Innate immune cells in the placental bed in healthy pregnancy and preeclampsia

Exploring altered free amino acids and metabolites: Insights into the metabolic landscape of preeclampsia

INTRODUCTION

Preeclampsia (PE) is a complex disease that poses a risk for maternal and perinatal morbidity and mortality. This study aimed to investigate the role of maternal serum amino acids (AAs) levels in PE.

MATERIALS AND METHODS

A total of 56 pregnant women (26 with PE and 30 controls) were included in the study. The participants had a confirmed gestational age between 24 and 37 weeks. The mean body mass index (BMI) for the PE group was 33.1 kg/m2, while the control group had a mean BMI of 29.6 kg/m2. AAs levels were quantified, and statistical analyses were performed to identify significant differences between the two groups. Receiver Operating Characteristic (ROC) curve analysis was employed the diagnostic potential of specific AAs.

RESULTS

We observed significantly elevated levels of multiple AAs in the PE group, including citrulline, lysine, ethanolamine, ornithine and histidine. Citrulline exhibited exceptional predictive power for PE with 100.0% sensitivity and specificity at a cutoff of 7.79 µmol/L, reflected in an area under the curve (AUC) of 1.000.

DISCUSSION

Our study highlights the crucial involvement of altered amino acid levels, specifically in the urea cycle, disruptions in lysine and ethanolamine metabolism in PE development. Exploring these changes may reveal new therapeutic targets, providing insights into the disease's molecular mechanisms. Understanding amino acid metabolism in PE not only informs therapeutic strategies but also holds the potential to revolutionize early diagnosis and intervention.

Maternal obesity and placental function: impaired maternal-fetal axis

The prevalence of maternal obesity rapidly increases, which represents a major public health concern worldwide. Maternal obesity is characteristic by metabolic dysfunction and chronic inflammation. It is associated with health problems in both mother and offspring. Increasing evidence indicates that the placenta is an axis connecting maternal obesity with poor outcomes in the offspring. In this brief review, we have summarized the current data regarding deregulated placental function in maternal obesity. The data show that maternal obesity induces numerous placental defects, including lipid and glucose metabolism, stress response, inflammation, immune regulation and epigenetics. These placental defects affect each other and result in a stressful intrauterine environment, which transduces and mediates the adverse effects of maternal obesity to the fetus. Further investigations are required to explore the exact molecular alterations in the placenta in maternal obesity, which may pave the way to develop specific interventions for preventing epigenetic and metabolic programming in the fetus.

Bioinformatic Analysis Identifies Potential Extracellular Matrix Related Genes in the Pathogenesis of Early Onset Preeclampsia

Early-onset preeclampsia (EOPE) is a complex pregnancy complication that poses significant risks to the health of both mothers and fetuses, and research on its pathogenesis and pathophysiology remains insuffcient. This study aims to explore the role of candidate genes and their potential interaction mechanisms in EOPE through bioinformatics analysis techniques. Two gene expression datasets, GSE44711 and GSE74341, were obtained from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs) between EOPE and gestational age-matched preterm control samples. Functional enrichment analysis was performed utilizing the kyoto encyclopedia of genes and genomes (KEGG), gene ontology (GO), and gene set enrichment analysis (GSEA). A protein-protein interaction (PPI) network was constructed using the STRING database, and hub DEGs were identified through Cytoscape software and comparative toxicogenomics database (CTD) analysis. Furthermore, a diagnostic logistic model was established using these hub genes, which were confirmed through reverse transcription polymerase chain reaction (RT-PCR). Finally, immune cell infiltration was analyzed using CIBERSORT. In total, 807 DEGs were identified in the GSE44711 dataset (451 upregulated genes and 356 downregulated genes), and 787 DEGs were identified in the GSE74341 dataset (446 upregulated genes and 341 downregulated genes). These DEGs were significantly enriched in various molecular functions such as extracellular matrix structural constituent, receptor-ligand activity binding, cytokine activity, and platelet-derived growth factor. KEGG and GSEA annotation revealed significant enrichment in pathways related to ECM-receptor interaction, PI3K-AKT signaling, and focal adhesion. Ten hub genes were identified through the CytoHubba plugin in Cytoscape. Among these hub genes, three key DEGs (COL1A1, SPP1, and THY1) were selected using CTD analysis and various topological methods in Cytoscape. The diagnostic logistic model based on these three genes exhibited high efficiency in predicting EOPE (AUC = 0.922). RT-PCR analysis confirmed the downregulation of these genes in EOPE, and immune cell infiltration analysis suggested the significant role of M1 and M2 macrophages in EOPE. In conclusion, this study highlights the association of three key genes (COL1A1, SPP1, and THY1) with EOPE and their contribution to high diagnostic efficiency in the logistic model. Additionally, it provides new insights for future research on EOPE and emphasizes the diagnostic value of these identified genes. More research is needed to explore their functional and diagnostic significance in EOPE.

Non-coding RNA regulates the immune microenvironment in recurrent spontaneous abortion (RSA): new insights into immune mechanisms†

Recurrent spontaneous abortion (RSA) has various causes, including chromosomal abnormalities, prethrombotic state, and abnormal uterine anatomical factors. However, the pathogenesis of RSA is still unclear. Surprisingly, non-coding RNA can stably express at the maternal-fetal interface and regulate immune cells' proliferation, apoptosis, invasion, metastasis, and angiogenesis. Accumulating evidence suggests that the competing endogenous RNA (ceRNA) regulatory network between non-coding RNAs complicates RSA's pathological process and maybe a new starting point for exploring RSA. In this review, we mainly discuss the regulatory network and potential significance of non-coding RNA in the immune microenvironment of RSA patients. In addition, the cellular interactions of non-coding RNA transported through vesicles were introduced from aspects of trophoblast function and immune regulation. Finally, we analyze previous studies and further discuss that the stable expression of non-coding RNA may be used as a biomarker of some disease states and a prediction target of RSA.

Melatonin: the placental antioxidant and anti-inflammatory

Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone with many physiological and biological roles. Melatonin is an antioxidant, anti-inflammatory, free radical scavenger, circadian rhythm regulator, and sleep hormone. However, its most popular role is the ability to regulate sleep through the circadian rhythm. Interestingly, recent studies have shown that melatonin is an important and essential hormone during pregnancy, specifically in the placenta. This is primarily due to the placenta's ability to synthesize its own melatonin rather than depending on the pineal gland. During pregnancy, melatonin acts as an antioxidant and anti-inflammatory, which is necessary to ensure a stable environment for both the mother and the fetus. It is an essential antioxidant in the placenta because it reduces oxidative stress by constantly scavenging for free radicals, i.e., maintain the placenta's integrity. In a healthy pregnancy, the maternal immune system is constantly altered to accommodate the needs of the growing fetus, and melatonin acts as a key anti-inflammatory by regulating immune homeostasis during early and late gestation. This literature review aims to identify and summarize melatonin's role as a powerful antioxidant and anti-inflammatory that reduces oxidative stress and inflammation to maintain a favorable homeostatic environment in the placenta throughout gestation.

