Noncatalytic domain of uPA stimulates human extravillous trophoblast migration by using phospholipase C, phosphatidylinositol 3-kinase and mitogen-activated protein kinase

SERPINA5 may promote the development of preeclampsia by disruption of the uPA/uPAR pathway

Preeclampsia (PE) is the leading cause of maternal and fetal morbidity or mortality but lacks reliable methods for early diagnosis. In a previous study, serum SERPINA5 levels were higher in women with PE before the clinical manifestation of the disease. This study aimed to evaluate the efficacy of SERPINA5 in predicting PE and investigate its role in trophoblast cell biology. A multicenter, 2-stage observational case-control study was performed to develop and validate an early predictive PE model based on SERPINA5, maternal characteristics, and inflammatory factors. To further understand the relationship between SERPINA5 and PE, SERPINA5 was overexpressed or knocked down in extravillous trophoblast cells (EVT) and a pregnant rat model. After development and initial validation, a model that combined SERPINA5 and inflammatory factors had a high predictive ability for PE before 20 weeks gestation with an AUC of 0.90 (95% CI 0.83-0.96). It also demonstrated that SERPINA5 inhibited primary EVT cell invasion by disrupting the urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor (uPA/uPAR) pathway, in turn, is involved in the development of PE. In vivo experiments also proved that overexpression of SERPINA5 induced a PE-like syndrome (hypertension and proteinuria) in pregnant rats. Therefore, serum SERPINA5 is a promising early biomarker of PE, suggesting that it may be involved in placental development through its action on the uPA/uPAR system prior to the clinical manifestation of PE.

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.

Early pregnancy protein multiplex screening reflects circulating and urinary divergences associated with the development of preeclampsia

BACKGROUND

Preeclampsia, a pregnancy disorder characterized by hypertension and proteinuria, represents the leading cause of fetal and maternal morbidity and mortality in developing countries. The identification of novel and accurate biomarkers that are predictive of preeclampsia is necessary to improve the prognosis of patients with preeclampsia.

OBJECTIVE

To evaluate the preeclampsia predictive value of 34 angiogenic-related proteins.

METHODS

We performed a nested cohort case-control study of pregnant women. The profile of the 34 proteins was evaluated at 12, 16, and 20 gestational weeks (GWs), using urine/plasma from 16 women who developed preeclampsia and 20 normotensive pregnant controls by Bio-Plex Pro^TM Human Cancer Biomarker Panels 1 and 2.

RESULTS

The urine concentration of soluble epidermal growth factor receptor (sEGFR), hepatocyte growth factor (HGF), angiopoietin-2 (ANG-2), endoglin (ENG), soluble fas ligand (sFASL), interleukin 6 (IL-6), placental growth factor (PLGF), and vascular endothelial growth factor A (VEGF-A) at 12 GW, prolactin (PRL), ANG-2, transforming growth factor alpha (TGF-α), and VEGF-A at 16 GW, and soluble IL-6 receptor alpha (sIL-6Rα), ANG-2 and sFASL at 20 GW, were different between groups (p < 0.05). The concentration cut-off values calculated in this study for the mentioned proteins, predicted an increased risk to developing preeclampsia in a range of 3.8-29.8 times in the study population.

CONCLUSION

The proteins sEGFR, HGF, ANG-2, sFASL, IL-6, PLGF, VEGF-A, PRL, TGF-α FGF-b, sHER2/Neu sIL-6Rα, ENG, uPA, and insulin-like growth factor binding protein 1 (IGFBP-1), were predictive of the development of preeclampsia and their use as markers for this disease should be considered.

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.

Immunological modes of pregnancy loss: inflammation, immune effectors, and stress

Inflammatory immune response plays a key role in reproductive failures such as multiple implantation failures (MIF), early pregnancy loss, and recurrent pregnancy losses (RPL). Cellular immune responses particularly mediated by natural killer (NK), and T cells are often dysregulated in these conditions. Excessive or inappropriate recruitment of peripheral blood NK cells to the uterus may lead to cytotoxic environment in utero, in which proliferation and differentiation of trophoblast is hampered. In addition, inadequate angiogenesis by uterine NK cells often leads to abnormal vascular development and blood flow patterns, which, in turn, leads to increased oxidative stress or ischemic changes in the invading trophoblast. T-cell abnormalities with increased Th1 and Th17 immunity, and decreased Th2 and T regulatory immune responses may play important roles in RPL and MIF. A possible role of stress in inflammatory immune response is also reviewed.

Review: the ADAM metalloproteinases - novel regulators of trophoblast invasion?

During pregnancy, the extravillous trophoblast (EVT) invades the maternal decidua and remodels spiral arteries reaching as far as the inner third of the myometrium. This process is mandatory to a successful pregnancy since EVTs regulate spiral artery remodeling to achieve maximal vasodilation and thus an adequate nutrient supply to the embryo or communicate with maternal leukocyte populations to guarantee acceptance of the allogeneic conceptus. To achieve this, EVTs undergo a remarkable and unique differentiation process, which yields different phenotypes such as proliferative cell column trophoblasts or growth-arrested, invasive interstitial or endovascular cytotrophoblasts. Matrix metalloproteinases have long been seen as imperative to trophoblast invasion because of their ability to degrade extracellular matrix and therefore allow cellular movement in foreign tissues. However, global gene expression analysis reveals that EVTs also express various members of distintegrin and metalloproteinases (ADAMs). These proteases are associated with the process of proteolytic shedding and activation of surface proteins including growth factors, cytokines, receptors and their ligands rather than extracellular matrix breakdown. While ADAM12 has been associated with chromosomal abnormalities as well as preeclampsia or intrauterine fetal growth restriction, the function of ADAMs in trophoblasts remains elusive. In this article, we review the diverse invasive trophoblast phenotypes, EVT-associated protease systems and related open questions. In addition, we examine recent information about relevant ADAM members and their putative implications for EVT biology.

