Pre-eclampsia affects cord blood NK cell expression of activation receptors and serum cytokine levels but not CB monocyte characteristics

Exploring the Lifeline: Unpacking the Complexities of Placental Vascular Function in Normal and Preeclamptic Pregnancies

The proper development and function of the placenta are essential for the success of pregnancy and the well-being of both the fetus and the mother. Placental vascular function facilitates efficient fetal development during pregnancy by ensuring adequate gas exchange with low vascular resistance. This review focuses on how placental vascular function can be compromised in the pregnancy pathology preeclampsia, and conversely, how placental vascular dysfunction might contribute to this condition. While the maternal endothelium is widely recognized as a key focus in preeclampsia research, this review emphasizes the importance of understanding how this condition affects the development and function of the fetal placental vasculature. The placental vascular bed, consisting of microvasculature and macrovasculature, is discussed in detail, as well as structural and functional changes associated with preeclampsia. The complexity of placental vascular reactivity and function, its mediators, its impact on placental exchange and blood distribution, and how these factors are most affected in early-onset preeclampsia are further explored. These factors include foremost lipoproteins and their cargo, oxygen levels and oxidative stress, biomechanics, and shear stress. Challenges in studying placental pathophysiology are discussed, highlighting the necessity of innovative research methodologies, including ex vivo experiments, in vivo imaging tools, and computational modeling. Finally, an outlook on the potential of drug interventions targeting the placental endothelium to improve placental vascular function in preeclampsia is provided. Overall, this review highlights the need for further research and the development of models and tools to better understand and address the challenges posed by preeclampsia and its effects on placental vascular function to improve short- and long-term outcomes for the offspring of preeclamptic pregnancies. © 2024 American Physiological Society. Compr Physiol 14:5763-5787, 2024.

TGFβ signalling: a nexus between inflammation, placental health and preeclampsia throughout pregnancy

BACKGROUND

The placenta is a unique and pivotal organ in reproduction, controlling crucial growth and cell differentiation processes that ensure a successful pregnancy. Placental development is a tightly regulated and dynamic process, in which the transforming growth factor beta (TGFβ) superfamily plays a central role. This family of pleiotropic growth factors is heavily involved in regulating various aspects of reproductive biology, particularly in trophoblast differentiation during the first trimester of pregnancy. TGFβ signalling precisely regulates trophoblast invasion and the cell transition from cytotrophoblasts to extravillous trophoblasts, which is an epithelial-to-mesenchymal transition-like process. Later in pregnancy, TGFβ signalling ensures proper vascularization and angiogenesis in placental endothelial cells. Beyond its role in trophoblasts and endothelial cells, TGFβ signalling contributes to the polarization and function of placental and decidual macrophages by promoting maternal tolerance of the semi-allogeneic foetus. Disturbances in early placental development have been associated with several pregnancy complications, including preeclampsia (PE) which is one of the severe complications. Emerging evidence suggests that TGFβ is involved in the pathogenesis of PE, thereby offering a potential target for intervention in the human placenta.

OBJECTIVE AND RATIONALE

This comprehensive review aims to explore and elucidate the roles of the major members of the TGFβ superfamily, including TGFβs, bone morphogenetic proteins (BMPs), activins, inhibins, nodals, and growth differentiation factors (GDFs), in the context of placental development and function. The review focusses on their interactions within the major cell types of the placenta, namely trophoblasts, endothelial cells, and immune cells, in both normal pregnancies and pregnancies complicated by PE throughout pregnancy.

SEARCH METHODS

A literature search was carried out using PubMed and Google Scholar, searching terms: 'TGF signalling preeclampsia', 'pregnancy TGF signalling', 'preeclampsia tgfβ', 'preeclampsia bmp', 'preeclampsia gdf', 'preeclampsia activin', 'endoglin preeclampsia', 'endoglin pregnancy', 'tgfβ signalling pregnancy', 'bmp signalling pregnancy', 'gdf signalling pregnancy', 'activin signalling pregnancy', 'Hofbauer cell tgfβ signalling', 'placental macrophages tgfβ', 'endothelial cells tgfβ', 'endothelium tgfβ signalling', 'trophoblast invasion tgfβ signalling', 'trophoblast invasion Smad', 'trophoblast invasion bmp', 'trophoblast invasion tgfβ', 'tgfβ preeclampsia', 'tgfβ placental development', 'TGFβ placental function', 'endothelial dysfunction preeclampsia tgfβ signalling', 'vascular remodelling placenta TGFβ', 'inflammation pregnancy tgfβ', 'immune response pregnancy tgfβ', 'immune tolerance pregnancy tgfβ', 'TGFβ pregnancy NK cells', 'bmp pregnancy NK cells', 'bmp pregnancy tregs', 'tgfβ pregnancy tregs', 'TGFβ placenta NK cells', 'TGFβ placenta tregs', 'NK cells preeclampsia', 'Tregs preeclampsia'. Only articles published in English until 2023 were used.

