Growth factor rescue of cytokine mediated trophoblast apoptosis

Rational Design of Nanomedicine for Placental Disorders: Birthing a New Era in Women's Reproductive Health

The placenta is a transient organ that forms during pregnancy and acts as a biological barrier, mediating exchange between maternal and fetal circulation. Placental disorders, such as preeclampsia, fetal growth restriction, placenta accreta spectrum, and gestational trophoblastic disease, originate in dysfunctional placental development during pregnancy and can lead to severe complications for both the mother and fetus. Unfortunately, treatment options for these disorders are severely lacking. Challenges in designing therapeutics for use during pregnancy involve selectively delivering payloads to the placenta while protecting the fetus from potential toxic side effects. Nanomedicine holds great promise in overcoming these barriers; the versatile and modular nature of nanocarriers, including prolonged circulation times, intracellular delivery, and organ-specific targeting, can control how therapeutics interact with the placenta. In this review, nanomedicine strategies are discussed to treat and diagnose placental disorders with an emphasis on understanding the unique pathophysiology behind each of these diseases. Finally, prior study of the pathophysiologic mechanisms underlying these placental disorders has revealed novel disease targets. These targets are highlighted here to motivate the rational design of precision nanocarriers to improve therapeutic options for placental disorders.

Thrombocytes and Platelet-Rich Plasma as Modulators of Reproduction and Fertility

Thrombocytes play an essential role in hemostasis and thrombosis. Moreover, the controlled activation of thrombocytes is required in reproduction and fertility. The platelet-activating factor and the controlled activation of platelets have important roles in folliculogenesis, ovulation, placental development, implantation and embryo development. Activated platelets accumulate in the follicular vessels surrounding the follicle and, due to its released soluble molecules (factors, mediators, chemokines, cytokines, neurotransmitters), locally increase oocyte maturation and hormone secretion. Furthermore, activated platelets are involved in the pathogenesis of ovarian hyperstimulation syndrome (OHSS) and preeclampsia. Low-dose aspirin can prevent OHSS during ovulation induction, while intrauterine or intraovarian administration of platelet-rich plasma (PRP) increases the endometrium thickness and receptivity as well as oocyte maturation. Activated thrombocytes rapidly release the contents of intracellular granules and have multiple adhesion molecules and receptors on their surface. Considering the numerous homeostatic endocrine functions of thrombocytes, it is reasonable to suppose a platelet-associated regulatory system (PARS) in reproduction. Although we are far from a complete understanding of the regulatory processes, the results of PARS research and the therapeutic application of aspirin and PRP during in vitro fertilization are promising.

Neurotrophins: are they involved in immune tolerance in pregnancy?

In this review, an attempt was made to substantiate the possibility for neurotrophins to be involved in the development of immune tolerance based on data accumulated on neurotrophin content and receptor expression in the trophoblast and immune cells, in particular, in natural killer cells. Numerous research results are reviewed to show that the expression and localization of neurotrophins along with their high-affinity tyrosine kinase receptors and low-affinity p75NTR receptor in the mother-placenta-fetus system indicate the important role of neurotrophins as binding molecules in regulating the crosstalk between the nervous, endocrine, and immune systems in pregnancy. An imbalance between these systems can occur with tumor growth and pathological processes observed in pregnancy complications and fetal development anomalies.

Platelet-derived growth factor-AA promotes placental choriocarcinoma JAR cell proliferation via primary cilia

OBJECTIVE

During early pregnancy, the proliferation placental cells is crucial for proper implantation and formation of maternal-fetal circulation. Platelet-derived growth factor-AA (PDGF-AA) has been detected in placenta during early pregnancy; however, the role of PDGF-AA in placental cell growth has not been studied extensively. Primary cilium, a centrosome-based cellular protrusion, is an signaling hub for regulating development and differentiation. Importantly, the receptor of PDGF-AA (Pdgfr-α) is detected in the primary cilium and primary cilia-mediated PDGF-AA signaling regulates development and differentiation. Here we would like to investigate whether PDGF-AA regulates placental cell growth and whether primary cilia play roles in this process.

MATERIALS AND METHODS

Human placental choriocarcinoma JAR cells were treated with PDGF-AA followed by examining cell growth. Primary cilia and subcellular localization of Pdgfr-α were observed by immunofluorescence staining. Manipulation of primary cilia was performed by treating cells with roscovitine or by transfecting cells with siRNA against IFT88.

RESULTS

Here we showed that PDGF-AA induced JAR cell proliferation. In addition, JAR cells grew primary cilia where Pdgfr-α was detected. More importantly, pharmacological inhibition of primary cilia formation or depletion of cilia-related gene, IFT88, alleviated PDGF-AA induced JAR cell proliferation.

CONCLUSION

Thus, our study show that PDGF-AA facilitates human placental choriocarcinomaJARcell growth via primary cilia.

Tumor Necrosis Factor-α Induces a Preeclamptic-like Phenotype in Placental Villi via Sphingosine Kinase 1 Activation

Preeclampsia (PE) involves inadequate placental function. This can occur due to elevated pro-inflammatory tumor necrosis factor-α (TNF-α). In other tissues, TNF-α signals via sphingosine kinase 1 (SphK1). SphK1 hinders syncytial formation. Whether this occurs downstream of TNF-α signaling is unclear. We hypothesized that placental SphK1 levels are higher in PE and elevated TNF-α decreases syncytial function, increases syncytial shedding, and increases cytokine/factor release via SphK1 activity. Term placental biopsies were analyzed for SphK1 using immunofluorescence and qRT-PCR. Term placental explants were treated after 4 days of culture, at the start of syncytial regeneration, with TNF-α and/or SphK1 inhibitors, PF-543. Syncytialization was assessed by measuring fusion and chorionic gonadotropin release. Cell death and shedding were measured by lactate dehydrogenase release and placental alkaline phosphatase-positive shed particles. Forty-two cytokines were measured using multiplex assays. Placental SphK1 was increased in PE. Increased cell death, shedding, interferon-α2, IFN-γ-induced protein 10, fibroblast growth factor 2, and platelet-derived growth factor-AA release induced by TNF-α were reversed upon SphK1 inhibition. TNF-α increased the release of 26 cytokines independently of SphK1. TNF-α decreased IL-10 release and inhibiting SphK1 reversed this effect. Inhibiting SphK1 alone decreased TNF-α release. Hence, SphK1 partially mediates the TNF-α-induced PE placental phenotype, primarily through cell damage, shedding, and specific cytokine release.

Targeted Delivery of Epidermal Growth Factor to the Human Placenta to Treat Fetal Growth Restriction

Placental dysfunction is the underlying cause of pregnancy complications such as fetal growth restriction (FGR) and pre-eclampsia. No therapies are available to treat a poorly functioning placenta, primarily due to the risks of adverse side effects in both the mother and the fetus resulting from systemic drug delivery. The use of targeted liposomes to selectively deliver payloads to the placenta has the potential to overcome these issues. In this study, we assessed the safety and efficacy of epidermal growth factor (EGF)-loaded, peptide-decorated liposomes to improve different aspects of placental function, using tissue from healthy control pregnancies at term, and pregnancies complicated by FGR. Phage screening identified a peptide sequence, CGPSARAPC (GPS), which selectively homed to mouse placentas in vivo, and bound to the outer syncytiotrophoblast layer of human placental explants ex vivo. GPS-decorated liposomes were prepared containing PBS or EGF (50–100 ng/mL), and placental explants were cultured with liposomes for up to 48 h. Undecorated and GPS-decorated liposomes containing PBS did not affect the basal rate of amino acid transport, human chorionic gonadotropin (hCG) release or cell turnover in placental explants from healthy controls. GPS-decorated liposomes containing EGF significantly increased amino acid transporter activity in healthy control explants, but not in placental explants from women with FGR. hCG secretion and cell turnover were unaffected by EGF delivery; however, differential activation of downstream protein kinases was observed when EGF was delivered via GPS-decorated vs. undecorated liposomes. These data indicate that targeted liposomes represent a safe and useful tool for the development of new therapies for placental dysfunction, recapitulating the effects of free EGF.