Oncostatin M and STAT3 Signaling Pathways Support Human Trophoblast Differentiation by Inhibiting Inflammatory Stress in Response to IFNγ and GM-CSF

Interleukin-6 (IL-6) superfamily cytokines play critical roles during human pregnancy by promoting trophoblast differentiation, invasion, and endocrine function, and maintaining embryo immunotolerance and protection. In contrast, the unbalanced activity of pro-inflammatory factors such as interferon gamma (IFNγ) and granulocyte-macrophage colony-stimulating factor (GM-CSF) at the maternal-fetal interface have detrimental effects on trophoblast function and differentiation. This study demonstrates how the IL-6 cytokine family member oncostatin M (OSM) and STAT3 activation regulate trophoblast fusion and endocrine function in response to pro-inflammatory stress induced by IFNγ and GM-CSF. Using human cytotrophoblast-like BeWo (CT/BW) cells, differentiated in villous syncytiotrophoblast (VST/BW) cells, we show that beta-human chorionic gonadotrophin (βhCG) production and cell fusion process are affected in response to IFNγ or GM-CSF. However, those effects are abrogated with OSM by modulating the activation of IFNγ-STAT1 and GM-CSF-STAT5 signaling pathways. OSM stimulation enhances the expression of STAT3, the phosphorylation of STAT3 and SMAD2, and the induction of negative regulators of inflammation (e.g., IL-10 and TGFβ1) and cytokine signaling (e.g., SOCS1 and SOCS3). Using STAT3-deficient VST/BW cells, we show that STAT3 expression is required for OSM to regulate the effects of IFNγ in βhCG and E-cadherin expression. In contrast, OSM retains its modulatory effect on GM-CSF-STAT5 pathway activation even in STAT3-deficient VST/BW cells, suggesting that OSM uses STAT3-dependent and -independent mechanisms to modulate the activation of pro-inflammatory pathways IFNγ-STAT1 and GM-CSF-STAT5. Moreover, STAT3 deficiency in VST/BW cells leads to the production of both a large amount of βhCG and an enhanced expression of activated STAT5 induced by GM-CSF, independently of OSM, suggesting a key role for STAT3 in βhCG production and trophoblast differentiation through STAT5 modulation. In conclusion, our study describes for the first time the critical role played by OSM and STAT3 signaling pathways to preserve and regulate trophoblast biological functions during inflammatory stress.

Abnormal M1 polarization of placental macrophage induced by IL-15/STAT5 activation in VVC may lead to adverse pregnancy outcomes

Pregnant women with vulvovaginal candidiasis (VVC) may experience adverse pregnancy outcomes such as premature delivery, intrauterine infection, abortion, and neonatal infection. Therefore, finding new treatments for VVC in pregnancy is a public health priority. We aimed to study the adverse consequences of Candida albicans (C. albicans) vaginal infection in pregnant mice and explore the mechanisms by which C. albicans affects macrophages. Our findings contribute to the development of new approaches to treat VVC during pregnancy. We established an animal model of vaginal infection by C. albicans in pregnant mice and observed adverse pregnancy outcomes such as decreased body weight, reduced implantation number, and increased abortion rates. Additionally, we infected mouse macrophage line RAW264.7 cells with C. albicans and established a cell model. We employed RT-qPCR, Western blot, and immunofluorescence staining to verify the changes in the IL-15/STAT5 signaling pathway and the role it played on the M1 polarization of C. albicans-infected macrophages at both the gene and protein levels. Our results indicate that the adverse pregnancy outcomes in VVC may be linked to changes in the IL-15/STAT5 pathway induced by C. albicans, which could impact macrophage M1 polarization.

Demystifying the impact of prenatal tobacco exposure on the placental immune microenvironment: Avoiding the tragedy of mending the fold after death

Prenatal tobacco exposure (PTE) correlates significantly with a surge in adverse pregnancy outcomes, yet its pathological mechanisms remain partially unexplored. This study aims to meticulously examine the repercussions of PTE on placental immune landscapes, employing a coordinated research methodology encompassing bioinformatics, machine learning and animal studies. Concurrently, it aims to screen biomarkers and potential compounds that could sensitively indicate and mitigate placental immune disorders. In the course of this research, two gene expression omnibus (GEO) microarrays, namely GSE27272 and GSE7434, were included. Gene set enrichment analysis (GSEA) and immune enrichment investigations on differentially expressed genes (DEGs) indicated that PTE might perturb numerous innate or adaptive immune-related biological processes. A cohort of 52 immune-associated DEGs was acquired by cross-referencing the DEGs with gene sets derived from the ImmPort database. A protein-protein interaction (PPI) network was subsequently established, from which 10 hub genes were extracted using the maximal clique centrality (MCC) algorithm (JUN, NPY, SST, FLT4, FGF13, HBEGF, NR0B2, AREG, NR1I2, SEMA5B). Moreover, we substantiated the elevated affinity of tobacco reproductive toxicants, specifically nicotine and nitrosamine, with hub genes through molecular docking (JUN, FGF13 and NR1I2). This suggested that these genes could potentially serve as crucial loci for tobacco's influence on the placental immune microenvironment. To further elucidate the immune microenvironment landscape, consistent clustering analysis was conducted, yielding three subtypes, where the abundance of follicular helper T cells (p < 0.05) in subtype A, M2 macrophages (p < 0.01), neutrophils (p < 0.05) in subtype B and CD8+ T cells (p < 0.05), resting NK cells (p < 0.05), M2 macrophages (p < 0.05) in subtype C were significantly different from the control group. Additionally, three pivotal modules, designated as red, blue and green, were identified, each bearing a close association with differentially infiltrated immunocytes, as discerned by the weighted gene co-expression network analysis (WGCNA). Functional enrichment analysis was subsequently conducted on these modules. To further probe into the mechanisms by which immune-associated DEGs are implicated in intercellular communication, 20 genes serving as ligands or receptors and connected to differentially infiltrating immunocytes were isolated. Employing a variety of machine learning techniques, including one-way logistic regression, LASSO regression, random forest and artificial neural networks, we screened 11 signature genes from the intersection of immune-associated DEGs and secretory protein-encoding genes derived from the Human Protein Atlas. Notably, CCL18 and IFNA4 emerged as prospective peripheral blood markers capable of identifying PTE-induced immune disorders. These markers demonstrated impressive predictive power, as indicated by the area under the curve (AUC) of 0.713 (0.548-0.857) and 0.780 (0.618-0.914), respectively. Furthermore, we predicted 34 potential compounds, including cyclosporine, oestrogen and so on, which may engage with hub genes and attenuate immune disorders instigated by PTE. The diagnostic performance of these biomarkers, alongside the interventional effect of cyclosporine, was further corroborated in animal studies via ELISA, Western blot and immunofluorescence assays. In summary, this study identifies a disturbance in the placental immune landscape, a secondary effect of PTE, which may underlie multiple pregnancy complications. Importantly, our research contributes to the noninvasive and timely detection of PTE-induced placental immune disorders, while also offering innovative therapeutic strategies for their treatment.

Multimodal profiling of term human decidua demonstrates immune adaptations with pregravid obesity

Leukocyte diversity of the first-trimester maternal-fetal interface has been extensively described; however, the immunological landscape of the term decidua remains poorly understood. We therefore profiled human leukocytes from term decidua collected via scheduled cesarean delivery. Relative to the first trimester, our analyses show a shift from NK cells and macrophages to T cells and enhanced immune activation. Although circulating and decidual T cells are phenotypically distinct, they demonstrate significant clonotype sharing. We also report significant diversity within decidual macrophages, the frequency of which positively correlates with pregravid maternal body mass index. Interestingly, the ability of decidual macrophages to respond to bacterial ligands is reduced with pregravid obesity, suggestive of skewing toward immunoregulation as a possible mechanism to safeguard the fetus against excessive maternal inflammation. These findings are a resource for future studies investigating pathological conditions that compromise fetal health and reproductive success.

Single-cell RNA-seq reveals developmental deficiencies in both the placentation and the decidualization in women with late-onset preeclampsia

Preeclampsia (PE) is a leading cause of maternal and fetal morbidity and mortality. Although increasing lines of evidence suggest that both the placenta and the decidua likely play roles in the pathogenesis of PE, the molecular mechanism of PE remains elusive partly because of the heterogeneity nature of the maternal-fetal interface. In this study, we perform single-cell RNA-seq on the placenta and the decidual from patients with late-onset PE (LOPE) and women in normal pregnancy. Analyses of single-cell transcriptomes reveal that in LOPE, there are likely a global development deficiency of trophoblasts with impaired invasion of extravillous trophoblasts (EVT) and increased maternal immune rejection and inflammation in the placenta, while there are likely insufficient decidualization of decidual stromal cells (DSC), increased inflammation, and suppressed regulatory functions of decidual immune cells. These findings improve our understanding of the molecular mechanisms of PE.

