Villous trophoblast apoptosis is elevated and restricted to cytotrophoblasts in pregnancies complicated by preeclampsia, IUGR, or preeclampsia with IUGR

Revealing the molecular landscape of human placenta: a systematic review and meta-analysis of single-cell RNA sequencing studies

BACKGROUND

With increasing significance of developmental programming effects associated with placental dysfunction, more investigations are devoted to improving the characterization and understanding of placental signatures in health and disease. The placenta is a transitory but dynamic organ adapting to the shifting demands of fetal development and available resources of the maternal supply throughout pregnancy. Trophoblasts (cytotrophoblasts, syncytiotrophoblasts, and extravillous trophoblasts) are placental-specific cell types responsible for the main placental exchanges and adaptations. Transcriptomic studies with single-cell resolution have led to advances in understanding the placenta's role in health and disease. These studies, however, often show discrepancies in characterization of the different placental cell types.

OBJECTIVE AND RATIONALE

We aim to review the knowledge regarding placental structure and function gained from the use of single-cell RNA sequencing (scRNAseq), followed by comparing cell-type-specific genes, highlighting their similarities and differences. Moreover, we intend to identify consensus marker genes for the various trophoblast cell types across studies. Finally, we will discuss the contributions and potential applications of scRNAseq in studying pregnancy-related diseases.

SEARCH METHODS

We conducted a comprehensive systematic literature review to identify different cell types and their functions at the human maternal-fetal interface, focusing on all original scRNAseq studies on placentas published before March 2023 and published reviews (total of 28 studies identified) using PubMed search. Our approach involved curating cell types and subtypes that had previously been defined using scRNAseq and comparing the genes used as markers or identified as potential new markers. Next, we reanalyzed expression matrices from the six available scRNAseq raw datasets with cell annotations (four from first trimester and two at term), using Wilcoxon rank-sum tests to compare gene expression among studies and annotate trophoblast cell markers in both first trimester and term placentas. Furthermore, we integrated scRNAseq raw data available from 18 healthy first trimester and nine term placentas, and performed clustering and differential gene expression analysis. We further compared markers obtained with the analysis of annotated and raw datasets with the literature to obtain a common signature gene list for major placental cell types.

OUTCOMES

Variations in the sampling site, gestational age, fetal sex, and subsequent sequencing and analysis methods were observed between the studies. Although their proportions varied, the three trophoblast types were consistently identified across all scRNAseq studies, unlike other non-trophoblast cell types. Notably, no marker genes were shared by all studies for any of the investigated cell types. Moreover, most of the newly defined markers in one study were not observed in other studies. These discrepancies were confirmed by our analysis on trophoblast cell types, where hundreds of potential marker genes were identified in each study but with little overlap across studies. From 35 461 and 23 378 cells of high quality in the first trimester and term placentas, respectively, we obtained major placental cell types, including perivascular cells that previously had not been identified in the first trimester. Importantly, our meta-analysis provides marker genes for major placental cell types based on our extensive curation.

WIDER IMPLICATIONS

This review and meta-analysis emphasizes the need for establishing a consensus for annotating placental cell types from scRNAseq data. The marker genes identified here can be deployed for defining human placental cell types, thereby facilitating and improving the reproducibility of trophoblast cell annotation.

Decidual macrophages and Hofbauer cells in fetal growth restriction

Placental macrophages, which include maternal decidual macrophages and fetal Hofbauer cells, display a high degree of phenotypical and functional plasticity. This provides these macrophages with a key role in immunologically driven events in pregnancy like host defense, establishing and maintaining maternal-fetal tolerance. Moreover, placental macrophages have an important role in placental development, including implantation of the conceptus and remodeling of the intrauterine vasculature. To facilitate these processes, it is crucial that placental macrophages adapt accordingly to the needs of each phase of pregnancy. Dysregulated functionalities of placental macrophages are related to placental malfunctioning and have been associated with several adverse pregnancy outcomes. Although fetal growth restriction is specifically associated with placental insufficiency, knowledge on the role of macrophages in fetal growth restriction remains limited. This review provides an overview of the distinct functionalities of decidual macrophages and Hofbauer cells in each trimester of a healthy pregnancy and aims to elucidate the mechanisms by which placental macrophages could be involved in the pathogenesis of fetal growth restriction. Additionally, potential immune targeted therapies for fetal growth restriction are discussed.

CircRNA_0088196 Regulates Trophoblast Proliferation and Apoptosis in Preeclampsia Through the miR-379-5p/HSPA5 Axis

Existing research has confirmed the dysregulation of circular RNA (circRNA) in a wide variety of human diseases. Thus, in this study, we explored the potential mechanism of circRNA_0088196 in preeclampsia (PE). We performed quantitative real-time PCR to examine circRNA_0088196 expression and verified the function of circRNA_0088196 in vitro using CCK-8, TUNEL, flow cytometry, and Western blotting analyses. Additionally, we studied the mechanism using dual-luciferase reporter gene experiments. The results of our research revealed the up-regulation of circRNA_0088196 in PE patients' placentas and Heat Shock 70 kDa Protein 5 (HSPA5)-stimulated trophoblast (HTR-8/SVneo) cells. An investigation of the mechanism also showed that there was a binding between miR-379-5p and circRNA_0088196. Additionally, circRNA_0088196 inhibited HTR-8/SVneo cell proliferation and promoted cell apoptosis via the miR-337-3p/HSPA5 axis, thereby facilitating PE. In vivo experiments indicated that circRNA_0088196 regulated HTR-8/SVneo cell production through miR-379-5p. Overall, the findings of this study illustrate that circRNA_0088196 interference promotes cell apoptosis and inhibits HTR-8/SVneo proliferation via the miR-379-5p/HSPA5 axis, thereby accelerating the development of PE.

Multiresolution semantic segmentation of biological structures in digital histopathology

Purpose

Semantic segmentation in high-resolution, histopathology whole slide images (WSIs) is an important fundamental task in various pathology applications. Convolutional neural networks (CNN) are the state-of-the-art approach for image segmentation. A patch-based CNN approach is often employed because of the large size of WSIs; however, segmentation performance is sensitive to the field-of-view and resolution of the input patches, and balancing the trade-offs is challenging when there are drastic size variations in the segmented structures. We propose a multiresolution semantic segmentation approach, which is capable of addressing the threefold trade-off between field-of-view, computational efficiency, and spatial resolution in histopathology WSIs.

Approach

We propose a two-stage multiresolution approach for semantic segmentation of histopathology WSIs of mouse lung tissue and human placenta. In the first stage, we use four different CNNs to extract the contextual information from input patches at four different resolutions. In the second stage, we use another CNN to aggregate the extracted information in the first stage and generate the final segmentation masks.

Results

The proposed method reported 95.6%, 92.5%, and 97.1% in our single-class placenta dataset and 97.1%, 87.3%, and 83.3% in our multiclass lung dataset for pixel-wise accuracy, mean Dice similarity coefficient, and mean positive predictive value, respectively.

Conclusions

The proposed multiresolution approach demonstrated high accuracy and consistency in the semantic segmentation of biological structures of different sizes in our single-class placenta and multiclass lung histopathology WSI datasets. Our study can potentially be used in automated analysis of biological structures, facilitating the clinical research in histopathology applications.

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

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

Sexual dimorphism in placental development and function: Comparative physiology with an emphasis on the pig

Across mammalian species, it has been demonstrated that sex influences birth weight, with males being heavier than females; a characteristic that can be observed from early gestation. Male piglets are more likely to be stillborn and have greater preweaning mortality than their female littermates, despite the additional maternal investment into male fetal growth. Given the conserved nature of the genome between the sexes, it is hypothesized that these developmental differences between males and females are most likely orchestrated by differential placental adaptation. This review summarizes the current understanding of fetal sex-specific differences in placental and endometrial structure and function, with an emphasis on pathways found to be differentially regulated in the pig including angiogenesis, apoptosis, and proliferation. Given the importance of piglet sex in agricultural enterprises, and the potential for skewed litter sex ratios, it is imperative to improve understanding of the relationship between fetal sex and molecular signaling in both the placenta and endometria across gestation.

Increased fetal microchimerism in immune and stem cell subsets in preeclampsia

PROBLEM

Preeclampsia (PE) is associated with an increased risk of maternal cardiovascular disease (CVD), however, it is unclear whether this is due to shared underlying physiology or changes which occur during the disease process. Fetal microchimerism (FMc) within the maternal circulation can durably persist decades after pregnancy, is known to occur at greater frequency in PE, and can potentially affect local and systemic immune programming, thus changes in cellular FMc may provide a mechanism for long-term health outcomes associated with PE.

METHOD OF STUDY

We investigated whether PE is associated with alterations in FMc immune and stem cell populations. We analyzed maternal peripheral blood mononuclear cells (PBMC) from PE cases (n = 16) and matched controls from normal pregnancies (n = 16), from which immune and stem cell subsets were isolated by flow cytometry. Genomic DNA was extracted from total PMBC and individual cell subsets, and FMc frequency was quantified by quantitative polymerase chain reaction assays targeting a fetal-specific non-shared polymorphism identified from family genotyping.