Cell death mechanisms and their roles in pregnancy related disorders

Autophagy and apoptosis are catabolic pathways essential for homeostasis. They play a crucial role for normal placental and fetal development. These cell death mechanisms are exaggerated in placental disorders such as preeclampsia, intrauterine growth restriction (IUGR) and gestational diabetes mellitus (GDM). Apoptosis is widely studied, highly controlled and regulated whereas; autophagy is an orderly degradation and recycling of the cellular components. Cellular senescence may be initiated by a variety of stimuli, including hypoxia, oxidative stress, reduction in survival signals and nutrition deprivation. Apoptosis is regulated by two types of pathways intrinsic and extrinsic. Extrinsic pathway is initiated by apoptosis inducing cells such as macrophages, natural killer cells whereas; intrinsic pathway is initiated in response to DNA damage, cell injury and lack of oxygen. In autophagy, the cell or organelles undergo lysosomal degradation. Placental apoptosis increases as the gestation progresses while autophagy plays a role in trophoblast differentiation and invasion. In pregnancy disorders like preeclampsia and IUGR, proapoptotic markers such as caspase 3, 8, BAX are higher and antiapoptotic markers like Bcl-2 are lower. In GDM, apoptotic markers are reduced resulting in increased placental mass and fetal macrosomia. Apoptosis in the pathological pregnancies is also influenced by the reduced levels of micronutrients and long chain polyunsaturated fatty acids resulting in disturbed placental biology. This chapter describes the role of various key molecular events involved in cellular senescence and the various factors influencing them. This will help identify future therapeutic strategies for better management of these processes.

Expression and functional role of IGFs during early pregnancy in placenta of water buffalo

Adequate vascularisation is a key factor for successful fetal development. We hypothesized that Insulin-Like Growth Factor (IGF) family members regulate angiogenesis along with promoting fetal development and growth. In this experiment, we determined the expression and functional role of IGF family in placental compartments (caruncle; CAR, cotyledon; COT) during different stages of early pregnancy in the water buffalo (Bubalus bubalis). Samples were collected from early pregnancy 1 (EP1, 28-45 days), early pregnancy 2 (EP2, 45-90 days), and third stage of estrous cycle (11-16 days), which was taken as control. In addition, the role of IGF1 on mRNA expression of vWF, StAR, CYP11A1, 3βHSD, PCNA, and BAX were elucidated in cultured trophoblast cells (TCC) obtained from EP2. Quantitative real-time PCR (q-PCR), westernblot, and immunohistochemistry were done to investigate the gene expression, protein expression, and localization of examined factors, and RIA was also done to assess progesterone (P₄) concentration. Expression of IGFs, its receptors and binding proteins were found to be significantly higher (p < 0.05) in both CAR and COT as compared to control during early pregnancy, except binding proteins IGFBP1, 3 and 4 which were significantly (p < 0.05) downregulated in COT with advancement of pregnancy. mRNA expression was consistent with the findings of immunoblotting and immunolocalization experiments. Trophoblasts cell culture (TCC) study showed a significant time and dose-dependent effect of IGF1 onsteroidogenic transcript, which was found to be maximum at 100 ng/ml that paralleled with P₄ accretion in the media (p < 0.05). Further, IGF1 upregulated the transcripts of vWF, PCNA, and downregulated BAX at the same concentration (p < 0.05). Overall, our results demonstrated that the expression of IGFs is a site-specific phenomenon in placentome, which indicates autocrine/paracrine and endocrine function. Our in-vitro finding support that IGF1 plays a critical role in placental development by promoting angiogenesis, steroid synthesis, and cell proliferation during early pregnancy.

Conditional loss of ERK1 and ERK2 results in abnormal placentation and delayed parturition in the mouse

Extracellular-signal-regulated kinases (ERK) 1 and 2 regulate many aspects of the hypothalamic-pituitary-gonadal axis. We sought to understand the role of ERK1/2 signaling in cells expressing a Cre allele regulated by the endogenous GnRHR promoter (GRIC-ERKdko). Adult female GRIC-ERKdko mice were hypogonadotropic and anovulatory. Gonadotropin administration and mating led to pregnancy in one-third of the ERKdko females. Litters from ERKdko females and pup weights were reduced coincident with delayed parturition and 100% neonatal mortality. Based on this, we examined Cre expression in implantation sites as a potential mechanism. GnRHR mRNA levels at e10.5 and e12.5 were comparable to pituitary levels from adult female mice at proestrus and GnRHR mRNA in decidua was enriched compared to whole implantation site. In vivo studies confirmed recombination in decidua, and GRIC-ERKdko placentas showed reduced ERK2 expression. Histopathology revealed abnormalities in placental architecture in the GRIC-ERKdko animals. Regions of apoptosis at the decidual/uterine interface at e18.5 were observed in control animals but apoptotic tone in these regions was reduced in ERKdko animals. These studies support a potential model of ERK-dependent signaling within the implantation site leading to loss of placental architecture and mis-regulation of apoptotic events at parturition occurring coincident with prolonged gestation and neonatal mortality.

Pharmacological Effect of Quercetin in Hypertension and Its Potential Application in Pregnancy-Induced Hypertension: Review of In Vitro, In Vivo, and Clinical Studies

Since improving maternal and child health is a public health priority worldwide, the main aim of treatment of hypertension in pregnant women is to prevent complications during pregnancy, labor, and postpartum. In consequence, much attention is paid to the use of antihypertensive drugs that can be used safely during pregnancy. Several side effects of methyldopa, which is currently the most commonly used antihypertensive drug in pregnant women, mean that the search for an effective and safe alternative still continues. Flavonoid compounds present in medicinal plants, vegetables, and fruits may be a promising source of new drugs. In this aspect, quercetin, a well-known flavonoid due to its antihypertensive action, may be considered a prototype for safe antihypertensive drugs. This review focuses on the selective activity of quercetin. Based on recent studies, a few problems were discussed, including (1) pathology of pregnancy-induced hypertension; (2) search for new pharmacological treatments of pregnancy-induced hypertension; (3) issues with the use of herbal extracts during pregnancy; (4) flavonoids as natural active chemical compounds; (5) quercetin: its action during pregnancy, in vitro and in vivo pharmacological activities, clinical trials, and meta-analysis; (6) quercetin intake during pregnancy; (7) other natural compounds tested during pregnancy; (8) potential problems with the use of quercetin; (9) safety profile of quercetin. Various studies have shown a beneficial effect of quercetin on vascular endothelial function and its antioxidative and anti-inflammatory activity on cellular and tissue level. It is known that in animal models quercetin affects positively the development of embryo, fetus, and placenta. Because this flavonoid did not have teratogenic and abortive effect, it is generally recognized as safe. For this reason it should be appreciated and studied in the aspect of its potential use in the prevention and treatment of pregnancy-induced hypertension among women in this risk group.

Synergistic effects of tumor necrosis factor-α and insulin-like growth factor-I on survival of human trophoblast-derived BeWo cell line

OBJECTIVE

Trophoblast survival is regulated by cytokines and growth factors. While the pharmacological levels (10-100 ng/mL) of tumor necrosis factor (TNF)- α affect trophoblasts survival in vitro, the effects of the physiological levels (1-10 pg/mL) of TNF-α remain unknown. We investigated the effects of the physiological levels of TNF-α on proliferation and apoptosis of human trophoblast cells by using BeWo cells. Insulin-like growth factor (IGF)-I is also a potent regulator of trophoblast survival and has been known to exert synergistic effects with other hormones. The interaction of IGF-I and TNF-α on BeWo cells survival was also examined.

METHODS

After incubating BeWo under the presence of TNF-α (10-10⁵ pg/mL) and IGF-I (10² ng/mL), we assessed cell number by WST-1 assay and cell proliferation by BrdU uptake assay and immunocytochemistry with anti-Ki67 antibody. Apoptosis was evaluated by TUNEL assay and caspase-3, 8 activity assays.

RESULTS

Under the presence of IGF-I, cell number, BrdU uptake, and Ki-67 expression of BeWo were dose-dependently enhanced by low TNF-α (10-10² pg/mL), while no such effects were detected without IGF-I. Higher levels of TNF-α (10⁴-10⁵ pg/mL) showed inhibiting effects on cell number and cell proliferation. The number of TUNEL positive cells were decreased and caspase activities were suppressed by lower levels (10-10² pg/mL) of TNF-α and IGF-I independently. Higher levels of TNF-α (10⁴-10⁵ pg/mL) showed promoting effects on apoptosis irrespective of IGF-I.