Downregulation of miR-455-3p in decidual cells promotes macrophage polarization and suppresses trophoblasts invasion

Preeclampsia (PE) is a common complication of pregnancy, usually accompanied by symptoms such as hypertension and proteinuria. It can induce severe conditions that may result in maternal and fetal morbidity and fatality. In this study, we use bioinformatics analysis to compare microRNA microassay in decidual stromal cells from PE patients and healthy donors. Our result indicated that placentas from PE patients had a higher CCL1/CXCL2 expression, compared with those from healthy donors. Bioinformatics analysis confirmed that decidual stromal cells derived from PE patients expressed significantly lower miR-455-3p than those derived from healthy donors. Transfection of miR-455-3p inhibitors enhanced the CCL2/CXCL8 expression in decidual stromal cells, and luciferase activity assay confirmed that nuclear factor of activated T cells 5 (NFAT5) mRNA was the direct target of miR-455-3p; NFAT5 also promoted cytokine secretion. In the flow cytometry study, higher M1 macrophage infiltration was observed in placentas from PE patients than in those from healthy donors. We also observed that condition medium (CM) derived from decidual stromal cells could significantly promote M1 polarization of macrophages after transfection with miR-455-3p inhibitor; further, transwell invasion assay confirmed that decidual stromal cells-CM educated macrophages suppressed trophoblast invasion. Taken together, our result demonstrates that downregulation of miR-455-3p in decidual stromal cells can promote macrophage polarization and suppress trophoblasts invasion.

SSRI treatment modifies the effects of maternal inflammation on in utero physiology and offspring neurobiology

Perturbations to the in utero environment can dramatically change the trajectory of offspring neurodevelopment. Insults commonly encountered in modern human life such as infection, toxins, high-fat diet, prescription medications, and others are increasingly linked to behavioral alterations in prenatally-exposed offspring. While appreciation is expanding for the potential consequence that these triggers can have on embryo development, there is a paucity of information concerning how the crucial maternal-fetal interface (MFI) responds to these various insults and how it may relate to changes in offspring neurodevelopment. Here, we found that the MFI responds both to an inflammatory state and altered serotonergic tone in pregnant mice. Maternal immune activation (MIA) triggered an acute inflammatory response in the MFI dominated by interferon signaling that came at the expense of ordinary development-related transcriptional programs. The major MFI compartments, the decidua and the placenta, each responded in distinct manners to MIA. MFIs exposed to MIA were also found to have disrupted sex-specific gene expression and heightened serotonin levels. We found that offspring exposed to MIA had sex-biased behavioral changes and that microglia were not transcriptionally impacted. Moreover, the combination of maternal inflammation in the presence of pharmacologic inhibition of serotonin reuptake further transformed MFI physiology and offspring neurobiology, impacting immune and serotonin signaling pathways alike. In all, these findings highlight the complexities of evaluating diverse environmental impacts on placental physiology and neurodevelopment.

Single cell RNA sequencing research in maternal fetal interface

The maternal-fetal interface is an essential environment for embryonic growth and development, and a successful pregnancy depends on the dynamic balance of the microenvironment at the maternal-fetal interface. Single-cell sequencing, which unlike bulk sequencing that provides averaged data, is a robust method for interpreting the cellular and molecular landscape at single-cell resolution. With the support of single-cell sequencing, the issue of maternal-fetal interface heterogeneity during pregnancy has been more deeply elaborated and understood, which is important for a deeper understanding of physiological and pathological pregnancy. In this paper, we analyze the recent studies of single-cell transcriptomics in the maternal-fetal interface, and provide new directions for understanding and treating various pathological pregnancies.

Potential molecular and cellular mechanisms for adverse placental outcomes in pregnancies complicated by SARS-CoV-2 infection-A scoping review

BACKGROUND

Emerging evidence suggests that SARS-CoV-2 infection during pregnancy can result in placental damage and poor placental outcomes. However, the mechanisms by which SARS-CoV-2 infection leads to placental damage are not well understood. With a rapid expansion of literature on this topic, it is critical to assess the quality and synthesize the current state of literature. The objective of this scoping review is to highlight underlying mechanisms of SARS-CoV-2 mediated placental pathology in pregnant individuals and identify literature gaps regarding molecular and cellular mechanisms of poor placental outcomes.

METHODS

The review was conducted and reported following the recommendations of the PRISMA extension for Scoping Reviews. The study protocol was registered with Open Science Framework (https://osf.io/p563s/). Five databases (MEDLINE, EMBASE, Scopus, CINAHL, PubMed) were searched for studies published between September 2019 until April 2022. Studies assessing placental outcomes with respect to SARS-CoV-2 infection in pregnancy were eligible for inclusion. Outcomes of interest included histopathology, and molecular or cellular analysis. All records were uploaded into Covidence and extracted using the Joanna Briggs Institute method. Studies were assessed for risk of bias using the Newcastle Ottawa scale and a narrative synthesis of results was generated.

RESULTS

Twenty-seven studies reporting on molecular and/or cellular mechanisms of SARS-CoV-2 mediated placental outcomes were included in this review. SARS-CoV-2 infection was associated with perturbations in the ACE2 pathway, inflammatory mediators and immune cell populations and mitochondrial function in placentas.

CONCLUSIONS

Our findings suggest that changes in the ACE2 pathway, mitochondrial dysfunction, and/or inflammatory processes may lead to placental damage observed in SARS-CoV-2 infection during pregnancy. More research is needed to understand the role of these pathways further, in addition to data collection related to trimester, severity, and strain.

Setting a stage: Inflammation during preeclampsia and postpartum

Preeclampsia (PE) is a leading cause of maternal and fetal mortality worldwide. The immune system plays a critical role in normal pregnancy progression; however, inappropriate inflammatory responses have been consistently linked with PE pathophysiology. This inflammatory phenotype consists of activation of the innate immune system, adaptive immune system, and increased inflammatory mediators in circulation. Moreover, recent studies have shown that the inflammatory profile seen in PE persists into the postpartum period. This manuscript aims to highlight recent advances in research relating to inflammation in PE as well as the inflammation that persists postpartum in women after a PE pregnancy. With the advent of the COVID-19 pandemic, there has been an increase in obstetric disorders associated with COVID-19 infection during pregnancy. This manuscript also aims to shed light on the relationship between COVID-19 infection during pregnancy and the increased incidence of PE in these women.

HIF1 inhibitor acriflavine rescues early-onset preeclampsia phenotype in mice lacking placental prolyl hydroxylase domain protein 2

Preeclampsia is a serious pregnancy disorder that lacks effective treatments other than delivery. Improper sensing of oxygen changes during placentation by prolyl hydroxylases (PHDs), specifically PHD2, causes placental hypoxia-inducible factor-1 (HIF1) buildup and abnormal downstream signaling in early-onset preeclampsia, yet therapeutic targeting of HIF1 has never been attempted. Here we generated a conditional (placenta-specific) knockout of Phd2 in mice (Phd2-/- cKO) to reproduce HIF1 excess and to assess anti-HIF therapy. Conditional deletion of Phd2 in the junctional zone during pregnancy increased placental HIF1 content, resulting in abnormal placentation, impaired remodeling of the uterine spiral arteries, and fetal growth restriction. Pregnant dams developed new-onset hypertension at midgestation (E9.5) in addition to proteinuria and renal and cardiac pathology, hallmarks of severe preeclampsia in humans. Daily injection of acriflavine, a small molecule inhibitor of HIF1, to pregnant Phd2-/- cKO mice from E7.5 (prior to hypertension) or E10.5 (after hypertension had been established) to E14.5 corrected placental dysmorphologies and improved fetal growth. Moreover, it reduced maternal blood pressure and reverted renal and myocardial pathology. Thus, therapeutic targeting of the HIF pathway may improve placental development and function, as well as maternal and fetal health, in preeclampsia.

