Pravastatin ameliorates placental vascular defects, fetal growth, and cardiac function in a model of glucocorticoid excess

DNA methylation-mediated 11βHSD2 downregulation drives the increases in angiotensin-converting enzyme and angiotensin II within preeclamptic placentas

Preeclampsia (PE) is a complex human-specific complication frequently associated with placental pathology. The local renin-angiotensin system (RAS) in the human placenta, which plays a crucial role in regulating placental function, has been extensively documented. Glucocorticoids (GCs) are a class of steroid hormones. PE cases often have abnormalities in GCs levels and placental GCs barrier. Despite extensive speculation, there is currently no robust evidence indicating that GCs regulate placental RAS. This study aims to investigate these potential relationships. Plasma and placental samples were collected from both normal and PE pregnancies. The levels of angiotensin-converting enzyme (ACE), angiotensin II (Ang II), cortisol, and 11β-hydroxysteroid dehydrogenases (11βHSD) were analyzed. In PE placentas, cortisol, ACE, and Ang II levels were elevated, while 11βHSD2 expression was reduced. Interestingly, a positive correlation was observed between ACE and cortisol levels in the placenta. A significant inverse correlation was found between the methylation statuses within the 11βHSD2 gene promoter and its expression, meanwhile, 11βHSD2 expression was negatively correlated with cortisol and ACE levels. In vitro experiments using placental trophoblast cells confirmed that active GCs can stimulate ACE transcription and expression through the GR pathway. Furthermore, 11βHSD2 knockdown could enhance this activating effect. An in vivo study using a rat model of intrauterine GCs overexposure during mid-to-late gestation suggested that excess GCs in utero lead to increased ACE and Ang II levels in the placenta. Collectively, this study provides the first evidence of the relationships between 11βHSD2 expression, GCs barrier, ACE, and Ang II levels in the placenta. It not only contributes to understanding the pathological features of the placental GCs barrier and RAS under PE conditions, also provides important information for revealing the pathological mechanism of PE.

A Reduction in Antenatal Steroid Dose Was Associated with Reduced Cardiac Dysfunction in a Sheep Model of Pregnancy

Despite widespread use, dosing regimens for antenatal corticosteroid (ACS) therapy are poorly unoptimized. ACS therapy exerts a programming effect on fetal development, which may be associated with an increased risk of cardiovascular disease. Having demonstrated that low-dose steroid therapy is an efficacious means of maturing the preterm lung, we hypothesized that a low-dose steroid exposure would exert fewer adverse functional and transcriptional changes on the fetal heart. We tested this hypothesis using low-dose steroid therapy (10 mg delivered to the ewe over 36 h via constant infusion) and compared cardiac effects with those of a higher dose treatment (30 mg delivered to the ewe over 24 h by intramuscular injection; simulating currently employed clinical ACS regimens). Fetal cardiac function was assessed by ultrasound on the day of ACS treatment initiation. Transcriptomic analyses were performed on fetal myocardial tissue. Relative to saline control, fetuses in the higher-dose clinical treatment group had significantly lower ratios between early diastolic ventricular filling and ventricular filling during atrial systole, and showed the differential expression of myocardial hypertrophy-associated transcripts including βMHC, GADD45γ, and PPARγ. The long-term implications of these changes remain unstudied. Irrespective, optimizing ACS dosing regimens to maximize respiratory benefit while minimizing adverse effects on key organ systems, such as the heart, offers a means of improving the acute and long-term outcomes associated with this important obstetric therapy.

The Effects of Prenatal Pravastatin Treatment in the Rabbit Fetal Growth Restriction Model

Fetal growth restriction (FGR) remains without an effective prenatal treatment. Evidence from murine FGR models suggests a beneficial effect of prenatal pravastatin. Since the rabbit hemodichorial placenta more closely resembles the human condition, we investigated the effects of prenatal maternal pravastatin administration in the rabbit FGR model. At a gestational age of 25 days (term 31d), pregnant dams underwent partial uteroplacental vessel ligation (UPVL) in one uterine horn to induce FGR, leaving the other horn as a control. Dams were randomized to either receive 5 mg/kg/d pravastatin dissolved in their drinking water or normal drinking water until delivery. At GA 30d, the rabbits were delivered and were divided into four groups: control without pravastatin (C/NoPrav), FGR without pravastatin (FGR/NoPrav), FGR with pravastatin (FGR/Prav), and controls with pravastatin (C/Prav). The newborn rabbits underwent pulmonary functional assessment and neurobehavioral assessment, and they were harvested for alveolar morphometry or neuropathology. The placentas underwent histology examination and RNA expression. Birth weight was lower in the FGR groups (FGR/Prav, FGR/NoPrav), but there was no difference between FGR/Prav and C/NoPrav. No differences were noted in placental zone proportions, but eNOS in FGR/Prav placentas and VEGFR-2 in FGR/Prav and C/Prav were upregulated. There were no differences in pulmonary function assessment and alveolar morphometry. FGR/Prav kittens had increased neurosensory scores, but there were no differences in neuromotor tests, neuron density, apoptosis, and astrogliosis. In conclusion, in the rabbit FGR model, pravastatin upregulated the expression of VEGFR-2 and eNOS in FGR placentas and was associated with higher neurosensory scores, without measurable effects on birthweight, pulmonary function and morphology, and neuron density.