CONCLUSION

The physiological levels of TNF-α and IGF-I had synergetic effects on enhancing cell proliferation and also independently inhibited apoptosis of Bewo cells.

Differential expression of leukemia inhibitory factor and insulin like growth factor-1 between normal pregnancies, partial hydatidiform moles and complete hydatidiform moles

INTRODUCTION

Leukemia inhibitory factor (LIF) and insulin like growth factor-1 (IGF-1) are two of the most important growth factors mediating trophoblast actions. We hypothesized that the localization and expression patterns of LIF and IGF-1 in partial and complete hydatidiform moles (HM) compared with normal first trimester placentas may provide an understanding of the proliferative processes in HMs.

METHODS

The study population included curettage material of women diagnosed as complete or partial HM as a result of histopathological and immunohistochemical examination (complete HM group, n = 8; partial HM group, n = 8) and women undergoing dilatation&curettage for unwanted pregnancies (control group, n = 8). Expression of LIF and IGF-1 among placental cell groups was evaluated immunohistochemically and given a score depending on immunostaining intensity.

RESULTS

In normal chorionic villi strong expression of LIF and IGF-1 was present. Both LIF and IGF-1 expressions were weaker in the chorionic villi of complete HMs. In complete mole decidua there was a significant decrease in glandular and endothelial IGF-1 expression along with a decrease in decidual cell LIF expression compared to normal first trimester decidua. LIF expression in extravillous trophoblasts was stronger in complete molar placentas compared to normal placentas.

DISCUSSION

LIF and IGF-1 are important regulators of trophoblast proliferation and invasion. Differential expression of LIF and IGF-1 in molar trophoblasts and chorionic villi might have a role in regulation of trophoblasts in complete moles. Decreased expression of glandular IGF-1 and decidual LIF might be related to the decidual changes during trophoblastic proliferation and invasion of decidua in complete HMs.

Antigenic binding sites of anti-protein S autoantibodies in patients with recurrent pregnancy loss

BACKGROUND

Protein S (PS) deficiency is a risk factor for adverse pregnancy outcomes including recurrent pregnancy loss. Several studies have shown that the presence of anti-PS autoantibodies (anti-PS) leads to an acquired PS deficiency. Hence, an epitope mapping study was conducted to know the pathogenesis of anti-PS in patients with recurrent pregnancy loss.

METHODS

PS was treated with thrombin to divide the protein into γ-carboxyglutamic acid (Gla) domain and Gla-domain free PS. For the preparation of fragments of epidermal growth factor (EGF)-like domains (EGF1-4), PS was subjected to proteolysis using lysyl endopeptidase. The epitopes were identified in immunoblot. Whether anti-PS recognized EGF family proteins in anti-PS-positive patients was also examined.

RESULTS

Anti-PS recognized Gla-domain free PS, especially the three fragments of EGF-like domains, EGF1-2, EGF3-4, and EGF1-4. Anti-PS recognized recombinant human EGF. Anti-PS and polyclonal antibodies to recombinant human EGF recognized PS in the absence of Ca2+ but not in the presence of Ca2+. In competitive inhibition studies, polyclonal antibodies to recombinant mouse EGF blocked anti-PS binding to PS in a concentration-dependent manner.

CONCLUSIONS

These results suggest that anti-PS in patients with recurrent pregnancy loss recognize EGF-like domains in PS. Interestingly, anti-PS also recognized EGF family proteins. Anti-PS in patients with recurrent pregnancy loss may be associated with not only thrombophilia but also the disruption of the EGF system.

Dydrogesterone and the immunology of pregnancy

Progesterone is indispensable for the maintenance of pregnancy, both via its endocrine effects and its role in creating a favorable immunological environment for the fetus. This review focuses on the immunological effects of progesterone. Progestogens have been shown to have very interesting effects on cytokine production and decidual natural killer (NK) cell activity. The orally-administered progestogen, dydrogesterone, has the ability to modulate cytokine production patterns in a manner that could be conducive to successful pregnancy. The adverse effects of progesterone deficiency and the beneficial effects of progesterone supplementation in pregnancy pathologies will be discussed.

An Integrative Analysis of Preeclampsia Based on the Construction of an Extended Composite Network Featuring Protein-Protein Physical Interactions and Transcriptional Relationships

Preeclampsia (PE) is a pregnancy disorder defined by hypertension and proteinuria. This disease remains a major cause of maternal and fetal morbidity and mortality. Defective placentation is generally described as being at the root of the disease. The characterization of the transcriptome signature of the preeclamptic placenta has allowed to identify differentially expressed genes (DEGs). However, we still lack a detailed knowledge on how these DEGs impact the function of the placenta. The tools of network biology offer a methodology to explore complex diseases at a systems level. In this study we performed a cross-platform meta-analysis of seven publically available gene expression datasets comparing non-pathological and preeclamptic placentas. Using the rank product algorithm we identified a total of 369 DEGs consistently modified in PE. The DEGs were used as seeds to build both an extended physical protein-protein interactions network and a transcription factors regulatory network. Topological and clustering analysis was conducted to analyze the connectivity properties of the networks. Finally both networks were merged into a composite network which presents an integrated view of the regulatory pathways involved in preeclampsia and the crosstalk between them. This network is a useful tool to explore the relationship between the DEGs and enable hypothesis generation for functional experimentation.

Proline-arginine rich (PR-39) cathelicidin: Structure, expression and functional implication in intestinal health

Proline-Arginine-39 (PR-39) is a small cationic, proline and arginine rich, cathelicidin that plays an important role in the porcine innate immune system. Although PR-39 was first discovered in intestinal cell lysates of pigs, subsequent research has indicated that it is primarily expressed in bone marrow and other lymphoid tissues including the thymus and spleen, as well as in leukocytes. Mature PR-39 cathelicidin has anti-microbial activity against many gram-negative and some gram-positive bacteria. PR-39 is also a bridge between the innate and adaptive immune system with recognized immunomodulatory, wound healing, anti-apoptotic, and pro-angiogenic functions. The purpose of this review is to summarize our current knowledge about the structure, expression, and functions of PR-39 and its potential to promote intestinal homeostasis. This understanding is relevant in the search of alternative therapeutics against diarrheic enterocolitis, a major problem faced by pork producers both in terms of costs and risk of zoonosis.

Exposure to Fine Particulate Air Pollution Is Associated With Endothelial Injury and Systemic Inflammation

RATIONALE

Epidemiological evidence indicates that exposures to fine particulate matter air pollution (PM_2.5) contribute to global burden of disease, primarily as a result of increased risk of cardiovascular morbidity and mortality. However, mechanisms by which PM_2.5 exposure induces cardiovascular injury remain unclear. PM_2.5-induced endothelial dysfunction and systemic inflammation have been implicated, but direct evidence is lacking.

OBJECTIVE

To examine whether acute exposure to PM_2.5 is associated with endothelial injury and systemic inflammation.

METHODS AND RESULTS

Blood was collected from healthy, nonsmoking, young adults during 3 study periods that included episodes of elevated PM_2.5 levels. Microparticles and immune cells in blood were measured by flow cytometry, and plasma cytokine/growth factors were measured using multiplexing laser beads. PM_2.5 exposure was associated with the elevated levels of endothelial microparticles (annexin V⁺/CD41^-/CD31⁺), including subtypes expressing arterial-, venous-, and lung-specific markers, but not microparticles expressing CD62⁺. These changes were accompanied by suppressed circulating levels of proangiogenic growth factors (EGF [epidermal growth factor], sCD40L [soluble CD40 ligand], PDGF [platelet-derived growth factor], RANTES [regulated on activation, normal T-cell-expressed and secreted], GROα [growth-regulated protein α], and VEGF [vascular endothelial growth factor]), and an increase in the levels of antiangiogenic (TNFα [tumor necrosis factor α], IP-10 [interferon γ-induced protein 10]), and proinflammatory cytokines (MCP-1 [monocyte chemoattractant protein 1], MIP-1α/β [macrophage inflammatory protein 1α/β], IL-6 [interleukin 6], and IL-1β [interleukin 1β]), and markers of endothelial adhesion (sICAM-1 [soluble intercellular adhesion molecule 1] and sVCAM-1 [soluble vascular cellular adhesion molecule 1]). PM_2.5 exposure was also associated with an inflammatory response characterized by elevated levels of circulating CD14⁺, CD16⁺, CD4⁺, and CD8⁺, but not CD19⁺ cells.