The Innate Defense in the Zika-Infected Placenta

Zika virus (ZIKV) is an arthropod-borne virus that belongs to the Flaviviridae family, genus Flavivirus and was first isolated 1947 in Uganda, Africa, from the serum of a sentinel Rhesus monkey. Since its discovery, the virus was responsible for major outbreaks in several different countries, being linked to severe complications in pregnant women, neonatal birth defects and the congenital zika syndrome. Maternal-fetal transmission of ZIKV can occur in all trimesters of pregnancy, and the role of the placenta and its cells in these cases is yet to be fully understood. The decidua basalis and chorionic villi, maternal-fetal components of the placenta, contain a rich immunological infiltrate composed by Hofbauer cells, mastocytes, dendritic cells and macrophages, primary cells of the innate immune response that have a role that still needs to be better investigated in ZIKV infection. Recent studies have already described several histopathological features and the susceptibility and permissiveness of placenta cells to infection by the Zika virus. In this review, we address some of the current knowledge on the innate immune responses against ZIKV, especially in the placenta.

A decreased number of circulating regulatory T cells is associated with adverse pregnancy outcomes in patients with systemic lupus erythematosus

OBJECTIVE

As an autoimmune disease affecting women of reproductive age, systemic lupus erythematosus (SLE) is linked to adverse fetal and maternal outcomes. However, the status of peripheral lymphocytes in SLE patients with different pregnancy outcomes is unclear. This retrospective cross-sectional study explored the relationship between lymphocyte subpopulations and pregnancy outcomes in married SLE female patients.

METHODS

The absolute numbers of peripheral T, helper T (Th)1, Th2, Th17, regulatory T (Treg), B, and natural killer (NK) cell subpopulations from 585 female SLE patients and 91 female healthy controls (HCs) were assessed. We compared the lymphocyte subpopulations in SLE patients with HCs and analyzed the absolute number and ratio of Treg cells according to pregnancy outcome in SLE patients.

RESULTS

SLE patients had decreased numbers of T, B, NK, Th1, Th2, Th17, and Treg cells and an imbalance in pro- and anti-inflammatory cells (p < .05), as well as adverse pregnancy outcomes. In abortion patients, the number of Treg cells (p = .008) decreased, leading to an imbalance in effector T and Treg cells. The ratio of Treg cells was higher in SLE patients with nulliparity than in those with one or two parities.

CONCLUSIONS

The absolute numbers of lymphocyte subpopulations in SLE patients decreased, which was associated with abortion and parity (p < .05). These results suggest that a loss of immune tolerance mediated by Tregs triggers pregnancy loss.

Immune Tolerance of Embryo Implantation and Pregnancy: The Role of Human Decidual Stromal Cell- and Embryonic-Derived Extracellular Vesicles

Embryo–endometrial communication plays a critical role in embryo implantation and the establishment of a successful pregnancy. Successful pregnancy outcomes involve maternal immune modulation during embryo implantation. The endometrium is usually primed and immunomodulated by steroid hormones and embryo signals for subsequent embryo implantation and the maintenance of pregnancy. The roles of extracellular vesicles (EVs) and microRNAs for the embryo–maternal interactions have been elucidated recently. New evidence shows that endometrial EVs and trophectoderm-originated EV cargo, including microRNAs, proteins, and lipids in the physiological microenvironment, regulate maternal immunomodulation for embryo implantation and subsequent pregnancy. On the other hand, trophoblast-derived EVs also control the cross-communication between the trophoblasts and immune cells. The exploration of EV functions and mechanisms in the processes of embryo implantation and pregnancy will shed light on a practical tool for the diagnostic or therapeutic approaches to reproductive medicine and infertility.

Isolation and characterization of uterine leukocytes collected using a uterine swab technique

PROBLEM

Leukocytes from the maternal-fetal interface are a valuable tool to study local changes in immune function during pregnancy; however, sampling can be challenging due to inadequate tissue availability and the invasive nature of placental bed biopsy. Here, we aim to purify and characterize leukocytes from paired peripheral and uterine blood samples to assess whether a less invasive method of uterine blood collection could yield a population of enriched uterine leukocytes suitable for ex vivo and in vitro analyses.

METHOD OF STUDY

Human peripheral blood mononuclear cells (PBMC) and uterine blood mononuclear cells (UBMC) expressed from surgical gauze post C-section were isolated, and immunophenotypic information was acquired by multi-parameter flow cytometry. PBMC and UBMC were stained for markers used to define T and B lymphocytes, macrophages, regulatory T (T_Reg ) cells, and natural killer (NK) cells. Prime flow was performed to check expression and analysis of CD16^- CD56⁺⁺ and CD16^- CD56++ NK transcripts in PBMC and UBMC samples.

RESULTS

Immunophenotyping revealed that over 95% of both live PBMC and UBMC consisted of CD45⁺ leukocytes. Higher percentages of CD16^- CD56⁺⁺ , characterized as uterine NK (uNK) cells, were observed in UBMC samples as compared to PBMC samples (18.41% of CD45⁺ CD3^- vs. 2.73%, respectively), suggesting that CD16^- CD56⁺⁺ cells were enriched in these samples. In UBMC, 49.64% of CD3-negative cells were of peripheral NK phenotype (CD16⁺ CD56⁺⁺ ), suggesting infiltration of maternal peripheral NK (pNK) cell in the uterine interface.

CONCLUSION

Intrauterine leukocytes, especially CD16^- CD56⁺⁺ NK cells, can be collected in sufficient numbers with increased purity by sampling the uterine cavity postdelivery with surgical gauze. Our results suggest that this non-invasive protocol is a useful sampling technique for isolating CD16^- CD56⁺⁺ cells, however, due to peripheral blood contamination, the NK cell yield could be lower compared to actual decidual or endometrial samples post-partum which is more invasive.

Maternal obesity: new placental paradigms unfolded

The prevalence of maternal obesity is increasing at an alarming rate, and is providing a major challenge for obstetric practice. Adverse effects on maternal and fetal health are mediated by complex interactions between metabolic, inflammatory, and oxidative stress signaling in the placenta. Endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) are common downstream pathways of cell stress, and there is evidence that this conserved homeostatic response may be a key mediator in the pathogenesis of placental dysfunction. We summarize the current literature on the placental cellular and molecular changes that occur in obese women. A special focus is cast onto placental ER stress in obese pregnancy, which may provide a novel link for future investigation.

Trophoblast-Derived Extracellular Vesicles Promote Preeclampsia by Regulating Macrophage Polarization

BACKGROUND

Systemic inflammation caused by dysfunctional macrophages is a crucial pathogenetic event in preeclampsia (PE). Trophoblast-derived extracellular vesicles (T-EVs) are potent immune cell signaling modulators in pregnancy. Herein, we aimed to investigate T-EVs' effect and mechanism on macrophage polarization and its role in PE pathogenesis, which remain unclear.

METHODS

Flow cytometry and immunochemistry were used to determine placental macrophage phenotypes. T-EVs were immuno-isolated via placental alkaline phosphatase antibody and identified by transmission electron microscopy and nanoparticle tracking analysis. Quantitative real-time polymerase chain reaction and flow cytometry were used to examine the effects of T-EVs on macrophage polarization, and correlation analysis of T-EVs lipidomics and macrophages transcriptome were performed to explore how T-EVs modulate macrophages. Animal experiments were established to investigate the relationship among PE, T-EVs, and macrophages.

