Activation of leukocytes during the uteroplacental passage in preeclampsia

Targeting Neutrophil Extracellular Trap Formation: Exploring Promising Pharmacological Strategies for the Treatment of Preeclampsia

Neutrophils, which constitute the most abundant leukocytes in human blood, emerge as crucial players in the induction of endothelial cell death and the modulation of endothelial cell responses under both physiological and pathological conditions. The hallmark of preeclampsia is endothelial dysfunction induced by systemic inflammation, in which neutrophils, particularly through the formation of neutrophil extracellular traps (NETs), play a pivotal role in the development and perpetuation of endothelial dysfunction and the hypertensive state. Considering the potential of numerous pharmaceutical agents to attenuate NET formation (NETosis) in preeclampsia, a comprehensive assessment of the extensively studied candidates becomes imperative. This review aims to identify mechanisms associated with the induction and negative regulation of NETs in the context of preeclampsia. We discuss potential drugs to modulate NETosis, such as NF-κβ inhibitors, vitamin D, and aspirin, and their association with mutagenicity and genotoxicity. Strong evidence supports the notion that molecules involved in the activation of NETs could serve as promising targets for the treatment of preeclampsia.

Altered release of thrombomodulin and HMGB1 in the placenta complicated with preeclampsia

INTRODUCTION

Preeclampsia (PE) is a severe pregnancy complication due to placental dysfunction. Thrombomodulin (TM), a glycoprotein expressed on the trophoblast cell membrane, plays an organ-protective role in the placenta by regulating coagulation and inflammation. TM-mediated regulation of High Mobility Group Box1(HMGB1) is an essential mechanism that contributes to placental homeostasis and prevents pregnancy complications in mice. Here, we aimed to clarify the role of placental TM and HMGB1 in the pathophysiology of human PE.

METHODS AND RESULTS

In this study, maternal blood serum and placental tissue were obtained from 72 PE patients and 110 normal controls. Soluble TM(sTM) and HMGB1 levels in the maternal serum were assessed. The placental TM and HMGB1 expression levels were evaluated using immunohistochemistry and qPCR. Serum sTM and HMGB1 levels gradually increased with gestational age in normal pregnancies; however, both circulating sTM and HMGB1 levels were significantly higher in the PE group. Serum HMGB1/sTM ratio was elevated in PE patients compared to that in normal controls, which correlated positively with the clinical severity of PE. The immunohistochemistry analysis revealed the loss of TM and the increase in extranuclear HMGB1. TM mRNA expression was diminished in PE placentas, which negatively correlated with soluble fms-like tyrosine kinase-1 (sFlt-1) expression.

DISCUSSION

The increase in circulating sTM and HMGB1 could be attributed to the enhanced placental TM shedding in PE patients. The molecular events mediated by the imbalance in the placental TM and HMGB1 levels could be an underlying feature of PE; maternal serum HMGB1/sTM ratio could reflect this status.

Effects of Prenatal Cannabinoids Exposure upon Placenta and Development of Respiratory Neural Circuits

Cannabis use has risen dangerously during pregnancy in the face of incipient therapeutic use and a growing perception of safety. The main psychoactive compound of the Cannabis sativa plant is the phytocannabinoid delta-9-tetrahydrocannabinol (A-9 THC), and its status as a teratogen is controversial. THC and its endogenous analogues, anandamide (AEA) and 2-AG, exert their actions through specific receptors (eCBr) that activate intracellular signaling pathways. CB1r and CB2r, also called classic cannabinoid receptors, together with their endogenous ligands and the enzymes that synthesize and degrade them, constitute the endocannabinoid system. This system is distributed ubiquitously in various central and peripheral tissues. Although the endocannabinoid system's most studied role is controlling the release of neurotransmitters in the central nervous system, the study of long-term exposure to cannabinoids on fetal development is not well known and is vital for understanding environmental or pathological embryo-fetal or postnatal conditions. Prenatal exposure to cannabinoids in animal models has induced changes in placental and embryo-fetal organs. Particularly, cannabinoids could influence both neural and nonneural tissues and induce embryo-fetal pathological conditions in critical processes such as neural respiratory control. This review aims at the acute and chronic effects of prenatal exposure to cannabinoids on placental function and the embryo-fetal neurodevelopment of the respiratory pattern. The information provided here will serve as a theoretical framework to critically evaluate the teratogen effects of the consumption of cannabis during pregnancy.

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.

Molecular hydrogen has a positive impact on pregnancy maintenance through enhancement of mitochondrial function and immunomodulatory effects on T cells

AIMS

Molecular hydrogen (H₂) has attracted growing interest because of its implications in various diseases. However, the molecular mechanisms underlying the remarkable effect of a small amount of H₂ remain elusive. No knowledge has been available on the role of H₂ in the etiology of pregnancy disorders or its direct influence on human immune cells. Since maternal immunity, T cells in particular, plays a critical role in pregnancy maintenance. We investigated the effects of H₂ on T cells and its relation to preterm birth (PTB).

MAIN METHODS

Exhaled H₂ concentrations in pregnant women were measured and correlated with cytokine concentrations in maternal and umbilical cord blood. H₂ was added to T cells collected from healthy donors, and differentiation and proliferation were examined. Energy metabolism was also examined. H₂ was administered to mice and cytokine expression was compared.

KEY FINDINGS

Our prospective observational study revealed that maternal production of H₂ is significantly lower in pregnant women with PTB, suggesting its potential as a biomarker for predicting PTB. We found that H₂ has clear associations with several maternal cytokines, and acts as an immunomodulator by exerting mitochondrial function in human T cells. Moreover, in vivo administration of H₂ to pregnant mice regulated inflammatory responses and reduced PTB caused by T cell activation, which further supports the notion that H₂ may contribute to prolonged gestation through its immunomodulatory effect.

SIGNIFICANCE

Measuring maternal H₂-production could be a potential clinical tool in the management of PTB, and H₂ may have positive impact on pregnancy maintenance.

Neutrophil count is a useful marker to predict the severity of preeclampsia

BACKGROUND

At present, pre-eclampsia is a growing concern and still a diagnostic challenge for obstetricians.

AIMS

This study aimed to evaluate whether the relationship of second trimester of pregnancy neutrophil count differed among pregnancies with mild preeclampsia, severe preeclampsia, and healthy status and explore whether or not neutrophil count in the second trimester of pregnancy would be useful as new predictors of subsequent preeclampsia.

PATIENTS AND METHODS

This study involved 933 pregnancies from 1 January 2018 to 30 January 2021, comprising 396 healthy pregnancies, 222 pregnancies with mild preeclampsia, and 315 pregnancies with severe preeclampsia. The relationship between preeclampsia and neutrophil count was analyzed by multiple logistic regression. In addition, maternal placental tissues of three groups were immunohistochemically stained for myeloperoxidase (MPO).

RESULTS

Neutrophil count was significantly higher in pregnancies with preeclampsia (including pregnancies with mild and severe preeclampsia) than that in healthy pregnancies. The neutrophil count level was prominently higher in patients with severe preeclampsia compared with those with mild preeclampsia (p < .001). The neutrophil count level was significantly positively associated with preeclampsia after adjusting for gestational week at time of blood sampling, BMI, and age (β:1.23; 95%CI:1.09-1.36; p < .0001). In addition, MPO expressions of placental tissues in preeclamptic groups were significantly increased than these in healthy pregnant controls (p < .05).

CONCLUSIONS

Increased neutrophil count in the second trimester of pregnancy was significantly positively associated with preeclampsia. Hence, neutrophil count plays a role in predicting the severity of preeclampsia. At the same time, it may be an independent predictor of subsequent preeclampsia.Abbreviations: BMI: body mass index; MPO: myeloperoxidase.

Human placental exosomes induce maternal systemic immune tolerance by reprogramming circulating monocytes

BACKGROUND

The maternal immune system needs to tolerate the semi-allogeneic fetus in pregnancy. The adaptation occurs locally at the maternal-fetal interface as well as systemically through the maternal circulation. Failure to tolerate the paternal antigens may result in pregnancy complications, such as pregnancy loss and pre-eclampsia. However, the mechanism that regulates maternal immune tolerance, especially at the systemic level, is still an enigma. Here we report that the first-trimester placenta-derived exosomes (pEXOs) contribute to maternal immune tolerance by reprogramming the circulating monocytes.

