 were considered statistically significant. All the HIV-infected women were on known ART regimens and were virally suppressed. There was no significant difference in the levels of miR-3181 (p>0.05) in the placenta and plasma amongst HIV-infected and HIV uninfected women. The expression levels of miR-199a were significantly greater in the plasma compared to the placenta of HIV+ (p = 0.00005) and HIV- (p = 0.027) women. Moreover, there was a significantly higher (p = 0.02) level of miR-199a in the plasma of women with HIV and their uninfected counterparts. Linear regression models adjusted for systolic pressure showed no significant difference (p>0.05) in the levels of miR-199a and miR-3181 in both the placenta and plasma due to HIV infection. Our findings suggest that even though ART uptake and viral suppression might help in maintaining miR3181 and miR199a levels in the placenta of women with HIV at comparative levels to those of their HIV negative counterparts, the significantly higher levels of miR-199a in the plasma of women with HIV compared to the placenta might highlight lurking systemic dangers and requires further investigation.

Primary Trophoblast Cultures: Characterization of HLA Profiles and Immune Cell Interactions

Introduction

Trophoblasts are essential in fetal-maternal interaction during pregnancy. The goal was to study HLA profiles of primary trophoblasts derived from placentas, and to investigate their usefulness in studying interaction with immune cells.

Methods

After enzymatic digestion of first-trimester placental tissue from seven donors (6-9 weeks gestation) and trophoblast enrichment we cultured cytotrophoblasts (CTB) in stem cell medium. CTB were differentiated into EVT in a Matrigel-containing medium. A subset of CTB/EVT was profiled for microRNA levels. Expression of classical HLA molecules and of HLA-G was studied by flow cytometry, qPCR, and ELISA. Secondary trophoblast cell lines JAR and JEG-3 were studied as controls. Lymphocytes were investigated during co-culturing with EVT.

Results

The trophoblasts could be easily maintained for several passages, upregulated classical trophoblast markers (GATA3, TFAP2C, chromosome-19 microRNAs), and upon differentiation to EVT they were selective in expressing HLA-C. EVT showed increasing expression of total HLA-G, an increasing proportion of HLA-G1 over G2- and G3 isoforms, and elevated excretion of soluble HLA-G. These features were distinct from those of the secondary trophoblast cell lines. TNF-α and IL-8 represented the most abundantly secreted cytokines by CTB, but their levels were minimal in EVT cultures. As proof of principle, we showed that EVT affect lymphocytes in three-day co-cultures (n=4) by decreasing activation marker HLA-DR.

Conclusion

We verified the possibility culturing trophoblasts from first-term placentas, and their capability of differentiating to HLA-G expressing EVT. This culture model better represents the in-vivo situation than previously studied secondary trophoblast cell lines and enables mechanistic studies of fetal-maternal interactions.

The Role of Non-Coding RNAs in the Human Placenta

Non-coding RNAs (ncRNAs) play a central and regulatory role in almost all cells, organs, and species, which has been broadly recognized since the human ENCODE project and several other genome projects. Nevertheless, a small fraction of ncRNAs have been identified, and in the placenta they have been investigated very marginally. To date, most examples of ncRNAs which have been identified to be specific for fetal tissues, including placenta, are members of the group of microRNAs (miRNAs). Due to their quantity, it can be expected that the fairly larger group of other ncRNAs exerts far stronger effects than miRNAs. The syncytiotrophoblast of fetal origin forms the interface between fetus and mother, and releases permanently extracellular vesicles (EVs) into the maternal circulation which contain fetal proteins and RNA, including ncRNA, for communication with neighboring and distant maternal cells. Disorders of ncRNA in placental tissue, especially in trophoblast cells, and in EVs seem to be involved in pregnancy disorders, potentially as a cause or consequence. This review summarizes the current knowledge on placental ncRNA, their transport in EVs, and their involvement and pregnancy pathologies, as well as their potential for novel diagnostic tools.

A High-Throughput Toxicity Screen of 42 Per- and Polyfluoroalkyl Substances (PFAS) and Functional Assessment of Migration and Gene Expression in Human Placental Trophoblast Cells