Combined Statin and Glucocorticoid Therapy for the Safer Treatment of Preterm Birth

BACKGROUND

Prematurity is strongly associated with poor respiratory function in the neonate. Rescue therapies include treatment with glucocorticoids due to their anti-inflammatory and maturational effects on the developing lung. However, glucocorticoid treatment in the infant can increase the risk of long-term cardiovascular complications including hypertension, cardiac, and endothelial dysfunction. Accumulating evidence implicates a molecular link between glucocorticoid excess and depletion of nitric oxide (NO) bioavailability as a mechanism underlying the detrimental effects of postnatal steroids on the heart and circulation. Therefore, combined glucocorticoid and statin therapy, by increasing NO bioavailability, may protect the developing cardiovascular system while maintaining beneficial effects on the lung.

METHODS

We investigated combined glucocorticoid and statin therapy using an established rodent model of prematurity and combined experiments of cardiovascular function in vivo, with those in isolated organs as well as measurements at the cellular and molecular levels.

RESULTS

We show that neonatal glucocorticoid treatment increases the risk of later cardiovascular dysfunction in the offspring. Underlying mechanisms include decreased circulating NO bioavailability, sympathetic hyper-reactivity, and NO-dependent endothelial dysfunction. Combined neonatal glucocorticoid and statin therapy protects the developing cardiovascular system by normalizing NO and sympathetic signaling, without affecting pulmonary maturational or anti-inflammatory effects of glucocorticoids.

CONCLUSIONS

Therefore, combined glucocorticoid and statin therapy may be safer than glucocorticoids alone for the treatment of preterm birth.

Cholic acid exposure during late pregnancy causes placental dysfunction and fetal growth restriction by reactive oxygen species-mediated activation of placental GCN2/eIF2α pathway

Epidemiological studies suggest that fetal growth restriction (FGR) caused by gestational cholestasis is associated with elevated serum cholic acid (CA). Here, we explore the mechanism by which CA induces FGR. Pregnant mice except controls were orally administered with CA daily from gestational day 13 (GD13) to GD17. Results found that CA exposure decreased fetal weight and crown-rump length, and increased the incidence of FGR in a dose-dependent manner. Furthermore, CA caused placental glucocorticoid (GC) barrier dysfunction via down-regulating the protein but not the mRNA level of placental 11β-Hydroxysteroid dehydrogenase-2 (11β-HSD2). Additionally, CA activated placental GCN2/eIF2α pathway. GCN2iB, an inhibitor of GCN2, significantly inhibited CA-induced down-regulation of 11β-HSD2 protein. We further found that CA caused excessive reactive oxygen species (ROS) production and oxidative stress in mouse placentas and human trophoblasts. NAC significantly rescued CA-induced placental barrier dysfunction by inhibiting activation of GCN2/eIF2α pathway and subsequent down-regulation of 11β-HSD2 protein in placental trophoblasts. Importantly, NAC rescued CA-induced FGR in mice. Overall, our results suggest that CA exposure during late pregnancy induces placental GC barrier dysfunction and subsequent FGR may be via ROS-mediated placental GCN2/eIF2α activation. This study provides valuable insight for understanding the mechanism of cholestasis-induced placental dysfunction and subsequent FGR.

The effect of antenatal corticosteroid use on offspring cardiovascular function: A systematic review

BACKGROUND

Antenatal corticosteroids (ACS) are recommended in threatened preterm labour to improve short-term neonatal outcome. Preclinical animal studies suggest detrimental effects of ACS exposure on offspring cardiac development; their effects in humans are unknown.

OBJECTIVES

To systematically review the human clinical literature to determine the effects of ACS on offspring cardiovascular function.

SEARCH STRATEGY

A systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines in MEDLINE, EMBASE and Cochrane databases.

SELECTION CRITERIA

Offspring who had been exposed to ACS during fetal life, in comparison with those not receiving steroids, those receiving a placebo or population data, were included. Studies not performed in humans or that did not assess cardiovascular function were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the studies, extracted the data and assessed the quality of the studies. Results were combined descriptively and analysed using a standardised Excel form.