RESULTS

pEXOs predominantly target monocytes and pEXO-educated monocytes exhibit an immunosuppressive phenotype as demonstrated by reduced expression of marker genes for monocyte activation, T-cell activation and antigen-process/presentation at the transcriptomic level. They also have a greater propensity towards M2 polarization when compared to the monocytes without pEXO treatment. The inclusion of pEXOs in a monocyte-T-cell coculture model significantly reduces proliferation of the T helper cells and cytotoxic T cells and elevates the expansion of regulatory T cells. By integrating the microRNAome of pEXO and the transcriptomes of pEXO-educated monocytes as well as various immune cell functional assays, we demonstrate that the pEXO-derived microRNA miR-29a-3p promotes the expression of programmed cell death ligand-1, a well-known surface receptor that suppresses the adaptive immune system, by down-regulation of phosphatase and tensin homolog in monocytes.

CONCLUSIONS

This is the first report to show how human pEXO directly regulates monocyte functions and its molecular mechanism during early pregnancy. The results uncover the importance of pEXO in regulating the maternal systemic immune response during early pregnancy by reprogramming circulating monocytes. The study provides the basis for understanding the regulation of maternal immune tolerance to the fetal allograft.

Pregnancy-specific expression of protease-activated receptor 1: a therapeutic target for prevention and treatment of preeclampsia?

Neutrophils extensively infiltrate maternal blood vessels in preeclampsia. This could explain why multiple organs are affected in this enigmatic disorder. Lipid peroxides produced by the placenta are probably the first factors that activate neutrophils as they circulate through the intervillous space, but then a second factor specific to pregnancy comes into play, protease-activated receptor 1. The only time neutrophils express protease-activated receptor 1 is during pregnancy. This means that neutrophils can be activated by a mechanism specific to pregnancy, that is, by proteases. Two proteases that are elevated in preeclampsia and activate protease-activated receptor 1 are matrix metalloproteinase-1 and neutrophil elastase. There is an 8-fold increase in vascular protease-activated receptor 1 expression in women with preeclampsia, and protease-activated receptor 1 is also expressed on the placenta, a pregnancy-specific tissue. The question arises if the pregnancy-specific expression of protease-activated receptor 1 is essential to the pathophysiology of preeclampsia. Protease activation of protease-activated receptor 1 in neutrophils of women with normal pregnancies causes activation of RhoA kinase. RhoA kinase phosphorylates nuclear factor-kappa B causing its translocation from the cytosol into the nucleus, increasing the expression of inflammatory genes. This signaling pathway is blocked by inhibition of either protease-activated receptor 1 or RhoA kinase activity. In contrast, neutrophils obtained from preeclamptic women are already activated, with nuclear factor-kappa B localized in the nucleus. Surprisingly, inhibition of either protease-activated receptor 1 or RhoA kinase results in an efflux of nuclear factor-kappa B from the nucleus back into the cytoplasm. Cyclooxygenase-2 seems to be a downstream mediator between protease-activated receptor 1 and RhoA kinase because aspirin inhibits the nuclear translocation of nuclear factor-kappa B and inhibits neutrophil production of superoxide, thromboxane, and tumor necrosis factor alpha. Currently, low-dose aspirin is the standard of care to prevent preeclampsia in high-risk women. Generally, the actions of low-dose aspirin are attributed to selective inhibition of maternal platelet thromboxane production. However, a recent study showed that beneficial effects extend to the placenta, where aspirin corrected the imbalance of increased thromboxane and reduced prostacyclin and oxidative stress. Selective inhibition of placental thromboxane is possible because thromboxane and prostacyclin are compartmentalized. Thromboxane is produced by trophoblast cells and prostacyclin by endothelial cells, so as aspirin crosses the placenta, its levels decline, sparing prostacyclin. Placental oxidative stress is attenuated because cyclooxygenase-2 inhibition decreases the generation of reactive oxygen species to decrease the formation of isoprostanes. The clinical manifestations of preeclampsia can be explained by protease activation of protease-activated receptor 1 in different tissues. In neutrophils, it can account for their activation and inflammatory response. In vascular tissue, protease-activated receptor 1 activation leads to enhanced vascular reactivity to angiotensin II to cause hypertension. In the placenta, it leads to oxidative stress, increased soluble fms-like tyrosine kinase, and thromboxane production. Activation of protease-activated receptor 1 on endothelial cells causes contraction, leading to edema and proteinuria, and activation on platelets leads to coagulation abnormalities. As proteases that activate protease-activated receptor 1 are elevated in the circulation of women with preeclampsia, consideration should be given to the inhibition of protease-activated receptor 1 as a treatment. Recently, The Food and Drug Administration (FDA) approved a protease-activated receptor 1 inhibitor, creating an opportunity to test whether protease-activated receptor 1 inhibition can prevent and/or treat preeclampsia, but a standard dose of aspirin might be just as effective by blocking its downstream actions.

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.

The Road to Low-Dose Aspirin Therapy for the Prevention of Preeclampsia Began with the Placenta

The road to low-dose aspirin therapy for the prevention of preeclampsia began in the 1980s with the discovery that there was increased thromboxane and decreased prostacyclin production in placentas of preeclamptic women. At the time, low-dose aspirin therapy was being used to prevent recurrent myocardial infarction and other thrombotic events based on its ability to selectively inhibit thromboxane synthesis without affecting prostacyclin synthesis. With the discovery that thromboxane was increased in preeclamptic women, it was reasonable to evaluate whether low-dose aspirin would be effective for preeclampsia prevention. The first clinical trials were very promising, but then two large multi-center trials dampened enthusiasm until meta-analysis studies showed aspirin was effective, but with caveats. Low-dose aspirin was most effective when started <16 weeks of gestation and at doses >100 mg/day. It was effective in reducing preterm preeclampsia, but not term preeclampsia, and patient compliance and patient weight were important variables. Despite the effectiveness of low-dose aspirin therapy in correcting the placental imbalance between thromboxane and prostacyclin and reducing oxidative stress, some aspirin-treated women still develop preeclampsia. Alterations in placental sphingolipids and hydroxyeicosatetraenoic acids not affected by aspirin, but with biologic actions that could cause preeclampsia, may explain treatment failures. Consideration should be given to aspirin's effect on neutrophils and pregnancy-specific expression of protease-activated receptor 1, as well as additional mechanisms of action to prevent preeclampsia.

Functional and genomic adaptations of blood monocytes to pregravid obesity during pregnancy

Pregravid obesity is associated with several adverse maternal health outcomes, such as increased risk of infection, suggesting an altered immunological state. However, the mechanisms by which obesity disrupts the pregnancy “immune clock” are still unknown. Here, we profiled circulating immune mediators, immune cell subset frequencies, and peripheral immune responses during the first and third trimesters of pregnancy in lean and obese mothers. While both Th1 and Th2 cytokines were elevated with pregnancy regardless of BMI, obese subjects had dysregulated myeloid factors in circulation at term. Pregnancy in lean subjects was associated with enhanced monocyte activation, augmented chromatin accessibility at inflammatory loci, and heightened responses to LPS. Pregravid obesity disrupted this trajectory, resulting in a lack of transcriptional, epigenetic, and metabolic changes strongly suggesting a skewing toward innate immune tolerance. These findings provide novel insight into the increased susceptibility to infections in women with obesity during pregnancy and following cesarean delivery.

•

Pregnancy is associated with activation and enhanced responses of monocytes

•

Heightened monocyte response is associated with epigenetic adaptions

•

Pregravid obesity leads to a state akin to LPS tolerance in monocytes

•

Pregravid obesity is associated with a lack of epigenetic and metabolic plasticity

Decidual factors and vasoactive intestinal peptide guide monocytes to higher migration, efferocytosis and wound healing in term human pregnancy

AIM

To explore the functional profile of circulating monocytes and decidual macrophages at term human pregnancy and their contribution to tissue repair upon stimulation ex vivo with decidual factors and the vasoactive intestinal peptide (VIP).

