A role for interleukin-6 in spreading endothelial cell activation after phagocytosis of necrotic trophoblastic material: implications for the pathogenesis of pre-eclampsia

Immunomodulatory effect of efferocytosis at the maternal-fetal interface

Efferocytosis is a mechanism by which phagocytes efficiently clear apoptotic cells, averting their secondary necrosis and the subsequent release of potentially immunogenic or cytotoxic substances that can trigger strong immune and inflammatory responses. During efferocytosis, the metabolic pathways of phagocytes are transformed, which, along with the catabolism of apoptotic cargo, can affect their function and inflammatory state. Extensive apoptosis occurs during placental development, and some studies reported the immunomodulatory effects of efferocytosis at the maternal-fetal interface. The dysregulation of efferocytosis is strongly linked to pregnancy complications such as preeclampsia and recurrent spontaneous abortion. In this review, we discuss the mechanisms of efferocytosis and its relationships with metabolism and inflammation. We also highlight the roles of professional and non-professional phagocytes in efferocytosis at the maternal-fetal interface and their impact on pregnancy outcomes and explore relevant regulatory factors. These insights are expected to guide future basic research and clinical strategies for identifying efferocytosis-related molecules as potential predictors or therapeutic targets in obstetric diseases.

Cardiovascular Dysfunction in Intrauterine Growth Restriction

PURPOSE OF REVIEW

We highlight important new findings on cardiovascular dysfunction in intrauterine growth restriction.

RECENT FINDINGS

Intrauterine growth restriction (IUGR) is a multifactorial condition which negatively impacts neonatal growth during pregnancy and is associated with health problems during the lifespan. It affects 5-15% of all pregnancies in the USA and Europe with varying percentages in developing countries. Epidemiological studies have reported that IUGR is associated with the pathogenesis of hypertension, activation of the renin-angiotensin system (RAS), disruption in placental-mTORC and TGFβ signaling cascades, and endothelial dysfunction in IUGR fetuses, children, adolescents, and adults resulting in the development of cardiovascular diseases (CVD). Experimental studies are needed to investigate therapeutic measures to treat increased blood pressure (BP) and long-term CVD problems in people affected by IUGR. We outline the mechanisms mediating fetal programming of hypertension in developing CVD. We have reviewed findings from different experimental models focusing on recent studies that demonstrate CVD in IUGR.

Melatonin, a Potential Therapeutic Agent for Preeclampsia, Reduces the Extrusion of Toxic Extracellular Vesicles from Preeclamptic Placentae

Preeclampsia, characterised by maternal endothelial cell activation, is triggered by toxic factors, such as placental extracellular vesicles (EVs) from a dysfunctional placenta. The increased oxidative stress seen in the preeclamptic placenta links to endoplasmic reticulum (ER) stress. The ER regulates protein folding and trafficking. When the ER is stressed, proteins are misfolded, and misfolded proteins are toxic. Misfolded proteins can be exported from cells, via EVs which target to other cells where the misfolded proteins may also be toxic. Melatonin is a hormone and antioxidant produced by the pineal gland and placenta. Levels of melatonin are reduced in preeclampsia. In this study we investigated whether melatonin treatment can change the nature of placental EVs that are released from a preeclamptic placenta. EVs were collected from preeclamptic (n = 6) and normotensive (n = 6) placental explants cultured in the presence or absence of melatonin for 18 h. Misfolded proteins were measured using a fluorescent compound, Thioflavin-T (ThT). Endothelial cells were exposed to placental EVs overnight. Endothelial cell activation was measured by the quantification of cell-surface ICAM-1 using a cell-based ELISA. EVs from preeclamptic placentae carried significantly (p < 0.001) more misfolded proteins than normotensive controls. Incubating preeclamptic placental explants in the presence of melatonin (1 µM and 10 µM) significantly (p < 0.001) reduced the misfolded proteins carried by EVs. Culturing endothelial cells in the presence of preeclamptic EVs significantly increased the expression of ICAM-1. This increased ICAM-1 expression was significantly reduced when the endothelial cells were exposed to preeclamptic EVs cultured in the presence of melatonin. This study demonstrates that melatonin reduces the amount of misfolded proteins carried by EVs from preeclamptic placentae and reduces the ability of these EVs to activate endothelial cells. Our study provides further preclinical support for the use of melatonin as a treatment for preeclampsia.

Characterization of the extracellular matrix in the chorioallantoic membrane of water buffalo (Bubalus bubalis) in early gestation

Placenta is formed by a parenchyma rich in extracellular matrix (ECM), and this structure guarantees the proper development of the embryo and placental functioning. Recently, studies have focused on the characterization of ECM in the placenta and foetal membranes of different species. This work aimed to analyse the composition of the ECM and to quantify the types of collagens in its composition. For this, 33 chorioallantoic membranes were used at different gestational ages, which were grouped into five groups. Subsequently, haematoxylin-eosin staining, Masson trichrome and picrosirius were performed for histological analysis. Through the technique of polarized light, it was possible to quantify the total collagen present in the membranes and finally the immunohistochemical technique was performed to verify the presence of collagens and glycoproteins. It was possible to verify that the chorioallantoic membranes have, in all the gestational periods of the initial third of gestation, the same histological structures, being the most significant difference the membrane thickening that occurs gradually during the gestation. However, we notice the appearance of binucleate cells only from group II. In addition, it was verified that a gradual increase of collagen occurs until the group IV, yet from the group V begins to occur a decrease of this protein. In addition, collagen I, collagen III, fibronectin and laminin were present in all membranes. With this, we concluded that the buffalo chorioallantoic membrane presents ECM in constant remodelling at the beginning of gestation and can be used as biomaterial in works on regenerative biology.

Insights of efferocytosis in normal and pathological pregnancy

Efferocytosis, which is known as the phagocytic clearance of dying cells by professional as well as non-professional phagocytes, including a great number of intracellular/extracellular factors and signals, is interrelated with the immune system, contributing to local and systemic homeostasis, especially in tissues with high constitutive rates of apoptosis. Accumulating studies have indicated that immune dysregulation is associated with the pathogenesis of the female reproductive system, which causes preeclampsia (PE), recurrent spontaneous abortion (RSA), ruptured ectopic pregnancy, and so on. And some studies have revealed the pleiotropic and essential role of efferocytosis in these obstetrical disorders. More specifically, the occurrence and development of these diseases were in connection with some efferocytosis-related factors and signals, such as C1q, MBL, and IL-33/ST2. In this review, we systematically review the diverse impacts of efferocytosis in immune system and discuss its relevance to normal and pathological pregnancy. These findings may instruct future basic researches as well as clinical applications of efferocytosis-related factors and signals as latent predictors or therapeutic targets on the obstetrical disorders.