RESULTS

Macrophages shift from the M2 to M1 phenotype in the preeclamptic placenta. Also, T-EVs from women with PE (PE-EVs) significantly upregulated M1 gene markers and significantly downregulated CD163 expression in macrophages compared with T-EVs in women with normal pregnancies (NP-EVs). Mechanistically, correlation analysis with T-EVs lipidome and the transcriptome of macrophages treated with PE-EVs or NP-EVs indicated that 37 lipids altered in PE-EVs considerably affected classical inflammatory biological pathways in macrophages. Finally, animal experiments revealed that PE-EVs triggered PE-like symptoms in pregnant mice, which were alleviated after macrophage depletion.

CONCLUSIONS

T-EVs from women with PE could promote preeclampsia by inducing macrophage imbalance polarization, signifying a potential novel interventional target for the prevention and management of PE.

Reproductive biology research down under: highlights from the Australian and New Zealand Annual Meeting of the Society for Reproductive Biology, 2021

Against the backdrop of a global pandemic, the Society for Reproductive Biology (SRB) 2021 meeting reunited the Australian and New Zealand reproductive research community for the first time since 2019 and was the first virtual SRB meeting. Despite the recent global research disruptions, the conference revealed significant advancements in reproductive research, the importance of which span human health, agriculture, and conservation. A core theme was novel technologies, including the use of medical microrobots for therapeutic and sperm delivery, diagnostic hyperspectral imaging, and hydrogel condoms with potential beyond contraception. The importance of challenging the contraceptive status quo was further highlighted with innovations in gene therapies, non-hormonal female contraceptives, epigenetic semen analysis, and in applying evolutionary theory to suppress pest population reproduction. How best to support pregnancies, particularly in the context of global trends of increasing maternal age, was also discussed, with several promising therapies for improved outcomes in assisted reproductive technology, pre-eclampsia, and pre-term birth prevention. The unique insights gained via non-model species was another key focus and presented research emphasised the importance of studying diverse systems to understand fundamental aspects of reproductive biology and evolution. Finally, the meeting highlighted how to effectively translate reproductive research into policy and industry practice.

Mast Cell Activation Syndrome in COVID-19 and Female Reproductive Function: Theoretical Background vs. Accumulating Clinical Evidence

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can affect almost all systems and organs of the human body, including those responsible for reproductive function in women. The multisystem inflammatory response in COVID-19 shows many analogies with mast cell activation syndrome (MCAS), and MCAS may be an important component in the course of COVID-19. Of note, the female sex hormones estradiol (E2) and progesterone (P4) significantly influence mast cell (MC) behavior. This review presents the importance of MCs and the mediators from their granules in the female reproductive system, including pregnancy, and discusses the mechanism of potential disorders related to MCAS. Then, the available data on COVID-19 in the context of hormonal disorders, the course of endometriosis, female fertility, and the course of pregnancy were compiled to verify intuitively predicted threats. Surprisingly, although COVID-19 hyperinflammation and post-COVID-19 illness may be rooted in MCAS, the available clinical data do not provide grounds for treating this mechanism as significantly increasing the risk of abnormal female reproductive function, including pregnancy. Further studies in the context of post COVID-19 condition (long COVID), where inflammation and a procoagulative state resemble many aspects of MCAS, are needed.

Mast cell-derived exosomal miR-181a-5p modulated trophoblast cell viability, migration, and invasion via YY1/MMP-9 axis

Background

Mast cells regulate the process of preeclampsia (PE). Since we previously identified mast cells specifically expressing miR‐181a‐5p in the placenta of PE patients, it is plausible to examine the effect and mechanism of mast cell‐derived exosomal miR‐181a‐5p on trophoblast cells.

Methods

The miR‐181a‐5p and YY1 levels were determined by quantitative real‐time reverse transcription‐polymerase chain reaction. Exosomes were identified by transmission electron microscopy, Western blot, and PKH‐26 labeling. Mast cells or trophoblast cell malignant phenotype were detected using 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide, wound healing, and Transwell assays. Quantification of YY1 and metastasis‐related proteins was performed using Western blot. TargetScan, JASPAR, dual‐luciferase reporter genes, and chromatin immunoprecipitation were exploited to verify the relationship between miR‐181a‐5p, YY1, and MMP‐9.

Results

MiR‐181a‐5p was overexpressed in mast cells of PE patients. Overexpressed miR‐181a‐5p restrained mast cell viability. Mast cell exosomes were successfully isolated, containing high expressions of CD63 and HSP70 and low expression of Calnexin and could be transported to the cytoplasm of trophoblast cells. Mast cell exosomes attenuated the viability, migration, and invasion of HTR‐8/SVneo cells, inhibited YY1, N‐cadherin, Vimentin, and MMP‐9 protein expressions, and promoted E‐cadherin protein expression. The effect of exosomes was enhanced by miR‐181a‐5p mimic but was reversed by miR‐181a‐5p inhibitor. MiR‐181a‐5p targeted YY1 which bound to the MMP‐9 promoter. Overexpressed YY1 in HTR‐8/SVneo cells accelerated the malignant phenotype of the cells and reversed the regulatory effects of exosomal miR‐181a‐5p.

Conclusion

Mast cell‐derived exosomal miR‐181a‐5p modulates HTR‐8/SVneo cell viability, migration, and invasion via YY1/MMP‐9.

The metabolic characteristic of decidual immune cells and their unique properties in pregnancy loss

Maternal tolerance to semi- or fully allograft conceptus is a prerequisite for the maintenance of pregnancy. Once this homeostasis is disrupted, it may result in pregnancy loss. As a potential approach to prevent pregnancy loss, targeting decidual immune cells (DICs) at the maternal-fetal interface has been suggested. Although the phenotypic features and functions of DIC have been extensively profiled, the regulatory pathways for this unique immunological adaption have yet to be elucidated. In recent years, a pivotal mechanism has been highlighted in the area of immunometabolism, by which the changes in intracellular metabolic pathways in DIC and interaction with the adjacent metabolites in the microenvironment can alter their phenotypes and function. More inspiringly, the manipulation of metabolic profiling in DIC provides a novel avenue for the prevention and treatment of pregnancy loss. Herein, this review highlights the major metabolic programs (specifically, glycolysis, ATP-adenosine metabolism, lysophosphatidic acid metabolism, and amino acid metabolism) in multiple immune cells (including decidual NK cells, macrophages, and T cells) and their integrations with the metabolic microenvironment in normal pregnancy. Importantly, this perspective may help to provide a potential therapeutic strategy for reducing pregnancy loss via targeting this interplay.

Interactions between Macrophages and Mast Cells in the Female Reproductive System

Mast cells (MCs) and macrophages (Mϕs) are innate immune cells that differentiate from early common myeloid precursors and reside in all body tissues. MCs have a unique capacity to neutralize/degrade toxic proteins, and they are hypothesized as being able to adopt two alternative polarization profiles, similar to Mϕs, with distinct or even opposite roles. Mϕs are very plastic phagocytic cells that are devoted to the elimination of senescent/anomalous endogenous entities (to maintain tissue homeostasis), and to the recognition and elimination of exogenous threats. They can adopt several functional phenotypes in response to microenvironmental cues, whose extreme profiles are the inflammatory/killing phenotype (M1) and the anti-inflammatory/healing phenotype (M2). The concomitant and abundant presence of these two cell types and the partial overlap of their defensive and homeostatic functions leads to the hypothesis that their crosstalk is necessary for the optimal coordination of their functions, both under physiological and pathological conditions. This review will examine the relationship between MCs and Mϕs in some situations of homeostatic regulation (menstrual cycle, embryo implantation), and in some inflammatory conditions in the same organs (endometriosis, preeclampsia), in order to appreciate the importance of their cross-regulation.