METHODS

Peripheral blood monocytes were isolated from pregnant and non-pregnant volunteers and tested in vitro with decidual explants from term placenta and VIP. The effect of VIP on decidual explants and the effect of its conditioned media on monocytes or decidual macrophages isolated by magnetic beads was carried out by RT-qPCR and ELISA for cytokines expression and release. Migration assays were performed in transwell systems. Efferocytosis was assessed in monocytes or decidual macrophages with CFSE-labelled autologous apoptotic neutrophils and quantified by flow cytometry. Monocyte and decidual macrophages wound healing capacity was evaluated using human endometrial stromal cell monolayers. Immunohistochemistry was performed in serial tissue sections of different placentas.

RESULTS

VIP is expressed in the villi as well as in trophoblast giant cells distributed within the decidua of term placenta. VIP induced the expression of antiinflmammatory markers and monocyte chemoattractant CCL2 and CCL3 in decidual tissues. Monocytes presented higher migration towards decidual explants than CD4 and CD8 cells. VIP-conditioned monocytes displayed an enhanced efferocytosis and wound healing capacity comparable to that of decidual macrophages. Moreover limited efferocytosis of pregnant women monocytes was restored by VIP-induced decidual factors.

CONCLUSION

Results show the conditioning of monocytes by decidual factors and VIP to sustain processes required for tissue repair and homeostasis maintenance in term placenta.

Preeclampsia Status Controls Interleukin-6 and Soluble IL-6 Receptor Release from Neutrophils and Endothelial Cells: Relevance to Increased Inflammatory Responses

Increased neutrophil–endothelial binding and inflammatory responses are significant pathophysiological events in the maternal vascular system in preeclampsia, a hypertensive disorder in human pregnancy. Interleukin 6 (IL-6) and its soluble receptors (soluble IL-6R (sIL-6R) and soluble gp130 (sgp130)) are critical inflammatory mediators. During pregnancy, maternal IL-6 and sgp130 levels were increased, but sIL-6R levels were decreased, in women with preeclampsia compared to normotensive pregnant women. However, little is known about differences in IL-6, sIL-6R, and sgp130 production by neutrophils and endothelial cells between normal pregnancy and preeclampsia. To study this, we isolated neutrophils and cultured human umbilical vein endothelial cells (HUVECs) from normal and preeclamptic pregnancies. Production of IL-6, sIL-6R, and sgp130 was measured. The role of placental factor(s)-mediated neutrophil production of IL-6, sIL-6R, and sgp130 was also determined by pretreating neutrophils with placental conditioned medium generated from placental villous cultures. We found that IL-6 and sgp130 were mainly produced by endothelial cells, while sIL-6R was mainly produced by neutrophils. Endothelial cells from preeclampsia produced significantly more IL-6 and sgp130, and neutrophils from preeclampsia produced significantly less sIL-6R than normal pregnancy cells. Interestingly, production of IL-6, sIL-6R, and sgp130 were time-dependently increased when neutrophils and endothelial cells were co-cultured. We also found that neutrophils from normal pregnancies produced more IL-6, but less sIL-6R, after being primed by preeclamptic-placental conditioned medium. These results demonstrated that neutrophils and endothelial cells have different capacities in producing IL-6, sIL-6R, and sgp130 between normal pregnancy and preeclampsia. These results also provide evidence that the placenta plays a role in inducing neutrophil activation in preeclampsia.

Dysfunction of complement receptors CR3 (CD11b/18) and CR4 (CD11c/18) in pre-eclampsia: a genetic and functional study

OBJECTIVE

To study genetic variants and their function within genes coding for complement receptors in pre-eclampsia.

DESIGN

A case-control study.

SETTING

Pre-eclampsia is a common vascular disease of pregnancy. The clearance of placenta-derived material is one of the functions of the complement system in pregnancy.

POPULATION

We genotyped 500 women with pre-eclamptic pregnancies and 190 pregnant women without pre-eclampsia, as controls, from the FINNPEC cohort, and 122 women with pre-eclamptic pregnancies and 1905 controls from the national FINRISK cohort.

METHODS

The functional consequences of genotypes discovered by targeted exomic sequencing were explored by analysing the binding of the main ligand iC3b to mutated CR3 or CR4, which were transiently expressed on the surface of COS-1 cells.

MAIN OUTCOME MEASURES

Allele frequencies were compared between pre-eclamptic pregnancies and controls in genetic studies. The functional consequences of selected variants were measured by binding assays.

RESULTS

The most significantly pre-eclampsia-linked CR3 variant M441K (P = 4.27E-4, OR = 1.401, 95% CI = 1.167-1.682) displayed a trend of increased adhesion to iC3b (P = 0.051). The CR4 variant A251T was found to enhance the adhesion of CR4 to iC3b, whereas W48R resulted in a decrease of the binding of CR4 to iC3b.

CONCLUSIONS

Results suggest that changes in complement-facilitated phagocytosis are associated with pre-eclampsia. Further studies are needed to ascertain whether aberrant CR3 and CR4 activity leads to altered pro- and anti-inflammatory cytokine responses in individuals carrying the associated variants, and the role of these receptors in pre-eclampsia pathogenesis.

TWEETABLE ABSTRACT

Genetic variants of complement receptors CR3 and CR4 have functional consequences that are associated with pre-eclampsia.

Proteases Activate Pregnancy Neutrophils by a Protease-Activated Receptor 1 Pathway: Epigenetic Implications for Preeclampsia

We tested a novel hypothesis that elevated levels of proteases in the maternal circulation of preeclamptic women activate neutrophils due to their pregnancy-specific expression of protease-activated receptor 1 (PAR-1). Plasma was collected longitudinally from normal pregnant and preeclamptic women and analyzed for MMP-1 and neutrophil elastase. Neutrophils were isolated for culture and confocal microscopy. Omental fat was collected for immunohistochemistry. Circulating proteases were significantly elevated in preeclampsia. Confocal microscopy revealed that tet methylcytosine dioxygenase 2 (TET2), a DNA de-methylase, and p65 subunit of NF-κB were strongly localized to the nucleus of untreated neutrophils of preeclamptic women, but in untreated neutrophils of normal pregnant women they were restricted to the cytosol. Treatment of normal pregnancy neutrophils with proteases activated PAR-1, leading to activation of RhoA kinase (ROCK), which triggered translocation of TET2 and p65 from the cytosol into the nucleus, mimicking the nuclear localization in neutrophils of preeclamptic women. IL-8, an NF-κB-regulated gene, increased in association with TET2 and p65 nuclear localization. Co-treatment with inhibitors of PAR-1 or ROCK prevented nuclear translocation and IL-8 did not increase. Treatment of preeclamptic pregnancy neutrophils with inhibitors emptied the nucleus of TET2 and p65, mimicking the cytosolic localization of normal pregnancy neutrophils. Expression of PAR-1 and TET2 were markedly increased in omental fat vessels and neutrophils of preeclamptic women. We conclude that elevated levels of circulating proteases in preeclamptic women activate neutrophils due to their pregnancy-specific expression of PAR-1 and speculate that TET2 DNA de-methylation plays a role in the inflammatory response.

Mitochondrial function in immune cells in health and disease

One of the main functions of mitochondria is production of ATP for cellular energy needs, however, it becomes more recognized that mitochondria are involved in differentiation and activation processes of immune cells. Upon activation, immune cells have a high need for energy. Immune cells have different strategies to generate this energy. In pro-inflammatory cells, such as activated monocytes and activated T and B cells, the energy is generated by increasing glycolysis, while in regulatory cells, such as regulatory T cells or M2 macrophages, energy is generated by increasing mitochondrial function and beta-oxidation. Except for being important for energy supply during activation, mitochondria also induce immune responses. During an infection, they release mitochondrial danger associated molecules (DAMPs) that resemble structures of bacterial derived pathogen associated molecular patterns (PAMPs). Such mitochondrial DAMPS are for instance mitochondrial DNA with hypomethylated CpG motifs or a specific lipid that is only present in prokaryotic bacteria and mitochondria, i.e. cardiolipin. Via release of such DAMPs, mitochondria guide the immune response towards an inflammatory response against pathogens. This is an important mechanism in early detection of an infection and in stimulating and sustaining immune responses to fight infections. However, mitochondrial DAMPs may also have a negative impact. If mitochondrial DAMPs are released by damaged cells, without the presence of an infection, such as after a trauma, mitochondrial DAMPs may induce an undesired inflammatory response, resulting in tissue damage and organ dysfunction. Thus, immune cells have developed mechanisms to prevent such undesired immune activation by mitochondrial components. In the present narrative review, we will describe the current view of mitochondria in regulation of immune responses. We will also discuss the current knowledge on disturbed mitochondrial function in immune cells in various immunological diseases.