MicroRNAs in Preeclampsia

Preeclampsia (PE) continues to represent a worldwide problem and challenge for both clinicians and laboratory-based doctors. Despite many efforts, the knowledge acquired regarding its pathogenesis and pathophysiology does not allow us to treat it efficiently. It is not possible to arrest its progressive nature, and the available therapies are limited to symptomatic treatment. Furthermore, both the diagnosis and prognosis are frequently uncertain, whilst the ability to predict its occurrence is very limited. MicroRNAs are small non-coding RNAs discovered two decades ago, and present great interest given their ability to regulate almost every aspect of the cell function. A lot of evidence regarding the role of miRNAs in pre-eclampsia has been accumulated in the last 10 years. Differentially expressed miRNAs are characteristic of both mild and severe PE. In many cases they target signaling pathway-related genes that result in altered processes which are directly involved in PE. Immune system, angiogenesis and trophoblast proliferation and invasion, all fundamental aspects of placentation, are controlled in various degrees by miRNAs which are up- or downregulated. Finally, miRNAs represent a potential therapeutic target and a diagnostic tool.

The role of interleukins in preeclampsia: A comprehensive review

Preeclampsia is a multi-system hypertensive disorder of pregnancy, with significant rates of maternal and neonatal morbidity. It represents a major cause of preterm birth, as definitive treatment demands fetal delivery. Although its pathophysiology is complicated, placental hypoxia and endothelial dysfunction constitute established pathogenetic steps of the disease. Inflammation is considered to be a crucial mediator of preeclampsia process, as an imbalance between T_H 1, T_H 2, and T_H 17 immune responses is observed. The present review accumulates current knowledge about the contribution of interleukins in preeclampsia, summarizing the pathways through which each interleukin exerts its function in the disease. Also, the role of genetic polymorphisms is explored and the predictive efficacy of maternal serum interleukin levels is evaluated. Finally, recommendations about the safe interpretation of the outcomes, as well as guidance for future research, are provided.

Phagocytosis of Extracellular Vesicles Extruded From the Placenta by Ovarian Cancer Cells Inhibits Growth of the Cancer Cells

OBJECTIVE

Ovarian cancer is a common gynecological cancer, and parity is negatively associated with the incidence of this disease. This negative association is hypothesized to be due in part to shifting the balance of estrogen and progesterone toward more progesterone and reduced ovulation during pregnancy. However, studies suggested that parity is also associated with estrogen-independent gynecological cancers suggesting balance of hormones may not be the only protective factor. Extracellular vesicles (EVs) play an important role in cell-to-cell communication in physiological and pathological conditions. During pregnancy, large amounts of EVs are extruded from the placenta, and they seem to be involved in the remarkable adaptation of a woman's body to normal pregnancy. We hypothesized that EVs extruded from the placenta play a role in this protective effect.

METHODS

Placental EVs were collected from first-trimester placentae, and cancer cell EVs were isolated from ovarian cancer cells. The EVs were exposed to ovarian cancer cells for 48 hours. The proliferation of cancer cells and the cell cycle were measured. In addition, phagocytosis of deported placental EVs by cancer cells was also measured.

RESULTS

The proliferation of cancer cells was significantly reduced by treatment with placental EVs (P = 0.001, analysis of variance), but not EVs from monocytes (P = 0.195), compared with untreated cancer cells. Furthermore, placental EVs also prevented the proliferation of cancer cells induced by cancer cell-derived EVs (P = 0.001). This inhibition of proliferation of ovarian cancer cells was partially due to phagocytosis of placental EVs by cancer cells. Phagocytosis of placental EVs delayed progression through the cell cycle. Calreticulin, a phagocytic "eat me" signal carried by placental EVs significantly inhibited ovarian cancer growth (P = 0.001).

CONCLUSIONS

Our data demonstrated that EVs extruded from the placenta prevented ovarian cancer cell growth by a mechanism that involved delaying progression of the cell cycle after phagocytosis of the EVs.

Melatonin prevents preeclamptic sera and antiphospholipid antibodies inducing the production of reactive nitrogen species and extrusion of toxic trophoblastic debris from first trimester placentae

BACKGROUND

The exact cause of preeclampsia is unknown. However a "toxin" from the placenta triggers the condition via activation of the maternal endothelium. Extracellular vesicles (EVs) from the syncytiotrophoblast, may be an endothelial-activating toxin. Antiphospholipid antibodies (aPL) and preeclamptic sera both induce the production of endothelial cell-activating EVs by mechanisms which may produce excess free-radicals in the placenta. Melatonin is produced by the human placenta and has both direct and indirect anti-free-radical properties and may therefore counter the effects of aPL and preeclamptic sera.

METHODS

First trimester placental explants were exposed to preeclamptic sera or aPL in the presence or absence of melatonin. Nitrosylative damage was assessed in the explants by immunohistochemistry and the effect of EVs from these explants on endothelial cell activation determined by ICAM-1. Release of nitrosylated proteins from the explants was also measured.

RESULTS

Placental explants showed reduced secretion of melatonin after treatment with preeclamptic sera. Nitrosylated proteins were more abundant in placentae that had been treated with aPL or preeclamptic sera and EVs from such placentae induced endothelial cell activation. Adding melatonin to the aPL or preeclamptic sera reversed the protein nitrosylation and production of endothelial-activating EVs.

DISCUSSION

Our data are consistent with reports that the levels of circulating melatonin are reduced in preeclampsia and suggest that aPL and factors in preeclamptic sera induce free-radical-mediated damage in the placenta leading to the production of endothelial-activating EVs. Melatonin reversing production of endothelial-activating EVs indicates that melatonin may have therapeutic benefits in women with preeclampsia and/or aPL.

Key players of the necroptosis pathway RIPK1 and SIRT2 are altered in placenta from preeclampsia and fetal growth restriction

INTRODUCTION

Preeclampsia (PE) and fetal growth restriction (FGR) are among the leading causes of perinatal morbidity and mortality. Placental insufficiency is central to these conditions. The mechanisms underlying placental insufficiency are poorly understood. Apoptosis has long been considered the only form of regulated cell death, recent research has identified an alternate process of programmed cell death known as necroptosis [1]. Necroptosis is distinct from apoptosis, relying on the deacetylase sirtuin-2 [2], receptor interacting kinases RIPK1 and 3, and the pseudokinase MLKL [3]. We aimed to determine whether these key necroptosis effector molecules were present in human placenta and whether they are differentially expressed in severe preterm (PT) PE and FGR.

METHODS

PT placentas from severe early onset (<34 weeks) PE (n = 30), FGR (n = 12) and control (18) pregnancies were collected. SIRT2 and RIPK1 localization and quantitation was determined by immunohistochemistry and western blot. Immunocytochemistry was used to detect SIRT2 and RIPK1 in trophoblastic debris from first trimester, term control and PE pregnancies. Expression of SIRT2, RIPK1, RIPK3 and MLKL was examined by qPCR.

