Epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor localization in the baboon (Papio anubis) uterus during the menstrual cycle and early pregnancy

Cytotrophoblast, Not Syncytiotrophoblast, Dominates Glycolysis and Oxidative Phosphorylation in Human Term Placenta

The syncytiotrophoblast (SCT) at the maternal-fetal interface has been presumed to be the primary driver of placental metabolism, and the underlying progenitor cytotrophoblast cells (CTB) an insignificant contributor to placental metabolic activity. However, we now show that the metabolic rate of CTB is much greater than the SCT. The oxygen consumption and extracellular acidification rate, a measure of glycolysis, are both greater in CTB than in SCT in vitro (CTB: 96 ± 16 vs SCT: 46 ± 14 pmol O₂ × min⁻¹ × 100 ng DNA⁻¹, p < 0.001) and (CTB: 43 ± 6.7 vs SCT 1.4 ± 1.0 ∆mpH × min⁻¹ × 100 ng DNA⁻¹, p < 0.0001). Mitochondrial activity, as determined by using the mitochondrial activity-dependent dye Mitotracker CM-H₂TMRosa, is higher in CTB than in SCT in culture and living explants. These data cast doubt on the previous supposition that the metabolic rate of the placenta is dominated by the SCT contribution. Moreover, differentiation into SCT leads to metabolic suppression. The normal suppression of metabolic activity during CTB differentiation to SCT is prevented with a p38 MAPK signaling inhibitor and epidermal growth factor co-treatment. We conclude that the undifferentiated CTB, in contrast to the SCT, is highly metabolically active, has a high level of fuel flexibility, and contributes substantially to global metabolism in the late gestation human placenta.

Epidermal growth factor stimulates proliferation and migration of porcine trophectoderm cells through protooncogenic protein kinase 1 and extracellular-signal-regulated kinases 1/2 mitogen-activated protein kinase signal transduction cascades during early pregnancy

For successful implantation and establishment of early epitheliochorial placentation, porcine conceptuses require histotroph, including nutrients and growth factors, secreted by or transported into the lumen of the uterus. Epidermal growth factor (EGF), an essential component of histotroph, is known to have potential growth-promoting activities on the conceptus and uterine endometrium. However, little is known about its effects to transactivate cell signaling cascades responsible for proliferation, growth and differentiation of conceptus trophectoderm. In the present study, therefore, we determined that EGFR mRNA and protein were abundant in endometrial luminal and glandular epithelia, stratum compactum stroma and conceptus trophectoderm on days 13-14 of pregnancy, but not in any other cells of the uterus or conceptus. In addition, primary porcine trophectoderm (pTr) cells treated with EGF exhibited increased abundance of phosphorylated (p)-AKT1, p-ERK1/2 MAPK and p-P90RSK over basal levels within 5min, and effect that was maintained to between 30 and 120min. Immunofluorescence microscopy revealed abundant amounts of p-ERK1/2 MAPK and p-AKT1 proteins in the nucleus and, to a lesser extent, in the cytoplasm of pTr cells treated with EGF as compared to control cells. Furthermore, the abundance of p-AKT1 and p-ERK1/2 MAPK proteins was inhibited in control and EGF-treated pTr cells transfected with EGFR siRNA. Compared to the control siRNA transfected pTr cells, pTr cells transfected with EGFR siRNA exhibited an increase in expression of IFND and TGFB1, but there was no effect of expression of IFNG. Further, EGF stimulated proliferation and migration of pTr cells through activation of the PI3K-AKT1 and ERK1/2 MAPK-P90RSK cell signaling pathways. Collectively, these results support the hypothesis that EGF coordinately activates multiple cell signaling pathways critical to proliferation, migration and survival of trophectoderm cells that are critical to development of porcine conceptuses during implantation and placentation.

Peak serum estradiol level during controlled ovarian hyperstimulation is associated with increased risk of small for gestational age and preeclampsia in singleton pregnancies after in vitro fertilization

OBJECTIVE

To assess the impact of elevated peak serum E(2) levels (EPE(2); defined as levels >90th percentile) on the day of hCG administration during controlled ovarian hyperstimulation (COH) for IVF on the likelihood for small for gestational age (SGA), preeclampsia (PreE), and preterm delivery (PTD) in singleton pregnancies.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care academic medical center.

PATIENT(S)

Singleton live-birth pregnancies conceived after fresh IVF-ET.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The delivery rate of SGA infants and the development of PreE and PTD in patients with and without EPE(2).

RESULT(S)

Patients with EPE(2) during COH were more likely to deliver SGA infants (7 [26.9%] vs. 10 [3.8%]; odds ratio [OR], 95% confidence interval [CI] {9.40, 3.22-27.46}) and develop PreE (5 [18.5%] vs. 12 [4.5%]; adjusted OR, 95% CI {4.79, 1.55-14.84}). No association was found between EPE(2) and the likelihood for delivery before 37 weeks, 35 weeks, or 32 weeks of gestation. Receiver operating characteristic analysis revealed that EPE(2) level predicted adverse obstetrical outcome (SGA + PreE) with 38.5% and 91.7% sensitivity and specificity, respectively. Using a serum peak E(2) cutoff value of 3,450 pg/mL (>90th percentile level), the positive predictive value was 37%, while the negative predictive value was 92%.

CONCLUSION(S)

EPE(2) level (>3,450 pg/mL) on the day of hCG administration during COH is associated with greater odds of developing PreE and delivery of an SGA infant in singleton pregnancies resulting from IVF cycles.

Ovarian stimulation and low birth weight in newborns conceived through in vitro fertilization

OBJECTIVE

Singleton neonates born after in vitro fertilization (IVF) are at increased risk for low birth weight, preterm delivery, or both. We sought to assess whether the alteration of the peri-implantation maternal environment resulting from ovarian stimulation may contribute to increased risk of low birth weight in IVF births.

METHODS

The Society for Assisted Reproductive Technologies database was used to identify IVF-conceived neonates born in the United States between 2004 and 2006. Associations were assessed in neonates born after fresh compared with frozen and thawed embryo transfer in women of similar ovarian responsiveness, in paired analysis of neonates born to the same woman after both types of embryo transfer, and in neonates born after oocyte donation.

RESULTS

Of 56,792 neonates identified, 38,626 and 18,166 were conceived after transfer of fresh and frozen embryos, respectively. In singletons, there was no difference in preterm delivery. However, the odds of overall low birth weight (10% compared with 7.2%; adjusted odds ratio [OR] 1.35; 95% confidence interval [CI] 1.20-1.51), low birth weight at term (2.5% compared with 1.2%, adjusted OR 1.73, 95% CI 1.31-2.29), and preterm low birth weight (34.1% compared with 23.8%, adjusted OR 1.49, 95% CI 1.24-1.78) were all significantly higher after fresh embryo transfer. In singletons, after either fresh or frozen embryo transfer in the same patient, this association was even stronger (low birth weight: 11.5% compared with 5.6%, adjusted OR 4.66, 95% CI 1.18-18.38). In oocyte donor recipients who do not undergo any ovarian hormonal stimulation for either a fresh or a frozen embryo transfer, no difference in low birth weight was demonstrated (11.5% compared with 11.3% adjusted OR 0.99, 95% CI 0.82-1.18).

CONCLUSION

The ovarian stimulation-induced maternal environment appears to represent an independent mediator contributing to the risk of low birth weight, but not preterm delivery, in neonates conceived after IVF.

LEVEL OF EVIDENCE

II.

Epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor expression and localization in the canine endometrium during the estrous cycle and in bitches with pyometra

