Early Trophoblast Research Articles

HPV-16 exposed mouse embryos: a potential model for pregnancy wastage

Placentas from spontaneous abortions and preterm deliveries have a higher prevalence of Human papillomavirus (HPV) compared to placentas from elective abortions and term births. The objective was to determine the effects of HPV-16 on the adhesion and implantation properties of early embryo trophoblasts. Two-cell mouse embryos were cultured (medium G2, 5 % CO2, 37 °C) for 72-96 h and exposed to either HPV-16 rich SiHa cell lysates which were refrigerated after mechanical lysis, thawed lysates which had been frozen for freeze/thaw lysis method, or control medium, incubated (4-5 days) and evaluated by microscopy (N = 96 embryos, 3 repeated experiments). Trophoblasts were stained and images were digitized. Adhesion and dimension data were analyzed by Chi-square and t test, respectively. HPV-16 exposed embryos exhibited less adhesion through reduced implantation compared with the control (combined lysates 53.8 vs. 85.7 %, P < 0.05). Refrigerated and thawed lysate groups had similar reduced implantations (58.3 vs. 50.0 %). Of the embryos with implantation, 100 % in the refrigerated lysates were noted to have loose or abnormal adhesion. This was measured when embryos were noted to be lost after washes with HTF. There was no difference in trophoblast viability among the groups. Total trophoblast area was greater in the HPV-16 exposed frozen lysate group (1,881.8 ± 605.3 vs. control 848.8 ± 298.0 square units, mean ± SEM). HPV-16 inhibited trophoblasts adhesion needed for normal implantation, but not embryo development. Total trophoblast spread was increased after HPV-16 exposure suggesting that HPV-16 altered trophoblast migration. These results suggest that HPV-16 may induce abnormal placental growth resulting in pregnancy wastage.

Human pluripotent stem cells as alternative models to study trophoblast development

OPINION article Front. Physiol., 17 December 2013Sec. Craniofacial Biology and Dental Research https://doi.org/10.3389/fphys.2013.00374

Iodide transporters expression in early human invasive trophoblast

ContextThe placenta plays an essential role in the fetomaternal exchanges of iodine and thyroid hormones. Propylthiouracil (PTU) is presently considered to be the treatment of choice for hyperthyroidism during the first trimester of pregnancy. Little is known on the expression of iodide transporters in invasive human trophoblast and the possible effect of PTU on this early phase of human placental development. ObjectiveTo analyze during early pregnancy expression of sodium/iodide symporter (NIS) and pendrin at the feto–maternal interface in situ in first trimester placentas, in vitro during human trophoblastic cell differentiation in presence or not of PTU. DesignNIS and pendrin immunodetection were performed on 8–10 WG placental tissue sections and in primary cultures of first trimester placenta trophoblastic cells, which differentiate in vitro into syncytiotrophoblast or invasive extravillous cytotrophoblasts (EVCT). The effect of PTU (1 mM) was tested in EVCT on iodide transporters expression, cell invasion, and hCG secretion. ResultsNIS and pendrin were present in early human trophoblast at the maternofetal interface. Their expression was modulated with in vitro trophoblast differentiation. Early invasive EVCT were characterized by higher expression of NIS than pendrin. In vitro PTU did modify significantly neither EVCT iodide transporters expression nor EVCT biological functions: i.e. invasive properties and hCG secretion. ConclusionThis study reveals that NIS is highly expressed in early human trophoblast at the feto–maternal interface. PTU has no effect on early human trophoblast invasion.

Decreased expression of Gcm1 and its downstream targets Syncytin A and B is associated with severity of feto‐placental phenotypes in the BPH/5 model of preeclampsia (PE)