RESULTS

SIRT2 and RIPK1 were localized to the syncytiotrophoblast, villous leukocytes and vasculature in all PT placentas. A significant reduction in SIRT2 protein expression in both PE and FGR placentas was identified. RIPK1 mRNA expression was significantly increased in PE placentas. Immunofluorescence identified both SIRT2 and RIPK1 in the cytotrophoblast cytoplasm.

DISCUSSION

We have identified the presence of activators of necroptosis in human placenta. Interestingly, there is differential expression in major pregnancy complications. We conclude necroptosis may contribute to placental pathophysiology that underlies serious pregnancy complications.

Increased levels of HMGB1 in trophoblastic debris may contribute to preeclampsia

Preeclampsia is triggered by an as yet unknown toxin from the placenta. Antiphospholipid antibodies (aPL), a strong risk factor for preeclampsia, have been shown to induce the production of toxic trophoblastic debris from the placenta. High mobility group box 1 (HMGB1) is a proinflammatory danger signal, and the expression of it has been reported to be increased in preeclampsia. This study examined whether aPL or preeclamptic sera increase the expression of HMGB1 in the syncytiotrophoblast or trophoblastic debris. Trophoblastic debris from normal placental explants that had been cultured with aPL or preeclamptic sera was exposed to endothelial cells. Endothelial cell activation was quantified by cell-surface ICAM-1 expression and U937 monocyte adhesion. The expression of HMGB1 in placental explants and trophoblastic debris that had been treated with aPL or preeclamptic sera was measured by immunohistochemistry and western blotting. The expression of the receptor for advanced glycation end products (RAGE) in endothelial cells was quantified by western blotting. Compared with controls, the expression of HMGB1 in the cytoplasm of the syncytiotrophoblast and trophoblastic debris was increased by treating placental explants with aPL or preeclamptic sera. The increased levels of HMGB1 contributed to endothelial cell activation, mediated in part by the RAGE. Preeclamptic sera and aPL both induced an increase in the cytoplasmic levels of the danger signal HMGB1 in trophoblastic debris. This increased HMGB1 in trophoblastic debris may be one of the toxic factors released from the placenta in preeclampsia.

Trophoblastic debris extruded from hydatidiform molar placentae activates endothelial cells: Possible relevance to the pathogenesis of preeclampsia

INTRODUCTION

Preeclampsia is currently thought to be induced by a placental factor that triggers maternal endothelial activation. It is now well known that trophoblastic debris shed from the placenta into the maternal blood is associated with this disease. Hydatidiform mole is a pathological pregnancy characterised by hyperplastic trophoblast with little or no fetal development. Women with molar pregnancies may exhibit symptoms resembling preeclampsia. Deportation of trophoblastic debris occurs in molar pregnancies but, whether trophoblastic debris from molar pregnancies expresses pathogenic signals or activates endothelial cells is unknown.

METHODS

Trophoblastic debris were collected from either hydatidiform molar or normal first trimester placental explants and then exposed to monolayers of endothelial cell for 24 h. Endothelial cell activation was measured by quantifying cell-surface ICAM-1using ELISA. In addition, the expressions of High mobility group box 1(HMGB1) and heat shock protein 70 (HSP70) on molar placenta were examined by immunohistochemistry and western blotting. Circulating levels of sEndoglin in molar pregnancy was also measured.

RESULTS

Exposing trophoblastic debris from molar placentae increased endothelial cell surface ICAM-1 expression compared to endothelial cells exposed to trophoblastic debris from controls. Expression of HSP70 but not HMGB1 was significantly increased in hydatidiform molar placentae. The circulating levels of sEndoglin in hydatidiform molar pregnancy were not increased compared to controls.

DISCUSSION

Our results suggest that trophoblastic debris from molar pregnancies induces endothelial cell activation. HSP70 but not HMGB1 expressed on hydatidiform molar placenta may be a pathogenic signal to endothelial cells.

Reduction in the severity of early onset severe preeclampsia during gestation may be associated with changes in endothelial cell activation: A pathological case report

Early severe preeclampsia with changes consistent with the Hemolysis elevated liver enzymes low platelet count (HELLP) variant and severe fetal growth restriction rarely resolves prior to delivery. Established clinical disease is preceded by endothelial dysfunction and inflammation. Endothelial activation is reported in vitro to be raised in the presence of necrotic trophoblastic debris which is deported into the maternal circulation in preeclampsia. We report on an early severe preeclamptic patient admitted at 24 weeks gestation. Maternal serum was taken at day 2, 16, 30 of admission and 45 days postpartum. 20% maternal serum or trophoblastic debris from first trimester placental explants that had been cultured with 10% maternal serum was exposed to endothelial cells. Endothelial cell activation was quantified by the cell surface ICAM-1 expression and U937 monocyte adhesion assay. The clinical condition of this patient improved including the blood pressure, liver function, and platelet count by the 3rd day after antihypertensive treatment and remained normal until delivery at 37 weeks. ICAM-1 expression and U937 moncyte adhesion assay of endothelial cells was significantly increased following exposure of the endothelial cells to the maternal serum or trophoblastic debris from placentae treated with maternal serum drawn on day 2. However, ICAM-1 expression and the monocyte adhesion assay were significantly reduced following exposure of endothelial cells to maternal serum or trophoblastic debris from placenta treated with maternal serum drawn on day 16 or 30. Our data suggest unknown factor(s) in the maternal serum triggered endothelial cell activation when the clinical symptoms were present. The improvement in the clinical condition occurred along with the changes in endothelial cell activation.

Mid-pregnancy circulating immune biomarkers in women with preeclampsia and normotensive controls

OBJECTIVES

To determine if mid-pregnancy circulating immune biomarkers are associated with preeclampsia.

STUDY DESIGN

Nested case-control study of 410 preeclamptic women and 297 normotensive controls with primiparous singleton pregnancies enrolled in the Danish National Birth Cohort. The mean gestational age in our cohort is 16 weeks (range 9-26).

MAIN OUTCOME MEASURES

Preeclampsia was defined by blood pressure ⩾140/90 mmHg and proteinuria ⩾3 g/24 h. Serum immune biomarkers included interleukin (IL)-6, IL-6 receptor, IL-4, IL-4 receptor, IL-5, IL-12, IL-2, TNF-α, TNF-β, TNF-receptor, IL-1β, IL-1α, IL-8, IL-10, IFN-γ, IL-18, macrophage migration inhibitory factor, macrophage inflammatory protein, transforming growth factor-beta (TGF-β), and RANTES. Associations with preeclampsia, term preeclampsia and preterm preeclampsia were determined using two logistic regression models; (1) biomarkers were dichotomized by the limit of detection (LOD); (2) on the continuous scale, non-detectable values were imputed by LOD/2 and transformed (base 2). All models were adjusted for body mass index and smoking.