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

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

Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The role of interleukin-1β in human trophoblast motility

The pleiotropic cytokine interleukin-1β (IL-1β) can promote physiological cell migration, as well as cancer cell invasion and metastasis. Its role in human trophoblast invasion, however, has not been satisfactorily answered since direct, indirect as well as no effects on trophoblast motility have been published. Therefore, the role of IL-1β has been re-evaluated by exclusively using human primary trophoblast model systems. Immunofluorescence of first trimester placentae indicated IL-1 receptor 1 (IL-1R1) protein expression in first trimester villous cytotrophoblasts (vCTB) and extravillous trophoblasts (EVT). The latter expressed higher mRNA levels of the receptor as shown by comparative gene chip data of vCTB and EVT. Similarly, Western blot analyses and immunofluorescence revealed a time- and differentiation-dependent increase of IL-1R1 in primary EVT seeded on fibronectin. IL-1β dose-dependently elevated migration of isolated first trimester EVT through fibronectin-coated transwells, which was inhibited in the presence of IL-1R antagonist (IL-1Ra), whereas proliferation of these cells was not affected. Similarly, the interleukin did not alter proliferation of vCTB and cell column trophoblasts in floating villi of early pregnancy, but promoted migration in villous explant cultures seeded on collagen I. Western blot analyses of supernatants of primary EVT and first trimester villous explant cultures revealed IL-1β induced secretion of urokinase plasminogen activator (uPA), plasminogen activator inhibitor (PAI)-1 and PAI-2, which was diminished upon combined IL-1β/IL-1Ra treatment. In conclusion, these data suggest that IL-1β directly promotes trophoblast motility of first trimester EVT involving the uPA/PAI system.

Remodelling at the maternal–fetal interface: relevance to human pregnancy disorders

In human pregnancy, successful placentation and remodelling of the uterine vasculature require the integration of a number of stages, which are crucial for a healthy pregnancy. As the demands of the developing fetus for nutrients and oxygen increase, the capacity of the maternal blood vessels to supply this must be altered radically, with deficiencies in this process implicated in a number of dangerous pregnancy complications. The complex signalling networks that regulate these tightly co-ordinated events are becoming clearer as more studies of early pregnancy are performed. It is the aim of this review to draw together our knowledge of events that occur to facilitate a successful pregnancy ranging from the preparation for implantation, through the invasion and differentiation of the trophoblast and the regulation of these processes by other cells within the decidual environment, to the active role that the trophoblast and maternal immune cells play in facilitating the remodelling of the uterine spiral arteries. The events involved in a healthy pregnancy will then be compared to aberrant placentation and remodelling, which are characteristics of many pregnancy disorders, and recent advances in detection of abnormal placental development will also be discussed.

Critical growth factors and signalling pathways controlling human trophoblast invasion

Invasion of placental trophoblasts into uterine tissue and vessels is an essential process of human pregnancy and fetal development. Due to their remarkable plasticity invasive trophoblasts fulfil numerous functions, i.e. anchorage of the placenta, secretion of hormones, modulation of decidual angiogenesis/lymphangiogenesis and remodelling of maternal spiral arteries. The latter is required to increase blood flow to the placenta, thereby ensuring appropriate transfer of nutrients and oxygen to the developing fetus. Since failures in vascular changes of the placental bed are associated with pregnancy diseases such as preeclampsia or intrauterine growth restriction, basic research in this particular field focuses on molecular mechanisms controlling trophoblast invasion under physiological and pathological conditions. Throughout the years, an increasing number of growth factors, cytokines and angiogenic molecules controlling trophoblast motility have been identified. These factors are secreted from numerous cells such as trophoblast, maternal epithelial and stromal cells, as well as uterine NK cells and macrophages, suggesting that a complex network of cell types, mediators and signalling pathways regulates trophoblast invasiveness. Whereas essential features of the invasive trophoblast such as expression of critical proteases and adhesion molecules have been well characterised, the interplay between different cell types and growth factors and the cross-talk between distinct signalling cascades remain largely elusive. Similarly, key-regulatory transcription factors committing and differentiating invasive trophoblasts are mostly unknown. This review will summarise our current understanding of growth factors and signal transduction pathways regulating human trophoblast invasion/migration, as well as give insights into novel mechanisms involved in the particular differentiation process.

Function-specific intracellular signaling pathways downstream of heparin-binding EGF-like growth factor utilized by human trophoblasts

Heparin-binding EGF-like growth factor (HBEGF) is expressed by trophoblast cells throughout gestation. First-trimester cytotrophoblast cells are protected from hypoxia-induced apoptosis because of the accumulation of HBEGF through a posttranscriptional autocrine mechanism. Exogenous application of HBEGF is cytoprotective in a hypoxia/reoxygenation (H/R) injury model and initiates trophoblast extravillous differentiation to an invasive phenotype. The downstream signaling pathways induced by HBEGF that mediate these various cellular activities were identified using two human first-trimester cytotrophoblast cell lines, HTR-8/SVneo and SW.71, with similar results. Recombinant HBEGF (1 nM) induced transient phosphorylation of MAPK3/1 (ERK), MAPK14 (p38), and AKT within 15 min and JNK after 1-2 h. To determine which downstream pathways regulate the various functions of HBEGF, cells were treated with specific inhibitors of the ERK upstream regulator MEK (U0126), the AKT upstream regulator phosphoinositide-3 (PI3)-kinase (LY294002), MAPK14 (SB203580), and JNK (SP600125), as well as with inactive structural analogues. Only SB203580 specifically prevented HBEGF-mediated rescue during H/R, while each inhibitor attenuated HBEGF-stimulated cell migration. Accumulation of HBEGF at reduced oxygen was blocked only by a combination of U0126, SB203580, and SP600125. We conclude that HBEGF advances trophoblast extravillous differentiation through coordinate activation of PI3 kinase, ERK, MAPK14, and JNK, while only MAPK14 is required for its antiapoptotic activity. Additionally, hypoxia induces an autocrine increase in HBEGF protein levels through MAPK14, JNK or ERK. These experiments reveal a complexity of the intracellular signaling circuitry that regulates trophoblast functions critical for implantation and placentation.