MAIN RESULTS

Twenty-six studies including 1921 patients were included, most of which were cohort studies of mixed quality. The type of ACS exposure, gestational age at exposure, dose and number of administrations varied widely. Offspring cardiovascular outcomes were assessed from 1 day to 36 years postnatally. The most commonly assessed parameter was arterial blood pressure (18 studies), followed by echocardiography (eight studies), heart rate (five studies), electrocardiogram (ECG, three studies) and cardiac magnetic resonance imaging (MRI, one study). There were no clinically significant effects of ACS exposure on offspring blood pressure. However, there were insufficient studies assessing cardiac structure and function using echocardiography or cardiac MRI to be able to determine an effect.

CONCLUSIONS

The administration of ACS is not associated with long-term effects on blood pressure in exposed human offspring. The effects on cardiac structure and other measures of cardiac function were unclear because of the small number, heterogeneity and mixed quality of the studies. Given the preclinical and human evidence of potential harm following ACS exposure, there is a need for further research to assess central cardiac function in human offspring exposed to ACS.

Prenatal interventions for fetal growth restriction in animal models: A systematic review

Fetal growth restriction (FGR) in human pregnancy is associated with perinatal mortality, short- and long-term morbidities. No prenatal therapy is currently established despite decades of research. We aimed to review interventions in animal models for prenatal FGR treatment, and to seek the next steps for an effective clinical therapy. We registered our protocol and searched MEDLINE, Embase, and The Cochrane Library with no language restrictions, in accordance with the PRISMA guideline. We included all studies that reported the effects of any prenatal intervention in animal models of induced FGR. From 3257 screened studies, 202 describing 237 interventions were included for the final synthesis. Mice and rats were the most used animals (79%) followed by sheep (16%). Antioxidants (23%), followed by vasodilators (18%), nutrients (14%), and immunomodulators (12%) were the most tested therapy. Two-thirds of studies only reported delivery or immediate neonatal outcomes. Adverse effects were rarely reported (11%). Most studies (73%), independent of the intervention, showed a benefit in fetal survival or birthweight. The risk of bias was high, mostly due to the lack of randomization, allocation concealment, and blinding. Future research should aim to describe both short- and long-term outcomes across various organ systems in well-characterized models. Further efforts must be made to reduce selection, performance, and detection bias.

Differential expression of placental 11β-HSD2 induced by high maternal glucocorticoid exposure mediates sex differences in placental and fetal development

A variety of adverse environmental factors during pregnancy cause maternal chronic stress. Caffeine is a common stressor, and its consumption during pregnancy is widespread. Our previous study showed that prenatal caffeine exposure (PCE) increased maternal blood glucocorticoid levels and caused abnormal development of offspring. However, the placental mechanism for fetal development inhibition caused by PCE-induced high maternal glucocorticoid has not been reported. This study investigated the effects of PCE-induced high maternal glucocorticoid level on placental and fetal development by regulating placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2) expression and its underlying mechanism. First, human placenta and umbilical cord blood samples were collected from women without prenatal use of synthetic glucocorticoids. We found that placental 11β-HSD2 expression was significantly correlated with umbilical cord blood cortisol level and birth weight in male newborns but not in females. Furthermore, we established a rat model of high maternal glucocorticoids induced by PCE (caffeine, 60 mg/kg·d, ig), and found that the expression of 11β-HSD2 in male PCE placenta was decreased and negatively correlated with the maternal/fetal/placental corticosterone levels. Meanwhile, we found abnormal placental structure and nutrient transporter expression. In vitro, BeWo cells were used and confirm that 11β-HSD2 mediated inhibition of placental nutrient transporter expression induced by high levels of glucocorticoid. Finally, combined with the animal and cell experiments, we further confirmed that high maternal glucocorticoid could activate the GR-C/EBPα-Egr1 signaling pathway, leading to decreased expression of 11β-HSD2 in males. However, there was no significant inhibition of placental 11β-HSD2 expression, placental and fetal development in females. In summary, we confirmed that high maternal glucocorticoids could regulate placental 11β-HSD2 expression in a sex-specific manner, leading to differences in placental and fetal development. This study provides the theoretical and experimental basis for analyzing the inhibition of fetoplacental development and its sex difference caused by maternal stress.