RESULTS

IL1β was significantly associated with a decrease in the log odds of preeclampsia (p=0.0065), term preeclampsia (p=0.0230) and preterm preeclampsia (p=0.0068). Results were similar for IL4r and preeclampsia (p=0.0383). In the dichotomized models, detectable TNF-β was significantly associated with preeclampsia (ORadj 1.6, 95% CI 1.1-2.3) and term preeclampsia (OR 1.7, 95% CI 1.1-2.5) but not preterm preeclampsia. Detectable IL6 was significantly with term preeclampsia only (OR 1.5, 95% CI 1.1-2.2).

CONCLUSION

Mid-pregnancy circulating IL1β, IL4r, IL6, and TNFβ were associated with preeclampsia. However, results were not consistent across statistical models. As the relationship is complex, future studies should explore cytokine clusters in preeclampsia risk.

Predictive Value of Free β-hCG Multiple of the Median for Women with Preeclampsia

BACKGROUND

Preeclampsia (PE) is relatively common and is unpredictable in its onset and progression.

AIMS

We investigated the clinical value of using the multiple of the median (MoM) of free β-human chorionic gonadotropin (β-hCG) concentrations in women with normal pregnancy and PE.

METHODS

This study was based on a dataset available from published studies, and the relevant studies were retrieved from multiple electronic databases. Data were extracted from case-control studies; a random-effects model was employed, and standardized mean difference and 95% confidence intervals were calculated. Twelve case-control studies (eleven English-based articles and one Chinese-based article) were analyzed in the current meta-analysis and included 702 patients with PE and 8,233 women with normal pregnancies.

RESULTS

Statistical analysis revealed a higher MoM of β-hCG serum levels in patients with PE. Ethnicity subgroup analysis showed that the MoM of serum β-hCG levels was significantly higher in women with PE in both Asian and Caucasian populations.

CONCLUSION

The MoM of β-hCG serum levels was significantly increased in women with PE compared to women with normal pregnancies. Screening for serum β-hCG MoM levels will be helpful in the early identification of pregnancies at risk of developing PE. © 2015 S. Karger AG, Basel.

The anti-inflammatory effect of calcium for preventing endothelial cell activation in preeclampsia

Preeclampsia is a disorder of pregnancy characterized by endothelial activation. It is believed to be a response to a 'toxin(s)' from the placenta including trophoblastic debris and inflammatory cytokines. Calcium is known to reduce the risk of preeclampsia but the mechanism of its protective effect remains unknown. In this study, we investigated the potential mechanism(s) of calcium supplementation for preventing endothelial activation induced by trophoblastic debris. Trophoblastic debris was harvested from preeclamptic placentae and also from first-trimester placentae, which had been treated with preeclamptic sera. Endothelial cells were then cultured with trophoblastic debris in the presence of calcium. Endothelial activation was measured by quantifying endothelial cell-surface intercellular adhesion molecule-1 (ICAM-1) and by U937 monocyte adhesion to endothelial cells. The expression of ICAM-1 and U937 adhesion to endothelial cells were significantly reduced following exposure of endothelial cells to trophoblastic debris from preeclamptic placenta or from first-trimester placentae treated with preeclamptic sera in the presence of calcium compared with treatment without calcium. The expression of ICAM-1 was also significantly reduced following exposure of endothelial cells to trophoblastic debris with the nitric oxide donor or following treatment of endothelial cells with interleukin (IL)-1β in the presence of calcium. Our study demonstrated that calcium supplementation prevented endothelial cell activation induced by trophoblastic debris from preeclamptic placentae. The nitric oxide synthase (NOS) pathway and anti-inflammatory effects are involved in the action of calcium on endothelial cell activation. These findings may suggest, at least in part, the protective mechanism of calcium supplementation on preeclampsia.

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.

Placental extracellular vesicles and feto-maternal communication

The human placenta is an anatomically unique structure that extrudes a variety of extracellular vesicles into the maternal blood (including syncytial nuclear aggregates, microvesicles, and nanovesicles). Large quantities of extracellular vesicles are produced by the placenta in both healthy and diseased pregnancies. Since their first description more than 120 years ago, placental extracellular vesicles are only now being recognized as important carriers for proteins, lipids, and nucleic acids, which may play a crucial role in feto-maternal communication. Here, we summarize the current literature on the cargos of placental extracellular vesicles and the known effects of such vesicles on maternal cells/systems, especially those of the maternal immune and vascular systems.

Severe preeclampsia: association of genes polymorphisms and maternal cytokines production in Brazilian population

INTRODUCTION

Preeclampsia (PE) is a multi-system disorder of pregnancy characterized by hypertension and proteinuria. Healthy pregnancy is associated with a controlled inflammatory process, which is exacerbated in PE in response to excessive placental stimuli. Gene expression levels can affect inflammation and immune regulation. It is known that differences in cytokine allele frequencies amongst populations may contribute to difference in the incidence of several diseases.

OBJECTIVE

The aim of this study was to investigate the frequency of TNF-α, IL-6, IFN-γ and IL-10 genes polymorphisms and their relationship with the cytokines plasma levels in PE.

METHODS

A total of 281 women were included in this study; 116 with severe PE, 107 normotensive pregnant and 58 non-pregnant women. Cytokine genotyping was carried out by the polymerase chain reaction. The analyzed polymorphisms were: TNF-α (-308 G→A), IL-10 (-1082 G→A), IL-6 (-174 G→C), and IFN-γ (+874 A→T). Cytokine plasma levels were measured by Cytometric Bead Array method.

RESULTS

A higher frequency of the IFN-γ (+874) T/T genotype in severe PE comparing to normotensive pregnant women was found (P<0.001). TNF-α, IL-6 and IFN-γ plasma levels were higher in PE women compared to non-pregnant women (P<0.001; P<0.001; P=0.004). IL-6 and IFN-γ levels were also higher in PE women compared to normotensive pregnant (P<0.001; P=0.010). IL-10 levels were higher in normotensive pregnant women compared to PE (P<0.001). IFN-γ and IL-6 genes polymorphisms influenced the genic expression in PE and normotensive pregnant women, respectively.

CONCLUSIONS

These results suggest that IFN-γ seems to play a role in PE occurrence.

Trophoblast debris extruded from preeclamptic placentae activates endothelial cells: a mechanism by which the placenta communicates with the maternal endothelium

INTRODUCTION

Preeclampsia is characterized by maternal endothelial dysfunction. While the mechanisms leading to preeclampsia are unclear, a factor(s) from the placenta is responsible for triggering the disease. One placental factor implicated in triggering preeclampsia is trophoblast debris which may transmit pathogenic signals from the placenta to endothelial cells. In this study, we investigated whether trophoblast debris from preeclamptic placentae triggered endothelial cell activation.

