Role of placenta growth factor (PIGF) in human extravillous trophoblast proliferation, migration and invasiveness

Immunological mechanisms in preeclampsia: A narrative review

Maternal immunologic mechanisms for tolerance are essential for a successful pregnancy because they prevent maladaptive immune responses to the placenta and semi-allogeneic fetus and promote fetal growth. Preeclampsia is a major global cause of fetal mortality and morbidity. It is characterized by new-onset hypertension and proteinuria that occurs at twenty weeks of pregnancy or later. Preeclampsia is defined by a rise in cytokines that are pro-inflammatory and antiangiogenic components in the fetoplacental unit and the vascular endothelium of pregnant women, as well as an excessive and increasing stimulation of the immune system. Crucially, inflammation can result in low birth weight and inadequate placental perfusion in neonates. Preeclampsia, which is ultimately connected to inflammatory responses, can be impacted by several immunological mechanisms. Our goal in this work was to compile the most recent research on the pathoimmunology of preeclampsia, including studies on angiogenic variables and, in particular, immunological components.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

Alleviation of preeclampsia-like symptoms through PlGF and eNOS regulation by hypoxia- and NF-κB-responsive miR-214-3p deletion

Preeclampsia is caused by placental hypoxia and systemic inflammation and is associated with reduced placental growth factor (PlGF) and endothelial nitric oxide synthase (eNOS) levels. The molecular signaling axes involved in this process may play a role in the pathogenesis of preeclampsia. Here, we found that hypoxic exposure increased hypoxia-inducible factor-1α (HIF-1α)/Twist1-mediated miR-214-3p biogenesis in trophoblasts, suppressing PlGF production and trophoblast invasion. TNF-α stimulation increased NF-κB-dependent miR-214-3p expression in endothelial cells, impairing eNOS expression and causing endothelial dysfunction. Synthetic miR-214-3p administration to pregnant mice decreased PlGF and eNOS expression, resulting in preeclampsia-like symptoms, including hypertension, proteinuria, and fetal growth restriction. Conversely, miR-214-3p deletion maintained the PlGF and eNOS levels in hypoxic pregnant mice, alleviating preeclampsia-like symptoms and signs. These findings provide new insights into the role of HIF-1/Twist1- and NF-κB-responsive miR-214-3p-dependent PlGF and eNOS downregulation in the pathogenesis of preeclampsia and establish miR-214-3p as a therapeutic or preventive target for preeclampsia and its complications.

The correlation between serum levels and placental tissue expression of PLGF and sFLT-1 and the FIGO grading of the placenta accreta spectrum disorders

OBJECTIVE

This study aims to further explore the role of angiogenic vs anti-angiogenic factors in placenta accreta spectrum (PAS).

METHODS

This cohort study included all patients with placenta previa and placenta accreta spectrum (PAS) disorders undergoing surgery at Dr. Soetomo Hospital (Academic Hospital of Universitas Airlangga, Surabaya, Indonesia) from May to September 2021. Venous blood samples for PLGF and sFlt-1 were drawn immediately prior to surgery. Placental tissue samples were taken during surgery. The FIGO grading was diagnosed intraoperatively by an experienced surgeon and confirmed by the pathologist and followed by immunohistochemistry (IHC) staining. The sFlt-1 and PLGF serum were performed by an independent laboratory technician.

RESULTS

Sixty women were included in this study (20 women with placenta previa; 10 women with FIGO PAS grade 1; 8 women with FIGO PAS grade 2; 22 women with FIGO PAS grade 3). The median with 95% Confidence interval of PLGF serum values in placenta previa, FIGO grade I, grade II, and grade III were 233.68 (0.00-2434.00), 124.39 (10.42-663.68), 236.89 (18.83-418.99) and 237.31 (2.26-3101.00) (p = .736); the median values with 95% CI of serum sFlt-1 levels in placenta previa, FIGO grade I, grade II, and grade III were 2816.50 (418.00-12925.00), 2506.00 (227.50-16104.00), 2494.50 (888.52-20812.00), and 1601.00 (662.16-9574.00) (p = .037). Placental PLGF expression in placenta previa, FIGO grade 1, grade II, and grade III showed median values (with 95% CI) of 4.00 (1.00-9.00), 4.00 (2.00-9.00), 4.00 (4.00-9.00), and 6.00 (2.00-9.00) (p = .001); sFlt-1 expression median values (with 95% CI) were 6.00 (2.00-9.00), 6.00 (2.00-9.00), 4.00 (1.00-9.00), and 4.00 (1.00-9.00) (p = .004). Serum PLGF and sFlt-1 levels did not correlate with placental tissue expression (p = .228; p = .586).

CONCLUSION

There are differences in PAS's angiogenic processes ​according to the severity of trophoblast cell invasion. But there is no overall correlation between serum levels and PLGF and sFlt-1 expression in the placenta, suggesting the imbalance between angiogenic and anti-angiogenic are local mechanisms in the placental and the uterine wall.

Human Chorionic Villous Differentiation and Placental Development

In humans, the placenta provides the only fetomaternal connection and is essential for establishing a pregnancy as well as fetal well-being. Additionally, it allows maternal physiological adaptation and embryonic immunological acceptance, support, and nutrition. The placenta is derived from extra-embryonic tissues that develop rapidly and dynamically in the first weeks of pregnancy. It is primarily composed of trophoblasts that differentiate into villi, stromal cells, macrophages, and fetal endothelial cells (FEC). Placental differentiation may be closely related to perinatal diseases, including fetal growth retardation (FGR) and hypertensive disorders of pregnancy (HDP), and miscarriage. There are limited findings regarding human chorionic villous differentiation and placental development because conducting in vivo studies is extremely difficult. Placental tissue varies widely among species. Thus, experimental animal findings are difficult to apply to humans. Early villous differentiation is difficult to study due to the small tissue size; however, a detailed analysis can potentially elucidate perinatal disease causes or help develop novel therapies. Artificial induction of early villous differentiation using human embryonic stem (ES) cells/induced pluripotent stem (iPS) cells was attempted, producing normally differentiated villi that can be used for interventional/invasive research. Here, we summarized and correlated early villous differentiation findings and discussed clinical diseases.