CONCLUSIONS

Episodic PM_2.5 exposures are associated with increased endothelial cell apoptosis, an antiangiogenic plasma profile, and elevated levels of circulating monocytes and T, but not B, lymphocytes. These changes could contribute to the pathogenic sequelae of atherogenesis and acute coronary events.

The Influence of Oxygen and Tumor Necrosis Factor-α on the Cellular Kinetics of Term Placental Villous Explants in Culture

Explanted placental fragments may provide a more physiological in vitro model of component cell function than single cell isolates. We have characterized these fragments for cell turnover and have monitored responses from 14 normal placentas under conditions of exogenous TNFα and atypical oxygen concentrations (3% and 17%), conditions associated with abnormal pregnancy and an aberrant in utero environment. Explants were assessed for apoptotic morphology, immunolocalization of Mib-1 (a proliferation marker), caspase 3 activity (an apoptosis promoter), lactate dehydrogenase (a necrosis marker), and human chorionic gonadotrophin [hCG, a marker of cytotrophoblast (CT) differentiation]. Consistent with a reduction in hCG, explants under 17% O2 (with and without TNFα) showed a progressive degeneration of syncytiotrophoblast (ST) (days 0–2) followed by a restoration of hCG (days 4–8) localized to newly differentiated but not syncytialized CTs. In 3% O2, hCG showed the same initial decline but failed to recover thereafter. Proliferation dropped significantly in 17% O2 but was restored and exaggerated sixfold in 3% O2. All reductions in hCG were associated with cell death and caspase-3. Early apoptosis was linked with syncytial loss; later apoptosis (days 8–11) was localized to the non-ST. Prolonged exposure to TNFα (days 4–11) increased ST apoptosis and necrosis but 3% O2 had no significant effect. These findings show that placental explants can accommodate many aspects of CT proliferation, differentiation, and ST apoptosis in culture. TNFα enhanced ST decline but 3% oxygen (compared with 17%) was associated with reduced CT differentiation and a strong shift towards proliferation. These outcomes may reflect previous morphological changes in compromised pregnancies and confirm a possible role for oxygen and TNFα in aberrant trophoblast turnover.

TNF-α stimulates System A amino acid transport in primary human trophoblast cells mediated by p38 MAPK signaling

Maternal obesity and gestational diabetes mellitus (GDM) increase the risk of delivering infants that are large for gestational age with greater adiposity, who are prone to the development of metabolic disease in childhood and beyond. These maternal conditions are also associated with increased levels of the proinflammatory cytokine TNF-α in maternal tissues and the placenta. Recent evidence suggests that changes in placental amino acid transport contribute to altered fetal growth. TNF-α was previously shown to stimulate System A amino acid transport in primary human trophoblasts (PHTs), however the molecular mechanisms remain unknown. In this study, we tested the hypothesis that TNF-α regulates amino acid uptake in cultured PHTs by a mitogen-activated protein kinase (MAPK)-dependent mechanism. Treatment of PHTs with TNF-α significantly increased System A amino acid transport, as well as Erk and p38 MAPK signaling. Pharmacological antagonism of p38, but not Erk MAPK activity, inhibited TNF-α stimulated System A activity. Silencing of p38 MAPK using siRNA transfections prevented TNF-α stimulated System A transport in PHTs. TNF-α significantly increased the protein expression of System A transporters SNAT1 and SNAT2, but did not affect their mRNA expression. The effects of TNF-α on SNAT1 and SNAT2 protein expression were reversed by p38 MAPK siRNA silencing. In conclusion, TNF-α regulates System A activity through increased SNAT1 and SNAT2 transporter protein expression in PHTs. These findings suggest that p38 MAPK may represent a critical mechanistic link between elevated proinflammatory cytokines and increased placental amino acid transport in obese and GDM pregnancies associated with fetal overgrowth.

Noninvasive detection of trophoblast protein signatures linked to early pregnancy loss using trophoblast retrieval and isolation from the cervix (TRIC)

OBJECTIVE

To examine the expression pattern of biomarker proteins in extravillous trophoblast (EVT) cells obtained noninvasively by trophoblast retrieval and isolation from the cervix (TRIC) in patients with early pregnancy loss compared with control patients with uncomplicated term delivery.

DESIGN

Case-control study.

SETTING

Academic medical center.

PATIENT(S)

Women with either early pregnancy loss (EPL, n = 10) or an uncomplicated term delivery (N = 10).

INTERVENTION(S)

Endocervical specimens obtained from ongoing pregnancies at gestational ages of 5-10 weeks to generate an archive of EVT cells isolated by TRIC, with medical records examined to select specimens matched for gestational age at the time of endocervical sampling.

MAIN OUTCOME MEASURE(S)

Known serum biomarkers for adverse pregnancy outcome that are expressed by EVT cells were evaluated by semiquantitative immunocytochemistry, using antibodies against endoglin (ENG), FMS-like tyrosine kinase-1 (FLT-1), α-fetoprotein (AFP), pregnancy-associated plasma protein-A (PAPP-A), galectin-13 (LGALS13), galectin-14 (LGALS14), and placental growth factor (PGF).

RESULT(S)

The EVT purity was over 95% in all specimens, based on chorionic gonadotropin expression; however, the number of EVT cells obtained was significantly lower in women with EPL than the control group. There was a statistically significant elevation of AFP, ENG, and FLT-1, and statistically significant reduction of PAPP-A, LGALS14, and PGF in the EPL group compared with controls.

CONCLUSION(S)

In this pilot study, EVT cells isolated by TRIC early in gestation exhibited altered protein expression patterns before an EPL compared with uncomplicated term pregnancies.

Reduced expression of the epidermal growth factor signaling system in preeclampsia

INTRODUCTION

The epidermal growth factor (EGF) signaling system regulates trophoblast differentiation, and its disruption could contribute to perinatal disease. We hypothesized that this pathway is altered in preeclampsia, a disorder associated with trophoblast apoptosis and failure to invade and remodel the uterine spiral arteries.

METHODS

Six EGF family peptides and a truncated EGF receptor splice variant (p110/EGFR) were examined using immunohistochemistry in the trophoblast of placentas (N = 76) from women with preeclampsia, and compared to placentas from women of similar gestational age (GA) with preterm labor (PTL) or small for gestational age (SGA) fetuses, as well as normal term placentas. EGF, transforming growth factor-α (TGFA), and heparin-binding EGF-like growth factor (HBEGF) were evaluated using ELISA in maternal plasma from another 20 pregnancies with or without preeclampsia. Cell death was evaluated in the HTR-8/SVneo human cytotrophoblast cell line using TUNEL to evaluate the protective effects of EGF peptides.

RESULTS

Trophoblast HBEGF, TGFA, and EGF were significantly reduced in preeclampsia compared to PTL and SGA, while p110/EGFR accumulated significantly on the surface of the chorionic villi (p < 0.05). Plasma EGF levels were significantly decreased in preeclamptic patients, compared to non-preeclamptic patients (p < 0.05). HBEGF, EGF, TGFA, epiregulin, and betacellulin each blocked cytotrophoblast cell death in vitro (p < 0.05).

DISCUSSION

Three members of the EGF family are dysregulated in placentas with preeclampsia, whereas p110/EGFR, a potential EGF receptor antagonist, is overexpressed. These findings are consistent with the concept that disruption of the EGF signaling system contributes to aberrant trophoblast development associated with preeclampsia.

The role of VEGF-A165b in trophoblast survival

Background

Pre-eclampsia remains a dominant cause of maternal and fetal mortality in developed countries. In a previous prospective study we identified a fall in the VEGF-A isoform VEGF-A₁₆₅b in the plasma of patients in the first trimester to be a predictor of later pre-eclampsia. VEGF-A₁₆₅b has been shown to have potent cytoprotective properties in many cell types. We therefore tested the hypothesis that VEGF-A₁₆₅b may be cytoprotective for placental trophoblasts.

Methods

We used an immortalised first trimester trophoblast cell line exposed to chemical toxicity, and physiological (<2% O₂) and atmospheric oxygen (21% O₂) in the presence or absence of VEGF-A₁₆₅b, angiogenic VEGF-A₁₆₅a, a non-specific anti-VEGF-A blocking antibody (bevacizumab), or a specific anti-VEGF-A₁₆₅b antibody. Cell viability and cytotoxicity were measured by trypan blue and LDH assay respectively.