Beyond oxygen: complex regulation and activity of hypoxia inducible factors in pregnancy

In the first trimester the extravillous cytotrophoblast cells occlude the uterine spiral arterioles creating a low oxygen environment early in pregnancy, which is essential for pregnancy success. Paradoxically, shallow trophoblast invasion and defective vascular remodelling of the uterine spiral arteries in the first trimester may result in impaired placental perfusion and chronic placental ischemia and hypoxia later in gestation leading to adverse pregnancy outcomes. The hypoxia inducible factors (HIFs) are key mediators of the response to low oxygen. We aimed to elucidate mechanisms of regulation of HIFs and the role these may play in the control of placental differentiation, growth and function in both normal and pathological pregnancies. The Pubmed database was consulted for identification of the most relevant published articles. Search terms used were oxygen, placenta, trophoblast, pregnancy, HIF and hypoxia. The HIFs are able to function throughout all aspects of normal and abnormal placental differentiation, growth and function; during the first trimester (physiologically low oxygen), during mid-late gestation (where there is adequate supply of blood and oxygen to the placenta) and in pathological pregnancies complicated by placental hypoxia/ischemia. During normal pregnancy HIFs may respond to complex alterations in oxygen, hormones, cytokines and growth factors to regulate placental invasion, differentiation, transport and vascularization. In the ever-changing environment created during pregnancy, the HIFs appear to act as key mediators of placental development and function and thereby are likely to be important contributors to both normal and adverse pregnancy outcomes.

Expression, regulation and functional characterization of matrix metalloproteinase-3 of human trophoblast

MMP-3 has been detected in human placenta and reduced expression of the enzyme was observed in invasive trophoblasts of patients with severe preeclampsia. However, detailed expression pattern, regulation and biological properties of the placental protease have not been elucidated so far. RT-PCR analyses, Western blotting and enzyme activity assays revealed that pro- and active form of MMP-3 were predominantly expressed in purified first trimester villous trophoblasts, in invasive cytotrophoblasts of differentiating explant cultures and in trophoblastic SGHPL-4 cells. Accordingly, immunofluorescene of first trimester placental tissues detected MMP-3 mainly in villous and extravillous cytotrophoblasts. IL-1beta, an inducer of MMP-3 in decidual cells, increased secretion and activity of the protease in trophoblast supernatants in a dose- and time-dependent manner. IL-1beta-stimulated production of the enzyme was suppressed in the presence of inhibitors of MAPK and AKT signalling. Similar to recombinant MMP-3, MMP-3 in supernatants of IL-1beta-stimulated decidual stromal or SGHPL-4 cells degraded IGFBP-1 in vitro resulting in the appearance of cleavage products at approximately 25, 22, 17, 14 and 11kD. However, cleavage assays using recombinant MMP-2 suggested that the gelatinase may contribute to IGFBP-1 degradation in trophoblast supernatants. Despite its effects on MMP-3 expression IL-1beta failed to significantly alter invasion of SGHPL-4 cells through Matrigel-coated transwells. In conclusion, the data suggest that invasive trophoblast cell models secrete bioactive MMP-3. Inducible expression of the protease involves MAPK and AKT signalling. In addition to the decidua, MMP-3 of trophoblasts may contribute to the regulation of the IGF system by degrading IGFBP-1.

Decorin-mediated inhibition of proliferation and migration of the human trophoblast via different tyrosine kinase receptors

Decorin (DCN), a decidua-derived TGFbeta-binding proteoglycan, negatively regulates proliferation, migration, and invasiveness of human extravillous trophoblast (EVT) cells in a TGFbeta-independent manner. The present study examined underlying mechanisms, in particular possible roles of epidermal growth factor receptor (EGFR), IGF receptor (IGFR)-I, and vascular endothelial growth factor receptor (VEGFR)-2. EVT cell sprouting from first-trimester chorionic villus explants in the presence or absence of TGFbeta-neutralizing antibody was inhibited with DCN, suggesting its negative regulatory role in situ. Inhibition of migration of the human EVT cell line HTR-8/SVneo in transwells undercoated with fibronectin was stronger when cells were briefly preincubated with DCN at 4 C (known to retard dissociation of receptor-ligand complex) than at 37 C, suggesting possible DCN action by cell membrane binding. Pretreatment of cells with an IGFR-I blocking agent, but not two EGFR blocking agents or a VEGFR blocking agent, significantly abrogated migration inhibitory effects of DCN, suggesting the involvement of IGFR-I but not EGFR or VEGFR in migration inhibition by DCN. On the other hand, pretreatment with either of the EGFR blocking agents, or the VEGFR blocking agent but not the IGFR-I blocking agent, blocked proliferation inhibitory effects of DCN, indicating the roles of EGFR and VEGFR, but not IGFR-I in antiproliferative action of DCN. EVT cells expressed EGFR, IGFR-I, and VEGFR-2. IGFR-I and VEGF-R2 were phosphorylated in the presence of their natural ligands as well as DCN, and these events were blocked by pretreatment with respective receptor blocking agents indicating DCN-mediated activation of these receptors. In conclusion, DCN effects on EVT cells are mediated selectively by multiple tyrosine kinase receptors.