METHODS

Trophoblast debris from preeclamptic or normotensive placentae, or trophoblast debris from normal placental explants that had been cultured with preeclamptic (n = 14) or normotensive sera (n = 14) was exposed to endothelial cells. Activation of the endothelial cells was quantified by cell surface ICAM-1 and U937 adhesion to endothelial cells. The levels of IL-1β, pro-caspase-1 and active caspase-1 in the trophoblast debris were measured.

RESULTS

Compared to controls, the levels of ICAM-1 and U937 adhesion to endothelial cells were significantly increased following exposure of the endothelial cells to trophoblast debris from preeclamptic placentae or placentae treated with preeclamptic sera. The levels IL-1β, pro-caspase-1 and active caspase-1 were significantly increased in both trophoblast debris from preeclamptic placentae and placentae treated with preeclamptic sera.

DISCUSSION

These results provide the first direct evidence that trophoblast debris produced from preeclamptic placentae or placentae treated with preeclamptic sera can activate the endothelium.

CONCLUSIONS

Trophoblast debris from preeclamptic but not normotensive placentae can induce endothelial cell activation. This may be one mechanism by which the preeclamptic placenta communicates with the maternal endothelium to induce activation of the endothelium.

Calcium supplementation prevents endothelial cell activation: possible relevance to preeclampsia

OBJECTIVES

Preeclampsia is a leading cause of maternal and fetal mortality and morbidity. A hallmark of preeclampsia is endothelial cell dysfunction/activation in response to 'toxins' from the placenta. Necrotic trophoblastic debris (NTD) is one possible placental toxin and other activators of endothelial cells include inflammatory cytokines. Calcium supplementation appears to protect 'at-risk' women from developing preeclampsia but how is unclear.

METHODS

Placental explants were cultured with interleukin-6 (IL-6) in varied concentrations of calcium. The resultant trophoblastic debris was exposed to endothelial cells. Endothelial cells were exposed to activators including NTD, IL-6, and preeclamptic sera in the presence of varied concentrations of calcium and activation monitored by quantifying cell surface markers by ELISA.

RESULTS

Raising the levels of calcium did not prevent the IL-6-induced shedding of NTD from placental explants but did prevent the activation of endothelial cells in response to IL-6, preeclamptic sera, or NTD. Reducing the level of calcium directly induced the activation of endothelial cells. Inhibiting nitric oxide synthetase ablated the ability of high calcium levels to protect endothelial cell activation. The activity of endothelial cell nitric oxide synthetase was blocked with L-N-nitroarginine methyl ester.

CONCLUSION

Our results demonstrate calcium levels do not affect the shedding of trophoblastic debris but are important to endothelial cell activation and supplemental calcium may reverse the activation of the endothelium in preeclamptic women. These results may in part explain the benefits of calcium supplementation in the reduction of risk for developing preeclampsia and provide in-vitro mechanistic support for the use of calcium supplementation in at-risk women.

Polymeric stent materials dysregulate macrophage and endothelial cell functions: implications for coronary artery stent

BACKGROUND

Biodegradable polymers have been applied as bulk or coating materials for coronary artery stents. The degradation of polymers, however, could induce endothelial dysfunction and aggravate neointimal formation. Here we use polymeric microparticles to simulate and demonstrate the effects of degraded stent materials on phagocytic activity, cell death and dysfunction of macrophages and endothelial cells.

METHODS

Microparticles made of low molecular weight polyesters were incubated with human macrophages and coronary artery endothelial cells (ECs). Microparticle-induced phagocytosis, cytotoxicity, apoptosis, cytokine release and surface marker expression were determined by immunostaining or ELISA. Elastase expression was analyzed by ELISA and the elastase-mediated polymer degradation was assessed by mass spectrometry.

RESULTS

We demonstrated that poly(D,L-lactic acid) (PLLA) and polycaprolactone (PCL) microparticles induced cytotoxicity in macrophages and ECs, partially through cell apoptosis. The particle treatment alleviated EC phagocytosis, as opposed to macrophages, but enhanced the expression of vascular cell adhesion molecule (VCAM)-1 along with decreased nitric oxide production, indicating that ECs were activated and lost their capacity to maintain homeostasis. The activation of both cell types induced the release of elastase or elastase-like protease, which further accelerated polymer degradation.

CONCLUSIONS

This study revealed that low molecule weight PLLA and PCL microparticles increased cytotoxicity and dysregulated endothelial cell function, which in turn enhanced elastase release and polymer degradation. These indicate that polymer or polymer-coated stents impose a risk of endothelial dysfunction after deployment which can potentially lead to delayed endothelialization, neointimal hyperplasia and late thrombosis.

Oncostatin M stimulates cell migration and proliferation by down-regulating E-cadherin in HTR8/SVneo cell line through STAT3 activation

BACKGROUND

During the first trimester of pregnancy, trophoblastic E-cadherin expression is down-regulated, thereby allowing extravillous trophoblasts (EVTs) to acquire the potential for migration and invasiveness. The aim of the present study was to investigate the role of OSM on the migration and proliferation of EVT cell line HTR8/SVneo with regard to its effects on the expression of E-cadherin and STAT3 activation.

METHODS

We investigated the effects of OSM on RNA and protein expression of E-cadherin by real time RT-PCR analyses, western blotting, and indirect immunofluorescence staining in HTR8/SVneo cells, as well as the effects on cell migration and proliferation. The selective signal transducer and activator of transcription (STAT)3 inhibitor, stattic, and STAT3 siRNA were used to investigate STAT3 activation by OSM.

RESULTS

OSM significantly reduced RNA and protein expression of E-cadherin. Indirect immunofluorescence staining of HTR8/SVneo cells also revealed the down-regulation of E-cadherin, compared with the controls. OSM-stimulated cell migration was attenuated by anti-gp130 antibodies. OSM-induced STAT3 phosphorylation, and the down-regulation of E-cadherin by OSM treatment was restored by stattic and STAT3 siRNA. In addition, OSM-stimulated migration and proliferation were significantly suppressed by STAT3 inhibition.

CONCLUSIONS

This study suggests that OSM stimulates the migration and proliferation of EVTs during the first trimester of pregnancy through the down-regulation of E-cadherin. In addition, this study suggests that the effects of OSM on migration and proliferation are related to STAT3 activation, which is important in trophoblast invasiveness.

Placental expression of VEGF is increased in pregnancies with hydatidiform mole: possible association with developing very early onset preeclampsia

BACKGROUND

Hydatidiform mole is an abnormal pregnancy with over-proliferation of the placenta, which causes the dysfunction of placenta. Although more than 80% of hydatidiform moles are benign with good outcome, hydatidiform moles are associated with developing very early onset preeclampsia. However the association between hydatidiform mole and very early onset preeclampsia is unclear. Preeclampsia is associated with altered levels of angiogenic factors, like vascular endothelial growth factor (VEGF) and soluble endoglin.

AIM

The aim of this study is to investigate the levels of VEGF and endoglin in hydatidiform molar placenta.

STUDY DESIGN

21 placentas from complete hydatidiform mole, 9 placentas from partial hydatidiform mole and 18 placentas from gestation matched placenta were collected in this study.

SUBJECTS

The subjects of this study are human placentas.

OUTCOME MEASURES

The protein levels and mRNA levels of VEGF and endoglin were measured using immunohistochemistry, western blotting and real time PCR.

RESULTS

The protein levels of VEGF measured by immunohistochemistry and western blotting were significant increased, as well as mRNA levels of VEGF quantified by real time PCR in hydatidiform molar placenta in comparison to normal controls. There was no difference in the protein levels of VEGF between complete and partial hydatidiform moles. In contrast, the levels of protein and mRNA in endoglin were no difference between hydatidiform molar placenta and normal controls.

CONCLUSION

In this study our data show that hydatidiform moles produce more VEGF than normal early pregnant placenta. The increased levels of angiogenic factors VEGF in hydatidiform moles may link to the mechanism of developing very early onset preeclampsia.

Tumor necrosis factor-alpha, interleukin-6, and interleukin-10 levels are altered in preeclampsia: a systematic review and meta-analysis

PROBLEM

Published reports testing the association between cytokine levels and preeclampsia are conflicting. This comprehensive systematic review and meta-analysis aimed at testing the association between preeclampsia and maternal circulating tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-10.

METHOD OF STUDY

A systematic literature search of studies reporting maternal circulating TNF-α, IL-6, and IL-10 in women with preeclampsia and normotensive pregnant women was conducted yielding 41, 28, and 12 eligible reports, respectively.

RESULTS

Both mild preeclampsia and severe preeclampsia were associated with elevated TNF-α [mean difference (MD) = 7.34 pg/mL, 95% CI 5.02-9.66 and MD = 7.91 pg/mL, 95% CI 4.72-11.10, respectively] and IL-6 (MD = 61.01 pg/mL, 95% CI 14.24-107.77 and MD = 28.54 pg/mL, 95% CI 15.90-41.17, respectively) in the third trimester. Preeclampsia was also associated with elevated levels of IL-10 (MD = 5.54, 95% CI 0.69-10.38). The systematic review of studies reporting median data was in consensus with the parametric data.

CONCLUSION

This systematic review and meta-analysis with accompanying summary of non-parametric data shows elevated maternal circulating TNF-α, IL-6, and IL-10 levels in preeclampsia.

Genetic dissection of the pre-eclampsia susceptibility locus on chromosome 2q22 reveals shared novel risk factors for cardiovascular disease

Pre-eclampsia is an idiopathic pregnancy disorder promoting morbidity and mortality to both mother and child. Delivery of the fetus is the only means to resolve severe symptoms. Women with pre-eclamptic pregnancies demonstrate increased risk for later life cardiovascular disease (CVD) and good evidence suggests these two syndromes share several risk factors and pathophysiological mechanisms. To elucidate the genetic architecture of pre-eclampsia we have dissected our chromosome 2q22 susceptibility locus in an extended Australian and New Zealand familial cohort. Positional candidate genes were prioritized for exon-centric sequencing using bioinformatics, SNPing, transcriptional profiling and QTL-walking. In total, we interrogated 1598 variants from 52 genes. Four independent SNP associations satisfied our gene-centric multiple testing correction criteria: a missense LCT SNP (rs2322659, P = 0.0027), a synonymous LRP1B SNP (rs35821928, P = 0.0001), an UTR-3 RND3 SNP (rs115015150, P = 0.0024) and a missense GCA SNP (rs17783344, P = 0.0020). We replicated the LCT SNP association (P = 0.02) and observed a borderline association for the GCA SNP (P = 0.07) in an independent Australian case-control population. The LRP1B and RND3 SNP associations were not replicated in this same Australian singleton cohort. Moreover, these four SNP associations could not be replicated in two additional case-control populations from Norway and Finland. These four SNPs, however, exhibit pleiotropic effects with several quantitative CVD-related traits. Our results underscore the genetic complexity of pre-eclampsia and present novel empirical evidence of possible shared genetic mechanisms underlying both pre-eclampsia and other CVD-related risk factors.

Expression of inflammatory cytokines in placentas from pregnancies complicated with preeclampsia and HELLP syndrome

OBJECTIVE

To investigate the expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) in villous trophoblast, syncytial knots and decidua placentas from pregnancies complicated with preeclampsia (PE), Hemolysis, Elevated Liver enzymes and Low Platelet count (HELLP) syndrome and gestational age-matched controls.

METHODS

Study group included 35 placentas from pregnancies complicated with PE and 35 placentas from pregnancies with HELLP syndrome. Control group included 35 placentas from idiopathic preterm labor. Placentas were matched according to the gestational age. Expression of TNF-α, IL-6 and IL-10 was determined by immunohistochemistry and semi-quantitative HSCORE method in villous trophoblast, syncytial knots and decidua. Non-parametric statistics were used for analyses.

RESULTS

There was no difference in the expression of TNF-α, IL-6 and IL-10 in all the studied placental segments between PE, HELLP and gestational age-matched control group. TNF-α (F = 32, 41, p < 0.001), IL-6 (F = 58, 53, p < 0.001) and IL-10 (F = 17, 62, p < 0.001) expression was significantly different in different placental cell types, the highest expression of cytokines was in decidua.

CONCLUSION

There was no difference in cytokine expression in villous trophoblast, syncytial knots and decidua among the studied placental groups. The expression of cytokines was highest in decidua in all the studied placental groups.

Calcium channel blockers prevent endothelial cell activation in response to necrotic trophoblast debris: possible relevance to pre-eclampsia

AIMS

Pre-eclampsia is characterized by endothelial activation, which is triggered by placental factor(s). One such factor may be trophoblastic debris that is shed into the maternal blood to become trapped against the maternal pulmonary endothelium. Phagocytosis of necrotic trophoblastic debris (NTD) induces endothelial cell activation with increased secretion of interleukin-6 (IL-6) and transforming growth factor β1 (TGFβ1), which may induce systemic endothelial cell activation. In addition to its effects on vascular smooth muscle, evidence suggests that nifedipine may also affect the endothelium, contributing to the therapeutic benefits of the drug. We investigated whether nifedipine could reverse the endothelial cell activation induced by NTD.

METHODS AND RESULTS

Trophoblastic debris was collected from placental explants and exposed to endothelial cells with or without nifedipine, verapamil, or a nitric oxide (NO) donor for 24 h. Endothelial cell activation was measured by cell-surface intracellular adhesion molecule-1 and E-selectin, as well as monocyte adhesion. The activation of endothelial cells exposed to NTD or sera from pre-eclamptic women was significantly reduced by nifedipine or verapamil. In addition, the increases in the levels of IL-6 or TGFβ1 in conditioned media from endothelial cells following phagocytosis of NTD were significantly reduced by nifedipine. These actions of nifedipine were reversed by the NO synthetase inhibitor l-NAME and mimicked by a NO donor.