Results

Under high (21%) levels of oxygen, trophoblast viability was increased, and cytotoxicity reduced by exogenous recombinant VEGF-A₁₆₅b (p < 0.05, n = 10) or VEGF-A₁₆₅a. The cytoprotective effect was not seen under lower (<2%) oxygen conditions, where VEGF-A₁₆₅b was upregulated. However inhibition of VEGF-A with blocking antibodies (bevacizumab or anti-VEGF-A₁₆₅b) had marked cytotoxic effects under low oxygen conditions presumably through the blockade of autocrine survival pathways.

Conclusions

These results show that when trophoblasts are exposed to lower oxygen tensions (as they are early in the 1^st trimester) endogenous VEGF-A₁₆₅b contributes to their survival through an autocrine pathway. In contrast in high oxygen conditions exogenous VEGF-A isoforms have a greater effect on trophoblast survival.

"Platelet-associated regulatory system (PARS)" with particular reference to female reproduction

Background

Blood platelets play an essential role in hemostasis, thrombosis and coagulation of blood. Beyond these classic functions their involvement in inflammatory, neoplastic and immune processes was also investigated. It is well known, that platelets have an armament of soluble molecules, factors, mediators, chemokines, cytokines and neurotransmitters in their granules, and have multiple adhesion molecules and receptors on their surface.

Methods

Selected relevant literature and own views and experiences as clinical observations have been used.

Results

Considering that platelets are indispensable in numerous homeostatic endocrine functions, it is reasonable to suppose that a platelet-associated regulatory system (PARS) may exist; internal or external triggers and/or stimuli may complement and connect regulatory pathways aimed towards target tissues and/or cells. The signal (PAF, or other tissue/cell specific factors) comes from the stimulated (by the e.g., hypophyseal hormones, bacteria, external factors, etc.) organs or cells, and activates platelets. Platelet activation means their aggregation, sludge formation, furthermore the release of the for-mentioned biologically very powerful factors, which can locally amplify and deepen the tissue specific cell reactions. If this process is impaired or inhibited for any reason, the specifically stimulated organ shows hypofunction. When PARS is upregulated, organ hyperfunction may occur that culminate in severe diseases.

Conclusion

Based on clinical and experimental evidences we propose that platelets modulate the function of hypothalamo-hypophyseal-ovarian system. Specifically, hypothalamic GnRH releases FSH from the anterior pituitary, which induces and stimulates follicular and oocyte maturation and steroid hormone secretion in the ovary. At the same time follicular cells enhance PAF production. Through these pathways activated platelets are accumulated in the follicular vessels surrounding the follicle and due to its released soluble molecules (factors, mediators, chemokines, cytokines, neurotransmitters) locally increase oocyte maturation and hormone secretion. Therefore we suggest that platelets are not only a small participant but may be the conductor or active mediator of this complex regulatory system which has several unrevealed mechanisms. In other words platelets are corpuscular messengers, or are more than a member of the family providing hemostasis.

Transcriptomic signature to oxidative stress exposure at the time of embryonic genome activation in bovine blastocysts

In order to understand how in vitro culture affects embryonic quality, we analyzed survival and global gene expression in bovine blastocysts after exposure to increased oxidative stress conditions. Two pro-oxidant agents, one that acts extracellularly by promoting reactive oxygen species (ROS) production (0.01 mM 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) or another that acts intracellularly by inhibiting glutathione synthesis (0.4 mM buthionine sulfoximine [BSO]) were added separately to in vitro culture media from Day 3 (8-16-cell stage) onward. Transcriptomic analysis was then performed on resulting Day-7 blastocysts. In the literature, these two pro-oxidant conditions were shown to induce delayed degeneration in a proportion of Day-8 blastocysts. In our experiment, no morphological difference was visible, but AAPH tended to decrease the blastocyst rate while BSO significantly reduced it, indicating a differential impact on the surviving population. At the transcriptomic level, blastocysts that survived either pro-oxidant exposure showed oxidative stress and an inflammatory response (ARRB2), although AAPH induced higher disturbances in cellular homeostasis (SERPINE1). Functional genomics of the BSO profile, however, identified differential expression of genes related to glycine metabolism and energy metabolism (TPI1). These differential features might be indicative of pre-degenerative blastocysts (IGFBP7) in the AAPH population whereas BSO exposure would select the most viable individuals (TKDP1). Together, these results illustrate how oxidative disruption of pre-attachment development is associated with systematic up-regulation of several metabolic markers. Moreover, it indicates that a better capacity to survive anti-oxidant depletion may allow for the survival of blastocysts with a quieter metabolism after compaction.

Maternal serum insulin-like growth factor-I at 11-13 weeks in preeclampsia

OBJECTIVE

To investigate the maternal serum concentration of insulin-like growth factor-I (IGF-I) in the first trimester of pregnancies that subsequently develop preeclampsia (PE) and to examine the possible association with uterine artery pulsatility index (PI).

METHODS

The maternal serum concentration of IGF-I and uterine artery PI at 11-13 weeks were measured in 53 cases that developed PE, including 18 that required delivery before 34 weeks (early-PE) and 106 unaffected controls. The measured IGF-I concentration and uterine artery PI were converted into a multiple of the expected median (MoM) in unaffected pregnancies, and median MoM values were compared in the outcome groups. The significance of association of IGF-I MoM with uterine artery PI MoM was determined by regression analysis.

RESULTS

In the early-PE and late-PE groups, compared to the unaffected controls, the median IGF-I decreased (0.53 and 0.55 MoM, respectively) and uterine artery PI increased (1.55 and 1.21 MoM, respectively). In the group that developed PE, there was no significant association between serum IGF-I and uterine artery PI (p = 0.632).

CONCLUSION

In pregnancies destined to develop PE, the circulating levels of IGF-I decrease from the first trimester of pregnancy suggesting that IGF-I may be implicated in the pathogenesis of the disease.

Gene expression analysis of bovine blastocysts produced by parthenogenic activation or fertilisation

The processes underlying the very first moments of embryonic development are still not well characterised in mammals. To better define the kinetics of events taking place following fertilisation, it would be best to have perfect synchronisation of sperm entry. With fertilisation occurring during a time interval of 6 to 12 h in the same group of fertilised oocytes, this causes a major variation in the time of activation of embryonic development. Bovine parthenogenesis could potentially result in better synchronisation and, if so, would offer a better model for studying developmental competence. In the present study, bovine oocytes were either parthenogenetically activated or fertilised and cultured in vitro for 7 days. Gene expression analysis for those two groups of embryos at early and expanded stages was performed with BlueChip, a customised 2000-cDNA array developed in our laboratory and enriched in clones from various stages of bovine embryo development. The microarray data analysis revealed that only a few genes were differentially expressed, showing the relative similarity between those two kinds of embryos. Nevertheless, the fact that we obtained a similar diversity of developmental stages with parthenotes suggests that synchronisation is more oocyte-specific than sperm entry-time related. We then analysed our data with Ingenuity pathway analysis. Networks of genes involved in blastocyst implantation but also previous stages of embryo development, like maternal-to-embryonic transition, were identified. This new information allows us to better understand the regulatory mechanisms of embryonic development associated with embryo status.

Thrombophilic-type placental pathologies and skeletal growth delay following maternal administration of angiostatin4.5 in mice

During placentation, the concentration of fibrinous deposits on the surfaces of maternal vasculature plays a role in villous development and has been strongly implicated in the pathophysiology of human fetal growth restriction (FGR). Fibrinous deposits are conspicuous sites of platelet aggregation where there is local activation of the hemostatic cascade. During activation of the hemostatic cascade, a number of pro- and antiangiogenic agents may be generated at the cell surface, and an imbalance in these factors may contribute to the placental pathology characteristic of FGR. We tested the hypothesis that angiostatin(4.5) (AS(4.5)), a cleavage fragment of plasminogen liberated at the cell surface, is capable of causing FGR in mice. Increased maternal levels of AS(4.5) in vivo result in reproducible placental pathology, including an altered vascular compartment (both in decidual and labyrinthine layers) and increased apoptosis throughout the placenta. In addition, there is significant skeletal growth delay and conspicuous edema in fetuses from mothers that received AS(4.5). Maternally generated AS(4.5), therefore, can access maternal placental vasculature and have a severe effect on placental architecture and inhibit fetal development in vivo. These findings strongly support the hypothesis that maternal AS(4.5) levels can influence placental development, possibly by directly influencing trophoblast turnover in the placenta, and contribute to fetal growth delay in mice.