In-depth characterization of monocyte subsets during the course of healthy pregnancy

Pregnancy represents an immunological challenge for the maternal immune system. Pregnancy augments innate immune responses, and particularly monocytes contribute to maintaining the balance between pro- and anti-inflammatory immune responses required for the successful sequence of distinct immunological phases throughout pregnancy. Nonetheless, studies that focus on the heterogeneity of monocytes and analyze the alteration of monocyte subsets in a longitudinal approach throughout healthy pregnancies have remained scarce. In this study, we characterized the gradual phenotypic changes of monocyte subsets and the secretory potential of bulk monocytes in peripheral blood mononuclear cells of healthy pregnant women from a population-based prospective birth cohort study. Blood samples at predefined time points were analyzed using flow cytometry for in-depth characterization of monocyte subsets, which confirmed a shift from classical towards intermediate monocytes throughout pregnancy. Principal component analysis revealed characteristic phenotypic changes on monocyte subsets, especially on the intermediate monocyte subset, throughout pregnancy. Pregnancy-related hormones were measured in serum and β-human chorionic gonadotropin levels were significantly associated with expression of CD11b, CD116 and CCR2 on monocyte subsets. TLR4 and TLR7/8 stimulation of monocytes furthermore showed reduced polycytokine production towards the end of pregnancy. These data provide a comprehensive overview of phenotypic changes and secretory potential of monocytes in healthy pregnant women and establish a selective contribution of different monocyte subsets to healthy pregnancy. The results from this study therefore build a basis for future comparisons and evaluation of women with adverse pregnancy outcomes.

Endometrial Cancer Immune Escape Mechanisms: Let Us Learn From the Fetal-Maternal Interface

The immune escape mechanisms at the base of tumor progression in endometrial cancer mimic immune tolerance mechanisms occurring at the maternal-fetal interface. The biological and immunological processes behind the maternal-fetal interface are finely tuned in time and space during embryo implantation and subsequent pregnancy stages; conversely, those behind cancer progression are often aberrant. The environment composition at the maternal-fetal interface parallels the pro-tumor microenvironment identified in many cancers, pointing to the possibility for the use of the maternal-fetal interface as a model to depict immune therapeutic targets in cancer. The framework of cancer environment signatures involved in immune adaptations, precisely timed in cancer progression, could reveal a specific "immune clock" in endometrial cancer, which might guide clinicians in patient risk class assessment, diagnostic workup, management, surgical and therapeutic approach, and surveillance strategies. Here, we review studies approaching this hypothesis, focusing on what is known so far about oncofetal similarities in immunity with the idea to individualize personalized immunotherapy targets, through the downregulation of the immune escape stage or the reactivation of the pro-inflammatory processes suppressed by the tumor.

The Role of Macrophages in Oocyte Donation Pregnancy: A Systematic Review

The embryo of an oocyte donation (OD) pregnancy is completely allogeneic to the mother, which leads to a more serious challenge for the maternal immune system to tolerize the fetus. It is thought that macrophages are essential in maintaining a healthy pregnancy, by acting in immunomodulation and spiral arterial remodeling. OD pregnancies represent an interesting model to study complex immunologic interactions between the fetus and the pregnant woman since the embryo is totally allogeneic compared to the mother. Here, we describe a narrative review on the role of macrophages and pregnancy and a systematic review was performed on the role of macrophages in OD pregnancies. Searches were made in different databases and the titles and abstracts were evaluated by three independent authors. In total, four articles were included on OD pregnancies and macrophages. Among these articles, some findings are conflicting between studies, indicating that more research is needed in this area. From current research, we could identify that there are multiple subtypes of macrophages, having diverse biological effects, and that the ratio between subtypes is altered during gestation and in aberrant pregnancy. The study of macrophages’ phenotypes and their functions in OD pregnancies might be beneficial to better understand the maternal-fetal tolerance system.

Microbiota Induced Changes in the Immune Response in Pregnant Mice

Pregnancy is associated with adaptations of the immune response and with changes in the gutmicrobiota. We hypothesized the gut microbiota are involved in inducing (part of) the immunological adaptations during pregnancy. To test this hypothesis, we collected feces from pregnant conventional mice before and during pregnancy (days 7, 14, and 18) and microbiota were measured using 16S RNA sequencing. At day 18, mice were sacrificed and splenic (various Th cell populations) and blood immune cells (monocyte subsets) were measured by flow cytometry. The data were compared with splenic and blood immune cell populations from pregnant (day 18) germfree mice and non-pregnant conventional and germfree mice. Finally, the abundances of the individual gut bacteria in the microbiota of each conventional pregnant mouse were correlated to the parameters of the immune response of the same mouse. The microbiota of conventional mice were significantly different at the end of pregnancy (day 18) as compared with pre-pregnancy (Permanova, p < 0.05). The Shannon index was decreased and the Firmicutes/Bacteroidetes ratio was increased (Friedman followed by Dunn's test, p < 0.05), while abundances of various species (such as Allobaculum stercoricanis, Barnesiella intestihominis, and Roseburia faecis) were significantly different at day 18 compared with pre-pregnancy. In pregnant conventional mice, the percentage of Th1 cells was decreased, while the percentages of Treg cells and Th2 cells were or tended to be increased vs. non-pregnant mice. In germfree mice, only the percentage of Th1 cells was decreased in pregnant vs. non-pregnant mice, with no effect of pregnancy on Treg and Th2 cells. The percentages of monocyte subsets were affected by pregnancy similarly in conventional and germfree mice. However, the activation status of monocytes (expression of CD80 and MHCII) was affected by pregnancy mainly in conventional mice, and not in germfree mice. Correlation (Spearman's coefficient) of pregnancy affected microbiota with pregnancy affected immune cells, i.e., immune cells that were only affected differently in conventional mice and germfree mice, showed 4 clusters of bacteria and 4 clusters of immune cells, some of these clusters were correlated with each other. For instance, the microbiota in cluster 1 and 2 (in which there were various short chain fatty acid producing microbiota) are positively correlated with immune cells in cluster B, containing Treg cells and Th2 cells. Microbiota and immune cells are affected by pregnancy in mice. The different immunological adaptations to pregnancy between conventional and germfree mice, such as the increase in Treg and tendency to an increase in Th2 cells in conventional pregnant mice only, may suggest that the microbiota may play a role in adapting the maternal immune response to pregnancy.

Immune imbalance is associated with the development of preeclampsia

Preeclampsia (PE) is characterized by hypertension and proteinuria. It affects about 5% to 8% of pregnancies and causes maternal and perinatal mortality and morbidity. The immune imbalance and excessive inflammatory response play vital roles in the pathogenesis of PE.In this study, we performed a case-control study to investigate the levels of cytokines, chemokines and adhesion molecules in serum and placenta of normal pregnant and PE women by Bio-Plex multiplex immunoassay and immunohistochemistry. In addition, we explored the phenotypes of monocyte and macrophage in peripheral blood and placentas in 2 groups by using flow cytometry analysis and immunohistochemistry.Our results show that pro-inflammatory factors, including interleukin-1β (IL-1β), IL-6, IL-7, IL-8, IL-17a, monocyte chemotactic protein 1 (MCP -1), and macrophage inflammatory protein 1β (MIP-1β) were significantly increased in serum of women with PE compared with controls. In addition, we detected that IL-1β, IL-6, and MCP-1 were also increased in placentas of women with PE. We further revealed that peripheral blood monocytes showed a pro-inflammatory M1-like phenotype in women with PE. Consistently, M1 macrophage infiltration was increased in placenta of women with PE compared to that of normal pregnant women.Our results demonstrated that immune imbalance promotes an inflammatory state during PE and it may be a potential therapeutic possibility for the management of PE.

