Myeloid and lymphoid dendritic cells in normal pregnancy and pre-eclampsia

The aim of our study was to estimate the populations of peripheral blood myeloid and lymphoid dendritic cells (CD1c+, BDCA-2+) and the CD1c+ : BDCA-2+ ratio in normal pregnant women and in patients with pre-eclampsia. Fifteen women in the first, second and third trimesters of normal pregnancy, and 25 patients with pre-eclampsia were included in the study. The dendritic cells were isolated from peripheral blood, stained with monoclonal antibodies against blood dendritic cell antigens (anti-CD1c, anti-BDCA-2) and estimated using the flow cytometric method. CD1c+ and BDCA-2+ dendritic cells were present in women during all trimesters of physiological pregnancy and in pre-eclamptic patients. It was observed that the numbers of dendritic cells were significantly lower in the second trimester when compared with the first and third trimesters of normal pregnancy. Furthermore, in the second trimester, CD1c+ : BDCA-2+ ratio was higher than in the other trimesters of physiological pregnancy. All populations of dendritic cells and CD1c+ : BDCA-2+ ratio did not differ in the first and third trimesters of normal pregnancy. The percentage of BDCA-2+ dendritic cells was significantly lower in pre-eclampsia in comparison with healthy women in the third trimester of physiological pregnancy, while CD1c+ : BDCA-2+ ratio was significantly higher in pre-eclamptic patients when compared with control groups. We concluded that dendritic cells may be involved in the immune regulation during physiological pregnancy. CD1c+ and BDCA-2+ cells can influence the Th2 phenomenon which is observed during physiological pregnancy. Furthermore, it seems possible that lower BDCA-2+ cells percentage and higher CD1c+ : BDCA-2+ ratio can be associated with increased Th1-type immunity in patients with pre-eclampsia.     

Altered cell kinetics in cultured placental villous explants in pregnancies complicated by pre-eclampsia and intrauterine growth restriction

Placentae in pre-eclampsia (PE) and intrauterine growth restriction (IUGR) are characterized by morphological variations, apoptosis, and syncytial shedding, features that are linked to inappropriate oxygen and inflammatory cytokines. Cell turnover within the placenta is dynamic. In this study, these cellular events have been investigated longitudinally using a placental explant model. Intrinsic variations between normal (n = 14), PE (n = 16) and IUGR pregnancies (n = 11), and their responses to oxygen (3% and 17%) and exogenous tumour necrosis alpha (TNFalpha), were recorded. Placental explants were assessed for apoptotic morphology, immunolocalization of MIB-1 (a proliferation marker), lactate dehydrogenase (a necrosis marker), and human chorionic gonadotrophin (hCG, a marker of cytotrophoblast differentiation). Explants under TNFalpha and 17% O2 revealed progressive degeneration of syncytiotrophoblast (ST) followed by restoration of hCG, localized to newly differentiated cytotrophoblasts. This differentiation was significantly enhanced in PE and IUGR. Responses to 3% O2 were similar between groups: a sharp decline in hCG and failure to recover thereafter. Exaggerated cell death was recorded in PE and IUGR explants exposed to TNFalpha and 3% O2. All significant changes in apoptosis were confined to ST and stromal compartments. Enhanced cell death was predominantly apoptotic in PE and necrotic in IUGR. 3% O2 promoted cell proliferation in normal placentae but this response was not reciprocated in PE and IUGR. Elevated hCG in PE and IUGR explants may represent a placental predisposition to differentiation in vivo. In addition, the increased susceptibility of villous components to cell death, in the absence of stimulated proliferation, may provide a powerful mechanism for aberrant or adaptive placental cell turnover in utero.     