Epidermal growth factor (EGF) induces motility and upregulates MMP-9 and TIMP-1 in bovine trophoblast cells

Differentiation and restricted invasion/migration of trophoblast cells are crucial for feto-maternal communication in the synepitheliochorial placenta of cattle. EGF is expressed in the bovine placenta and likely regulates these cell properties. As cell migration and motility rely on the degradation of extracellular matrix we hypothesize that EGF is involved in the regulation of the MMP-9/TIMP-1 balance and thus could influence trophoblast migration, tissue remodeling, and the release of the fetal membranes after parturition. The aim of this in vitro study was to examine EGF-mediated effects on cell motility, proliferation, and MMP-9 and TIMP-1 expression in cultured bovine trophoblast cells. We used a trophoblast cell line (F3) derived from bovine placentomes to examine the influence of EGF on MMP-9 and TIMP-1 expression by semiquantitative RT-PCR and MMP activity by zymography. Migration assays were performed using a Boyden chamber and cell motility was measured by time-lapse analyses. To identify the involved signaling cascades, phosphorylation of mitogen-activated protein kinase (MAPK) 42/44 and Akt was detected by Western blot. EGF treatment increased both the abundance of MMP-9 and TIMP-1 mRNAs and the proteolytic activity of MMP-9. Furthermore, EGF stimulated proliferation and migration of F3 cells. Addition of specific inhibitors of MAPK (PD98059) and/or PI3K (LY294002) activation abolished or reduced EGF-induced effects in all experiments. In conclusion, EGF-mediated effects stimulate migration and proliferation of bovine trophoblast cells and may be involved in bovine placental tissue remodeling and postpartum release of fetal membranes.

The neglected role of insulin-like growth factors in the maternal circulation regulating fetal growth

Maternal insulin-like growth factors (IGFs) play a pivotal role in modulating fetal growth via their actions on both the mother and the placenta. Circulating IGFs influence maternal tissue growth and metabolism, thereby regulating nutrient availability for the growth of the conceptus. Maternal IGFs also regulate placental morphogenesis, substrate transport and hormone secretion, all of which influence fetal growth either via indirect effects on maternal substrate availability, or through direct effects on the placenta and its capacity to supply nutrients to the fetus. The extent to which IGFs influence the mother and/or placenta are dependent on the species and maternal factors, including age and nutrition. As altered fetal growth is associated with increased perinatal morbidity and mortality and a greater risk of developing degenerative diseases in adult life, understanding the role of maternal IGFs during pregnancy is essential in order to identify mechanisms underlying altered fetal growth and offspring programming.

Regulation of trophoblast migration and survival by a novel neural regeneration peptide

Although placental trophoblast migration is tightly controlled in an autocrine/paracrine manner, the nature of chemoattractive factors facilitating and directing this biological activity remains largely elusive. Neural regeneration peptides (NRP), a recently discovered peptide family, stimulate neuronal migration, differentiation and survival of post-natal neurons within the murine central nervous system. Based on the neural-repair related activities of these peptides and parallels between neuronal and placental cell behaviour patterns, this study postulated that they play a role in placental development, in particular trophoblast migration and survival and investigated the role of a newly discovered NRP motif (NNZ-4920), which exhibits about 70% homology to the mouse NRP motif sequence and is homologous to a 13-mer fragment within the N-terminus of human CAPS2, in trophoblast migration and survival regulation. NNZ-4920 significantly enhanced trophoblast migration by 51% (P<0.01) compared with controls and protected against stress induced by serum withdrawal and tumour necrosis factor-alpha/interferon-gamma treatment, at femtomolar concentrations, with efficacy similar to epidermal growth factor. CAPS2 expression was detected in purified term trophoblast and decidual cells. In conclusion, the placenta may be a source of NRP-related gene expression. Its encoded peptide products exert biological effects on term trophoblast migration and survival in vitro.

Effect of pituitary growth hormone and insulin-like growth factor type-I on proliferation, apoptosis and hormone secretion of the placental cell line JEG-3

OBJECTIVE

Placenta human choriocarcinoma JEG-3 cells were used to study the possibility that pituitary growth hormone (GH) and insulin-like growth factor type I (IGF-I) act on first trimester of pregnancy progesterone (P4) and human chorionic gonadotropin (hCG) secretion, cell proliferation and apoptosis.

MATERIAL AND METHODS

The JEG-3 cell line was cultured in Dulbecco modified eagle medium without phenol red containing 10% FBS. The cells were plated in 96-well plates at the density of 3 x 10(3) for 24 h and treated with 10, 50, 100, or 200 ng/ml of GH or 10, 30, 100, or 250 ng/ml of IGF-I for 24 h. At the end of the culture period, cell proliferation was measured using the BrdU colorimetric assay and caspase-3 activity, as a marker of apoptosis, was determined by the colorimetric method. Media were frozen for hormone analysis by enzyme immunoassay. Results. We found that the stimulatory activities of GH and IGF-I on both P4 and hCG secretion paralleled the stimulation of cell proliferation and inhibition of apoptosis.

CONCLUSION

Our findings suggest an important role for pituitary GH and IGF-I in normal placental function during the first trimester of pregnancy.

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.

Intrauterine fate of invasive trophoblast cells

Invasion of trophoblast cells into the uterine spiral arteries and the uterine wall is characteristic of hemochorial placentation. In the rat, trophoblast cells penetrate through the uterine decidua and well into the metrial gland. In this report, we examined the fate of these invasive trophoblast cells following parturition. Invasive trophoblast endocrine cells were retained in the postpartum mesometrial uterus in the rat. The demise of invasive trophoblast cells was followed by the appearance of differentiated smooth muscle cells surrounding blood vessels previously lined by invasive trophoblast cells and an infiltration of macrophages. Regulation of intrauterine trophoblast cell fate was investigated following premature removal of the fetus or removal of the fetus and chorioallantoic placenta. The presence of the fetus affected the distribution of invasive trophoblast cells within the uterus but did not negatively impact their survival. Premature removal of all chorioallantoic placentas and associated fetuses from a uterus resulted in extensive removal of intrauterine trophoblast cells. In summary, the postpartum demise of intrauterine invasive trophoblast cells is a dynamic developmental event regulated in part by the removal of trophic signals emanating from the chorioallantoic placenta.

Human tumour necrosis factor: physiological and pathological roles in placenta and endometrium

The cytokine tumour necrosis factor alpha (TNF) is a well known member of the TNF superfamily consisting of at least 18 ligands and 29 different receptors involved in numerous cellular processes. TNF signals through two distinct receptors TNFR1 and TNFR2 thereby controlling expression of cytokines, immune receptors, proteases, growth factors and cell cycle genes which in turn regulate inflammation, survival, apoptosis, cell migration, proliferation and differentiation. Since expression of TNF was discovered in amnion and placenta many studies demonstrated the presence of the cytokine and its receptors in the diverse human reproductive tissues. Whereas TNF has been implicated in ovulation, corpus luteum formation and luteolysis, this review focuses on the functions of TNF in human placental, endometrial and decidual cell types of normal tissues and also discusses its role in endometrial and gestational diseases. Physiological levels of the cytokine could be important for balancing cell fusion and apoptotic shedding of villous trophoblasts and to limit trophoblast invasion into maternal decidua. Regulation of the TNF/TNFR system by steroid hormones also suggests a role in uterine function including menstrual cycle-dependent destruction and regeneration of endometrial tissue. Aberrant levels of TNF, however, are associated with diverse reproductive diseases such as amniotic infections, recurrent spontaneous abortions, preeclampsia, preterm labour or endometriosis. Hence, concentrations, receptor distribution and length of stimulation determine whether TNF has beneficial or adverse effects on female reproduction and pregnancy.

