The decidua of preeclamptic-like BPH/5 mice exhibits an exaggerated inflammatory response during early pregnancy

The PD-1 /PD-L1 signaling pathway regulates decidual macrophage polarization and may participate in preeclampsia

The pathogenesis of preeclampsia (PE) has not been elucidated, but immune imbalance is known to be one of the main pathogeneses. Dysfunction of decidual macrophages can lead to PE, and the PD-1/PD-L1 signaling pathway is associated with macrophage polarization. However, the relationship between the influence of the PD-1/PD-L1 signaling pathway on macrophage polarization and the onset of PE has not been fully elucidated. In this study, we analyzed the expression of CD68, iNOS, CD206, PD-1 and PD-L1 and the coexpression of CD68+PD-1+ and CD68+PD-L1+ in the decidual tissue of PE patients (n= 18) and healthy pregnant women (n=20). We found that CD68 and iNOS expression was increased in the decidua of PE patients (P < 0.001) and that CD206, PD-1 and PD-L1 expression and CD68+PD-1+ and CD68+PD-L1+ coexpression were decreased (P < 0.001). To assess the influence of the PD-1/PD-L1 signaling pathway on macrophage polarization, we added an anti-PD-1 mAb (pembrolizumab) or an anti-PD-L1 mAb (durvalumab) during THP-1 differentiation into M1 macrophages. Then, we detected the polarization of CD68+CD80+ macrophages and the expression of iNOS. To examine the effect of macrophage polarization on the invasion ability of trophoblast cells, macrophages were cocultured with HTR8/SVneo cells, and the invasion ability of HTR8/SVneo cells was detected via transwell assays. We found that CD68+CD80+ macrophage polarization was enhanced (P<0.05) and that iNOS expression was greater (P<0.01) in the pembrolizumab group. In the durvalumab group, CD68+CD80+ macrophage polarization and iNOS expression were also increased (P<0.05 and P<0.001). Compared with that in the untreated group, the aggressiveness of HTR8/SVneo cells was decreased in both the pembrolizumab group (P < 0.01) and the durvalumab group (P < 0.001). These findings indicate that the PD-1/PD-L1 signaling pathway may play an important role in the pathogenesis of PE by influencing macrophage polarization and reducing the invasion ability of trophoblasts.

Estrogen and Progesterone Receptors Are Dysregulated at the BPH/5 Mouse Preeclamptic-Like Maternal-Fetal Interface

The etiopathogenesis of preeclampsia, a leading hypertensive disorder of pregnancy, has been proposed to involve an abnormal circulating sex hormone profile and misexpression of placental estrogen and progesterone receptors (ER and PR, respectively). However, existing research is vastly confined to third trimester preeclamptic placentas. Consequently, the placental-uterine molecular crosstalk and the dynamic ER and PR expression pattern in the peri-conception period remain overlooked. Herein, our goal was to use the BPH/5 mouse to elucidate pre-pregnancy and early gestation Er and Pr dynamics in a preeclamptic-like uterus. BPH/5 females display low circulating estrogen concentration during proestrus, followed by early gestation hypoestrogenemia, hyperprogesteronemia, and a spontaneous preeclamptic-like phenotype. Preceding pregnancy, the gene encoding Er alpha (Erα, Esr1) is upregulated in the diestrual BPH/5 uterus. At the peak of decidualization, Esr1, Er beta (Erβ, Esr2), and Pr isoform B (Pr-B) were upregulated in the BPH/5 maternal-fetal interface. At the protein level, BPH/5 females display higher percentage of decidual cells with nuclear Erα expression, as well as Pr downregulation in the decidua, luminal and glandular epithelium. In conclusion, we provide evidence of disrupted sex hormone signaling in the peri-conception period of preeclamptic-like pregnancies, potentially shedding some light onto the intricate role of sex hormone signaling at unexplored timepoints of human preeclampsia.