Circulating ficolin-2 and ficolin-3 in normal pregnancy and pre-eclampsia

Ficolins are soluble molecules of the innate immune system that recognize carbohydrate molecules on microbial pathogens, apoptotic and necrotic cells. They act through two distinct routes: initiating the lectin pathway of complement activation and mediating a primitive opsonophagocytosis. In this study, we measured plasma levels of ficolin-2 and ficolin-3 in 60 pre-eclamptic patients, 60 healthy pregnant women and 59 healthy non-pregnant women by enzyme-linked immunosorbent assay (ELISA). Circulating levels of complement activation products (C4d, C3a, SC5b9), angiogenic factors (soluble fms-like tyrosine kinase-1, placental growth factor) and markers of endothelial activation (von Willebrand factor antigen), endothelial injury (fibronectin) and trophoblast debris (cell-free fetal DNA) were also determined. Plasma levels of ficolin-2 were significantly lower in healthy pregnant than in healthy non-pregnant women, while ficolin-3 levels did not differ significantly between the two groups. Furthermore, pre-eclamptic patients had significantly lower ficolin-2 and ficolin-3 concentrations than healthy non-pregnant and pregnant women. In the pre-eclamptic group, plasma ficolin-2 levels showed a significant positive correlation with serum placental growth factor (PlGF) concentrations and significant inverse correlations with serum levels of soluble fms-like tyrosine kinase-1 (sFlt-1), blood urea nitrogen and creatinine, serum lactate dehydrogenase activities, as well as with plasma VWF:antigen, fibronectin and cell-free fetal DNA concentrations. In conclusion, circulating levels of ficolin-2 are decreased in the third trimester of normal pregnancy. There is a further decrease in plasma ficolin-2 concentrations in pre-eclampsia, which might contribute to the development of the maternal syndrome of the disease through impaired removal of the trophoblast-derived material released into the maternal circulation by the hypoxic and oxidatively stressed pre-eclamptic placenta.     

Increased prevalence of IL-17-producing peripheral blood lymphocytes in pre-eclampsia

Citation
Toldi G, Rigó J Jr, Stenczer B, Vásárhelyi B, Molvarec A. Increased prevalence of IL‐17‐producing peripheral blood lymphocytes in pre‐eclampsia. Am J Reprod Immunol 2011; 66: 223–229 Problem Systemic inflammation is a dominant component in the pathogenesis of pre‐eclampsia. Besides the imbalance of Th1 and Th2 cells, alterations of the prevalence of Th17 and regulatory T cells have also been suggested to contribute to inflammation. We aimed to describe the prevalence of these four CD4 lymphocyte subtypes in pre‐eclampsia and normal pregnancy, along with that of IL‐17‐producing CD8 and NK cells. Method of study Twenty pre‐eclamptic and 22 normal pregnant women were enrolled in this study. Using flow cytometry, we determined the prevalence of IL‐17‐producing cells among the CD4, CD8 and NK cell subsets. Furthermore, we measured the prevalence of CD4+ Tregs, and Th1/Th2 cells were characterized using cell surface chemokine receptor markers. Results We demonstrated that there is a shift not only in the Th1/Th2 but also in the Th17/Treg balance favouring skewness towards a pro‐inflammatory status in pre‐eclampsia. The proportion of CD8 and NK cells that express IL‐17 was also higher in pre‐eclampsia. Conclusion The prevalence of IL‐17‐producing CD4, CD8 and NK cells is elevated in pre‐eclampsia, indicating that both the innate and adaptive arms of the immune system are involved in the development of the exaggerated maternal systemic inflammation observed in this pregnancy‐specific disorder.     

Animal models of pre-eclampsia

The cardinal features of human pre-eclampsia, hypertension and proteinuria, are mimicked in animal models. Increasingly, the accuracy of inducing 'pure' systemic endothelial dysfunction is regarded as critical in differentiating mechanisms of pre-eclampsia from other conditions which induce hypertension (e.g. glomerulonephritis, renal denervation or manipulation of the renin-angiotensin system). A recent study in baboons has identified the timing of induction of maternal endothelial damage after acute uteroplacental ischaemia (UPI). The endothelial changes in the glomerulus are indicative of a direct endothelial toxin and mimic the lesions seen in human pre-eclampsia; the extent of hypertension and proteinuria are also similar. This animal model identifies systemic and placental sFLT-1 (soluble fms-like tyrosine kinase-1) as a potential mediator of endothelial damage. This research involving primates with haemomonochorial placentas makes translation of these results to humans very compelling for understanding the mechanisms of human disease. Similar endothelial dysfunction has been identified in baboons treated with anti-inflammatory inhibitors. Similar studies in rodents have identified a relationship between angiotensin II agonistic antibodies, UPI/reduced uteroplacental perfusion pressure, angiogenic markers, and cytokines. We can now identify vasoconstrictive mediators of the hypertensive and endothelial response such as endothelin 1, the renin-angiotensin system, or other hormones such as oestrogens in primate models.     