HtrA4 may play a major role in inhibiting endothelial repair in pregnancy complication preeclampsia

Preeclampsia (PE) is a life-threatening complication of human pregnancy with no effective treatment other than premature delivery. It is hallmarked by systemic endothelial injury/dysfunction which is believed to be caused by abnormal levels/types of placenta-derived factors that are circulating in the maternal blood. Emerging evidence suggests that endothelial repair is also dysregulated in PE, as circulating endothelial progenitor cells (EPCs) critical for endothelial regeneration are reduced in number and functionality. However, the underlying mechanisms are poorly understood. HtrA4 is a placenta-specific protease that is secreted into the circulation and significantly elevated in early-onset PE. Here we investigated the impact of HtrA4 on endothelial proliferation and repair. We demonstrated that high levels of HtrA4 halted endothelial cell proliferation and significantly down-regulated a number of genes that are critical for cell cycle progression, including CDKN3, BIRC5, CDK1 and MKI67. Furthermore, HtrA4 significantly inhibited the proliferation of primary EPCs isolated from term human umbilical cord blood and impeded their differentiation into mature endothelial cells. Our data thus suggests that elevated levels of HtrA4 in the early-onset PE circulation may impair endothelial cell repair, not only by halting endothelial cell proliferation, but also by inhibiting the proliferation and differentiation of circulating EPCs.

High levels of HtrA4 detected in preeclamptic circulation may disrupt endothelial cell function by cleaving the main VEGFA receptor KDR

Systemic endothelial dysfunction is a key characteristic of preeclampsia (PE), which is a serious disorder of human pregnancy. We have previously reported that high-temperature requirement factor (Htr)A4 is a placenta-specific protease that is secreted into the maternal circulation and significantly up-regulated in PE, especially early-onset PE. We have also demonstrated that high levels of HtrA4 detected in the early onset PE circulation induce endothelial dysfunction in HUVECs. In the current study, we investigated whether HtrA4 could cleave the main receptor of VEGFA, the kinase domain receptor (KDR), thereby inhibiting VEGFA signaling. We first demonstrated that HtrA4 cleaved recombinant KDR in vitro. We then confirmed that HtrA4 reduced the level of KDR in HUVECs and inhibited the VEGFA-induced phosphorylation of Akt kinase, which is essential for downstream signaling. Further functional studies demonstrated that HtrA4 prevented the VEGFA-induced tube formation in HUVECs and dose-dependently inhibited the VEGFA-induced angiogenesis in explants of mouse aortic rings. These data strongly suggest that high levels of HtrA4 in the maternal circulation could cleave the main receptor of VEGFA in endothelial cells to induce a wide-spread impairment of angiogenesis. Our studies therefore suggest that HtrA4 is a potential causal factor of early onset PE.-Wang, Y., La, M., Pham, T., Lovrecz, G. O., Nie, G. High levels of HtrA4 detected in preeclamptic circulation may disrupt endothelial cell function by cleaving the main VEGFA receptor KDR.

Increased Neutrophil Activation and Plasma DNA Levels in Patients with Pre-Eclampsia

Pre-eclampsia (PE) is a chronic inflammatory disease in pregnancy, which is associated with enhanced blood coagulation and high thrombotic risk. To date, the mechanisms underlying such an association are not fully understood. Previous studies reported high levels of plasma deoxyribonucleic acid (DNA) in PE women, but the cellular source of the circulation DNA remains unknown. In this study, we tested the hypothesis that activated neutrophils undergoing cell death, also called NETosis, may be responsible for the elevated plasma DNA levels in PE women. We analysed plasma samples from non-pregnant, normal pregnant and PE women and found high levels of double-stranded DNA, myeloperoxidase (an abundant neutrophil granular enzyme) and histones (the major nucleosome proteins) in PE-derived samples, indicating increased NETosis in the maternal circulation. The high plasma DNA levels positively correlated with enhanced blood coagulation in PE women. When isolated neutrophils from normal individuals were incubated with PE-derived plasma, an elevated NETosis-stimulating activity was detected. Further experiments showed that endothelial micro-particles, but not soluble proteins, in the plasma were primarily responsible for the NETosis-stimulating activity in PE women. These results indicate that circulating micro-particles from damaged maternal endothelium are a potent stimulator for neutrophil activation and NETosis in PE women. Given the pro-coagulant and pro-thrombotic nature of granular and nuclear contents from neutrophils, enhanced systemic NETosis may represent an important mechanism underlying the hyper-coagulability and increased thrombotic risk in PE.

Low-stress Microfluidic Density-gradient Centrifugation for Blood Cell Sorting

Density gradient centrifugation exploits density differences between different blood cells to accomplish separation of peripheral blood mononuclear cells (PBMCs) from polymorphonuclear (PNM) cells, and erythrocytes or red blood cells (RBCs). While density gradient centrifugation offers a label-free alternative avoiding the use of harsh lysis buffers for blood cell isolation, it is a time-consuming and labor-intensive process during which blood cells are subject to high-levels of centrifugal force that can artifactually activate cells. To provide a low-stress alternative to this elegant method, we miniaturized and automated this process using microfluidics to ensure continuous PBMCs isolation from whole blood while avoiding the exposure to high-levels of centrifugal stress in a simple flow-through format. Within this device, a density gradient is established by exploiting laminar flow within microfluidic channels to layer a thin stream of blood over a larger stream of Ficoll. Using this approach we demonstrate successful isolation of PBMCs from whole blood with preservation of monocytes and different lymphocyte subpopulations similar to that seen with conventional density gradient centrifugation. Evaluation of activation status of PBMCs isolated using this technique shows that our approach achieves minimal isolation process induced activation of cells in comparison to conventional lysis or density gradient centrifugation. This simple, automated microfluidic density gradient centrifugation technique can potentially serve as tool for rapid and activation-free technique for isolation of PBMCs from whole blood for point-of-care applications.

Distribution of monocyte subsets and polarization in preeclampsia and intrauterine fetal growth restriction

AIM

Monocytes are likely to play a significant role in the pathogenesis of preeclampsia (PE) and intrauterine fetal growth restriction (IUGR), given their role in homeostasis and tissue repair. Our aim was to study the gestational changes in monocytes in normal pregnancy and to determine whether monocyte subsets and phenotype are altered in pregnancy complications, such as PE and IUGR.

METHODS

A prospective cross-sectional case-control study was conducted. Pregnant women between 24 and 40 weeks of gestation (n = 54) were recruited and classified into four clinical groups of normal pregnancy, PE, IUGR and PE + IUGR. The maternal monocyte subsets classical, intermediate and nonclassical were compared for each clinical group. Monocyte polarization towards M1 (inflammatory) and M2 (repair) phenotypes was assessed by surface expression of CD86 and CD163 ratio, using flow cytometry.

RESULTS

The classical monocytes were reduced and intermediate monocyte elevated compared to normal pregnancy in PE, IUGR and PE + IUGR in gestations <37 weeks and IUGR in 26-40 weeks. CD163 expression was increased and CD86/CD163 ratio decreased in IUGR compared to normal pregnancy for all subsets. Nonclassical monocyte counts and CD163 expression increased with advancing gestation in normal pregnancy.

CONCLUSION

These results show for the first time, a shift towards increased intermediate maternal monocyte subtype in IUGR and in preterm PE as well as skewing of maternal peripheral monocytes (all subsets) towards M2 phenotype in pregnancies complicated by IUGR.

Changes in intestinal gene expression and microbiota composition during late pregnancy are mouse strain dependent

Hormones and placental factors are thought to underlie the maternal immunological changes during pregnancy. However, as several intestinal microbiota are linked to immune modulations, we hypothesized that the intestinal microbiota are altered during pregnancy in favor of species associated with pregnancy associated immune modulations. We studied the fecal microbiota composition (MITchip) and intestinal and peripheral immune cells (microarray and flow cytometry) in pregnant and non-pregnant C57BL/6 and BALB/c mice. Pregnancy influenced intestinal microbiota diversity and composition, however in a mouse strain dependent way. Pregnant BALB/c mice had, among others, a relative higher abundance of Lactobacillus paracasei et rel., Roseburia intestinalis et rel. and Eubacterium hallii et rel., as compared to non-pregnant BALB/c mice, while the microbiota composition in B6 mice hardly changed during pregnancy. Additionally, intestinal immunological pathways were changed during pregnancy, however again in a mouse strain dependent way. Correlations between various bacteria and immunological genes were observed. Our data do support a role for the microbiome in changing immune responses in pregnancy. However, other factors are also involved, such as for instance changes in SCFA or changes in sensitivity to bacteria, since although immunological changes are observed in B6 mice, hardly any changes in microbiota were found in this strain. Follow up studies are needed to study the exact relationship between these parameters.