BPH/5 mice spontaneously develop the cardinal features of PE during pregnancy, including late gestational hypertension and proteinuria, along with fetoplacental abnormalities. We have utilized ultrasonography to categorize fetoplacental units (FPUs) at e10.5 into three increasingly severe phenotypic classes (I, II, and III). We tested the hypothesis that Gcm1, a key transcription factor in early trophoblast differentiation, and its downstream targets, Syncytin A and B, are dysregulated in BPH/5 FPUs at e10.5, and this is associated with phenotypic severity. Real‐time PCR revealed downregulation of each of these genes in compromised Class II and Class III BPH/5 FPUs vs C57 controls: Gcm1 (II= 0.3±0.16; III= 0.01±0.003 fold vs C57, n=3 p&lt;0.05), Syncytin A (II= 0.6±0.21, III= 0.05±0.008 fold vs C57, n=3 p&lt;0.05), and Syncytin B (II= 0.69±0.02, III= 0.30±0.14 fold vs C57, n=3 p&lt;0.05). In situ hybridization for Gcm1, Syncytin A and B confirmed this and localized downregulation to the developing labyrinth. Finally, Western analysis revealed decreased Gcm1 protein levels in BPH/5 Class I (29.1±14.3%, n=4, p&lt;0.01) and Class II (43.4±5.2%, n=4, p&lt;0.01) placentas vs C57 (n=6). This suggests that dysregulation of Gcm1 and its downstream targets Syncytin A and B may be involved in the abnormal labyrinth formation and fetoplacental demise observed in this model of PE. Funding: QNRF NPRP09‐1099‐279.

Galectin fingerprinting detects differences in expression profiles between bovine endometrium and placentomes as well as early and late gestational stages

The concept of a network within the family of adhesion/growth regulatory galectins implies distinct spatio-temporal expression profiles. To test this assumption immunohistochemically for bovine placenta, placentomal (P) and interplacentomal tissues (IP) were collected at a slaughterhouse from the three stages of pregnancy (early gestation = day 30–130; mid gestation = day 130–220; late gestation = day 220–275). The specimens were snap-frozen or fixed in Bouin’s solution, then embedded in paraffin. Gene expression for galectins-1, -3, -4 and -9 in P and IP of late gestational stages was monitored by RT-PCR. Galectin-type-specific antibodies were used for immunohistochemical localization. In IP, galectin-1 was present in stroma cells and early gestational trophoblast giant cells (TGC), whereas galectin-3 was confined to uterine epithelial cells. In contrast, both galectins were found in epithelia of P tissue. Uterine epithelial cells and blood vessel walls were positive for galectin-4, while galectin-9 was detected predominantly in uterine epithelial cells and late gestational TGC. Our study thus reveals individual profiles among the galectins tested, an indication for specific functions exerted by each protein in the bovine endometrium and placenta.

Matrix metalloproteinase-2 and -9 secretion by the human JAR choriocarcinoma cell line is stimulated by TNF-&amp;lt;i&amp;gt;α&amp;lt;/i&amp;gt;

The JAR choriocarcinoma cell line share many of the characteristics of early placental trophoblast cells including the invasion properties. Matrix metallo-proteinases (MMPs), the main actors of matrix proteolysis, are involved in normal invasion as well as in the invasive character of tumor cells and the metastase formation. Tumor necrosis factor-α (TNF-α) is present in the placental environment and TNF-α levels are elevated in some placental pathologies. In the present work, we addressed whether TNF-α is a modulator of JAR cell MMP secretion. Following TNF-α stimulation, zymographic analysis showed the increased secretion of the active form of MMP-2 and to a lesser extent proMMP-2 and MMP-9. In addition, MMP-2 gene expression only increased slightly whereas MMP-9 and TIMP-1 transcripts were undetectable. This suggests that TNF-α may modulate the secretion of MMPs independently of MMP gene expression control.

SATB Homeobox Proteins Regulate Trophoblast Stem Cell Renewal and Differentiation

The morphogenesis of the hemochorial placenta is dependent upon the precise expansion and differentiation of trophoblast stem (TS) cells. SATB homeobox 1 (SATB1) and SATB2 are related proteins that have been implicated as regulators of some stem cell populations. SATB1 is highly expressed in TS cells, which prompted an investigation of SATB1 and the related SATB2 as regulators of TS cells. SATB1 and SATB2 were highly expressed in rat TS cells maintained in the stem state and rapidly declined following induction of differentiation. SATB proteins were also present within the rat placenta during early stages of its morphogenesis and disappeared as gestation advanced. Silencing Satb1 or Satb2 expression decreased TS cell self-renewal and increased differentiation, whereas ectopic expression of SATB proteins promoted TS cell expansion and blunted differentiation. Eomes, a key transcriptional regulator of TS cells, was identified as a target for SATB proteins. SATB knockdown decreased Eomes transcript levels and promoter activity, whereas SATB ectopic expression increased Eomes transcript levels and promoter activity. Electrophoretic mobility shift assay as well as chromatin immunoprecipitation analyses demonstrated that SATB proteins physically associate with a regulatory site within the Eomes promoter. We conclude that SATB proteins promote TS cell renewal and inhibit differentiation. These actions are mediated in part by regulating the expression of the TS cell stem-associated transcription factor, EOMES.

The regulation of trophoblast migration across endothelial cells by low shear stress: consequences for vascular remodelling in pregnancy

In early human pregnancy placental trophoblasts migrate along uterine spiral arteries (SAs) and remodel these vessels into wide-bore conduits in a process essential for successful pregnancy. Until 10-12 weeks gestation trophoblasts plug spiral arteries, resulting in slow, high-resistance blood flow. This work examined the consequences of these low shear stress conditions on trophoblast migration, adhesion molecule expression, and attraction to chemotactic factors. Trophoblasts were cultured on fibronectin or human endothelial cells for 6-12 h under 0.5-6 dyne/cm(2) shear stress using the BioFlux200 system, and imaged by time-lapse microscopy. Computer-based imaging algorithms were developed to automatically quantify migration. Chemotaxis assays were run using parallel flow. Trophoblasts cultured on fibronectin or endothelial cells did not undergo directional migration in 0.5 and 2 dyne/cm(2) cultures; however, in 4 and 6 dyne/cm(2) trophoblasts migrated with the direction of flow (n= 4, P< 0.001). Shear stresses did not affect the speed of trophoblast migration, or adhesion molecule expression (E-selectin, α(4), β(1), and α(v)β(3) integrin). Trophoblasts cultured on endothelial cells migrated into media containing interleukin-8, macrophage chemoattractant protein-1, or Regulated-upon-Activation-Normal-T-cell-Expressed-and-Secreted (RANTES) (n= 5, P< 0.05). Shear stress increases trophoblast migration in the direction of flow, challenging the idea that trophoblasts migrate down spiral arteries retrograde to flow. This suggests that low shear stresses generated by trophoblast plugging of spiral arteries in the first trimester may favour arterial remodelling by preventing the migration with flow seen at higher shear stresses, allowing trophoblasts to migrate down the arteries in response to alternate stimuli such as uterine or endothelial cell-derived chemotactic factors.

Gelatin induces trophectoderm differentiation of mouse embryonic stem cells

In this study, we selected gelatin as ECM (extracellular matrix) to support differentiation of mES (mouse embryonic stem) cells into TE (trophectoderm), as gelatin was less expensive and widely used. We found that 0.2% and 1.5% gelatin were the suitable concentrations to induce TE differentiation by means of detecting Cdx2 expression using real-time PCR. Moreover, about 15% cells were positive for Cdx2 staining after 6 days differentiation. We discovered that the expressions of specific markers for TE, such as Cdx2, Eomes, Hand1 and Esx1 were prominently increased after gelatin induction. Meanwhile, the expression of Oct4 was significantly decreased. We also found that inhibition of the BMP (bone morphogenetic protein) signalling by Noggin could promote mES cells differentiation into TE, whereas inhibition of the Wnt signalling by Dkk1 had the contrary effect. This could be used as a tool to study the differentiation and function of early trophoblasts as well as further elucidating the molecular mechanism during abnormal placental development.

In-vitro effects of the antimicrobial peptide Ala8,13,18-magainin II amide on isolated human first trimester villous trophoblast cells