Expression of heparin-binding EGF-like growth factor in term chorionic villous explants and its role in trophoblast survival

Heparin-binding EGF-like growth factor (HBEGF) induces trophoblast extravillous differentiation and prevents apoptosis. These functions are compromised in preeclampsia. Because HBEGF is downregulated in placentas delivered by women with preeclampsia, we have examined its expression and cytoprotective activity in term villous explants. Chorionic villous explants prepared from non-pathological placentas collected by cesarean section at term were cultured at either 20% or 2% O2 and treated with the HBEGF antagonist CRM197 or recombinant HBEGF. Paraffin sections were assayed for trophoblast death, proliferation and HBEGF expression using the TUNEL method, immunohistochemistry for nuclear Ki67 expression and semi-quantitative immunohistochemistry with image analysis, respectively. Trophoblast cell death was increased significantly after 8h of culture with CRM197 or by culture for 2h at 2% O2. Exogenous HBEGF prevented cell death due to hypoxia. Proliferative capacity was not affected by culture at either 20% or 2% O2. Contrary to first trimester placenta, term trophoblasts do not elevate HBEGF expression in response to hypoxia. However, low endogenous levels of HBEGF are required to maintain survival. Therefore, HBEGF-mediated signaling significantly reduces trophoblast cell death at term and its deficiency in preeclampsia could negatively impact trophoblast survival.

Epidermal growth factor abrogates hypoxia-induced apoptosis in cultured human trophoblasts through phosphorylation of BAD Serine 112

We tested the hypothesis that epidermal growth factor (EGF) limits hypoxia-induced apoptosis in cultured human trophoblasts by phosphorylation of the proapoptotic protein Bcl-2-associated death promoter (BAD). Cytotrophoblasts were isolated from placentas of uncomplicated pregnancies at 38-40 wk gestation. Primary trophoblasts or transfected JEG3 trophoblast cells were cultured in less than 1 or 20% oxygen in the presence or absence of EGF and signaling pathway inhibitors. BAD, green fluorescent protein (GFP)-BAD, 14-3-3, Bcl-X(L), and neoepitopes formed during apoptotic cleavage of cytokeratin 18 intermediate filaments were quantified using immunoblotting. Cultures immunostained by fluorescent antibodies were analyzed by confocal microscopy for BAD and GFP. Fluorescence resonance energy transfer was used to detect molecular interaction between endogenous BAD and GFP-BAD. We found EGF increased the phosphorylation of BADser112 under standard culture conditions. Whereas hypoxia enhanced apoptosis and increased phosphorylation of both BADser136 and BADser155, hypoxia diminished phosphorylation of BADser112, and this effect was reversible by EGF. Transfected GFP-BAD, which directly interacted with endogenous BAD by colocalization and fluorescence resonance energy transfer, enhanced hypoxia-induced apoptosis in JEG3 cells. EGF reduced apoptosis in hypoxic JEG3 cells that overexpressed GFP-BAD but not in cells overexpressing GFP-BAD that harbored a serine-to-alanine mutation at the 112 site. Coimmunoprecipitation studies showed that EGF reduced the proapoptotic interaction of BAD with Bcl-X(L). The effect of EGF on phosphorylation of BADser112 was dependent on the action of p38 MAPK. We conclude that EGF signals via p38 MAPK to increase phosphorylation of BADser112 and thereby limit trophoblast apoptosis.

The IGF axis and placental function. a mini review

It is well known that the insulin-like growth factor (IGF) axis is an important regulator of foetal growth and in recent years, it has been suggested that the ligands IGF-I and IGF-II may, in part, mediate this effect by promoting proper placental development and function. In other tissues, IGF effects on metabolism, proliferation and differentiation are primarily mediated via IGF binding protein-regulated interaction of IGFs with the type 1 IGF receptor and therefore here, we review the placental expression and postulated role, of each of the IGF axis components and discuss the cellular mechanisms through which these effects are exerted.

Epidermal growth factor rescues trophoblast apoptosis induced by reactive oxygen species

Pre-eclampsia and intrauterine growth restriction are associated with increased apoptosis of placental villous trophoblast. This may result from placental hypoperfusion, leading to the generation of reactive oxygen species (ROS). Apoptosis can be induced in villous trophoblast following exposure to oxidative stress. Epidermal growth factor (EGF) reduces trophoblast apoptosis resulting from exposure to hypoxia. We hypothesised that exposure to hydrogen peroxide, a potent generator of ROS, would induce apoptosis in term placental villous explants and that this could be reduced by treatment with EGF. Placental explants were taken from normal term pregnancies and exposed to increasing doses of hydrogen peroxide (0-1,000 microM) or to a combination of increasing doses of hydrogen peroxide and EGF (0-100 ng/ml) for either 6 or 48 h. Apoptosis was assessed by TUNEL, proliferation by Ki-67 immunostaining, necrosis by lactate dehydrogenase activity and trophoblast differentiation by human chorionic gonadotrophin (hCG) secretion in conditioned culture media. Immunoperoxidase staining was performed to identify phosphorylated-AKT (p-AKT) and phosphorylated-PI3 kinase (p-PI3k). Exposure to 1,000 microM hydrogen peroxide for 48 h induced apoptosis in placental explants. The increase in TUNEL positive nuclei predominantly localised to syncytiotrophoblast. The amount of apoptosis was reduced to control levels by treatment with 10 and 100 ng/ml EGF. Proliferation of cytotrophoblasts within villous explants was significantly reduced following exposure to 1,000 microM hydrogen peroxide, this was restored to control levels by simultaneous treatment with 10 or 100 ng/ml EGF. Neither exposure to hydrogen peroxide or EGF altered the amount of necrosis. There was increased immunostaining for pPI3K following treatment with EGF. This study shows that apoptosis may be induced in villous trophoblast following exposure to ROS, and demonstrates the anti-apoptotic effect of EGF in trophoblast, the maintenance of which is essential for normal pregnancy.

Granulocyte-macrophage colony stimulating factor (GM-CSF) and co-culture can affect post-thaw development and apoptosis in cryopreserved embryos

PURPOSE

The objective of this study was to evaluate the effects of growth factor supplementation and Vero cell co-culture on apoptosis and development of frozen thawed one-cell mouse embryos.

METHODS

The following treatment regimens were assessed: (a) control medium (b) Vero cell co-culture and (c) growth factor supplemented medium. The individual growth factors tested were: GM-CSF, IGF-I, IGF-II, TNF-alpha, FGF-4, LIF, TGF-alpha, TGF-beta, IL-6, PDGF and EGF. Blastocyst development and differentiation were monitored. At termination of the experiments, overall blastomere number and apoptosis were assessed using the TUNEL assay.

RESULTS

No differences were observed in blastulation and hatching rates. ICM differentiation in thawed embryos was notably improved with either co-culture or growth factor supplementation. The only growth factor significantly modulating apoptosis in thawed embryos was granulocyte-macrophage colony stimulating factor (GM-CSF). GM-CSF enhanced continued cell survival and prevented apoptosis but did not influence overall cell number in developing blastocysts. Vero cell co-culture significantly increased cell number in blastocysts (124+/-42 vs 100+/-44 in control; P<0.05). Embryonic apoptosis was higher in the co-cultured embryos. The increased presence of apoptotic cells in blastocysts of high cell number may reflect the regulatory role of apoptosis in balancing ICM: TE ratios.

CONCLUSION

These data indicate that culture conditions can modulate post-thaw embryonic development and apoptosis.

Enhanced Basal Apoptosis in Cultured Term Human Cytotrophoblasts is Associated with a Higher Expression and Physical Interaction of p53 and Bak

We tested the hypothesis that the expression levels of p53 and the pro-apoptotic mediators from the Bcl-2 family are higher in cytotrophoblasts, when compared to cultures with abundant syncytiotrophoblasts. Cytotrophoblasts isolated from normal term human placentas were cultured in Dulbecco's Modified Eagle medium (DMEM) for 24 h, when the cytotrophoblast phenotype predominates, in DMEM for 72 h, when the syncytiotrophoblast phenotype predominates, or in Ham's-Waymouth medium or DMEM with 1.5% dimethylsulfoxide, each of which maintains the cytotrophoblast phenotype through 72 h of culture. Apoptosis was assessed by detection of cleavage products of poly-ADP-ribose polymerase, by expression of cleaved cytokeratin 18 intermediate filaments, and by assessment of caspase-3 activity. Independent of time in culture, cytotrophoblasts showed higher levels of apoptosis compared to syncytiotrophoblasts. Cytotrophoblasts also expressed a 2-fold higher level of p53, a 2-fold lower level of 60 kDa Mdm-2 protein, a 2-fold higher level of Bak, but no differences in the expression of 90 kDa Mdm-2, Bcl-2, Bcl-X(L), Mcl-1, Bax, Bad, and Bad phosphorylated at the serine(112), serine(136), or serine(155) sites, compared to the syncytiotrophoblasts. Using co-immunoprecipitation, we demonstrated a greater degree of Bak-p53 interaction in cytotrophoblasts than in syncytiotrophoblasts. We also detected Bak-Mcl-1 interaction that was no different between the two phenotypes. Among the proteins studied, enhanced p53 activity, differential Bak expression, and Bak-p53 interactions may contribute to the higher level of constitutive apoptosis in cultures of cytotrophoblasts compared to syncytiotrophoblasts.