RESULTS

There was a significant increase in FMc concentration in immune cell subsets in PE cases compared to controls, predominantly in B cell, and NK cell lymphocyte populations. There was no significant difference in FMc frequency or concentration within the stem cell population between PE and controls.

CONCLUSIONS

The altered concentrations of immune cells within FMc in the maternal blood provides a potential mechanism for the inflammation which occurs during PE to induce long-lasting changes to the maternal immune system and may potentially promote chronic maternal disease.

Placental Mitochondrial Function and Dysfunction in Preeclampsia

The placenta is a vital organ of pregnancy, regulating adaptation to pregnancy, gestational parent/fetal exchange, and ultimately, fetal development and growth. Not surprisingly, in cases of placental dysfunction-where aspects of placental development or function become compromised-adverse pregnancy outcomes can result. One common placenta-mediated disorder of pregnancy is preeclampsia (PE), a hypertensive disorder of pregnancy with a highly heterogeneous clinical presentation. The wide array of clinical characteristics observed in pregnant individuals and neonates of a PE pregnancy are likely the result of distinct forms of placental pathology underlying the PE diagnosis, explaining why no one common intervention has proven effective in the prevention or treatment of PE. The historical paradigm of placental pathology in PE highlights an important role for utero-placental malperfusion, placental hypoxia and oxidative stress, and a critical role for placental mitochondrial dysfunction in the pathogenesis and progression of the disease. In the current review, the evidence of placental mitochondrial dysfunction in the context of PE will be summarized, highlighting how altered mitochondrial function may be a common feature across distinct PE subtypes. Further, advances in this field of study and therapeutic targeting of mitochondria as a promising intervention for PE will be discussed.

Single-Cell Immunobiology of the Maternal-Fetal Interface

Pregnancy success requires constant dialogue between the mother and developing conceptus. Such crosstalk is facilitated through complex interactions between maternal and fetal cells at distinct tissue sites, collectively termed the "maternal-fetal interface." The emergence of single-cell technologies has enabled a deeper understanding of the unique processes taking place at the maternal-fetal interface as well as the discovery of novel pathways and immune and nonimmune cell types. Single-cell approaches have also been applied to decipher the cellular dynamics throughout pregnancy, in parturition, and in obstetrical syndromes such as recurrent spontaneous abortion, preeclampsia, and preterm labor. Furthermore, single-cell technologies have been used during the recent COVID-19 pandemic to evaluate placental viral cell entry and the impact of SARS-CoV-2 infection on maternal and fetal immunity. In this brief review, we summarize the current knowledge of cellular immunobiology in pregnancy and its complications that has been generated through single-cell investigations of the maternal-fetal interface.

Analysis of commonly expressed genes between first trimester fetal heart and placenta cell types in the context of congenital heart disease

Congenital heart disease (CHD) is often associated with fetal growth abnormalities. During the first trimester of pregnancy, the heart and placenta develop concurrently, and share key developmental pathways. It is hypothesized that defective morphogenesis of either organ is synergistically linked. However, many studies determined to understand the mechanisms behind CHD overlook the contribution of the placenta. In this study, we aimed to identify commonly expressed genes between first trimester heart and placenta cells using two publicly available single cell sequencing databases. Using a systematic computational approach, we identified 328 commonly expressed genes between heart and placenta endothelial cells and enrichment in pathways including Vasculature Development (GO:0001944, FDR 2.90E−30), and Angiogenesis (GO:0001525, FDR 1.18E−27). We also found, in comparison with fetal heart endothelial cells, 197 commonly expressed genes with placenta extravillous trophoblasts, 128 with cytotrophoblasts and 80 with syncytiotrophoblasts, and included genes such as FLT1, GATA2, ENG and CDH5. Finally, comparison of first trimester cardiomyocytes and placenta cytotrophoblasts revealed 53 commonly expressed genes and enrichment in biological processes integral to cellular function including Cellular Respiration (GO:0045333; FDR 5.05E−08), Ion Transport (GO:0006811; FDR 2.08E−02), and Oxidation–Reduction Process (GO:0055114; FDR 1.58E−07). Overall, our results identify specific genes and cellular pathways common between first trimester fetal heart and placenta cells which if disrupted may concurrently contribute to the developmental perturbations resulting in CHD.

Mitochondrial Dysfunction in the Pathogenesis of Preeclampsia

PURPOSE OF REVIEW

Preeclampsia complicates 5-10% of all pregnancies and is a leading cause of maternal and perinatal mortality and morbidity. The placenta plays a pivotal role in determining pregnancy outcome by supplying the fetus with oxygen and nutrients and by synthesizing hormones. Placental function is highly dependent on energy supplied by mitochondria. It is well-known that preeclampsia is originated from placental dysfunction, although the etiology of it remains elusive.

RECENT FINDINGS

During the last three decades, substantial evidence suggests that mitochondrial abnormality is a major contributor to placental dysfunction. In addition, mitochondrial damage caused by circulating bioactive factors released from the placenta may cause endothelial dysfunction and subsequent elevation in maternal blood pressure. In this review, we summarize the current knowledge of mitochondrial abnormality in the pathogenesis of preeclampsia and discuss therapeutic approaches targeting mitochondria for treatment of preeclampsia.

scDeconv: an R package to deconvolve bulk DNA methylation data with scRNA-seq data and paired bulk RNA-DNA methylation data

Many DNA methylation (DNAm) data are from tissues composed of various cell types, and hence cell deconvolution methods are needed to infer their cell compositions accurately. However, a bottleneck for DNAm data is the lack of cell-type-specific DNAm references. On the other hand, scRNA-seq data are being accumulated rapidly with various cell-type transcriptomic signatures characterized, and also, many paired bulk RNA-DNAm data are publicly available currently. Hence, we developed the R package scDeconv to use these resources to solve the reference deficiency problem of DNAm data and deconvolve them from scRNA-seq data in a trans-omics manner. It assumes that paired samples have similar cell compositions. So the cell content information deconvolved from the scRNA-seq and paired RNA data can be transferred to the paired DNAm samples. Then an ensemble model is trained to fit these cell contents with DNAm features and adjust the paired RNA deconvolution in a co-training manner. Finally, the model can be used on other bulk DNAm data to predict their relative cell-type abundances. The effectiveness of this method is proved by its accurate deconvolution on the three testing datasets here, and if given an appropriate paired dataset, scDeconv can also deconvolve other omics, such as ATAC-seq data. Furthermore, the package also contains other functions, such as identifying cell-type-specific inter-group differential features from bulk DNAm data. scDeconv is available at: https://github.com/yuabrahamliu/scDeconv.

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.

IL‑1β‑induced pentraxin 3 inhibits the proliferation, invasion and cell cycle of trophoblasts in preeclampsia and is suppressed by IL‑1β antagonists

Pentraxin 3 (PTX3), a member of the c‑reactive protein family, is a long pentraxin protein and a pro‑inflammatory marker. However, the role of PTX3 in preeclampsia (PE) remains to be elucidated. Thus, the present study aimed to investigate the biological role and mechanisms underlying PTX3 in PE. In the present study, PTX3 was overexpressed in trophoblasts and the subsequent changes in cell proliferation, cycle distribution and invasion were observed using Cell Counting Kit‑8, flow cytometry and Transwell assays, respectively. Moreover, the expression levels of MMP2 and MMP9, proteins associated with the development of PE, were detected using reverse transcription‑quantitative PCR and western blot analysis. Following treatment with interleukin (IL)‑1β, the expression levels of PTX3 were measured. Furthermore, subsequent changes in cell proliferation, cycle distribution and invasion were investigated following overexpression of PTX3 and treatment with IL‑1 receptor antagonist (IL‑1Ra). Overexpression of PTX3 inhibited the proliferation, cycle and invasion of HTR‑8/SV neo and JEG3 cells. Moreover, treatment with IL‑1β increased the expression of PTX3 in HTR‑8/SV neo and JEG3 cells, which was suppressed following treatment with the IL‑1β antagonist. Following PTX3 overexpression and treatment with IL‑1Ra, the inhibitory effects of PTX3 overexpression alone on the invasion of HTR‑8/SV neo and JEG3 cells were attenuated. In conclusion, these results indicated that IL‑1β could induce PTX3 upregulation, which led to the inhibition of the proliferation, invasion and cell cycle of trophoblasts, thereby promoting the progression of PE.