Per- and polyfluoroalkyl substances (PFAS) have become ubiquitous environmental contaminants that have been associated with adverse pregnancy outcomes in women and experimental research models. Adverse developmental and reproductive outcomes have been investigated for relatively few PFAS, and such studies are not scalable to address the thousands of unique chemical structures. As the placenta has been reported as a PFAS target tissue, the human placental trophoblast JEG-3 cell line was employed in a high-throughput toxicity screen (HTTS) to evaluate the effects of 42 unique PFAS on viability, proliferation, and mitochondrial membrane potential (MMP). HTTS concentration-response curve fitting determined EC50 values for 79% of tested compounds for at least one of the three endpoints. Trophoblast migratory potential was evaluated for a subset of six prioritized PFAS using a scratch wound assay. Migration, measured as the percent of wound closure after 72 h, was most severely inhibited by exposure to 100 µM perfluorooctanoic acid (PFOA; 72% closure), perfluorooctanesulfonic acid (PFOS; 57% closure), or ammonium perfluoro-2-methyl-3-oxahexanoate (GenX; 79% closure). PFOA and GenX were subsequently evaluated for disrupted expression of 46 genes reported to be vital to trophoblast health. Disrupted regulation of oxidative stress was suggested by altered expression of GPEX1 (300 µM GenX and 3 µM GenX), GPER1 (300 µM GenX), and SOD1 and altered cellular response to xenobiotic stress was indicated by upregulation of the placental efflux transporter, ABCG2 (300 µM GenX, 3 µM GenX, and 100 µM PFOA). These findings suggest the placenta is potentially a direct target of PFAS exposure and indicate that trophoblast cell gene expression and function are disrupted at PFAS levels well below the calculated cytotoxicity threshold (EC50). Future work is needed to determine the mechanism(s) of action of PFAS towards placental trophoblasts.

miR-26a-5p and miR-125b-5p affect trophoblast genes and cell functions important during early pregnancy†

The most critical stage of pregnancy is embryo implantation, which relies on the synchronised developmental capacity of the embryo and uterine receptivity to implantation. In early pregnancy, conceptus and uterus release several factors enabling successful implantation and placentation. Molecules involved in embryo-maternal crosstalk include, but are not limited to, hormones, growth factors and cytokines. The discovery of microRNAs (miRNAs, small non-coding RNAs regulating gene expression) has revolutionized our understanding of many biological processes, including pregnancy. To date, numerous miRNAs have been detected in different species during pregnancy, both at the endometrial and embryonic sites. Thus, miRNAs are considered important regulators of early pregnancy events. Here, we report miR-26a-5p and miR-125b-5p effects on human and pig trophoblast cell function. Both miRNAs change the level of several genes and proteins important for proper embryo development. Moreover, miR-26a-5p stimulates porcine trophoblast proliferation and has a negative impact on its affinity to laminin. However, miR-125b-5p decreases porcine trophoblast cell migration. Our studies suggest that miR-26a-5p and miR-125b-5p can affect early pregnancy functions by regulating genes and processes important for proper conceptuses' development and progression through the implantation process.

Small Non-Coding RNAs in the Human Placenta: Regulatory Roles and Clinical Utility

The placenta is a vital organ formed during pregnancy, and being the interface between the mother and fetus, it is paramount that placental functioning is strictly controlled. Gene expression in the placenta is finely tuned-with aberrant expression causing placental pathologies and inducing stress on both mother and fetus. Gene regulation is brought upon by several mechanisms, and small non-coding RNAs (sncRNAs) have recently been appreciated for their contribution in gene repression. Their dysregulation has been implicated in a range of somatic and inherited disorders, highlighting their importance in maintaining healthy organ function. Their specific roles within the placenta, however, are not well understood, and require further exploration. To this end, we summarize the mechanisms of microRNAs (miRNAs), Piwi-interacting RNAs (piRNAs), small nuclear RNAs (snRNAs), small nucleolar RNAs (snoRNAs), and transfer RNAs (tRNAs), their known contributions to human placental health and disease, the relevance of sncRNAs as promising biomarkers throughout pregnancy, and the current challenges faced by placental sncRNA studies.

The Temporal Profile of Circulating miRNAs during Gestation in Overweight and Obese Women with or without Gestational Diabetes Mellitus

Circulating non-coding microRNAs (miRNAs) are important for placentation, but their expression profiles across gestation in pregnancies, which are complicated by gestational diabetes mellitus (GDM), have not been fully established. Investigating a single time point is insufficient, as pregnancy is dynamic, involving several processes, including placenta development, trophoblast proliferation and differentiation and oxygen sensing. Thus, the aim of this study was to compare the temporal expression of serum miRNAs in pregnant women with and without GDM. This is a nested case-control study of longitudinal data obtained from a multicentric European study (the ‘DALI’ study). All women (n = 82) were overweight/obese (BMI ≥ 29 kg/m²) and were normal glucose tolerant (NGT) at baseline (before 20 weeks of gestation). We selected women (n = 41) who were diagnosed with GDM at 24–28 weeks, according to the IADPSG/WHO2013 criteria. They were matched with 41 women who remained NGT in their pregnancy. miRNA (miR-16-5p, -29a-3p, -103-3p, -134-5p, -122-5p, -223-3p, -330-3p and miR-433-3p) were selected based on their suggested importance for placentation, and measurements were performed at baseline and at 24–28 and 35–37 weeks of gestation. Women with GDM presented with overall miRNA levels above those observed for women remaining NGT. In both groups, levels of miR-29a-3p and miR-134-5p increased consistently with progressing gestation. The change over time only differed for miR-29a-3p when comparing women with GDM with those remaining NGT (p = 0.044). Our findings indicate that among overweight/obese women who later develop GDM, miRNA levels are already elevated early in pregnancy and remain above those of women who remain NGT during their pregnancy. Maternal circulating miRNAs may provide further insight into placentation and the cross talk between the maternal and fetal compartments.

