MicroRNA-218-5p Promotes Endovascular Trophoblast Differentiation and Spiral Artery Remodeling

Advances in pathogenesis of preeclampsia

PURPOSE

Preeclampsia is a major cause of health problems for both pregnant women and unborn babies worldwide. However, the underlying causes of preeclampsia are not fully understood, leading to limited effective treatments. The goal of this study is to enhance our knowledge of its causes, devise prevention strategies, and develop treatments.

METHODS

We performed a systematic literature search. Six models regarding the pathogenesis of preeclampsia are discussed in this review.

RESULTS

This review focuses on the latest advancements in understanding preeclampsia's origins. Preeclampsia is a complex condition caused by various factors, processes, and pathways. Reduced blood flow and oxygen to the uterus and placenta, heightened inflammatory reactions, immune imbalances, altered genetic changes, imbalanced blood vessel growth factors, and disrupted gut bacteria may contribute to its development.

CONCLUSION

Preeclampsia is thought to result from the interplay of these factors.

Association between CORIN promoter methylation and hypertensive disorders of pregnancy - A nested case-control study

INTRODUCTION

Corin protein and its coding gene variants have been associated with hypertensive disorders of pregnancy (HDP), but the underlying mechanisms are unclear. As a mediator linking fixed genome with the dynamic environment, DNA methylation at the CORIN gene may link corin with HDP but not has been studied. This study aimed to examine whether CORIN promoter methylation and HDP in Chinese pregnant women.

METHODS

Based on a cohort of Chinese pregnant women, we designed a nested case-control study including 196 cases with HDP and 200 healthy controls. DNA methylation levels in the CORIN promoter were quantified by pyrosequencing using peripheral blood before 20 gestational weeks. The association between DNA methylation in CORIN promoter and HDP was systemically examined by single CpG association analysis, followed by gene-based analysis. Multiple testing was controlled by the false discovery rate (FDR) method.

RESULTS

The single CpG association analysis found that, among the 5 CpG sites assayed, hypermethylation at one CpG site (Chr4:47839945) was significantly associated with HDP (OR = 1.94, raw P = 0.020), but the significance did not survive for multiple testing correction (FDR-P = 0.100). The gene-based association analysis found that DNA methylation of the 5 CpG sites was jointly associated with HDP (raw P = 0.003). In addition to HDP, CORIN promoter methylation was also significantly associated with dynamic blood pressure during pregnancy (raw P < 0.05).

DISCUSSION

Hypermethylation in CORIN promoter at early pregnancy was associated with the risk of HDP during late pregnancy in Chinese women. However, further evidence is required to establish the causality between CORIN promoter methylation and HDP.

Unraveling the molecular mechanisms driving enhanced invasion capability of extravillous trophoblast cells: a comprehensive review

Precise extravillous trophoblast (EVT) invasion is crucial for successful placentation and pregnancy. This review focuses on elucidating the mechanisms that promote heightened EVT invasion. We comprehensively summarize the pivotal roles of hormones, angiogenesis, hypoxia, stress, the extracellular matrix microenvironment, epithelial-to-mesenchymal transition (EMT), immunity, inflammation, programmed cell death, epigenetic modifications, and microbiota in facilitating EVT invasion. The molecular mechanisms underlying enhanced EVT invasion may provide valuable insights into potential pathogenic mechanisms associated with diseases characterized by excessive invasion, such as the placenta accreta spectrum (PAS), thereby offering novel perspectives for managing pregnancy complications related to deficient EVT invasion.

Visual identification of three kinds of human decidual tissues from elective termination of pregnancy

INTRODUCTION

The decidua can be classified into the decidua basalis, decidua capsularis and decidua parietalis. This study aimed to visually identify these three kinds of decidual tissues from fresh samples obtained in early pregnancy based on their macroscopic appearances, which can be discerned visually.

METHODS

Decidual samples were collected from 15 pregnant women between 6 and 8 weeks of gestation after elective termination of pregnancy. We identified the three different kinds of fresh decidual tissues in early pregnancy according to their different macroscopic appearances by only the naked eye. H&E staining, in situ immunofluorescence and flow cytometry were performed to confirm the accuracy of this method.

RESULTS

We developed a method to discern the three different kinds of decidual tissues according to their individual macroscopic features. We found that the decidua parietalis was a thick tissue with less blood, with one side being intact epidermis and the other side being rough tissue. The decidua basalis had rough surfaces, a dense texture and high blood content. The decidua capsularis was a thin membrane tissue with or without blood clots. CK+/HLA-G+ extravillous trophoblast cells (EVTs) and heme oxygenase-1+ (HMOX1+) decidual macrophages were present in large quantities in the decidua basalis and decidua capsularis but were nearly undetectable in the decidua parietalis. We also found a wide distribution of endovascular extravillous trophoblast cells (enEVTs), which participate in spiral artery remodelling in the decidua basalis.

DISCUSSION

We successfully identified three kinds of human decidual tissues from early pregnancy with the naked eye for the first time. This breakthrough method will greatly assist studies related to decidua during early pregnancy.

Exploring maternal-fetal interface with in vitro placental and trophoblastic models

The placenta, being a temporary organ, plays a crucial role in facilitating the exchange of nutrients and gases between the mother and the fetus during pregnancy. Any abnormalities in the development of this vital organ not only lead to various pregnancy-related disorders that can result in fetal injury or death, but also have long-term effects on maternal health. In vitro models have been employed to study the physiological features and molecular regulatory mechanisms of placental development, aiming to gain a detailed understanding of the pathogenesis of pregnancy-related diseases. Among these models, trophoblast stem cell culture and organoids show great promise. In this review, we provide a comprehensive overview of the current mature trophoblast stem cell models and emerging organoid models, while also discussing other models in a systematic manner. We believe that this knowledge will be valuable in guiding further exploration of the complex maternal-fetal interface.

MiR-218-5p promotes trophoblast infiltration and inhibits endoplasmic reticulum/oxidative stress by reducing UBE3A-mediated degradation of SATB1

This research evaluated the effects of miR-218-5p on trophoblast infiltration and endoplasmic reticulum/oxidative stress during preeclampsia (PE). The expression of miR-218-5p and special AT-rich sequence binding protein 1 (SATB1) in placental tissues from 25 patients with PE and 25 normal pregnant subjects was determined using qRT-PCR and western blotting. Cell invasion and cell migration were detected by performing Transwell assays and scratch assays, respectively. MMP-2/9, TIMP1/2, HIF-1α, p-eIF2α, and ATF4 expression in cells was assessed through western blotting. Intracellular reactive oxygen species were detected using 2,7-dichlorodihydrofluorescein diacetate, and intracellular malondialdehyde and superoxide dismutase activities were determined with kits. Dual-luciferase and RNA pull-down assays were performed to verify the interaction between miR-218-5p and UBE3A. Co-immunoprecipitation and western blotting were used to detect the ubiquitination levels of SATB1. A rat model of PE was established, and an miR-218-5p agomir was injected into rat placental tissues. The pathological characteristics of placental tissues were detected via HE staining, and MMP-2/9, TIMP1/2, p-eIF2α, and ATF4 expression in rat placental tissues was determined through western blotting. MiR-218-5p and SATB1 were expressed at low levels, while UBE3A was highly expressed in the placental tissues of patients with PE. The transfection of an miR-218-5p mimic, UBE3A shRNA, or an SATB1 overexpression vector into HTR-8/SVneo cells promoted trophoblast infiltration and inhibited endoplasmic reticulum/oxidative stress. It was determined that UBE3A is a target of miR-218-5p; UBE3A induces ubiquitin-mediated degradation of SATB1. In PE model rats, miR-218-5p alleviated pathological features, promoted trophoblast infiltration, and inhibited endoplasmic reticulum/oxidative stress. MiR-218-5p targeted and negatively regulated UBE3A expression to inhibit ubiquitin-mediated SATB1 degradation, promote trophoblast infiltration, and inhibit endoplasmic reticulum/oxidative stress.

Effects of Gestational Arsenic Exposures on Placental and Fetal Development in Mice: The Role of Cyr61 m6A

BACKGROUND

Several epidemiological investigations demonstrated that maternal arsenic (As) exposure elevated risk of fetal growth restriction (FGR), but the mechanism remains unclear.

OBJECTIVES

This study aimed to investigate the effects of gestational As exposure on placental and fetal development and its underlying mechanism.