Syncytiotrophoblast stress in preeclampsia: the convergence point for multiple pathways

Preeclampsia evolves in 2 stages: a placental problem that generates signals to the mother to cause a range of responses that comprise the second stage (preeclampsia syndrome). The first stage of early-onset preeclampsia is poor placentation, which we here call malplacentation. The spiral arteries are incompletely remodeled, leading to later placental malperfusion, relatively early in the second half of pregnancy. The long duration of the first stage (several months) is unsurprisingly associated with fetal growth restriction. The first stage of late-onset preeclampsia, approximately 80% of total cases, is shorter (several weeks) and part of a process that is common to all pregnancies. Placental function declines as it outgrows uterine capacity, with increasing chorionic villous packing, compression of the intervillous space, and fetal hypoxia, and causes late-onset clinical presentations such as "unexplained" stillbirths, late-onset fetal growth restriction, or preeclampsia. The second stages of early- and late-onset preeclampsia share syncytiotrophoblast stress as the most relevant feature that causes the maternal syndrome. Syncytiotrophoblast stress signals in the maternal circulation are probably the most specific biomarkers for preeclampsia. In addition, soluble fms-like tyrosine kinase-1 (mainly produced by syncytiotrophoblast) is the best-known biomarker and is routinely used in clinical practice in many locations. How the stress signals change over time in normal pregnancies indicates that syncytiotrophoblast stress begins on average at 30 to 32 weeks' gestation and progresses to term. At term, syncytiotrophoblast shows increasing markers of stress, including apoptosis, pyroptosis, autophagy, syncytial knots, and necrosis. We label this phenotype the "twilight placenta" and argue that it accounts for the clinical problems of postmature pregnancies. Senescence as a stress response differs in multinuclear syncytiotrophoblast from that of mononuclear cells. Syncytiotrophoblast irreversibly acquires part of the senescence phenotype (cell cycle arrest) when it is formed by cell fusion. The 2 pathways converge on the common pathologic endpoint, syncytiotrophoblast stress, and contribute to preeclampsia subtypes. We highlight that the well-known heterogeneity of the preeclampsia syndrome arises from different pathways to this common endpoint, influenced by maternal genetics, epigenetics, lifestyle, and environmental factors with different fetal and maternal responses to the ensuing insults. This complexity mandates a reassessment of our approach to predicting and preventing preeclampsia, and we summarize research priorities to maximize what we can learn about these important issues.

Impaired placental mitophagy and oxidative stress are associated with dysregulated BNIP3 in preeclampsia

Preeclampsia (PE) is a severe multisystem pregnancy complication characterized by gestational hypertension and proteinuria. Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) is a mediator of mitophagy and has been proven to be associated with PE, but the mechanism is not well understood. This study aimed to investigate the role of BNIP3 in PE. Placentae from preeclamptic and normal pregnancies were analyzed by western-blot and transmission electron microscopy to quantify the level of BNIP3 expression and observe the organelle morphologies. Trophoblast cells with knockdown BNIP3 were analyzed by western-blot, immunofluorescence, flow cytometry, migration and invasion assays. BNIP3 expression was suppressed in PE patients. Impaired autophagy and increased mitochondrial damage were observed in PE placentae when compared with normal placentae. Suppression of BNIP3 inhibited Beclin-1 expression and reduced the transformation of LC3-I to LC3-II. In the knockdown BNIP3 group, p62 was overexpressed, ROS accumulated and the apoptotic process was elevated under oxidative stress condition. The knockdown of BNIP3 reduced the colocalization of GFP-LC3 and mitochondria. The findings of this study suggest that dysregulated BNIP3 is associated with impaired mitophagy, oxidative stress, and apoptosis in PE. The study provides new insights into the role of BNIP3 in the pathophysiology of PE.

The balance between cell survival and death in the placenta: Do neurotrophins have a role?

Neurotrophins (NT) are a closely related family of growth factors, which regulate the nervous system's development, maintenance, and function. Although NTs have been well studied in neuronal cells, they are also expressed in the placenta. Despite their suggested role in regulating fetoplacental development, their precise functional significance in the placenta remains elusive. NT activate two different classes of receptors. These include the Trk, tropomyosin-related kinase family of high-affinity tropomyosin-related kinase receptors, which induces cell survival, and the p75NTR, p75 neurotrophin receptor, a member of the tumor necrosis factor(TNF) receptor superfamily, which induces apoptosis in neuronal cells. Mature NT molecule results from proteolysis of a biologically active precursor form called pro-neurotrophins (pro-NT) by the intracellular proprotein convertase or furin. Pro-NTs have a regulatory role in determining cell survival and apoptosis. Here, we review the literature on the expression and functions of NTs and their receptors in the placenta and discuss their possible role in placental tissue development and apoptosis. The possible implications of imbalance in pro-NT and mature-NT levels for fetoplacental development are also discussed.Abbreviations AGE/ALEs: Advanced glycation/lipoxidation end products; Bax: Bcl 2 Associated X; Bcl-2: B-cell lymphoma 2; BDNF: Brain-derived neurotrophic factor; FAS/FASL: Fas cell surface death receptor/ ligand; IUGR: Intrauterine growth restriction; JNK: c-Jun amino-terminal kinase; MAP: mitogen-activated protein k; mRNA: Messenger ribonucleic acid; NGF: Nerve growth factor; NT: Neurotrophins; NRAGE: Neurotrophin receptor-interacting MAGE homolog; NRIF: Neurotrophin receptor interacting factor; PE: Preeclampsia; PI3k: Phosphoinositide 3- kinase; PLC: Phospholipase C; p75NTR: p75 neurotrophin receptor; Pro-NT: Pro-neurotrophins; PTB: Preterm birth; p53: Tumor protein p53; TNF: Tumor necrosis factor; TRAF: TNFR-associated factors; Trk: Tropomyosin-related kinase; siRNA: small interfering ribonucleic acid.

Placental Findings in Preterm and Term Preeclampsia: An Integrative Review of the Literature

INTRODUCTION

 Preeclampsia (PE) is a pregnancy complication associated with increased maternal and perinatal morbidity and mortality. The disease presents with recent onset hypertension (after 20 weeks of gestation) and proteinuria, and can progress to multiple organ dysfunction, with worse outcomes among early onset preeclampsia (EOP) cases (< 34 weeks). The placenta is considered the root cause of PE; it represents the interface between the mother and the fetus, and acts as a macromembrane between the two circulations, due to its villous and vascular structures. Therefore, in pathological conditions, macroscopic and microscopic evaluation can provide clinically useful information that can confirm diagnosis and enlighten about outcomes and future therapeutic benefit.

OBJECTIVE

 To perform an integrative review of the literature on pathological placental findings associated to preeclampsia (comparing EOP and late onset preeclampsia [LOP]) and its impacts on clinical manifestations.

RESULTS

 Cases of EOP presented worse maternal and perinatal outcomes, and pathophysiological and anatomopathological findings were different between EOP and LOP placentas, with less placental perfusion, greater placental pathological changes with less villous volume (villous hypoplasia), greater amount of trophoblastic debris, syncytial nodules, microcalcification, villous infarcts, decidual arteriolopathy in EOP placentas when compared with LOP placentas. Clinically, the use of low doses of aspirin has been shown to be effective in preventing PE, as well as magnesium sulfate in preventing seizures in cases of severe features.

CONCLUSION

 The anatomopathological characteristics between EOP and LOP are significantly different, with large morphological changes in cases of EOP, such as hypoxia, villous infarctions, and hypoplasia, among others, most likely as an attempt to ascertain adequate blood flow to the fetus. Therefore, a better understanding of the basic macroscopic examination and histological patterns of the injury is important to help justify outcomes and to determine cases more prone to recurrence and long-term consequences.

Assessment of apoptosis and appearance of hepatocyte growth factor in placenta at different gestational ages: A cross-sectional study

Background

Fetal growth is determined by the interaction between mother and fetus using the placental interface throughout the pregnancy.

Objective

To research apoptosis and appearance of hepatocyte growth factor (HGF) in placentas of different gestational ages and to describe the anthropometrical and clinical indices of mothers and newborns.

Materials and Methods

The study material was obtained from 53 human immunodeficiency virus negative pregnant women of legal age without systemic diseases. The staining of placental apoptotic cells was processed by a standard in situ cell death detection kit. The detection of HGF was provided by the ImmunoCruz goat ABC Staining System protocol sc-2023. Relative distribution of positive structures was evaluated using the semiquantitative counting method.

Results

The mean rank value of the amount of HGF-containing cells (cytotrophoblasts, syncytiotrophoblasts, extravillous trophoblasts, Höfbauer cells, and cells of extraembryonic mesoderm) was 1.61 ± 0.94. Apoptotic cells (cytotrophoblasts, syncytiotrophoblasts, extravillous trophoblasts, and cells of extraembryonic mesoderm) were found in all placental samples of various gestational ages (term 13.00 ± 13.05 and preterm 27.00 ± 18.25); in general, their amount decreased with advancing gestational age of the placenta (p < 0.01).

Conclusion

Weight of a placenta directly depends on the gestational age and correlates with the main fetal anthropometrical parameters (weight, length, and head and chest circumferences). The decrease in HGF-containing and apoptotic cells with advancing gestation depends on the adaptation potential of the placenta, proving the other ways of cellular disposition.

Syncytiotrophoblast stress in early onset preeclampsia: The issues perpetuating the syndrome

Preeclampsia is a pregnancy-specific syndrome characterized by a sudden increase in blood pressure accompanied by proteinuria and/or maternal multi-system damage associated to poor fetal outcome. In early-onset preeclampsia, utero-placental perfusion is altered, causing constant and progressive damage to the syncytiotrophoblast, generating syncytiotrophoblast stress. The latter leads to the detachment and release of syncytiotrophoblast fragments, anti-angiogenic factors and pro-inflammatory molecules into maternal circulation, resulting in the emergence and persistence of the characteristic symptoms of this syndrome during pregnancy. Therefore, understanding the origin and consequences of syncytiotrophoblast stress in preeclampsia is vital to develop new therapeutic alternatives, focused on reducing the burden of this syndrome. In this review, we describe five central characteristics of syncytial stress that should be targeted or prevented in order to reduce preeclampsia symptoms: histological alterations, syncytiotrophoblast damage, antiangiogenic protein export, placental deportation, and altered syncytiotrophoblast turnover. Therapeutic management of these characteristics may improve maternal and fetal outcomes.

From inhibition of trophoblast cell invasion to proapoptosis: what are the potential roles of kisspeptins in preeclampsia?

Preeclampsia (PE) is a life-threatening human gestational syndrome with incompletely understood etiopathogenesis. The disorder has a spectrum of clinical features, likely due to a complex interaction between maternal predisposing factors and abnormalities at the maternal-fetal interface. Poor trophoblast cell invasion, inadequate uterine vascular remodeling, and placental hypoperfusion are considered as key placental events leading to PE. Kisspeptins, a family of small peptides derived from the KISS1 gene, have been implicated in the development of this syndrome. Most studies of kisspeptin expression in PE have reported an upregulation of kisspeptins and/or their cognate receptor in preeclamptic placentas. Conversely, maternal peripheral blood concentration of kisspeptins is reportedly lower in PE than in uncomplicated pregnancies. This apparent paradox remains to be further elucidated. Although kisspeptins were initially known for inhibiting cellular migration and invasion, other biological activities attributed to these peptides include neuroendocrine regulation of reproduction, metabolism regulation, inhibition of angiogenesis, and induction of apoptosis. This review summarizes the current knowledge on expression and biological activity of kisspeptins at the maternal-fetal interface in the context of PE.

Silencing lncRNA-DGCR5 increased trophoblast cell migration, invasion and tube formation, and inhibited cell apoptosis via targeting miR-454-3p/GADD45A axis

Long noncoding RNA (lncRNA)-DGCR5 has been recognized as a potential tumor progression regulator, while its expression and specific functions in preeclampsia (PE) development remain unveiled. The expressions of miR-454-3p, lncRNA-DiGeorge syndrome critical region gene 5 (DGCR5) and growth arrest and DNA damage protein-inducible 45A (GADD45A) in placental tissues from PE patients or HTR-8/SVneo cells were assessed by Western blot or qRT-PCR. Dual-luciferase reporter assay determined the binding relations between miR-454-3p and GADD45A and between miR-454-3p and lncRNA-DGCR5. The viability, apoptosis, migration, invasiveness and tube formation of HTR-8/SVneo cell were evaluated using cell counting kit (CCK)-8, Annexin-V/Propidium iodide staining, wound healing, transwell and tube formation assays, respectively. miR-454-3p was low-expressed in PE tissue, and upregulation of miR-454-3p increased viability and promoted migration, invasion and tube formation in HTR-8/SVneo cells while inhibiting apoptosis. Then, miR-454-3p was found to directly target GADD45A which was high-expressed in PE tissues. Overexpressing GADD45A decreased the viability and inhibited the migration, invasion and tube formation of HTR-8/SVneo cells while enhancing apoptosis, and it neutralized the effect of miR-454-3p upregulation. In turn, miR-454-3p upregulation reversed the effect of GADD45A overexpression. Meanwhile, miR-454-3p could also target lncRNA-DGCR5. Silencing lncRNA-DGCR5 increased miR-454-3p expression and cell viability and promoted migration, invasion and tube formation in HTR-8/SVneo cells while inhibiting apoptosis, and it counteracted the effect of miR-454-3p downregulation. As usual, miR-454-3p downregulation reversed the effect of lncRNA-DGCR5 silencing. To conclude, silencing lncRNA-DGCR5 increased viability, promoted migration, invasion and tube formation, and inhibited apoptosis in HTR-8/SVneo cells by rescuing the inhibition of GADD45A expression caused by miR-454-3p.

Association of β-arrestin1 and p53-Mdm2 signaling in the development of missed abortion

BACKGROUND

Missed abortion is a peculiar form of spontaneous abortion before 20 weeks' gestation. The definite etiology and pathogenesis are not fully understood. Recent studies have demonstrated that p53/Mdm2-mediated ubiquitination of the IGF-1R may be closely related to G-protein-coupled receptor kinases (GRK)/β-arrestin1 system. Our previous studies have confirmed that the elevated expression of p53 and Mdm2 may be responsible for apoptosis during missed abortion. However, there was no information surrounding β-arrestin1 in missed abortion.

METHODS

The mRNA levels of β-arrestin1 in villous samples of 30 missed abortion patients and 31 healthy controls were determined by real-time quantitative polymerase chain reaction (PCR). Immunohistochemistry was used to explore the expression and location of β-arrestin1, p53, Mdm2, VEGF and HIF-lα in trophoblasts. Transwell assays were performed to examine the influences of β-arrestin1 expression on cell invasion. Furthermore, we tested the effect of β-arrestin1 on the expression of p53, Mdm2, ERK, AKT and NF-κB.

RESULTS

The expression of β-arrestin1 in the villous samples of missed abortion group was dramatically lower than control group by quantitative real-time-PCR and immunohistochemistry. Furthermore, the patients with missed abortion showed significantly higher levels of p53, Mdm2, HIF-lα and lower level of VEGF than healthy controls by immunohistochemistry. Functional studies showed that suppression of β-arrestin1 in HTR-8 cells inhibited cell invasion. The protein expressions of ERK and AKT in HTR-8 cells were significantly downregulated by reducing the expression of β-arrestin1, while the expressions of p53, Mdm2, NF-κB were enhanced. Overexpression of β-arrestin1 exhibited the adverse effect.

CONCLUSION

Our data indicated that β-arrestin1 play an important role in maintaining the maternal-fetal tolerance, the decreased expression of β-arrestin1 in the villous samples may be related with the development of missed abortion.

Expression of Caspases in the Pig Endometrium Throughout the Estrous Cycle and at the Maternal-Conceptus Interface During Pregnancy and Regulation by Steroid Hormones and Cytokines

Caspases, a family of cysteine protease enzymes, are a critical component of apoptotic cell death, but they are also involved in cellular differentiation. The expression of caspases during apoptotic processes in reproductive tissues has been shown in some species; however, the expression and regulation of caspases in the endometrium and placental tissues of pigs has not been fully understood. Therefore, we determined the expression of caspases CASP3, CASP6, CASP7, CASP8, CASP9, and CASP10 in the endometrium throughout the estrous cycle and pregnancy. During the estrous cycle, the expression of all caspases and during pregnancy, the expression of CASP3, CASP6, and CASP7 in the endometrium changed in a stage-specific manner. Conceptus and chorioallantoic tissues also expressed caspases during pregnancy. CASP3, cleaved-CASP3, and CASP7 proteins were localized to endometrial cells, with increased levels in luminal and glandular epithelial cells during early pregnancy, whereas apoptotic cells in the endometrium were limited to some scattered stromal cells with increased numbers on Day 15 of pregnancy. In endometrial explant cultures, the expression of some caspases was affected by steroid hormones (estradiol-17β and/or progesterone), and the cytokines interleukin-1β and interferon-γ induced the expression of CASP3 and CASP7, respectively. These results indicate that caspases are dynamically expressed in the endometrium throughout the estrous cycle and at the maternal-conceptus interface during pregnancy in response to steroid hormones and conceptus signals. Thus, caspase action could be important in regulating endometrial and placental function and epithelial cell function during the implantation period in pigs.

ELABELA alleviates syncytiotrophoblast hypoxia/reoxygenation injury and preeclampsia-like symptoms in mice by reducing apoptosis

INTRODUCTION

Preeclampsia (PE) is associated with increased syncytiotrophoblast apoptosis. ELABELA (ELA) is a circulating hormone secreted by the placenta. Here, we investigated the involvement of ELA in the pathogenesis of PE.

METHODS

We measured ELA expression in the placental villi of patients with severe PE and healthy controls. A cellular model of hypoxia and reoxygenation was used to simulate PE hypoxia, and changes in the proliferation and apoptosis of trophoblasts in response to different ELA concentrations were measured. In addition, we used NG-nitro-l-arginine methyl ester (l-NAME) to generate a mouse model of pregnancy-induced hypertension and explore whether ELA can improve the symptoms of PE.