Preeclampsia, Natural History, Genes, and miRNAs Associated with the Syndrome

Preeclampsia (PE) is a hypertensive disease that affects pregnant women after 20 weeks of gestation. This disease is associated with an important risk of maternal and fetal mortality. PE is described as a placental pathology because, after delivery, most women recover normal arterial pressure. Poor invasion of the spiral arteries is a phenomenon well described in PE; this leads to a hypoxic uterine bed and imbalance of antiangiogenic and proangiogenic factors in the uteroplacental region, which in turn triggers the disease phenotype. The causes of the pathology are unclear; nevertheless, numerous approaches, including next-generation sequencing, association, and case control and miRNA studies, have shed light on the genetic/molecular basis of PE. These studies help us better understand the disease to advance new treatment strategies.

miR-6769b-5p targets CCND-1 to regulate proliferation in cadmium-treated placental trophoblasts: Association with the impairment of fetal growth

Environmental cadmium (Cd) is positively associated with placental impairment and fetal growth retardation. Nevertheless, its potential mechanisms remain unclear. microRNAs (miRNAs) are known to influence placental development and fetal growth. This work was aimed to determine which miRNAs are involved in Cd-impaired placental and fetal development based on the mRNA and miRNA expression profiles analysis. As a result, gestational Cd exposure deceased fetal and placental weight, and reduced the protein level of PCNA in human and mouse placentae. Furthermore, the results of mRNA microarray showed that Cd-downregulated mRNAs were predictively correlated with several biological processes, including cell proliferation, differentiation and motility. In addition, the results of miRNA microarray and qPCR assay demonstrated that Cd significantly increased the level of miR-6769b-5p, miR-146b-5p and miR-452-5p. Integrated analysis of Cd-upregulated miRNAs predicted target genes and Cd-downregulated mRNAs found that overlapping mRNAs, such as CCND1, CDK13, RINT1 and CDC26 were also significantly associated with cell proliferation. Further experiments showed that miR-6769b-5p inhibitor, but not miR-146b-5p and miR-452-5p, markedly reversed Cd-downregulated the expression of proliferation-related mRNAs, and thereby restored Cd-decreased the proteins level of CCND1 and PCNA in human placental trophoblasts. Dual luciferase reporter assay further revealed that miR-6769b-5p directly targets CCND1. Finally, the case-control study demonstrated that increased miR-6769b-5p level and impaired cell proliferation were observed in small-for-gestational-age human placentae. In conclusion, miR-6769b-5p targets CCND-1 to regulate proliferation in Cd-treated placental trophoblasts, which is associated with the impairment of fetal growth. Our findings imply that placental miR-6769b-5p may be used as an epigenetic marker for environmental pollutants-caused fetal growth restriction and its late-onset chronic diseases.

PM10 Alters Trophoblast Cell Function and Modulates miR-125b-5p Expression

Air pollution is one of the largest global environmental health hazards that threaten premature mortality or morbidity. Particulate matter 10 (PM10) has been demonstrated to contribute to several human diseases via dysregulated miRNA expression. Trophoblast cells play a key role in implantation and placentation for a successful pregnancy. Nonetheless, the PM10 associated trophoblast cell functions during pregnancy and miRNA expression are still unknown. Our study showed that PM10 affected HTR-8/SVneo cell viability and also decreased cell proliferation, migration, and invasion. A high concentration of PM10 caused an increase in HTR-8/SVneo cell apoptosis. Treatment with PM10 induced inflammation through the upregulated IL-1β, IL-6, and TNF-α expression in trophoblast cells. In PM10-treated HTR-8/SVneo cells, miR-125b-5p expression was considerably increased and TXNRD1 was found to be negatively related to miR-125b-5p. Collectively, our findings revealed that PM10 could alter miR-125b-5p expression by targeting TXNRD1 and suppressing trophoblast cell functions. Additional investigations relating to the function of miR-125b-5p and its target on particulate pollution exposure in trophoblast are warranted for future biomarker or effective therapeutic approaches.

Joan Hunt Senior award lecture: New tools to shed light on the 'black box' of pregnancy

Correct establishment of the placenta is critical to the success of a pregnancy, but many of the key events take place during or shortly after implantation and are inaccessible for study. This inaccessibility, coupled with the lack of a suitable preclinical animal model, means that knowledge of human early placental development and function is extremely limited. Hence, the first trimester is often referred to as the 'black box' of pregnancy. However, recent advances in the derivation of trophoblast stem cells and organoid cultures of the trophoblast and endometrium are opening new opportunities for basic and translational research, providing for the first time cells that faithfully replicate their tissue of origin and proliferate and differentiate in culture in a stable and reproducible manner. These cells are valuable new tools for investigating cell-lineage differentiation and maternal-fetal interactions, but become even more powerful when combined with advances in bioengineering, microfabrication and microfluidic technologies. Assembloids of the endometrium comprising various cell types as model systems to investigate events at implantation, and placentas-on-a-chip for the study of nutrient transfer or drug screening are just two examples. This is a rapidly advancing field that may usher in more personalised approaches to infertility and pregnancy complications. Many of the developments are still at the proof-of-principle phase, but with continued refinement they are likely to shed important light on events that are fundamental to our reproduction as individuals and as a species, yet for ethical reasons are hidden from view.