Lethal candida sepsis associated with myeloperoxidase deficiency and pre-eclampsia

We report on a 27-year-old primipara suffering from pre-eclampsia who died within 2 days postpartum. Toxemia with disseminated intravascular coagulation (DIC) and acute renal failure had masked the symptoms of invasive candida esophagitis and disseminated candidiasis in both lungs. Candida sepsis was discovered as the cause of death at postmortem examination. Myeloperoxidase (MPO) deficiency was identified as having supported the invasive candida infection. We conclude that a combination of MPO-deficiency and gestational toxemia may indicate increased susceptibility to severe candida infections.     

Proportion of peripheral blood and decidual CD4(+) CD25(bright) regulatory T cells in pre-eclampsia

CD4(+) CD25(bright) regulatory T (T(reg)) cells have been identified as a principle regulator of tolerance during pregnancy. In the setting of pre-eclampsia, however, little is known about the dynamics of these cells. In the current study, we determined CD4(+) CD25(bright) T(reg) cells in the peripheral blood using flow cytometry and forkhead box P3 (FoxP3(+)) cells at the placental bed using immunohistochemical staining. Peripheral blood mononuclear cells (PBMC) of 38 pre-eclamptic cases (17 cases Japanese, 21 cases Polish), 40 normal late pregnancy subjects (20 subjects Japanese, 20 subjects Polish), and 21 non-pregnant healthy controls (10 subjects Japanese, 11 subjects Polish) were included. We found the percentage of CD25(bright) cells within the CD4(+) T cell population in PBMC was reduced significantly in both Japanese and Polish pre-eclamptic cases than in normal pregnancy subjects (P < 0.001) and non-pregnant healthy controls (P < 0.001). Also, the percentage of FoxP3(+) cells within CD3(+) T cells in the placental bed biopsy samples of pre-eclamptic cases were decreased compared to those in normal pregnancy subjects. These findings suggest that a decreased number of T(reg) cells was present in pre-eclampsia, and these changes might break the maternal tolerance to the fetus.     

Serum anti-carbonic anhydrase II antibodies and oxidant-antioxidant balance in pre-eclampsia

PROBLEM The aim of this study was to investigate the presence of anti-carbonic anhydrase II antibodies (anti-CA II) antibodies in pre-eclampsia and the relationships between the autoantibodies, total antioxidant capacity (TAC) and total oxidant capacity (TOC), malondialdehyde (MDA) and oxidative stres index (OSI) parameters. METHOD OF STUDY We studied 40 early and late onset pre-eclamptic patients and 40 healthy pregnant control and 39 healthy non-pregnant control subjects. Serum CA II antibodies, TAC and TOC, and MDA parameters were studied by ELISA. RESULTS The mean values for TAC, TOC, OSI, MDA, and anti-CA II were significantly increased in patients with pre-eclampsia compared to the other groups. The anti-CA II antibody levels for the pregnant control subjects were 0.129 ± 0.04 and that for the pre-eclamptic patients were 0.282 ± 0.18. In this study, any absorbance value higher than 0.136, the mean absorbance + 2 S.D. of pregnant control subjects, was defined as positive. Positive results were obtained in 29 of 40 pre-eclamptic patients (72.5%). There were significant positive correlations between serum anti-CA II antibodies and TOC, MDA levels, and OSI levels. CONCLUSION The results suggest that anti-CA II antibodies and impairment in oxidant-antioxidant balance may be involved in multifactorial etiology of pre-eclampsia.     