Control of the inflammatory response during pregnancy: potential role of VIP as a regulatory peptide

A network of cell-cell communications through contact and soluble factors supports the maternal-placental interaction and provides a suitable environment for fetal growth. Trophoblast cells take center stage at these loops: they interact with maternal leukocytes to sustain the varying demands of gestation, and they synthesize hormones, cytokines among other factors that contribute to the maintenance of immune homeostasis. Here, we discuss vasoactive intestinal peptide (VIP) and its potential as a regulatory neuropeptide in pregnancy. VIP is synthesized by trophoblast cells; it regulates trophoblast cell function and interaction with the major immune cell populations present in the pregnant uterus. VIP activity produces an anti-inflammatory microenvironment by modulating the functional profile of monocytes, macrophages, and regulatory T cells. Trophoblast VIP inhibits neutrophil extracellular trap formation and accelerates neutrophil apoptosis, enabling their silent clearance by phagocytic cells. The effects of VIP on the trophoblast-immune interaction are consistent with its regulatory role throughout pregnancy for immune homeostasis maintenance. These observations may provide new clues for pharmacological targeting of pregnancy complications associated with exacerbated inflammation.

Cardiac myeloperoxidase activity is elevated in hypertensive pregnant rats

Myeloperoxidase (MPO) is released from activated neutrophils. The inflammation in preeclampsia was found to be associated with endothelial dysfunction. We hypothesized that cardiac and circulating MPO levels are elevated in hypertensive pregnancy. Systolic and diastolic blood pressure and heart rate were measured on pregnancy days 14, 16, 18 and 20 in normal pregnant and hypertensive pregnant rats. Left and right ventricle weights, the number of viable fetuses, litter size, fetal and placenta weights were recorded on gestational day 21. Circulating and cardiac MPO activities, soluble fms-like tyrosine kinase-1 (sFlt-1) and vascular endothelial growth factor (VEGF) and nitric oxide (NO) were detected. The results showed increases in cardiac (left, but not right ventricle) and circulating MPO activities, and concomitantly lower number of viable fetuses, litter size, and fetal and placenta weights, and decreases in NO in hypertensive pregnant rats. Also, the increases in circulating sFlt-1 and VEGF were found in hypertensive pregnant group. In conclusion, maternal and fetal detrimental changes along with increases in circulating sFlt-1 and VEGF in hypertensive pregnancy may be associated with increases in cardiac and circulating MPO activities, confirming the causative role of inflammatory response in preeclampsia.

Are neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), and/or mean platelet volume (MPV) clinically useful as predictive parameters for preeclampsia?

OBJECTIVE

Preeclampsia (PE) is a severe pregnancy complication with significant maternal and neonatal morbi-mortality resulting in high health care costs. Prevention, mainly based on the administration of acetylsalicylic acid, is only possible if timely identification of high-risk patients can be realized in an easy, nonexpensive, and widely available method. This paper explores the clinical usability of neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), and/or mean platelet volume (MPV) in discriminating between women that will and those that will not develop PE.

STUDY DESIGN

Demographic data and laboratory results were retrospectively collected and compared in 2050 pregnant women (164 PE and 1886 controls) between 1 January 2014 and 31 January 2016.

RESULTS

In the PE group, gravidity, parity, gestational age, and birth weight were significantly lower compared to the control group. Before the 20th pregnancy week, MPV was significantly elevated in the PE group compared to the controls (p = .006), hence analysis revealed an optimal cut-off point of 8.15 (sensitivity 66.7%, specificity 56.3%) for predicting PE. At the end of pregnancy, NLR and MPV appeared to be higher and PLR lower in the PE group compared to the controls, which strengthens the current knowledge on the pathogenesis of PE.

CONCLUSIONS

MPV is significantly elevated in the first half of pregnancy in women who later develop PE and might therefore be implemented in combination with other parameters in a PE prediction model.

Multiple Soluble TGF-β Receptors in Addition to Soluble Endoglin Are Elevated in Preeclamptic Serum and They Synergistically Inhibit TGF-β Signaling

CONTEXT

Preeclampsia (PE) can be classified into early-onset (<34 weeks of gestation) and late-onset (>34 weeks of gestation) subtypes. Soluble endoglin, an auxiliary receptor for transforming growth factor (TGF)-β ligands, is increased in PE circulation and believed to inhibit TGF-β action by sequestering the ligands. However, soluble endoglin, with a low affinity to TGF-β ligands, has been demonstrated to have little effect by itself on TGF-β action.

OBJECTIVES

We examined whether multiple soluble TGF-β receptors are elevated in PE circulation and whether they synergistically block TGF-β signaling.

DESIGN

TGF-β receptors were measured using enzyme-linked immunosorbent assay in sera collected from preeclamptic pregnancies and gestation-age-matched controls. TGF-β signaling was assessed using an in vitro bioassay and a tube formation assay.

RESULTS

TGF-β type I, II, and III receptors were all identified in pregnant serum; all were substantially elevated in early-onset but not late-onset PE. Endoglin was increased in both subtypes. At the greatest concentrations detected in PE, none of these soluble TGF-β receptors alone, including endoglin, inhibited TGF-β signaling. However, when all four soluble receptors were present, signaling of both TGF-β1 and TGF-β2 was substantially reduced. Removal of any one of these soluble receptors alleviated TGF-β1 inhibition; however, removal of soluble TGFβRIII was necessary to relieve TGF-β2 inhibition.

CONCLUSIONS

Multiple soluble TGF-β receptors are present in pregnant circulation and elevated in early-onset PE; they synergistically inhibit TGF-β signaling, which might be more likely to occur in early-onset than late-onset PE. Reducing soluble TGFβRIII, rather than endoglin, would be more effective in alleviating the inhibition of both TGF-β1 and TGF-β2 signaling in PE.

Tissue factor activity in women with preeclampsia or SGA: a potential explanation for the excessive thrombin generation in these syndromes

OBJECTIVE

The aim of this study was to determine whether the activity of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in the plasma of women with preeclampsia (PE) and small for gestational age (SGA) neonate differ from that of normal pregnant women and whether they are related to specific placental lesions.

METHODS

This cross-sectional study included the following groups: (1) normal pregnancy (n = 68); (2) PE (n= 128); and (3) SGA (n = 56). Maternal plasma TF and TFPI activity was determined with chromogenic assays.

RESULTS

(1) The median maternal plasma TF activity, but not TFPI activity, differed among the study groups (p < .0001 and p = .4, respectively); (2) patients with PE had a higher median maternal plasma TF activity than women with normal pregnancies (p < .0001) and mothers with SGA fetuses (p = .002); (3) among patients with PE, those with distal villous hypoplasia had a higher median maternal TF activity than those without these placental lesions (p = .018); and (4) following adjustment for confounding variables, maternal plasma TF and TFPI activity were not associated with an SGA neonate.

CONCLUSIONS

Plasma TF activity is higher in women with PE than in those with SGA or normal pregnancies. We propose that these changes may be responsible, at least in part, for the increased in-vivo thrombin generation observed in this obstetrical syndrome.

The Distribution of Activation Markers and Selectins on Peripheral T Lymphocytes in Preeclampsia

Introduction

Impaired maternal immune tolerance resulting in systemic inflammation plays a pivotal role in the pathogenesis of preeclampsia. Phenotypical changes of monocytes and neutrophil granulocytes have already been studied in preeclampsia, and some studies also included T lymphocyte activation markers; however, the results are controversial and a comprehensive analysis of activation markers is lacking. The characteristics of cellular adhesion molecules in preeclampsia are yet to be described.

Material and Methods

Peripheral blood samples of 18 preeclamptic patients and 20 healthy pregnant women in the third trimester were evaluated using flow cytometry to characterize the cell surface expression of T lymphocyte activation markers and selectins.

Results

We found an elevated ratio of HLA-DR and CD122-, CD62E-, and CD62L-expressing cells among the CD4+ T lymphocytes in PE in comparison to healthy pregnancy. No alterations were found in the prevalence of CD69-, CD25-, and CD62P-expressing lymphocytes and CD11c-expressing monocytes.

Conclusions

Our findings support the role of activated T lymphocytes and specific cell adhesion molecules in the pathogenesis of preeclampsia.

Trophoblast cells inhibit neutrophil extracellular trap formation and enhance apoptosis through vasoactive intestinal peptide-mediated pathways

STUDY QUESTION

Do human trophoblast cells modulate neutrophil extracellular trap (NET) formation, reactive oxygen species (ROS) synthesis and neutrophil apoptosis through mechanisms involving vasoactive intestinal peptide (VIP)?

SUMMARY ANSWER

Trophoblast cells inhibited NET formation and ROS synthesis and enhanced neutrophil apoptosis through VIP-mediated pathways in a model of maternal-placental interaction.

WHAT IS KNOWN ALREADY

Immune homeostasis maintenance at the maternal-placental interface is mostly coordinated by trophoblast cells. Neutrophil activation and NET formation increases in pregnancies complicated by exacerbated pro-inflammatory responses. VIP has anti-inflammatory and immunosuppressant effects and is synthesized by trophoblast cells.

STUDY DESIGN, SIZE, DURATION

This is a laboratory-based observational study that sampled circulating neutrophils from 50 healthy volunteers to explore their response in vitro to factors derived from human trophoblast cells.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Peripheral blood neutrophils were isolated from healthy volunteers and tested in vitro with first trimester trophoblast cell line (Swan-71 and HTR8) conditioned media (CM) or with VIP. The effect of VIP and trophoblast CM on NET formation was assessed by co-localization of elastase and DNA by confocal microscopy, DNA release and elastase activity measurement. Neutrophil apoptosis was determined by flow cytometry or fluorescence microscopy. ROS formation was assessed by flow cytometry with a fluorescent probe. VIP silencing was performed by siRNA transfection. For phagocytosis of apoptotic neutrophils, autologous monocytes were sampled, and engulfment and cytokines were assessed by flow cytometry and ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Trophoblast CM and 10 nM VIP promoted neutrophil deactivation by preventing phorbol myristate acetate-induced NET formation and ROS synthesis while they increased neutrophil spontaneous apoptosis and reversed the anti-apoptotic effect of lipopolysaccharide (all P < 0.05 versus control). The effects of trophoblast CM were prevented by a VIP antagonist or when VIP knocked-down trophoblast cells were used (P < 0.05 versus control). Neutrophils driven to apoptosis by trophoblast CM could be rapidly engulfed by monocytes without increasing IL-12 production.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

The mechanisms of neutrophil deactivation by trophoblast VIP are based on the results obtained with neutrophils drawn from peripheral blood of healthy individuals interacting with trophoblast cell lines in vitro. These studies were designed to investigate biological processes at the cellular and molecular level; therefore, they have the limitations of studies in vitro and it is not possible to ascertain if these mechanisms operate similarly in vivo. We tested 50 neutrophil samples from healthy volunteers that have a normal variability in their responses. Cell lines derived from human trophoblast were used, and we cannot rule out a differential behavior of trophoblast cells in contact with neutrophils in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Results presented here are consistent with an active mechanism through which neutrophils in contact with trophoblast cells would be deactivated and silently cleared by decidual macrophages throughout pregnancy. They support a novel immunomodulatory role of trophoblast VIP on neutrophils at the placenta, providing new clues for pharmacological targeting of immune and trophoblast cells in pregnancy complications associated with exacerbated inflammation.

STUDY FUNDING/COMPETING INTERESTS

This work was funded by the National Agency of Sciences and Technology (PICT 2011-0144, 2014-0657 and 2013-2177) and University of Buenos Aires (UBACyT 20020130100040BA, 20020150100161BA and 20020130100744BA). The authors declare no competing interests.

High levels of HtrA4 observed in preeclamptic circulation drastically alter endothelial gene expression and induce inflammation in human umbilical vein endothelial cells

Introduction

Preeclampsia (PE) is a life-threatening pregnancy disorder characterized by wide-spread endothelial dysfunction. Placental factors circulating in the maternal blood are believed to cause endothelial dysfunction. Our previous study identified HtrA4 as a placenta-specific serine protease that is released into the maternal circulation and significantly increased in early-onset PE. In this study, we examined the impact of HtrA4 on expression of endothelial genes related to vessel biology, using human umbilical vein endothelial cells (HUVECs) as a model.

Methods

HUVECs were treated with 0 or 3 μg/ml HtrA4 (highest concentration seen in PE circulation) for 24 h and analysed by an endothelial cell biology PCR array containing 84 genes. HtrA4-induced changes were then validated by real-time RT-PCR and ELISA for time and dose dependency.

Results

High levels of HtrA4 significantly altered the expression of a range of genes related to inflammation, vaso-activity, angiogenesis, cell adhesion, platelet activation and coagulation. In particular, pro-inflammatory genes IL6, PTGS2 (COX2) and IL1B were significantly increased by HtrA4. IL6 protein in HUVEC media was also drastically increased. THBD, an anticoagulant factor reported to be increased in PE, was significantly up-regulated by HtrA4. In contrast, THBS1, which is involved in many regulatory processes of endothelial cell biology, was severely down-regulated by HtrA4.

Discussion

HtrA4 significantly increased the inflammatory responses of HUVECs, and altered their expression of a number of genes important for vessel biology. These data suggest that placenta-derived HtrA4 that is increased in PE circulation is a potential causal factor of endothelial dysfunction.

•

HtrA4 altered expression of endothelial genes involved in vessel biology.

•

HtrA4 significantly induced inflammation in endothelial cells.

•

Placental-derived HtrA4 is a potential causal factor of endothelial dysfunction.

Maternal monocytes in pregnancy and preeclampsia in humans and in rats

Monocytes are short-lived cells, arising from the bone marrow and maturing in the circulation. They play an important role in immune responses and are thought to be important for healthy pregnancy. In humans, 3 subpopulations of monocytes have been identified: classical, intermediate and non-classical monocytes. These subpopulations have different functions and phenotypical characteristics. Healthy pregnancy is characterized by a pro-inflammatory condition, with increased numbers of monocytes and monocyte activation as well as with increased numbers of intermediate monocytes and decreased numbers of classical monocytes. This may suggest monocyte maturation. Preeclampsia is an important pregnancy complication characterized by hypertension and proteinuria developing in the second half of pregnancy. The pathophysiology of preeclampsia is associated with further activation of the inflammatory response, further activation of monocytes and further monocyte maturation. In the present review we focus on the role of monocyte activation and maturation in healthy and preeclamptic pregnancy.

Activation of CD35 and CD55 in HIV associated normal and pre-eclamptic pregnant women

OBJECTIVE

The delicate balance which exists between complement activation and its regulation is altered in HIV infection and pregnancy disorders such as pre-eclampsia. Therefore, the purpose of this study was to investigate the expression of complement regulatory (Creg) proteins (CD35 and CD55) in HIV associated normal and pre-eclamptic pregnancies.

STUDY DESIGN

The total study population (n=100) consisted of normotensive pregnant (n=50) and pre-eclamptic (n=50) women. These groups were equally sub-stratified into HIV infected and uninfected groups (n=25 per group). Standard haematological tests were conducted. Flow cytometric analysis of isolated neutrophils were performed using fluorescein isothiocyanate-conjugated anti-CD35 and phycoerythrin-cyanine 5 conjugated anti-CD55.

RESULTS

HELLP syndrome characteristics of increased lactate dehydrogenase enzymes levels, low platelet counts, cell morphological abnormalities (red cell fragmentation) and anaemia were observed in 40% of the HIV infected pre-eclamptic group. Red cell fragmentation inclusive of burr cells and schistocytes were also noted. Activated partial thromboplastin time and fibrinogen differed significantly between the HIV uninfected pre-eclamptic compared to the HIV infected pre-eclamptic groups (p<0.01). Irrespective of HIV status, the mean fluorescence intensity of CD35 and CD55 were significantly higher in the pre-eclamptic compared to the normotensive pregnant (p=0.0001; p=0.0001 respectively) groups. In the pre-eclamptic groups, the expression of both CD35 and CD55 did not significantly differ between HIV infected and uninfected women (p=0.486; p=0.767 respectively).

CONCLUSIONS

This study demonstrates an up-regulation of complement regulatory proteins, CD35 and CD55 in HIV associated pre-eclamptic compared to normotensive pregnancy. This elevation of the Creg proteins is an adaptive immune response to the high complement-mediated cell lysis that occurs in HIV infection and further aggravated by the complement activated state of pre-eclampsia.