Placental extracellular vesicles-associated microRNA-519c mediates endotoxin adaptation in pregnancy

BACKGROUND

Pregnancy represents a unique challenge for the maternal-fetal immune interface, requiring a balance between immunosuppression, which is essential for the maintenance of a semiallogeneic fetus, and proinflammatory host defense to protect the maternal-fetal interface from invading organisms. Adaptation to repeated inflammatory stimuli (endotoxin tolerance) may be critical in preventing inflammation-induced preterm birth caused by exaggerated maternal inflammatory responses to mild or moderate infections that are common during pregnancy. However, the exact mechanisms contributing to the maintenance of tolerance to repeated infections are not completely understood. MicroRNAs play important roles in pregnancy with several microRNAs implicated in gestational tissue function and in pathologic pregnancy conditions. MicroRNA-519c, a member of the chromosome 19 microRNA cluster, is a human-specific microRNA mainly expressed in the placenta. However, its role in pregnancy is largely unknown.

OBJECTIVE

This study aimed to explore the role of "endotoxin tolerance" failure in the pathogenesis of an exaggerated inflammatory response often seen in inflammation-mediated preterm birth. In this study, we investigated the role of microRNA-519c, a placenta-specific microRNA, as a key regulator of endotoxin tolerance at the maternal-fetal interface.

STUDY DESIGN

Using a placental explant culture system, samples from term and second-trimester placentas were treated with lipopolysaccharide. After 24 hours, the conditioned media were collected for analysis, and the placental explants were re-exposed to repeated doses of lipopolysaccharide for 3 days. The supernatant was analyzed for inflammatory markers, the presence of extracellular vesicles, and microRNAs. To study the possible mechanism of action of the microRNAs, we evaluated the phosphodiesterase 3B pathway involved in tumor necrosis factor alpha production using a microRNA mimic and phosphodiesterase 3B small interfering RNA transfection. Finally, we analyzed human placental samples from different gestational ages and from women affected by inflammation-associated pregnancies.

RESULTS

Our data showed that repeated exposure of the human placenta to endotoxin challenges induced a tolerant phenotype characterized by decreased tumor necrosis factor alpha and up-regulated interleukin-10 levels. This reaction was mediated by the placenta-specific microRNA-519c packaged within placental extracellular vesicles. Lipopolysaccharide treatment increased the extracellular vesicles that were positive for the exosome tetraspanin markers, namely CD9, CD63, and CD81, and secreted primarily by trophoblasts. Primary human trophoblast cells transfected with a microRNA-519c mimic decreased phosphodiesterase 3B, whereas a lack of phosphodiesterase 3B, achieved by small interfering RNA transfection, led to decreased tumor necrosis factor alpha production. These data support the hypothesis that the anti-inflammatory action of microRNA-519c was mediated by a down-regulation of the phosphodiesterase 3B pathway, leading to inhibition of tumor necrosis factor alpha production. Furthermore, human placentas from normal and inflammation-associated pregnancies demonstrated that a decreased placental microRNA-519c level was linked to infection-induced inflammatory pathologies during pregnancy.

CONCLUSION

We identified microRNA-519c, a human placenta-specific microRNA, as a novel regulator of immune adaptation associated with infection-induced preterm birth at the maternal-fetal interface. Our study serves as a basis for future experiments to explore the potential use of microRNA-519c as a biomarker for infection-induced preterm birth.

δ-tocotrienol suppresses the migration and angiogenesis of trophoblasts in preeclampsia and promotes their apoptosis via miR-429/ ZEB1 axis