Reversal of maternal obesity attenuates hypoxia and improves placental development in the preeclamptic-like BPH/5 mouse model

Background

Women with obesity have higher risk of adverse pregnancy outcomes, including preeclampsia (PE). Late-gestational hypertension, aberrant fetoplacental development, and fetal growth restriction (FGR), hallmarks of PE, are observed spontaneously in BPH/5 mice. Similar to obese preeclamptic women, BPH/5 mice have higher visceral white adipose tissue (WAT) and circulating leptin. We hypothesized that attenuation of maternal obesity and serum leptin in pregnant BPH/5 mice will improve fetoplacental development by decreasing hypoxia markers and leptin expression at the maternal-fetal interface.

Methods

To test this hypothesis, BPH/5 mice were fed ad libitum (lib) and pair-fed (PF) to C57 ad lib controls beginning at embryonic day (e) 0.5. Hypoxia-related genes, hypoxia inducible factor (Hif) 1α, stem cell factor (Scf), heme oxygenase-1 (Ho-1), leptin (Lep), and leptin receptor (LepR) were assessed in e7.5 implantation sites.

Results

BPH/5 ad lib had 1.5 to 2-fold increase in Hif1α, Scf, and Ho-1 mRNA and a greater than 3-fold increase in leptin mRNA vs. C57 that was attenuated with PF. Exogenous leptin promoted Hif1α and Ho-1 mRNA expression in e7.5 decidua in vitro. While hypoxic conditions in vitro did not change decidual leptin mRNA. Furthermore, BPH/5 PF mice demonstrated improved fetal and placental outcomes later in gestation, with greater placental vascular area by e18.5 and attenuation of FGR.

Conclusion

In conclusion, pair-feeding BPH/5 mice beginning at conception may improve placental vasculature formation via decreased leptin and hypoxia-associated markers in this model. Future investigations are needed to better determine the effect of hypoxia and leptin on pregnancy outcomes in obese pregnant women.

Alternative pathway activation in pregnancy, a measured amount "complements" a successful pregnancy, too much results in adverse events

During pregnancy, the maternal host must adapt in order to enable growth of the fetus. These changes affect all organ systems and are designed both to protect the fetus and to minimize risk to the mother. One of the most prominent adaptations involves the immune system. The semi-allogenic fetoplacental unit has non-self components and must be protected against attack from the host. This requires both attenuation of adaptive immunity and protection from innate immune defense mechanisms. One of the key innate immune players is complement, and it is important that the fetoplacental unit is not identified as non-self and subjected to complement attack. Adaptation of the complement response must, however, be managed in such a way that maternal protection against infection is not compromised. As the complement system also plays a significant facilitating role in many of the stages of a normal pregnancy, it is also important that any necessary adaptation to accommodate the semi-allogenic aspects of the fetoplacental unit does not compromise this. In this review, both the physiological role of the alternative pathway of complement in facilitating a normal pregnancy, and its detrimental participation in pregnancy-specific disorders, are discussed.

Reliability of Rodent and Rabbit Models in Preeclampsia Research

In vivo studies on the pathology of gestation, including preeclampsia, often use small mammals such as rabbits or rodents, i.e., mice, rats, hamsters, and guinea pigs. The key advantage of these animals is their short reproductive cycle; in addition, similar to humans, they also develop a haemochorial placenta and present a similar transformation of maternal spiral arteries. Interestingly, pregnant dams also demonstrate a similar reaction to inflammatory factors and placentally derived antiangiogenic factors, i.e., soluble fms-like tyrosine kinase 1 (sFlt-1) or soluble endoglin-1 (sEng), as preeclamptic women: all animals present an increase in blood pressure and usually proteinuria. These constitute the classical duet that allows for the recognition of preeclampsia. However, the time of initiation of maternal vessel remodelling and the depth of trophoblast invasion differs between rabbits, rodents, and humans. Unfortunately, at present, no known animal replicates a human pregnancy exactly, and hence, the use of rabbit and rodent models is restricted to the investigation of individual aspects of human gestation only. This article compares the process of placentation in rodents, rabbits, and humans, which should be considered when planning experiments on preeclampsia; these aspects might determine the success, or failure, of the study. The report also reviews the rodent and rabbit models used to investigate certain aspects of the pathomechanism of human preeclampsia, especially those related to incorrect trophoblast invasion, placental hypoxia, inflammation, or maternal endothelial dysfunction.