(Dis)similarities between the Decidual and Tumor Microenvironment

Placenta-specific trophoblast and tumor cells exhibit many common characteristics. Trophoblast cells invade maternal tissues while being tolerated by the maternal immune system. Similarly, tumor cells can invade surrounding tissues and escape the immune system. Importantly, both trophoblast and tumor cells are supported by an abetting microenvironment, which influences invasion, angiogenesis, and immune tolerance/evasion, among others. However, in contrast to tumor cells, the metabolic, proliferative, migrative, and invasive states of trophoblast cells are under tight regulatory control. In this review, we provide an overview of similarities and dissimilarities in regulatory processes that drive trophoblast and tumor cell fate, particularly focusing on the role of the abetting microenvironments.

Monocytes and macrophages in pregnancy: The good, the bad, and the ugly

A successful human pregnancy requires precisely timed adaptations by the maternal immune system to support fetal growth while simultaneously protecting mother and fetus against microbial challenges. The first trimester of pregnancy is characterized by a robust increase in innate immune activity that promotes successful implantation of the blastocyst and placental development. Moreover, early pregnancy is also a state of increased vulnerability to vertically transmitted pathogens notably, human immunodeficiency virus (HIV), Zika virus (ZIKV), SARS-CoV-2, and Listeria monocytogenes. As gestation progresses, the second trimester is marked by the establishment of an immunosuppressive environment that promotes fetal tolerance and growth while preventing preterm birth, spontaneous abortion, and other gestational complications. Finally, the period leading up to labor and parturition is characterized by the reinstatement of an inflammatory milieu triggering childbirth. These dynamic waves of carefully orchestrated changes have been dubbed the "immune clock of pregnancy." Monocytes in maternal circulation and tissue-resident macrophages at the maternal-fetal interface play a critical role in this delicate balance. This review will summarize the current data describing the longitudinal changes in the phenotype and function of monocyte and macrophage populations in healthy and complicated pregnancies.

Estrogen, the Peripheral Immune System and Major Depression – A Reproductive Lifespan Perspective

Major depression is a significant medical issue impacting millions of individuals worldwide. Identifying factors contributing to its manifestation has been a subject of intense investigation for decades and several targets have emerged including sex hormones and the immune system. Indeed, an extensive body of literature has demonstrated that sex hormones play a critical role in modulating brain function and impacting mental health, especially among female organisms. Emerging findings also indicate an inflammatory etiology of major depression, revealing new opportunities to supplement, or even supersede, currently available pharmacological interventions in some patient populations. Given the established sex differences in immunity and the profound impact of fluctuations of sex hormone levels on the immune system within the female, interrogating how the endocrine, nervous, and immune systems converge to impact women’s mental health is warranted. Here, we review the impacts of endogenous estrogens as well as exogenously administered estrogen-containing therapies on affect and immunity and discuss these observations in the context of distinct reproductive milestones across the female lifespan. A theoretical framework and important considerations for additional study in regards to mental health and major depression are provided.

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.

The Placental Innate Immune System Is Altered in Early-Onset Preeclampsia, but Not in Late-Onset Preeclampsia

Preeclampsia is a severe placenta-related pregnancy disorder that is generally divided into two subtypes named early-onset preeclampsia (onset <34 weeks of gestation), and late-onset preeclampsia (onset ≥34 weeks of gestation), with distinct pathophysiological origins. Both forms of preeclampsia have been associated with maternal systemic inflammation. However, alterations in the placental immune system have been less well characterized. Here, we studied immunological alterations in early- and late-onset preeclampsia placentas using a targeted expression profile approach. RNA was extracted from snap-frozen placenta samples (healthy n=13, early-onset preeclampsia n=13, and late-onset preeclampsia n=6). The expression of 730 immune-related genes from the Pan Cancer Immune Profiling Panel was measured, and the data were analyzed in the advanced analysis module of nSolver software (NanoString Technology). The results showed that early-onset preeclampsia placentas displayed reduced expression of complement, and toll-like receptor (TLR) associated genes, specifically TLR1 and TLR4. Mast cells and M2 macrophages were also decreased in early-onset preeclampsia compared to healthy placentas. The findings were confirmed by an immunohistochemistry approach using 20 healthy, 19 early-onset preeclampsia, and 10 late-onset preeclampsia placentas. We conclude that the placental innate immune system is altered in early-onset preeclampsia compared to uncomplicated pregnancies. The absence of these alterations in late-onset preeclampsia placentas indicates dissimilar immunological profiles. The study revealed distinct pathophysiological processes in early-onset and late-onset preeclampsia placentas and imply that a tailored treatment to each subtype is desirable.

Uncomplicated oocyte donation pregnancies display an elevated CD163-positive type 2 macrophage load in the decidua, which is associated with fetal-maternal HLA mismatches

PROBLEM

The embryo of an oocyte donation (OD) pregnancy is completely allogeneic to the mother, which may challenge the maternal immune system to tolerize the fetus. Decidual macrophages are essential in maintaining a healthy pregnancy, and type 2 macrophages may exhibit immune suppressive activity. We hypothesized that the composition of decidual macrophages is different between uncomplicated OD pregnancies and non-OD in vitro fertilization (IVF) pregnancies, and is related to fetal-maternal incompatibility.

METHOD OF STUDY

Women with uncomplicated pregnancy were enrolled: 25 singleton OD pregnancies and 17 non-OD IVF pregnancies. The extent of immunohistochemical staining of CD14 (pan-macrophage marker) and CD163 (type 2 macrophage marker) in both decidua basalis and parietalis was quantitated by digital image analysis. Maternal and fetal DNA was typed for human leukocyte antigen (HLA)-A, -B, C, -DRB1, and -DQB1, and fetal-maternal HLA mismatches were calculated.

RESULTS

OD pregnancies showed a higher percentage of CD163+ staining (P = .040) and higher CD163/CD14 ratio (P = .032) in the parietalis than non-OD IVF. The OD group was separated into a semi-allogeneic group (≤5 fetal maternal HLA mismatches) and a fully allogeneic group (> 5 mismatches). The HLA-fully-allogeneic OD group, but not the HLA-semi-allogeneic OD group, showed significantly elevated CD163/CD14 ratio in the parietalis compared with the non-OD IVF group (P < .05).

CONCLUSIONS

Uncomplicated OD pregnancies display a higher CD163-positive cell fraction in the total decidual macrophage population compared to autologous pregnancies, which may suggest that a local type 2 macrophage-related mechanism is needed to compensate for the higher fetal-maternal HLA mismatch load.

Uterine natural killer cell biology and role in early pregnancy establishment and outcomes

Objective

While immune cells were originally thought to only play a role in maternal tolerance of the semiallogenic fetus, an active role in pregnancy establishment is becoming increasingly apparent. Uterine natural killer (uNK) cells are of specific interest because of their cyclic increase in number during the window of implantation. As a distinct entity from their peripheral blood counterparts, understanding the biology and function of uNK cells will provide the framework for understanding their role in early pregnancy establishment and adverse pregnancy outcomes.

Evidence Review

This review discusses unique uNK cell characteristics and presents clinical implications resulting from their dysfunction. We also systematically present existing knowledge about uNK cell function in three processes critical for successful human embryo implantation and placentation: stromal cell decidualization, spiral artery remodeling, and extravillous trophoblast invasion. Finally, we review the features of uNK cells that could help guide future investigations.

Results

It is clear the uNK cells are intimately involved in multiple facets of early pregnancy. This is accomplished directly, through the secretion of factors that regulate stromal cells and trophoblast function; and indirectly, via interaction with other maternal cell types present at the maternal-fetal interface. Current work also suggests that uNK cells are a heterogenous population, with subsets that potentially accomplish different functions.