Preeclampsia (PE) is a severe medical disorder during pregnancy and there has been controversy about the effects of vitamin E on PE. This research intended to explore if δ-tocotrienol (δ-TT), an isomer of vitamin E, could impact PE. Preeclamptic and normal placentas were obtained and total RNA was extracted. The expression of different genes was analyzed through quantitative real-time polymerase chain reaction (qRT-PCR) and Pearson correlation analysis was conducted. After that, HTR-8/SVneo cells (human trophoblasts) were chosen and they were subjected to δ-tocotrienol treatment and then Cell Counting Kit-8 was used to test cell viability. To assess the effects of δ-TT on trophoblasts, wound healing assay and Transwell invasion assay were performed. How miR-429 interacts with ZEB1 was examined via dual luciferase reporter assay. Also, protein expression was evaluated via Western blotting. Our results have shown that δ-TT can impair the viability of trophoblasts and induce their apoptosis. Additionally, it can repress the growth, migration, epithelial-mesenchymal transition (EMT), invasion and angiogenesis in trophoblasts. Mechanistically, δ-TT exerts these effects on trophoblasts via downregulating miR-429 and upregulating ZEB1. Furthermore, miR-429 can bind ZEB1 directly. Clinical sample analysis has revealed that miR-429 expression in preeclamptic placenta is higher than that in normal placenta, but ZEB1 expression in preeclamptic placenta is downregulated. Also, there is a negative association between miR-429 and ZEB1 expression in preeclamptic placentas. These discoveries imply that δ-TT may be hazardous to pregnancy and should not be used in preeclamptic patients. In addition, targeting miR-429 might treat PE.

Sexually dimorphic patterns in maternal circulating microRNAs in pregnancies complicated by fetal growth restriction

Background

Current methods fail to accurately predict women at greatest risk of developing fetal growth restriction (FGR) or related adverse outcomes, including stillbirth. Sexual dimorphism in these adverse pregnancy outcomes is well documented as are sex-specific differences in gene and protein expression in the placenta. Circulating maternal serum microRNAs (miRNAs) offer potential as biomarkers that may also be informative of underlying pathology. We hypothesised that FGR would be associated with an altered miRNA profile and would differ depending on fetal sex.

Methods

miRNA expression profiles were assessed in maternal serum (> 36 weeks’ gestation) from women delivering a severely FGR infant (defined as an individualised birthweight centile (IBC) < 3rd) and matched control participants (AGA; IBC = 20–80th), using miRNA arrays. qPCR was performed using specific miRNA primers in an expanded cohort of patients with IBC < 5th (n = 15 males, n = 16 females/group). Maternal serum human placental lactogen (hPL) was used as a proxy to determine if serum miRNAs were related to placental dysfunction. In silico analyses were performed to predict the potential functions of altered miRNAs.

Results

Initial analyses revealed 11 miRNAs were altered in maternal serum from FGR pregnancies. In silico analyses revealed all 11 altered miRNAs were located in a network of genes that regulate placental function. Subsequent analysis demonstrated four miRNAs showed sexually dimorphic patterns. miR-28-5p was reduced in FGR pregnancies (p < 0.01) only when there was a female offspring and miR-301a-3p was only reduced in FGR pregnancies with a male fetus (p < 0.05). miR-454-3p was decreased in FGR pregnancies (p < 0.05) regardless of fetal sex but was only positively correlated to hPL when the fetus was female. Conversely, miR-29c-3p was correlated to maternal hPL only when the fetus was male. Target genes for sexually dimorphic miRNAs reveal potential functional roles in the placenta including angiogenesis, placental growth, nutrient transport and apoptosis.

Conclusions

These studies have identified sexually dimorphic patterns for miRNAs in maternal serum in FGR. These miRNAs may have potential as non-invasive biomarkers for FGR and associated placental dysfunction. Further studies to determine if these miRNAs have potential functional roles in the placenta may provide greater understanding of the pathogenesis of placental dysfunction and the differing susceptibility of male and female fetuses to adverse in utero conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00405-z.

Detection and treatment of pregnancies at high risk of fetal growth restriction (FGR) and stillbirth remains a major obstetric challenge; circulating maternal serum microRNAs (miRNAs) offer potential as novel biomarkers.

Unbiased analysis of serum miRNAs in women in late pregnancy identified a specific profile of circulating miRNAs in women with a growth-restricted infant.

Some altered miRNAs (miR-28-5p, miR-301a-3p) showed sexually dimorphic expression in FGR pregnancies and others a fetal-sex dependent association to a hormonal marker of placental dysfunction (miR-454-3p, miR-29c-3p).

miR-301a-3p and miR-28-5p could potentially be used to predict FGR specifically in pregnancies with a male or female baby, respectively, however larger cohort studies are required.

Further investigations of these miRNAs and their relationship to placental dysfunction will lead to a better understanding of the pathophysiology of FGR and why there is differing susceptibility of male and female fetuses to FGR and stillbirth.

Epigenetic processes during preeclampsia and effects on fetal development and chronic health

Preeclampsia (PE), the leading cause of maternal and fetal morbidity and mortality, is associated with poor fetal growth, intrauterine growth restriction (IUGR) and low birth weight (LBW). Offspring of women who had PE are at increased risk for cardiovascular (CV) disease later in life. However, the exact etiology of PE is unknown. Moreover, there are no effective interventions to treat PE or alleviate IUGR and the developmental origins of chronic disease in the offspring. The placenta is critical to fetal growth and development. Epigenetic regulatory processes such as histone modifications, microRNAs and DNA methylation play an important role in placental development including contributions to the regulation of trophoblast invasion and remodeling of the spiral arteries. Epigenetic processes that lead to changes in placental gene expression in PE mediate downstream effects that contribute to the development of placenta dysfunction, a critical mediator in the onset of PE, impaired fetal growth and IUGR. Therefore, this review will focus on epigenetic processes that contribute to the pathogenesis of PE and IUGR. Understanding the epigenetic mechanisms that contribute to normal placental development and the initiating events in PE may lead to novel therapeutic targets in PE that improve fetal growth and mitigate increased CV risk in the offspring.