AT2R activation increases in vitro angiogenesis in pregnant human uterine artery endothelial cells

Angiogenesis is vital during pregnancy for remodeling and enhancing vasodilation of maternal uterine arteries, and increasing uterine blood flow. Abnormal angiogenesis is associated with decreased uteroplacental blood flow and development of pregnancy disorders such as gestational hypertension, preeclampsia, fetal growth restriction, preterm delivery, stillbirth, and miscarriage. The mechanisms that contribute to normal angiogenesis remain obscure. Our previous studies demonstrated that expression of the angiotensin type 2 receptor (AT2R) is increased while the angiotensin type 1 receptor (AT1R) is unchanged in the endothelium of uterine arteries, and that AT2R-mediated pregnancy adaptation facilitates enhanced vasodilation and uterine arterial blood flow. However, the role of AT2R in regulating angiogenesis during pregnancy has never been studied. This study examines whether or not AT2R activation induces angiogenesis and, if so, what mechanisms are involved. To this end, we used primary human uterine artery endothelial cells (hUAECs) isolated from pregnant and nonpregnant women undergoing hysterectomy. The present study shows that Compound 21, a selective AT2R agonist, induced proliferation of pregnant-hUAECs, but not nonpregnant-hUAECs, in a concentration-dependent manner, and that this C21-induced mitogenic effect was blocked by PD123319, a selective AT2R antagonist. The mitogenic effects induced by C21 were inhibited by blocking JNK—but not ERK, PI3K, and p38—signaling pathways. In addition, C21 concentration dependently increased cell migration and capillary-like tube formation in pregnant-hUAECs. The membrane-based antibody array showed that C21 increased expression of multiple angiogenic proteins, including EGF, bFGF, leptin, PLGF, IGF-1, and angiopoietins. Our qPCR analysis demonstrates that C21-induced increase in expression of these angiogenic proteins correlates with a proportional increase in mRNA expression, indicating that AT2R activates angiogenic proteins at the transcriptional level. In summary, the present study shows that AT2R activation induces angiogenesis of hUAECs in a pregnancy-specific manner through JNK-mediated pathways with associated transcriptional upregulation of multiple proangiogenic proteins.

Placental growth factor level is correlated with intrapartum fetal heart rate findings

Objective

Here, we tested the correlation between maternal placental growth factor (PlGF) and fetal heart rate (FHR) monitoring findings.

Methods

We included 35 women with single pregnancies from 35 to 42 weeks of gestation who were hospitalized owing to onset of labor. Blood samples were collected at the start of labor. Intrapartum FHR monitoring parameters included total deceleration area, average deceleration area (mean deceleration area per 10 min), and five-tier classification level.

Results

Of the 35 women, 26 (74%) had vaginal delivery and 9 (26%) had cesarean section. After excluding 2 women who had cesarean section for arrest of labor, we analyzed 26 women who had vaginal delivery (VD group) and 7 who had cesarean section for fetal indications (CSF group). PlGF level was significantly higher in the VD group (157 ± 106 pg/ml) than in the CSF group (74 ± 62 pg/ml) (P = 0.03). There were no significant correlations between PlGF and total (r = -0.07) or average (r = -0.08) deceleration area.　There was a significant negative correlation (r = -0.42, P = 0.01) between PlGF and the percentage of level 3 or higher in the five-level classification.

Conclusion

PlGF was correlated with FHR monitoring findings and might be a promising biomarker of intrapartum fetal function.

Vaginal Exposure to Candida albicans During Early Gestation Results in Adverse Pregnancy Outcomes via Inhibiting Placental Development

Vulvovaginal candidiasis (VVC) is considered the second most common cause of vaginitis after bacterial vaginosis and the most common lower genital tract infection during pregnancy. Candida albicans (C. albicans), an opportunistic pathogen, is the major species causing VVC. Recently, increasing researches have shown that lower reproductive tract infection during pregnancy can lead to various adverse pregnancy outcomes. However, the underlying mechanisms are not fully understood. Hence, we successfully established a mouse model of vaginal C. albicans infection and characterized the adverse pregnancy outcomes. C. albicans infection strikingly increased abortion rate and decreased litter size. Further analysis of placental development demonstrated that placental structure was abnormal, including that the area of spongiotrophoblast (Spo) and labyrinth (Lab) was reduced, and the formation of placental vessel was decreased in Lab zone. Accordingly, the expression of marker genes during placental development was downregulated. Collectively, the above findings revealed that vaginal C. albicans infection during pregnancy can inhibit placental development and ultimately lead to adverse pregnancy outcomes. This study enhances our comprehension of the effect of VVC on pregnancy, and placental dysplasia as a feasible orientation to explore VVC during pregnancy.

Developmental Vitamin D Deficiency in Pregnant Rats Does Not Induce Preeclampsia

Preeclampsia is a pregnancy disorder characterized by hypertension. Epidemiological studies have associated preeclampsia with an increased risk of neurodevelopmental disorders in offspring, such as autism and schizophrenia. Preeclampsia has also been linked with maternal vitamin D deficiency, another candidate risk factor also associated with autism. Our laboratory has established a gestational vitamin-D-deficient rat model that shows consistent and robust behavioural phenotypes associated with autism- and schizophrenia-related animal models. Therefore, we explored here whether this model also produces preeclampsia as a possible mediator of behavioural phenotypes in offspring. We showed that gestational vitamin D deficiency was not associated with maternal blood pressure or proteinuria during late gestation. Maternal and placental angiogenic and vasculogenic factors were also not affected by a vitamin-D-deficient diet. We further showed that exposure to low vitamin D levels did not expose the placenta to oxidative stress. Overall, gestational vitamin D deficiency in our rat model was not associated with preeclampsia-related features, suggesting that well-described behavioural phenotypes in offspring born to vitamin-D-deficient rat dams are unlikely to be mediated via a preeclampsia-related mechanism.

Transcriptomic analysis of primate placentas and novel rhesus trophoblast cell lines informs investigations of human placentation

BACKGROUND

Proper placentation, including trophoblast differentiation and function, is essential for the health and well-being of both the mother and baby throughout pregnancy. Placental abnormalities that occur during the early stages of development are thought to contribute to preeclampsia and other placenta-related pregnancy complications. However, relatively little is known about these stages in humans due to obvious ethical and technical limitations. Rhesus macaques are considered an ideal surrogate for studying human placentation, but the unclear translatability of known human placental markers and lack of accessible rhesus trophoblast cell lines can impede the use of this animal model.

RESULTS

Here, we performed a cross-species transcriptomic comparison of human and rhesus placenta and determined that while the majority of human placental marker genes (HPGs) were similarly expressed, 952 differentially expressed genes (DEGs) were identified between the two species. Functional enrichment analysis of the 447 human-upregulated DEGs, including ADAM12, ERVW-1, KISS1, LGALS13, PAPPA2, PGF, and SIGLEC6, revealed over-representation of genes implicated in preeclampsia and other pregnancy disorders. Additionally, to enable in vitro functional studies of early placentation, we generated and thoroughly characterized two highly pure first trimester telomerase (TERT) immortalized rhesus trophoblast cell lines (iRP-D26 and iRP-D28A) that retained crucial features of isolated primary trophoblasts.

CONCLUSIONS

Overall, our findings help elucidate the molecular translatability between human and rhesus placenta and reveal notable expression differences in several HPGs and genes implicated in pregnancy complications that should be considered when using the rhesus animal model to study normal and pathological human placentation.

A crossroad between placental and tumor biology: What have we learnt?