Analysis of Placental Arteriovenous Formation Reveals New Insights Into Embryos With Congenital Heart Defects

The placental vasculature provides the developing embryo with a circulation to deliver nutrients and dispose of waste products. However, in the mouse, the vascular components of the chorio-allantoic placenta have been largely unexplored due to a lack of well-validated molecular markers. This is required to study how these blood vessels form in development and how they are impacted by embryonic or maternal defects. Here, we employed marker analysis to characterize the arterial/arteriole and venous/venule endothelial cells (ECs) during normal mouse placental development. We reveal that placental ECs are potentially unique compared with their embryonic counterparts. We assessed embryonic markers of arterial ECs, venous ECs, and their capillary counterparts-arteriole and venule ECs. Major findings were that the arterial tree exclusively expressed Dll4, and venous vascular tree could be distinguished from the arterial tree by Endomucin (EMCN) expression levels. The relationship between the placenta and developing heart is particularly interesting. These two organs form at the same stages of embryogenesis and are well known to affect each other's growth trajectories. However, although there are many mouse models of heart defects, these are not routinely assessed for placental defects. Using these new placental vascular markers, we reveal that mouse embryos from one model of heart defects, caused by maternal iron deficiency, also have defects in the formation of the placental arterial, but not the venous, vascular tree. Defects to the embryonic cardiovascular system can therefore have a significant impact on blood flow delivery and expansion of the placental arterial tree.

Life Course Impact of Glucocorticoids During Pregnancy on Muscle Development and Function

Maternal stress, such as maternal obesity, can induce severe gestational disease and hormonal disorder which may disrupt fetal organ maturation and further cause endangered early or future health in offspring. During fetal development, glucocorticoids are essential for the maturation of organ systems. For instance, in clinical applications, glucocorticoids are commonly utilized to pregnant women with the risk of preterm delivery to reduce mortality of the newborns. However, exposure of excessive glucocorticoids at embryonic and fetal developmental stages can cause diseases such as cardiovascular disease and muscle atrophy in adulthood. Effects of excessive glucocorticoids on human health are well-recognized and extensively studied. Nonetheless, effects of these hormones on farm animal growth and development, particularly on prenatal muscle development, and postnatal growth, did not attract much attention until the last decade. Here, we provided a short review of the recent progress relating to the effect of glucocorticoids on prenatal skeletal muscle development and postnatal muscle growth as well as heart muscle development and cardiovascular disease during life course.

Evaluating the Effect of Pravastatin in Early-Onset Fetal Growth Restriction: A Nonrandomized and Historically Controlled Pilot Study

OBJECTIVE

This study aimed to analyze the effect of pravastatin on angiogenic factors, feto-maternal Doppler findings and pregnancy outcomes in women with early-onset fetal growth restriction (FGR) treated with pravastatin compared with nontreated controls.

STUDY DESIGN

This was a pilot study conducted between March 2016 and September 2017. Women with single pregnancies and FGR diagnosed at ≤ 28 weeks of gestation were offered 40 mg of pravastatin daily. Doppler progression, soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) values, and pregnancy outcomes were assessed and compared with consecutive historical controls. Controls were matched to treated women for gestational age, maternal characteristics, maternal and obstetric history, Doppler severity classification, and angiogenic factors at diagnosis. The sFlt-1/PlGF was measured in maternal serum at two different times: before pravastatin was started (ratio M0) and during pravastatin treatment (ratio M1). Doppler severity was classified into four categories: normal, mild, moderate, and severe.

RESULTS

A total of 38 women were enrolled in this study. No differences were observed in baseline characteristics between groups. However, when compared with the ratio M0, M1 was increased by a median (interquartile range) of 67.0 (-34.8 to 197.3) in the control group but decreased by a median (interquartile range) of -10.1 (-53.1 to -0.07) in the pravastatin treated group (p < 0.001). No significant differences were observed in Doppler progression throughout pregnancy. Median interval from diagnosis to delivery was extended by 16.5 days, the median newborn birthweight was increased from 1,040 to 1,300 g, and the number of women with preeclampsia decreased from 9 (47.4%) to 6 (31.6%) in treated women; however, these trends were not statistically significant.

CONCLUSION

In women with early-onset FGR, treatment with pravastatin 40 mg daily was associated with significant improvement in the angiogenic profile. Additionally, median pregnancy duration and median birthweight increased and the incidence of PE was reduced in treated women. Nevertheless, since this pilot study was underpowered, none of these differences were statistically significant.

KEY POINTS

· Pravastatin improves sFlt-1/PlGF in FGR.. · Pregnancy duration tended to be greater in treated women.. · Birthweight tended to be greater in treated women..

