Role of the placenta in fetal programming: underlying mechanisms and potential interventional approaches

Placental weight mediates the effects of prenatal factors on fetal growth: the extent differs by preterm status

OBJECTIVE

Elevated pre-pregnancy BMI, excessive gestational weight gain (GWG), and gestational diabetes mellitus (GDM) are known determinants of fetal growth. The role of placental weight is unclear. We aimed to examine the extent to which placental weight mediates the associations of pre-pregnancy BMI, GWG, and GDM with birth weight-for-gestational age, and whether the relationships differ by preterm status.

DESIGN AND METHODS

We examined 1,035 mother-infant pairs at birth from the Boston Birth Cohort. Data were collected by questionnaire and clinical measures. Placentas were weighed without membranes or umbilical cords. We performed sequential models excluding and including placental weight, stratified by preterm status.

RESULTS

We found that 21% of mothers were obese, 42% had excessive GWG, and 5% had GDM. Forty-one percent were preterm. Among term births, after adjustment for sex, gestational age, maternal age, race, parity, education, smoking, and stress during pregnancy, birth weight-for-gestational age z-score was 0.55 (0.30, 0.80) units higher for pre-pregnancy obesity vs. normal weight. It was 0.34 (0.13, 0.55) higher for excessive vs. adequate GWG, 0.67 (0.24, 1.10) for GDM vs. no DM, with additional adjustment for pre-pregnancy BMI. Adding placental weight to the models attenuated the estimates for pre-pregnancy obesity by 20%, excessive GWG by 32%, and GDM by 21%. Among preterm infants, GDM was associated with 0.67 (0.34, 1.00) higher birth weight-for-gestational age z-score, but pre-pregnancy obesity and excessive GWG were not. Attenuation by placental weight was 36% for GDM.

CONCLUSIONS

These results suggest that placental weight partially mediates the effects of pre-pregnancy obesity, GDM, and excessive GWG on fetal growth among term infants.

Newborn body fat: associations with maternal metabolic state and placental size

BACKGROUND

Neonatal body composition has implications for the health of the newborn both in short and long term perspective. The objective of the current study was first to explore the association between maternal BMI and metabolic parameters associated with BMI and neonatal percentage body fat and to determine to which extent any associations were modified if adjusting for placental weight. Secondly, we examined the relations between maternal metabolic parameters associated with BMI and placental weight.

METHODS

The present work was performed in a subcohort (n = 207) of the STORK study, an observational, prospective study on the determinants of fetal growth and birthweight in healthy pregnancies at Oslo University Hospital, Norway. Fasting glucose, insulin, triglycerides, free fatty acids, HDL- and total cholesterol were measured at week 30-32. Newborn body composition was determined by Dual-Energy X-Ray Absorptiometry (DXA). Placenta was weighed at birth. Linear regression models were used with newborn fat percentage and placental weight as main outcomes.

RESULTS

Maternal BMI, fasting glucose and gestational age were independently associated with neonatal fat percentage. However, if placental weight was introduced as a covariate, only placental weight and gestational age remained significant. In the univariate model, the determinants of placenta weight included BMI, insulin, triglycerides, total- and HDL-cholesterol (negatively), gestational weight gain and parity. In the multivariable model, BMI, total cholesterol HDL-cholesterol, gestational weight gain and parity remained independent covariates.

CONCLUSION

Maternal BMI and fasting glucose were independently associated with newborn percentage fat. This effect disappeared by introducing placental weight as a covariate. Several metabolic factors associated with maternal BMI were associated with placental weight, but not with neonatal body fat. Our findings are consistent with a concept that the effects of maternal BMI and a number of BMI-related metabolic factors on fetal fat accretion to a significant extent act by modifying placental weight.

Plasmodium falciparum malaria elicits inflammatory responses that dysregulate placental amino acid transport

Placental malaria (PM) can lead to poor neonatal outcomes, including low birthweight due to fetal growth restriction (FGR), especially when associated with local inflammation (intervillositis or IV). The pathogenesis of PM-associated FGR is largely unknown, but in idiopathic FGR, impaired transplacental amino acid transport, especially through the system A group of amino acid transporters, has been implicated. We hypothesized that PM-associated FGR could result from impairment of transplacental amino acid transport triggered by IV. In a cohort of Malawian women and their infants, the expression and activity of system A (measured by Na⁺-dependent ¹⁴C-MeAIB uptake) were reduced in PM, especially when associated with IV, compared to uninfected placentas. In an in vitro model of PM with IV, placental cells exposed to monocyte/infected erythrocytes conditioned medium showed decreased system A activity. Amino acid concentrations analyzed by reversed phase ultra performance liquid chromatography in paired maternal and cord plasmas revealed specific alterations of amino acid transport by PM, especially with IV. Overall, our data suggest that the fetoplacental unit responds to PM by altering its placental amino acid transport to maintain adequate fetal growth. However, IV more profoundly compromises placental amino acid transport function, leading to FGR. Our study offers the first pathogenetic explanation for FGR in PM.

Malaria infection during pregnancy can cause fetal growth restriction and low birthweight associated with high infant mortality and morbidity rates. The pathogenesis of fetal growth restriction in placental malaria is largely unknown, but in other pathological pregnancies, impaired transplacental amino acid transport has been implicated. In a cohort of Malawian women and their infants, we found that placental malaria, especially when associated with local inflammation, was associated with decreased expression and activity of an important group of amino acid placental transporters. Using an in vitro model of placental malaria with local inflammation, we discovered that maternal monocyte products could impair the activity of amino acid transporters on placental cells. Amino acid concentrations in paired maternal and cord plasmas revealed specific alterations of amino acid transport by placental malaria, especially with local inflammation. Overall, our data suggest that, more than malaria infection per se, the local inflammation it triggers compromises placental amino acid transport function, leading to fetal growth restriction. Greater understanding of the mechanisms involved, combined with interventions to improve fetal growth in malaria, are important priorities in areas of the world where the co-existence of malaria and maternal malnutrition threatens the health and lives of millions of young babies.

Ex vivo perfusion of mid-to-late-gestation mouse placenta for maternal-fetal interaction studies during pregnancy

Ex vivo perfusion systems offer a reliable, reproducible method for studying acute physiological responses of an organ to various environmental manipulations. Unlike in vitro culture systems, the cellular organization, compartmentalization and three-dimensional structure of ex vivo-perfused organs are maintained. These particular parameters are crucial for the normal physiological function of the placenta, which supports fetal growth through transplacental exchange, nutritional synthesis and metabolism, growth factor promotion and regulation of both maternally and fetally derived molecules. The perfusion system described here, which can be completed in 4-5 h, allows for integrated, physiological studies of de novo synthesis and metabolism and transport of materials across the live mouse placenta, not only throughout a normal gestation period but also following a variety of individual or combined genetic and environmental perturbations compromising placental function.

Paternal diet-induced obesity retards early mouse embryo development, mitochondrial activity and pregnancy health

Worldwide, 48% of adult males are overweight or obese. An association between infertility and excessive body weight is now accepted, although focus remains primarily on females. It has been shown that parental obesity results in compromised embryo development, disproportionate changes in embryo metabolism and reduced blastocyst cell number. The aim of this study was to determine whether paternal obesity has negative effects on the resultant embryo. Specifically, using in vitro fertilisation (IVF), we wanted to isolate the functional effects of obesity on sperm by examining the subsequent embryo both pre- and post-implantation. Epididymal sperm was collected from age matched normal and obese C57BL/6 mice and cryopreserved for subsequent IVF with oocytes collected from Swiss females (normal diet/weight). Obesity was induced in male mice by feeding a high fat diet of 22% fat for 10 weeks. Resultant embryos were cultured individually and development monitored using time-lapse microscopy. Paternal obesity resulted in a significant delay in preimplantation embryo development as early as syngamy (P<0.05). Metabolic parameters were measured across key developmental stages, demonstrating significant reduction in mitochondrial membrane potential (P<0.01). Blastocysts were stained to determine trophectoderm (TE) and inner cell mass (ICM) cell numbers, revealing significant differences in the ratio of cell allocation to TE and ICM lineages (P<0.01). Functional studies examining blastocyst attachment, growth and implantation demonstrated that blastocysts derived from sperm of obese males displayed significantly reduced outgrowth on fibronectin in vitro (P<0.05) and retarded fetal development in vivo following embryo transfer (P<0.05). Taken together, these data clearly demonstrate that paternal obesity has significant negative effects on the embryo at a variety of key early developmental stages, resulting in delayed development, reduced placental size and smaller offspring.

Regulation of nutrient transport across the placenta

Abnormal fetal growth, both growth restriction and overgrowth, is associated with perinatal complications and an increased risk of metabolic and cardiovascular disease later in life. Fetal growth is dependent on nutrient availability, which in turn is related to the capacity of the placenta to transport these nutrients. The activity of a range of nutrient transporters has been reported to be decreased in placentas of growth restricted fetuses, whereas at least some studies indicate that placental nutrient transport is upregulated in fetal overgrowth. These findings suggest that changes in placental nutrient transport may directly contribute to the development of abnormal fetal growth. Detailed information on the mechanisms by which placental nutrient transporters are regulated will therefore help us to better understand how important pregnancy complications develop and may provide a foundation for designing novel intervention strategies. In this paper we will focus on recent studies of regulatory mechanisms that modulate placental transport of amino acids, fatty acids, and glucose.

Mammalian target of rapamycin signalling modulates amino acid uptake by regulating transporter cell surface abundance in primary human trophoblast cells

Abnormal fetal growth increases the risk for perinatal complications and predisposes for the development of obesity, diabetes and cardiovascular disease later in life. Emerging evidence suggests that changes in placental amino acid transport directly contribute to altered fetal growth. However, the molecular mechanisms regulating placental amino acid transport are largely unknown. Here we combined small interfering (si) RNA-mediated silencing approaches with protein expression/localization and functional studies in cultured primary human trophoblast cells to test the hypothesis that mammalian target of rapamycin complex 1 (mTORC1) and 2 (mTORC2) regulate amino acid transporters by post-translational mechanisms. Silencing raptor (inhibits mTORC1) or rictor (inhibits mTORC2) markedly decreased basal System A and System L amino acid transport activity but had no effect on growth factor-stimulated amino acid uptake. Simultaneous inhibition of mTORC1 and 2 completely inhibited both basal and growth factor-stimulated amino acid transport activity. In contrast, mTOR inhibition had no effect on serotonin transport. mTORC1 or mTORC2 silencing markedly decreased the plasma membrane expression of specific System A (SNAT2, SLC38A2) and System L (LAT1, SLC7A5) transporter isoforms without affecting global protein expression. In conclusion, mTORC1 and mTORC2 regulate human trophoblast amino acid transporters by modulating the cell surface abundance of specific transporter isoforms. This is the first report showing regulation of amino acid transport by mTORC2. Because placental mTOR activity and amino acid transport are decreased in human intrauterine growth restriction our data are consistent with the possibility that dysregulation of placental mTOR plays an important role in the development of abnormal fetal growth.

Effects of gestational age and surface modification on materno-fetal transfer of nanoparticles in murine pregnancy

Nanoparticle exposure in pregnancy may result in placental damage and fetotoxicity; however, the factors that determine fetal nanoparticle exposure are unclear. Here we have assessed the effect of gestational age and nanoparticle composition on fetal accumulation of maternally-administered nanomaterials in mice. We determined the placental and fetal uptake of 13 nm gold nanoparticles with different surface modifications (ferritin, PEG and citrate) following intravenous administration at E5.5-15.5. We showed that prior to E11.5, all tested nanoparticles could be visualized and detected in fetal tissues in significant amounts; however, fetal gold levels declined dramatically post-E11.5. In contrast, Au-nanoparticle accumulation in the extraembryonic tissues (EET) increased 6–15 fold with gestational age. Fetal and EET accumulation of ferritin- and PEG-modified nanoparticles was considerably greater than citrate-capped nanoparticles. No signs of toxicity were observed. