Hydroxychloroquine improves pregnancy outcomes by inhibiting excessive autophagy in extravillous trophoblast caused by an anti-phospholipid syndrome

OBJECTIVES

This study aims to investigate the mechanism of hydroxychloroquine (HCQ) immunoregulation therapy in improving adverse pregnancy outcomes of recurrent miscarriages (RM) caused by antiphospholipid syndrome (APS).

METHODS

(i) Immunofluorescence staining was used to analyse the potential targets of antiphospholipid antibodies at the maternal-fetal interface in normal early pregnancy; (ii) Immunohistochemical and immunofluorescence techniques were used to compare and analyse the placenta vascular remodeling, villus tissue synthetic secretion function, trophoblastic autophagy and apoptosis levels in first trimester decidual tissue between normal and APS caused recurrent miscarriages (APS-RM) cases; (iii) HTR8/SVneo and BeWo cell lines were treated with serum from normal and APS-RM cases, and quantified by RT-PCR and Western blot to analysis the expression levels of cell invasion, secretion, autophagy and apoptosis-related molecules; (iv) After adding 0.1 μg/ml HCQ to the serum-treated cell line, the expression of autophagy and invasion-related proteins were detected, and invasion and tube formation of HTR8/SVneo cells was assessed by transwell experiments and tube formation assay.

RESULTS

(i)β2-glycoprotein Ⅰ antigen is expressed in all types of trophoblasts at the maternal-fetal interface in first trimester; (ii) The extravillous trophoblast cells (EVTs) have excessive autophagy in the decidual tissue of the APS-RM cases, and the uterine spiral artery was remodelled insufficiently; (iii) APS-RM cases serum can lead to cell excessive autophagy, and decrease cell invasion and tube formation in vitro; (iv) 0.1 μg/ml HCQ could rescue abnormal cell status caused by APS cases serum in HTR8/SVneo cells in vitro; (v) APS cases serum mainly affects the invasion and tube formation of EVTs, but has little effect on the function of villous trophoblast cells.

CONCLUSIONS

Antiphospholipid antibodies can lead to excessive autophagy in EVTs, thereby affecting ability of invasion and remodeling of spiral arteries, which is one of the mechanisms leading to adverse pregnancy outcomes. HCQ can rescue adverse pregnancy outcomes in APS patients by inhibiting excessive autophagy.

Angiopoietin-2 regulates the phenotypic switch of vascular smooth muscle cells

During uterine spiral artery remodeling, vascular smooth muscle cells (VSMCs) become disorganized and undergo phenotypic switching from a contractile to a more synthetic phenotype. We have previously reported that uterine natural killer cells induce this VSMC phenotypic switching by secreting angiopoietin-2 (Ang-2). Here, we identified the specific mechanisms by which Ang-2 plays a role in this phenomenon. VSMCs isolated from human umbilical arteries were used as an in vitro model to investigate the role of Ang-2 in phenotypic switching. Human decidua tissue from preeclamptic and control pregnancies was collected to compare the expression levels of related proteins. Ang-2 induced a more synthetic phenotype in VSMCs as evidenced by decreased contractile marker expression, increased proliferation and migration, and an altered cytoskeleton. VSMC expressed integrin β6 interacted directly with Ang-2 and induced phosphorylation of FAK (S910 and Y397), AKT (S473), and mTOR (S2448). Knockdown of FAK recovered the calponin loss induced by Ang-2 and resulted in lower EZH2 abundance. Inhibition of FAK and EZH2 both attenuated Ang-2-induced inhibition of the LC3 II/LC3 I ratio and ATG7 expression, and proliferation. Lipid peroxidation inhibition by ferrostatin-1 or the IL-8 receptor antagonist navarixin inhibited the Ang-2-induced migration. IL-8 secretion was significantly lower with lipid peroxidation inhibition. In preeclamptic decidua, there were more unremodeled spiral arteries, and the abundance of Ang-2 was dysregulated. Ang-2 dysregulation may disrupt spiral artery remodeling and contribute to preeclampsia. Ang-2 may be a novel therapeutic target for the treatment of pregnancy complications affected by incomplete spiral artery remodeling.

Role of Decidual Natural Killer Cells in the Pathogenesis of Preeclampsia

Preeclampsia is one of the most severe obstetric complications, yet its pathogenesis remains unclear. Decidual natural killer (dNK) cells, the most abundant immune cells at the maternal-fetal interface, are closely associated with preeclampsia due to abnormalities in their quantity, phenotype, and function. This review summarizes the molecular mechanisms by which dNK cells regulate extravillous trophoblast (EVT) invasion, promote uterine spiral artery remodeling, and maintain immune tolerance. Furthermore, it explores how disruptions in these mechanisms and changes in the decidual microenvironment alter dNK cell properties, driving the progression of preeclampsia. Understanding the mechanisms of dNK cells and identifying potential therapeutic targets may provide new insights for clinical intervention.

Inhibition of NFAT promotes loss of tissue resident uterine natural killer cells and attendant pregnancy complications in humans

Uterine natural killer cells (uNKs) are a tissue resident lymphocyte population that are critical for pregnancy success. Although mouse models have demonstrated that NK deficiency results in abnormal placentation and poor pregnancy outcomes, the generalizability of this knowledge to humans remains unclear. Here we identify uterus transplant (UTx) recipients as a human population with reduced uNK cells and altered pregnancy phenotypes. We show that the NK reduction in UTx correlates with impaired transcriptional programming of NK tissue residency arising from the inhibition of NFAT-mediated signaling. Our observations suggest that NFAT-dependent genes modulate multiple molecular tissue residency programs in uNKs. These include early residency programs involving AP-1-family transcription factors and TGF-β-mediated upregulation of surface integrins. Collectively, our data identify a previously undescribed role for NFAT in uterine NK tissue residency and provide novel mechanistic insights into the biologic basis of pregnancy complications due to alteration of tissue resident NK subsets in humans.

One Sentence Summary

Role of NFAT in uterine NK cell tissue residency.

Endothelial progenitor cells control remodeling of uterine spiral arteries for the establishment of utero-placental circulation

Placental ischemia, resulting from inadequate remodeling of uterine spiral arteries, is a factor in the development of preeclampsia. However, the effect of endothelial progenitor cells that play a role in the vascular injury-repair program is largely unexplored during remodeling. Here, we observe that preeclampsia-afflicted uterine spiral arteries transition to a synthetic phenotype in vascular smooth muscle cells and characterize the regulatory axis in endothelial progenitor cells during remodeling in human decidua basalis. Excessive sEng, secreted by AMP-activated protein kinase (AMPK)-deficient endothelial progenitor cells through the inhibition of HO-1, damages residual endothelium and leads to the accumulation of extracellular matrix produced by vascular smooth muscle cells during remodeling, which is further confirmed by animal models. Collectively, our findings suggest that the impaired functionality of endothelial progenitor cells contributes to the narrowing of remodeled uterine spiral arteries, leading to reduced utero-placental perfusion. This mechanism holds promise in elucidating the pathogenesis of preeclampsia.

Early spiral arteriole remodeling in the uterine-placental interface: A rat model

The mammalian placenta's interface with the parent is a richly vascularized tissue whose development relies upon communication between many different cell types within the uterine microenvironment. The uterine blood vessels of the interface are reshaped during pregnancy into wide-bore, flaccid vessels that convey parental blood to the exchange region of the placenta. Invasive trophoblast as well as parental uterine macrophages and Natural Killer cells are involved in the stepwise remodeling of these vessels and their respective contributions to this crucial process are still being delineated. However, the earliest steps in arteriole remodeling are understudied as they are difficult to study in humans, and other species lack the deep trophoblast invasion that is so prominent a feature of placentation in humans. Here, we further characterize the rat, with deep hemochorial placentation akin to humans, as a model system in which to tease apart the earliest, relatively understudied events in spiral arteriole remodeling. We show that the rat uterine-placental interface increases in size and vascularity rapidly, before trophoblast invasion. The remodeling stages in the arterioles of the rat uterine-placental interface follow a sequence of anatomical changes similar to those in humans, and there are changes to the arterioles' muscular tunica media prior to the marked influx of immune cells. The rat is a tractable model in which to better understand the cell/cell interactions occurring in vivo in an intact tissue microenvironment over time.

Identification of the role of DAB2 and CXCL8 in uterine spiral artery remodeling in early-onset preeclampsia

Aberrant remodeling of uterine spiral arteries (SPA) is strongly associated with the pathogenesis of early-onset preeclampsia (EOPE). However, the complexities of SPA transformation remain inadequately understood. We conducted a single-cell RNA sequencing analysis of whole placental tissues derived from patients with EOPE and their corresponding controls, identified DAB2 as a key gene of interest and explored the mechanism underlying the communication between Extravillous trophoblast cells (EVTs) and decidual vascular smooth muscle cells (dVSMC) through cell models and a placenta-decidua coculture (PDC) model in vitro. DAB2 enhanced the motility and viability of HTR-8/SVneo cells. After exposure to conditioned medium (CM) from HTR-8/SVneoshNC cells, hVSMCs exhibited a rounded morphology, indicative of dedifferentiation, while CM-HTR-8/SVneoshDAB2 cells displayed a spindle-like morphology. Furthermore, the PDC model demonstrated that CM-HTR-8/SVneoshDAB2 was less conducive to vascular remodeling. Further in-depth mechanistic investigations revealed that C-X-C motif chemokine ligand 8 (CXCL8, also known as IL8) is a pivotal regulator governing the dedifferentiation of dVSMC. DAB2 expression in EVTs is critical for orchestrating the phenotypic transition and motility of dVSMC. These processes may be intricately linked to the CXCL8/PI3K/AKT pathway, underscoring its central role in intricate SPA remodeling.

Exploring Natural Killer Cell Testing in Embryo Implantation and Reproductive Failure: An Overview of Techniques and Controversies

The blastocyst nidation is the most crucial stage to a successful pregnancy, as the white cells work to promote a favorable endometrial microenvironment for this process. Intriguingly, this implantation window lasts, on average, 6 days in most regular women, and its quality is affected by many pathological conditions. Since the grounds of reproductive failure in healthy couples are still uncharted, studies have widely suggested a potential hostile role of the immune system in the equilibrium of the maternal-fetal interface. In recent years, natural killer cells have been the highlight as they represent the greatest lymphocyte in the uterus and have immune surveillance through cytotoxicity during the implantation window. This review explored the main techniques used for natural killer (NK) cell testing in the implantation window over the last 13 years on the PubMed® database. Of 2167 published articles potentially relevant for the review, only thirty-three were about cell evaluation in healthy women, met the inclusion criteria, and had their methodology critically analyzed. Here, we bring a summary from the study group and sample collection to evidence comments about their findings and correlations. Meanwhile, we also summarize the current relationship between NK cells and endometrial receptivity with reproductive failure to help enhance the possibilities for future research. In conclusion, our overview points out that restricted and unstandardized methods support the controversy between the NK population and unsuccessful embryo implantation, which is an obstacle to studying why healthy eggs do not thrive and finding a solution for one of the most controversial topics in human reproduction.

Changes in Immune Response during Pig Gestation with a Focus on Cytokines

Pigs have the highest percentage of embryonic death not associated with specific diseases of all livestock species, at 20-45%. During gestation processes, a series of complex alterations can arise, including embryonic migration and elongation, maternal immunological recognition of pregnancy, and embryonic competition for implantation sites and subsequent nutrition requirements and development. Immune cells and cytokines act as mediators between other molecules in highly complex interactions between various cell types. However, other non-immune cells, such as trophoblast cells, are important in immune pregnancy regulation. Numerous studies have shed light on the crucial roles of several cytokines that regulate the inflammatory processes that characterize the interface between the fetus and the mother throughout normal porcine gestation, but most of these reports are limited to the implantational and peri-implantational periods. Increase in some proinflammatory cytokines have been found in other gestational periods, such as placental remodeling. Porcine immune changes during delivery have not been studied as deeply as in other species. This review details some of the immune system cells actively involved in the fetomaternal interface during porcine gestation, as well as the principal cells, cytokines, and molecules, such as antibodies, that play crucial roles in sow pregnancy, both in early and mid-to-late gestation.

Endometrial BMP2 Deficiency Impairs ITGB3-Mediated Trophoblast Invasion in Women With Repeated Implantation Failure

BACKGROUND

Repeated implantation failure (RIF) leads to a waste of high-quality embryos and remains a challenge in assisted reproductive technology. During early human placentation, the invasion of trophoblast cells into the decidua is an essential step for the establishment of maternal-fetal interactions and subsequent successful pregnancy. Bone morphogenetic protein 2 (BMP2) has been reported to regulate endometrial receptivity and promote trophoblast invasion. However, whether there is dysregulation of endometrial BMP2 expression in patients with RIF remains unknown. Additionally, the molecular mechanisms underlying the effects of BMP2 on human trophoblast invasion and early placentation remain to be further elucidated.

METHODS

Midluteal phase endometrial samples were biopsied from patients with RIF and from routine control in vitro fertilization followed by quantitative polymerase chain reaction and immunoblotting analyses. Human trophoblast organoids, primary human trophoblast cells, and an immortalized trophoblast cell line (HTR8/SVneo) were used as study models.

RESULTS

We found that BMP2 was aberrantly low in midluteal phase endometrial tissues from patients with RIF. Recombinant human BMP2 treatment upregulated integrin β3 (ITGB3) in a SMAD2/3-SMAD4 signaling-dependent manner in both HTR8/SVneo cells and primary trophoblast cells. siRNA-mediated integrin β3 downregulation reduced both basal and BMP2-upregulated trophoblast invasion and vascular mimicry in HTR8/SVneo cells. Importantly, shRNA-mediated ITGB3 knockdown significantly decreased the formation ability of human trophoblast organoids.

CONCLUSION

Our results demonstrate endometrial BMP2 deficiency in patients with RIF. ITGB3 mediates both basal and BMP2-promoted human trophoblast invasion and is essential for early placentation. These findings broaden our knowledge regarding the regulation of early placentation and provide candidate diagnostic and therapeutic targets for RIF clinical management.

Defective Uterine Spiral Artery Remodeling and Placental Senescence in a Pregnant Rat Model of Polycystic Ovary Syndrome

Pregnancy-related problems have been linked to impairments in maternal uterine spiral artery (SpA) remodeling. The mechanisms underlying this association are still unclear. It is also unclear whether hyperandrogenism and insulin resistance, the two common manifestations of polycystic ovary syndrome, affect uterine SpA remodeling. We verified previous work in which exposure to 5-dihydrotestosterone (DHT) and insulin (INS) in rats during pregnancy resulted in hyperandrogenism, insulin intolerance, and higher fetal mortality. Exposure to DHT and INS dysregulated the expression of angiogenesis-related genes in the uterus and placenta and also decreased expression of endothelial nitric oxide synthase and matrix metallopeptidases 2 and 9, increased fibrotic collagen deposits in the uterus, and reduced expression of marker genes for SpA-associated trophoblast giant cells. These changes were related to a greater proportion of unremodeled uterine SpAs and a smaller proportion of highly remodeled arteries in DHT + INS-exposed rats. Placentas from DHT + INS-exposed rats exhibited decreased basal and labyrinth zone regions, reduced maternal blood spaces, diminished labyrinth vascularity, and an imbalance in the abundance of vascular and smooth muscle proteins. Furthermore, placentas from DHT + INS-exposed rats showed expression of placental insufficiency markers and a significant increase in cell senescence-associated protein levels. Altogether, this work demonstrates that increased pregnancy complications in polycystic ovary syndrome may be mediated by problems with uterine SpA remodeling, placental functionality, and placental senescence.

Endometrial TGFβ signaling fosters early pregnancy development by remodeling the fetomaternal interface

The endometrium is a unique and highly regenerative tissue with crucial roles during the reproductive lifespan of a woman. As the first site of contact between mother and embryo, the endometrium, and its critical processes of decidualization and immune cell recruitment, play a leading role in the establishment of pregnancy, embryonic development, and reproductive capacity. These integral processes are achieved by the concerted actions of steroid hormones and a myriad of growth factor signaling pathways. This review focuses on the roles of the transforming growth factor β (TGFβ) pathway in the endometrium during the earliest stages of pregnancy through the lens of immune cell regulation and function. We discuss how key ligands in the TGFβ family signal through downstream SMAD transcription factors and ultimately remodel the endometrium into a state suitable for embryo implantation and development. We also focus on the key roles of the TGFβ signaling pathway in recruiting uterine natural killer cells and their collective remodeling of the decidua and spiral arteries. By providing key details about immune cell populations and TGFβ signaling within the endometrium, it is our goal to shed light on the intricate remodeling that is required to achieve a successful pregnancy.

Unraveling the mysteries of spiral artery remodeling

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

The function of decidua natural killer cells in physiology and pathology of pregnancy

The role of decidual natural killer (dNK) cells in maintaining immune tolerance at the maternal-fetal interface during pregnancy is a significant topic in reproductive health. Immune tolerance is essential for a successful pregnancy and involves a complex immune response involving various immune cells and molecules. DNK cells comprise the largest population of lymphocyte subsets found in the decidua and play important roles in maintaining immune tolerance. These cells exert multiple functions to maintain homeostasis of the decidual microenvironment, including modulation of trophoblast invasion, promotion of fetal development, regulation of endometrial decidualization and spiral artery remodeling. DNK cells can also be divided into different subsets based on their functions as NKtolerant , NKcytotoxic , and NKregulatory cells. However, the relationship between dNK cells function and pregnancy outcomes is complex and poorly understood. In this review, we will focus on the physiological role of dNK cells during pregnancy and highlight the potential role in pathological pregnancies and therapeutic approaches.

Three-Dimensional Histological Characterization of the Placental Vasculature Using Light Sheet Microscopy

The placenta is the first embryonic organ, representing the connection between the embryo and the mother, and is therefore necessary for the embryo's growth and survival. To meet the ever-growing need for nutrient and gas exchange, the maternal spiral arteries undergo extensive remodeling, thus increasing the uteroplacental blood flow by 16-fold. However, the insufficient remodeling of the spiral arteries can lead to severe pregnancy-associated disorders, including but not limited to pre-eclampsia. Insufficient endovascular trophoblast invasion plays a key role in the manifestation of pre-eclampsia; however, the underlying processes are complex and still unknown. Classical histopathology is based on two-dimensional section microscopy, which lacks a volumetric representation of the vascular remodeling process. To further characterize the uteroplacental vascularization, a detailed, non-destructive, and subcellular visualization is beneficial. In this study, we use light sheet microscopy for optical sectioning, thus establishing a method to obtain a three-dimensional visualization of the vascular system in the placenta. By introducing a volumetric visualization method of the placenta, we could establish a powerful tool to deeply investigate the heterogeneity of the spiral arteries during the remodeling process, evaluate the state-of-the-art treatment options, effects on vascularization, and, ultimately, reveal new insights into the underlying pathology of pre-eclampsia.

Conventional natural killer cells control vascular remodeling in the uterus during pregnancy by acidifying the extracellular matrix with a2V

Vascular remodeling within the uterus immediately before and during early pregnancy increases blood flow in the fetus and prevents the development of gestational hypertension. Tissue-resident natural killer (trNK) cells secrete pro-angiogenic growth factors but are insufficient for uterine artery (UtA) remodeling in the absence of conventional natural killer (cNK) cells. Matrix metalloproteinase-9 (MMP9) is activated in acidic environments to promote UtA remodeling. We have previously shown that ATPase a2V plays a role in regulating the function of cNK cells during pregnancy. We studied the effect of a2V deletion on uterine cNK cell populations and pregnancy outcomes in VavCrea2Vfl/fl mice, where a2V is conditionally deleted in hematopoietic stem cells. Conventional NKcells were reduced but trNK cells were retained in implantation sites at gestational day 9.5, and UtA remodeling was inhibited despite no differences in concentrations of pro-angiogenic growth factors. The ratio of pro-MMP9 to total was significantly elevated in VavCrea2Vfl/fl mice, and MMP9 activity was significantly reduced. The pH of implantation sites was significantly elevated in VavCrea2Vfl/fl mice. We concluded that the role of cNK cells in the uterus is to acidify the extracellular matrix (ECM) using a2V, which activates MMP9 to degrade the ECM, release bound pro-angiogenic growth factors, and contribute to UtA remodeling. Our results are significant for the understanding of the development of gestational hypertension.

Global trends in research of immune cells associated with hypertensive disorders of pregnancy: A 20-year bibliometric analyses (from 2001 to 2021)

Background

A growing evidence suggests that immune cells play a significant role in the pathogenesis of hypertensive disorders of pregnancy (HDP).Over the past 20 years, several studies have been conducted on the role of immune cells in hypertensive disorders of pregnancy. This study used bibliometric analysis to assess research hotspots and future trends in studies on immune cells in hypertensive disorders of pregnancy.

Methods

We extracted all relevant literature on immune cells and hypertensive disorders of pregnancy from the Web of Science core collection for the period of 2001 to 2021. We used VOS Viewer, CiteSpace, R-bibliometrix and Python for bibliometric analysis.

Results

We identified 2,388 records published in 593 journals by 9,886 authors from 2,174 universities/institutions in 91 countries/regions. The number of publications tended to increase over time, with the highest number of publications in 2021, up to 205. The USA was the country with the most publications. UNIVERSITY OF MISSISSIPPI was the most influential institution. Lamarca B, Romero R, and Saito S were the most prolific authors. Finally, three research hotspot clusters were identified based on keywords, which reflected the role of immune cells in the development of hypertensive disorders of pregnancy, the current research status,and predicted hot spots for future research.

Conclusions

Our study systematically analyzed the role of immune cells in the pathogenesis of hypertensive disorders of pregnancy in the last 20 years. Our results indicated that immune cells, such as T cells, natural killer (NK) cells,and macrophages, and the cytokines released such as TNF-α, IFN-γ in the maternal circulation and at the maternal-fetal interface would influence the development of hypertensive disorders of pregnancy and we need further investigate the role of individual immune cells and translational studies to provide new therapeutic perspectives to mitigate adverse perinatal outcomes due to hypertensive disorders of pregnancy. In conclusion, bibliometric studies provide a general overview of immune cells in the study of hypertensive disorders of pregnancy.

PVT1/miR-145-5p/HK2 modulates vascular smooth muscle cells phenotype switch via glycolysis: The new perspective on the spiral artery remodeling

INTRODUCTION

Vascular smooth muscle cells (VSMC) switched from a contractile phenotype to a synthetic phenotype during the decidual spiral artery (SPAs) remodeling process. The lncRNA plasmacytoma variant translocation 1 (PVT1) and glucose metabolism have been found to regulate the VSMC phenotype switch. This study aimed to analyze the dynamic expression of PVT1 and glycolytic key enzymes hexokinase2 (HK2) at different remodeling stages in early human pregnancy and elucidate the underlying mechanism of the PVT1/miR-145-5p/HK2 axis involved in the spiral artery remodeling.

METHODS

qRT-PCR, Western blot (WB) analysis, Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were used to detect the expression and localization of PVT1 and HK2 in decidual tissue. HA-VSMCs were transfected with specific siRNA, shRNA and plasmids to regulate corresponding genes. Extracellular lactate, cellular ATP, ROS, and intracellular NADPH levels were measured using the corresponding assay kits. Migration was measured by wound-healing and Transwell assays. Contractile phenotypic markers α-SMA, MYH11 with calponin and synthetic phenotypic markers OPN and vimentin were detected by WB. The PDC model was used to detect the degree of spiral arterial remodeling.

RESULTS

PVT1 and HK2 were upregulated with gestational age (GA) increasing in decidual tissue during the early pregnancy. HK2 regulated the glycolytic activity and VSMC phenotype switch in vitro. PVT1 regulated the glycolytic activity and VSMC phenotype switch through HK2. PVT1 played a ceRNA role in regulating HK2 expression by sponging miR-145-5p. PVT1 and HK2 influenced spiral artery remodeling in the PDC model.

DISCUSSION

PVT1 and HK2 were upregulated, and miR-145-5p was downregulated in decidua with the GA increasing. Meanwhile, the PVT1/miR-145-5p/HK2 axis may be involved in regulating the phenotypic switch and migratory capacity of VSMCs by affecting glycolysis in decidual SPAs remodeling.

Human placental development and function

The placenta is a transient fetal organ that plays a critical role in the health and wellbeing of both the fetus and its mother. Functionally, the placenta sustains the growth of the fetus as it facilitates delivery of oxygen and nutrients and removal of waste products. Not surprisingly, defective early placental development is the primary cause of common disorders of pregnancy, including recurrent miscarriage, fetal growth restriction, pre-eclampsia and stillbirth. Adverse pregnancy conditions will also affect the life-long health of the fetus via developmental programming[1]. Despite its critical importance in reproductive success and life-long health, our understanding of placental development is not extensive, largely due to ethical limitations to studying early or chronological placental development, lack of long-term in vitro models, or comparative animal models. In this review, we examine current knowledge of early human placental development, discuss the critical role of the maternal endometrium and of the fetal-maternal dialogue in pregnancy success, and we explore the latest models of trophoblast and endometrial stem cells. In addition, we discuss the role of oxygen in placental formation and function, how nutrient delivery is mediated during the periods of histotrophic nutrition (uptake of uterine secretions) and haemotrophic nutrition (exchange between the maternal and fetal circulations), and how placental endocrine function facilitates fetal growth and development.

Porphyromonas gingivalis-mediated disruption in spiral artery remodeling is associated with altered uterine NK cell populations and dysregulated IL-18 and Htra1

Impaired spiral artery remodeling (IRSA) underpins the great obstetrical syndromes. We previously demonstrated that intrauterine infection with the periodontal pathogen, Porphyromonas gingivalis, induces IRSA in rats. Since our previous studies only examined the end stage of arterial remodeling, the aim of this study was to identify the impact of P. gingivalis infection on the earlier stages of remodeling. Gestation day (GD) 11 specimens, a transition point between trophoblast-independent remodeling and the start of extravillous trophoblast invasion, were compared to late stage GD18 tissues. P. gingivalis was found in decidual stroma of GD11 specimens that already had reduced spiral artery remodeling defined as smaller arterial lumen size, increased retention of vascular smooth muscle, and decreased invasion by extravillous trophoblasts. At GD11, P. gingivalis-induced IRSA coincided with altered uterine natural killer (uNK) cell populations, decreased placental bed expression of interleukin-18 (IL-18) with increased production of temperature requirement A1 (Htra1), a marker of oxidative stress. By GD18, placental bed IL-18 and Htra1 levels, and uNK cell numbers were equivalent in control and infected groups. However, infected GD18 placental bed specimens had decreased TNF + T cells. These results suggest disturbances in placental bed decidual stroma and uNK cells are involved in P. gingivalis-mediated IRSA.

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

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

Role of osteopontin (OPN) in uterine spiral artery remodeling

Uterine spiral artery (SpA) remodeling is critical for a successful pregnancy. The deficiency of SpA remodeling seriously affects the blood perfusion of the placenta, impacting the nutritional supply to the fetus and therefore fetal growth and development, which is one of the pathological causes of pregnancy related diseases. This process involves the interaction between all cells and related factors at the maternal-fetal interface, especially extravillous trophoblast cells (EVT), vascular smooth muscle cells (VSMCs) and decidual immune cells. Osteopontin (OPN), as a glycosylated protein, is widely localized in the extracellular matrix and participates in a variety of cellular activities such as migration, adhesion, differentiation and survival. OPN plays an important role in placental development, uterine decidualization and pregnancy success. This study focuses on the role of OPN in uterine spiral artery remodeling and its related molecular mechanism.

Uterine Natural Killer Cells: A Rising Star in Human Pregnancy Regulation

Uterine natural killer (uNK) cells are an immune subset located in the uterus. uNK cells have distinct tissue-specific characteristics compared to their counterparts in peripheral blood and lymphoid organs. Based on their location and the pregnancy status of the host, uNK cells are classified as endometrial NK (eNK) cells or decidua NK (dNK) cells. uNK cells are important in protecting the host from pathogen invasion and contribute to a series of physiological processes that affect successful pregnancy, including uterine spiral artery remodeling, fetal development, and immunity tolerance. Abnormal alterations in uNK cell numbers and/or impaired function may cause pregnancy complications, such as recurrent miscarriage, preeclampsia, or even infertility. In this review, we introduce recent advances in human uNK cell research under normal physiological or pathological conditions, and summarize their unique influences on the process of pregnancy complications or uterine diseases. Finally, we propose the potential clinical use of uNK cells as a novel cellular immunotherapeutic approach for reproductive disorders.

The mystery of the life tree: the placenta

The placenta is the interface between the fetal and maternal environments during mammalian gestation, critically safeguarding the health of the developing fetus and the mother. Placental trophoblasts origin from embryonic trophectoderm that differentiates into various trophoblastic subtypes through villous and extravillous pathways. The trophoblasts actively interact with multiple decidual cells and immune cells at the maternal-fetal interface and thus construct fundamental functional units, which are responsible for blood perfusion, maternal-fetal material exchange, placental endocrine, immune tolerance, and adequate defense barrier against pathogen infection. Various pregnant complications are tightly associated with the defects in placental development and function maintenance. In this review, we summarize the current views and our recent progress on the mechanisms underlying the formation of placental functional units, the interactions among trophoblasts and various uterine cells, as well as the placental barrier against pathogen infections during pregnancy. The involvement of placental dysregulation in adverse pregnancy outcomes is discussed.

Uterine NK cell functions at maternal-fetal interface

During pregnancy, maternal decidual tissue interacts with fetal trophoblasts. They constitute the maternal-fetal interface responsible for supplying nutrition to the fetus. Uterine natural killer (uNK) cells are the most abundant immune cells at the maternal-fetal interface during early pregnancy and play critical roles throughout pregnancy. This review provides current knowledge about the functions of uNK cells. uNK cells have been shown to facilitate remodeling of the spiral artery, control the invasion of extravillous trophoblast (EVT) cells, contribute to the induction and maintenance of immune tolerance, protect against pathogen infection, and promote fetal development. Pregnancy-trained memory of uNK cells improves subsequent pregnancy outcomes. In addition, this review describes the distinct functions of three uNK cell subsets: CD27-CD11b-, CD27+ and CD27-CD11b+ uNK cells.