BackgroundResearch on antimicrobial cationic peptides (AMPs) has gained pace toward using their potential to replace conventional antibiotics. These peptides preferentially interact with negatively charged membrane lipids typically seen in bacteria and thereby lead to membrane perturbations and membrane dysfunction. However, one possible disadvantage of AMP drugs is their potential for toxicity, especially to those cells which display externalization of negatively charged moieties to the outer leaflet of the plasma membrane during the process of syncytialization. Human placental villous trophoblast is one such cell type. Indeed, intra-vaginal administration of an antimicrobial cationic peptide Ala8,13,18-magainin II amide (AMA) which is a synthetic analogue of magainin 2 derived from Xenopus frog has been observed to result in inhibition of pregnancy establishment in monkeys. However, only little is known about the cellular behavior of early placental cytotrophoblasts (CTB) in the presence of cationic antimicrobial peptides. It is believed that suitable cell culture approaches using AMA as a representative alpha-helical AMP may yield tangible knowledge in this regard.MethodsImmunocytochemical (ICC) analyses using confocal microscopy (n = 6 for each treatment sub-group) and Western blot (WB) method (n = 5 for each treatment sub-group) of CTB differentiation based on synthesis of beta-hCG and hPL, and apoptosis based on apoptosis-associated cytokeratin 18 neo-epitope (CK18f) were performed for CTB isolated from human first trimester placental villi and grown in serum-free primary culture for 24 h, 48 h and 96 h on rat-tail collagen with and without AMA (1000 ng/ml). Moreover, secretion of beta-hCG and hPL into conditioned media from isolated CTB grown in vitro for 24 h, 48 h and 96 h (n = 6/each sub-group) with and without AMA was examined using enzyme immunoassays. Furthermore, TUNEL assay, and cell viability based on LDH leakage into medium (n = 6/each sub-group) were assessed to examine the phenomenon of cell death with time and administration of AMA.ResultsCTB in serum-free primary culture showed increased (P < 0.05) level of synthesis and secretion of beta-hCG and hPL with time, and higher (P < 0.05) level of cellular cytokeratin 18 neo-epitope and number of TUNEL-positive cells, and LDH activity in conditioned medium at 96 h of culture. Exposure of CTB to AMA resulted in lower (P < 0.05) level of synthesis and secretion of beta-hCG and hPL, as well as, an increase (P < 0.05) of cellular cytokeratin 18 neo-epitope and number of TUNEL-positive cells, and LDH activity in conditioned medium at 96 h as compared to the control treatment.ConclusionsAdministration of AMA resulted in attenuation of differentiation, enhancement in apoptosis and loss of viability in early placental villi trophoblast cells in primary culture. Thus, it appears that administration of alpha-helical AMP may adversely affect the process of placentation and pregnancy outcome.

IGF2, IGF binding protein 1, and matrix metalloproteinases 2 and 9 in implantation-stage endometrium following immunoneutralization of vascular endothelial growth factor in the rhesus monkey

Blastocyst implantation in the rhesus monkey is inhibited by administration of antibody against vascular endothelial growth factor (VEGF) A during peri-implantation period with no change in the circulatory concentrations of estradiol, progesterone, and VEGF. In this study, we have investigated the effect of administration of a MAB to VEGFA on days 5 and 10 after ovulation upon the mRNA expression, immunopositive protein expression, and immunohistological localization of IGF2, IGF binding protein 1 (IGFBP1) and matrix metalloproteinases (MMPs) 2 and 9 in the implantation-stage endometrium collected on day 13 after ovulation from fecund cycles of rhesus monkeys. The comparison between isotype-matched IgG (control; n=8)- and VEGF antibody (VEGF Mab; n=8)-treated animals revealed higher (P<0.05) IGF2 in lacunar and villous syncytiotrophoblasts, trophoblast cell columns, migrating extravillous trophoblast cells, and endovascular trophoblast cells in control animals, but with no change in the various cell types of maternal endometrium between the two groups. No change in IGFBP1 expression in the endometrium was observed between the two groups. MMPs 2 and 9 were detected in syncytiotrophoblast in lacunae and villi, trophoblast cell columns, and extravillous trophoblast cells in control samples. MMP9 transcript expression in maternal endometrium and its immunopositivity in endometrial stroma and trophoblast cells were lower (P<0.05) with no change in MMP2 level in VEGF Mab-exposed samples compared with those in control samples. A functional network involving VEGF, IGF2, and MMP9 in early placental trophoblast cells and maternal endometrium appears to be important for normal placentation.