Placenta in certain species including the human has evolved as a highly invasive tumor-like organ invading the uterus aned its vasculature to derive oxygen and nutrients for the fetus and exchange waste products. While several excellent reviews have been written comparing hemochorial placentation with tumors, no comprehensive review is available dealing with mechanistic insights into what makes them different, and what tumor biologists can learn from placental biologists, and vice versa. In this review, we analyze the structure-function relationship of the human placenta, emphasizing the functional need of the spatio-temporally orchestrated trophoblast invasiveness for fetal development and growth, and pathological consequences of aberrant invasiveness for fetal and maternal health. We then analyze similarities and differences between the placenta and invasive tumors in terms of hallmarks of cancer, some key molecules regulating their invasive functions, and how placental cancers (choriocarcinomas) or other cancers become refractory or even addicted to these invasion-restraining molecules. We cite in vitro models of human trophoblast and choriocarcinoma cell lines utilized to study mechanisms in normal placental development as well as those responsible for tumor progression. We discuss the pathobiology of hyper-invasive placentas and show thattrophoblastic neoplasias are a unique and heterogeneous class of tumors. We delve into the questions as to why metastasis from other organs rarely occurs at the placental site and whether pregnancy makes the mother more or less vulnerable to cancer-related morbidity/mortality. We attempt to compare trophoblast stem cells and cancer stem cells. Finally, we leave the readers with some thoughts as foods of future investigations.

Metastatic Dissemination Mimicked in a Multicellular Transwell Assay

Tumor progression and metastasis are multistep processes that are critically dependent on the interaction of metastasizing tumor cells with other cells of the local microenvironment. Mimicking the single steps of the metastatic cascade in vitro is therefore challenging when investigating not only tumor cell behavior alone but also cellular crosstalk between different cell populations. In particular, the crosstalk of tumor cells with pericytes and endothelial cells when accessing the bloodstream is of great importance for successful intravasation and metastatic dissemination. To examine metastatic intravasation and analyze the interaction of tumor cells with pericytes, which reside within the basement membrane and endothelial cells, aligning the vessel wall, we have designed a 3D in vitro transwell assay mimicking tumor cell intravasation into a vessel. Modifying the Boyden chamber transwell assay by seeding first an endothelial cell layer onto the transwell membrane and covering it with pericytes before adding the tumor cells allows us to investigate the role of pericytes and endothelial cells on tumor cell intravasation and at the same time to study their crosstalk at the molecular level and how this interaction influences tumor cell behavior. It further allows the manipulation of the system for proof-of-principle experimentation.

PlGF Immunological Impact during Pregnancy

During pregnancy, the mother’s immune system has to tolerate the persistence of paternal alloantigens without affecting the anti-infectious immune response. Consequently, several mechanisms aimed at preventing allograft rejection, occur during a pregnancy. In fact, the early stages of pregnancy are characterized by the correct balance between inflammation and immune tolerance, in which proinflammatory cytokines contribute to both the remodeling of tissues and to neo-angiogenesis, thus, favoring the correct embryo implantation. In addition to the creation of a microenvironment able to support both immunological privilege and angiogenesis, the trophoblast invades normal tissues by sharing the same behavior of invasive tumors. Next, the activation of an immunosuppressive phase, characterized by an increase in the number of regulatory T (Treg) cells prevents excessive inflammation and avoids fetal immuno-mediated rejection. When these changes do not occur or occur incompletely, early pregnancy failure follows. All these events are characterized by an increase in different growth factors and cytokines, among which one of the most important is the angiogenic growth factor, namely placental growth factor (PlGF). PlGF is initially isolated from the human placenta. It is upregulated during both pregnancy and inflammation. In this review, we summarize current knowledge on the immunomodulatory effects of PlGF during pregnancy, warranting that both innate and adaptive immune cells properly support the early events of implantation and placental development. Furthermore, we highlight how an alteration of the immune response, associated with PlGF imbalance, can induce a hypertensive state and lead to the pre-eclampsia (PE).

Effects of NRP1 on angiogenesis and vascular maturity in endothelial cells are dependent on the expression of SEMA4D

Angiogenesis and vascular maturation play important roles in tumorigenesis and tumor development. The expression of neuropilin 1 (NRP1) is closely associated with angiogenesis in tumors; however, the molecular mechanisms of action in angiogenesis and tumor maturation, as well as the potential clinical value of NRP1 remain unclear. The importance of NRP1 expression in tumor progression was determined using The Cancer Genome Atlas (TCGA) database analysis. Gain- and loss-of-function experiments of NRP1 were performed in vascular endothelial cells (ECs) to investigate the functions in angiogenesis. CCK-8, flow cytometry, Transwell experiments and a series of in vitro experiments were used to detect cell functions. A combination of angiogenesis antibody arrays and RNA-Seq analyses were performed to reveal the proangiogenic mechanisms of action. The function of semaphorin 4D (SEMA4D) was also investigated separately. NRP1 mRNA levels were significantly increased in primary tumors compared with normal tissues based on TCGA data (P<0.01) and were associated with tumor development in patients. Gain- and loss-of-function experiments highlighted the function of NRP1 in promoting EC proliferation, motility and capillary-like tube formation and in reducing apoptosis. NRP1 overexpression led to significantly decreased EC markers (PECAM-1, angiogenin, PIGF and MMP-9) expression levels and reduced the vascular maturity. MAPK7, TPM1, RRBP1, PTPRK, HSP90A, PRKD2, PFKFB3, RGS4 and SPARC were revealed to play important roles in this process. SEMA4D was revealed to be a key protein associated with NRP1 in ECs. These data indicated that NRP1-promoted angiogenesis may be induced at the cost of reducing maturity of the ECs. NRP1 may also be a therapeutic target for antiangiogenic strategies and a candidate prognostic marker for tumors.

Effect of Placental Growth Factor on Trophoblast-Endothelial Cell Interactions In Vitro

Placental growth factor (PlGF) is an important angiogenic factor which has an emerging role in the clinical management of suspected preeclampsia. The role of PlGF in normal placental development is not completely understood and it is uncertain whether PlGF influences trophoblast and endothelial cell interactions central to uterine spiral artery remodelling, especially in variable oxygen conditions. A two-cell model of endovascular invasion was used. Tissue culture plates were coated with Matrigel™, on which fluorescent-labelled uterine microvascular endothelial cells (1 × 10⁵/well) and HTR8/SVNeo cells were co-cultured (1 × 10⁵/well) for 20 h. Co-cultures were treated with recombinant human PlGF (rhPlGF) (10 or 100 ng/mL) and incubated at either 21% O₂ or 2% O₂. Images were captured by fluorescence microscopy and analysed using ImageJ (n = 7). Data was analysed using SPSSv24. Treatment with rhPlGF did not improve integration in co-cultures irrespective of oxygen conditions but increased proliferation in 2% O₂ of both trophoblast and endothelial cells. Expression of angiogenic factors VEGF, sFLT-1, PlGF and CXCL12 in both co-cultures and in isolated trophoblast cells was not altered by rhPlGF treatment. Expression of TLR-3 mRNA in co-cultures was increased by rhPlGF 100 ng/mL at 21% O₂ (p = 0.03). PlGF contributes to trophoblast and endothelial cell proliferation in the setting of physiological hypoxia but does not influence trophoblast and endothelial cell interactions in an in vitro model of spiral artery remodelling. Upregulation of TLR-3 expression in co-cultures may indicate a role for PlGF in the placental inflammatory response.