Influence of peripheral blood microparticles of pregnant women with preeclampsia on the phenotype of monocytes

Platelet- and endothelial-derived microparticles influence the phenotype of peripheral blood leukocytes and induce production of proinflammatory cytokines. The influence of blood plasma microparticles of pregnant women on the surface receptor expression on intact or activated monocytes is still unexplored. This study was carried out to test the hypothesis that peripheral blood microparticles of women with normal pregnancy and women with preeclampsia have different influence on the expression of surface molecules on monocytes. The objective of the study was to evaluate the influence of blood plasma microparticles of pregnant women on the phenotypic properties of intact and activated THP-1 monocytes. Microparticles were isolated from peripheral blood samples of nonpregnant women, healthy pregnant women, and women with preeclampsia. THP-1 cell line was used as a model of monocytes. Microparticles of nonpregnant women decreased CD18, CD49d, and CD54 expressions and increased CD11c, CD31, CD47, and vascular endothelial growth factor receptor 2 expressions. Microparticles of healthy pregnant women increased CD18, CD54, and integrin β7 expressions and decreased CD11a and CD29 expressions. Microparticles of women with preeclampsia decreased CD18 expression on tumor necrosis factor α (TNF-α)-activated ТНР-1 cells. Microparticles of nonpregnant women, women with normal pregnancy, and pregnant women with preeclampsia decreased CD181 expression on intact and TNF-α-activated THP-1 cells. Therefore, blood plasma microparticles of women with normal pregnancy and women with preeclampsia have different influences on the expression of surface molecules on THP-1 monocytes.

The role of CX3CL1 in fetal-maternal interaction during human gestation

Embryo implantation and subsequent placentation require a fine balanced fetal-maternal cross-talk of hormones, cytokines and chemokines. Amongst the group of chemokines, CX3CL1 (also known as fractalkine) has recently attracted attention in the field of reproductive research. It exists both as membrane-bound and soluble isoforms. On the basis of current experimental evidence, fractalkine is suggested to regulate adhesion and migration processes in fetal-maternal interaction at different stages of human pregnancy. Expressed by uterine glandular epithelial cells, predominantly during the mid-secretory phase of the menstrual cycle, fractalkine appears to prime the blastocyst for forthcoming implantation. After implantation, fractalkine is suggested to regulate invasion of extravillous trophoblasts by altering their expression profile of adhesion molecules. With onset of perfusion of the intervillous space at the end of first trimester, fractalkine present at the apical microvillous plasma membrane of the syncytiotrophoblast may mediate close interaction of placental villi with circulating maternal blood cells.

Complement Split Products C3a/C5a and Receptors: Are They Regulated by Circulating Angiotensin II Type 1 Receptor Autoantibody in Severe Preeclampsia?

BACKGROUND

This study measured the serum levels of complement component (C)3a and C5a and the placental expressions of C3a receptor (R) and C5aR to determine a potential correlation with circulating angiotensin II type 1 (AT1) receptor agonistic autoantibody (AT1-AA) in severe pre-eclampsia.

METHODS

A total of 118 women were recruited and divided into 2 groups: the control group (normotensive preterm pregnancies, n = 66) and severe pre-eclampsia group (n = 52). Levels of C3a, C5a and AT1-AA in serum were measured by enzyme-linked immunosorbent assay and C3aR and C5aR in placenta by Western blotting.

RESULTS

Levels of C3a, C5a and AT1-AA in serum from the severe pre-eclampsia group were significantly higher than in controls (p < 0.05). Placental expression of C3aR and C5aR in the pre-eclampsia group was lower than that in controls (p < 0.05). There were significant positive correlations between levels of C3a, C5a and AT1-AA in serum from the pre-eclampsia group (p < 0.05). In contrast, there was no correlation between C3aR and C5aR in the placenta and AT1-AA in serum in the pre-eclampsia group (p > 0.05).

CONCLUSION

Increased C3a, C5a and AT1-AA in the serum provide indirect evidence that AT1-AA-mediated activation contributes to activate complement, which is a key mechanism underlying the pathogenesis of severe pre-eclampsia.

The role of shed placental DNA in the systemic inflammatory syndrome of preeclampsia

Preeclampsia is a syndrome occurring only in pregnancy characterized by systemic maternal inflammation and associated with the presence of the placenta. How these 2 aspects of the disease are linked has been the subject of numerous theories and ideas. Recently, there has been increasing interest in DNA shed from the placenta into the maternal circulation as a potential agent initiating the inflammatory response. This review will discuss the current evidence and future directions for placental DNA as the linking factor in preeclampsia in the context of other hypotheses.

Genetic, immune and vasoactive factors in the vascular dysfunction associated with hypertension in pregnancy

INTRODUCTION

Preeclampsia (PE) is a major complication of pregnancy that could lead to maternal and fetal morbidity and mortality. The pathophysiological mechanisms of PE are not completely understood, but recent research has begun to unravel some of the potential mechanisms.

AREAS COVERED

Genetic polymorphisms and altered maternal immune response may cause impaired remodeling of the spiral arteries; a potential early defect in PE. Inadequate invasion of cytotrophoblasts into the decidua leads to reduced uteroplacental perfusion pressure (RUPP) and placental ischemia/hypoxia. Placental ischemia causes the release of biologically active factors such as anti-angiogenic factors, inflammatory cytokines, reactive oxygen species, hypoxia-inducible factors, and angiotensin II receptor autoantibodies. These vasoactive factors could cause systemic vascular endotheliosis and consequent increase in vascular resistance and blood pressure, glomerular endotheliosis causing proteinuria, cerebrovascular endotheliosis causing cerebral edema, seizures and visual disturbances, and hepatic endotheliosis, which may contribute to the manifestations of HELLP syndrome. PE-associated vascular endotheliosis causes a decrease in vasodilator mediators such as nitric oxide, prostacyclin and endothelium-derived hyperpolarizing factor, an increase in vasoconstrictors such as endothelin-1, angiotensin II and thromboxane A2, and enhanced mechanisms of vascular smooth muscle contraction such as intracellular Ca(2+), protein kinase C and Rho-kinase. Changes in matrix metalloproteinase activity and extracellular matrix cause vascular remodeling and further vasoconstriction.

EXPERT OPINION

Some of the genetic, immune and vasoactive factors involved in vascular endotheliosis could be used as biomarkers for early detection, and as potential targets for prevention and treatment of PE.

Expression profile of C19MC microRNAs in placental tissue in pregnancy-related complications

To demonstrate that pregnancy-related complications are associated with alterations in placental microRNA expression. Gene expression of 15 C19MC microRNAs (miR-512-5p, miR-515-5p, miR-516-5p, miR-517-5p, miR-518b, miR-518f-5p, miR-519a, miR-519d, miR-519e-5p, miR-520a-5p, miR-520h, miR-524-5p, miR-525, miR-526a, and miR-526b) was assessed in placental tissues, compared between groups (21 gestational hypertension [GH], 63 preeclampsia, 36 fetal growth restriction [FGR], and 42 normal pregnancies), and correlated with the severity of the disease with respect to clinical signs, delivery date, and Doppler ultrasound parameters. The expression profile of microRNAs was different between pregnancy-related complications and controls. The downregulation of 4 of 15 (miR-517-5p, miR-519d, miR-520a-5p, and miR-525), 6 of 15 (miR-517-5p, miR-518f-5p, miR-519a, miR-519d, miR-520a-5p, and miR-525), and 11 of 15 (miR-515-5p, miR-517-5p, miR-518b, miR-518f-5p, miR-519a, miR-519d, miR-520a-5p, miR-520h, miR-524-5p, miR-525, and miR-526a) microRNAs was associated with GH, FGR, and preeclampsia, respectively. Sudden onset of severe preeclampsia requiring immediate termination of gestation and mild forms of preeclampsia (persisting for several weeks) were associated with similar microRNA expression profile (downregulation of miR-517-5p, miR-520a-5p, miR-524-5p, and miR-525). In addition, miR-519a was found to be associated with severe preeclampsia. The longer the pregnancy-related disorder lasted, the more extensive was the downregulation of microRNAs (miR-515-5p, miR-518b, miR-518f-5p, miR-519d, and miR-520h). The downregulation of some C19MC microRNAs is a common phenomenon shared between GH, preeclampsia, and FGR. On the other hand, some of the C19MC microRNAs are only downregulated just in preeclampsia.