Role of EG-VEGF in Human Placentation: Physiological and Pathological Implications

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Tocolytic effect of a selective FP receptor antagonist in rodent models reveals an innovative approach to the treatment of preterm labor

<p>Abstract</p> <p>Background</p> <p>Management of preterm labor by tocolysis remains an unmet medical need. Prostaglandins play a major role in regulation of uterine activity and in molecular mechanisms of human labor and parturition. There is some circumstantial evidence that prostaglandin F2α by action through the prostaglandin receptor subtype FP is effective in key events during labor uterine contraction, rupture of membranes and cervical dilation. This role of FP is briefly reviewed. In this study, we tested the hypothesis that an orally active and selective FP antagonist may arrest labor and delay parturition in animal models.</p> <p>Methods</p> <p>We examined the effects of a small molecule selective antagonist of the FP receptor (AS604872) in inhibition of spontaneous uterine contraction in pregnant rat near term. We tested AS604872 for its ability to delay preterm birth in a mouse model in which the anti-progestin agent RU486 triggered parturition.</p> <p>Results</p> <p>By oral or intravenous dosing AS604872 reduced markedly and dose-dependently the spontaneous uterine contractions in late-term pregnant rats at gestational days 19–21. In pregnant mice, AS604872 delayed the preterm birth caused by RU486 administration. The effect was dose-dependent with a significant increase in the mean delivery time of 16 and 33 hours at oral doses of 30 mg/kg and 100 mg/kg, respectively, in the case of labor triggered at gestational day 14. In both models AS604872 appeared more effective than the β-agonist ritodrine.</p> <p>Conclusion</p> <p>The tocolytic activity displayed by a selective FP receptor antagonist supports a key role for the FP receptor in the pathophysiology of premature birth and demonstrates the therapeutic potential of an FP antagonist for the treatment of preterm labor cases in which uterine hyperactivity plays a dominant role.</p

Lack of Renal 11 Beta-Hydroxysteroid Dehydrogenase Type 2 at Birth, a Targeted Temporal Window for Neonatal Glucocorticoid Action in Human and Mice

International audienceBackground Glucocorticoid hormones play a major role in fetal organ maturation. Yet, excessive glucocorticoid exposure in utero can result in a variety of detrimental effects, such as growth retardation and increased susceptibility to the development of hypertension. To protect the fetus, maternal glucocorticoids are metabolized into inactive compounds by placental 11beta-hydroxysteroid dehydrogenase type2 (11βHSD2). This enzyme is also expressed in the kidney, where it prevents illicit occupation of the mineralocorticoid receptor by glucocorticoids. We investigated the role of renal 11βHSD2 in the control of neonatal glucocorticoid metabolism in the human and mouse. Methods Cortisol (F) and cortisone (E) concentrations were measured in maternal plasma, umbilical cord blood and human newborn urine using HPLC. 11βHSD2 activity was indirectly assessed by comparing the F/E ratio between maternal and neonatal plasma (placental activity) and between plasma and urine in newborns (renal activity). Direct measurement of renal 11βHSD2 activity was subsequently evaluated in mice at various developmental stages. Renal 11βHSD2 mRNA and protein expression were analyzed by quantitative RT-PCR and immunohistochemistry during the perinatal period in both species. Results We demonstrate that, at variance with placental 11βHSD2 activity, renal 11βHSD2 activity is weak in newborn human and mouse and correlates with low renal mRNA levels and absence of detectable 11βHSD2 protein. Conclusions We provide evidence for a weak or absent expression of neonatal renal 11βHSD2 that is conserved among species. This temporal and tissue-specific 11βHSD2 expression could represent a physiological window for glucocorticoid action yet may constitute an important predictive factor for adverse outcomes of glucocorticoid excess through fetal programming

Association between umbilical cord glucocorticoids and blood pressure at age 3 years