Conclusion

Establishment of pregnancy through successful embryo implantation and placentation requires crosstalk between multiple maternal cell types and invading fetal trophoblast cells. Defects in this process have been associated with multiple adverse perinatal outcomes including hypertensive disorders of pregnancy, placenta accreta, and recurrent miscarriage though the mechanism underlying development of these defects remain unclear. Abnormalities in NK cell number and function which would disrupt physiological maternal-fetal crosstalk, could play a critical role in abnormal implantation and placentation. It is therefore imperative to dissect the unique physiological role of uNK cells in pregnancy and use this knowledge to inform clinical practice by determining how uNK cell dysfunction could lead to reproductive failure.

Gestational Bell's Palsy Is Associated with Higher Blood Pressure during Late Pregnancy and Lower Birth Weight: A Retrospective Case-Control Study

The associations between gestational Bell's palsy (GBP) and late obstetric complications (LOCs), i.e., preeclampsia (PE), eclampsia (EC), gestational hypertension (GHT), and gestational diabetes mellitus (GDM) remain unclear. This study aimed to evaluate these associations and the neonatal health of the newborns born from pregnant women with and without GBP. A retrospective 1:5 case-control study matching exact maternal age and gravidity between pregnant women with and without GBP in Songklanagarind Hospital from 2006 to 2016 was conducted. The associations between GBP and PE, EC, GHT, and GDM, as well as comparison of the newborns' health indices were analyzed by bivariate analysis (p < 0.05). Eight GBP cases out of 8,756 pregnant women were recruited. Six GBP cases were first or second gravid. GBP occurred during the third trimester in five cases. Except for higher median systolic blood pressure (125 (114.2, 127.5) vs. (110 (107.0, 116.0), p = 0.045) and diastolic blood pressures (77 (73.0, 80.8) vs. 70 (65.0, 73.2), p = 0.021) in the GBP cases, associations between GBP and all LOCs could not be concluded due to the lack of power. However, a significantly lower mean birth weight in the newborns of GBP mothers was found (2672.2 (744.0) vs. 3154.8 (464.7), p = 0.016) with statistically significant power. Except for the higher blood pressures and lower birth weights of the newborns of GBP mothers, an association between GBP and LOCs remains inconclusive.

L-NAME, a nitric oxide synthase inhibitor, increases the protein expression of both executioner and inhibitor of apoptosis in the placental bed of mid-to-late pregnant rats

The involvement of nitric oxide (NO) signaling in apoptosis was examined in the placental bed of mid-to-late pregnant rats. Pregnant rats were treated with l-NAME, a nitric oxide synthase inhibitor, by subcutaneous infusion for 48 hours before the examination at day 13.5, 17.5, or 21.5. l-NAME induced apoptosis in the placental bed to a limited extent at days 13.5 and 17.5, but not at day 21.5. When the placental bed was examined at day 17.5, the protein expression of both executioner (C-Cas3) and inhibitor (XIAP) of apoptosis was increased by l-NAME, but they did not co-localized with apoptosis. It was presumed that placental bed apoptosis induced by l-NAME is regulated through the expression of both executioner and inhibitor, possibly involving protein S-nitrosylation.

Mifepristone regulates macrophage-mediated natural killer cells function in decidua

Mifepristone has been used for first-trimester abortion and contraception. Nevertheless, its functional mechanism still needs to be elucidated. Decidua tissues were collected from 40 pregnant women who received (20 patients) or did not receive (20 patients) mifepristone. Immunofluorescence was used to analyze the effect of mifepristone on the quantity of CD56 and CD206 in decidua. in vitro assay, NK cells were isolated from decidua tissue and macrophages were induced from THP-1 cells. NK cells were co-cultured with macrophages pre-treated different concentrations of mifepristone (0 nmol/L, 200 nmol/L, 1800 nmol/L, and 25000 nmol/L); the cells' cytotoxicity and migration ability were analyzed using MTT assay and transwell assay, respectively. Si-TGF-β1, which was utilized to knock down the TGF-β1 expression in macrophages and human recombinant TGF-β1 were used to verify whether TGF-β1 was involved in the mifepristone regulation of NK cells function. The quantity of CD56 and CD206 decreased after mifepristone treatment. Moreover, the NK cells' cytotoxicity and migration ability were significantly increased by macrophages pre-treated with mifepristone in a dose-dependent manner. Moreover, compared with the si-NC group, the MTT absorbance rate of NK cells was significantly increased in the si-TGF-β1 group and was decreased in the human recombinant TGF-β1 group. Our data suggest that mifepristone, which regulates NK cells function through macrophages, was associated with the changes in TGF-β1 secreted by macrophages. This may be one of the mechanisms of mifepristone acting as contraceptive and abortion drugs at the maternal-fetal interface.

Pre-eclampsia

Pre-eclampsia is a multisystem pregnancy disorder characterised by variable degrees of placental malperfusion, with release of soluble factors into the circulation. These factors cause maternal vascular endothelial injury, which leads to hypertension and multi-organ injury. The placental disease can cause fetal growth restriction and stillbirth. Pre-eclampsia is a major cause of maternal and perinatal mortality and morbidity, especially in low-income and middle-income countries. Prophylactic low-dose aspirin can reduce the risk of preterm pre-eclampsia, but once pre-eclampsia has been diagnosed there are no curative treatments except for delivery, and no drugs have been shown to influence disease progression. Timing of delivery is planned to optimise fetal and maternal outcomes. Clinical trials have reported diagnostic and prognostic strategies that could improve fetal and maternal outcomes and have evaluated the optimal timing of birth in women with late preterm pre-eclampsia. Ongoing studies are evaluating the efficacy, dose, and timing of aspirin and calcium to prevent pre-eclampsia and are evaluating other drugs to control hypertension or ameliorate disease progression.

Clinical consequences of defective decidualization

Decidualization is characterized by a series of genetic, metabolic, morphological, biochemical, vascular and immune changes occurring in the endometrial stroma in response to the implanting embryo or even before conception and involves the stromal cells of the endometrium. It is a fundamental reproductive event occurring in mammalian species with hemochorial placentation. A growing body of experimental and clinical evidence strongly suggests that defective or disrupted decidualization contributes to the establishment of an inappropriate maternal-fetal interface. This has relevant clinical consequences, ranging from recurrent implantation failure and recurrent pregnancy loss in early pregnancy to several significant complications of advanced gestation. Moreover, recent evidence indicates that selected diseases of the endometrium, such as chronic endometritis and endometriosis, can have a detrimental impact on the decidualization response in the endometrium and may help explain some aspects of the reduced reproductive outcome associated with these conditions. Further research efforts are needed to fully understand the biomolecular mechanisms ans events underlying an abnormal decidualization response. This will permit the development of new diagnostic and therapeutic strategies aimed to improve the likelihood of achieveing a successful pregnancy.

The Role of Immune Cells in Recurrent Spontaneous Abortion

Recurrent spontaneous abortion affects approximately 1–2% of women of childbearing, and describes a condition in which women suffer from three or more continuous spontaneous miscarriages. However, the origin of recurrent spontaneous abortion (RSA) remains unknown, preventing effective treatment and placing stress upon patients. It has been acknowledged that successful pregnancy necessitates balanced immune responses. Therefore, immunological aberrancy may be considered a root cause of poor pregnancy outcomes. Considerable published studies have investigated the relationship between various immune cells and RSA. Here, we review current knowledge on this area, and discuss the five main categories of immune cells involved in RSA; these include innate lymphocytes (ILC), macrophages, decidual dendritic cells (DCs), and T cells. Furthermore, we sought to summarize the impact of the multiple interactions of various immune cells on the emergence of RSA. A good understanding of pregnancy-induced immunological alterations could reveal new therapeutic strategies for favorable pregnancy outcomes.