Hypoxia regulates the expression of PHLDA2 in primary term human trophoblasts

Hypoxia influences gene expression in placental trophoblasts. We sought to examine the effect of hypoxia on trophoblast expression of human PHLDA2 (also termed IPL, TSSC3 or BWR-1C), a product of an imprinted gene on human chromosome 11p15.5 whose murine ortholog plays a pivotal role in placental development. We initially confirmed that PHLDA2 was expressed in term placental villi, primarily in the trophoblast layer. Using quantitative PCR we found that the expression of PHLDA2 gradually declined during differentiation of primary term human trophoblasts. A similar expression pattern was seen for p57(Kip2) and IGF-II, both products of imprinted genes on chromosome 11p15.5. Exposure of trophoblasts to hypoxia in vitro (O(2)<or=2%) markedly reduced the expression of PHLDA2 mRNA and protein. This effect was not consistent among other chromosome 11p15.5 genes products, as the expression of p57(Kip2) decreased, but that of IGF-II increased in hypoxic trophoblasts. PHLDA2 expression in trophoblasts exposed to TGFbeta1, -beta2 or -beta3 was unchanged. We conclude that hypoxia down-regulates the expression of PHLDA2 in human term placental trophoblasts. As murine PHLDA2 limits placental growth, our results suggest that down-regulation of PHLDA2 attenuates the impact of hypoxia on placental growth.

Human trophoblast survival at low oxygen concentrations requires metalloproteinase-mediated shedding of heparin-binding EGF-like growth factor

Heparin-binding EGF-like growth factor (HBEGF), which is expressed in the placenta during normal pregnancy, is down regulated in pre-eclampsia, a human pregnancy disorder associated with poor trophoblast differentiation and survival. This growth factor protects against apoptosis during stress, suggesting a role in trophoblast survival in the relatively low O(2) ( approximately 2%) environment of the first trimester conceptus. Using a well-characterized human first trimester cytotrophoblast cell line, we found that a 4-hour exposure to 2% O(2) upregulates HBEGF synthesis and secretion independently of an increase in its mRNA. Five other expressed members of the EGF family are largely unaffected. At 2% O(2), signaling via HER1 or HER4, known HBEGF receptors, is required for both HBEGF upregulation and protection against apoptosis. This positive-feedback loop is dependent on metalloproteinase-mediated cleavage and shedding of the HBEGF ectodomain. The restoration of trophoblast survival by the addition of soluble HBEGF in cultures exposed to low O(2) and metalloproteinase inhibitor suggests that the effects of HBEGF are mediated by autocrine/paracrine, rather than juxtacrine, signaling. Our results provide evidence that a post-transcriptional mechanism induced in trophoblasts by low O(2) rapidly amplifies HBEGF signaling to inhibit apoptosis. These findings have a high clinical significance, as the downregulation of HBEGF in pre-eclampsia is likely to be a contributing factor leading to the demise of trophoblasts.

The role of apoptosis in the regulation of trophoblast survival and differentiation during pregnancy

Apoptosis is important for normal placental development, but it may also be involved in the pathophysiology of pregnancy-related diseases. Normal placental development is dependent upon the differentiation and invasion of the trophoblast, the main cellular component of the placenta. Trophoblast apoptosis increases in normal placentas as gestation proceeds, and a greater incidence of trophoblast apoptosis has been observed in pregnancies complicated by preeclampsia or intrauterine growth retardation (IUGR). In response to different stimuli, apoptosis may be initiated extrinsically by the death receptor pathway or intrinsically by the mitochondrial pathway. The central executioners of apoptosis are the caspases, which cleave numerous vital cellular proteins to affect the apoptotic cascade. By inhibiting caspase activation, several endogenous inhibitors, including flice-like inhibitory proteins (FLIPs), inhibitors of apoptosis (IAPs), and antiapoptotic Bcl-2 family members, can prevent further propagation of the death signal. Macrophages present at the maternal-fetal interface may also contribute to trophoblast survival by removing apoptotic cells and producing cytokines and growth factors, which influence the progression of the apoptotic cascade. This review focuses on the role of apoptosis in trophoblast development and differentiation, the molecular mechanisms by which normal trophoblast apoptosis can occur, and how it is regulated to prevent excessive trophoblast apoptosis and possible pregnancy complications.

Multiple anti-apoptotic pathways stimulated by EGF in cytotrophoblasts

Epidermal growth factor (EGF) reduces apoptosis in primary cytotrophoblast (CT) in culture through two separate pathways: the extracellular signal related kinase (ERK) 1/2 and phosphatidyl inositol 3-kinase (PI-3 kinase) paths. Whether other pathways are involved in survival signalling is unknown. We here show that the c-Jun NH2 terminal kinase (JNK) and the mitogen activated kinase (MAPK) p38 are also activated by EGF as seen by increases in JNK and p38 phosphorylation. However, inhibition of JNK phosphorylation with the specific inhibitor SP600125 increases apoptosis in a manner refractory to the addition of EGF but inhibition of p38 phosphorylation with its specific inhibitor SB 203580 does not increase apoptosis. EGF also activates sphingosine kinase-1 (SPHK-1), which converts sphingosine to sphingosine-1-phosphate, and its inhibition with dimethyl sphingosine (DMS) increased trophoblast death. Inhibition of SPHK-1 also did not affect EGF stimulated phosphorylation of PI-3 kinase, Akt, ERK1/2 or p38 but inhibition of PI-3 kinase with a specific inhibitor LY294002 partly (40%) inhibited the EGF-stimulated increase in SPHK-1 activity. We conclude that, in addition to the PI-3 kinase and ERK1/2 pathways, EGF acts through its receptor to stimulate JNK, p38 and SPHK-1 pathways, but that the JNK and SPHK-1, and not the p38, pathways are involved in suppressing apoptosis. This information provides evidence that EGF stimulates survival along multiple pathways that differ in trophoblast and other cell types.

Epidermal growth factor stimulation of trophoblast differentiation requires MAPK11/14 (p38 MAP kinase) activation

Cultured human term villous cytotrophoblasts (CT) have been reported to be nonproliferating but differentiate when exposed to epidermal growth factor (EGF). Here we show that CT differentiate into chorionic gonadotropin (beta-hCG/CGB)-expressing cells when cultured with medium alone. The addition of EGF decreases CGB secretion and prolongs production for up to 13 days. EGF stimulates the phosphorylation (activation) of the signaling intermediate p38 (MAPK11/14), and blocking phosphorylation pharmacologically with either SB203580 or SB202190 strongly inhibited spontaneous and EGF-stimulated secretion of CGB. In addition, EGF-stimulated fusion of cytotrophoblasts into syncytial units was strongly inhibited by SB203580. EGF upregulated trophoblast proliferation (measured by bromodeoxyuridine uptake) and SB203580 increased this proliferation after 5 days. In agreement with these observations, EGF and SB203580 increased expression of the G1-phase-specific gene cyclin-D1 (CCND1) and SB203580 downmodulated its inhibitor p21 (CDKN1A). When added to villous explant cultures, EGF did nothing to the pattern of CGB secretion, but addition of SB203580 prevented the normal surge in secretion during syncytial regeneration over Days 3-7. These data support the hypothesis that EGF-stimulated cytotrophoblast differentiation to syncytium requires MAPK11/14 activation, and that cytotrophoblast proliferation can be stimulated in culture by EGF and enhanced by MAPK11/14 inhibition with a consequent reduction of differentiation.