Interleukin‐1 family cytokines and their regulatory proteins in normal pregnancy and pre‐eclampsia

Maternal systemic inflammation is a feature of pre‐eclampsia, a condition in pregnancy characterized by hypertension and proteinuria. Pre‐eclampsia is caused by the placenta; many placental factors contribute to the syndrome's progression, and proinflammatory cytokines have been identified previously as one such mediator. The interleukin (IL)‐1 family of cytokines are key regulators of the inflammatory network, and two naturally occurring regulatory molecules for IL‐1 family cytokines, IL‐1RA and sST2, have been found previously to be elevated in maternal blood from women with pre‐eclampsia. Here we investigate more recently identified IL‐1 family cytokines and regulatory molecules, IL‐1RAcP, IL‐37, IL‐18BP, IL‐36α/β/γ/Ra and IL‐38 in pre‐eclampsia. Pregnant women have more circulating IL‐18BP and IL‐36Ra than non‐pregnant women, and sIL‐1RAcP is elevated from women with pre‐eclampsia compared to normal pregnancies. The placenta expresses all the molecules, and IL‐37 and IL‐18BP are up‐regulated significantly in pre‐eclampsia placentas compared to those from normal pregnancies. Together, these changes contribute to the required inhibition of maternal systemic cytotoxic immunity in normal pregnancy; however, in pre‐eclampsia the same profile is not seen. Interestingly, the increased circulating levels of sIL‐1RAcP and increased placental IL‐18BP and IL‐37, the latter of which we show to be induced by hypoxic damage to the placenta, are all factors which are anti‐inflammatory. While the placenta is often held responsible for the damage and clinical symptoms of pre‐eclampsia by the research community, here we show that the pre‐eclampsia placenta is also trying to prevent inflammatory damage to the mother.     

Serum granulysin is a marker for Th1 type immunity in pre-eclampsia

Recent studies suggest that pre-eclampsia is associated with a Th1 predominant state and may be considered a failure of tolerance. Granulysin is a cytotoxic granule protein of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). Recently, we developed an enzyme-linked immunosorbent assay (ELISA) system for detecting serum granulysin, and reported that serum granulysin is a useful marker to evaluate the cell-mediated immunity. In this study, we show that the serum levels of granulysin were significantly elevated in pre-eclamptic patients compared with those in normal pregnancy subjects. In addition, the serum granulysin levels in pre-eclamptic patients were well associated with mean blood pressure, percentage of peripheral blood Th1 cells and Th1/Th2 ratios. The present results suggest that the serum granulysin levels would be a useful and novel serum marker to evaluate the Th1/Th2 balance, especially Th1 type immunity in pre-eclampsia.     

Impaired decidual natural killer cell regulation of vascular remodelling in early human pregnancies with high uterine artery resistance

During human pregnancy, natural killer (NK) cells accumulate in the maternal decidua, but their specific roles remain to be determined. Decidual NK (dNK) cells are present during trophoblast invasion and uterine spiral artery remodelling. These events are crucial for successful placentation and the provision of an adequate blood supply to the developing fetus. Remodelling of spiral arteries is impaired in the dangerous pregnancy complication pre‐eclampsia. We studied dNK cells isolated from pregnancies at 9–14 weeks' gestation, screened by uterine artery Doppler ultrasound to determine resistance indices which relate to the extent of spiral artery remodelling. dNK cells were able to promote the invasive behaviour of fetal trophoblast cells, partly through HGF. Cells isolated from pregnancies with higher resistance indices were less able to do this and secreted fewer pro‐invasive factors. dNK cells from pregnancies with normal resistance indices could induce apoptotic changes in vascular smooth muscle and endothelial cells in vitro, events of importance in vessel remodelling, partly through Fas signalling. dNK cells isolated from high resistance index pregnancies failed to induce vascular apoptosis and secreted fewer pro‐apoptotic factors. We have modelled the cellular interactions at the maternal‐fetal interface and provide the first demonstration of a functional role for dNK cells in influencing vascular cells. A potential mechanism contributing to impaired vessel remodelling in pregnancies with a higher uterine artery resistance is presented. These findings may be informative in determining the cellular interactions contributing to the pathology of pregnancy disorders where remodelling is impaired, such as pre‐eclampsia. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

The role of CXC chemokine ligand 16 in physiological and pathological pregnancies