METHODS

Dams were exposed to 0.15, 1.5, and 15 mg / L NaAsO 2 throughout pregnancy via drinking water. Sizes of fetuses and placentas, placental histopathology, and glycogen content were measured. Placental RNA sequencing was conducted. Human trophoblasts were exposed to NaAsO 2 (2 μ M ) to establish an in vitro model of As exposure. The mRNA stability and protein level of genes identified through RNA sequencing were measured. N 6 -Methyladenosine (m 6 A ) modification was detected by methylated RNA immunoprecipitation-quantitative real-time polymerase chain reason (qPCR). The binding ability of insulin-like growth factor 2 binding protein 2 to the gene of interest was detected by RNA-binding protein immunoprecipitation-qPCR. Intracellular S-adenosylmethionine (SAM) and methyltransferase activity were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and colorimetry, respectively. In vitro As + 3 methyltransferase (As3MT) knockdown or SAM supplementation and in vivo folic acid (FA) supplementation were used to evaluate the protective effect. A case-control study verified the findings.

RESULTS

Sizes of fetuses (exposed to 1.5 and 15 mg / L NaAsO 2 ) and placentas (exposed to 15 mg / L NaAsO 2 ) were lower in As-exposed mice. More glycogen + trophoblasts accumulated and the expression of markers of interstitial invasion was lower in the 15 mg / L NaAsO 2 -exposed mouse group in comparison with control. Placental RNA sequencing identified cysteine-rich angiogenic inducer 61 (Cyr61) as a candidate gene of interest. Mechanistically, mice and cells exposed to As had lower protein expression of CYR61, and this was attributed to a lower incidence of Cyr61 m 6 A . Furthermore, cells exposed to As had lower methyltransferase activity, suggesting that this could be the mechanism by which Cyr61 m 6 A was affected. Depletion of intracellular SAM, a cofactor for m 6 A methyltransferase catalytic domain, partially contributed to As-induced methyltransferase activity reduction. Either As3MT knockdown or SAM supplementation attenuated As-induced Cyr61 m 6 A down-regulation. In mice, FA supplementation rescued As-induced defective trophoblastic invasion and FGR. In humans, a negative correlation between maternal urinary As and plasma CYR61 was observed in infants who were small for gestational age.

DISCUSSION

Using in vitro and in vivo models, we found that intracellular SAM depletion-mediated Cyr61 m 6 A down-regulation partially contributed to As-induced defective trophoblastic invasion and FGR. https://doi.org/10.1289/EHP12207.

Trophoblast Differentiation: Mechanisms and Implications for Pregnancy Complications

Placental development is a tightly controlled event, in which cell expansion from the trophectoderm occurs in a spatiotemporal manner. Proper trophoblast differentiation is crucial to the vitality of this gestational organ. Obstructions to its development can lead to pregnancy complications, such as preeclampsia, fetal growth restriction, and preterm birth, posing severe health risks to both the mother and offspring. Currently, the only known treatment strategy for these complications is delivery, making it an important area of research. The aim of this review was to summarize the known information on the development and mechanistic regulation of trophoblast differentiation and highlight the similarities in these processes between the human and mouse placenta. Additionally, the known biomarkers for each cell type were compiled to aid in the analysis of sequencing technologies.

The effect of MicroRNAs variants on idiopathic recurrent pregnancy loss

BACKGROUND

Although the importance of miRNA variants in female reproductive disorders has been frequently reported, the association between miRNA polymorphisms and recurrent pregnancy loss (RPL) has been poorly studied. In this study, we aimed to assess the correlation of four different miRNA variants to unexplained RPL.

METHODS AND RESULTS

The prevalence of four SNPs including miR-21 rs1292037, miR-155-5p rs767649, miR-218-2 rs11134527, and miR-605 rs2043556 in 280 cases with iRPL and 280 controls was performed. The DNA was extracted from all subjects and the SNPs were genotyped using RFLP-PCR methods. The data revealed that rs1292037 and rs767649 were significantly associated with higher rates of iRPL in patients compared with controls while rs11134527 and rs2043556 showed no association with increased rates of iRPL among patients. The haplotypes T-A-G-G and T-A-G-A were the most frequent in both cases and controls. Three haplotypes including T-T-G-A, C-T-G-G, and T-A-A-A showed significantly different frequencies in patients in comparison to healthy females.

CONCLUSION

This study suggests that rs1292037 and rs767649 could be risk factors for increased rates of iRPL.

Emerging role of miRNAs, lncRNAs, and circRNAs in pregnancy-associated diseases

ABSTRACT

Accumulating studies have demonstrated that non-coding RNAs (ncRNAs), functioning as important regulators of transcription and translation, are involved in the establishment and maintenance of pregnancy, especially the maternal immune adaptation process. The endometrial stromal cells (ESCs), trophoblast cells, and decidua immune cells that reside at the maternal-fetal interface are thought to play significant roles in normal pregnancy and pregnancy-associated diseases. Here, we reviewed the up-to-date evidence on how microRNA, long non-coding RNA, and circular RNA regulate ESCs, trophoblast cells, and immune cells and discussed the potential applications of these ncRNAs as diagnostic and therapeutic markers in pregnancy complications.

Hsa_circ_0001326 inhibited the proliferation, migration, and invasion of trophoblast cells via miR-145-5p/TGFB2 axis

PROBLEM

Preeclampsia (PE) is an obstetric disease involving multiple systems, which account for maternal and fetal complications and increased mortality. Circular RNAs (circRNAs) were recently deemed to associate with the pathogenesis of PE. This study aims to clarify the correlation between circRNA hsa_circ_0001326 and PE and explore its biological function in PE.

METHOD OF STUDY

The expression of hsa_circ_0001326 in PE placentas was detected by real-time quantitative PCR (qRT-PCR). After overexpressing or inhibiting hsa_circ_0001326 in trophoblast cells, the cell growth, migration, and invasion were evaluated by Cell Counting Kit-8 (CCK-8) and transwell assays. Western blot assay was applied to detect the epithelial-mesenchymal transition (EMT) proteins, E-cadherin and Vimentin. Furthermore, a dual-luciferase reporter assay was applied to verify the binding sites of hsa_circ_0001326, miR-145-5p, and transforming growth factor beta 2 (TGFB2).

RESULTS

Hsa_circ_0001326 was found to be higher expressed in PE placentas than in normal placentas. Furthermore, hsa_circ_0001326 played a negative regulating role in trophoblast cell viability, migration, and invasion. Overexpression of hsa_circ_0001326 inhibited the viability, migration, and invasion of trophoblast cells, while inhibition of hsa_circ_0001326 showed opposite effects. Mechanistically, hsa_circ_0001326 sponged miR-145-5p to elevate TGFB2 expression in trophoblast cells.

CONCLUSION

This study provided evidence that the up-regulated hsa_circ_0001326 in PE restrained trophoblast cells proliferation, migration, and invasion by sponging miR-145-5p to elevate TGFB2 expression. Our results might provide a novel insight into the role of hsa_circ_0001326 in the pathogenesis of PE.

Ultrasound and microbubble-mediated delivery of miR-424-5p has a therapeutic effect in preeclampsia

OBJECTIVE

To determine the influence of ultrasound/microbubble-mediated miR-424-5p delivery on trophoblast cells and the underlying mechanism.

METHODS

Blood pressure and 24-h proteinuria of patients with preeclampsia (PE) were measured as well as the levels of miR-424-5p and amine oxidase copper containing 1 (AOC1) in placental tissues. HTR-8/Svneo and TEV-1 cells were subjected to cell transfection or ultrasonic microbubble transfection for determination of the expression of miR-424-5p, AOC1, β-catenin and c-Myc as well as cell proliferation, apoptosis, migration and invasiveness. The concentrations of placental growth factor (PLGF), human chorionic gonadotropin (β-hCG) and tumor necrosis factor-α (TNF-α) were measured in HTR-8/Svneo and TEV-1 cells. RNA immunoprecipitation (RIP) and dual luciferase reporter assay detected the binding of miR-424-5p to AOC1. A PE mouse model was induced by subcutaneous injection of L-NAME, where the influence of ultrasound/microbubble-mediated miR-424-5p delivery was evaluated.

RESULTS

miR-424-5p was downregulated while AOC1 was upregulated in the placental tissues from PE patients. Overexpression of miR-424-5p activated Wnt/β-catenin signaling pathway and promoted the proliferation of HTR-8/Svneo and TEV-1 cells as well as enhanced the migratory and invasive behaviors. AOC1 overexpression partly eliminated the effects of miR-424-5p on HTR-8/Svneo and TEV-1 cells. Ultrasound and microbubble mediated gene delivery enhanced the transfection efficiency of miR-424-5p and further promoted the effects of miR-424-5p in trophoblast cells. Ultrasound/microbubble-mediated miR-424-5p delivery alleviated experimental PE in mice.