The Immune Atlas of Human Deciduas With Unexplained Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is a common fertility problem that affects 1%-2% of couples all over the world. Despite exciting discoveries regarding the important roles of the decidual natural killer cell (dNK) and regulatory T cell in pregnancy, the immune heterogeneity in patients with unexplained recurrent pregnancy loss (URPL) remains elusive. Here, we profiled the transcriptomes of 13,953 CD45⁺ cells from three normal and three URPL deciduas. Based on our data, the cellular composition revealed three major populations of immune cells including dNK cell, T cell, and macrophage, and four minor populations including monocytes, dendritic cell (DC), mast cell, and B cell. Especially, we identified a subpopulation of CSF1+ CD59+ KIRs-expressing dNK cells in normal deciduas, while the proportion of this subpopulation was decreased in URPL deciduas. We also identified a small subpopulation of activated dDCs that were accumulated mainly in URPL deciduas. Furthermore, our data revealed that in decidua at early pregnancy, CD8⁺ T cells exhibited cytotoxic properties. The decidual macrophages expressed high levels of both M1 and M2 feature genes, which made them unique to the conventional M1/M2 classification. Our single-cell data revealed the immune heterogeneity in decidua and the potentially pathogenic immune variations in URPL.

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

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

Histamine, Metabolic Remodelling and Angiogenesis: A Systems Level Approach

Histamine is a highly pleiotropic biogenic amine involved in key physiological processes including neurotransmission, immune response, nutrition, and cell growth and differentiation. Its effects, sometimes contradictory, are mediated by at least four different G-protein coupled receptors, which expression and signalling pathways are tissue-specific. Histamine metabolism conforms a very complex network that connect many metabolic processes important for homeostasis, including nitrogen and energy metabolism. This review brings together and analyses the current information on the relationships of the "histamine system" with other important metabolic modules in human physiology, aiming to bridge current information gaps. In this regard, the molecular characterization of the role of histamine in the modulation of angiogenesis-mediated processes, such as cancer, makes a promising research field for future biomedical advances.

Local action of cytokines and immune cells in communication between the conceptus and uterus during the critical period of early embryo development, attachment and implantation - Implications for embryo survival in cattle: A review

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.

Epithelial membrane protein 2 (Emp2) modulates innate immune cell population recruitment at the maternal-fetal interface

Epithelial membrane protein 2 (EMP2) is a tetraspan membrane protein that has been revealed in cancer and placental models to mediate a number of vascular responses. Recently, Emp2 modulation has been shown to have an immunologic effect on uterine NK cell recruitment in the mouse placenta. Given the importance of immune cell populations on both placental vascularization and maternal immune tolerance of the developing fetus, we wanted to better characterize the immunologic effects of Emp2 at the placental-fetal interface. We performed flow cytometry of WT and Emp2 KO C57Bl/6 mouse uterine horns at GD12.5 to characterize immune cell populations localized to the various components of the maternal-fetal interface. We found that Emp2 KO decidua and placenta showed an elevated overall percentage of CD45+ cells compared to WT. Characterization of CD45+ cells in the decidua of Emp2 KO dams revealed an increase in NK cells, whereas in the placenta, Emp2 KO dams showed an increased percentage of M1 macrophages (with an increased ratio of M1/M2 macrophages). Given the differences detected in uNK cell populations in the decidua, we further characterized the interaction between Emp2 genetic KO and NK cell deletion via anti-asialo GM1 antibody injections. While the double knock-out of Emp2 and NK cells did not alter individual pup birthweight, it significantly reduced total litter weight and size by ∼50 %. In conclusion, Emp2 appears to regulate uNK and macrophage cell populations in pregnancy.

Crosstalk Between Trophoblasts and Decidual Immune Cells: The Cornerstone of Maternal-Fetal Immunotolerance

The success of pregnancy relies on the fine adjustment of the maternal immune system to tolerate the allogeneic fetus. Trophoblasts carrying paternal antigens are the only fetal-derived cells that come into direct contact with the maternal immune cells at the maternal–fetal interface. The crosstalk between trophoblasts and decidual immune cells (DICs) via cell–cell direct interaction and soluble factors such as chemokines and cytokines is a core event contributing to the unique immunotolerant microenvironment. Abnormal trophoblasts–DICs crosstalk can lead to dysregulated immune situations, which is well known to be a potential cause of a series of pregnancy complications including recurrent spontaneous abortion (RSA), which is the most common one. Immunotherapy has been applied to RSA. However, its development has been far less rapid or mature than that of cancer immunotherapy. Elucidating the mechanism of maternal–fetal immune tolerance, the theoretical basis for RSA immunotherapy, not only helps to understand the establishment and maintenance of normal pregnancy but also provides new therapeutic strategies and promotes the progress of immunotherapy against pregnancy-related diseases caused by disrupted immunotolerance. In this review, we focus on recent progress in the maternal–fetal immune tolerance mediated by trophoblasts–DICs crosstalk and clinical application of immunotherapy in RSA. Advancement in this area will further accelerate the basic research and clinical transformation of reproductive immunity and tumor immunity.

Baby Genomics: Tracing the Evolutionary Changes That Gave Rise to Placentation

It has long been challenging to uncover the molecular mechanisms behind striking morphological innovations such as mammalian pregnancy. We studied the power of a robust comparative orthology pipeline based on gene synteny to address such problems. We inferred orthology relations between human genes and genes from each of 43 other vertebrate genomes, resulting in ∼18,000 orthologous pairs for each genome comparison. By identifying genes that first appear coincident with origin of the placental mammals, we hypothesized that we would define a subset of the genome enriched for genes that played a role in placental evolution. We thus pinpointed orthologs that appeared before and after the divergence of eutherian mammals from marsupials. Reinforcing previous work, we found instead that much of the genetic toolkit of mammalian pregnancy evolved through the repurposing of preexisting genes to new roles. These genes acquired regulatory controls for their novel roles from a group of regulatory genes, many of which did in fact originate at the appearance of the eutherians. Thus, orthologs appearing at the origin of the eutherians are enriched in functions such as transcriptional regulation by Krüppel-associated box-zinc-finger proteins, innate immune responses, keratinization, and the melanoma-associated antigen protein class. Because the cellular mechanisms of invasive placentae are similar to those of metastatic cancers, we then used our orthology inferences to explore the association between placenta invasion and cancer metastasis. Again echoing previous work, we find that genes that are phylogenetically older are more likely to be implicated in cancer development.

Gestational gut microbial remodeling is impaired in a rat model of preeclampsia superimposed on chronic hypertension

Preeclampsia is a progressive hypertensive disorder of pregnancy affecting 2%-8% of pregnancies globally. Preexisting chronic hypertension is a major risk factor associated with developing preeclampsia, and growing evidence suggests a role for the gut microbiome in the development of preeclampsia. However, neither alterations in the gut microbiome associated with preeclampsia nor the mechanisms involved are fully understood. In this study, we tested the hypothesis that normal gestational maternal gut microbiome remodeling is impaired in the Dahl salt-sensitive (Dahl S) rat model of superimposed preeclampsia. Gut microbiome profiles of pregnant Dahl S, normal pregnant Sprague-Dawley (SD), and matched virgin controls were assessed by 16S rRNA gene sequencing at baseline; during early, middle, and late pregnancy; and 1-wk postpartum. Dahl S rats had significantly higher abundance in Proteobacteria, and multiple genera were significantly different from SD rats at baseline. The pregnant SD displayed a significant increase in Proteobacteria and genera such as Helicobacter, but these were not different between pregnant and virgin Dahl S rats. By late pregnancy, Dahl S rats had significantly lower α-diversity and Firmicutes compared with their virgin Dahl S controls. β-diversity was significantly different among groups (P < 0.001). KEGG metabolic pathways including those associated with short-chain fatty acids were different in Dahl S pregnancy but not in SD pregnancy. These results reveal an association between chronic hypertension and gut microbiome dysbiosis which may hinder pregnancy-specific remodeling in the gut microbial composition during superimposed preeclampsia.