Investigating the Upstream and Downstream Hemodynamic Boundary Conditions of Healthy and Growth-Restricted Rat Feto-Placental Arterial Networks

The placenta uniquely develops to orchestrate maternal adaptations and support fetal growth and development. The expansion of the feto-placental vascular network, in part, underpins function. However it is unclear how vascular development is synergistically influenced by hemodynamics and how impairment may lead to fetal growth restriction (FGR). Here, we present a robust framework consisting of ex vivo placental casting, imaging and computational fluid dynamics of rat feto-placental networks where we investigate inlet (steady and transient) and outlet (zero-pressure, Murray's Law, asymmetric fractal trees and porous blocks) boundary conditions in a model of growth-restriction. We show that the Murray's Law flow-split boundary condition is not always appropriate and that mean steady-state inlet conditions produce comparable results to transient flow. However, we conclude that transient simulations should be adopted as they provide a larger amount of valuable data, a necessity to bridge the current knowledge gap in placental biomechanics. We also show preliminary data on changes in flow, shear stress, and flow deceleration between control and growth-restricted feto-placental networks. Our proposed framework provides a standardized approach for structural and hemodynamic analysis of feto-placental vasculature and has the potential to enhance our understanding of placental function.

Dexamethasone-induced intrauterine growth restriction modulates expression of placental vascular growth factors and fetal and placental growth

Prenatal exposure to glucocorticoids (GC) is a central topic of interest in medicine since GCs are essential for the maturation of fetal organs and intrauterine growth. Synthetic glucocorticoids, which are used in obstetric practice, exert beneficial effects on the fetus, but have also been reported to lead to intrauterine growth retardation (IUGR). In this study, a model of growth restriction in mice was established through maternal administration of dexamethasone during late gestation. We hypothesised that GC overexposure may adversely affect placental angiogenesis and fetal and placental growth. Female BALB/c mice were randomly assigned to control or dexamethasone treatment, either left to give birth or euthanised on days 15, 16, 17 and 18 of gestation followed by collection of maternal and fetal tissue. The IUGR rate increased to 100% in the dexamethasone group (8 mg/kg body weight on gestational days 14 and 15) and pups had clinical features of symmetrical IUGR at birth. Dexamethasone administration significantly decreased maternal body weight gain and serum corticosterone levels. Moreover, prenatal dexamethasone treatment not only induced fetal growth retardation but also decreased placental weight. In IUGR placentas, VEGFA protein levels and mRNA expression of VEGF receptors were reduced and NOS activity was lower. Maternal dexamethasone administration also reduced placental expression of the GC receptor, αGR. We demonstrated that maternal dexamethasone administration causes fetal and placental growth restriction. Furthermore, we propose that the growth retardation induced by prenatal GC overexposure may be caused, at least partially, by an altered placental angiogenic profile.

Contribution of placental 11β-HSD2 to the pathogenesis of preeclampsia

Preeclampsia, a major human pregnancy-specific disorder, leads to maternal and fetal morbidity and mortality. Here we reported that 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), an enzyme that degrades active glucocorticoids, is one of the key factors that contributes to preeclampsia development. In the pregnant rat model, we firstly confirmed that administration of 11β-HSD2 inhibitor carbenoxolone (CBX) subcutaneously or by placenta-targeted delivery system could lead to a decrease in placental 11β-HSD2 expression and activity and an increase in corticosterone level in placenta and maternal circulation. Then, we showed that subcutaneous administration and placenta-targeted delivery of CBX resulted in the hallmark of preeclampsia-like features including hypertension, proteinuria, renal damages as well as elevated circulatory soluble fms-like tyrosine kinase 1 (sFlt1) and increased sFlt1/placental growth factor (PlGF) ratio in pregnant rats. These animals displayed decreased trophoblast invasion in uterus, impaired spiral artery remodeling, and reduced placental blood flow. Preeclampsia-like features could also be induced by administration of dexamethasone in pregnant rats. In the cultured human trophoblast models, we found that cortisol only inhibited migration and invasion of the extravillous trophoblasts with 11β-HSD2 knockdown, and promoted sFlt1 release in the cultured syncytiotrophoblasts with 11β-HSD2 knockdown. Furthermore, we elucidated that cortisol stimulated a disintegrin and metalloprotease (ADAM)17 expression in placentas, thereby promoting sFlt1 release in placenta. Collectively, our study provided the evidence that placental 11β-HSD2 dysfunction plays a key role in the development of preeclampsia and immediately identified innovative target to counteract preeclampsia.

Advances in imaging feto-placental vasculature: new tools to elucidate the early life origins of health and disease

Optimal placental function is critical for fetal development, and therefore a crucial consideration for understanding the developmental origins of health and disease (DOHaD). The structure of the fetal side of the placental vasculature is an important determinant of fetal growth and cardiovascular development. There are several imaging modalities for assessing feto-placental structure including stereology, electron microscopy, confocal microscopy, micro-computed tomography, light-sheet microscopy, ultrasonography and magnetic resonance imaging. In this review, we present current methodologies for imaging feto-placental vasculature morphology ex vivo and in vivo in human and experimental models, their advantages and limitations and how these provide insight into placental function and fetal outcomes. These imaging approaches add important perspective to our understanding of placental biology and have potential to be new tools to elucidate a deeper understanding of DOHaD.

Sex-specific regulation of stress-induced fetal glucocorticoid surge by the mouse placenta

Antenatal stress increases the prevalence of diseases in later life, which shows a strong sex-specific effect. However, the underlying mechanisms remain unknown. Maternal glucocorticoids can be elevated by stress and are potential candidates to mediate the effects of stress on the offspring sex-specifically. A comprehensive evaluation of dynamic maternal and placental mechanisms modulating fetal glucocorticoid exposure upon maternal stress was long overdue. Here, we addressed this gap in knowledge by investigating sex-specific responses to midgestational stress in mice. We observed increased levels of maternal corticosterone, the main glucocorticoid in rodents, along with higher corticosteroid-binding globulin levels at midgestation in C57Bl/6 dams exposed to sound stress. This resulted in elevated corticosterone in female fetuses, whereas male offspring were unaffected. We identified that increased placental expression of the glucocorticoid-inactivating enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2; Hsd11b2 gene) and ATP-binding cassette transporters, which mediate glucocorticoid efflux toward maternal circulation, protect male offspring from maternal glucocorticoid surges. We generated mice with an Hsd11b2 placental-specific disruption (Hsd11b2^PKO) and observed moderately elevated corticosterone levels in offspring, along with increased body weight. Subsequently, we assessed downstream glucocorticoid receptors and observed a sex-specific differential modulation of placental Tsc22d3 expression, which encodes the glucocorticoid-induced leucine zipper protein in response to stress. Taken together, our observations highlight the existence of unique and well-orchestrated mechanisms that control glucocorticoid transfer, exposure, and metabolism in the mouse placenta, pinpointing toward the existence of sex-specific fetal glucocorticoid exposure windows during gestation in mice.

Antenatal dexamethasone treatment transiently alters diastolic function in the mouse fetal heart

Endogenous glucocorticoid action is important in the structural and functional maturation of the fetal heart. In fetal mice, although glucocorticoid concentrations are extremely low before E14.5, glucocorticoid receptor (GR) is expressed in the heart from E10.5. To investigate whether activation of cardiac GR prior to E14.5 induces precocious fetal heart maturation, we administered dexamethasone in the drinking water of pregnant dams from E12.5 to E15.5. To test the direct effects of glucocorticoids upon the cardiovascular system we used SMGRKO mice, with Sm22-Cre-mediated disruption of GR in cardiomyocytes and vascular smooth muscle. Contrary to expectations, echocardiography showed no advancement of functional maturation of the fetal heart. Moreover, litter size was decreased 2 days following cessation of antenatal glucocorticoid exposure, irrespective of fetal genotype. The myocardial performance index and E/A wave ratio, markers of fetal heart maturation, were not significantly affected by dexamethasone treatment in either genotype. Dexamethasone treatment transiently decreased the myocardial deceleration index (MDI; a marker of diastolic function), in control fetuses at E15.5, with recovery by E17.5, 2 days after cessation of treatment. MDI was lower in SMGRKO than in control fetuses and was unaffected by dexamethasone. The transient decrease in MDI was associated with repression of cardiac GR in control fetuses following dexamethasone treatment. Measurement of glucocorticoid levels in fetal tissue and hypothalamic corticotropin-releasing hormone (Crh) mRNA levels suggest complex and differential effects of dexamethasone treatment upon the hypothalamic-pituitary-adrenal axis between genotypes. These data suggest potentially detrimental and direct effects of antenatal glucocorticoid treatment upon fetal heart function.

Combined Antioxidant and Glucocorticoid Therapy for Safer Treatment of Preterm Birth

Ante- and postnatal glucocorticoid therapy reduces morbidity and mortality in the preterm infant, and it is therefore one of the best examples of the successful translation of basic experimental science into human clinical practice. However, accruing evidence derived from human clinical studies and from experimental studies in animal models raise serious concerns about potential long-term adverse effects of treatment on growth and neurological and cardiovascular function in the offspring. This review explores whether combined antioxidant and glucocorticoid therapy may be safer than glucocorticoid therapy alone for the treatment of preterm birth.

The Placental Transcriptome in Late Gestational Hypoxia Resulting in Murine Intrauterine Growth Restriction Parallels Increased Risk of Adult Cardiometabolic Disease

Intrauterine growth restriction (IUGR) enhances risk for adult onset cardiovascular disease (CVD). The mechanisms underlying IUGR are poorly understood, though inadequate blood flow and oxygen/nutrient provision are considered common endpoints. Based on evidence in humans linking IUGR to adult CVD, we hypothesized that in murine pregnancy, maternal late gestational hypoxia (LG-H) exposure resulting in IUGR would result in (1) placental transcriptome changes linked to risk for later CVD, and 2) adult phenotypes of CVD in the IUGR offspring. After subjecting pregnant mice to hypoxia (10.5% oxygen) from gestational day (GD) 14.5 to 18.5, we undertook RNA sequencing from GD19 placentas. Functional analysis suggested multiple changes in structural and functional genes important for placental health and function, with maximal dysregulation involving vascular and nutrient transport pathways. Concordantly, a ~10% decrease in birthweights and ~30% decrease in litter size was observed, supportive of placental insufficiency. We also found that the LG-H IUGR offspring exhibit increased risk for CVD at 4 months of age, manifesting as hypertension, increased abdominal fat, elevated leptin and total cholesterol concentrations. In summary, this animal model of IUGR links the placental transcriptional response to the stressor of gestational hypoxia to increased risk of developing cardiometabolic disease.

The Role of 11β-Hydroxy Steroid Dehydrogenase Type 2 in Glucocorticoid Programming of Affective and Cognitive Behaviours

Developmental exposure to stress hormones, i.e. glucocorticoids, is central to the process of prenatal programming of later-life health. Glucocorticoid overexposure, through stress or exogenous glucocorticoids, results in a reduced birthweight, as well as affective and neuropsychiatric outcomes in adults, combined with altered hypothalamus-pituitary-adrenal (HPA) axis activity. As such, glucocorticoids are tightly regulated during development through the presence of the metabolizing enzyme 11β-hydroxysteroid dehydrogenase type 2 (HSD2). HSD2 is highly expressed in 2 hubs during development, i.e. the placenta and the fetus itself, protecting the fetus from inappropriate glucocorticoid exposure early in gestation. Through manipulation of HSD2 expression in the mouse placenta and fetal tissues, we are able to determine the relative contribution of glucocorticoid exposure in each compartment. Feto-placental HSD2 deletion resulted in a reduced birthweight and the development of anxiety- and depression-like behaviours in adult mice. The placenta itself is altered by glucocorticoid overexposure, which causes reduced placental weight and vascular arborisation. Furthermore, altered flow and resistance in the umbilical vessels and modification of fetal heart function and development are observed. However, brain-specific HSD2 removal (HSD2BKO) also generated adult phenotypes of depressive-like behaviour and memory deficits, demonstrating the importance of fetal brain HSD2 expression in development. In this review we will discuss potential mechanisms underpinning early-life programming of adult neuropsychiatric disorders and the novel therapeutic potential of statins.

Glucocorticoids, antenatal corticosteroid therapy and fetal heart maturation

Glucocorticoids are essential in mammals to mature fetal organs and tissues in order to survive after birth. Hence, antenatal glucocorticoid treatment (termed antenatal corticosteroid therapy) can be life-saving in preterm babies and is commonly used in women at risk of preterm birth. While the effects of glucocorticoids on lung maturation have been well described, the effects on the fetal heart remain less clear. Experiments in mice have shown that endogenous glucocorticoid action is required to mature the fetal heart. However, whether the potent synthetic glucocorticoids used in antenatal corticosteroid therapy have similar maturational effects on the fetal heart is less clear. Moreover, antenatal corticosteroid therapy may increase the risk of cardiovascular disease in adulthood. Here, we present a narrative review of the evidence relating to the effects of antenatal glucocorticoid action on the fetal heart and discuss the implications for antenatal corticosteroid therapy.

Recent Advances in Placenta-Heart Interactions

Congenital heart defects (CHD) occur in ∼1 in every 100 live births. In addition, an estimated 10% of fetal loss is due to severe forms of CHD. This makes heart defects the most frequently occurring birth defect and single cause of in utero fatality in humans. There is considerable evidence that CHD is heritable, indicating a strong contribution from genetic risk factors. There are also known external environmental exposures that are significantly associated with risk for CHD. Hence, the majority of CHD cases have long been considered to be multifactorial, or generally caused by the confluence of several risk factors potentially from genetic, epigenetic, and environmental sources. Consequently, a specific cause can be very difficult to ascertain, although patterns of associations are very important to prevention. While highly protective of the fetus, the in utero environment is not immune to insult. As the conduit between the mother and fetus, the placenta plays an essential role in maintaining fetal health. Since it is not a fully-formed organ at the onset of pregnancy, the development of the placenta must keep pace with the growth of the fetus in order to fulfill its critical role during pregnancy. In fact, the placenta and the fetal heart actually develop in parallel, a phenomenon known as the placenta–heart axis. This leaves the developing heart particularly vulnerable to early placental insufficiency. Both organs share several developmental pathways, so they also share a common vulnerability to genetic defects. In this article we explore the coordinated development of the placenta and fetal heart and the implications for placental involvement in the etiology and pathogenesis of CHD.

cAMP/PKA/EGR1 signaling mediates the molecular mechanism of ethanol-induced inhibition of placental 11β-HSD2 expression

It is known that inhibiting 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) expression in the placenta can cause fetal over-exposure to maternal glucocorticoids and induce intrauterine growth restriction (IUGR); these effects ultimately increase the risk of adult chronic diseases. This study aimed to investigate the molecular mechanism of the prenatal ethanol exposure (PEE)-induced inhibition of placental 11β-HSD2 expression. Pregnant Wistar rats were intragastrically administered ethanol (4 g/kg/d) from gestational days 9 to 20. The levels of maternal and fetal serum corticosterone and placental 11β-HSD2-related gene expression were analyzed. Furthermore, we investigated the mechanism of reduced placental 11β-HSD2 expression induced by ethanol treatment (15-60 mM) in HTR-8/SVneo cells. In vivo, PEE decreased fetal body weights and increased maternal and fetal serum corticosterone and early growth response factor 1 (EGR1) expression levels. Moreover, histone modification changes (decreased acetylation and increased di-methylation of H3K9) to the HSD11B2 promoter and lower 11β-HSD2 expression levels were observed. In vitro, ethanol decreased cAMP/PKA signaling and 11β-HSD2 expression and increased EGR1 expression in a concentration-dependent manner. A cAMP agonist and EGR1 siRNA reversed the ethanol-induced inhibition of 11β-HSD2 expression. Together, PEE reduced placental 11β-HSD2 expression, and the underlying mechanism is associated with ethanol-induced histone modification changes to the HSD11B2 promoter through the cAMP/PKA/EGR1 pathway.

Recent and emerging reproductive biology research in Australia and New Zealand: highlights from the Society for Reproductive Biology Annual Meeting, 2017

Research in reproductive science is essential to promote new developments in reproductive health and medicine, agriculture and conservation. The Society for Reproductive Biology (SRB) 2017 conference held in Perth (WA, Australia) provided a valuable update on current research programs in Australia and New Zealand. This conference review delivers a dedicated summary of significant questions, emerging concepts and innovative technologies presented in the symposia. This research demonstrates significant advances in the identification of precursors for a healthy pregnancy, birth and child, and discusses how these factors can influence disease risk. A key theme included preconception parental health and its effect on gametogenesis, embryo and fetal development and placental function. In addition, the perturbation of key developmental checkpoints was shown to contribute to a variety of pathological states that have the capacity to affect health and fertility. Importantly, the symposia discussed in this review emphasised the role of reproductive biology as a conduit for understanding the transmission of non-communicable diseases, such as metabolic disorders and cancers. The research presented at SRB 2017 has revealed key findings that have the prospect to change not only the fertility of the present generation, but also the health and reproductive capacity of future generations.

Treating the dysfunctional placenta

Placental dysfunction underlies major obstetric diseases such as pre-eclampsia and fetal growth restriction (FGR). Whilst there has been a little progress in prophylaxis, there are still no treatments for placental dysfunction in normal obstetric practice. However, a combination of increasingly well-described in vitro systems for studying the human placenta, together with the availability of more appropriate animal models of pre-eclampsia and FGR, has facilitated a recent surge in work aimed at repurposing drugs and therapies, developed for other conditions, as treatments for placental dysfunction. This review: (1) highlights potential candidate drug targets in the placenta - effectors of improved uteroplacental blood flow, anti-oxidants, heme oxygenase induction, inhibition of HIF, induction of cholesterol synthesis pathways, increasing insulin-like growth factor II availability; (2) proposes an experimental pathway for taking a potential drug or treatment for placental dysfunction from concept through to early phase clinical trials, utilizing techniques for studying the human placenta in vitro and small animal models, particularly the mouse, for in vivo studies; (3) describes the data underpinning sildenafil citrate and adenovirus expressing vascular endothelial growth as potential treatments for placental dysfunction and summarizes recent research on other potential treatments. The importance of sharing information from such studies even when no effect is found, or there is an adverse outcome, is highlighted. Finally, the use of adenoviral vectors or nanoparticle carriers coated with homing peptides to selectively target drugs to the placenta is highlighted: such delivery systems could improve efficacy and reduce the side effects of treating the dysfunctional placenta.