CONCLUSION

Ultrasound and microbubble-mediated miR-424-5p delivery targets AOC1 and activates Wnt/β-catenin signaling pathway, thus promoting the aggressive phenotype of trophoblast cells, which indicating that miR-424-5p/AOC1 axis might be involved with PE pathogenesis.

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.

Hyperglycemia disturbs trophoblast functions and subsequently leads to failure of uterine spiral artery remodeling

Uterine spiral artery remodeling is necessary for fetal growth and development as well as pregnancy outcomes. During remodeling, trophoblasts invade the arteries, replace the endothelium and disrupt the vascular smooth muscle, and are strictly regulated by the local microenvironment. Elevated glucose levels at the fetal-maternal interface are associated with disorganized placental villi and poor placental blood flow. Hyperglycemia disturbs trophoblast proliferation and invasion via inhibiting the epithelial-mesenchymal transition, altering the protein expression of related proteases (MMP9, MMP2, and uPA) and angiogenic factors (VEGF, PIGF). Besides, hyperglycemia influences the cellular crosstalk between immune cells, trophoblast, and vascular cells, leading to the failure of spiral artery remodeling. This review provides insight into molecular mechanisms and signaling pathways of hyperglycemia that influence trophoblast functions and uterine spiral artery remodeling.

The crucial role of LncRNA MIR210HG involved in the regulation of human cancer and other disease

Long noncoding RNAs (lncRNAs) have evoked considerable interest in recent years due to their critical functions in the regulation of disease processes. Abnormal expression of lncRNAs is found in multiple diseases, and lncRNAs have been exploited for diverse medical applications. The lncRNA MIR210HG is a recently discovered lncRNA that is widely dysregulated in human disease. MIR210HG was described to have biological functions with potential roles in disease development, including cell proliferation, invasion, migration, and energy metabolism. And MIR210HG dysregulation was confirmed to have promising clinical values in disease diagnosis, treatment, and prognosis. In this review, we systematically summarize the expression profiles, roles, underlying mechanisms, and clinical applications of MIR210HG in human disease.

miR-372-3p promotes preeclampsia progression by regulating twist1

Preeclampsia (PE) is a common pregnancy-related disorder worldwide. PE is mainly characterized by the defective migration and invasion of trophoblast cells. MicroRNAs (miRs) have been reported to serve an important role in PE. The purpose of the study was to explore the pathogenesis and therapeutic targets of preeclampsia. In the present study, reverse transcription-quantitative PCR analysis revealed that the expression levels of miR-372-3p were upregulated in placental tissues from patients with PE. Notably, the expression levels of miR-372-3p were significantly upregulated in patients with early-onset PE compared with patients with late-onset PE. Moreover, in vitro analysis using wound healing, Transwell and western blotting assays demonstrated that miR-372-3p overexpression inhibited the migration, invasion and epithelial-mesenchymal transition (EMT) of HTR-8/SVneo trophoblast cells, respectively. Bioinformatics analysis and a dual luciferase reporter assay revealed that miR-372-3p is sponged by twist family bHLH transcription factor 1 (twist1). Rescue experiments found that miR-372-3p overexpression suppressed trophoblast cell migration, invasion and EMT by downregulating the expression of twist1. In conclusion, the present study revealed that high level of miR-372-3p may act as a factor to cause PE and may also be a potential novel therapeutic target for 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.

Regulatory roles of non-coding RNAs and m6A modification in trophoblast functions and the occurrence of its related adverse pregnancy outcomes

Adverse pregnancy outcomes, such as preeclampsia, gestational diabetes mellitus, fetal growth restriction, and recurrent miscarriage, occur frequently in pregnant women and might further induce morbidity and mortality for both mother and fetus. Increasing studies have shown that dysfunctions of human trophoblast are related to these adverse pregnancy outcomes. Recent studies also showed that environmental toxicants could induce trophoblast dysfunctions. Moreover, non-coding RNAs (ncRNAs) have been reported to play important regulatory roles in various cellular processes. However, the roles of ncRNAs in the regulation of trophoblast dysfunctions and the occurrence of adverse pregnancy outcomes still need to be further investigated, especially with exposure to environmental toxicants. In this review, we analyzed the regulatory mechanisms of ncRNAs and m6A methylation modification in the dysfunctions of trophoblast cells and the occurrence of adverse pregnancy outcomes and also summarized the harmful effects of environmental toxicants. In addition to DNA replication, mRNA transcription, and protein translation, ncRNAs and m6A modification might be considered as the fourth and fifth elements that regulate the genetic central dogma, respectively. Environmental toxicants might also affect these processes. In this review, we expect to provide a deeper scientific understanding of the occurrence of adverse pregnancy outcomes and to discover potential biomarkers for the diagnosis and treatment of these outcomes.

Epidermal growth factor induces a trophectoderm lineage transcriptome resembling that of human embryos during reconstruction of blastoids from extended pluripotent stem cells

Objectives

This study aims to optimize the human extended pluripotent stem cell (EPSC) to trophectoderm (TE)‐like cell induction with addition of EGF and improve the quality of the reconstructing blastoids.

Materials and Methods

TE‐like cells were differentiated from human EPSCs. RNA‐seq data analysis was performed to compare with TE‐like cells from multiple human pluripotent stem cells (hPSCs) and embryos. A small‐scale compound selection was performed for optimizing the TE‐like cell induction and the efficiency was characterized using TE‐lineage markers expression by immunofluorescence stanning. Blastoids were generated by using the optimized TE‐like cells and the undifferentiated human EPSCs through three‐dimensional culture system. Single‐cell RNA sequencing was performed to investigate the lineage segregation of the optimized blastoids to human blastocysts.

Results

TE‐like cells derived from human EPSCs exhibited similar transcriptome with TE cells from embryos. Additionally, TE‐like cells from multiple naive hPSCs exhibited heterogeneous gene expression patterns and signalling pathways because of the incomplete silencing of naive‐specific genes and loss of imprinting. Furthermore, with the addition of EGF, TE‐like cells derived from human EPSCs enhanced the TE lineage‐related signalling pathways and exhibited more similar transcriptome to human embryos. Through resembling with undifferentiated human EPSCs, we elevated the quality and efficiency of reconstructing blastoids and separated more lineage cells with precise temporal and spatial expression, especially the PE lineage.

Conclusion

Addition of EGF enhanced TE lineage differentiation and human blastoids reconstruction. The optimized blastoids could be used as a blastocyst model for simulating early embryonic development.

Early human trophoblast development: from morphology to function

Human pregnancy depends on the proper development of the embryo prior to implantation and the implantation of the embryo into the uterine wall. During the pre-implantation phase, formation of the morula is followed by internalization of blastomeres that differentiate into the pluripotent inner cell mass lineage, while the cells on the surface undergo polarization and differentiate into the trophectoderm of the blastocyst. The trophectoderm mediates apposition and adhesion of the blastocyst to the uterine epithelium. These processes lead to a stable contact between embryonic and maternal tissues, resulting in the formation of a new organ, the placenta. During implantation, the trophectoderm cells start to differentiate and form the basis for multiple specialized trophoblast subpopulations, all of which fulfilling specific key functions in placentation. They either differentiate into polar cells serving typical epithelial functions, or into apolar invasive cells that adapt the uterine wall to progressing pregnancy. The composition of these trophoblast subpopulations is crucial for human placenta development and alterations are suggested to result in placenta-associated pregnancy pathologies. This review article focuses on what is known about very early processes in human reproduction and emphasizes on morphological and functional aspects of early trophoblast differentiation and subpopulations.

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.

In Vitro Model of Human Trophoblast in Early Placentation

The complex process of placental implantation and development affects trophoblast progenitors and uterine cells through the regulation of transcription factors, cytokines, adhesion receptors and their ligands. Differentiation of trophoblast precursors in the trophectoderm of early ontogenesis, caused by the transcription factors, such as CDX2, TEAD4, Eomes and GATA3, leads to the formation of cytotrophoblast and syncytiotrophoblast populations. The molecular mechanisms involved in placental formation inside the human body along with the specification and differentiation of trophoblast cell lines are, mostly due to the lack of suitable cell models, not sufficiently elucidated. This review is an evaluation of current technologies, which are used to study the behavior of human trophoblasts and other placental cells, as well as their ability to represent physiological conditions both in vivo and in vitro. An in vitro 3D model with a characteristic phenotype is of great benefit for the study of placental physiology. At the same time, it provides great support for future modeling of placental disease.