Heparan Sulfate in the Tumor Microenvironment

The biology of tumor cells strictly depends on their microenvironment architecture and composition, which controls the availability of growth factors and signaling molecules. Thus, the network of glycosaminoglycans, proteoglycans, and proteins known as extracellular matrix (ECM) that surrounds the cells plays a central role in the regulation of tumor fate. Heparan sulfate (HS) and heparan sulfate proteoglycans (HSPGs) are highly versatile ECM components that bind and regulate the activity of growth factors, cell membrane receptors, and other ECM molecules. These HS binding partners modulate cell adhesion, motility, and proliferation that are processes altered during tumor progression. Modification in the expression and activity of HS, HSPGs, and the respective metabolic enzymes results unavoidably in alteration of tumor cell microenvironment. In this light, the targeting of HS structure and metabolism is potentially a new tool in the treatment of different cancer types.

The Impact of Infection in Pregnancy on Placental Vascular Development and Adverse Birth Outcomes

Healthy fetal development is dependent on nutrient and oxygen transfer via the placenta. Optimal growth and function of placental vasculature is therefore essential to support in utero development. Vasculogenesis, the de novo formation of blood vessels, and angiogenesis, the branching and remodeling of existing vasculature, mediate the development and maturation of placental villi, which form the materno-fetal interface. Several lines of evidence indicate that systemic maternal infection and consequent inflammation can disrupt placental vasculogenesis and angiogenesis. The resulting alterations in placental hemodynamics impact fetal growth and contribute to poor birth outcomes including preterm delivery, small-for-gestational age (SGA), stillbirth, and low birth weight (LBW). Furthermore, pathways involved in maternal immune activation and placental vascularization parallel those involved in normal fetal development, notably neurovascular development. Therefore, immune-mediated disruption of angiogenic pathways at the materno-fetal interface may also have long-term neurological consequences for offspring. Here, we review current literature evaluating the influence of maternal infection and immune activation at the materno-fetal interface and the subsequent impact on placental vascular function and birth outcome. Immunomodulatory pathways, including chemokines and cytokines released in response to maternal infection, interact closely with the principal pathways regulating placental vascular development, including the angiopoietin-Tie-2, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) pathways. A detailed mechanistic understanding of how maternal infections impact placental and fetal development is critical to the design of effective interventions to promote placental growth and function and thereby reduce adverse birth outcomes.

Maternal High-Fat Diet Consumption and Chronic Hyperandrogenemia Are Associated With Placental Dysfunction in Female Rhesus Macaques

The risk of adverse perinatal outcomes with maternal polycystic ovary syndrome may differ among hyperandrogenic and nonhyperandrogenic phenotypes and is likely modulated by maternal obesity and diet. The relative contribution of maternal hyperandrogenism and nutritional status to placental dysfunction is unknown. Female rhesus macaques (N = 39) were assigned at puberty to one of four treatment groups: subcutaneous cholesterol implants and a standard chow diet (controls); testosterone (T) implants and a normal diet; cholesterol implants and a high-fat, Western-style diet (WSD); and testosterone implants in combination with a high-fat diet. After 3.5 years of treatment, contrast-enhanced and Doppler ultrasound analyses of placental blood flow were performed for a representative subset of animals from each treatment group during pregnancy, and placental architecture assessed with stereological analysis. Placental growth factors, cellular nutrient sensors, and angiogenic markers were measured with ELISA and Western blotting. WSD consumption was associated with a 30% increase in placental flux rate relative to that in animals receiving a normal diet. T and WSD treatments were each independently associated with increased villous volume, and T also was associated with an ∼ 40% decrease fetal capillary volume on stereological analysis. T treatment was associated with significantly increased mTOR and SOCS3 expression. WSD consumption was associated with decreased GLUT1 expression and microvillous membrane localization. Hyperandrogenemic and nonhyperandrogenemic phenotypes are associated with altered placental angiogenesis, nutrient sensing, and glucose transport. WSD and T appear to have distinct effects on vascular impedance and capillary angiogenesis.

Regulation of Placental Extravillous Trophoblasts by the Maternal Uterine Environment

During placentation invasive extravillous trophoblasts (EVTs) migrate into the maternal uterus and modify its vessels. In particular, remodeling of the spiral arteries by EVTs is critical for adapting blood flow and nutrient transport to the developing fetus. Failures in this process have been noticed in different pregnancy complications such as preeclampsia, intrauterine growth restriction, stillbirth, or recurrent abortion. Upon invasion into the decidua, the endometrium of pregnancy, EVTs encounter different maternal cell types such as decidual macrophages, uterine NK (uNK) cells and stromal cells expressing a plethora of growth factors and cytokines. Here, we will summarize development of the EVT lineage, a process occurring independently of the uterine environment, and formation of its different subtypes. Further, we will discuss interactions of EVTs with arteries, veins and lymphatics and illustrate how the decidua and its different immune cells regulate EVT differentiation, invasion and survival. The present literature suggests that the decidual environment and its soluble factors critically modulate EVT function and reproductive success.

Hypertension in Pregnancy: Defining Blood Pressure Goals and the Value of Biomarkers for Preeclampsia

Hypertensive disorders in pregnancy have been the cause of much clinical dilemma, affecting up to 10 % of all pregnancies. The precise blood pressure to achieve in a pregnant woman is usually a battle between minimizing end organ damage to the mother and providing adequate perfusion to the placenta and the fetus. This predicament is becoming more, not less, frequent as maternal ages increase in high resource nations. Biomarkers to predict preeclampsia, a subcategory of hypertension in pregnancy, have always been elusive. The discovery of angiogenic factors relevant to preeclampsia in the last decade, however, has propelled much needed research, both in the basic science and clinical arenas. In this review, we summarize the latest clinical studies and international guidelines on blood pressure goals in pregnancy, and discuss the most promising of biomarkers to predict or diagnose preeclampsia.