RESULTS

ELA expression was decreased in severe PE. ELA promoted the proliferation of BeWo cells and improved the decreased cell proliferation rate after hypoxia/reoxygenation injury. ELA reversed the phenotypes of l-NAME-induced PE mice and regulated the expression of mouse placental apoptosis factors.

DISCUSSION

ELA reduced apoptosis in BeWo cells and improved PE-like symptoms in mice, suggesting its value as a potential novel treatment for PE.

Up-regulation of LncRNA NEAT1 induces apoptosis of human placental trophoblasts

The trophoblast apoptosis induced by placental oxidative stress is a contributor to the pathological development of preeclampsia (PE), whereas the molecular mechanism remains unclear. In this study, we explored the role and mechanism of Long non-coding RNA (LncRNA) NEAT1 in trophoblasts apoptosis. In the placenta tissues of PE patients and H₂O₂-treated human trophoblast cell line HTR-8/SVneo, the expressions of LncRNA NEAT1, p53, and estrogen receptor α (ESRα) were increased whereas miR-18a-5p expression was decreased. ESRα expression was up-regulated by LncRNA NEAT1 overexpression and down-regulated by miR-18a-5p overexpression in HTR-8/SVneo cells. LncRNA NEAT1 could release ESRα expression through sponging miR-18a-5p and the transcription of LncRNA NEAT1 was promoted by p53. miR-18a-5p overexpression suppressed H₂O₂-induced cell apoptosis in HTR-8/SVneo cells, while the inhibitory effect of miR-18a-5p overexpression on cell apoptosis was abrogated by LncRNA NEAT1 overexpression. In summary, LncRNA NEAT1 transcription was induced by p53 under oxidative stress condition, the high expression of LncRNA NEAT1 subsequently increased ESRα expression by sponging miR-18a-5p, thus inducing trophoblasts apoptosis.

Elevated miR-23a impairs trophoblast migration and invasiveness through HDAC2 inhibition and NF-κB activation

Preeclampsia (PE) is a pregnancy-specific disorder characterized by the onset of hypertension and proteinuria with onset after the 20th week of gestation. The pathogenesis of PE is attributed to increased trophoblast cell death and poor trophoblast migration/invasiveness. This study investigates the function of microRNA-23a (miR-23a) in PE and its effects on migration and invasion of trophoblast cells HTR-8/SVneo. We found higher expression of miR-23a in placental tissue samples from PE pregnant women compared to samples from normal pregnant women. Enhancing miR-23a expression by its specific mimic reduced HTR-8/SVneo cell migration and invasion and increased HTR-8/SVneo cell apoptosis. The dual-luciferase reporter gene assay revealed miR-23a binding with HDAC2. We found that HDAC2 was poorly expressed in placental tissue samples from PE pregnant women, and its expression correlated inversely with miR-23a expression. HTR-8/SVneo cells showed diminished HDAC2 expression upon miR-23a elevation and increased HDAC2 expression upon miR-23a inhibition. Lentivirus-mediated HDAC2 knockdown mimicked the effects of miR-23a on HTR-8/SVneo cells and led to NF-κB activation. Similarly, HDAC2 overexpression and NF-κB inhibition both abrogated the effects of miR-23a on HTR-8/SVneo cells, suggesting that miR-23a reduced HTR-8/SVneo cell migration and invasion and increased HTR-8/SVneo cell apoptosis by HDAC2 inhibition and NF-κB activation. In summary, these results support a novel role of miR-23b in invasion and apoptosis of trophoblast cells, and imply that targeting miR-23b may be a new avenue for treating PE.

L-carnitine increases cell proliferation and amino acid transporter expression via the activation of insulin-like growth factor I signaling pathway in rat trophoblast cells

Early embryo implantation and development is primarily determined by the homeostasis between cellular apoptosis and proliferation as well as placental nutrient transporters. Recent studies showed that L-carnitine enhances female reproductive performance. However, the potential function of L-carnitine on placenta is largely unknown. In our study, primary rat trophoblast cells were separated and cultured for 12 hr in medium containing various concentrations of L-carnitine (0, 1, 10, and 50 mM). Placenta trophoblast cells treated with 50 mM L-carnitine increased the proportion of cells in S phase of the cell cycle (p < .05). In addition, live cell percentage was increased when treated with either 10 mM or 50 mM L-carnitine, which was accompanied with decreased necrotic cells, late apoptotic cells, and early apoptotic cells (p < .05). Compared with the control treatment, the mRNA expression of insulin-like growth factor I (IGF-1) and insulin-like growth factor I receptor (IGF-1R) was higher in rat placenta trophoblasts treated with either 10 mM or 50 mM L-carnitine (p < .05). Similarly, sodium-dependent neutral amino acid transporter (SNAT)-1 and SNAT2 were up-regulated in both mRNA and protein levels when trophoblast cells were treated with 50 mM L-carnitine (p < .05). Inhibiting downstream targets (Akt or ERK signaling pathways) of IGF-1 signaling pathway partially blocked the effect the L-carnitine-induced increase in protein abundances of SNAT1 and SNAT2. Collectively, our data showed protective role of L-carnitine on placenta trophoblast cells through the involvement of IGF-1 signaling pathway.

TLR3 expression by maternal and fetal cells at the maternal-fetal interface in normal and preeclamptic pregnancies

Inflammation and oxidative stress at the maternal-fetal interface characterize the placental dysfunction that underlies the pregnancy disorder preeclampsia. Specialized fetal trophoblasts directly interact with leukocytes at both sites of the maternal-fetal interface; the uterine wall decidua; and the placenta. TLR3 has been implicated in the harmful inflammation at the maternal-fetal interface in preeclampsia, but the cellular involvement in the decidua and placenta has not been determined. This study aimed to characterize and quantify cell-specific TLR3 expression and function at the maternal-fetal interface in normal and preeclamptic pregnancies. TLR3 expression was assessed by immunohistochemistry and quantified by a novel image-based and cell-specific quantitation method. TLR3 was expressed at the maternal-fetal interface by all decidual and placental trophoblast types and by maternal and fetal leukocytes. Placental, but not decidual, TLR3 expression was significantly higher in preeclampsia compared to normal pregnancies. This increase was attributed to placental intravillous tissue and associated with both moderate and severe placental dysfunction. TLR3 pathway functionality in the decidua and placenta was confirmed by TLR3 ligand-induced cytokine response, but the TLR3 expression levels did not correlate between the two sites. In conclusion, functional TLR3 was broadly expressed by maternal and fetal cells at both sites of the maternal-fetal interface and the placental intravillous expression was increased in preeclampsia. This suggests TLR3-mediated inflammatory involvement with local regulation at both sites of the maternal-fetal interface in normal and preeclamptic pregnancies.

The Role of LIN28-let-7-ARID3B Pathway in Placental Development

Placental disorders are a major cause of pregnancy loss in humans, and 40–60% of embryos are lost between fertilization and birth. Successful embryo implantation and placental development requires rapid proliferation, invasion, and migration of trophoblast cells. In recent years, microRNAs (miRNAs) have emerged as key regulators of molecular pathways involved in trophoblast function. A miRNA binds its target mRNA in the 3ʹ-untranslated region (3ʹ-UTR), causing its degradation or translational repression. Lethal-7 (let-7) miRNAs induce cell differentiation and reduce cell proliferation by targeting proliferation-associated genes. The oncoprotein LIN28 represses the biogenesis of mature let-7 miRNAs. Proliferating cells have high LIN28 and low let-7 miRNAs, whereas differentiating cells have low LIN28 and high let-7 miRNAs. In placenta, low LIN28 and high let-7 miRNAs can lead to reduced proliferation of trophoblast cells, resulting in abnormal placental development. In trophoblast cells, let-7 miRNAs reduce the expression of proliferation factors either directly by binding their mRNA in 3ʹ-UTR or indirectly by targeting the AT-rich interaction domain (ARID)3B complex, a transcription-activating complex comprised of ARID3A, ARID3B, and histone demethylase 4C (KDM4C). In this review, we discuss regulation of trophoblast function by miRNAs, focusing on the role of LIN28-let-7-ARID3B pathway in placental development.

The placenta in fetal growth restriction: What is going wrong?

The placenta is essential for the efficient delivery of nutrients and oxygen from mother to fetus to maintain normal fetal growth. Dysfunctional placental development underpins many pregnancy complications, including fetal growth restriction (FGR) a condition in which the fetus does not reach its growth potential. The FGR placenta is smaller than normal placentae throughout gestation and displays maldevelopment of both the placental villi and the fetal vasculature within these villi. Specialized epithelial cells called trophoblasts exhibit abnormal function and development in FGR placentae. This includes an altered balance between proliferation and apoptotic death, premature cellular senescence, and reduced colonisation of the maternal decidual tissue. Thus, the placenta undergoes aberrant changes at the macroscopic to cellular level in FGR, which can limit exchange capacity and downstream fetal growth. This review aims to compile stereological, in vitro, and imaging data to create a holistic overview of the FGR placenta and its pathophysiology, with a focus on the contribution of trophoblasts.