Insights into Early-Pregnancy Mechanisms: Mast Cells and Chymase CMA1 Shape the Phenotype and Modulate the Functionality of Human Trophoblast Cells, Vascular Smooth-Muscle Cells and Endothelial Cells

Spiral-artery (SA) remodeling is a fundamental process during pregnancy that involves the action of cells of the initial vessel, such as vascular smooth-muscle cells (VSMCs) and endothelial cells, but also maternal immune cells and fetal extravillous trophoblast cells (EVTs). Mast cells (MCs), and specifically chymase-expressing cells, have been identified as key to a sufficient SA-remodeling process in vivo. However, the mechanisms are still unclear. The purpose of this study is to evaluate the effects of the MC line HMC-1 and recombinant human chymase (rhuCMA1) on human primary uterine vascular smooth-muscle cells (HUtSMCs), a human trophoblast cell line (HTR8/SV-neo), and human umbilical-vein endothelial cells (HUVEC) in vitro. Both HMC-1 and rhuCMA1 stimulated migration, proliferation, and changed protein expression in HUtSMCs. HMC-1 increased proliferation, migration, and changed gene expression of HTR8/SVneo cells, while rhuCMA treatment led to increased migration and decreased expression of tissue inhibitors of matrix metalloproteinases. Additionally, rhuCMA1 enhanced endothelial-cell-tube formation. Collectively, we identified possible mechanisms by which MCs/rhuCMA1 promote SA remodeling. Our findings are relevant to the understanding of this crucial step in pregnancy and thus of the dysregulated pathways that can lead to pregnancy complications such as fetal growth restriction and preeclampsia.

Uterine Natural Killer Cells and Implantation

Decidual leukocytes make up approximately 30% of all decidual stromal cells in early pregnancy, of which 70% are uterine natural killer (uNK) cells. uNK cells are phenotypically distinct from peripheral blood NK cells, being CD56[Formula: see text]CD16[Formula: see text]. A recent single-cell sequencing project of the decidua identified three subsets of uNK cells, but we are yet to determine how they differ functionally. Several roles for uNK cells in implantation are starting to emerge including biosensing of poor-quality embryos, killing of bacteria infected trophoblast, spiral artery remodeling, and regulation of trophoblast invasion. Altered numbers of uNK cells have been identified in several pathological conditions, but whether this is causative of the condition is currently unclear.

From stem cells to spiral arteries: A journey through early placental development

Early placental development lays the foundation of a healthy pregnancy, and numerous tightly regulated processes must occur for the placenta to meet the increasing nutrient and oxygen exchange requirements of the growing fetus later in gestation. Inadequacies in early placental development can result in disorders such as fetal growth restriction that do not present clinically until the second half of gestation. Indeed, growth restricted placentae exhibit impaired placental development and function, including reduced overall placental size, decreased branching of villi and the blood vessels within them, altered trophoblast function, and impaired uterine vascular remodelling, which together combine to reduce placental exchange capacity. This review explores the importance of early placental development across multiple anatomical aspects of placentation, from the stem cells and lineage hierarchies from which villous core cells and trophoblasts arise, through extravillous trophoblast invasion and spiral artery remodelling, and finally remodelling of the larger uterine vessels.

miRNAs in decidual NK cells: regulators worthy of attention during pregnancy

The critical immune effectors, including T, B, and natural killer (NK) cells, dendritic cells, and macrophages participate in regulating immune responses during pregnancy. Among these immune cells, decidual NK (dNK) cells are involved in key placental development processes at the maternal-fetal interface, such as uterine spiral artery remodeling, trophoblast invasion, and decidualization. Mechanistically, dNK cells significantly influence pregnancy outcome by secreting cytokines, chemokines, and angiogenic mediators and by their interactions with trophoblasts and other decidual cells. MicroRNAs (miRNAs) are small non-coding RNA molecules that participate in the initiation and progression of human diseases. Although the functions of circulating miRNAs in pathological mechanism has been extensively studied, the regulatory roles of miRNAs in NK cells, especially in dNK cells, have been rarely reported. In this review, we analyze the effects of miRNA regulations of dNK cell functions on the immune system during gestation. We discuss aberrant expressions of certain miRNAs in dNK cells that may lead to pathological consequences, such as recurrent pregnancy loss (RPL). Interestingly, miRNA expression patterns are also different between dNK cells and peripheral NK (pNK) cells, and pNK cells in the first- and third-trimester of gestation. The dysregulation of miRNA plays a pivotal regulatory role in driving immune functions of dNK and pNK cells. Further understanding of the molecular mechanisms of miRNAs in dNK cells may provide new insights into the development of therapeutics to prevent pregnancy failure.

Role of Decidual Natural Killer Cells in Human Pregnancy and Related Pregnancy Complications

Pregnancy is a unique type of immunological process. Healthy pregnancy is associated with a series of inflammatory events: implantation (inflammation), gestation (anti-inflammation), and parturition (inflammation). As the most abundant leukocytes during pregnancy, natural killer (NK) cells are recruited and activated by ovarian hormones and have pivotal roles throughout pregnancy. During the first trimester, NK cells represent up to 50–70% of decidua lymphocytes. Differently from peripheral-blood NK cells, decidual natural killer (dNK) cells are poorly cytolytic, and they release cytokines/chemokines that induce trophoblast invasion, tissue remodeling, embryonic development, and placentation. NK cells can also shift to a cytotoxic identity and carry out immune defense if infected in utero by pathogens. At late gestation, premature activation of NK cells can lead to a breakdown of tolerance of the maternal–fetal interface and, subsequently, can result in preterm birth. This review is focused on the role of dNK cells in normal pregnancy and pathological pregnancy, including preeclampsia, recurrent spontaneous abortion, endometriosis, and recurrent implantation failure. dNK cells could be targets for the treatment of pregnancy complications.

Uterine natural killer cells: from foe to friend in reproduction

BACKGROUND

Recurrent miscarriage and pre-eclampsia are common reproductive disorders, but their causes are often unknown. Recent evidence has provided new insight into immune system influences in reproductive disorders. A subset of lymphocytes of the innate immune system known as uterine natural killer (uNK) cells are now recognized as fundamental to achieving embryo implantation and successful pregnancy, but were initially attributed a bad reputation. Indeed, immune therapies have been developed to treat the 'exaggerated' immune response from uNK cells. These treatments have been based on studies of peripheral blood natural killer (pbNK) cells. However, uNK cells and pbNK cells have different phenotypic and functional characteristics. The functions of uNK cells are closely related to their interactions with the extravillous trophoblast cells (EVTs) and spiral arteries, which underlie an essential role in regulating vascular function, controlling trophoblast invasion and promoting placental development. EVTs express MHC molecules of class I HLA-C/E/G/F, while uNK cells express, among other receptors, killer cell immunoglobulin-like receptors (KIRs) that bind to HLA-C or CD94/NKG2A inhibitory receptors, and then bind HLA-E. Associations of certain KIR/HLA-C combinations with recurrent miscarriage, pre-eclampsia, and foetal growth restriction and the interactions between uNK cells, trophoblasts and vascular cells have led to the hypothesis that uNK cells may play a role in embryo implantation.