Placental expression of miR-21-5p, miR-210-3p and miR-141-3p: relation to human fetoplacental growth

BACKGROUND/OBJECTIVES

Dysregulation of microRNAs (miRNAs) and their target genes in placental tissue is associated with foetal growth restriction. We aimed to evaluate associations of placental miR-21-5p, miR-141-3p and miR-210-3p expression with maternal, placental and newborn parameters and with placental expression of their potential target genes PTEN, VEGF, FLT and ENG in a set of well-characterized small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies.

SUBJECTS/METHODS

Placental samples (n = 80) from 26 SGA and 54 AGA were collected from full-term singleton pregnancies. Placental transcript abundances of miR-21-5p, miR-141-3p and miR-210-3p were assessed after normalization to a reference miRNA, mir-16-5p by real-time quantitative PCR. Placental transcript abundances of PTEN, VEGF, FLT and ENG were assessed after normalizing to a panel of reference genes.

RESULTS

Placental miR-21-5p transcript abundance was negatively associated with placental weight (n = 80, r = -0.222, P = 0.047) and this association was specific to the AGA births (n = 54, r = -0.292, P = 0.032). Placental transcript abundances of miR-210-3p and miR-141-3p were not associated with placental weight or birth weight in all 80 births. However, placental miR-210-3p transcript abundance was positively associated with birth weight specifically in the SGA births (n = 26, r = 0.449, P = 0.021). Placental transcript abundance of miR-21-5p was negatively associated with PTEN transcript abundance (Spearman's ρ = -0.245, P = 0.028) while that of miR-141-3p was positively associated with FLT (Spearman's ρ = 0.261, P = 0.019) and ENG (Spearman's ρ = 0.259, P = 0.020) transcript abundances in all 80 births.

CONCLUSION

We conclude that placental miR-21-5p and miR-210-3p may be involved in fetoplacental growth. However, this regulation is unlikely to be mediated through placental expression of PTEN, VEGF, FLT or ENG.

Non-Coding RNAs in Preeclampsia-Molecular Mechanisms and Diagnostic Potential

Preeclampsia (PE) is a leading cause of maternal and neonatal morbidity and mortality worldwide. Defects in trophoblast invasion, differentiation of extravillous trophoblasts and spiral artery remodeling are key factors in PE development. Currently there are no predictive biomarkers clinically available for PE. Recent technological advancements empowered transcriptome exploration and led to the discovery of numerous non-coding RNA species of which microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the most investigated. They are implicated in the regulation of numerous cellular functions, and as such are being extensively explored as potential biomarkers for various diseases. Altered expression of numerous lncRNAs and miRNAs in placenta has been related to pathophysiological processes that occur in preeclampsia. In the following text we offer summary of the latest knowledge of the molecular mechanism by which lnRNAs and miRNAs (focusing on the chromosome 19 miRNA cluster (C19MC)) contribute to pathophysiology of PE development and their potential utility as biomarkers of PE, with special focus on sample selection and techniques for the quantification of lncRNAs and miRNAs in maternal circulation.

Placental expression of RNU44, RNU48 and miR-16-5p: stability and relations with fetoplacental growth

BACKGROUND/OBJECTIVES

The current study aimed to identify suitable reference miRNA for placental miRNA expression analysis in a set of well-characterized and fetal-sex balanced small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies.

SUBJECTS/METHODS

In this retrospective study, placental samples (n = 106) from 35 SGA (19 male and 16 female) and 71 AGA (30 male and 41 female) full-term singleton pregnancies were utilized. Placental transcript abundance of three widely used reference miRNAs [miR-16-5p and Small nucleolar RNAs (snoRNAs) RNU44 and RNU48] were assessed by real-time quantitative PCR. Raw cycle threshold (C_t) analysis and RefFinder tool analysis were conducted for evaluating stability of expression of these miRNAs.

RESULTS

Raw C_t values of miR-16-5p were similar between SGA and AGA births (P = 0.140) and between male and female births within SGA (P = 0.159) and AGA (P = 0.060) births while that of RNU44 and RNU48 were higher in SGA births (P = 0.008 and 0.006 respectively) and in male births within the SGA group (P = 0.005) for RNU44 and in female births within the AGA group (P = 0.048) for RNU48. Across all 106 samples tested using the RefFinder tool, miR-16-5p and RNU44 were equally stable reference miRNAs.

CONCLUSION

We recommend miR-16-5p and RNU44 as suitable reference miRNAs for placental samples from settings similar to our study.