MicroRNA-495 suppresses pre-eclampsia via activation of p53/PUMA axis

Linkage between microRNAs (miRNAs) and pre-eclampsia (PE) has been documented. Here, we focused on miR-495 in PE and its underlying mechanism in regulation of trophoblast cells. Expression of miR-495, HDAC2, p53 and PUMA was determined in collected placental tissue samples. Loss- and gain-function was performed to determine the roles of miR-495, HDAC2, p53, and PUMA in biological processes of HTR8/SVneo cells and primary trophoblast cells. The relationships among miR-495, HDAC2, and p53 were pinpointed. PE patients presented with higher expression of miR-495, p53, and PUMA in placental tissues, but lower HDAC2. miR-495 negatively targeted HDAC2 expression. HDAC2 suppressed p53 expression via deacetylation. Overexpression of miR-495, p53, or PUMA inhibited biological properties of HTR8/SVneo cells and primary trophoblast cells, while opposite trends were observed in response to oe-HDAC2. In conclusion, miR-495 knockdown can suppress p53/PUMA axis by targeting HDAC2 to enhance biological behaviors of trophoblast cells, which may prevent occurrence of PE.

ANKRD37 inhibits trophoblast migration and invasion by regulating NF-κB pathway in preeclampsia

BACKGROUND

Inadequate trophoblast invasion is associated with preeclampsia (PE). Ankyrin repeat domain protein 37 (ANKRD37) has been reported to be abnormally expressed in PE placentas. However, the role of ANKRD37 in trophoblasts has not been investigated. We aimed to determine the functions of ANKRD37 in PE and to explore the molecular mechanisms.

METHODS

Here, fluorescence in situ hybridization, immunohistochemistry, Western blotting and quantitative real-time PCR were used to detect protein and mRNA expression levels. Cell Counting Kit-8 (CCK-8), EdU assay, flow cytometry, wound healing assay, Transwell assay and RNA sequencing were performed to study the role of ANKRD37 and the underlying mechanism in HTR8/SVneo and JEG-3 cells, and extravillous explant cultures were used to evaluate the migration and invasion abilities of extravillous cytotrophoblasts (EVTs).

RESULTS

We found that ANKRD37 expression was upregulated in PE placentas compared to normal pregnancy placentas. ANKRD37 knockdown enhanced trophoblast migration and invasion, promoted extravillous explant outgrowth, and regulated the expression of key invasion proteins, while ANKRD37 overexpression exerted the opposite effects. RNA sequencing indicated that NF-κB was the potential downstream pathway of ANKRD37, which was confirmed by the change in p-p65 and p-IκBα expression in JEG-3 and HTR8/SVneo cells.

CONCLUSIONS

Our findings suggest that high expression of ANKRD37 inhibits trophoblast cell migration and invasion possibly via NF-κB pathway, and may be related to the development of PE.

A novel regulatory mechanism network mediated by lncRNA TUG1 that induces the impairment of spiral artery remodeling in Preeclampsia

Preeclampsia (PE) is associated with maternal and fetal perinatal morbidity and mortality, which brings tremendous suffering and imposes an economic burden worldwide. The failure of uterine spiral artery remodeling may be related to the abnormal function of trophoblasts and lead to the occurrence and progression of PE. Aberrant expression of long non-coding RNAs (lncRNAs) is involved in the failure of uterine spiral artery remodeling. However, the regulation of lncRNA expression in PE is poorly characterized. Here, we reported that hypoxia-induced microRNA (miR)-218 inhibited the expression of lncRNA TUG1 by targeting FOXP1. Further RNA sequencing and mechanism analysis revealed that silencing of TUG1 increased the expression of DNA demethylase TET3 and proliferation-related DUSP family, including DUSP2, DUSP4, and DUSP5, via binding to SUV39H1 in the nucleus. Moreover, TUG1 modulated the DUSP family in vitro through a TET3-mediated epigenetic mechanism. Taken together, our results unmask a new regulatory network mediated by TUG1 as an essential determinant of the pathogenesis of PE, which regulates cell growth and possibly the occurrence and development of other diseases.

Preeclamptic Women Have Disrupted Placental microRNA Expression at the Time of Preeclampsia Diagnosis: Meta-Analysis

Introduction: Preeclampsia (PE) is a pregnancy-associated, multi-organ, life-threatening disease that appears after the 20th week of gestation. The aim of this study was to perform a systematic review and meta-analysis to determine whether women with PE have disrupted miRNA expression compared to women who do not have PE. Methods: We conducted a systematic review and meta-analysis of studies that reported miRNAs expression levels in placenta or peripheral blood of pregnant women with vs. without PE. Studies published before October 29, 2021 were identified through PubMed, EMBASE and Web of Science. Two reviewers used predefined forms and protocols to evaluate independently the eligibility of studies based on titles and abstracts and to perform full-text screening, data abstraction and quality assessment. Standardized mean difference (SMD) was used as a measure of effect size. Results: 229 publications were included in the systematic review and 53 in the meta-analysis. The expression levels in placenta were significantly higher in women with PE compared to women without PE for miRNA-16 (SMD = 1.51,95%CI = 0.55-2.46), miRNA-20b (SMD = 0.89, 95%CI = 0.33-1.45), miRNA-23a (SMD = 2.02, 95%CI = 1.25-2.78), miRNA-29b (SMD = 1.37, 95%CI = 0.36-2.37), miRNA-155 (SMD = 2.99, 95%CI = 0.83-5.14) and miRNA-210 (SMD = 1.63, 95%CI = 0.69-2.58), and significantly lower for miRNA-376c (SMD = -4.86, 95%CI = -9.51 to -0.20). An increased level of miRNK-155 expression was found in peripheral blood of women with PE (SMD = 2.06, 95%CI = 0.35-3.76), while the expression level of miRNA-16 was significantly lower in peripheral blood of PE women (SMD = -0.47, 95%CI = -0.91 to -0.03). The functional roles of the presented miRNAs include control of trophoblast proliferation, migration, invasion, apoptosis, differentiation, cellular metabolism and angiogenesis. Conclusion: miRNAs play an important role in the pathophysiology of PE. The identification of differentially expressed miRNAs in maternal blood creates an opportunity to define an easily accessible biomarker of PE.

A Novel Circular RNA CircBRAP May Be Used as an Early Predictor of Preeclampsia and Its Potential Mechanism

Preeclampsia (PE), a pregnancy-related multisystem syndrome, is one of the leading causes of maternal and fetal mortality worldwide. The aim of this study was to combine the plasma protein soluble Fms-related tyrosine kinase 1 (sFLT1) levels with uterine artery Doppler ultrasound findings and CircBRAP levels during the first trimester to predict the occurrence of preeclampsia and to explore the potential mechanism by which CircBRAP functions in preeclampsia. Here, we used qRT-PCR to investigate the expression of CircBRAP in forty-nine pairs of plasma specimens and placental tissues from preeclampsia patients and control subjects. The uterine artery (UtA) pulsatility index (PI) was measured using four-dimensional color Doppler ultrasound, and the sFLT1 levels were evaluated by human immunoassay. Exogenous upregulation or downregulation of CircBRAP expression in TEV-1 trophoblast cells was performed to investigate the role of CircBRAP in cell biological behavior. Mechanistically, luciferase reporter, RNA immunoprecipitation (RIP), and biotin-coupled RNA pull-down assays were conducted to verify the relationship between CircBRAP and sFLT1 in TEV-1 cells. The results showed that the predictive power was strengthened when the plasma sFLT1 and CircBRAP levels were combined with the UtA-PI to predict preeclampsia occurrence. Our study also revealed that CircBRAP may regulate miR-106b and the HIF-2α axis to modulate the proliferation, invasion, and apoptosis of TEV-1 trophoblast cells. In summary, placenta-derived CircBRAP in plasma may be a novel biomarker for preeclampsia that, together with plasma sFLT1 levels and uterine artery Doppler ultrasound findings, can more effectively predict preeclampsia, and CircBRAP may play a potential role in preeclampsia.

miR-218-5p Induces Interleukin-1β and Endovascular Trophoblast Differentiation by Targeting the Transforming Growth Factor β-SMAD2 Pathway