Placental growth factor and pre-eclampsia

Placental growth factor (PlGF) is an increasingly important molecule in the prediction, diagnosis and treatment of pre-eclampsia. It has pro-angiogenic effects on the feto-placental circulation and supports trophoblast growth. Mechanisms by which PlGF expression is regulated continue to be investigated. Low circulating PlGF precedes the manifestation of clinical disease in pre-eclamptic pregnancies and intrauterine growth restriction. This suggests that low PlGF is a marker of abnormal placentation, but it remains uncertain whether this is a cause or consequence. Prediction of pre-eclampsia using PlGF is promising and may assist in the targeting of resources to women at highest risk of adverse pregnancy outcomes. Promisingly, experimental animal models of pre-eclampsia have been successfully treated with supplemental PlGF. Treatment of pre-eclampsia with PlGF is a potential therapeutic option requiring further exploration. This review focuses specifically on the role of PlGF in normal and pathological placental development and in the clinical management of pre-eclampsia.

DLX3 interacts with GCM1 and inhibits its transactivation-stimulating activity in a homeodomain-dependent manner in human trophoblast-derived cells

The placental transcription factors Distal-less 3 (DLX3) and Glial cell missing-1 (GCM1) have been shown to coordinate the specific regulation of PGF in human trophoblast cell lines. While both factors independently have a positive effect on PGF gene expression, when combined, DLX3 acts as an antagonist to GCM. Despite this understanding, potential mechanisms accounting for this regulatory interaction remain unexplored. We identify physical and functional interactions between specific domains of DLX3 and GCM1 in human trophoblast-derived cells by performing immunoprecipitation and mammalian one hybrid assays. Studies revealed that DLX3 binding reduced the transcriptional activity of GCM1, providing a mechanistic explanation of their functional antagonism in regulating PGF promoter activity. The DLX3 homeodomain (HD) was essential for DLX3-GCM1 interaction, and that the HD together with the DLX3 amino- or carboxyl-terminal domains was required for maximal inhibition of GCM1. Interestingly, a naturally occurring DLX3 mutant that disrupts the carboxyl-terminal domain leading to tricho-dento-osseous syndrome in humans displayed activities indistinguishable from wild type DLX3 in this system. Collectively, our studies demonstrate that DLX3 physically interacts with GCM1 and inhibits its transactivation activity, suggesting that DLX3 and GCM1 may form a complex to functionally regulate placental cell function through modulation of target gene expression.

Hypoxia and HIF pathway in cancer and the placenta

In this review we note that the placenta and cancer both develop in microenvironments in which there are gradients of oxygen availability. Whilst fundamentally different in that placental development is organised and physiological whilst cancer is chaotic and pathological, there are similarities in their respective capacities to proliferate, invade adjacent tissues, generate a blood supply and avoid rejection by the immune system. We provide a brief description of the hypoxia-inducible factor (HIF) pathway and indicate the ways by which HIF activity can be regulated to achieve oxygen homeostasis. We then exemplify the potential role of the HIF pathway in contributing to those functions shared between the placenta and cancer through effects on cellular proliferation, cell death, angiogenesis, blood vessel co-option, vascular mimicry, cell adhesion molecules, secretion of matrix metalloproteinases, antigen presentation mechanisms and immunosuppressive factors. We advocate future studies to explore these similarities and differences in the hope of improving our understanding of both systems and hence treatments of placental disorders and cancer.

Dlx3 and GCM-1 functionally coordinate the regulation of placental growth factor in human trophoblast-derived cells

Placental growth factor (PGF) is abundantly expressed by trophoblast cells within human placentae and is important for trophoblast development and placental vascularization. Circulating maternal serum levels of PGF are dynamically upregulated across gestation in normal pregnancies, whereas low circulating levels and placental production of PGF have been implicated in the pathogenesis of preeclampsia and other gestational diseases. However, the underlying molecular mechanism of regulating PGF expression in the human placenta remains poorly understood. In this study, we demonstrated that transcription factors Distal-less 3 (DLX3) and Glial cell missing-1 (GCM1) were both sufficient and required for PGF expression in human trophoblast-derived cells by overexpression and knockdown approaches. Surprisingly, while DLX3 and GCM1 were both positive regulators of PGF, co-overexpression of DLX3 and GCM1 led to an antagonist effect on PGF expression on the endogenous gene and a luciferase reporter. Further, deletion and site-directed mutagenesis studies identified a novel regulatory element on the PGF promoter mediating both DLX3- and GCM1-dependent PGF expression. This regulatory region was also found to be essential for the basal activity of the PGF promoter. Finally, Chromatin-immunoprecipitation (ChIP) assays revealed colocalization of DLX3 and GCM1 at the identified regulatory region on the PGF promoter. Taken together, our studies provide important insights into intrinsic regulation of human placental PGF expression through the functional coordination of DLX3 and GCM1, and are likely to further the understanding of pathogenesis of PGF dysregulation in preeclampsia and other disease conditions.

Triazole fungicide tebuconazole disrupts human placental trophoblast cell functions

Triazole fungicides are one of the top ten classes of current-use pesticides. Although exposure to triazole fungicides is associated with reproductive toxicity in mammals, limited information is available regarding the effects of triazole fungicides on human placental trophoblast function. Tebuconazole (TEB) is a common triazole fungicide that has been extensively used for fungi control. In this work, we showed that TEB could reduce cell viability, disturb normal cell cycle distribution and induce apoptosis of human placental trophoblast cell line HTR-8/SVneo (HTR-8). Bcl-2 protein expression decreased and the level of Bax protein increased after TEB treatment in HTR-8 cells. The results demonstrated that this fungicide induced apoptosis of trophoblast cells via mitochondrial pathway. Importantly, we found that the invasive and migratory capacities of HTR-8 cells decreased significantly after TEB administration. TEB altered the expression of key regulatory genes involved in the modulation of trophoblast functions. Taken together, TEB suppressed human trophoblast invasion and migration through affecting the expression of protease, hormones, angiogenic factors, growth factors and cytokines. As the invasive and migratory abilities of trophoblast are essential for successful placentation and fetus development, our findings suggest a potential risk of triazole fungicides to human pregnancy.

The Placenta as an Organ and a Source of Stem Cells and Extracellular Matrix: A Review

The placenta is a temporal, dynamic and diverse organ with important immunological features that facilitate embryonic and fetal development and survival, notwithstanding the fact that several aspects of its formation and function closely resemble tumor progression. Placentation in mammals is commonly used to characterize the evolution of species, including insights into human evolution. Although most placentas are discarded after birth, they are a high-yield source for the isolation of stem/progenitor cells and are rich in extracellular matrix (ECM), representing an important resource for regenerative medicine purposes. Interactions among cells, ECM and bioactive molecules regulate tissue and organ generation and comprise the foundation of tissue engineering. In the present article, differences among several mammalian species regarding the placental types and classifications, phenotypes and potency of placenta-derived stem/progenitor cells, placental ECM components and current placental ECM applications were reviewed to highlight their potential clinical and biomedical relevance.