Update on Immune Mechanisms in Hypertension

The contribution of immune cells in the initiation and maintenance of hypertension is undeniable. Several studies have established the association between hypertension, inflammation, and immune cells from the innate and adaptive immune systems. Here, we provide an update to our 2017 American Journal of Hypertension review on the overview of the cellular immune responses involved in hypertension. Further, we discuss the activation of immune cells and their contribution to the pathogenesis of hypertension in different in vivo models. We also highlight existing gaps in the field of hypertension that need attention. The main goal of this review is to provide a knowledge base for translational research to develop therapeutic strategies that can improve cardiovascular health in humans.

Altered uterine angiogenesis in rats treated with a glyphosate-based herbicide

Glyphosate-based herbicides (GBHs) are the agrochemicals most used around the globe. However, they might have adverse effects on human and animal health. Previously, we showed that female rats neonatally exposed to GBHs exhibit altered expression of morphogenetic molecules and biomarkers of uterine development. We also observed a reduction in the size of implantation sites, altered expression of decidualization-related molecules, and increased post-implantation losses. Since decidualization comprises morphogenetic, biochemical and vascular changes, here we investigated the effects of neonatal GBH exposure on uterine angiogenesis in neonatal and pregnant rats. To achieve this, Wistar female rats were exposed to saline solution or GBH (2 mg glyphosate/kg-bw/day) on post-natal days (PND) 1, 3, 5 and 7. On PND8, uterine samples were collected for developmental studies. On PND90, the remaining females were mated and in the morning of gestational day (GD) 9, the implantation sites were collected. Angiogenesis-related molecules and cells involved in this process were identified and/or measured by immunohistochemistry or RT-PCR. On PND8, GBH-treated rats showed increased vascular endothelial growth factor (VEGF) expression and decreased Notch1, inducible nitric oxide synthase (iNOS) and Angiopoietin-2 (Ang2) mRNA levels. Vascular area, vessel diameter, endothelial cell proliferation, VEGF and Nestin protein expression, and VEGF, Notch1, iNOS and cyclooxygenase-2 (Cox-2) genes were downregulated in implantation sites of exposed females, while Ang2, VEGF receptor 1 and interleukin-10 (IL-10) were increased. Mast cells and macrophages were increased on PND8 and GD9 of treated rats. The increased Transforming growth factor-beta expression in the antimesometrial zone and IL-10 mRNA expression suggest that the M2 type is the predominant population of macrophages on implantation sites. In conclusion, neonatal GBH exposure alters the expression of angiogenesis-related molecules at neonatal uterine development and decidual reaction, suggesting altered vascular support. These alterations might contribute to the increased post-implantation losses observed in GBH-treated rats.

The roles of interleukin-1 receptor accessory protein in certain inflammatory conditions

Interleukin-1 receptor accessory protein (IL-1RAcP) is a member of the immunoglobulin superfamily proteins consisting of soluble and membranous isoforms. IL-1RAcP plays an essential role in the signaling of the IL-1 family cytokines such as IL-1, IL-33, and IL-36, as well as tyrosine kinases FLT3 and C-Kit. IL-1RAcP generally initiate inflammatory signaling pathway through the recruitment of signaling mediators, including MYD88 and IRAK. Chronic inflammation following prolonged signaling of cytokine receptors is a critical process in the pathogenesis of many inflammatory disorders, including autoimmunity, obesity, psoriasis, type 1 diabetes, endometriosis, preeclampsia and Alzheimer's disease. Recently IL-1RAcP aberrant signaling has been considered to play a central role in the pathogenesis of these chronic inflammatory diseases. Targeting IL-1RAcP signaling pathway that was recently considered in clinical trials related to malignancies, also indicates its potential as therapeutic target for the inflammatory and autoimmune diseases. This review summarizes the molecular structure, components associated with IL-1RAcP signaling pathways, and their involvement in the pathogenesis of different inflammatory diseases. We will also discuss the effect of IL-1RAcP inhibition for treatment proposes.