The acquisition of an endovascular trophoblast (enEVT) phenotype is essential for normal placental development and healthy pregnancy. MicroRNAs (miRNAs) are small noncoding RNAs that play critical roles in regulating gene expression. We have recently reported that miR-218-5p promotes enEVT differentiation and spiral artery remodeling in part by targeting transforming growth factor β2 (TGFβ2). We also identified IL1B, which encodes interleukin 1β (IL1β), as one of the most highly upregulated genes by miR-218-5p. In this study, we investigated how miR-218-5p regulates IL1B expression and IL1β secretion and the potential role of IL1β in enEVT differentiation. Using two cell lines derived from extravillous trophoblasts (EVTs), HTR-8/SVneo and Swan 71, we found that stable overexpression of miR-218-5p precursor, mir-218-1, or transient transfection of miR-218-5p mimic, significantly increased IL1B mRNA and IL1β protein levels in cells and conditioned media. We also showed that miR-218-5p directly interacted with SMAD2 3'UTR and reduced SMAD2 at mRNA and protein levels. Knockdown of SMAD2 induced IL1B expression and attenuated the inhibitory effect of TGFβ2 on IL1B expression. On the other hand, overexpression of SMAD2 reduced IL1β levels and blocked the stimulatory effects of miR-218-5p on IL1B expression, trophoblast migration and endothelial-like network formation. In addition, treatment of trophoblasts with IL1β induced the formation of endothelial-like networks and the expression of enEVT markers in a dose-dependent manner. These results suggest that miR-218-5p inhibits the TGFβ/SMAD2 pathway to induce IL1β and enEVT differentiation. Finally, low doses of IL1β also inhibited the expression of miR-218-5p, suggesting the existence of a negative feedback regulatory loop. Taken together, our findings suggest a novel interactive miR-218-5p/TGFβ/SMAD2/IL1β signaling nexus that regulates enEVT differentiation.

Magnesium sulfate reduces vascular endothelial cell apoptosis in rats with preeclampsia via the miR-218-5p/HMGB1 pathway

OBJECTIVE

This study aims to investigate the mechanism by which magnesium sulfate regulates the miR-218-5p/HMGB-pathway-mediated apoptosis of vascular endothelial cells (VECs) in rats with preeclampsia (PE).

METHODS

Twenty pregnant rats were randomly divided into four groups: normal, PE, MgSO₄, and high-mobility group protein B1 (HMGB1)-agomir groups. On the 14^th day of each rat's pregnancy, endotoxin was used to establish a PE model in the PE, MgSO₄, and HMGB1-agomir groups. Then, the MgSO₄ and HMGB1-agomir groups were treated with magnesium sulfate. Finally, HMGB1 overexpression was performed only in the HMGB1-agomir group. The rats' urinary protein content and systolic blood pressure at 24 h were detected on the 11^th, 13^th, 15^th, 17^th, and 19^th day of pregnancy.

RESULTS

Compared with the PE group, 24-h urinary protein content, blood pressure, VEC apoptosis rate, apoptosis marker levels, and HMGB1 expression decreased while miR-218-5p levels increased in the MgSO₄ group. The dual-luciferase assay revealed that HMGB1 can be targeted and regulated by miR-218-5p. Compared with the MgSO₄ group, 24-h urinary protein content, blood pressure, VEC apoptosis rate, apoptosis marker levels, and HMGB1 expression increased while miR-218-5p levels decreased in the HMGB1-agomir group.

CONCLUSION

MgSO₄ reduces VEC apoptosis in PE rats via the miR-218-5p/HMGB1 pathway and thus plays a role in treating PE.

HLA-G: An Important Mediator of Maternal-Fetal Immune-Tolerance

Maternal-fetal immune-tolerance occurs throughout the whole gestational trimester, thus a mother can accept a genetically distinct fetus without immunological aggressive behavior. HLA-G, one of the non-classical HLA class I molecules, is restricted-expression at extravillous trophoblast. It can concordantly interact with various kinds of receptors mounted on maternally immune cells residing in the uterus (e.g. CD4+ T cells, CD8+ T cells, natural killer cells, macrophages, and dendritic cells) for maintaining immune homeostasis of the maternal-fetus interface. HLA-G is widely regarded as the pivotal protective factor for successful pregnancies. In the past 20 years, researches associated with HLA-G have been continually published. Indeed, HLA-G plays a mysterious role in the mechanism of maternal-fetal immune-tolerance. It can also be ectopically expressed on tumor cells, infected sites and other pathologic microenvironments to confer a significant local tolerance. Understanding the characteristics of HLA-G in immunologic tolerance is not only beneficial for pathological pregnancy, but also helpful to the therapy of other immune-related diseases, such as organ transplant rejection, tumor migration, and autoimmune disease. In this review, we describe the biological properties of HLA-G, then summarize our understanding of the mechanisms of fetomaternal immunologic tolerance and the difference from transplant tolerance. Furthermore, we will discuss how HLA-G contributes to the tolerogenic microenvironment during pregnancy. Finally, we hope to find some new aspects of HLA-G in fundamental research or clinical application for the future.

miR-519d downregulates LEP expression to inhibit preeclampsia development

The purpose of the current study was to characterize role of microRNA (miR)-519d in trophoblast cells and preeclampsia (PE) development and its potential underlying mechanism. Regulation of leptin (LEP) by miR-519d was verified using a dual-luciferase reporter gene assay. Loss- and gain-of-function assays were conducted to detect the roles of miR-519d and LEP in proliferation, migratory ability, and invasive capacity of HTR-8/SVneo cells by means of CCK-8 assay, scratch test, and Transwell invasion assay, respectively. The cell apoptosis rate and cycle distribution were analyzed by flow cytometry. LEP expression was elevated, whereas miR-519d level was suppressed in the PE placenta samples compared with those from normal pregnancy. Depletion of LEP promoted proliferation, migratory ability, and invasive capacity and repressed apoptosis. miR-519d could bind 3' untranslated regions (3'UTRs) of LEP, the extent of which correlated negatively with LEP expression. miR-519d suppressed the expression of LEP in HTR-8/SVneo cells. Moreover, overexpression of miR-519d promoted survival and migratory ability of HTR-8/SVneo cells. Taken together, we find that miR-519d targeted LEP and downregulated its expression, which could likely inhibit the development of PE.

miR-146a-5p-mediated suppression on trophoblast cell progression and epithelial-mesenchymal transition in preeclampsia

Objective

This study aims to identify the effect of miR-146a-5p on trophoblast cell invasion as well as the mechanism in preeclampsia (PE).

Methods

Expression levels of miR-146a-5p and Wnt2 in preeclamptic and normal placentae were quantified. Trophoblast cells (HTR-8) were separately transfected with miR-146a-5p mimic, miR-146a-5p inhibitor, pcDNA3.1-Wnt2 or sh-Wnt2, and then the expression levels of miR-146a-5p, Wnt2, and epithelial-mesenchymal transition (EMT)-related proteins (Vimentin, N-cadherin and E-cadherin) were measured. Moreover, the proliferative, migratory and invasive capacities of trophoblast cells were detected, respectively. Dual luciferase reporter assay determined the binding of miR-146a-5p and Wnt2.

Results

Compared with normal placental tissues, the placentae from PE patients showed higher miR-146a-5p expression and lower Wnt2 expression. Transfection of miR-146a-5p inhibitor or pcDNA3.1-Wnt2 exerted pro-migratory and pro-invasive effects on HTR-8 cells and encouraged EMT in HTR-8 cells; transfection with miR-146a-5p mimic or sh-Wnt2 weakened the proliferative, migratory and invasive capacities as well as reduced EMT process of HTR-8 cells. Moreover, Wnt2 overexpression could partially counteract the suppressive effects of miR-146a-5p overexpression on the progression and EMT of HTR-8 cells.

Conclusion

miR-146a-5p mediates trophoblast cell proliferation and invasion through regulating Wnt2 expression.