Expression of extracellular signal-regulated kinase1/2 and p38 mitogen-activated protein kinase in the invasive trophoblasts at the human placental bed

BACKGROUND

Mitogen-activated protein kinases (MAP kinases) participate in signal transduction pathways that control embryogenesis, cell differentiation, cell proliferation and cell death. The roles of extracellular signal-regulated kinase1/2 (ERK1/2) and p38 MAP kinase in the differentiation and invasion of human trophoblasts have been studied. However, the in vivo expression and activation of ERK1/2 and p38 at the placental bed have not been elucidated.

METHODS

The study group consisted of placental bed biopsy tissues obtained from the pregnancies without preeclampsia (n=24) and with preeclampsia (n=8) between 31 and 40 weeks of gestation. We evaluated the expressions and phosphorylations of ERK1/2 and p38 MAP kinase in the invasive trophoblasts in the placental bed tissues using immunohistochemistry.

RESULTS

p38 and phospho-p38 MAP kinase were not detected in invasive trophoblasts in cases or controls. ERK1/2 and phospho-ERK1/2 were positive in invasive trophoblasts albeit with variable staining. Phosphorylation of ERK1/2 was significantly less frequent in invasive trophoblasts in placental bed biopsies from women with preeclampsia compared with normotensive controls.

CONCLUSION

These findings suggest that preeclampsia is associated with decreased activation of ERK1/2 in invasive trophoblasts in vivo.

Prostaglandin E2-mediated migration of human trophoblast requires RAC1 and CDC42

The invasion of maternal decidua and uterine spiral arteries by a trophoblast subpopulation called extravillous trophoblast (EVT) is essential for the establishment of a normal placenta and an adequate blood flow toward the fetus. Derangements in these processes underlie pregnancy-related diseases like preeclampsia and intrauterine growth restriction. Many growth factors, growth factor binding proteins, and extracellular matrix components can positively or negatively regulate the proliferation, migration, and/or invasiveness of these EVT cells. RHO GTPases, including RHOA, RAC1, and CDC42, are ubiquitous proteins that control cytoskeletal changes by forming stress fibers and projecting lamellipodia and filopodia during cellular migration. We had previously shown that prostaglandin (PG) E(2) produced in abundance by the decidua promotes the migration of first-trimester human EVTs by increasing the intracellular concentration of calcium and activating calpain. Using our well-characterized immortalized EVT cell line, HTR-8/SVneo, as well as villus explants from first-trimester placentae, this study examined the role of RHO GTPases RAC1 and CDC42 in PGE(2)-mediated migratory responses of these cells. Though a RAC1 inhibitor, NSC23766 as well as RAC1 knockdown by siRNA decreased the migration of HTR-8/SVneo cells in a Transwell migration assay, this inhibition could not be restored by PGE(2) or 17-phenyl trinor PGE(2) (PGE receptor PTGER1 agonist) or PGE(1) Alcohol (PGE receptor PTGER4 agonist). Similar results were noted for EVT cell spreading in villus explants. Furthermore, CDC42 silencing using siRNA inhibited PGE(2)-induced migration of HTR-8/SVneo cells. Finally, the treatment of EVT cells with PGE(2), PTGER1 agonist, or PTGER4 agonist activated RAC1 and CDC42 at 10 min, suggesting that RAC1 and CDC42 play an essential role in PGE(2)-mediated migration of human EVTs.

Urokinase-type plasminogen activator stimulation of monocyte matrix metalloproteinase-1 production is mediated by plasmin-dependent signaling through annexin A2 and inhibited by inactive plasmin

Chronic inflammatory diseases are associated with connective tissue turnover that involves a series of proteases, which include the plasminogen activation system and the family of matrix metalloproteinases (MMPs). Urokinase-type plasminogen activator (uPA) and plasmin, in addition to their role in fibrinolysis and activation of pro-MMPs, have been shown to transduce intracellular signals through specific receptors. The potential for uPA and plasmin to also contribute to connective tissue turnover by directly regulating MMP production was examined in human monocytes. Both catalytically active high m.w. uPA, which binds to the uPAR, and low m.w. uPA, which does not, significantly enhanced MMP-1 synthesis by activated human monocytes. In contrast, the N-terminal fragment of uPA, which binds to uPAR, but lacks the catalytic site, failed to induce MMP-1 production, indicating that uPA-stimulated MMP-1 synthesis was plasmin dependent. Endogenous plasmin generated by the action of uPA or exogenous plasmin increased MMP-1 synthesis by signaling through annexin A2, as demonstrated by inhibition of MMP-1 production with Abs against annexin A2 and S100A10, a dimeric protein associated with annexin A2. Interaction of plasmin with annexin A2 resulted in the stimulation of ERK1/2 and p38 MAPK, cyclooxygenase-2, and PGE(2), leading to increased MMP-1 production. Furthermore, binding of inactive plasmin to annexin A2 inhibited plasmin induction of MMP-1, suggesting that inactive plasmin may be useful in suppressing inflammation.

The pathology of gestational trophoblastic disease: recent advances

When inundated with numerous specimens of products of conception as the consequence of miscarriage, it is all too easy for histopathologists to forget that the biology of trophoblast and the events of early placental implantation continue to fascinate because of the inherently invasive properties of the non-villous (extravillous) trophoblast. However, unlike the invasion of a malignant tumour, the invasion of trophoblast is controlled. The failure of adequate conversion of maternal uteroplacental arteries is a major pathogenetic phenomenon of important disorders of pregnancy including pre-eclampsia. However, it is in the field of gestational trophoblastic disease that diagnostic acumen is most called for. There are several problematic areas that give rise to diagnostic error; e.g., the diagnosis of early complete mole as partial mole, the over-diagnosis of hydatidiform mole in tubal pregnancy and the diagnosis of placental site non-villous trophoblast as placental site trophoblastic tumour or choriocarcinoma, particularly if associated with atypia, as frequently observed in complete mole. The chorionic villi of early diploid complete mole show characteristic features of villous profile, stromal mucin and stromal nuclear debris. The distinction between complete mole and triploid partial mole can be facilitated by ploidy analysis and immunohistochemistry for the product of the paternally imprinted, maternally expressed gene, p57kip2. Persistent trophoblastic disease (PTD) is a clinical not a histopathological diagnosis and the role of the histopathologist once a diagnosis of PTD has been made is limited. Invasive mole and choriocarcinoma are encompassed by PTD. Tumours of the non-villous trophoblast are placental site trophoblastic tumour and the more recently recognised epithelioid trophoblastic tumour. The role of immunohistochemistry in the elucidation of trophoblastic lesions is discussed pragmatically.

Preeclampsia: new insights

PURPOSE OF REVIEW

Preeclampsia is a disorder of gestation characterized by hypertension and proteinuria and can be complicated by eclamptic seizures. This review describes recent advances in the role of the renin-angiotensin system and angiogenic and anti-angiogenic factors of placental origin in its pathogenesis.

RECENT FINDINGS

Deficient uteroplacental perfusion has been recognized to be a feature in all preeclampsia syndromes. Increased renin expression observed in humans and animal models supports the concept that activation of the decidual renin-angiotensin system may mediate the pathogenesis of preeclampsia. Novel angiotensin II-related biomolecular mechanisms, angiotensin II type 1-B2 receptor heterodimerization and autoantibody against angiotensin II type 1 have recently been described in preeclampsia. New evidence suggests that vascular endothelial growth factor and its receptors, antagonists, and reduced placental growth factor may play a role in the development of proteinuria and other renal injury-mediated manifestations in preeclampsia.

SUMMARY

Vascular maladaptation, with increased vasomotor tone, endothelial dysfunction, increased sensitivity to angiotensin II and norepinephrine, and multiorgan dysfunction seen in preeclampsia, may be explained by angiotensin II-mediated mechanisms. Future investigations need to define the mechanism of activation of the decidual renin-angiotensin system and the release of placental factors in the pathogenesis of preeclampsia.

Membrane-bound peptidases regulate human extravillous trophoblast invasion

During human placentation, the extravillous trophoblast (EVT) invades maternal decidua and spiral arteries. However, the precise regulatory mechanisms by which EVT invasion is induced toward maternal arteries or limited within the uterus have not been well characterized. Recently, we found that dipeptidyl peptidase IV, a membrane-bound cell surface peptidase that can degrade chemokines, including RANTES, was expressed on EVT that had already ceased invasion. Another cell surface peptidase, carboxypeptidase-M, was also detected on EVT including the endovascular trophoblast in the maternal arteries. The inhibition of these peptidases increased cell invasion of choriocarcinoma-derived JEG-3 cells. On the other hand, CCR-1, a chemokine receptor for RANTES, was specifically expressed on EVT that migrated toward maternal arteries, while RANTES enhanced invasion of EVT that were isolated from primary villous explant culture. Platelets, which secrete RANTES and other chemokines, were detected among the endovascular trophoblast, and platelets were shown to enhance invasion of cultured EVT. Furthermore, a novel membrane-bound cell surface peptidase, laeverin, was found to be specifically expressed on EVT at deep sites in the maternal decidua. These findings suggest that membrane-bound peptidases regulate EVT invasion in cooperation with a chemokine system during early human placentation.

Decidual NK cells alter in vitro first trimester extravillous cytotrophoblast migration: a role for IFN-gamma

Abnormal placentation results in either inadequate (consequences: recurrent miscarriage, intrauterine growth restriction, and preeclampsia) or overzealous (consequences: placenta accreta, increta, and percreta) placentation. NK cells dominate in first trimester decidua and probably control extravillous cytotrophoblast (EVT) invasion. We examined this interaction in a novel way, using NK cells and villous explants from concordant first trimester pregnancies cocultured using a new collagen (two-dimensional) model of placentation. Decidual NK (dNK) cells exerted contact-independent inhibition of normal cytotrophoblast migration, associated with changes in the cytotrophoblast expression of metalloproteases-2 and -9, and plasminogen activator inhibitor-1. dNK cells did not affect EVT proliferation and apoptosis, and cell column formation. dNK cell effects were partially reversed by neutralizing Abs against IFN-gamma. We provide ex vivo human evidence of a direct role for dNK in modulating EVT differentiation as they form columns and then migrate from anchoring villi.

Candidate-gene association study of mothers with pre-eclampsia, and their infants, analyzing 775 SNPs in 190 genes

Pre-eclampsia (PE) affects 5-7% of pregnancies in the US, and is a leading cause of maternal death and perinatal morbidity and mortality worldwide. To identify genes with a role in PE, we conducted a large-scale association study evaluating 775 SNPs in 190 candidate genes selected for a potential role in obstetrical complications. SNP discovery was performed by DNA sequencing, and genotyping was carried out in a high-throughput facility using the MassARRAY(TM) System. Women with PE (n = 394) and their offspring (n = 324) were compared with control women (n = 602) and their offspring (n = 631) from the same hospital-based population. Haplotypes were estimated for each gene using the EM algorithm, and empirical p values were obtained for a logistic regression-based score test, adjusted for significant covariates. An interaction model between maternal and offspring genotypes was also evaluated. The most significant findings for association with PE were COL1A1 (p = 0.0011) and IL1A (p = 0.0014) for the maternal genotype, and PLAUR (p = 0.0008) for the offspring genotype. Common candidate genes for PE, including MTHFR and NOS3, were not significantly associated with PE. For the interaction model, SNPs within IGF1 (p = 0.0035) and IL4R (p = 0.0036) gave the most significant results. This study is one of the most comprehensive genetic association studies of PE to date, including an evaluation of offspring genotypes that have rarely been considered in previous studies. Although we did not identify statistically significant evidence of association for any of the candidate loci evaluated here after adjusting for multiple testing using the false discovery rate, additional compelling evidence exists, including multiple SNPs with nominally significant p values in COL1A1 and the IL1A region, and previous reports of association for IL1A, to support continued interest in these genes as candidates for PE. Identification of the genetic regulators of PE may have broader implications, since women with PE are at increased risk of death from cardiovascular diseases later in life.

Genomewide oligonucleotide microarray analysis on placentae of pre-eclamptic pregnancies

OBJECTIVE

Human placentae from normal and pre-eclamptic pregnancies were evaluated for possible changes in gene expression by microarray analysis to uncover new clues for the research of the etiology of pre-eclampsia.

METHODS

Placentae from five normal pregnancies and five pregnancies complicated by pre-eclampsia were collected. mRNA levels of five pre-eclamptic placentae were examined using genome-wide 70-mer oligonucleotide microarrays (CapitalBio, Beijing, China) in comparison with the pooled control consisting of total RNA from five normotensive placentae.

RESULTS

Ninety-six genes were found consistently down- or up-regulated in at least four pre-eclamptic samples. Most of them were related to an imbalance of reactive oxygen metabolites in placenta, abnormal trophoblast invasion, disorders of lipoprotein metabolism and signal transduction, or some that have been reported to have close correlation to the pathology of pre-eclampsia. The microarray data were also confirmed by the measurement of real-time PCR.

CONCLUSION

DNA microarray is a high throughput and time-saving method to monitor altered gene expression. The results could provide interesting clues to the etiology of pre-eclampsia and lead to further studies in a more targeted fashion.

TNFalpha-mediated induction of PAI-1 restricts invasion of HTR-8/SVneo trophoblast cells

The pro-inflammatory cytokine TNFalpha has numerous effects on placental trophoblasts. Here, we investigated the effects of the cytokine on gene expression and function of the extravillous trophoblast cell line HTR-8/SVneo. Wound healing and Matrigel invasion assays demonstrate that TNFalpha impairs motility and invasiveness. In contrast, counting of cumulative cell numbers and FACS analyses revealed that the cytokine did neither affect proliferation nor distribution of cell cycle phases. Immunocytochemistry of the cytokeratin 18 neo-epitope suggests that TNFalpha did not induce apoptosis in HTR-8/SVneo cells. Gelatine zymography and enzyme activity assays of supernatants of TNFalpha-treated cells demonstrate elevation of the pro- and active form of MMP-9 suggesting that increased expression of the protease cannot overcome the TNFalpha-inhibitory effect on cell invasion. Semi-quantitative RT-PCR analyses suggest that the cytokine may not alter mRNA levels of uPA and tPA. However, elevated expression of PAI-1 was detected by RT-PCR, as well as by Northern and Western blot analyses. Supplementation of PAI-1-blocking antibodies restored invasion of TNF-alpha-incubated HTR-8/SVneo cells through Matrigel-coated transwells. In addition, immunocytochemistry revealed nuclear accumulation of the p65 subunit of NFkappaB in the presence of the cytokine. EMSA indicated TNFalpha-induced binding of the inflammatory transcription factor to an NFkappaB consensus sequence and to the NFkappaB recognition site located in the PAI-1 promoter. The data suggest that TNFalpha restricts trophoblast invasion mainly by increasing the expression of PAI-1. Induction of the inhibitor may involve TNFalpha-stimulated activation of NFkappaB.

Histamine enhances cytotrophoblast invasion by inducing intracellular calcium transients through the histamine type-1 receptor

Blastocyst implantation and placentation require molecular and cellular interactions between the uterine endometrium and blastocyst trophectoderm. Previous studies showed that histamine produced in the mouse uterine luminal epithelium interacts with trophoblast histamine type-2 receptors (H2) to initiate blastocyst implantation. However, it is unknown whether similar histamine activity is operative in humans. Using a human cell line (HTR-8/SVneo) derived from first-trimester cytotrophoblasts that expresses both histamine type-1 receptor (H1) and H2, we found that histamine promotes cytotrophoblast invasiveness specifically through activation of H1. Stimulation of H1 in human cytotrophoblasts by histamine induced intracellular Ca2+ (Ca(2+)i) transients by activating phospholipase C and the inositol trisphosphate pathway. The enhanced invasion induced by histamine was blocked by pretreatment with H1 antagonist or by chelation of Ca(2+)i. These findings suggest possible differences between rodents and humans in histamine signaling to the trophoblast.

Signalling pathways regulating the invasive differentiation of human trophoblasts: a review

The invasive differentiation pathway of trophoblasts is an indispensable physiological process of early human placental development. Formation of anchoring villi, proliferation of cell columns and invasion of extravillous cytotrophoblasts into maternal decidual stroma and vessels induce vascular changes ensuring an adequate blood supply to the growing fetus. Extravillous trophoblast differentiation is regulated by numerous growth factors as well as by extracellular matrix proteins and adhesion molecules expressed at the fetal-maternal interface. These regulatory molecules control cell invasion by modulating activities of matrix-degrading protease systems and ECM adhesion. The differentiation process involves numerous signalling cascades/proteins such as the GTPases RhoA, the protein kinases ROCK, ERK1, ERK2, FAK, PI3K, Akt/protein kinase B and mTOR as well as TGF-beta-dependent SMAD factors. While an increasing number of signalling pathways regulating trophoblast differentiation are being unravelled, downstream effectors such as executing transcription factors remain largely elusive. Here, we summarise our current knowledge on signal transduction cascades regulating invasive trophoblast differentiation. We will focus on cell model systems which are used to study the particular differentiation process and discuss signalling pathways which regulate trophoblast proliferation and motility.