OUTCOMES

A comprehensive understanding of TGFβ signalling and its role in regulating interconnected cell functions of the main placental cell types provides valuable insights into the processes essential for successful placental development and growth of the foetus during pregnancy. By orchestrating trophoblast invasion, vascularization, immune tolerance, and tissue remodelling, TGFβ ligands contribute to the proper functioning of a healthy maternal-foetal interface. However, dysregulation of TGFβ signalling has been implicated in the pathogenesis of PE, where the shallow trophoblast invasion, defective vascular remodelling, decreased uteroplacental perfusion, and endothelial cell and immune dysfunction observed in PE, are all affected by an altered TGFβ signalling.

WIDER IMPLICATIONS

The dysregulation of TGFβ signalling in PE has important implications for research and clinical practice. Further investigation is required to understand the underlying mechanisms, including the role of different ligands and their regulation under pathophysiological conditions, in order to discover new therapeutic targets. Distinguishing between clinically manifested subtypes of PE and studying TGFβ signalling in different placental cell types holistically is an important first step. To put this knowledge into practice, pre-clinical animal models combined with new technologies are needed. This may also lead to improved human research models and identify potential therapeutic targets, ultimately improving outcomes for affected pregnancies and reducing the burden of PE.

The central role of natural killer cells in preeclampsia

Preeclampsia (PE) is a disease that is unique to pregnancy and affects multiple systems. It can lead to maternal and perinatal mortality. The precise etiology of PE is unclear. Patients with PE may have systemic or local immune abnormalities. A group of researchers has proposed that the immune communication between the fetus and mother is primarily moderated by natural killer (NK) cells as opposed to T cells, since NK cells are the most abundant immune cells in the uterus. This review examines the immunological roles of NK cells in the pathogenesis of PE. Our aim is to provide obstetricians with a comprehensive and updated research progress report on NK cells in PE patients. It has been reported that decidual NK (dNK) cells contribute to the process of uterine spiral artery remodeling and can modulate trophoblast invasion. Additionally, dNK cells can stimulate fetal growth and regulate delivery. It appears that the count or proportion of circulating NK cells is elevated in patients with or at risk for PE. Changes in the number or function of dNK cells may be the cause of PE. The Th1/Th2 equilibrium in PE has gradually shifted to an NK1/NK2 equilibrium based on cytokine production. An improper combination of killer cell immunoglobulin-like receptor (KIR) and human leukocyte antigen (HLA)-C may lead to insufficient activation of dNK cells, thereby causing PE. In the etiology of PE, NK cells appear to exert a central effect in both peripheral blood and the maternal-fetal interface. To maintain immune equilibrium both locally and systemically, it is necessary to take therapeutic measures directed at NK cells.

The roles of free iron, heme, haemoglobin, and the scavenger proteins haemopexin and alpha-1-microglobulin in preeclampsia and fetal growth restriction

BACKGROUND

Preeclampsia (PE) is a complex pregnancy syndrome characterised by maternal hypertension and organ damage after 20 weeks of gestation and is associated with an increased risk of cardiovascular disease later in life. Extracellular haemoglobin (Hb) and its metabolites heme and iron are highly toxic molecules and several defence mechanisms have evolved to protect the tissue.

OBJECTIVES

We will discuss the roles of free iron, heme, Hb, and the scavenger proteins haemopexin and alpha-1-microglobulin in pregnancies complicated by PE and fetal growth restriction (FGR).