CONCLUSION

Our results suggest that calcium channel blockers may have a direct effect upon endothelial cells, reducing the endothelial cell activation that is a key pathogenic feature of pre-eclampsia. This action may be mediated, in part, by NO.

Molecular genetics of preeclampsia and HELLP syndrome - a review

Preeclampsia is characterised by new onset hypertension and proteinuria and is a major obstetrical problem for both mother and foetus. Haemolysis elevated liver enzymes and low platelets (HELLP) syndrome is an obstetrical emergency and most cases occur in the presence of preeclampsia. Preeclampsia and HELLP are complicated syndromes with a wide variety in severity of clinical symptoms and gestational age at onset. The pathophysiology depends not only on periconceptional conditions and the foetal and placental genotype, but also on the capability of the maternal system to deal with pregnancy. Genetically, preeclampsia is a complex disorder and despite numerous efforts no clear mode of inheritance has been established. A minor fraction of HELLP cases is caused by foetal homozygous LCHAD deficiency, but for most cases the genetic background has not been elucidated yet. At least 178 genes have been described in relation to preeclampsia or HELLP syndrome. Confined placental mosaicism (CPM) is documented to cause early onset preeclampsia in some cases; the overall contribution of CPM to the occurrence of preeclampsia has not been adequately investigated yet. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

Toll-like receptor 9 activation: a novel mechanism linking placenta-derived mitochondrial DNA and vascular dysfunction in pre-eclampsia

Emerging evidence suggests that in addition to being the 'power houses' of our cells, mitochondria facilitate effector responses of the immune system. Cell death and injury result in the release of mtDNA (mitochondrial DNA) that acts via TLR9 (Toll-like receptor 9), a pattern recognition receptor of the immune system which detects bacterial and viral DNA but not vertebrate DNA. The ability of mtDNA to activate TLR9 in a similar fashion to bacterial DNA stems from evolutionarily conserved similarities between bacteria and mitochondria. mtDNA may be the trigger of systemic inflammation in pathologies associated with abnormal cell death. PE (pre-eclampsia) is a hypertensive disorder of pregnancy with devastating maternal and fetal consequences. The aetiology of PE is unknown and removal of the placenta is the only effective cure. Placentas from women with PE show exaggerated necrosis of trophoblast cells, and circulating levels of mtDNA are higher in pregnancies with PE. Accordingly, we propose the hypothesis that exaggerated necrosis of trophoblast cells results in the release of mtDNA, which stimulates TLR9 to mount an immune response and to produce systemic maternal inflammation and vascular dysfunction that lead to hypertension and IUGR (intra-uterine growth restriction). The proposed hypothesis implicates mtDNA in the development of PE via activation of the immune system and may have important preventative and therapeutic implications, because circulating mtDNA may be potential markers of early detection of PE, and anti-TLR9 treatments may be promising in the management of the disease.

Interleukin-6 in pregnancy and gestational disorders

IL6 is a multifunctional cytokine with pivotal roles in the inflammatory response and in directing T cell differentiation in adaptive immunity. IL6 is widely expressed in the female reproductive tract and gestational tissues, and exerts regulatory functions in embryo implantation and placental development, as well as the immune adaptations required to tolerate pregnancy. Here, we summarise the current understanding of how membrane-bound and soluble receptors mediate IL6 signalling to regulate leukocytes and non-haemopoietic cells. We review the published literature regarding the expression and actions of IL6 in the uterus, decidua and placenta, and studies implicating this cytokine in pregnancy disorders. Elevated IL6 is frequently evident in the altered cytokine profiles characteristic of unexplained infertility, recurrent miscarriage, preeclampsia and preterm delivery. Notably, there is compelling evidence indicating altered systemic IL6 trans-signalling in women prone to recurrent miscarriage, with excessive IL6 bioavailability potentially inhibiting generation of CD4+ T regulatory cells required for pregnancy tolerance. Insufficient local IL6 may also contribute to fetal loss, since IL6 expression is reduced in the endometrium of women with recurrent miscarriage, and in the fetal-placental tissue of CBA×DBA/2 mice. Consistent with the role of IL6 in key reproductive events, Il6 null mutant mice exhibit elevated fetal resorption and delayed parturition. Investigation of the association between IL6 signalling components and T cell responses in pregnant women, as well as detailed analysis of the maternal immune response in IL6-deficient mice, is now required to define the mechanisms by which this cytokine exerts influence on reproductive success.

Trophoblast deportation: just a waste disposal system or antigen sharing?

Trophoblast deportation, the removal of trophoblastic debris from the placenta via the maternal blood, was first described over 100 years ago. Deported trophoblastic debris ranges in size from nano-meter scale subcellular particles to large multinucleated syncytial knots. Whether trophoblast deportation has any biological significance remains unclear. However, the (semi) allogeneic fetus must induce maternal tolerance to paternally inherited placental antigens. We propose that the clearance of deported trophoblasts may be a mechanism by which the maternal immune system is maintained in a state of tolerance towards paternal antigens. Using an in vitro model, we have shown that when syncytial knots are shed by an apoptosis-like programmed cell death process, then phagocytosed by macrophages, the macrophages produce a tolerogenic response. However, necrotic syncytial knots, when phagocytosed, appear to be immunostimulatory. We have also shown that endothelial cells are likely to be involved in the clearance of syncytial knots from the pulmonary vessels. Phagocytosis of apoptotic syncytial knots by endothelial cells is silent while phagocytosis of necrotic syncytial knots leads to endothelial cell activation characterised by increased endothelial cell-surface adhesion molecule expression and secretion of IL-6 and TGFβ1. All of these molecules may interact with the maternal immune system to exacerbate any adverse maternal response. We propose that in normal pregnancy clearance of apoptotic syncytial knots is important to maintain maternal immune tolerance to the fetus and that in abnormal pregnancies, especially preeclampsia, clearance of necrotic syncytial knots may contribute to the pathogenesis of that condition.