Integrative analysis of miRNA-mRNA expression profiles in esophageal fibrosis after ESD

The incidence of esophageal fibrosis and benign esophageal stricture (BES) has increased in recent years due to the curative therapy for early-stage esophageal carcinoma, including partial esophagectomy and esophageal endoscopic submucosal dissection (ESD). The aim of the present study was to identify key genes and associated pathways of esophageal fibrosis after the ESD procedure. During the esophageal ESD procedure, the esophageal tissue in the remaining submucosal layer, referred to as normal esophageal (NE) tissue, was collected, and 1 week thereafter, post-operative esophageal (PE) tissue was obtained. High-throughput sequencing was used to identify dysregulated microRNAs (miRNAs/miRs) between NE and PE tissues. According to the differentially expressed (DE) miRNAs, putative target genes were predicted. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes enrichment analysis and DEmiRNA interaction network analysis were performed. Reverse transcription-quantitative PCR (RT-qPCR) was performed to validate the RNA-sequencing results. A total of 199 miRNAs were determined to be DE between NE and PE tissues. Compared with the expression in the NE group, 83 miRNAs were significantly upregulated, while 116 miRNAs were significantly downregulated. According to these DE miRNAs, forkhead box O1 (FOXO1), paired box 6 (PAX6), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and adrenoceptor β1 (ADRB1) were DE genes regulated by five DE miRNAs, including miR-223-3p, miR-142-5p, miR-582-5p, miR-21-3p and miR-218-5p. The results suggested that certain pathways were markedly dysregulated, including FOXO, MAPK, AMP-activated protein kinase and signaling pathways regulating the pluripotency of stem cells and proteoglycans in cancer. According to the RT-qPCR results, the expression levels of FOXO1, PAX6, ADRB1, miR-223-3p, miR-582-5p, miR-21-3p and miR-218-5p were consistent with the integrated analysis. In conclusion, FOXO1, PAX6, PIK3CA and ADRB1 may have a role in esophageal fibrosis, regulated by miR-223-3p, miR-142-5p, miR-582-5p, miR-21-3p and miR-218-5p. The present results provided an improved understanding of the changes in the microenvironment during the process of esophageal fibrosis, as well as novel potential targets for the treatment of esophageal fibrosis and BES.

LncRNA LINC01088 inhibits the function of trophoblast cells, activates the MAPK-signaling pathway and associates with recurrent pregnancy loss

Long noncoding RNAs (lncRNAs) have been reported to be involved in various cellular processes and to participate in a variety of human diseases. Recently, increasing studies have reported that lncRNAs are related to many reproductive diseases, such as pathogenesis of recurrent pregnancy loss (RPL), preeclampsia (PE) and gestational diabetes mellitus (GDM). In this study, we aimed to investigate the effect of LINC01088 in trophoblast cells and its potential role in pathogenesis of RPL. LINC01088 was found to be upregulated in first-trimester chorionic villi tissues from RPL patients. Increased LINC01088 repressed proliferation, migration and invasion of trophoblast cells, and promoted apoptosis of trophoblast cells. Further exploration indicated that LINC01088 decreased the production of nitric oxide (NO) by binding and increasing Arginase-1 and decreasing eNOS protein levels. Importantly, JNK and p38 MAPK-signaling pathways were active after overexpression of LINC01088. In conclusion, our studies demonstrated that LINC01088 plays an important role in the pathogenesis of RPL, and is a potential therapeutic target for the treatment of RPL.

Overexpression of let-7d explains down-regulated KDM3A and ENO2 in the pathogenesis of preeclampsia

Pre‐eclampsia (PE) is the leading cause of maternal death; however, the causative molecular basis remains largely unknown. Recent studies have revealed the important role microRNAs (miRNAs) play in PE. We aimed to explore the effects of let‐7d on trophoblast proliferation, migration, invasion and apoptosis in PE and its underlying mechanism. Placental tissues were collected from PE patients and healthy pregnant women, and it was found that let‐7d expression was increased, while KDM3A and ENO2 expression was decreased in PE tissues and cells. Bioinformatics analysis indicated the interaction among let‐7d, KDM3A and ENO2, confirmed by dual luciferase reporter gene assay; ChIP experiment identified methylated modification to ENO2 by KDM3A. With gain‐ and loss‐function method, silencing of let‐7d increased KDM3A expression and enhanced the binding between KDM3A and ENO2. Furthermore, overexpression of let‐7d suppressed cell proliferation, migration and invasion of trophoblasts, and induced apoptosis of trophoblasts, while these capacities were restored upon additional treatment of overexpressed ENO2. PE rat models were established to explore the effects of let‐7d and ENO2 on PE in vivo. The results established that the silencing of let‐7d alleviated the tissue injury and PE‐related symptoms when reducing urine protein, TUNEL‐positive cells and increasing ENO2, and KDM3A expression in rats. Cumulatively, let‐7d suppressed cell progression of trophoblasts, and induced apoptosis through the down‐regulation of KDM3A to promote ENO2 methylation, thereby promoting progression of PE. Such an epigenetic network of let‐7d, KDM3A and ENO2 in the pathogenesis of PE might provide novel insight into targeted therapy against this disorder.

Roles of noncoding RNAs in preeclampsia

Preeclampsia (PE) is an idiopathic disease that occurs during pregnancy. It comprises multiple organ and system damage, and can seriously threaten the safety of the mother and infant throughout the perinatal period. As the pathogenesis of PE is unclear, there are few specific remedies. Currently, the only way to eliminate the clinical symptoms is to terminate the pregnancy. Although noncoding RNA (ncRNA) was once thought to be the "junk" of gene transcription, it is now known to be widely involved in pathological and physiological processes, including pregnancy-related disorders. Moreover, there is growing evidence that the unbalanced expression of specific ncRNA is involved in the pathogenesis of PE. In the present review, we summarize the expression patterns of ncRNAs, i.e., microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), and the functional mechanisms by which they affect the development of PE, and examine the clinical significance of ncRNAs as biomarkers for the diagnosis of PE. We also discuss the contributions made by genetic polymorphisms and epigenetic ncRNA regulation to PE. In the present review, we wish to explore and reinforce the clinical value of ncRNAs as noninvasive biomarkers of PE.

Regulation of placentation by the transforming growth factor beta superfamily†

During pregnancy, there is increased expression of some cytokines at the fetal-maternal interface; and the clarification of their roles in trophoblast-endometrium interactions is crucial to understanding the mechanism of placentation. This review addresses the up-to-date reported mechanisms by which the members of the transforming growth factor beta superfamily regulate trophoblast proliferation, differentiation, and invasion of the decidua, which are the main phases of placentation. The available information shows that these cytokines regulate placentation in somehow a synergistic and an antagonistic manner; and that dysregulation of their levels can lead to aberrant placentation. Nevertheless, prospective studies are needed to reconcile some conflicting reports; and identify some unknown mediators involved in the actions of these cytokines before their detailed mechanistic regulation of human placentation could be fully characterized. The TGF beta superfamily are expressed in the placenta, and regulate the process of placentation through the activation of several signaling pathways.

Recent Advances of MicroRNAs, Long Non-coding RNAs, and Circular RNAs in Preeclampsia

Preeclampsia is a clinical syndrome characterized by multiple-organ dysfunction, such as maternal hypertension and proteinuria, after 20 weeks of gestation. It is a common cause of fetal growth restriction, fetal malformation, and maternal death. At present, termination of pregnancy is the only way to prevent the development of the disease. Non-coding RNAs, including microRNAs, long non-coding RNAs, and circular RNAs, are involved in important pathological and physiological functions in life cycle activities including ontogeny, reproduction, apoptosis, and cell reprogramming, and are closely associated with human diseases. Accumulating evidence suggests that non-coding RNAs are involved in the pathogenesis of preeclampsia through regulation of various physiological functions. In this review, we discuss the current evidence of the pathogenesis of preeclampsia, introduce the types and biological functions of non-coding RNA, and summarize the roles of non-coding RNA in the pathophysiological development of preeclampsia from the perspectives of oxidative stress, hypoxia, angiogenesis, decidualization, trophoblast invasion and proliferation, immune regulation, and inflammation. Finally, we briefly discuss the potential clinical application and future prospects of non-coding RNA as a biomarker for the diagnosis of preeclampsia.

Pigment epithelium-derived factor, a novel decidual natural killer cells-derived factor, protects decidual stromal cells via anti-inflammation and anti-apoptosis in early pregnancy

STUDY QUESTION

What is the role of pigment epithelium-derived factor (PEDF) from decidual natural killer (dNK) cells during early pregnancy?

SUMMARY ANSWER

PEDF from dNK cells limits the lipopolysaccharide (LPS)-induced apoptosis and inflammation of decidual stromal cells (DSCs) to maintain DSCs homoeostasis and immune balance at the maternal-foetal interface during early pregnancy.