CONCLUSION

In PE, oxidative stress causes syncytiotrophoblast (STB) stress and increased shedding of placental STB-derived extracellular vesicles (STBEV). The level in maternal circulation correlates with the severity of hypertension and supports the involvement of STBEVs in causing maternal symptoms in PE. In PE and FGR, iron homeostasis is changed, and iron levels significantly correlate with the severity of the disease. The normal increase in plasma volume taking place during pregnancy is less for PE and FGR and therefore have a different impact on, for example, iron concentration, compared to normal pregnancy. Excess iron promotes ferroptosis is suggested to play a role in trophoblast stress and lipotoxicity. Non-erythroid α-globin regulates vasodilation through the endothelial nitric oxide synthase pathway, and hypoxia-induced α-globin expression in STBs in PE placentas is suggested to contribute to hypertension in PE. Underlying placental pathology in PE with and without FGR might be amplified by iron and heme overload causing oxidative stress and ferroptosis. As the placenta becomes stressed, the release of STBEVs increases and affects the maternal vasculature.

Maternal and umbilical cord procalcitonin, high-sensitivity C-reactive protein, and interleukin-6 levels in preeclamptic and normotensive patients: A cross-sectional study

OBJECTIVES

To report maternal and umbilical vein levels of procalcitonin (PCT) in patients with preeclampsia (PE) compared to controls. As secondary aims, we measured high-sensitivity C-reactive protein (hs-CRP), and interleukin-6 (IL-6). Moreover, correlation analyses were performed between the inflammatory biomarkers and mean arterial pressure (MAP).

STUDY DESIGN

This was a single center, cross-sectional study.

MAIN OUTCOME MEASURES

After Institutional Review Board approval and written informed consent, patients with or without PE were enrolled. PCT, hs-CRP, and IL-6 levels were compared between groups using multiple linear regression models. We calculated the adjusted ratios of geometric means (aRGM) for the comparison of patients with and without PE. Correlation analysis between the inflammatory biomarkers and MAP was performed using Spearman's method.

RESULTS

A total of 156 participants were enrolled, yielding 156 venous blood samples and umbilical venous blood samples. Seventy-six patients were in the PE group, and 80 patients were in the control group. Maternal plasma and serum concentrations of PCT (aRGM 3.35 (95% confidence interval [CI]: 2.26, 4.95; p < 0.001)), hs-CRP (aRGM 1.85 (95% CI: 1.30, 2.63; p = 0.003)), and IL-6 (aRGM 1.49 (95% CI: 1.08, 2.04; p = 0.045)) were higher in the PE group. In umbilical venous samples, the concentrations of PCT (aRGM 2.54 (95% CI: 1.46, 4.44; p = 0.003)) and hs-CRP (aRGM 1.45 (95% CI: 1.13, 1.87; p = 0.012)) in the PE group were higher than the controls. No difference in umbilical venous IL-6 concentrations were detected between PE vs. control groups (aRGM 1.46; 95% CI: 1.07, 1.98; p = 0.051). There was positive correlation for both PCT and hs-CRP with MAP in maternal and umbilical venous samples. However, there was no correlation between IL and 6 and MAP in maternal or umbilical venous samples.

CONCLUSIONS

PCT levels were elevated in maternal and umbilical venous samples of patients with PE, and correlated with disease severity.

How does preeclampsia affect neonates? Highlights in the disease's immunity

INTRODUCTION

Preeclampsia (PE) is the primary obstetrical cause in one of the four perinatal deaths. Although the etiology and pathogenesis of preeclampsia is not fully known, a proinflammatory immune state prevails and can disrupt fetal hematopoiesis. Some of the effects on the newborn include neonatal thrombocytopenia, neutropenia, a reduction in T regulatory cells, and an increased cytotoxic natural killer cell profile.

METHODS

Electronic databases were searched, and defined criteria were applied to select articles for review. The review covered literature on the effects on neonatal due to maternal preeclampsia, fetal outcomes, and new treatments in research aimed at reducing morbidity and mortality of the disease.