Characterization of invasive trophoblasts generated from human embryonic stem cells

Abnormal human embryo implantation leads to poor foetal development and miscarriage, or pre-eclampsia. Ethical and practical considerations concerning implantation limit its investigation, and it is often difficult to extrapolate findings in laboratory animals when implantation processes show diverse species differences. Therefore, it is important to develop new in vitro models to study the earliest events of human implantation. The aim of this study was to derive trophoblast cell lines from human embryonic stem cells (hESCs) by a robust protocol and co-culture of these cells with an established endometrial cell culture system to validate a model of trophoblast invasion at implantation. Derivation of trophoblast cell lines from hESC lines was established by spontaneous and induced differentiation of embryoid bodies and by initial measurement of hCGβ secretion by enzyme-linked immunosorbent assay and their phenotype investigated using gene- and protein-expression markers. Vesicles formed from an aggregating trophoblast were co-cultured with decidualized human endometrial stromal cells in hypoxic (2% oxygen) and normoxic (20% oxygen) environments. Derived villous cytotrophoblast cell (CTB) lines further differentiated to invasive, extra-villous CTBs. Eventually, cells lost their proliferative capacity, with some lines acquiring karyotypic changes, such as a gain in the X chromosome. Cell-invasion assays confirmed that the extra-villous CTBs were invasive and erosion of the endometrial stromal layer occurred, particularly under hypoxic conditions in vitro. Trophoblast cell lines derived from hESCs differentiate and adapt in vitro and can be used as a model to study the mechanisms of early trophoblast invasion.

Regulation of early trophoblast differentiation – Lessons from the mouse

The earliest stages of trophoblast differentiation are of tremendous importance to mediate implantation and to lay the anatomical foundations for normal placental development and function throughout gestation. Yet our molecular insights into these early developmental processes in humans have been limited by the inaccessibility of material and the unavailability of trophoblast cell lines that fully recapitulate the behaviour of early placental trophoblast. In this review we highlight recent advances that have come from the study of distinct stem cell types representative of the embryonic and extraembryonic lineages in the mouse, and from the study of mouse mutants. These models have revealed the presence of intricate transcriptional networks that are set up by signalling pathways, translating extracellular growth factor and cell positional information into distinct lineage-specific transcriptional programmes. The trophoblast specificity of these networks is ensured by epigenetic mechanisms including DNA methylation and histone modifications that complement each other to define trophoblast cell fate and differentiation. Despite the anatomical differences between mouse and human placentas, it seems that important aspects of early trophoblast specification are conserved between both species. Thus we may be able to build on our insights from the mouse to better understand early trophoblast differentiation in the human conceptus which is important for improving assisted reproductive technologies and may enable us in the future to derive human trophoblast stem cell lines. These advances will facilitate the investigation of genetic, epigenetic and environmental influences on early trophoblast differentiation in normal as well as in pathological conditions.

Wnt Signalling in Implantation, Decidualisation and Placental Differentiation – Review

The family of secreted Wingless ligands plays major roles in embryonic development, stem cell maintenance, differentiation and tissue homeostasis. Accumulating evidence suggests that the canonical Wnt pathway involving nuclear recruitment of β-catenin and activation of Wnt-dependent transcription factors is also critically involved in development and differentiation of the diverse reproductive tissues. Here, we summarise our present knowledge about expression, regulation and function of Wnt ligands and their frizzled receptors in murine and human endometrial and placental cell types. In mice, Wnt signalling promotes early trophoblast lineage development, blastocyst activation, implantation and chorion–allantois fusion. Moreover, different Wnt ligands play essential roles in the development of the murine uterine tract, in cycling endometrial cells and during decidualisation. In humans, estrogen-dependent endometrial cell proliferation, decidualisation, trophoblast attachment and invasion were shown to be controlled by the particular signalling pathway. Failures in Wnt signalling are associated with infertility, endometriosis, endometrial cancer and gestational diseases such as complete mole placentae and choriocarcinomas. However, our present knowledge is still scarce due to the complexity of the Wnt network involving numerous ligands, receptors and non-canonical pathways. Hence, much remains to be learned about the role of different Wnt signalling cascades in reproductive cell types and their changes under pathological conditions.

Ischemia-modified albumin and cardiovascular risk markers in polycystic ovary syndrome with or without insulin resistance

The aim of this study was to evaluate ischemia-modified albumin levels (IMA) in polycystic ovary syndrome (PCOS) cases with and without insulin resistance and the correlation of IMA with carotid intima media thickness, homocysteine, and high-sensitivity C-reactive protein levels. Significantly higher levels of IMA in young lean PCOS cases, more relevant in insulin resistant cases, indicates chronic hypoxia and oxidative stress which might play a role in the metabolic consequences in PCOS.