WHAT IS KNOWN ALREADY

dNK cells, which secrete PEDF, play critical roles during pregnancy via a series of key regulators. PEDF, a multifunctional endogenous glycoprotein, exhibits a wide range of biological actions upon angiogenesis, inflammation, metabolic homoeostasis, immunomodulation etc., providing potential clinical applications.

STUDY DESIGN, SIZE, DURATION

Natural killer (NK) cells from decidua and peripheral blood as well as DSCs isolated from normal pregnancy (NP) during the first trimester (6-10 weeks) and the matched patients suffering recurrent miscarriage (RM) were studied. RNA-sequencing analysis of dNK cells was performed to screen for potential key genes involved in RM. The expression of PEDF in dNK cells in NP and RM was examined. A coculture system with LPS-stimulated DSCs and NK cell supernatants derived from NP or RM was established to explore the regulatory mechanisms of PEDF at the maternal-foetal interface.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Peripheral blood and decidual tissues were obtained from women with NP (n = 61) and RM (n = 21). The expression levels of PEDF in NK cells and its receptor (PEDFR) on DSCs were analysed using flow cytometry, western blot and immunohistochemistry. Purified peripheral natural killer (pNK) cells were cocultured with DSCs or trophoblast cells or a combination of both cell types, and PEDF expression in pNK cells was then examined by flow cytometry. DSCs were treated with LPS, an outer-membrane component of Gram-negative bacteria, thereby mimicking an enhanced inflammatory status within decidua, and were cocultured with dNK cell supernatants from NP or RM. In the coculture system, plasmids expressing short hairpin RNA were used to silence PEDFR on DSCs and block the PEDF/PEDFR interaction. Inflammatory cytokines and apoptosis of DSCs treated as described above were assessed by flow cytometry. Western blotting was performed, and the specific signal pathway inhibitors were used to determine downstream PEDF/PEDFR signalling in early decidua.

MAIN RESULTS AND THE ROLE OF CHANCE

Markedly higher RNA (P < 0.001) and protein expression of PEDF (P < 0.01) was detected in normal dNK cells when compared with pNK cells. Compared with pNK cells cultured alone, PEDF expression in pNK cells was elevated after coculture with DSCs (P < 0.01) or trophoblast cells (P < 0.001). The increased pro-inflammatory cytokine, tumour necrosis factor-α and apoptosis of DSCs following LPS stimulation were suppressed by recombinant human PEDF (P < 0.001) or the supernatant of dNK cells derived from NP (P < 0.001). However, these effects were somewhat abrogated when the PEDF/PEDFR interaction was blocked with PEDFR short hairpin sRNA (P < 0.01). Furthermore, dNK cell-derived PEDF protected DSCs from LPS-induced inflammation via inhibition of nuclear factor kappa-B activation, while also protecting DSCs from LPS-induced apoptosis via promotion of extracellular signal-regulated kinase expression. Compared with NP, both significantly decreased PEDF RNA (P < 0.001) and protein expression (P < 0.001) in dNK cells, but not in pNK cells (P > 0.05), were detected in women with RM. PEDFR on DSCs was also decreased within RM compared with that within NP (P < 0.001). As a result, dNK cell-mediated anti-inflammation (P < 0.01) and anti-apoptosis (P < 0.05) for protection of LPS-treated DSCs was attenuated in patients suffering from RM.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

We cannot exclude the possibility that the differences in amounts of PEDF and its receptor in tissue from NP versus RM women could be caused by the miscarriage event in women with RM. Our experiments only involved human samples investigated in vitro. Experiments in animal models and human study cohorts are still needed to confirm these findings and further clarify the role of PEDF-PEDFR in NP and/or RM.

WIDER IMPLICATIONS OF THE FINDINGS

To the best of our knowledge, this is the first study to demonstrate PEDF expression and function at the maternal-foetal interface in the first trimester, providing further evidence that PEDF exhibits functional diversity and has great potential for clinical application(s). The findings of selectively high expression of PEDF in normal dNK cells and the PEDF-mediated role of dNK cells during NP and RM help to further elucidate the immune mechanisms behind RM.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Basic Research Programme of China (2017YFC1001403 and 2015CB943300), Nature Science Foundation from National Nature Science Foundation of China (NSFC; 31970859, 81630036, 81501334, 91542116, 31570920, 81490744 and 31171437), the Innovation-oriented Science and Technology Grant from NHC Key Laboratory of Reproduction Regulation (CX2017-2), the Programme of Shanghai Academic/Technology Research Leader (17XD1400900) and the Key Project of Shanghai Basic Research from Shanghai Municipal Science and Technology Commission (STCSM; 12JC1401600). None of the authors has any conflict of interest to declare.

Downregulation of fascin in the first trimester placental villi is associated with early recurrent miscarriage

Inadequate trophoblast proliferation, shallow invasion and exaggerated rate of trophoblast apoptosis are implicated in early recurrent miscarriage (ERM). However, the mechanistic bases of this association have not been fully established. We aimed at investigating the involvement of fascin, an actin-bundling protein, in trophoblast activities and ERM. We found that fascin was downregulated in the cytotrophoblasts (CTBs) and distal cytotrophoblasts (DCTs) of ERM placentae. Knockdown of fascin altered cellular and nucleolar morphology, and inhibited the proliferation but increased apoptosis of trophoblastic HTR8/SVneo cells. Furthermore, fascin knockdown decreased the expression of transcription factors such as Snail1/2, Twist and Zeb1/2, mesenchymal molecules such as Vimentin and N-cadherin, and the protein expression of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphorylates signal transducer and activator of transcript 3 (STAT3). Exposure of HTR-8/SVneo cells to hypoxia reoxygenation (H/R) decreased fascin expression to affect the cells' invasion. Our results indicate for the first time that the downregulation of fascin is involved in the pathogenesis of early recurrent miscarriage; and hence a potential therapeutic target against the disease.

Overexpression of miR-210-3p Impairs Extravillous Trophoblast Functions Associated with Uterine Spiral Artery Remodeling

Hsa-miR-210-3p has been reported to be upregulated in preeclampsia (PE); however, the functions of miR-210-3p in placental development are not fully understood, and, consequently, miR-210-3p’s role in the pathogenesis of PE is still under investigation. In this study, we found that overexpression of miR-210-3p reduced trophoblast migration and invasion, extravillous trophoblast (EVT) outgrowth in first trimester explants, expression of endovascular trophoblast (enEVT) markers and the ability of trophoblast to form endothelial-like networks. In addition, miR-210-3p overexpression significantly downregulated the mRNA levels of interleukin-1B and -8, as well as CXC motif ligand 1. These cytokines have been suggested to play a role in EVT invasion and the recruitment of immune cells to the spiral artery remodeling sites. We also showed that caudal-related homeobox transcription factor 2 (CDX2) is targeted by miR-210-3p and that CDX2 downregulation mimicked the observed effects of miR-210-3p upregulation in trophoblasts. These findings suggest that miR-210-3p may play a role in regulating events associated with enEVT functions and its overexpression could impair spiral artery remodeling, thereby contributing to PE.

Regulation of endothelial cell differentiation in embryonic vascular development and its therapeutic potential in cardiovascular diseases

During vertebrate development, the cardiovascular system begins operating earlier than any other organ in the embryo. Endothelial cell (EC) forms the inner lining of blood vessels, and its extensive proliferation and migration are requisite for vasculogenesis and angiogenesis. Many aspects of cellular biology are involved in vasculogenesis and angiogenesis, including the tip versus stalk cell specification. Recently, epigenetics has attracted growing attention in regulating embryonic vascular development and controlling EC differentiation. Some proteins that regulate chromatin structure have been shown to be directly implicated in human cardiovascular diseases. Additionally, the roles of important EC signaling such as vascular endothelial growth factor and its receptors, angiopoietin-1 and tyrosine kinase containing immunoglobulin and epidermal growth factor homology domain-2, and transforming growth factor-β in EC differentiation during embryonic vasculature development are briefly discussed in this review. Recently, the transplantation of human induced pluripotent stem cell (iPSC)-ECs are promising approaches for the treatment of ischemic cardiovascular disease including myocardial infarction. Patient-specific iPSC-derived EC is a potential new target to study differences in gene expression or response to drugs. However, clinical application of the iPSC-ECs in regenerative medicine is often limited by the challenges of maintaining cell viability and function. Therefore, novel insights into the molecular mechanisms underlying EC differentiation might provide a better understanding of embryonic vascular development and bring out more effective EC-based therapeutic strategies for cardiovascular diseases.

Insight into the Key Points of Preeclampsia Pathophysiology: Uterine Artery Remodeling and the Role of MicroRNAs

Preeclampsia affects about 3-8% of all pregnancies. It represents a complex and multifaceted syndrome with at least several potential pathways leading to the development of disease. The main dogma in preeclampsia is the two-stage model of disease. Stage 1 (placental stage) takes place in early pregnancy and is thought to be impaired placentation due to inadequate trophoblastic invasion of the maternal spiral arteries that leads to reduced placental perfusion and release of numerous biological factors causing endothelial damage and development of acute maternal syndrome with systemic multiorgan failure (stage 2-the onset of maternal clinical symptoms, maternal stage). Recently, in the light of the vast body of evidence, two-stage model of preeclampsia has been updated with a few novel pathways leading to clinical manifestation in the second part of pregnancy. This paper reviews current state of knowledge about pathophysiology of preeclampsia and places particular focus on the recent advances in understanding of uterine artery remodeling alterations, as well as the role of microRNAs in preeclampsia.

Multiplexed and single-cell detection of microRNA with plasmonic nanoparticle assemblies

We present a label-free, low cost, and miniatured biosensing platform based on the disassembly of core-satellite plasmonic nanoparticle assemblies. The rapid and selective detection of an exemplary nucleic acid biomarker, has-miRNA-210-3p, was achieved via the strand displacement nucleic acid reaction. Target binding leads to dehybridization of the DNA linkers and changes in the scattering properties of nanostructures as monitored by darkfield microscopy. We demonstrate the ability to detect microRNA expunged from single cells and the potential to multiplex discrete assemblies to enable diverse biological applicability. The work may help translate the applicability of microRNA as diagnostic biomarkers, quantitate their abundance in the microenvironment, and facilitate the study of their correlation or causation to other biomolecules at the single-cell level.

Upregulation of miR-29a suppressed the migration and invasion of trophoblasts by directly targeting LOXL2 in preeclampsia

OBJECTIVE

Preeclampsia is a pregnancy-specific disorder that is a major cause of maternal and foetal morbidity and mortality, with a prevalence of 6-8% of pregnancies. Although the downregulation of lysyl oxidase (LOX) and LOX-like protein 2 (LOXL2), which leads to reduced trophoblast cell migration and invasion through activation of the TGF-β1/Smad3/collagen pathway, is relevant to preeclampsia, the mechanisms regulating differences in the gene expression of LOX and LOXL2 in placentas are not yet understood. This study aimed to investigate the mechanisms regulating differences in the gene expression of LOX and LOXL2 in placentas.

METHODS

The expression of miRNAs, LOX and LOXL2 in preeclamptic placentas and control placentas was analysed by qPCR. Localisation of miR29a and LOXL2 in preeclamptic placentas was performed by RNA-Fluorescence in-situ hybridization assay. The direct regulation of LOXL2 by miR-29a was assessed by dual-luciferase reporter assays in human extravillous trophoblast cells (HTR8/SVneo). Cell migration and invasion were evaluated by Transwell assays in HTR8/SVneo cells.

RESULTS

miR-29a expression was upregulated in preeclamptic placentas and negatively correlated with LOXL2 mRNA expression levels. RNA-Fluorescence in-situ hybridization assay revealed a clear overlap between miR-29a and LOXL2 in the placentas of preeclampic women. LOXL2 was a direct target gene of miR-29a, as confirmed by a dual-luciferase reporter assay in HTR8/SVneo trophoblast cells. miR-29a suppressed HTR8/SVneo trophoblast cell migration and invasion. LOXL2 overexpression reversed the inhibitory effects of miR-29a on HTR8/SVneo trophoblast cell migration and invasion.

CONCLUSION

Our results suggest that the upregulation of miR-29a suppresses the migration and invasion of HTR8/SVneo trophoblast cells by directly targeting LOXL2 in preeclampsia.

Roles of TGF-β Superfamily Proteins in Extravillous Trophoblast Invasion

Following embryo implantation, extravillous trophoblasts (EVTs) invade the maternal decidua to a certain extent during early pregnancy, which is critical for normal placentation and successful pregnancy in humans. Although sharing a similar protein structure, the transforming growth factor-β (TGF-β) superfamily members exert divergent functions in regulating EVT invasion, which contributes to a relative balance of TGF-β superfamily proteins in precisely modulating this process at the maternal-fetal interface during the first trimester of pregnancy. This review details recent advances in our understanding of the functions of TGF-β superfamily members and their corresponding receptors, signaling pathways, and downstream molecular targets in regulating human EVT invasion from studies using various in vitro or ex vivo experimental models. Also, the relevance of these discoveries about TGF-β superfamily members to adverse pregnancy outcomes is summarized. The application of 3D culture trophoblast organoids, single-cell sequencing, and microfluidic assays in EVT invasion studies will help better reveal the molecular mechanisms through which TGF-β superfamily members regulate human EVT invasion, shedding light on the development of innovative strategies for predicting, diagnosing, treating, and preventing adverse human pregnancy outcomes related to EVT invasion dysfunction.

MicroRNA-mRNA Networks in Pregnancy Complications: A Comprehensive Downstream Analysis of Potential Biomarkers

Pregnancy complications are a major cause of fetal and maternal morbidity and mortality in humans. The majority of pregnancy complications initiate due to abnormal placental development and function. During the last decade, the role of microRNAs (miRNAs) in regulating placental and fetal development has become evident. Dysregulation of miRNAs in the placenta not only affects placental development and function, but these miRNAs can also be exported to both maternal and fetal compartments and affect maternal physiology and fetal growth and development. Due to their differential expression in the placenta and maternal circulation during pregnancy complications, miRNAs can be used as diagnostic biomarkers. However, the differential expression of a miRNA in the placenta may not always be reflected in maternal circulation, which makes it difficult to find a reliable biomarker for placental dysfunction. In this review, we provide an overview of differentially expressed miRNAs in the placenta and/or maternal circulation during preeclampsia (PE) and intrauterine growth restriction (IUGR), which can potentially serve as biomarkers for prediction or diagnosis of pregnancy complications. Using different bioinformatics tools, we also identified potential target genes of miRNAs associated with PE and IUGR, and the role of miRNA-mRNA networks in the regulation of important signaling pathways and biological processes.

MicroRNA-138 improves LPS-induced trophoblast dysfunction through targeting RELA and NF-κB signaling

Preeclampsia is a pregnancy complication classified by new onset of elevated blood pressure and proteinuria after 20 weeks of gestation. During preeclampsia, extra villous trophoblasts fail to adequately invade the myometrial spiral arteries, leading to incomplete and impaired vessel transformation and initiating or aggravating preeclampsia. Although NF-κB and proinflammatory cytokines have been reported to be related to trophoblast dysfunction, the underlying mechanism remains unclear. Herein, we demonstrated the miR-138/RELA axis modulating the migratory ability, and invasive ability of HTR-8/SVneo and JEG-3 cells, as well as the inflammatory factor levels in response to LPS stimulation. miR-138 expression was upregulated in preeclampsia placenta and LPS-stimulated HTR-8/SVneo and JEG-3 cell lines. miR-138 overexpression rescued the migratory and invasive ability of HTR-8/SVneo and JEG-3 cells inhibited by LPS stimulation, and decreased LPS-induced TNF-α and IL-6 levels. By binding the 3'-UTR of RELA, miR-138 negatively regulated p65 expression. The silencing of p65 also improved LPS-induced HTR-8/SVneo and JEG-3 cell dysfunction and TNF-α and IL-6 levels. More importantly, p65 overexpression partially reversed the functions of miR-138 overexpression upon both cells, indicating that miR-138 exerted its biological effects through targeting RELA. In conclusion, miR-138 improves LPS-induced inflammation and oxidative stress on trophoblasts through targeting RELA and affecting NF-κB signaling. The miR-138/RELA axis might be involved in preeclampsia pathogenesis, which requires further in vivo and clinical researches.

Information on dysregulation of microRNA in placenta linked to preeclampsia

MicroRNAs are single-stranded, non-coding RNA molecules, regulate gene expression at the post-transcriptional level. They are expressed in the human body and have a significant impact on the different processes of pathological illness. A developing placenta undergoes a series of stages after successful fertilization, such as cell division, migration, adhesion, apoptosis, and angiogenesis. MicroRNAs dysregulation in placenta has been linked to pregnancy-related complications such as preeclampsia. Therefore, it is of interest to document known information (list of microRNA) on this issue in the development of biological tools for diagnosis, treatment and prevention of the disease.