Gene expression and immunohistochemical localization of epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGF-R) were compared between the endometrium of bitches (Canis familiaris) with pyometra accompanied by cystic endometrial hyperplasia (CEH) and that of healthy bitches at similar stages of the estrous cycle. In normal bitches, endometrial TGF-alpha mRNA levels were highest at proestrus and gradually decreased as the cycle progressed to anestrus. Epidermal growth factor receptor mRNA levels were not significantly affected by the stage of the estrous cycle. Epidermal growth factor mRNA levels were higher at Day 35 of diestrus than at other stages of the estrous cycle (P<0.05). In bitches with pyometra, endometrial TGF-alpha and EGF-R mRNA levels did not differ significantly from those at diestrus in normal bitches, but EGF mRNA levels were lower than those at Day 35 of diestrus in normal bitches (P<0.05). In normal bitches, positive immunohistochemical staining for TGF-alpha, EGF, and EGF-R was mainly present in the glandular and luminal epithelial cells of the endometrium. In contrast, in bitches with pyometra, immunoreactivity for EGF was clearly present in endometrial stromal cells. Inflammatory cells that had infiltrated the endometrial stroma stained strongly for TGF-alpha and EGF-R. Luminal and glandular epithelial cells also stained positive for EGF-R. In conclusion, expression of TGF-alpha by inflammatory cells and a low level of expression and differential localization of EGF may be involved in aberrant growth of endometrial glands and development of CEH.

Defective implantation and placentation: laying the blueprint for pregnancy complications

Normal implantation and placentation is critical for pregnancy success. Many pregnancy-related complications that present late in gestation (such as pre-eclampsia and preterm labour) appear to have their origins early in pregnancy with abnormalities in implantation and placental development. Implantation is characterized by invasion of the maternal tissues of the uterus by fetal trophoblast, and the degree to which trophoblast invades these tissues appears to be a major determinant of pregnancy outcome. Excessive invasion can lead to abnormally firm attachment of the placenta to the myometrium (placenta accreta) with increased maternal and perinatal morbidity. Inadequate invasion, specifically restricted endovascular invasion, has been implicated in the pathophysiology of such conditions as pre-eclampsia (gestational proteinuric hypertension), preterm premature rupture of membranes, preterm labour, and intrauterine growth restriction. The molecular and cellular mechanisms responsible for implantation remain enigmatic. This review will include an overview of implantation followed by a discussion of a number of molecular mechanisms implicated in defective implantation and placentation including the role of decidual prostaglandins and haemorrhage in regulating trophoblast invasion. An improved understanding of the molecular mechanisms responsible for abnormal implantation and placentation will likely improve clinicians' abilities to treat disorders that occur along this continuum, including infertility, recurrent pregnancy loss, pre-eclampsia, and preterm birth.

Effect of epidermal growth factor in preimplantation development of porcine cloned embryos

In this study, we determined the expression of epidermal growth factor (EGF) and its receptor (EGFr) gene, and the effect of exogenous EGF supplementation on preimplantation development of porcine somatic cell nuclear transfer (SCNT) embryos. In vitro matured gilt oocytes were fertilized with frozen-thawed semen in vitro or reconstructed with fetal fibroblasts by SCNT. In Experiment 1, total RNA was isolated from oocytes, preimplantation SCNT, or in vitro fertilization (IVF) embryos. The expression of EGF and EGFr mRNA was determined using reverse transcription-polymerase chain reaction (RT-PCR). In SCNT and IVF embryos, the EGF mRNA was detected in oocytes, 2-cell, 4-cell, 8-cell, morulae, and blastocysts, while EGFr mRNA was detected in oocytes, 2-cell, morulae, and blastocysts. In Experiment 2, SCNT embryos at 1-cell stage were cultured in North Carolina State University (NCSU)-23 medium supplemented with different concentrations of EGF (0.1, 1, or 10 ng/ml). Supplementing with 10 ng/ml EGF improved cleavage rate (82.8% vs. 76.8%, P<0.05), but not the rate of blastocyst formation compared to the control. At all concentrations, EGF increased (P<0.05) the total cell number in blastocysts (range 50.5-53.7 vs. 43.9). In Experiment 3, EGF (10 ng/ml) was added to NCSU-23 medium at the morula stage. The EGF did not affect blastocyst formation, total cell number in blastocysts or the ratio of inner cell mass (ICM) to total cell number. In conclusion, we demonstrated that EGF and EGFr mRNA are expressed in porcine IVF and SCNT preimplantation embryos, and that EGF increased the quality of blastocysts by increasing total cell numbers in porcine SCNT embryos.