Hyperglycosylated hCG Is a Marker of Early Human Trophoblast Invasion

Human chorionic gonadotropin (hCG) is the major pregnancy glycoprotein hormone whose maternal concentration and glycan structure change all along pregnancy. hCG is mainly secreted by the syncytiotrophoblast covering the chorionic villi, but little is known about the source of hyperglycosylated hCG (hCG-H) production. The objective of the study was to analyze expression and secretion of hCG and hCG-H in vitro during human trophoblastic cell differentiation, in situ in first-trimester placentas, and in maternal sera during early pregnancy. hCG and hCG-H were measured in cell supernatants from primary cultures of first-trimester placenta trophoblastic cells, which differentiate in vitro into syncytiotrophoblast or invasive extravillous cytotrophoblasts (evct). hCG-H immunodetection were performed on 9 wk gestation (WG) placental tissue sections. Total hCG and hCG-H were quantified by chemiluminometric assay in 539 maternal sera collected between 9 and 19 WG during normal pregnancies. In vitro, hCG secretion reached 37 ng/ml per μg DNA during syncytiotrophoblast formation but contained few hCG-H (2-5% of total hCG). In contrast, hCG secretion (20 ng/ml per μg DNA) in evct supernatants contained 10-20% hCG-H. In situ, hCG-H immunostaining was strong in invasive and endovascular evct, weaker in mononucleated villous cytotrophoblasts, but negative in the syncytiotrophoblast. In maternal sera, hCG-H concentrations continuously decreased during pregnancy from 406 ± 222 ng/ml at 9 WG to 8 ± 6 ng/ml at 19 WG, whereas total hCG picked up at 11 WG and then decreased. This study suggests that the high levels of hCG-H observed in first-trimester maternal sera are mainly from invasive evct origin, reflecting the early trophoblast invasion process.

Immunoregulation in normal pregnancy and pre-eclampsia: an overview.

Pre-eclampsia is a major disorder of human pregnancy, which may have an immunological basis. It is a disease of two stages. The first stage concerns the relative failure of early trophoblast invasion and remodelling of the spiral arteries, leading to a poor blood supply to the placenta, exposing it to oxidative stress. The inadequate trophoblast invasion may result from decreased expression of human leukocyte antigen-G (HLA-G) leading to an abnormal interaction with decidual natural killer (NK) cells, which are believed to play a major role in these processes through the production of immunoregulatory cytokines and angiogenic factors. Recent evidence suggests that the interaction between trophoblast human leukocyte antigen-C (HLA-C) molecules and decidual NK cell receptors may be the point at which the apparent partner specificity of the disease originates. The second stage is the maternal syndrome, which is characterized by a generalized systemic inflammatory response involving both leukocytes and endothelium. The inflammatory stimulus is believed to come from the placenta. In pre-eclampsia, placental oxidative stress may lead to increased shedding of apoptotic and/or necrotic syncytiotrophoblast debris into the maternal circulation. There is evidence that such trophoblast debris interacts with maternal leukocytes and endothelial cells to stimulate the release of proinflammatory cytokines, which could then trigger the maternal disease.

ELF5-enforced transcriptional networks define an epigenetically regulated trophoblast stem cell compartment in the human placenta.

The first definitive cell fate decision in development occurs at the blastocyst stage with establishment of the trophoblast and embryonic cell lineages. In the mouse, lineage commitment is achieved by epigenetic regulation of a critical gatekeeper gene, the transcription factor Elf5, that reinforces placental cell fate and is necessary for trophoblast stem (TS) cell self-renewal. In humans, however, the epigenetic lineage boundary seems to be less stringent since human embryonic stem (ES) cells, unlike their murine counterparts, harbour some potential to differentiate into trophoblast derivatives. Here, we show that ELF5 is expressed in the human placenta in villous cytotrophoblast cells but not in post-mitotic syncytiotrophoblast and invasive extravillous cytotrophoblast cells. ELF5 establishes a circuit of mutually interacting transcription factors with CDX2 and EOMES, and the highly proliferative ELF5(+)/CDX2(+) double-positive subset of cytotrophoblast cells demarcates a putative TS cell compartment in the early human placenta. In contrast to placental trophoblast, however, ELF5 is hypermethylated and largely repressed in human ES cells and derived trophoblast cell lines, as well as in induced pluripotent stem cells and murine epiblast stem cells. Thus, these cells exhibit an embryonic lineage-specific epigenetic signature and do not undergo an epigenetic reprogramming to reflect the trophoblast lineage at key loci such as ELF5. Our identification of the trophoblast-specific transcriptional circuit established by ELF5 will be instrumental to derive human TS cell lines that truly reflect early placental trophoblast and that will be most beneficial to gain insights into the aetiology of common pregnancy complications, including intra-uterine growth restriction and pre-eclampsia.