<p>Abstract</p> <p>Background</p> <p>Animal data show that decreased activity of placental 11-beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which potently inactivates glucocorticoids (e.g. cortisol) to inert forms (cortisone), allows increased access of maternal glucocorticoids to the fetus and 'programs' hypertension. Data in humans are limited. We examined in humans the association between venous umbilical cord blood glucocorticoids, a potential marker for placental 11β-HSD2 enzyme activity, and blood pressure at age 3 years.</p> <p>Methods</p> <p>Among 286 newborns in Project Viva, a prospective pre-birth cohort study based in eastern Massachusetts, we measured cortisol (<it>F</it>) and cortisone (<it>E</it>) in venous cord blood and used the ratio of <it>F/E </it>as a marker for placental 11β-HSD2 activity. We measured blood pressure (BP) when the offspring reached age 3 years. Using mixed effects regression models to control for BP measurement conditions, maternal and child characteristics, we examined the association between the <it>F/E </it>ratio and child BP.</p> <p>Results</p> <p>At age 3 years, each unit increase in the <it>F/E </it>ratio was associated with a 1.6 mm Hg increase in systolic BP (95% CI 0.0 to 3.1). The <it>F/E </it>ratio was not associated with diastolic blood pressure or birth weight for gestational age <it>z</it>-score.</p> <p>Conclusion</p> <p>A higher <it>F/E </it>ratio in umbilical venous cord blood, likely reflecting reduced placental 11β-HSD2 activity, was associated with higher systolic blood pressure at age 3 years. Our data suggest that increased fetal exposure to active maternal glucocorticoids may program later systolic blood pressure.</p

Netrin-4 Expression and Regulation by Hypoxia in Human Placenta

International audienceNetrin-4 is a well-known actor involved in axonal guidance. Recently we have reported the cellular localization of netrin-4 in human placenta. Furthermore we demonstrated its role in placental angiogenesis. Here we determined netrin-4 mRNA expression in first trimester placenta. First, we showed an increase in netrin-4 mRNA expression at 11-13 weeks of gestation (wg), suggesting a negative regulation of netrin-4 expression by hypoxia. In fact, the human placenta undergoes a transition from a low oxygenated to a highly oxygenated environment during the first trimester of pregnancy. This physiological switch in oxygen tension is a prerequisite for proper placental development and involves the hypoxia-inducible factor (HIF-1), a protein that is up-regulated under hypoxic conditions. Then, we used the trophoblast cell line BeWo to test this hypothesis. BeWo cells cultured under hypoxic conditions exhibited decreased levels of netrin-4 mRNA expression. Using siRNA strategy, hypoxia-inducible factor 1α (HIF-1α) knock-down induced a significant increase in netrin-4 mRNA expression. Altogether these results indicate that netrin-4 expression in the trophoblast cells is regulated by hypoxia via the HIF-1 pathway

Oxygen regulation of placental 11β-hydroxysteroid dehydrogenase 2: Physiological and pathological implications

International audiencePreeclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality. The genesis of PE is related to deficient trophoblast invasion of maternal spiral arteries, which might result in a reduction of placental (PL) oxygen (O(2)). An absence of increased O(2) that normally occurs around the 10-12th wk of gestation results in aberrant expression of genes that might contribute to the pathophysiology of PE. We examined the expression and regulation of PL 11 beta-hydroxysteroid dehydrogenase 2 (11 beta-HSD) in normal pregnancies and in PE. Two types of 11 beta-HSD exist in the placenta, 11 beta-HSD1 and 11 beta-HSD2. 11 beta-HSD2 is thought to protect the fetus from cortisol excess. In PE, both the expression and activity of PL 11 beta-HSD2 were reduced significantly compared with those in age-matched controls. As PE is associated with a reduction of PL O(2), we next investigated whether in normal pregnancy 11 beta-HSD2 expression changes at the time of the increase in O(2). 11 beta-HSD2 was detected as early as 5 wk, with expression limited to the syncytiotrophoblast (ST). At 10-12 wk, this expression increased and was also found in the cytotrophoblast and extravillous trophoblast. These results were substantiated by Western blot. The ability of O(2) to regulate 11 beta-HSD2 was determined both in cultures of villous explant from early gestation and in term trophoblast cells after incubation under 3% or 20% O(2). Villous explants cultured under 20% O(2) showed higher enzyme activity and expression compared with 3% O(2). Term trophoblast cells also exhibited higher enzyme activity at 20% vs. 3% O(2). No change in 11 beta-HSD1 expression was observed in early pregnancy or in PE. This is the first report to suggest that 11 beta-HSD2 is O(2) dependent in first and third trimester placenta during human gestation

Effects of cortisol and oestradiol on hepatic 11beta-hydroxysteroid dehydrogenase type 1 and glucocorticoid receptor proteins in late-gestation sheep fetus