The survival and development of a semi‐allogeneic fetus during pregnancy require the involvement of a series of cytokines and immune cells. Chemokines are a type of special cytokine those were originally described as having a role in leukocyte trafficking. CXC chemokine ligand (CXCL) 16 is a member of the chemokine family, and CXC chemokine receptor (CXCR) 6 is its sole receptor. Emerging evidence has shown that CXCL16/CXCR6 is expressed at the maternal‐fetal interface, by cell types that include trophoblast cells, decidual stroma cells, and decidual immune cells (eg, monocytes, γδT cells, and natural killer T (NKT) cells). The regulation of expression of CXCL16 is quite complex, and this process involves a multitude of factors. CXCL16 exerts a critical role in the establishment of a successful pregnancy through a series of molecular interactions at the maternal‐fetal interface. However, an abnormal expression of CXCL16 is associated with certain pathological states associated with pregnancy, including recurrent miscarriage, pre‐eclampsia, and gestational diabetes mellitus (GDM). In the present review, the expression and pleiotropic roles of CXCL16 under conditions of physiological and pathological pregnancy are systematically discussed.     

Changes in systemic type 1 and type 2 immunity in normal pregnancy and pre-eclampsia may be mediated by natural killer cells

A bias of T cell immunity towards type 2 (Th2) is thought to be critical for normal pregnancy. Pathological pregnancies, such as pre-eclampsia, are characterised by cell-mediated (Th1) immune dominance. The Th1/Th2 paradigm, however, is too simplistic. Normal pregnancy is associated with a systemic inflammatory response which increases throughout gestation. This inflammatory response is exaggerated in pre-eclampsia, a syndrome of the third trimester. T helper (Th) cells are considered the primary mediators of these altered immune responses, and other T cells, i.e. T cytotoxic (Tc) cells, and lymphocytes of the innate immune system, i.e. natural killer (NK) and NKT cells, have been largely disregarded. In this study, we have used novel pan type 1 (IL-18 receptor) and pan type 2 (ST2L) lymphocyte function markers in four-colour flow cytometry to broadly characterise peripheral blood lymphocyte populations from non-pregnant, normal pregnant and pre-eclamptic women. There were no changes in the Th1/Th2 or Tc1/Tc2 cell ratios between the three groups; however, the NK1/NK2 and NKT1/NKT2 cell ratios were significantly decreased in normal pregnancy compared with non-pregnant (p <0.001 and p <0.01, respectively) and pre-eclamptic women (p <0.05). These results confirm that immunoregulation occurs in pregnancy, but suggest a dominant role of the innate rather than the adaptive immune system.     

Genetic variants, immune function, and risk of pre-eclampsia among American Indians

Citation Best LG, Nadeau M, Davis K, Lamb F, Bercier S, Anderson CM. Genetic variants, immune function, and risk of pre‐eclampsia among American Indians. Am J Reprod Immunol 2012; 67: 152–159 Problem To determine the prevalence in an American Indian population of genetic variants with putative effects on immune function and determine if they are associated with pre‐eclampsia (PE). Method of study In a study of 66 cases and 130 matched controls, six single nucleotide polymorphisms (SNP) with either previously demonstrated or postulated modulating effects on the immune system were genotyped. Allele frequencies and various genetic models were evaluated by conditional logistic regression in both univariate and multiply adjusted models. Results Although most genetic variants lacked evidence of association with PE, the minor allele of the CRP related, rs1205 SNP in a dominant model with adjustment for age at delivery, nulliparity, and body mass index, exhibited an odds ratio of 0.259 (95% CI of 0.08–0.81, P = 0.020) in relation to severe PE (48 cases). The allelic prevalence of this variant was 46.1% in this population. Conclusion Of the six SNPs related to immune function in this study, a functional variant in the 3′UTR of the CRP gene was shown to be associated with severe PE in an American Indian population.     