Regulation of human extravillous trophoblast function by membrane-bound peptidases

During human placentation, the invasion of extravillous trophoblasts (EVTs) into maternal decidual tissues, especially toward maternal spiral arteries, is considered an essential process for subsequent normal fetal development. However, the precise regulatory mechanisms to induce EVT invasion toward arteries and/or to protect EVTs from further invasion have not been well understood. Recently, we found that two cell surface peptidases, dipeptidyl peptidase IV (DPPIV) and carboxypeptidase-M (CP-M,) are differentially expressed on EVTs. DPPIV expression was mainly observed on EVTs that had already ceased invasion. CP-M was detected on migrating EVTs including endovascular trophoblasts in the maternal arteries. The enzymatic inhibition of these peptidases affected the invasive property of choriocarcinoma-derived cell lines, BeWo and JEG3 cells. In addition, a chemokine, RANTES, that is one of the substrates for DPPIV, enhanced invasion of EVTs isolated from primary villous explant culture and its receptor, CCR1, was specifically expressed on migrating EVTs toward maternal arteries. Furthermore, a novel membrane-bound cell surface peptidase, named laeverin, was found to be specifically expressed on EVTs that had almost ceased invasion. These findings suggest that membrane-bound peptidases are important factors regulating EVT invasion during early placentation in humans.

Inhibition of Trophoblast Cell Invasion by TGFB1, 2, and 3 Is Associated with a Decrease in Active Proteases1

Invasion of extravillous trophoblast cells into the uterus in human pregnancy is tightly regulated. The transforming growth factor-beta (TGFB) family has been suggested to play a role in controlling this process. We hypothesized that TGFB1, 2, and 3 would inhibit the invasive capacity of extravillous trophoblast cells. We also studied trophoblast apoptosis and proliferation and secreted protease levels as potential mechanisms by which these cytokines may act. Inhibition of endogenous TGFB1, 2, and 3 with neutralizing antibodies increased the invasive capacity of extravillous trophoblast cells derived from placental explants. Similarly, addition of exogenous TGFB1, 2, and 3 inhibited the invasive capacity of these cells in a dose-dependent manner. Proliferation of trophoblast in the placental explants did not alter in response to any of the cytokines tested. Apoptosis of villous and extravillous trophoblast did not alter in response to TGFB1, 2, and 3. There was a reduction in secreted levels of matrix metalloproteinase (MMP) 9 and urokinase plasminogen activator in response to all three cytokines. MMP2 and tissue inhibitor of metalloproteinase 1 and 3 levels were not altered. These results suggest that TGFB1, 2, and 3 inhibit trophoblast invasion by a mechanism dependent on reduced protease activity.

EP1 receptor-mediated migration of the first trimester human extravillous trophoblast: the role of intracellular calcium and calpain

CONTEXT

The root cause of preeclampsia in the human lies in the placenta, where a subpopulation of cytotrophoblast cells called extravillous trophoblasts (EVT), known to be involved in the invasion of the uterine endometrium and utero-placental arteries, become less invasive, resulting in poor perfusion of maternal blood into placenta.

OBJECTIVES

Because EVT migrate into the prostaglandin (PG) E2-rich decidua, we tested the roles of PGE2 and PGE2-mediated signaling in EVT migration, using our well-characterized EVT line HTR-8/Svneo as well as first trimester villus explants in culture.

DESIGN

mRNA expression of different PGE2 receptors (EPs) in HTR-8/Svneo cells was studied using RT-PCR. To characterize the functional significance of EP receptors in EVT, different EP receptor agonists and antagonists were used in our migration assay systems and in the measurements of intracellular concentration of Ca2+ ([Ca2+]i) and calpain activity.

RESULTS

Exogenous PGE2 stimulated EVT migration both in vitro and in the villus explant cultures. Although EVT expressed mRNA for all EP receptors (EP 1-4), a functional predominance of EP1 and EP4 was demonstrated in migration assays using specific EP agonists and antagonists. EP1-receptor-mediated signaling events such as activation of phospholipase C and elevation of cytosolic free [Ca2+]i were confirmed by the following findings: 1) exogenous PGE2 or an EP1 agonist, but not an EP4 agonist, increased [Ca2+]i, which could be blocked with an EP1 antagonist as well as BAPTA and thapsigargin; 2) phospholipase C inhibitor U73122, BAPTA, and thapsigargin inhibited PGE2-mediated migratory response of EVT; and 3) PGE2-mediated EVT migration was shown to be dependent on a class of Ca2+-dependent proteases called calpains, known to be involved in cell detachment from substratum during migratory responses. The presence of PGE2 stimulated calpain activity, whereas two calpain inhibitors, calpastatin and N-Ac-Leu-Leu-methioninal (ALLM), blocked EVT migration.

CONCLUSION

PGE2 stimulates EVT migration by signaling through EP1 receptors, increasing [Ca2+]i, and activating calpain.

New regulatory mechanisms for human extravillous trophoblast invasion

Human extravillous trophoblasts (EVT) invade maternal deciduas and reconstructed maternal spiral arteries during early placentation. However, the precise regulatory mechanisms to induce EVT invasion toward arteries and/or to protect EVT from further invasion have not been well understood. Recently, it was found that EVT that had already ceased their invasion, specifically expressed cluster of differentiation (CD9) and dipeptidyl peptidase IV (DPPIV) on their cell surface. In addition, EVT migrating to maternal spiral arteries expressed CC chemokine receptor type-1 (CCR-1), which is a chemokine receptor for regulated on activation normal T cell expressed and secreted (RANTES) and so on. CD9 is associated with integrin molecules on the cell surface and is considered to modulate integrin function. In contrast, DPPIV is a cell surface peptidase that can metabolize RANTES at extracellular sites before its accessing to the chemokine receptors. In vitro functional assay showed that CD9, DPPIV and RANTES are involved in the regulation for EVT invasion. From these findings, it can be proposed that CD9 and DPPIV, including chemokines, are new regulatory factors for human extravillous trophoblasts. (Reprod Med Biol 2005; 4: 189-195).