Large-scale transcriptome-wide profiling of microRNAs in human placenta and maternal plasma at early to mid gestation

MicroRNAs (miRNAs) are increasingly seen as important regulators of placental development and opportunistic biomarker targets. Given the difficulty in obtaining samples from early gestation and subsequent paucity of the same, investigation of the role of miRNAs in early gestation human placenta has been limited. To address this, we generated miRNA profiles using 96 placentas from presumed normal pregnancies, across early gestation, in combination with matched profiles from maternal plasma. Placenta samples range from 6 to 23 weeks' gestation, a time period that includes placenta from the early, relatively low but physiological (6-10 weeks' gestation) oxygen environment, and later, physiologically normal oxygen environment (11-23 weeks' gestation).We identified 637 miRNAs with expression in 86 samples (after removing poor quality samples), showing a clear gestational age gradient from 6 to 23 weeks' gestation. We identified 374 differentially expressed (DE) miRNAs between placentas from 6-10 weeks' versus 11-23 weeks' gestation. We see a clear gestational age group bias in miRNA clusters C19MC, C14MC, miR-17 ~ 92 and paralogs, regions that also include many DE miRNAs. Proportional change in expression of placenta-specific miRNA clusters was reflected in maternal plasma.The presumed introduction of oxygenated maternal blood into the placenta (between ~10 and 12 weeks' gestation) changes the miRNA profile of the chorionic villus, particularly in placenta-specific miRNA clusters. Data presented here comprise a clinically important reference set for studying early placenta development and may underpin the generation of minimally invasive methods for monitoring placental health.

Exercise during Pregnancy: Developmental Programming Effects and Future Directions in Humans

Epidemiological studies show that low birth weight is associated with mortality from cardiovascular disease in adulthood, indicating that chronic diseases could be influenced by hormonal or metabolic insults encountered in utero. This concept, now known as the Developmental Origins of Health and Disease hypothesis, postulates that the intrauterine environment may alter the structure and function of the organs of the fetus as well as the expression of genes that impart an increased vulnerability to chronic diseases later in life. Lifestyle interventions initiated during the prenatal period are crucial as there is the potential to attenuate progression towards chronic diseases. However, how lifestyle interventions such as physical activity directly affect human offspring metabolism and the potential mechanisms involved in regulating metabolic balance at the cellular level are not known. The purpose of this review is to highlight the effects of exercise during pregnancy on offspring metabolic health and emphasize gaps in the current human literature and suggestions for future research.

Placental outcomes of phthalate exposure

Proper placental development and function relies on hormone receptors and signaling pathways that make the placenta susceptible to disruption by endocrine disrupting chemicals, such as phthalates. Here, we review relevant research on the associations between phthalate exposures and dysfunctions of the development and function of the placenta, including morphology, physiology, and genetic and epigenetic effects. This review covers in vitro studies, in vivo studies in mammals, and studies in humans. We also discuss important gaps in the literature. Overall, the evidence indicates that toxicity to the placental and maternal-fetal interface is associated with exposure to phthalates. Further studies are needed to better elucidate the mechanisms through which phthalates act in the placenta as well as additional human studies that assess placental disruption through pregnancy with larger sample sizes.

High-throughput miRNA sequencing of the human placenta: expression throughout gestation

Aim: To understand miRNA changes across gestation in healthy human placentae. This is essential before miRNAs can be used as biomarkers or prognostic indicators during pregnancy. Materials & methods: Using next-generation sequencing, we characterize the normative human placenta miRNome in first (n = 113) and third trimester (n = 47). Results & conclusion: There are 801 miRNAs expressed in both first and third trimester, including 182 with similar expression across gestation (p ≥ 0.05, fold change ≤2) and 180 significantly different (false discovery rate <0.05, fold change >2). Of placenta-specific miRNA clusters, chromosome 14 miRNA cluster decreases across gestation and chromosome 19 miRNA cluster is overall highly expressed. Chromosome 13 clusters are upregulated in first trimester. This work provides a rich atlas of healthy pregnancies to direct functional studies investigating the epigenetic differences in first and third trimester placentae.

Bioinformatics Analysis of Choriocarcinoma-Related MicroRNA-Transcription Factor-Target Gene Regulatory Networks and Validation of Key miRNAs

Objective

The aim of the current research was to construct a miRNA-transcription factor (TF)-target gene regulatory network in order to investigate the mechanism underlying choriocarcinoma and to verify the network through the overexpression or silencing of hub miRNAs in vitro.