Spreading endothelial cell dysfunction in response to necrotic trophoblasts. Soluble factors released from endothelial cells that have phagocytosed necrotic shed trophoblasts reduce the proliferation of additional endothelial cells

The pathogenesis of preeclampsia is not clear but the disease is characterised by systemic endothelial cell dysfunction that is considered to be triggered by a placental factor. Necrotic trophoblastic debris that is deported in the maternal blood is one possible placental trigger for preeclampsia. Syncytial knots were first associated with preeclampsia over 100 years ago. However, syncytial knots are very large and most are trapped in the pulmonary capillaries making it difficult to envisage how they could lead to widespread systemic endothelial cell dysfunction. This study was undertaken to examine whether conditioned medium from endothelial cells that have phagocytosed necrotic trophoblastic debris could adversely affect the proliferation or survival of fresh endothelial cells. Trophoblastic cellular debris, harvested from placental explants was added to endothelial cell monolayers directly or after induction of necrosis by freeze-thawing. Conditioned medium from the endothelial cell cultures was exposed to fresh endothelial cells and their proliferation measured by Alamar Blue, and CyQUANTNF cell proliferation assays. Endothelial cell death was examined by a fluorogenic caspase-3 activity assay and LDH release. Conditioned medium from endothelial cells that had phagocytosed necrotic but not apoptotic trophoblastic debris significantly inhibited the proliferation of fresh endothelial cells but did not induce their death. The conditioned medium also reduced cell-surface endoglin expression by fresh endothelial cells. These results confirm that phagocytosis of necrotic trophoblastic debris by endothelial cells results in the secretion of soluble factors that might explain how necrotic trophoblastic debris trapped in the pulmonary capillaries could induce systemic endothelial cell dysfunction.

Pre-eclampsia: fitting together the placental, immune and cardiovascular pieces

The success of pregnancy is a result of countless ongoing interactions between the placenta and the maternal immune and cardiovascular systems. Pre-eclampsia is a serious pregnancy complication that arises from multiple potential aberrations in these systems. The pathophysiology of pre-eclampsia is established in the first trimester of pregnancy, when a range of deficiencies in placentation affect the key process of spiral artery remodelling. As pregnancy progresses to the third trimester, inadequate spiral artery remodelling along with multiple haemodynamic, placental and maternal factors converge to activate the maternal immune and cardiovascular systems, events which may in part result from increased shedding of placental debris. As we understand more about the pathophysiology of pre-eclampsia, it is becoming clear that the development of early- and late-onset pre-eclampsia, as well as intrauterine growth restriction (IUGR), does not necessarily arise from the same underlying pathology.

Different responsiveness of endothelial cells to vascular endothelial growth factor and basic fibroblast growth factor added to culture media under gravity and simulated microgravity

When incubated under simulated microgravity (s-microg), endothelial cells (EC) form tubular structures that resemble vascular intimas. This delayed formation of 3D EC structures begins between the 5th and 7th day of culturing EC under conditions of s-microg, when double-row cell assemblies become visible. With the aim of learning about this initial phase of tubular structure formation, we found that NFkappaBp65 protein content was similar in all cell populations, but gene and protein expression of phosphokinase A catalytic subunit, phosphokinase Calpha, and extracellular signal-regulated kinases 1 and 2 was altered in cells cultured under s-microg. Apoptosis remained below 30% in all EC cultures. In contrast to controls, the 7-day-old s-microg cultures contained 3D aggregates with proliferating cells, enhanced numbers of necrotic cells, and osteopontin-negative EC as well as supernatants with reduced quantities of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), soluble TNFRSF5, TNFSF5, intercellular adhesion molecule-1, tumor necrosis factor receptor 2, IL-18, complement C3, and von Willebrand factor. VEGF and/or bFGF (10 ng/mL) application influenced the accumulation of proteins in supernatants more profoundly under 1 g than under s-microg. These findings provide evidence that phosphokinase Calpha plays a key role in tube formation. Improving the interaction of VEGF and/or bFGF with EC under s-microg could enhance the engineering of vascular intimas.

The role of autocrine TGFbeta1 in endothelial cell activation induced by phagocytosis of necrotic trophoblasts: a possible role in the pathogenesis of pre-eclampsia

Pre-eclampsia is a disorder of pregnancy characterized by hypertension and endothelial cell dysfunction. The causes of pre-eclampsia are unclear but it is proposed that a factor released from the placenta triggers the maternal symptoms. One possible triggering factor is dead trophoblasts that are shed from the placenta, then deported to become trapped in the maternal pulmonary capillaries. It is hypothesized that trophoblasts die by apoptosis in normal pregnancy, but by necrosis in pre-eclampsia. Deported trophoblasts may be phagocytosed by the pulmonary endothelial cells and we have previously shown that phagocytosis of necrotic trophoblasts leads to the activation of endothelial cells, accompanied by the release of interleukin-6 from these cells. However, the mechanistic pathway linking phagocytosis of necrotic trophoblasts and endothelial cell activation is unknown. Here we show that, after phagocytosis of necrotic, but not apoptotic, trophoblasts, endothelial cells secrete TGFbeta1. Using recombinant endoglin to inhibit the function of TGFbeta1 we have shown that the TGFbeta1 does not directly activate endothelial cells but rather it induces endothelial IL-6 secretion. The IL-6 then induces endothelial cell activation. Inhibiting either TGFbeta1 or IL-6 prevented endothelial cell activation in response to phagocytosing necrotic trophoblasts, but inhibiting IL-6 did not prevent secretion of TGFbeta1, confirming the order of signalling. IL-6 also reduced endothelial cell-surface endoglin but increased the amount of soluble endoglin released from placental explants. These interactions between the IL-6 and TGFbeta1 pathways in both the endothelium and placenta may help to regulate the maternal response to deported trophoblasts in pregnancy.

Anti-phospholipid antibodies increase non-apoptotic trophoblast shedding: a contribution to the pathogenesis of pre-eclampsia in affected women?

Pre-eclampsia is associated with trophoblast shedding-deportation and endothelial cell dysfunction. Anti-phospholipid autoantibodies increase a women's risk factor of developing pre-eclampsia. In this study we examined the hypothesis that anti-phospholipid antibodies alter the number and nature of trophoblasts shed from the placenta, and that phagocytosis of these altered trophoblasts results in endothelial cell activation. To investigate this we used a placental explant model in which explants were treated with anti-phospholipid antibodies. This treatment resulted in a doubling of the amount of trophoblast shed from the explants. Furthermore, the trophoblasts shed from anti-phospholipid antibody-treated explants were more readily phagocytosed by endothelial cells and subsequently caused the activation of the endothelial cells, as indicated by increased expression of endothelial cell surface ICAM-1 determined by cell-based ELISA, and monocyte adhesion as determined by flow cytometry. Confocal microscopy analysis of trophoblasts shed from anti-phospholipid antibody-treated or control explants demonstrated that anti-phospholipid antibodies, but not control antibodies, were internalised within trophoblasts shed from the explants, and this was accompanied by a reduction in the activity of caspases 3 and 7 in the shed trophoblasts as indicated by FLICA. These results suggest that anti-phospholipid antibodies are selectively transported into trophoblasts where they affect the regulation of the cell cycle leading to excess and aberrant death (necrotic or aponecrotic) and shedding of trophoblasts. If reflected in vivo this might explain, at least in part, how anti-phospholipid antibodies contribute to the pathogenesis of pre-eclampsia.