Manipulating CD4+ T Cell Pathways to Prevent Preeclampsia

Preeclampsia (PreE) is a placental disorder characterized by hypertension (HTN), proteinuria, and oxidative stress. Individuals with PreE and their children are at an increased risk of serious short- and long-term complications, such as cardiovascular disease, end-organ failure, HTN, neurodevelopmental disorders, and more. Currently, delivery is the only cure for PreE, which remains a leading cause of morbidity and mortality among pregnant individuals and neonates. There is evidence that an imbalance favoring a pro-inflammatory CD4+ T cell milieu is associated with the inadequate spiral artery remodeling and subsequent oxidative stress that prime PreE's clinical symptoms. Immunomodulatory therapies targeting CD4+ T cell mechanisms have been investigated for other immune-mediated inflammatory diseases, and the application of these prevention tactics to PreE is promising, as we review here. These immunomodulatory therapies may, among other things, decrease tumor necrosis factor alpha (TNF-α), cytolytic natural killer cells, reduce pro-inflammatory cytokine production [e.g. interleukin (IL)-17 and IL-6], stimulate regulatory T cells (Tregs), inhibit type 1 and 17 T helper cells, prevent inappropriate dendritic cell maturation, and induce anti-inflammatory cytokine action [e.g. IL-10, Interferon gamma (IFN-γ)]. We review therapies including neutralizing monoclonal antibodies against TNF-α, IL-17, IL-6, and CD28; statins; 17-hydroxyprogesterone caproate, a synthetic hormone; adoptive exogenous Treg therapy; and endothelin-1 pathway inhibitors. Rebalancing the maternal inflammatory milieu may allow for proper spiral artery invasion, placentation, and maternal tolerance of foreign fetal/paternal antigens, thereby combatting early PreE pathogenesis.

Cellular immune responses in the pathophysiology of preeclampsia

Preeclampsia, defined as new-onset hypertension accompanied by proteinuria occurring at 20 weeks of gestation or later, is a leading cause of perinatal morbidity and mortality worldwide. The pathophysiology of this major multi-systemic syndrome includes defective deep placentation, oxidative stress, endothelial dysfunction, the presence of an anti-angiogenic state, and intravascular inflammation, among others. In this review, we provide a comprehensive overview of the cellular immune responses involved in the pathogenesis of preeclampsia. Specifically, we summarize the role of innate and adaptive immune cells in the maternal circulation, reproductive tissues, and at the maternal-fetal interface of women affected by this pregnancy complication. The major cellular subsets involved in the pathogenesis of preeclampsia are regulatory T cells, effector T cells, NK cells, monocytes, macrophages, and neutrophils. We also summarize the literature on those immune cells that have been less characterized in this clinical condition, such as γδ T cells, invariant natural killer T cells, dendritic cells, mast cells, and B cells. Moreover, we discuss in vivo studies utilizing a variety of animal models of preeclampsia to further support the role of immune cells in this disease. Finally, we highlight the existing gaps in knowledge of the immunobiology of preeclampsia that require further investigation. The goal of this review is to promote translational research leading to clinically relevant strategies that can improve adverse perinatal outcomes resulting from the obstetrical syndrome of preeclampsia.