Mechanisms of trophoblast migration, endometrial angiogenesis in preeclampsia: The role of decorin

The objective of the present review is to synthesize the information on the cellular and molecular players responsible for maintaining a homeostatic balance between a naturally invasive human placenta and the maternal uterus in pregnancy; to review the roles of decorin (DCN) as a molecular player in this homeostasis; to list the common maladies associated with a break-down in this homeostasis, resulting from a hypo-invasive or hyper-invasive placenta, and their underlying mechanisms. We show that both the fetal components of the placenta, represented primarily by the extravillous trophoblast, and the maternal component represented primarily by the decidual tissue and the endometrial arterioles, participate actively in this balance. We discuss the process of uterine angiogenesis in the context of uterine arterial changes during normal pregnancy and preeclampsia. We compare and contrast trophoblast growth and invasion with the processes involved in tumorigenesis with special emphasis on the roles of DCN and raise important questions that remain to be addressed. Decorin (DCN) is a small leucine-rich proteoglycan produced by stromal cells, including dermal fibroblasts, chondrocytes, chorionic villus mesenchymal cells and decidual cells of the pregnant endometrium. It contains a 40 kDa protein core having 10 leucine-rich repeats covalently linked with a glycosaminoglycan chain. Biological functions of DCN include: collagen assembly, myogenesis, tissue repair and regulation of cell adhesion and migration by binding to ECM molecules or antagonising multiple tyrosine kinase receptors (TKR) including EGFR, IGF-IR, HGFR and VEGFR-2. DCN restrains angiogenesis by binding to thrombospondin-1, TGFβ, VEGFR-2 and possibly IGF-IR. DCN can halt tumor growth by antagonising oncogenic TKRs and restraining angiogenesis. DCN actions at the fetal-maternal interface include restraint of trophoblast migration, invasion and uterine angiogenesis. We demonstrate that DCN overexpression in the decidua is associated with preeclampsia (PE); this may have a causal role in PE by compromising endovascular differentiation of the trophoblast and uterine angiogenesis, resulting in poor arterial remodeling. Elevated DCN level in the maternal blood is suggested as a potential biomarker in PE.

Investigating the effect of excess caffeine exposure on placental angiogenesis using chicken 'functional' placental blood vessel network

It is now known that over-consumption of caffeine by pregnant mothers could have detrimental effects on normal fetal development. However, it remains obscure how caffeine's harmful effect impacts directly or indirectly on the developing embryo/fetus through damaging placenta development. In this study, we demonstrated the morphological similarities between the yolk sac and chorioallantoic membranes (CAM) of chick embryos and the villi of the mammalian placenta. Using the chick yolk sac and the CAM as a model, we found that 5-15 µmol per egg of caffeine exposure inhibited angiogenesis. Under the same condition, cell proliferation in extraembryonic mesoderm was reduced while apoptosis was enhanced. Semi-quantitative RT-PCR analysis revealed that caffeine treatment down-regulated VEGF, VEGFR2, PIGF, IGF2 and NRP1 expression, but up-regulated Ang1 and Ang2 expression. We performed in situ hybridization to show VE-cadherin expression and as to demonstrate the blood vessels in the CAM and yolk sac membranes. This distribution of the VE-cadherin(+) blood vessels was determined to be reduced after caffeine treatment. Furthermore, MDA activity was induced after caffeine exposure, but GSH-PX activity was inhibited after caffeine exposure; SOD activity was unchanged as compared with the control. In summary, our results suggest that caffeine exposure could negatively impact on angiogenesis in the chick yolk sac and CAM by targeting angiogenesis-related genes. Some of these genes are also involved in regulating excess ROS generation. The results implied that the negative impact of caffeine on fetal development was partly attributed to impaired placental angiogenesis.

Combination of PAPPA, fhCGβ, AFP, PlGF, sTNFR1, and Maternal Characteristics in Prediction of Early-onset Preeclampsia

OBJECTIVE

To evaluate the efficacy of first-trimester markers-pregnancy-associated plasma protein A (PAPPA), free human chorionic gonadotropin β (fhCGβ), alpha-fetoprotein (AFP), placental growth factor (PlGF), and soluble tumor necrosis factor receptor-1 (sTNFR1) together with maternal characteristics (MC) for prediction of early-onset preeclampsia (EOPE).

METHODS

During 2005-2010, the abovementioned biomarkers were analyzed with logistic regression analysis in 64 EOPE and 752 control subjects to determine whether these biomarkers separately and in combination with MC would predict development of EOPE.

RESULTS

PAPPA, fhCGβ, and PlGF levels were lower, whereas AFP and sTNFR1 levels were higher in mothers with EOPE compared to controls. The combination of all markers with MC (age, weight, and smoking status) detected 48% of the mothers with EOPE, with a 10% false-positive rate (FPR).

CONCLUSIONS

First-trimester maternal serum levels of PAPPA, fhCGβ, AFP, PlGF, and sTNFR1, together with MC, are predictive of development of subsequent EOPE. These markers, along with MC, form a suitable panel for predicting EOPE.

Increased angiogenic factor secretion by decidual natural killer cells from pregnancies with high uterine artery resistance alters trophoblast function

STUDY QUESTION

Are the concentrations of factors secreted by decidual natural killer (dNK) cells from pregnancies at high risk of poor spiral artery remodelling different to those secreted from pregnancies at low risk?

SUMMARY ANSWER

Expression levels of PLGF, sIL-2R, endostatin and angiogenin were significantly increased by dNK cells from high-risk pregnancies, and angiogenin and endostatin were found to alter trophoblast function.

WHAT IS KNOWN ALREADY

During early pregnancy, maternal uterine spiral arteries are remodelled from small diameter, low-flow, high-resistance vessels into larger diameter, higher flow vessels, with low-resistance. This change is essential for the developing fetus to obtain sufficient oxygen and nutrients. dNK cells have been implicated in this process.

STUDY DESIGN, SIZE, DURATION

dNK cells were isolated from first trimester terminations of pregnancies (obtained with local ethical approval) screened for normal- or high-resistance index, indicative of cases least (<1%) and most (>21%) likely to have developed pre-eclampsia had the pregnancy not been terminated (n = 18 each group). Secreted factors and the effects of these on the trophoblast cell line, SGHPL-4, were assessed in vitro.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A multiplex assay was used to assess dNK cell-secreted factors. SGHPL-4 cell functions were assessed using time-lapse microscopy, 3D invasion assays, endothelial-like tube formation ability and western blot analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

The expression levels of PLGF (P < 0.01), sIL-2R (P < 0.01), endostatin (P < 0.05) and angiogenin (P < 0.05) were significantly increased by dNK cells from high-risk pregnancies. Endostatin significantly decreased SGHPL-4 invasion (P < 0.05), SGHPL-4 tube formation (P < 0.05) and SGHPL-4 Akt^ser473 phosphorylation (P < 0.05). Angiogenin significantly decreased SGHPL-4 invasion (P < 0.05), but increased SGHPL-4 tube formation (P < 0.01) and decreased SGHPL-4 Akt^ser473 phosphorylation (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

The culture of dNK cells and protein concentrations in vitro may not fully represent the in vivo situation. Although SGHPL-4 cells are extravillous trophoblast derived, further studies would be needed to confirm the roles of angiogenin and endostatin in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

The altered expression of secreted factors of dNK cells may contribute to pregnancy disorders associated with poor spiral artery remodelling.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Wellcome Trust (project reference 091550). R.F. was a recipient of a PhD studentship from the Division of Biomedical Sciences, St. George's, University of London. The authors have no conflict of interests.