Immunocytochemical localization of epidermal growth factor receptor in early embryos of the Japanese medaka fish (Oryzias latipes)

This study was undertaken to localize epidermal growth factor receptor (EGFR) during early development of Japanese medaka embryos using immunocytochemistry. Specific staining was observed in all stages studied. All of the cells of the embryonic disc from the germinal disc (1 cell) through the late high blastula stages stained moderately for EGFR. Beginning with the flat blastula stage, the surface and lateral cells of the embryonic disc and the cells migrating around the yolk stained intensely for EGFR, and this continued throughout the study period. The presence of the keel at the late gastrula stage did not affect the moderate staining of the majority of the embryonic disc cells. When somites first appeared, the keel region stained less intensely than before, but scattered individual cells stained intensely for EGFR. Embryos with 12 somites had a neural tube that was lightly stained except for a few intensely stained individual cells. The neural tube, notochord and somites in 24-somite embryos lacked immunostaining. However, the surface epithelium, aorta, intestinal epithelium and pronephric duct demonstrated EGFR immunostaining. This study demonstrates that EGFR is present during medaka development and supports the hypothesis that EGFR ligands are important during cleavage, gastrulation and early organogenesis.

Regulation of plasminogen activator inhibitor 1 expression by interaction of epidermal growth factor with progestin during decidualization of human endometrial stromal cells

OBJECTIVE

During human pregnancy implantation, trophoblasts invade maternal blood vessels in a process that risks hemorrhage. Previous studies have demonstrated enhanced expression of type 1 plasminogen activator inhibitor, the primary inhibitor of fibrinolysis, during progestin-induced decidualization of estradiol-primed human endometrial stromal cells in vivo and in vitro. Decidual cell-expressed plasminogen activator inhibitor 1 is appropriately positioned to avert implantational hemorrhage. Because of the absence of estrogen or progesterone response elements from the plasminogen activator inhibitor 1 gene promoter, I posited that epidermal growth factor mediates these steroid effects and that expression of epidermal growth factor receptor in human endometrial stromal cells is under ovarian steroid control.

STUDY DESIGN

Confluent human endometrial stromal cells were exposed to vehicle control or to either estradiol (10(-8) mol/L) or medroxyprogesterone acetate (10(-7) mol/L), or both, with or without growth factors. After 40 hours the cultures were analyzed for plasminogen activator inhibitor 1 protein and messenger ribonucleic acid expressions. Immunostaining for epidermal growth factor receptor was carried out in sections of cycling and gestational endometrial tissues.

RESULTS

In the absence of steroids, epidermal growth factor did not alter plasminogen activator inhibitor 1 expression. In the absence of epidermal growth factor, estradiol and medroxyprogesterone acetate enhanced human endometrial stromal cell-secreted plasminogen activator inhibitor 1 protein levels 8-fold (n = 12; P <.001), whereas estradiol alone had no effect. Marked synergistic increases in plasminogen activator inhibitor 1 levels were elicited when epidermal growth factor was added with estradiol and medroxyprogesterone acetate (n = 12; 65-fold; P <.0001). Both transforming growth factor alpha and epidermal growth factor, which act through epidermal growth factor receptor, increased steady-state plasminogen activator inhibitor 1 messenger ribonucleic acid levels several-fold when added with estradiol and medroxyprogesterone acetate. In contrast, transforming growth factor beta, which does not activate epidermal growth factor receptor, did not elevate plasminogen activator inhibitor 1 messenger ribonucleic acid or protein levels whether added alone or with estradiol and medroxyprogesterone acetate. In correspondence with these in vitro observations, immunostaining for epidermal growth factor receptor was increased in human endometrial stromal cells undergoing decidualization in sections of secretory phase and first-trimester endometrial tissue.

CONCLUSIONS

Taken together, these in vitro and in vivo results indicate that both epidermal growth factor and progesterone receptors are required for maximal plasminogen activator inhibitor 1 expression by human endometrial stromal cells.