311. REGULATION OF THE RENIN ANGIOTENSIN SYSTEM (RAS) IN A TROPHOBLAST CELL LINE BY CYCLIC ADENOSINE MONOPHOSPHATE (cAMP) AND 5'-AZA-2'-DEOXYCYTIDINE (AZA)

Renin and renin-like activities have been detected in early gestation placentae1,2. To explore what regulates RAS expression in trophoblasts we studied the effects of cAMP and AZA (DNA demethylating agent) on the expression of mRNAs for prorenin receptor (ATP6AP2), prorenin (REN), angiotensinogen (AGT), angiotensin converting enzyme (ACE), ACE2, angiotensin II type 1 receptor (AGTR1), and a downstream target of the prorenin receptor, cyclooxygenase-2 (PTGS2) in the early human trophoblast cell line HTR-8/SVneo. Cells were cultured for 24 or 48 h with vehicle, 0.5 mM cAMP or 15 mM AZA. Messenger RNA abundances were measured relative to Alien RNA using real-time qRT-PCR. All mRNAs were detected except for ACE and ACE2. REN mRNA abundance was increased by cAMP and AZA (P &lt; 0.0001). However, cAMP was more effective than AZA at both 24 and 48 h (P &lt; 0.0001; P &lt; 0.05) at the concentrations employed. AZA significantly increased AGT mRNA levels at 24 h (P = 0.001) and AGTR1 mRNA levels at 48 h (P &lt; 0.0001), while cAMP had no effect. P TGS2 mRNA expression was increased by cAMP at 24 h (P &lt; 0.0001) and by AZA at 48 h (P &lt; 0.0001). cAMP and AZA had no effect on ATP6AP2 abundance. Thus, prorenin may function directly through the prorenin receptor, since cAMP upregulated both REN and its downstream target PTGS2 in HTR-8/SVneo cells, especially considering that ACE and ACE2 were not expressed. Our findings also suggest that expression of the RAS in trophoblast is regulated by DNA methylation as there was sustained over expression of REN, AGT, AGTR1 and PTGS2 with AZA. The ATP6AP2 promoter possesses CpG islands; however, its expression was not affected by AZA. This may suggest that either DNA methylation is not involved in the regulation of this gene, or that the over expressed prorenin binding to its receptor is causing suppression of ATP6AP2 abundance via a previously identified negative feedback pathway. (1) Pringle et al., Perinatal Society of Australia &amp; New Zealand (PSANZ) 2010, Wellington, New Zealand (Abstract).(2) Itskovitz et al., Journal of Clinical Endocrinology and Metabolism, 1992, 75: 906–10.

Activation of Peroxisome Proliferator-Activated Receptor Gamma by Human Cytomegalovirus for De Novo Replication Impairs Migration and Invasiveness of Cytotrophoblasts from Early Placentas

Human cytomegalovirus (HCMV) contributes to pathogenic processes in immunosuppressed individuals, in fetuses, and in neonates. In the present report, by using reporter gene activation assays and confocal microscopy in the presence of a specific antagonist, we show for the first time that HCMV infection induces peroxisome proliferator-activated receptor gamma (PPARgamma) transcriptional activity in infected cells. We demonstrate that the PPARgamma antagonist dramatically impairs virus production and that the major immediate-early promoter contains PPAR response elements able to bind PPARgamma, as assessed by electrophoretic mobility shift and chromatin immunoprecipitation assays. Due to the key role of PPARgamma in placentation and its specific trophoblast expression within the human placenta, we then provided evidence that by activating PPARgamma human cytomegalovirus dramatically impaired early human trophoblast migration and invasiveness, as assessed by using well-established in vitro models of invasive trophoblast, i.e., primary cultures of extravillous cytotrophoblasts (EVCT) isolated from first-trimester placentas and the EVCT-derived cell line HIPEC. Our data provide new clues to explain how early infection during pregnancy could impair implantation and placentation and therefore embryonic development.