Cytokines as key players in the pathophysiology of preeclampsia

Preeclampsia (PE) is an important, common, and dangerous complication of pregnancy; it causes maternal and perinatal illness and is responsible for a high proportion of maternal and infant deaths. PE is associated with increased blood pressure and proteinuria, with a whole host of other potentially serious complications in the mother and fetus. The maternal syndrome in PE is primarily that of generalized dysfunction of the maternal endothelium, and this generalized endothelial dysfunction appears to be part of an exaggerated systemic inflammatory response that involves maternal leukocytes and proinflammatory cytokines. This review examines evidence that points to a significant role for the maternal immune system; inadequate trophoblast invasion of spiral arteries initiates ischemia and hypoxia in the placenta, resulting in an increased release of proinflammatory cytokines in the placenta. Placental ischemia and hypoxia also cause the enhanced release of trophoblast microparticles into the maternal circulation which stimulates increased induction of proinflammatory cytokines and the activation of maternal endothelial cells. This activation results in a systemic, diffuse endothelial cell dysfunction which is the fundamental pathophysiological feature of this syndrome. Recent evidence also supports important roles for proinflammatory cytokines in hypertension, proteinuria, and edema which are characteristic features of PE.

Response gene to complement 32 deficiency causes impaired placental angiogenesis in mice

AIMS

The objectives of this study are to determine the role of response gene to complement 32 (RGC-32) in the placental angiogenesis during pregnancy and explore the underlying mechanisms.

METHODS AND RESULTS

RGC-32-deficient (RGC32(-/-)) mice were generated from C57BL/6 embryonic stem cells with deletion of exon 2 and 3 of the RGC-32 gene. Most of the RGC32(-/-) mice can survive. However, their body sizes were much smaller compared with their wild-type littermates when they were born. By examining the embryo development and placentas at 16.5 days post-coitum, we found that RGC32(-/-) embryos and foetal placentas were significantly smaller than the wild-type. Further analysis showed that the labyrinth zone of RGC32(-/-) placenta was smaller with defective angiogenesis. Mechanistically, vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) and placental growth factor (PlGF) were significantly down-regulated in RGC32(-/-) placentas, suggesting that VEGFR2 and PlGF may mediate RGC-32 function in placental angiogenesis. Indeed, knockdown of RGC-32 by shRNA inhibited VEGF-induced endothelial cell proliferation, migration, and tube formation while blocking VEGFR2 expression. RGC-32 appeared to regulate VEGFR2 expression via activation of NF-kB. Moreover, RGC-32 regulated trophoblasts proliferation via control of PlGF expression.

CONCLUSION

Absence of RGC-32 caused foetal growth restriction through interrupting the placental angiogenesis, which was due to the decrease in VEGFR2 expression through the NF-kB-dependent pathway in endothelial cells and PlGF expression in trophoblasts.

Framing postpartum hemorrhage as a consequence of human placental biology: an evolutionary and comparative perspective

Postpartum hemorrhage (PPH), the leading cause of maternal mortality worldwide, is responsible for 35 percent of maternal deaths. Proximately, PPH results from the failure of the placenta to separate from the uterine wall properly, most often because of impairment of uterine muscle contraction. Despite its prevalence and its well-described clinical manifestations, the ultimate causes of PPH are not known and have not been investigated through an evolutionary lens. We argue that vulnerability to PPH stems from the intensely invasive nature of human placentation. The human placenta causes uterine vessels to undergo transformation to provide the developing fetus with a high plane of maternal resources; the degree of this transformation in humans is extensive. We argue that the particularly invasive nature of the human placenta increases the possibility of increased blood loss at parturition. We review evidence suggesting PPH and other placental disorders represent an evolutionarily novel condition in hominins.

Leukaemia inhibitory factor mediated proliferation of HTR-8/SVneo trophoblast cells is dependent on activation of extracellular signal-regulated kinase 1/2

Leukaemia inhibitory factor (LIF) is one of the cytokines that is indispensable for embryo implantation. The aim of the present study was to investigate the role of activation of extracellular signal-regulated kinase (ERK) 1/2 in LIF-mediated proliferation of HTR-8/SVneo cells. Stimulation of HTR-8/SVneo cells with LIF (50 ng mL(-1)) resulted in an increase in cell proliferation (P < 0.05) via increased transition of cells to the G(2)/M phase of cell cycle. Stimulation with LIF resulted in the activation of both signal transducer and activator of transcription (STAT) 3 Tyr(705) and ERK1/2, but inhibition of ERK1/2 signalling by pretreatment of cells with U0126 (10 µM) for 2h resulted in abrogation of LIF-mediated increases in G(2)/M transition, with a significant decrease (P < 0.05) in absolute cell numbers compared with control. Although STAT3 silencing had no effect on LIF-dependent proliferation of HTR-8/SVneo cells, it did result in an increase in cell apoptosis, which increased further upon inhibition of ERK1/2 activation irrespective of LIF stimulation. Stimulation of cells with LIF increased the Bcl-2/Bax ratio, whereas ERK1/2 inhibition decreased the Bcl-2/Bax ratio, even after LIF stimulation. Hence, it can be inferred that ERK1/2 activation is essential for LIF-mediated increases in proliferation and that both STAT3 and ERK1/2 activation are important for the survival of HTR-8/SVneo cells.

Comparative expression profiles for KiSS-1 and REN genes in preeclamptic and healthy placental tissues

OBJECTIVE

The aim of the present work was to look at differences in the placental tissue expression of KiSS-1 and REN genes from preeclamptic and healthy pregnant women, that could account for a possible synergistic function for both genes in the pathogenesis of preeclampsia.

STUDY DESIGN

This case-control study involved 27 preeclamptic women and 27 normoevolutive pregnant women. cDNA was obtained from placental tissue to carry out qPCR for both KiSS-1 and REN genes in order to compare mRNA expression levels in the studied groups. Statistical analysis showed expression differences that correlate with clinical and/or biochemical variables.

RESULTS

Higher expression for KiSS-1 in PEE vs. control woman (p=0.001) was observed, whereas no difference was observed for REN expression (p=0.300) when all the subjects were included. However, REN expression was significant higher when the samples were stratified according to preeclampsia severity. For 18 mild preeclamptic patients the p-value was p=0.001 compared to their controls, while for the remaining nine with severe preeclampsia the expression became significant (p=0.001).