Progress in preeclampsia: the contribution of animal models

Recent advances have been made in understanding the nature of placental dysfunction causing preeclampsia, and other hypertensive disorders of pregnancy. The contribution of animal studies in the understanding of the effects of inadequate placentation on blood pressure and other target organs will be explored in this review. This will include technical aspects of animal studies in pregnancy, as well as the translation of data regarding newly discovered pathological pathways, in particular the angiogenic pathway, into targets in clinical practice.

The BPH/5 Mouse Model of Superimposed Preeclampsia Is Not a Model of HELLP Syndrome

Preeclampsia (PE) is a multisystemic disease of pregnancy affecting 2-8% of women worldwide. PE-induced liver disease is a rare but important complication of pregnancy. The pathogenesis of liver dysfunction in PE is poorly understood, but is correlated with dysregulated angiogenic, inflammatory, and hypoxic events in the early phase of placental development. Because BPH/5 mice develop the maternal and fetal hallmarks of PE during pregnancy, we hypothesized that they may also share the clinicopathologic findings of the human PE-associated hemolysis elevated liver transaminases low platelets (HELLP) syndrome. Using this model, we determined that microangiopathic hemolysis, thrombocytopenia, and elevated liver enzymes do not occur in mid to late gestation. Pregnant BPH/5 mice do not develop histologic evidence of hepatic inflammation, but they do have increased microsteatosis scores at preconception and in mid to late gestation that progress to macrosteatosis in a subset of mice in late gestation. The transcriptional upregulation of TNF-α, CXCL-10, and TLR-2 occurs in mid gestation prior to the onset of macrosteatosis. The BPH/5 female mouse is not a model of HELLP syndrome, but may be a model of fatty liver disease associated with pregnancy.

Genotypic analysis of the female BPH/5 mouse, a model of superimposed preeclampsia

Animal models that recapitulate human diseases and disorders are widely used to investigate etiology, diagnosis, and treatment of those conditions in people. Disorders during pregnancy are particularly difficult to explore as interventions in pregnant women are not easily performed. Therefore, models that allow for pre-conception investigations are advantageous for elucidating the mechanisms involved in adverse pregnancy outcomes that are responsible for both maternal and fetal morbidity, such as preeclampsia. The Blood Pressure High (BPH)/5 mouse model has been used extensively to study the pathogenesis of preeclampsia. The female BPH/5 mouse is obese with increased adiposity and borderline hypertension, both of which are exacerbated with pregnancy making it a model of superimposed preeclampsia. Thus, the BPH/5 model shares traits with a large majority of women with pre-existing conditions that predisposes them to preeclampsia. We sought to explore the genome of the BPH/5 female mouse and determine the genetic underpinnings that may contribute to preeclampsia-associated phenotypes in this model. Using a whole genome sequencing approach, we are the first to characterize the genetic mutations in BPH/5 female mice that make it unique from the closely related BPH/2 model and the normotensive background strain, C57Bl/6. We found the BPH/5 female mouse to be uniquely different from BPH/2 and C57Bl/6 mice with a genetically complex landscape. The majority of non-synonymous consequences within the coding region of BPH/5 females were missense mutations found most abundant on chromosome X when comparing BPH/5 and BPH/2, and on chromosome 8 when comparing BPH/5 to C57Bl/6. Genetic mutations in BPH/5 females largely belong to immune system-related processes, with overlap between BPH/5 and BPH/2 models. Further studies examining each gene mutation during pregnancy are warranted to determine key contributors to the BPH/5 preeclamptic-like phenotype and to identify genetic similarities to women that develop preeclampsia.