A bibliometric analysis of Intrauterine Growth Restriction research

Intrauterine growth restriction (IUGR) is not a new subject in pregnancy. Nevertheless, this concept has newly begun to be integrated into pregnancy studies. We recognized articles that were published in English from 1977 to 2019 through electronic searches of the Web of Science™ database. The WoS database was searched for all published articles that compared preeclampsia from 1977 to January 2020. About 1469 documents in obstetrics and gynecology areas were analyzed in WoS database. VOSviewer software was employed to visualize the networks. The survey resulted in a 1469 published documents from 1977 to 2020. 'Gratacos' from Spain and 'Cetin' from Italy contributed the most publications. The greatest contribution came from the 'USA' (n = 498), 'Italy' (n = 155), and 'England' (n = 147). Furthermore, our results found that among these journals, the 'AJOG' (n = 318) and the 'Reproductive Sciences' (n = 209) published the largest number of papers. The top 100 most cited papers showed that 30% were reported in the 'AJOG'. About half the articles were published in the last decade and the most common studies were research paper (77%). The co-occurrence and co-citation analysis showed that the study formed four clusters. Finally, the strategic map was designed. We found that there existed an increasing trend in the large amount of publication on IUGR from 1977 to 2020. The number of studies in IUGR has substantially improved in the last decade. Authors from the 'USA' appeared the most proactive in addressing the IUGR area. By studying these articles, we propose important to support not only for grinding the IUGR challenges field but also for designing a new trend in this area.

Comparative gene expression analysis of Fas and related genes in preeclamptic and healthy women: A cross-sectional study

BACKGROUND

Preeclampsia is a hypertensive disorder of pregnancy affecting about 2-10% pregnancies worldwide. mRNA expression of tumor necrosis factor alpha (TNF- α ), Fas, and FasL have been reported to be altered in placental bed in preeclamptic pregnancies. We hypothesized that the expression of these genes is also altered in peripheral blood mononuclear cells (PBMCs) in preeclampsia.

OBJECTIVE

To compare the expression of Fas receptor and related genes in PBMCs of preeclamptic and normotensive pregnant women.

MATERIALS AND METHODS

A cross-sectional comparative study comprising of 18 cases and 18 controls was designed. 5 ml of venous blood was drawn and collected considering aseptic measures. Buffy coat was separated by centrifugation and stored at -20°C. Favor Prep total RNA Isolation Kit (Favorgen, Taiwan) was used for RNA extraction. The mRNA expression of TNF- α , Fas, and FasL was measured by real-time polymerase chain reaction in PBMCs in preeclamptic and normal pregnancies.

RESULTS

A significant increase in mRNA expression of TNF- α , Fas, and FasL (p ≤ 0.001) was observed in PBMCs of preeclamptic pregnancies compared to the control group (p ≤ 0.001). Moreover, a significant positive correlation was found between the TNF- α mRNA expression and Fas and FasL (p ≤ 0.001).

CONCLUSION

The results lead to the conclusion that mRNA expression of TNF- α , Fas, and FasL in the maternal PBMCs is altered in preeclamptic pregnancies and might contribute to the pathogenesis of the disease.

Rosiglitazone augments antioxidant response in the human trophoblast and prevents apoptosis†

Insufficient perfusion of the trophoblast by maternal blood is associated with an increased generation of reactive oxygen species and complications of the placenta. In this study, we first examined whether rosiglitazone, an agonist of the peroxisome proliferator-activated receptor-γ (PPARγ), protects the human trophoblast from oxidative injury by regulating key antioxidant proteins, catalase (CAT) and the superoxide dismutases (SOD1 and SOD2). In first trimester placental explants, localization of CAT was limited to cytotrophoblasts, whereas SOD1 was expressed in both the cyto- and syncytiotrophoblasts. In first trimester placental explants, hypoxia decreased the expression of both SOD1 and SOD2, and increased apoptosis. Treatment with rosiglitazone dose-dependently upregulated anti-oxidative CAT and SOD2, and rescued hypoxic injury in first trimester villous explants and JEG-3 cells, strongly suggesting the involvement of the PPARγ in regulating their expressions. Rosiglitazone facilitated transcription activity of PPARγ, and enhanced promotor binding, increased transcriptional activity at the CAT promoter, and elevated protein expression/activity. Treatment of hypoxic JEG-3 cells with rosiglitazone resulted in mitochondrial membrane potential increase and a reduction of caspase 9 and caspase 3 activity which is consistent with improved cell survival. To complement PPARγ activation data, we also utilized the antagonist (SR-202) and siRNA to suppress PPARγ expression and demonstrate the specific role of PPARγ in reducing ROS and oxidative stress. Ex vivo examination of term human placenta revealed lower expression of antioxidant proteins in pathologic compared to healthy placental tissues, which could be rescued by rosiglitazone, indicating that rosiglitazone can improve survival of the trophoblast under pathological conditions. These findings provide evidence that the PPARγ pathway directly influences cellular antioxidants production and the pathophysiology of placental oxidative stress.

Pregnancy-associated venous insufficiency course with placental and systemic oxidative stress

The development of lower extremity venous insufficiency (VI) during pregnancy has been associated with placental damage. VI is associated with increased oxidative stress in venous wall. We have investigated potential disturbance/dysregulation of the production of reactive oxygen species (ROS) in placenta and its eventual systemic effects through the measurement of malondialdehyde (MDA) plasma levels in women with VI. A total of 62 women with VI and 52 healthy controls (HCs) were studied. Levels of nicotinamide adenine dinucleotide phosphate-oxidase 1 (NOX1), 2 (NOX2), inducible nitric oxide synthase (iNOS), endothelial (eNOS), poly(ADP-ribose) polymerase PARP (PARP) and ERK were measured in placental tissue with immunohistochemistry and RT-qPCR. Plasma and placental levels of MDA were determined by colorimetry at the two study times of 32 weeks of gestation and post-partum. Protein and gene expression levels of NOX1, NOX2, iNOS, PARP and ERK were significantly increased in placentas of VI. eNOS activity was low in both study groups, and there were no significant differences in gene or protein expression levels. Women with VI showed a significant elevation of plasma MDA levels at 32 weeks of gestation, and these levels remained elevated at 32 weeks post-partum. The MDA levels were significantly higher in placentas of women with VI. Placental damage that was found in the women with VI was characterized by overexpression of oxidative stress markers NOX1, NOX2, and iNOS, as well as PARP and ERK. Pregnant women with VI showed systemic increases in oxidative stress markers such as plasma MDA levels. The foetuses of women with VI had a significant decrease in their venous pH as compared to those from HC women. The situation of oxidative stress and cellular damage created in the placenta is in coexpression with the production of a pH acidification.

Heightened susceptibility: A review of how pregnancy and chemical exposures influence maternal health

Pregnancy is a unique period when biological changes can increase sensitivity to chemical exposures. Pregnant women are exposed to multiple environmental chemicals via air, food, water, and consumer products, including flame retardants, plasticizers, and pesticides. Lead exposure increases risk of pregnancy-induced hypertensive disorders, although women's health risks are poorly characterized for most chemicals. Research on prenatal exposures has focused on fetal outcomes and less on maternal outcomes. We reviewed epidemiologic literature on chemical exposures during pregnancy and three maternal outcomes: preeclampsia, gestational diabetes, and breast cancer. We found that pregnancy can heighten susceptibility to environmental chemicals and women's health risks, although variations in study design and exposure assessment limited study comparability. Future research should include pregnancy as a critical period for women's health. Incorporating biomarkers of exposure and effect, deliberate timing and method of measurement, and consistent adjustment of potential confounders would strengthen research on the exposome and women's health.

The Placental Basis of Fetal Growth Restriction

Placental dysfunction is a major contributing factor to fetal growth restriction. Placenta-mediated fetal growth restriction occurs through chronic fetal hypoxia owing to poor placental perfusion through a variety of mechanisms. Maternal vascular malperfusion is the most common placental disease contributing to fetal growth restriction; however, the role of rare placental diseases should not be overlooked. Although the features of maternal vascular malperfusion are identifiable on placental pathology, antepartum diagnostic methods are evolving. Placental imaging and uterine artery Doppler, used in conjunction with angiogenic growth factors (specifically placenta growth factor and soluble fms-like tyrosine kinase-1), play an increasingly important role.