Blastocysts don't go it alone. Extrinsic signals fine-tune the intrinsic developmental program of trophoblast cells

The preimplantation embryo floats freely within the oviduct and is capable of developing into a blastocyst independently of the maternal reproductive tract. While establishment of the trophoblast lineage is dependent on expression of developmental regulatory genes, further differentiation leading to blastocyst implantation in the uterus requires external cues emanating from the microenvironment. Recent studies suggest that trophoblast differentiation requires intracellular signaling initiated by uterine-derived growth factors and integrin-binding components of the extracellular matrix. The progression of trophoblast development from the early blastocyst stage through the onset of implantation appears to be largely independent of new gene expression. Instead, extrinsic signals direct the sequential trafficking of cell surface receptors to orchestrate the developmental program that initiates blastocyst implantation. The dependence on external cues could coordinate embryonic activities with the developing uterine endometrium. Biochemical events that regulate trophoblast adhesion to fibronectin are presented to illustrate a developmental strategy employed by the peri-implantation blastocyst.

Significant overexpression of urokinase-type plasminogen activator in pancreatic adenocarcinoma using real-time quantitative reverse transcription polymerase chain reaction

BACKGROUND AND AIMS

Overexpression of urokinase-type plasminogen activator (uPA) has been shown to be strongly associated with an increased metastatic potential and poor prognosis in a variety of human malignancies. It was hypothesized that uPA would be overexpressed in highly metastatic pancreatic cancer. The aims of this study were to analyze uPA mRNA expression in pancreatic cancer and to correlate this to the expression of uPA protein and to the stage of the disease.

METHODS

Twenty-one pancreatic adenocarcinoma, six ampullary carcinoma and 10 benign mucinous cystadenoma samples, all with adjacent normal tissue, were collected. uPA mRNA was measured using real-time quantitative reverse transcription polymerase chain reaction. Localization of uPA within normal and pancreatic tumor sections was subsequently confirmed using immunohistochemistry.

RESULTS

The median and range of the ratios of uPA mRNA measures between tumor tissue and non-involved pancreatic tissue was 17.1 (1.4-653.6) for pancreatic adenocarcinoma (P < 0.001), 3.9 (0.7-7.7) for ampullary carcinoma (P = 0.055) and 1.9 (0.6-5.9) for mucinous cystadenoma tissue (P = 0.052). uPA low tumors were associated with an exuberant stromal reaction, whereas uPA high tumors showed little stromal response. Immunohistochemistry confirmed that uPA protein was more prevalent in pancreatic adenocarcinoma tissue than in normal tissue and that it was membrane-bound. uPA mRNA expression was significantly associated with poorly differentiated pancreatic cancers (P < 0.05) and positively associated with tumor stage.

CONCLUSIONS

These observations suggest that significant overexpression of uPA correlates closely to the rapid progression and invasiveness of pancreatic cancer and that uPA may provide a future therapeutic target for pancreatic cancer treatment.

DU145 human prostate carcinoma invasiveness is modulated by urokinase receptor (uPAR) downstream of epidermal growth factor receptor (EGFR) signaling

Tumor cell motility and invasion have been linked to upregulated signaling from both the epidermal growth factor receptor (EGFR) and that for urokinase-type plasminogen activator (uPAR). However, we do not know whether these events are interdependent or unrelated, despite the obvious diagnostic and therapeutic implications. Gene microarray analyses have suggested that EGFR signaling via phospholipase C-gamma (PLCgamma) induces uPAR transcription. We utilized two sublines of the DU145 human prostate carcinoma cell line that are genetically engineered to differentially activate the EGFR/PLCgamma cascade and are variously invasive in vitro and in vivo. uPAR protein levels in these cells were found to be dependent on PLC signaling, pharmacologic inhibition of PLC signaling reduced uPAR expression. To determine whether uPAR was a required element in EGFR-mediated invasion, we stably expressed uPAR cDNA in either sense or antisense orientation in the two DU145 sublines. Interestingly, uPA production was modulated in parallel, although to a lesser degree, with uPAR in these sublines. Antisense to uPAR significantly restricted invasion of the highly invasive DU145 WT cells through Matrigel and reduced aggressiveness of tumors in nude mice. Up-regulation of uPAR significantly increased the invasiveness of the moderately invasive DU145 parental (DU145 P) cells through Matrigel, but this increased invasiveness was not seen in mice. uPA activity appears to contribute to invasiveness at least through Matrigel, as antibody to uPA or amiloride limited the transmigration. These results support a model of tumor invasion promoted by autocrine EGFR signaling involving reinforcing altered gene expression, of uPAR at least, that further induces cell motility. Herein, a number of key molecules whose expression levels are interrelated, including both EGFR and uPAR, are required but none are sufficient in the absence of other keys molecules in promoting tumor progression.

Factors regulating trophoblast migration and invasiveness: possible derangements contributing to pre-eclampsia and fetal injury

Impaired trophoblast invasiveness and spiral arterial remodelling, which results in poor placental perfusion during early pregnancy, is believed to cause fetal injury and growth retardation, and also endothelial cell activation/dysfunction in a susceptible mother, leading to clinical manifestations of pre-eclampsia. This article briefly reviews the regulatory roles of certain locally active factors in trophoblast migration and invasiveness. This background is then used to discuss and debate whether derangements or dysfunction of some of these factors can manifest as early serum markers predictive of the disease, as opposed to the intermediate and late stage markers which may reflect manifestations and consequences of the disease. Of particular significance are the observed derangements in uPA/uPAR/PAI system, IGFBP-1, HGF, HB-EGF and TGFbeta, factors which are known to regulate trophoblast migration and invasiveness in situ. An emphasis is placed on the need for longitudinal studies in order to identify predictive serum markers which may help strategies for prevention or amelioration of fetal injury and pre-eclampsia.