International audienceIn the late-gestation sheep, increased fetal plasma cortisol concentration and placental oestradiol (E(2)) output contribute to fetal organ maturation, in addition to the onset of parturition. Both cortisol and E(2) are believed to regulate the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), which interconverts bioactive 11-hydroxy glucocorticoids and their inactive 11-keto metabolites. 11beta-HSD1, abundantly expressed in fetal liver, operates primarily as a reductase enzyme to produce bioactive cortisol and thus regulates local hepatic glucocorticoid concentrations. Cortisol acts through the glucocorticoid receptor (GR) present in the liver. In this study, we examined the effects of cortisol and E(2) on hepatic 11beta-HSD1 and GR in the liver of chronically catheterized sheep fetuses treated with saline (n=5), cortisol (1.35 mg/h; n=5), saline+4-hydroxyandrostendione, a P450 aromatase inhibitor (4-OHA; 1.44 mg/h; n=5), or cortisol+4-OHA (n=5). Cortisol infusion resulted in increased plasma concentrations of fetal cortisol and E(2); concurrent administration of 4-OHA attenuated the increase in plasma E(2) concentrations. Using immunohistochemistry, we showed that fetal hepatocytes expressed both 11beta-HSD1 and GR proteins. Cortisol treatment increased GR in both cytosol and nuclei of hepatocytes; concurrent administration of 4-OHA was associated with distinct nuclear GR staining. Western blot revealed that cortisol, in the absence of increased E(2) concentrations, significantly increased concentrations of 11beta-HSD1 (34 kDa) and GR (95 kDa) proteins. 11beta-HSD1 enzyme activity was measured in the liver microsomal fraction in the presence of [(3)H]cortisone (10(-)(6) M) or [(3)H]cortisol (10(-)(6) M) and NADPH (reductase activity) or NADP(+) (dehydrogenase activity) respectively. 11beta-HSD1 reductase activity was significantly greater in the presence of cortisol. In summary, we found that, in sheep during late gestation, cortisol increased both 11beta-HSD1 and GR in the fetal liver, and these effects were accentuated in the absence of increased E(2)

Expression of Prostaglandin I 2 Synthase, but Not Prostaglandin E Synthase, Changes in Myometrium of Women at Term Pregnancy

International audienceProstaglandins (PGs) act as potent uterotonins at the time of labor. Prostaglandin E synthase (PGES) is responsible for the formation of PGE(2), a uterotonin. PGI(2) is synthesized by the prostaglandin I synthase enzyme (PGIS) and contributes to relaxation in the lower uterine segment. We examined the expression of membrane-bound PGES and PGIS in myometrium from pregnant women during preterm and term labor. Tissues were collected from the lower uterine segment from preterm no labor, preterm labor, term no labor, and term labor patients and used for immunohistochemistry and Western blot analysis using specific antibodies. Immunoreactive (ir-) PGES and PGIS proteins were localized to the cytoplasm of myocytes of the myometrium and vascular smooth muscle cells. Ir-PGES was also detected in vascular endothelial cells. Western blot analyses revealed a predominant protein band of 180 kDa, and a second 16-kDa band for ir-PGES and 56-kDa band for ir-PGIS. There was no significant change in ir-PGES protein (180 or 16 kDa) or mRNA levels with preterm or term labor or gestational age. There was a significant decrease in PGIS mRNA and protein with advancing gestational age. We conclude that the gestational age decrease in the inhibitory PGIS is consistent with lessening of its influence in myometrium at the time of labor. The lack of change in PGES indicates that alterations at other points along the pathway of arachidonic acid metabolism may be of greater importance in affecting local changes in PGE(2)

Expression and Localization of Cellular Prion and COMMD1 Proteins in Human Placenta throughout Pregnancy

International audienceCopper is an essential trace element for successful pregnancy. However, the mechanisms by which copper is transported from maternal circulation to the fetus have not been clearly elucidated. Two proteins, cellular prion (PrP(C)) and COMMD1, are known to be responsible for prion diseases and canine copper toxicosis, respectively, and are thought to play a role in copper homeostasis. However, their placental expression and localization throughout human gestation are still unknown. In this study, we used quantitative RT-PCR, western blotting and immunohistochemistry to investigate in detail the expression and localization of PrP(C) and COMMD1 proteins in human placenta throughout pregnancy. Our results show that both proteins are expressed in human placenta. PrP(C) showed the highest mRNA and protein expression levels during the first trimester of pregnancy. PrP(C) and COMMD1 proteins are similarly localized within the placental villi. Both proteins are present in the syncytiotrophoblast, the cytotrophoblast, vascular endothelial cells and Hofbauer cells. These data offer some insights into possible roles for PrP(C) and COMMD1 within the placenta