DISCUSSION

The cytotoxic environment present in PE affects the development of fetal cell lineages. Neutropenia is observed in 50% of neonates and is correlated with mortality, although its treatment is not well-established. The enhancement in erythropoietin and the hypoxic setting present in the disease can also lead to thrombocytopenia. Per partum management includes platelet transfusion in order to avoid severe complications such as intraventricular hemorrhage. Regarding other cell lines, a cytotoxic profile is observed to be reflecting the milieu present in the mothers' bloodstream. This disruption alters the immune system response into a proinflammatory profile and can be correlated to neonatal necrotizing enterocolitis. An antiangiogenic environment is also part of the preeclampsia presentation and can be responsible for the enhancement of bronchopulmonary dysplasia observed in this population. Meanwhile, the reduction in angiogenic factors, such as vascular endothelial growth factor (VEGF), can be a protective mechanism for retinopathy of prematurity. Studies of the long-term effects of these observations are lacking, but lower neurodevelopmental scores and a higher cardiovascular risk are noted. New treatments in research propose a prevention of the disease during gestation in order to reduce the effects more efficiently in the fetus. Phosphodiesterase inhibitors, endothelin 1 receptor antagonists and manipulation of heme oxygenase-1 enzyme pathway are possible therapeutic alternatives. This review summarizes the current understanding of how preeclampsia affects neonates. As a conclusion, further studies are needed to build up a guideline to manage those effects. A research agenda is proposed.

Preeclampsia is Characterized by Fetal NK Cell Activation and a Reduction in Regulatory T Cells

Problem

Preeclampsia affects 3–17% of pregnancies worldwide and has serious consequences for both the mother and the fetus. As maternal–fetal immune tolerance is bidirectional, fetal immunopathology may play a significant role in the pathogenesis of pregnancy disorders. Nevertheless, the impact of preeclampsia on the fetal immune system is unclear.

Method of study

In this case–control study, we examined the phenotype of innate and adaptive immune cells from the cord blood of 3rd trimester babies born to healthy mothers and compared them to cord blood from 3rd trimester babies born to mothers with symptomatic preeclampsia.

Results

The ratio of CD56hi CD16− non‐activated/regulatory NK cells to CD56lo CD16+ activated/effector NK cells as well as the proportion of CD4+ T cells was significantly decreased in the cord blood of babies born to preeclamptic mothers. The percentage of FoxP3+ Treg, especially the FoxP3lo populations (resting Treg and cytokine Treg), were significantly reduced. Importantly, this reduction in FoxP3+ Treg affected the ratio of CD8+ effector T cells per FoxP3+ Treg in the cord blood of babies born to preeclamptic mothers.

Conclusion

These observations indicate that there are significant fetal immune system derangements during preeclampsia.

Genome-scale hypomethylation in the cord blood DNAs associated with early onset preeclampsia

Background

Preeclampsia is one of the leading causes of fetal and maternal morbidity and mortality worldwide. Preterm babies of mothers with early onset preeclampsia (EOPE) are at higher risks for various diseases later on in life, including cardiovascular diseases. We hypothesized that genome-wide epigenetic alterations occur in cord blood DNAs in association with EOPE and conducted a case control study to compare the genome-scale methylome differences in cord blood DNAs between 12 EOPE-associated and 8 normal births.

Results

Bioinformatics analysis of methylation data from the Infinium HumanMethylation450 BeadChip shows a genome-scale hypomethylation pattern in EOPE, with 51,486 hypomethylated CpG sites and 12,563 hypermethylated sites (adjusted P <0.05). A similar trend also exists in the proximal promoters (TSS200) associated with protein-coding genes. Using summary statistics on the CpG sites in TSS200 regions, promoters of 643 and 389 genes are hypomethylated and hypermethylated, respectively. Promoter-based differential methylation (DM) analysis reveals that genes in the farnesoid X receptor and liver X receptor (FXR/LXR) pathway are enriched, indicating dysfunction of lipid metabolism in cord blood cells. Additional biological functional alterations involve inflammation, cell growth, and hematological system development. A two-way ANOVA analysis among coupled cord blood and amniotic membrane samples shows that a group of genes involved in inflammation, lipid metabolism, and proliferation are persistently differentially methylated in both tissues, including IL12B, FAS, PIK31, and IGF1.

Conclusions

These findings provide, for the first time, evidence of prominent genome-scale DNA methylation modifications in cord blood DNAs associated with EOPE. They may suggest a connection between inflammation and lipid dysregulation in EOPE-associated newborns and a higher risk of cardiovascular diseases later in adulthood.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0052-x) contains supplementary material, which is available to authorized users.