Preeclamptic Women Have Decreased Circulating IL-10 (Interleukin-10) Values at the Time of Preeclampsia Diagnosis: Systematic Review and Meta-Analysis

A key immunomodulatory cytokine, IL-10 (interleukin-10), has been shown to be dysregulated in preeclampsia, a pregnancy-specific hypertensive disorder, further characterized by multi-system involvement. However, studies have reported inconsistent findings about circulating IL-10 levels in preeclamptic versus normotensive pregnancies. The aim of the present systematic review and meta-analysis was to assess circulating IL-10 levels in preeclamptic and normotensive pregnancies at 2 time points: before, and at the time of preeclampsia diagnosis. PubMED, EMBASE, and Web of Science databases were searched to include all published studies examining circulating IL-10 levels in preeclamptic and normotensive pregnancies. Differences in IL-10 levels were evaluated by standardized mean differences. Of 876 abstracts screened, 56 studies were included in the meta-analysis. Circulating IL-10 levels were not different before the time of active disease (standardized mean differences, -0.01 [95% CI, -0.11 to 0.08]; P=0.76). At the time of active disease, women with preeclampsia (n=1599) had significantly lower IL-10 levels compared with normotensive controls (n=1998; standardized mean differences, -0.79 [95% CI, -1.22 to -0.35]; P=0.0004). IL-10 levels were lower in both early/severe and late/mild forms of preeclampsia. Subgroup analysis revealed that IL-10 measurement methodology (ELISA or multiplex bead array) and the sample type (plasma or serum) significantly influenced the observed differences, with the use of sera paired with ELISA technology providing the best distinction in IL-10 levels between preeclamptic and normotensive pregnancies. These findings support the role of decreased IL-10 levels in the pathophysiology of preeclampsia. Future studies should address the therapeutic potential of IL-10 in preeclampsia.

Essential Role of Complement in Pregnancy: From Implantation to Parturition and Beyond

The complement cascade was identified over 100 years ago, yet investigation of its role in pregnancy remains an area of intense research. Complement inhibitors at the maternal-fetal interface prevent inappropriate complement activation to protect the fetus. However, this versatile proteolytic cascade also favorably influences numerous stages of pregnancy, including implantation, fetal development, and labor. Inappropriate complement activation in pregnancy can have adverse lifelong sequelae for both mother and child. This review summarizes the current understanding of complement activation during all stages of pregnancy. In addition, consequences of complement dysregulation during adverse pregnancy outcomes from miscarriage, preeclampsia, and pre-term birth are examined. Finally, future research directions into complement activation during pregnancy are considered.

Endothelial deletion of ADAM10, a key regulator of Notch signaling, causes impaired decidualization and reduced fertility in female mice

During the initiation of pregnancy, the vasculature of the implantation site expands rapidly, yet little is known about this process or its role in fertility. Here, we report that endothelial-specific deletion of a disintegrin and metalloprotease 10 (ADAM10), an essential regulator of Notch signaling, results in severe subfertility in mice. We found that implantation sites develop until 5.5 days post conception (dpc) but are resorbed by 6.5 dpc in A10ΔEC mice. Analysis of the mutant implantation sites showed impaired decidualization and abnormal vascular patterning compared to controls. Moreover, RNA-seq analysis revealed changes in endothelial cell marker expression consistent with defective ADAM10/Notch signaling in samples from A10ΔEC mice, suggesting that this signaling pathways is essential for the physiological function of endometrial endothelial cells during early pregnancy. Our findings raise the possibility that impaired endothelial cell function could be a cause for repeated pregnancy loss (RPL) and infertility in humans.

Potential regulatory network in the PSG10P/miR-19a-3p/IL1RAP pathway is possibly involved in preeclampsia pathogenesis