Epidermal growth factor family in rhesus monkey uterus during the menstrual cycle and early pregnancy

This study examines immunohistochemically the presence of EGF, TGFalpha, HB-EGF, AR, and EGFR, members of the EGF family in the monkey uterus during the menstrual cycle and early pregnancy. EGF, TGFalpha, HB-EGF, AR, and EGFR were mainly localized in glandular and luminal epithelium. TGFalpha, HB-EGF, and AR staining were stronger in the glandular epithelium closer to the myometrium than in that closer to the luminal epithelium. The level of EGF, TGFalpha, HB-EGF, AR, and EGFR staining was low on days 1 and 6, and began to increase on day 9 of the menstrual cycle. A high level of EGF, and EGFR staining was maintained on days 16, 20, and 25 of the menstrual cycle. The highest levels of TGFalpha, AR, and HB-EGF staining were seen on days 16 and 20 of the menstrual cycle. In early pregnancy, a low level of EGF, TGFalpha, HB-EGF, AR, and EGFR staining appeared on days 1 and 2 of pregnancy, and then gradually increased from day 3 of pregnancy. The highest levels of EGF, TGFalpha, HB-EGF, and EGFR were detected on days 9, and 11 of pregnancy. Our data suggest that the EGF family may play a role in monkey implantation. Mol. Reprod. Dev. 55:164-174, 2000.

A Baboon (Papio anubis) simulated-pregnant model: cell specific expression of insulin-like growth factor binding protein-1 (IGFBP-1), type I IGF receptor (IGF-1 R) and retinol binding protein (RBP) in the uterus

In order to test the hypothesis that the baboon conceptus/placenta regulates the synthesis of specific proteins in the endometrium, we developed a simulated-pregnant baboon model. Baboons (n=2-6/group) were treated with increasing amounts of human chorionic gonadotrophin (hCG) for 10 or 12 days beginning on day 6 or 7 PO. Uterine tissues were obtained at day 18 PO following 12 days of hCG treatment. Animals in the day 25 and 32 PO group were treated for 10 days with hCG. Following the hCG treatment, estradiol (E) and progesterone (P) implants were inserted subcutaneously. Control groups consisted of E and P treatment only (day 25 PO), or ovariectomy on day 6 or 7 PO followed by hCG plus E and P treatment (days 18 and 25 PO). Serum samples were obtained daily or once every 2 days and analysed for E and P by radioimmunoassay. hCG activity in serum was determined by a Leydig cell bioassay. Portions of the endometrial tissue were either subjected to organ explant culture, analysed by immunocytochemistry or extracted for RNA. Peripheral serum levels of hCG, E and P in the experimental groups fell within the 95% confidence interval limits of hormone concentrations achieved during pregnancy. The morphology of the endometrium in the hCG treated baboons and pregnant baboons was similar i.e., distended convoluted glands, many spiral artery beds, a loose vacuolized stroma, and increased collagen staining. However, in the absence of hCG (E+P treatment only) the glands tended to be straight rather than corkscrew-shaped, and decreased stromal vacuolization and collagen staining was evident.(35)S-methionine labeled proteins in explant culture conditioned media (TCM) were analysed by two-dimensional SDS-PAGE and fluorography. A comparable pattern of protein synthesis was apparent in all treatment groups except for a low molecular weight (27 000-30 000 daltons) group of polypetides which only was evident in TCM from the hCG treated baboons. A similar group of proteins are also secreted by the baboon endometrium during pregnancy. The immunocytochemical localization of estrogen (ER) and progesterone receptors (PR) was comparable to that observed in pregnant baboons. IGFBP-1 localization was confined to the glandular epithelium in the hCG treated groups (intact and ovariectomized) and was virtually undetectable in the E and P treated group. The intensity of IGFBP-1 staining was variable within each of the hCG treatment groups on days 18, 25 and 32 PO. This variability was also apparent by Western blot analysis, immunoassay of proteins in TCM and on Northern blots of total RNA from the same animals. In contrast, IGF-I R immunostaining was evident in both glandular and surface epithelium of all treatment groups. Expression of RBP was confined to the basal glands. The characteristic upregulation of RBP synthesis in the functionalis observed during early pregnancy was not apparent in any of the treatment groups. In summary, these studies indicate that exogenous hCG in conjunction with E and P, can induce the general morphological and biosynthetic changes the baboon endometrium undergoes during early pregnancy. In addition, this hormonal treatment is also capable of maintaining the epithelial expression of IGFBP-1, IGF-1 and RBP. However, other factors from the conceptus appear to be necessary to induce the cell specific changes in the expression of these three proteins that are observed during pregnancy.