CONCLUSION

Our results suggest that the high KiSS-1 expression seen in preeclamptic patients is in accordance with its role as an inhibitor of trophoblast invasiveness and maintained until the end of gestation. On the other hand, aggressive therapeutic management and/or severity status of patients have a direct effect on placental REN expression levels, masking the natural high expression of this gene on preeclamptic placental tissue. Therefore it was not possible to establish a real concordant expression profile for KiSS-1 and REN genes.

Decorin is a novel VEGFR-2-binding antagonist for the human extravillous trophoblast

Extravillous trophoblasts (EVT) of the human placenta invade the uterine decidua and its arteries to ensure successful placentation. We previously identified two decidua-derived molecules, TGF-β and a TGF-β-binding proteoglycan decorin (DCN), as negative regulators of EVT proliferation, migration, and invasiveness and reported that DCN acts via multiple tyrosine kinase receptors [epidermal growth factor-receptor (EGF-R), IGF receptor-1 (IGFR1), and vascular endothelial growth factor 2 receptor (VEGFR-2)]. Because binding of DCN to VEGFR-2 has never been reported earlier, present study explored this binding, the approximate location of VEGFR-2-binding site in DCN, and its functional role in our human first trimester EVT cell line HTR-8/SVneo. Based on far-Western blotting and coimmunoprecipitation studies, we report that DCN binds both native (EVT expressed) and recombinant VEGFR-2 and that this binding is abrogated with a VEGFR-2 blocking antibody, indicating an overlap between the ligand-binding and the DCN-binding domains of VEGFR-2. We determined that (125)I-labeled VEGF-E (a VEGFR-2 specific ligand) binds EVT with a dissociation constant (K(d)) of 566 pM, and DCN displaced this binding with an inhibition constant (K(i)) of 3.93-5.78 nM, indicating a 7- to 10-fold lower affinity of DCN for VEGFR-2. DCN peptide fragments derived from the leucine rich repeat 5 domain that blocked DCN-VEGFR-2 interactions or VEGF-E binding in EVT cells also blocked VEGF-A- and VEGF-E-induced EVT cell proliferation and migration, indicative of functional VEGFR-2-binding sites of DCN. Finally, DCN inhibited VEGF-E-induced EVT migration by interfering with ERK1/2 activation. Our findings reveal a novel role of DCN as an antagonistic ligand for VEGFR-2, having implications for pathophysiology of preeclampsia, a trophoblast hypoinvasive disorder in pregnancy, and explain its antiangiogenic function.

Placental growth factor as short-term predicting biomarker in acute coronary syndrome patients with non-ST elevation myocardial infarction

OBJECTIVES

The relevance of placental growth factor was analyzed at the admission of patients with acute coronary syndrome (ACS) without ST elevation in prognosis of fatal outcome after 30 days.

METHODS

We collected blood samples from 102 ACS patients admitted to the coronary unit with acute chest pain manifesting within the last 12 hours.

RESULTS

In all 102 admitted patients, higher values of placental growth factor (PLGF; >13.2 ng/L, average value) indicated a higher risk of fatal outcome (hazard ratio [HR] 2.28, 95% confidence interval [CI] 1.21- 4.76, P = 0.0125). PLGF is an important independent prognostic marker (adjusted HR 2.35, 95% CI 1.98-4.61, P = 0.1338), and this was shown in a multiparameter model, which involved other statistically important markers of relative risk (age >65, gender, and estimated glomerular filtration rate [eGFR]).

CONCLUSION

PLGF levels measured at 12 hours of symptom onset and 30 days later may independently predict fatal outcome in patients with ACS without ST elevation.

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.

Nicotine restores endothelial dysfunction caused by excess sFlt1 and sEng in an in vitro model of preeclamptic vascular endothelium: a possible therapeutic role of nicotinic acetylcholine receptor (nAChR) agonists for preeclampsia

OBJECTIVE

In this study we tested the hypothesis that nicotine restores proangiogenic functions to endothelial cells pretreated with soluble fms-like tyrosine kinase 1 and/or soluble endoglin.

STUDY DESIGN

Wound healing assay and tube formation assay were performed using human umbilical vein endothelial cells treated with nicotine (10(-9) to 10(-6) M), and with various combinations of soluble fms-like tyrosine kinase 1 (100 ng/mL), soluble endoglin (100 ng/mL), and nicotine (10(-7) M). Enzyme-linked immunosorbent assay was performed to measure vascular endothelial growth factor, placental growth factor, and transforming growth factor-beta1 concentrations in the conditioned media treated with nicotine (10(-9) to 10(-6) M).

RESULTS

Nicotine significantly facilitated endothelial migration and tube formation. By contrast, soluble fms-like tyrosine kinase 1 and/or soluble endoglin suppressed these endothelial functions. Nicotine restored these soluble fms-like tyrosine kinase 1 and/or soluble endoglin-reduced endothelial functions. Placental growth factor, but not transforming growth factor-beta1, production was significantly stimulated by the presence of nicotine. Vascular endothelial growth factor was undetectable.

CONCLUSION

Our results suggest a possible mechanism for the protective effects of cigarette smoking against preeclampsia, thus proposing a therapeutic potential of nicotine or other nicotinic acetylcholine receptor agonists for preeclampsia.

Anti-tumor effects of a novel chimeric peptide on S180 and H22 xenografts bearing nude mice

In recent years, many endogenous peptides have been identified by screening combinatory phage display peptide library, which play important roles in the process of angiogenesis. A heptapeptide, ATWLPPR, binds specifically to NRP-1 and selectively inhibits VEGF165 binding to VEGFR-2. Another heptapeptide, NLLMAAS, blocks both Ang-1 and Ang-2 binding to Tie-2 in a dose-dependent manner. In the present study, we aimed to connect ATWLPPR (V1) with NLLMAAS (V2) via a flexible linker, Ala-Ala, to reconstruct a novel peptide ATWLPPRAANLLMAAS (V3). We firstly investigated the anti-tumor and anti-angiogenic effects of peptide V3 on sarcoma S180 and hepatoma H22 bearing BALB/c nude mice. Mice were continuously subcutaneously administrated with normal saline, V1 (320microg/kg/d), V2 (320microg/kg/d), V1+V2 (320microg/kg/d), and V3 (160, 320 and 480microg/kg/d), for 7 days. Treatment with peptide V3 could significantly reduce the tumor weight and volume. Pathological examination showed that the tumors treated with peptide V3 had a larger region of necrosis than that of peptide V1, V2, and V1+V2 at the same dose. A significant decrease of microvessel density (MVD) in a dose-dependent manner was observed in each group of peptide V3. The results of pathological examination on normal tissue, lung, heart, liver, spleen, kidney and white blood cells showed that peptide V3 might have no significant toxicity. In conclusion, our results demonstrated that peptide V3 could be more effective on inhibiting tumor growth and angiogenesis than that of V1, V2, and V1+V2. Peptide V3 could be considered as a novel chimeric peptide with potent anti-tumor activity.