Preeclampsia (PE), a pregnancy-specific disorder, is a leading cause of perinatal maternal-fetal mortality and morbidity. Impaired cell migration and invasion of trophoblastic cells and an imbalanced systemic maternal inflammatory response have been proposed as potential mechanisms of PE pathogenesis. Comparative analysis between PE placentas and normal placentas profiled differentially expressed miRNAs, lncRNAs, and mRNAs, including miR-19a-3p (miRNA), PSG10P (lncRNA), and IL1RAP (mRNA). This study was conducted to investigate their potential roles in PE pathogenesis. The expression of miR-19a-3p, PSG10P, and IL1RAP was examined in PE and normal placentas using RT-qPCR. An in vitro experiment was performed in human trophoblast HET8/SVneo and TEV-1 cells cultured in normoxic and hypoxic conditions. MiR-19a-3p targets were identified using Targetscan, miRanda, and PicTar analysis as well as luciferase reporter assays. The mouse model of PE was conducted using sFlt-1 for in vivo tests. Lower levels of miR-19a-3p, but higher levels of PSG10P and IL1RAP were observed in PE placentas and the trophoblast cells in hypoxia. Luciferase reporter assays confirmed that PSG10P and IL1RAP were both direct targets of miR-19a-3p. Exposure to hypoxia inhibited cell viability, migration, and invasion of HET8/SVneo and TEV-1 cells. Knocking out PSG10P and IL1RAP or overexpressing miR-19a-3p rescued the inhibition caused by hypoxia. In vivo experiments showed that IL1RAP promoted the expression of caspase-3, a key apoptosis enzyme, but inhibited MMP9, which is responsible for degrading the extracellular matrix, suggesting a significant role of IL1RAP in cell proliferation, migration, and invasion. miR-19a-3p, PSG10P, and IL1RAP were all found to be involved in PE pathogenesis. With a common targeting region in their sequences, a regulatory network in the PSG10P/miR-19a-3p/IL1RAP pathway may contribute to PE pathogenesis during pregnancy.

The Role of Interleukin-10 in the Pathophysiology of Preeclampsia

PURPOSE OF REVIEW

The pathophysiology of preeclampsia is complex and not entirely understood. A key feature in preeclampsia development is an immunological imbalance that shifts the maternal immune response from one of tolerance towards one promoting chronic inflammation and endothelial dysfunction. As a key regulator of immunity, IL-10 not only has immunomodulatory activity, but also directly benefits vasculature and promotes successful cellular interactions at the maternal-fetal interface. Here we focus on the mechanisms by which the dysregulation of IL-10 may contribute to the pathophysiology of preeclampsia.

RECENT FINDINGS

Dysregulation of IL-10 has been demonstrated in various animal models of preeclampsia. Decreased IL-10 production in both placenta and peripheral blood mononuclear cells has been reported in human studies, but with inconsistent results. The significance of IL-10 in preeclampsia has shifted from a key biomarker to one with therapeutic potential. As such, a better understanding of the role of this cytokine in the pathophysiology of preeclampsia is of paramount importance.

Three macrophage subsets are identified in the uterus during early human pregnancy

Macrophages are crucial for a successful pregnancy, and malfunctions of decidual macrophages correlate with adverse pregnancy outcomes, such as spontaneous abortion and preeclampsia. Previously, decidual macrophages were often thought to be a single population. In the present study, we identified three decidual macrophage subsets, CCR2-CD11cLO (CD11c^low, ~80%), CCR2-CD11cHI (CD11c^high, ~5%), and CCR2+CD11cHI (CD11c^high, 10-15%), during the first trimester of human pregnancy by flow cytometry analysis. CCR2-CD11cLO macrophages are widely distributed in the decidua, while CCR2-CD11cHI and CCR2+CD11cHI macrophages are primarily detected close to extravillous trophoblast cells according to immunofluorescence staining. According to RNA sequencing bioinformatics analysis and in vitro functional studies, these three subsets of macrophages have different phagocytic capacities. CCR2+CD11cHI macrophages have pro-inflammatory characteristics, while the CCR2-CD11cHI population is suggested to be anti-oxidative and anti-inflammatory due to its high expression of critical heme metabolism-related genes, suggesting that these two subsets of macrophages maintain an inflammatory balance at the leading edge of trophoblast invasion to facilitate the clearance of pathogen infection as well as maintain the homeostasis of the maternal-fetal interface. The present study physiologically identifies three decidual macrophage subsets. Further clarification of the functions of these subsets will improve our understanding of maternal-fetal crosstalk in the maintenance of a healthy pregnancy.