OBJECTIVE AND RATIONALE

Our objective was to review the evolution of our understanding of uNK cells, their functions, and their increasingly relevant role in reproduction.

SEARCH METHODS

Relevant literature through June 2020 was retrieved using Google Scholar and PubMed. Search terms comprised uNK cells, human pregnancy, reproductive failure, maternal KIR and HLA-C, HLA-E/G/F in EVT cells, angiogenic cytokines, CD56+ NK cells, spiral artery, oestrogen and progesterone receptors, KIR haplotype and paternal HLA-C2.

OUTCOMES

This review provides key insights into the evolving conceptualization of uNK cells, from their not-so-promising beginnings to now, when they are considered allies in reproduction. We synthesized current knowledge about uNK cells, their involvement in reproduction and their main functions in placental vascular remodeling and trophoblast invasion. One of the issues that this review presents is the enormous complexity involved in studying the immune system in reproduction. The complexity in the immunology of the maternal-foetal interface lies in the great variety of participating molecules, the processes and interactions that occur at different levels (molecular, cellular, tissue, etc.) and the great diversity of genetic combinations that are translated into different types of responses.

WIDER IMPLICATIONS

Insights into uNK cells could offer an important breakthrough for ART outcomes, since each patient could be assessed based on the combination of HLA and its receptors in their uNK cells, evaluating the critical interactions at the materno-foetal interface. However, owing to the technical challenges in studying uNK cells in vivo, there is still much knowledge to gain, particularly regarding their exact origin and functions. New studies using novel molecular and genetic approaches can facilitate the identification of mechanisms by which uNK cells interact with other cells at the materno-foetal interface, perhaps translating this knowledge into clinical applicability.

The role of decidual natural killer cell derived soluble factors in early pregnancy

Decidual natural killer cell (dNK), the predominant decidual lymphocytes in early pregnancy, are primarily identified based on their CD56^bright CD16^- phenotype and play an important role in maintaining immune tolerance at the maternal-fetal interface. dNK dysfunction reportedly leads to pathological pregnancy. Indeed, various dNK-derived soluble factors are involved in a series of key processes related to pregnancy outcomes. In this review, we summarize the roles of these dNK-derived factors in immune tolerance and embryonic development to improve the current understanding regarding the physiological and pathological mechanisms that occur during pregnancy, while potentially informing the development of effective therapeutics.

Association of VEGF and p53 Polymorphisms and Spiral Artery Remodeling in Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis

Many studies have reported the association of VEGF-1154G/A, VEGF 936C/T, and p53 Arg72Pro polymorphisms with recurrent pregnancy loss (RPL), but the outcomes are inconsistent. We have used a meta-analysis to associate these polymorphisms with RPL, having the spiral artery remodeling as a major risk factor. The studies were identified from three different reputed databases, namely ScienceDirect, PubMed/Medline, and Scopus. The eligible studies of VEGF-1154G/A, VEGF 936C/T, and p53Arg72Pro polymorphisms associated with the RPL were selected for the analysis. They were segregated into three different ethnic groups as Asians, Caucasians, and mixed population. For the analysis, the overall prevalence, odds ratio, risk ratio, relative risk ratio, and p-values were calculated. A total of 3,241 RPL cases and 3,205 healthy controls from 21 different case-control studies were analyzed. RPL was highly prevalent in the mixed population with VEGF-1154G/A and p53 Arg72Pro polymorphisms (70.04 and 66.46%, respectively) and in the Asian population with VEGF 936C/T polymorphism (53.58%). The homozygous recessive genotypes of VEGF and p53 exhibited significant association between the respective polymorphisms and RPL along with the increased risk of outcome. The current analysis conclusively reports the geographic distribution of the different genetic polymorphisms which shows high association with the progression of RPL. Understanding the spectrum of polymorphisms on different populations with the spiral artery remodeling as a risk factor encloses the importance of the vasculature during the pregnancy.

Distinct uterine artery gene expression profiles during early gestation in the stroke-prone spontaneously hypertensive rat

During pregnancy, the uterine spiral arteries undergo major vascular remodeling to ensure sufficient uteroplacental perfusion to support the fetus. In pregnancies complicated by hypertensive disorders, this remodeling is deficient leading to impaired uteroplacental blood flow and poor maternal and fetal outcomes. The underlying genetic mechanisms for failed vascular remodeling are not fully understood. This study aimed to examine the early-pregnancy-associated gene changes in the uterine arteries of spontaneously hypertensive stroke-prone rats (SHRSP) compared with their normotensive counterparts, Wistar-Kyoto rats (WKY). Uterine arteries from gestational day 6.5 WKY and SHRSP were processed for RNA-sequencing, along with virgin, age-matched controls for each strain. Gene expression changes were identified and biological pathways were implicated and interpretated using ingenuity pathway analysis (IPA). This study found that WKY uterine arteries from early pregnancy exhibit a gene expression pattern that is suggestive of a pregnancy-dependent reduction in Ca²⁺ handling and renin-angiotensin-aldosterone system (RAAS) components and an increase in ATP production. In contrast, the expression pattern of pregnant SHRSP uterine arteries was dominated by an elevated immune response and increased production of reactive oxygen species (ROS) and downstream effectors of the RAAS. These results suggest that in a rat model, hypertension during pregnancy impacts uterine artery gene expression patterns as early as the first week of pregnancy. The pathway changes involved may underlie or contribute to the adverse vascular remodeling and resultant placental ischemia and systemic vascular dysfunction observed in SHRSP in late gestation.

Steroid hormones and first trimester vascular remodeling

Successful implantation and placentation require neoangiogenesis and the remodeling of the uterine spiral arteries. Progesterone and estradiol control various of the placental functions, but their role in vascular remodeling remains controversial. Therefore, this chapter aims to summarize the current knowledge regarding the role of steroid hormones in the uteroplacental vascular remodeling during the first trimester of gestation.