Differential activation of placental unfolded protein response pathways implies heterogeneity in causation of early‐ and late‐onset pre‐eclampsia

Based on gestational age at diagnosis and/or delivery, pre‐eclampsia (PE) is commonly divided into early‐onset (<34 weeks) and late‐onset (≥34 weeks) forms. Recently, the distinction between ‘placental’ and ‘maternal’ causation has been proposed, with ‘placental’ cases being more frequently associated with early‐onset and intrauterine growth restriction. To test whether molecular placental pathology varies according to clinical presentation, we investigated stress‐signalling pathways, including unfolded protein response (UPR) pathways, MAPK stress pathways, heat‐shock proteins and AMPKα in placentae delivered by caesarean section for clinical indications at different gestational ages. Controls included second‐trimester, pre‐term and normal‐term placentae. BeWo cells were used to investigate how these pathways react to different severities of hypoxia–reoxygenation (H/R) and pro‐inflammatory cytokines. Activation of placental UPR and stress‐response pathways, including P‐IRE1α, ATF6, XBP‐1, GRP78 and GRP94, P‐p38/p38 and HSP70, was higher in early‐onset PE than in both late‐onset PE and normotensive controls (NTCs), with a clear inflection around 34 weeks. Placentae from ≥ 34 weeks PE and NTC were indistinguishable. Levels of UPR signalling were similar between second‐trimester and term controls, but were significantly higher in pre‐term ‘controls’ delivered vaginally for chorioamnionitis and other conditions. Severe H/R (1/20% O₂) induced equivalent activation of UPR pathways, including P‐eIF2α, ATF6, P‐IRE1α, GRP78 and GRP94, in BeWo cells. By contrast, the pro‐inflammatory cytokines TNFα and IL‐1β induced only mild activation of P‐eIF2α and GRP78. AKT, a central regulator of cell proliferation, was reduced in the < 34 weeks PE placentae and severe H/R‐treated cells, but not in other conditions. These findings provide the first molecular evidence that placental stress may contribute to the pathophysiology of early‐onset pre‐eclampsia, whereas that is unlikely to be the case in the late‐onset form of the syndrome. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Pathophysiology of hypertension in pre‐eclampsia: a lesson in integrative physiology

Despite being one of the leading causes of maternal death and a major contributor of maternal and perinatal morbidity, the mechanisms responsible for the pathogenesis of pre‐eclampsia have yet to be fully elucidated. However, it is evident that this is a complex disorder involving multiple organ systems, and by using integrative approaches, enormous progress has been made towards understanding the pathophysiology of pre‐eclampsia. Growing evidence supports the concept that the placenta plays a central role in the pathogenesis of pre‐eclampsia and that reduced uteroplacental perfusion, which develops as a result of abnormal cytotrophoblast invasion of spiral arterioles, triggers the cascade of events leading to the maternal disorder. Placental ischaemia leads to release of soluble placental factors, many of which are classified as anti‐angiogenic or pro‐inflammatory. Once these ischaemic placental factors reach the maternal circulation, they cause widespread activation and dysfunction of the maternal vascular endothelium that results in enhanced formation of endothelin‐1 and superoxide, increased vascular sensitivity to angiotensin II and decreased formation of vasodilators such as nitric oxide. This review highlights these links between placental ischaemia, maternal endothelial activation and renal dysfunction in the pathogenesis of hypertension in pre‐eclampsia.     

Relationships between maternal plasma leptin, placental leptin mRNA and protein in normal pregnancy, pre-eclampsia and intrauterine growth restriction without pre-eclampsia

Leptin, an adipocyte hormone involved in energy homeostasis, is important in reproduction and pregnancy. Questions yet to be addressed include the source of higher leptin during pregnancy and its relationship to pregnancy outcome and fetal growth. The objective of this study was to investigate the relationship between placental leptin gene expression, placental leptin protein concentration and maternal plasma leptin concentration among control pregnant women, women with pre-eclampsia and women with growth-restricted infants. We also investigated the relationship between placental leptin expression and the placental expression of enzymes involved in cellular lipid balance: fatty acid translocase (CD36), carnitine palmitoyltransferase I (CPT-1B) and lipoprotein lipase (LPL). Placental leptin expression, placental protein and maternal plasma concentration were higher in pre-eclampsia than in controls but not in women with growth-restricted infants. Placental leptin expression and placental protein were higher in the preterm pre-eclamptic subjects, whereas maternal leptin was higher in the term pre-eclamptic subjects. The placental gene expression of CD36, CPT-1B and LPL were not different among the groups. This study suggests that despite similar failed placental bed vascular remodelling in pre-eclampsia and intrauterine growth restriction (IUGR), leptin gene expression is higher only in preterm pre-eclampsia.