Celecoxib restores angiogenic factor expression at the maternal-fetal interface in the BPH/5 mouse model of preeclampsia

Preeclampsia (PE), a hypertensive disease of pregnancy, is a leading cause of fetal and maternal morbidity/mortality. Early angiogenic and inflammatory disturbances within the placenta are thought to underlie the development of the maternal PE syndrome and poor pregnancy outcomes. However, the exact etiology remains largely unknown. Here, we use the BPH/5 mouse model of PE to elucidate the way in which inflammation early in pregnancy contributes to abnormal expression of angiogenic factors at the maternal-fetal interface. We have previously described improvement in maternal hypertension and fetal growth restriction in this model after treatment with the anti-inflammatory cyclooxygenase-2 (Cox2) specific inhibitor celecoxib. To further characterize the mechanisms by which celecoxib improves poor pregnancy outcomes in BPH/5 mice, we determined expression of angiogenic factors and complement pathway components after celecoxib. In BPH/5 implantation sites there was increased hypoxia inducible factor-1α ( Hif1α), heme oxygenase-1 ( Ho-1), and stem cell factor ( Scf) mRNA concomitant with elevated prostaglandin synthase 2 ( Ptgs2), encoding Cox2, and elevated VEGF protein. Angiopoietin 1 ( Ang1), tunica interna endothelial cell kinase-2 receptor ( Tie2), complement factor 3 ( C3), and complement factor B ( CfB) were increased in midgestation BPH/5 placentae. Whereas BPH/5 expression levels of VEGF, Ang1, and Tie2 normalized after celecoxib, placental C3 and CfB mRNA remained unchanged. However, celecoxib did reduce the pregnancy-specific circulating soluble fms-like tyrosine kinase-1 (sFlt-1) rise in BPH/5 mice at midgestation. These data show that elevated Cox2 during implantation contributes to placental angiogenic factor imbalances in the BPH/5 mouse model of PE.

Angiogenic factor imbalance precedes complement deposition in placentae of the BPH/5 model of preeclampsia

Preeclampsia (PE), a hypertensive disorder of pregnancy, is a leading cause of maternal and fetal morbidity and mortality. Although the etiology is unknown, PE is thought to be caused by defective implantation and decidualization in pregnancy. Pregnant blood pressure high (BPH)/5 mice spontaneously develop placentopathies and maternal features of human PE. We hypothesized that BPH/5 implantation sites have transcriptomic alterations. Next-generation RNA sequencing of implantation sites at peak decidualization, embryonic day (E)7.5, revealed complement gene up-regulation in BPH/5 vs. controls. In BPH/5, expression of complement factor 3 was increased around the decidual vasculature of E7.5 implantation sites and in the trophoblast giant cell layer of E10.5 placentae. Altered expression of VEGF pathway genes in E5.5 BPH/5 implantation sites preceded complement dysregulation, which correlated with abnormal vasculature and increased placental growth factor mRNA and VEGF₁₆₄ expression at E7.5. By E10.5, proangiogenic genes were down-regulated, whereas antiangiogenic sFlt-1 was up-regulated in BPH/5 placentae. We found that early local misexpression of VEGF genes and abnormal decidual vasculature preceded sFlt-1 overexpression and increased complement deposition in BPH/5 placentae. Our findings suggest that abnormal decidual angiogenesis precedes complement activation, which in turn contributes to the aberrant trophoblast invasion and poor placentation that underlie PE.-Sones, J. L., Merriam, A. A., Seffens, A., Brown-Grant, D.-A., Butler, S. D., Zhao, A. M., Xu, X., Shawber, C. J., Grenier, J. K., Douglas, N. C. Angiogenic factor imbalance precedes complement deposition in placentae of the BPH/5 model of preeclampsia.