Angiopoietin 2 stimulates trophoblast invasion via a mechanism associated with JNK signaling

Extravillous trophoblast cell (EVT) invasion is tightly controlled, and its dysregulation can lead to altered spiral artery remodeling and contribute to a number of different pregnancy complications. Angiopoietin-2 (Ang-2) is expressed by trophoblast cells and various cells in the decidua, and trophoblast cells express its receptor, Tie2. Ang-2 has been shown to play roles in tumor progression and metastasis but it is not known if it also regulates EVT invasion. Here, we show that both the HTR-8/SVneo cell line and primary isolates of human EVT expressed various integrins and the Tie2 receptor, and Ang-2 stimulated their migration and/or invasion. Ang-2 increased expression of matrix metalloproteinase (MMP)2 and MMP9, altered the cytoskeleton of HTR-8/SVneo cells and also induced phosphorylation of Tie2, JNK and c-Jun. Inhibition of p-JNK (using SP600125) blocked the Ang-2 induced invasion of HTR-8/SVneo cells. In addition, inhibition of Tie2 (pexmetinib) and integrin signaling (RGDS and ATN-161) also blocked Ang-2-induced invasion. In conclusion, we demonstrate that Ang-2 can stimulate EVT invasion via a mechanism associated with activation of both the Tie2 receptor and integrins, which appear to work through different pathways; Tie2 through the JNK/c-JUN pathway and integrins through an as yet unidentified pathway(s). We therefore propose that any alterations in Ang-2 expression in the decidua would lead to an imbalance in pro- and anti-invasive factors, disrupting regulation of EVT invasion and spiral artery remodeling and thereby contribute to the etiology of several complications of pregnancy.

Pathological investigation of placentas in preeclampsia (the PEARL study)

INTRODUCTION: Preeclampsia (PE), but mainly preterm PE, is associated with deep placentation disorders. We aimed to compare placental pathologies in pregnancies affected by term and preterm PE compared to normal pregnancies. METHODS: We performed a prospective case-cohort study. Low-risk nulliparous women were recruited in the first trimester and women who developed PE were recruited at diagnosis. Placental pathologies were reported according to the Amsterdam Placental Workshop Group Consensus Statement and were compared between cases and controls. PE cases stratified as term (≥37 weeks) and preterm PE (<37 weeks). Our primary outcome was maternal vascular malperfusion (MVM). RESULTS: Twenty-four women who developed preterm PE were compared to 10 women who developed term PE and 41 women without PE. Preterm PE (92%) was associated with more MVM than term PE (10%, p < 0.01) and controls (4%, p < 0.01), but the rate of MVM was similar between term PE and controls (p = 0.56). Preterm PE was also associated with more placental infarcts (65% vs. 20% vs. 15%); advanced villous maturation (91% vs. 30% vs. 1%); and hypoplastic villous maturation (70% vs. 10% vs. 3%); and moderate to severe decidual vasculopathy (56% vs. 10% vs. 3%) than term PE and controls (all p < 0.05). CONCLUSION: Most cases of preterm PE are associated with MVM, placental infarcts, advanced and/or hypoplastic villous maturation, and moderate to severe decidual vasculopathy, while it is infrequent in term PE and pregnancies without PE. Preterm and term preeclampsia have a different pathologic process that should be considered for their prevention and clinical management.

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

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

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

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

Pregnancy-induced Cardiovascular Pathologies: Importance of Structural Components and Lipids

Pregnancy leads to adaptations for maternal and fetal energy needs. The cardiovascular system bears the brunt of the adaptations as the heart and vessels enable nutrient supply to maternal organs facilitated by the placenta to the fetus. The components of the cardiovascular system are critical in the balance between maternal homeostatic and fetus driven homeorhetic regulation. Since lipids intersect maternal cardiovascular function and fetal needs with growth and in stress, factors affecting lipid deposition and mobilization impact risk outcomes. Here, the cardiovascular components and functional derangements associated with cardiovascular pathology in pregnancy, vis-à-vis lipid deposition, mobilization and maternal and/or cardiac and fetal energy needs are detailed. Most reports on the components and associated pathology in pregnancy, are on derangements affecting the extracellular matrix and epicardial fat, followed by the endothelium, vascular smooth muscle, pericytes and myocytes. Targeted studies on all cardiovascular components and pathological outcomes in pregnancy will enhance targeted interventions.

The impact of previous live births on peripheral and uterine natural killer cells in patients with recurrent miscarriage

BACKGROUND

Peripheral and uterine natural killer cells (pNK and uNK cells) are key players in the establishment and maintenance of pregnancy and are disturbed in patients with recurrent miscarriage (RM). Different immunologic risk factors have been proposed between patients with primary RM (pRM, no previous live birth) and secondary RM (sRM, ≥ 1 previous live birth). However, so far, the study populations mainly consisted of small subgroups. Therefore, we aimed to analyse pNK and uNK cells in a large, well defined study population within a prospective study.

METHODS

In total, n = 575 RM patients (n = 393 pRM, n = 182 sRM) were screened according to a standard protocol for established risk factors as well as pNK and uNK cells. Peripheral blood levels of CD45⁺CD3^-CD56⁺CD16⁺ NK cells were determined by flow cytometry and uterine CD56⁺ NK cells by immunohistochemistry in mid-luteal non-pregnant RM patients. Exclusion of patients with ≥1 established risk factor revealed n = 248 idiopathic RM patients (iRM, n = 167 primary iRM (ipRM), n = 81 secondary iRM (isRM)).

RESULTS

Patients with pRM and ipRM showed significant higher absolute numbers and percentages of pNK cells compared to sRM and isRM patients (pRM/ipRM vs sRM/isRM, mean ± SD /μl: 239.1 ± 118.7/244.9 ± 112.9 vs 205.1 ± 107.9/206.0 ± 105.6, p = 0.004/ p = 0.009; mean ± SD %: 12.4 ± 5.5/12.8 ± 5.4 vs 11.1 ± 4.6/11.1 ± 4.3, p = 0.001; p = 0.002). Only patients with isRM showed significantly higher uNK levels compared to patients with ipRM (mean ± SD /mm² 288.4 ± 239.3 vs 218.2 ± 184.5, p = 0.044).

CONCLUSIONS

The demonstrated differences in pNK and uNK cells in RM patients depending on previous live birth might indicate differences in NK cell recruitment and potentially different underlying immune disorders between pRM and sRM. As there is an overlap in the distribution of the NK cell results, further studies with focus on NK cell function are needed in order to clearly identify RM patients with distinct immune abnormalities. The clinical relevance of our findings should be interpreted cautiously until specificity and sensitivity are further evaluated.