Materials and Methods

A mRNA expression dataset and two miRNA expression datasets were analysed to identify differentially expressed genes (DEGs) and miRNAs (DEMs) between normal cells and choriocarcinoma cells. The top 400 upregulated and downregulated DEGs were identified as candidate DEGs, which were then mapped to construct protein–protein interaction (PPI) networks and select hub genes. Moreover, the DGIdb database was utilized to select candidate drugs for hub genes. Moreover, DEM target genes were predicted through the miRWalk2.0 database and overlaid with candidate DEGs to identify the differentially expressed target genes (DETGs). Furthermore, we established miRNA-TF-target gene regulatory networks and performed functional enrichment analysis of hub DEMs. Finally, we transfected mimics or inhibitors of hub DEMs into choriocarcinoma cells and assessed cell proliferation and migration to verify the vital role of hub DEMs in choriocarcinoma.

Results

A total of 140 DEMs and 400 candidate DEGs were screened from choriocarcinoma cells and normal cells. A PPI network of 400 candidate DEGs was established. Twenty-nine hub genes and 99 associated small molecules were identified to provide potential target drugs for choriocarcinoma treatment. We obtained 70 DETGs of DEMs derived from the intersection between predicted miRNA target genes and candidate DEGs. Subsequently, 3 hub DEMs were selected, and miRNA-TF-target gene regulatory networks containing 4 TFs, 3 TFs and 3 TFs for each network were constructed. The RT-PCR results confirmed that miR-29b-3p was highly expressed and that miR-519c-3p and miR-520a-5p were expressed at low levels in choriocarcinoma cells. The overexpression or silencing results suggested that 3 dysregulated hub DEMs jointly accelerated the proliferation and migration of choriocarcinoma.

Conclusion

Association of miRNA-TF-target gene regulatory networks may help us explore the underlying mechanism and provide potential targets for the diagnosis and treatment of choriocarcinoma.

Loss of Selenoprotein Iodothyronine Deiodinase 3 Expression Correlates with Progression of Complete Hydatidiform Mole to Gestational Trophoblastic Neoplasia

To investigate if differences in imprinting at tropho-microRNA (miRNA) genomic clusters can distinguish between pre-gestational trophoblastic neoplasia cases (pre-GTN) and benign complete hydatidiform mole (CHM) cases at the time of initial uterine evacuation. miRNA sequencing was performed on frozen tissue from 39 CHM cases including 9 GTN cases. DIO3, DLK1, RTL1, and MEG 3 mRNA levels were assessed by qRT-PCR. Protein abundance was assessed by Western blot for DIO3, DLK1, and RTL1. qRT-PCR and Western blot were performed for selenoproteins and markers of oxidative stress. Immunohistochemistry (IHC) was performed for DIO3 on an independent validation set of clinical samples (n = 42) and compared to normal placenta controls across gestational ages. Relative expression of the 14q32 miRNA cluster was lower in pre-GTN cases. There were no differences in protein abundance of DLK1 or RTL1. Notably, there was lower protein expression of DIO3 in pre-GTN cases (5-fold, p < 0.03). There were no differences in mRNA levels of DIO3, DLK1, RTL1 or MEG 3. mRNA levels were higher in all CHM cases compared to normal placenta. IHC showed syncytiotrophoblast-specific DIO3 immunostaining in benign CHM cases and normal placenta, while pre-GTN cases of CHM lacked DIO3 expression. We describe two new biomarkers of pre-GTN CHM cases: decreased 14q32 miRNA expression and loss of DIO3 expression by IHC. Differences in imprinting between benign CHM and pre-GTN cases may provide insight into the fundamental development of CHM.

Angiogenic Properties of Placenta-Derived Extracellular Vesicles in Normal Pregnancy and in Preeclampsia

Angiogenesis is one of the main processes that coordinate the biological events leading to a successful pregnancy, and its imbalance characterizes several pregnancy-related diseases, including preeclampsia. Intracellular interactions via extracellular vesicles (EVs) contribute to pregnancy's physiology and pathophysiology, and to the fetal-maternal interaction. The present review outlines the implications of EV-mediated crosstalk in the angiogenic process in healthy pregnancy and its dysregulation in preeclampsia. In particular, the effect of EVs derived from gestational tissues in pro and anti-angiogenic processes in the physiological and pathological setting is described. Moreover, the application of EVs from placental stem cells in the clinical setting is reported.

Considerations to Model Heart Disease in Women with Preeclampsia and Cardiovascular Disease

Preeclampsia is a multifactorial cardiovascular disorder diagnosed after 20 weeks of gestation, and is the leading cause of death for both mothers and babies in pregnancy. The pathophysiology remains poorly understood due to the variability and unpredictability of disease manifestation when studied in animal models. After preeclampsia, both mothers and offspring have a higher risk of cardiovascular disease (CVD), including myocardial infarction or heart attack and heart failure (HF). Myocardial infarction is an acute myocardial damage that can be treated through reperfusion; however, this therapeutic approach leads to ischemic/reperfusion injury (IRI), often leading to HF. In this review, we compared the current in vivo, in vitro and ex vivo model systems used to study preeclampsia, IRI and HF. Future studies aiming at evaluating CVD in preeclampsia patients could benefit from novel models that better mimic the complex scenario described in this article.