Pyroptosis is a critical inflammatory pathway in the placenta from early onset preeclampsia and in human trophoblasts exposed to hypoxia and endoplasmic reticulum stressors

Systemic manifestation of preeclampsia (PE) is associated with circulating factors, including inflammatory cytokines and damage-associated molecular patterns (DAMPs), or alarmins. However, it is unclear whether the placenta directly contributes to the increased levels of these inflammatory triggers. Here, we demonstrate that pyroptosis, a unique inflammatory cell death pathway, occurs in the placenta predominantly from early onset PE, as evidenced by elevated levels of active caspase-1 and its substrate or cleaved products, gasdermin D (GSDMD), IL-1β, and IL-18. Using cellular models mimicking pathophysiological conditions (e.g., autophagy deficiency, hypoxia, and endoplasmic reticulum (ER) stress), we observed that pyroptosis could be induced in autophagy-deficient human trophoblasts treated with sera from PE patients as well as in primary human trophoblasts exposed to hypoxia. Exposure to hypoxia elicits excessive unfolded protein response (UPR) and ER stress and activation of the NOD-like receptor pyrin-containing 3 (NLRP3) inflammasome in primary human trophoblasts. Thioredoxin-interacting protein (TXNIP), a marker for hyperactivated UPR and a crucial signaling molecule linked to NLRP3 inflammasome activation, is significantly increased in hypoxia-treated trophoblasts. No evidence was observed for necroptosis-associated events. Importantly, these molecular events in hypoxia-treated human trophoblasts are significantly observed in placental tissue from women with early onset PE. Taken together, we propose that placental pyroptosis is a key event that induces the release of factors into maternal circulation that possibly contribute to severe sterile inflammation and early onset PE pathology.

Local cerebroplacental ratio reference ranges are better predictors for adverse delivery outcomes in normal weight fetuses during pregnancy

Objective: To evaluate the predictive value of local versus external cerebroplacental ratio (CPR) reference ranges for delivery outcomes in low-risk pregnancies.Methods: A retrospective analysis of all feto-maternal demographic and biometric data in fetuses with normal estimated fetal weight (EFW) and a CPR examination between the years 2014-2019, in a university medical center. The study group included healthy singleton pregnancies from 32-week gestation, with an examination-to-delivery interval of <31 days. The three models compared two thresholds: <5th percentile (CPR 1, CPR 3) and <10th percentile (CPR2). The CPR1 and CPR2 models both use local CPR reference ranges, while the CPR3 model uses an external CPR reference range. The main outcome was predictive accuracy for urgent cesarean delivery (CD), operative delivery (OD), and composite outcome (CO), defined as an Apgar score of <7, fetal blood pH < 7.1 or admission to the neonatal intensive care unit (NICU).Results: Overall, 410 low-risk pregnancies with normal weight fetuses were enrolled in the study. All three CPR models turned out to be significant predictors of CD, with an odds ratio (OR) of 9, 95% CI (2.7-27), p < .001 for CPR1, and an OR of 2.9, 95% CI (1.1-7.4), p < .04 for CPR2, and an OR of 3.4, 95% CI (1.7-6.8), p < .001 for CPR3. All the three models were also found to be predictors of OD, and an OR of 6.9, 95% CI (2.1-22) p < .04 for CPR1, and an OR of 2.8, 95% CI (1.2-6.7), p < .04 for CPR2, and an OR of 2.8, 95% CI (1.4-5.3) p < .01 for CPR3. The positive predictive values (PPV) for CD and OD were both 50% for CPR1, versus 28% and 26% in CPR2, and 24% and 25% in CPR3. The negative predictive value (NPV) was similar, around 88% in all three models. None of the models were found to be significant predictors for CO.Conclusions: A CPR model based on local reference ranges and <5th percentile cutoffs showed the highest PPV for CD and OD. The calculation of local references for CPR should be encouraged.

Synthetic cannabinoids JWH-018, JWH-122, UR-144 and the phytocannabinoid THC activate apoptosis in placental cells

The increasing use of synthetic cannabinoids (SCBs) in recreational settings is becoming a new paradigm of drug abuse. Although SCBs effects mimic those of the Cannabis sativa plant, these drugs are frequently more potent and hazardous. It is known that endocannabinoid signalling plays a crucial role in diverse reproductive events such as placental development. Moreover, the negative impact of the phytocannabinoid Δ⁹-tetrahydrocannabinol (THC) in pregnancy outcome, leading to prematurity, intrauterine growth restriction and low birth weight is well recognized, which makes women of childbearing age a sensitive group to developmental adverse effects of cannabinoids. Placental trophoblast turnover relies on regulated processes of proliferation and apoptosis for normal placental development. Here, we explored the impact of the SCBs JWH-018, JWH-122 and UR-144 and of the phytocannabinoid THC in BeWo cell line, a human placental cytotrophoblast cell model. All the cannabinoids caused a significant decrease in cell viability without LDH release, though this effect was only detected for the highest concentrations of THC. Moreover, a cell cycle arrest at the G₂/M phase was also observed. JWH-018 and JWH-122 increased reactive oxygen species (ROS) production and THC, UR-144 and JWH-122 caused loss of mitochondrial membrane potential. All the compounds were able to induce caspase-9 activation. The involvement of apoptotic pathways was further confirmed through the significant increase in caspase -3/-7 activities. For UR-144, this effect was reversed by the CB1 antagonist AM281, for JWH-018 and THC this effect was mediated by both cannabinoid receptors CB1 and CB2 while for JWH-122 it was cannabinoid receptor-independent. This work demonstrates that THC and SCBs are able to induce apoptotic cell death. Although they may act through different mechanisms and potencies, the studied cannabinoids have the potential to disrupt gestational fundamental events.

Profiles of circular RNAs in human placenta and their potential roles related to preeclampsia

To identify the profiles of circular RNAs (circRNAs) in human placental tissues and to explore the potential roles of dysregulated circRNAs in the pathological genesis of preeclampsia, expression profiles of circRNAs in human placentas were performed in this study. Utilizing high-throughput technology, based on fold changes and P values, 300 circRNAs that are differentially expressed between preeclampsia and normal placental tissues were identified. Among them, hg38_circ_0014736 and hsa_circ_0015382 were validated as significantly upregulated by real-time quantitative PCR with divergent primers. At the same time, hsa_circ_0007121 was significantly downregulated. GO analysis revealed that the three altered circRNAs had a relationship with transcription regulation, proliferation, protein binding, and response to hypoxia. KEGG analysis yielded that apoptosis, Wnt signaling, and HIF-1 pathways were significantly enriched. Interestingly, hsa_circ_0007121 was found to be expressed differently in plasma between preeclampsia and normal pregnancy and this difference could be detected before 20 gestational weeks. Besides, addition receiver operating characteristic (ROC) curve analysis showed that the area under the ROC curve of hsa_circ_0007121 reached 0.72 ([0.59-0.85], P = 0.004) with a sensitivity of 0.77 and specificity of 0.70. Collectively, this study demonstrates the existence of dysregulated circRNAs in the placenta of preeclampsia patients and annotates their potential roles in the pathogenesis of the disease. Encouragingly, hsa_circ_0007121 was found to be a potential noninvasive biomarker for the prediction of preeclampsia.

Pre-eclampsia: pathophysiology and clinical implications

Pre-eclampsia is a common disorder that particularly affects first pregnancies. The clinical presentation is highly variable but hypertension and proteinuria are usually seen. These systemic signs arise from soluble factors released from the placenta as a result of a response to stress of syncytiotrophoblast. There are two sub-types: early and late onset pre-eclampsia, with others almost certainly yet to be identified. Early onset pre-eclampsia arises owing to defective placentation, whilst late onset pre-eclampsia may center around interactions between normal senescence of the placenta and a maternal genetic predisposition to cardiovascular and metabolic disease. The causes, placental and maternal, vary among individuals. Recent research has focused on placental-uterine interactions in early pregnancy. The aim now is to translate these findings into new ways to predict, prevent, and treat pre-eclampsia.

Placental cell death patterns exhibit differences throughout gestation in two strains of laboratory mice

Cell death is an essential physiological process required for the proper development and function of the human placenta. Although the mouse is a commonly used animal model for development studies, little is known about the extent and distribution of cell death in the mouse placenta throughout development and its physiological relevance. In the present study, we report the results of a systematic and quantitative assessment of cell death patterns in the placentae of two strains of laboratory mice commonly used for developmental studies-ICR and C57Bl/6. TUNEL staining revealed that ICR and C57Bl/6 placentae exhibited similar cell death patterns to those reported in human placentae during pregnancy, with comparatively infrequent death observed during early gestation, which increased and became more organized towards term. Interestingly, when comparing strain differences, increased cell death was observed in almost all regions of the inbred C57Bl/6 placentae compared to the outbred ICR strain. Finally, since Bcl-2 ovarian killer (Bok) has been reported to be a key player in human placental cell death, we examined its expression in murine placentae throughout gestation. Bok protein expression was observed in all placental regions and increased towards term in both strains. The results of this study indicate that although strain-specific differences in placental cell death exist, the overall rates and patterns of cell death during murine placentation parallel those previously described in humans. Thus, the murine placenta is a useful model to investigate molecular pathways involved in cell death signaling during human placentation.

MiR-195 modulates oxidative stress-induced apoptosis and mitochondrial energy production in human trophoblasts via flavin adenine dinucleotide-dependent oxidoreductase domain-containing protein 1 and pyruvate dehydrogenase phosphatase regulatory subunit

OBJECTIVE

Preeclampsia is a severe pregnancy-specific syndrome defined as newly onset hypertension and proteinuria. Abnormal placental development has been generally accepted as the initial cause of the disorder. Recently, miR-195 was identified as one of the downregulated small RNAs in preeclamptic placentas.

METHODS

The potential targets of miR-195 in human trophoblast cells were screened by isobaric tags for relative and absolute quantification-based mass spectrum analysis. Localization of miR-195 and its targets was examined by in-situ hybridization and immunohistochemistry in human placenta. Real-time PCR, western blotting and luciferase assay were used for target validation. Apoptosis was accessed by Annexin V/PI costaining, whereas mitochondrial function by ATP measurement and tetramethylrhodamine ethyl ester fluorescence.

RESULTS

Two mitochondria-associated proteins, flavin adenine dinucleotide-dependent oxidoreductase domain-containing protein 1 (FOXRED1) and pyruvate dehydrogenase phosphatase regulatory subunit (PDPR), were identified as targets of miR-195. Overexpression of miR-195 in HTR8/SVneo cells resulted in enhanced apoptosis, decreased mitochondrial membrane potential and cellular ATP content upon hydrogen peroxide stimulation. The effects could be partially rescued by FOXRED1 or PDPR. In preeclamptic patients, lowered circulating level of miR-195 were found at early-to-mid gestation and term pregnancy, and marked increase in FOXRED1 and PDPR expression were observed in the placenta when compared with gestational week-matched controls. In addition, chronic hydrogen peroxide stimuli suppressed miR-195 expression in trophoblast cells.

CONCLUSION

MiR-195 could suppress mitochondrial energy production via targeting FOXRED1 and PDPR, and lead to trophoblast cell apoptosis under oxidative stress. In preeclamptic placenta, lowered level of miR-195 might be induced by chorionic oxidative stress and subsequently form a compensation mechanism to defend the disturbed energy production and cell apoptosis upon oxidative stress.

ANXA4 promotes trophoblast invasion via the PI3K/Akt/eNOS pathway in preeclampsia

The inadequate trophoblast invasion is associated with the development of preeclampsia (PE). Considering that annexin A4 (ANXA4) enhances tumor invasion, we aimed to explore the functional role of ANXA4 in trophoblast cells and to examine the underlying mechanism. ANXA4 expression in PE placentas was analyzed using immunohistochemistry and Western blotting. Cell proliferation, invasion, and apoptosis were determined using a MTT assay, Transwell assay, and flow cytometry, respectively. The expression levels of matrix metalloproteinase (MMP)-2, MMP-9, phosphoinositide 3-kinase (PI3K), Akt, phosphorylated (p)-Akt, and phosphorylated endothelial nitric oxide synthase (p-eNOS) were detected by Western blotting. Placentas were prepared for pathological examination using hematoxylin and eosin staining and apoptosis determination using the TUNEL method. Expression of ANXA4, PI3K, p-Akt and p-eNOS was downregulated in human PE placentas and PE placenta-derived extravillous cytotrophoblasts (EVCTs). Furthermore, ANXA4 overexpression promoted cell proliferation and invasion, inhibited cell apoptosis, and upregulated protein expression of PI3K, p-Akt, and p-eNOS in human trophoblast cells HTR-8/SVneo and JEG-3. By contrast, ANXA4 knockdown exerted the opposite effects. Furthermore, inhibition of the PI3K/Akt pathway by LY294002 abrogated the ANXA4 overexpression-mediated effects on trophoblast behavior. Furthermore, eNOS knockdown abrogated the ANXA4 overexpression-induced promotion of cell invasion and MMP2/9 expression. Additionally, in N-nitro-l-arginine methyl ester (l-NAME)-induced PE rats, ANXA4 overexpression alleviated PE progression, accompanied by an increase in expression of PI3K, p-Akt, and p-eNOS in rat placentas. Our findings demonstrate that ANXA4 expression is downregulated in PE. ANXA4 may promote trophoblast invasion via the PI3K/Akt/eNOS pathway.

The Role of Peroxisome Proliferator–Activated Receptor Gamma (PPARγ) in Mono(2-ethylhexyl) Phthalate (MEHP)-Mediated Cytotrophoblast Differentiation

BACKGROUND

Phthalates are environmental contaminants commonly used as plasticizers in polyvinyl chloride (PVC) products. Recently, exposure to phthalates has been associated with preterm birth, low birth weight, and pregnancy loss. There is limited information about the possible mechanisms linking maternal phthalate exposure and placental development, but one such mechanism may be mediated by peroxisome proliferator–activated receptor γ (PPARγ). PPARγ belongs to the nuclear receptor superfamily that regulates, in a ligand-dependent manner, the transcription of target genes. Studies of PPARγ-deficient mice have demonstrated its essential role in lipid metabolism and placental development. In the human placenta, PPARγ is expressed in the villous cytotrophoblast (VCT) and is activated during its differentiation into syncytiotrophoblast.

OBJECTIVES

The goal of this study was to investigate the action of mono(2-ethylhexyl) phthalate (MEHP) on PPARγ activity during in vitro differentiation of VCTs.

METHODS

We combined immunofluorescence, PPARγ activity/hCG assays, western blotting, and lipidomics analyses to characterize the impacts of physiologically relevant concentrations of MEHP (0.1, 1, and 10 μM) on cultured VCTs isolated from human term placentas.

RESULTS

Doses of 0.1 and 1 μM MEHP showed significantly lower PPARγ activity and less VCT differentiation in comparison with controls, whereas, surprisingly, a 10 μM dose had the opposite effect. MEHP exposure inhibited hCG production and significantly altered lipid composition. In addition, MEHP had significant effects on the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

This study suggests that MEHP has a U-shaped dose–response effect on trophoblast differentiation that is mediated by the PPARγ pathway and acts as an endocrine disruptor in the human placenta. https://doi.org/10.1289/EHP3730.

Involvement of follistatin-like 3 in preeclampsia

INTRODUCTION

Preeclampsia is a main cause of maternal and perinatal mortality and morbidity. The expression of follistatin-like 3 (FSTL3) is enhanced in maternal serum and placenta of preeclamptic women. However, whether FSTL3 is involved in the pathophysiologic of preeclampsia has not been clarified yet.

METHOD

Trophoblast cell lines Swan71 and JAR cells were cultured and siRNA was used to silence FSTL3. The expression of FSTL3 was determined by Western blotting. The matrigel-coated transwell and wound healing assays were used to assess invasion and migration, cell proliferation and apoptosis were detected by CCK-8 and flow cytometric analysis, respectively. Oil red O staining was used to detect the lipid storage in trophoblast.

RESULTS

Hypoxia culture significantly enhanced the expression of FSTL3 by trophoblast. Down-regulation of FSTL3 significantly suppressed the proliferation, migration, invasion and lipid storage but increased apoptosis of trophoblast.

DISCUSSION

Aberrant expression of FSTL3 in preeclampsia led to the dysfunction of trophoblast, indicating its involvement in the pathogenesis of preeclampsia.

QSOX1 regulates trophoblastic apoptosis in preeclampsia through hydrogen peroxide production

Objective: Oxidative stress plays a significant role in the pathogenesis of preeclampsia (PE), by inducing trophoblast cell death and consequent placental dysfunction. Quiescin sulfhydryl oxidase 1 (QSOX1) is upregulated in many types of cancer cells; it promotes disulfide bond formation as well as hydrogen peroxide (H₂O₂) production. The aims of present study are to investigate the expression pattern of QSOX1 in placentae of pregnancies complicated by PE and the role of QSOX1 in the regulation of trophoblastic function, thus providing in-depth understanding of the putative involvement of QSOX1 in the development of PE. Methods: Human term placenta from normal pregnancies and from pregnancies complicated by PE was collected to measure QSOX1 expression and H₂O₂ levels. Down-regulation of QSOX1 in HTR-8/SVneo cells was achieved by siRNA interference. An in vitro cellular PE model was generated by hypoxic incubation. Protein expression levels were assessed by Western blotting, and H₂O₂ levels were determined in the cell culture medium as well as in the cell lysate. Trophoblast apoptosis was evaluated by TUNEL staining. Results: QSOX1 was overexpressed in the PE placenta. Inhibition of QSOX1 expression in HTR-8/SVneo cells attenuated cell apoptosis and intracellular H₂O₂ levels. Hypoxia-induced QSOX1 expression in HTR-8/SVneo cells and led to apoptosis of HTR-8/SVneo cells, and knock-down of QSOX1 rescued hypoxia-induced trophoblast apoptosis. Conclusions: Hypoxia-induced upregulation of QSOX1 and a consequent elevation in intracellular H₂O₂ increased apoptosis in placentae of pregnancies complicated by PE.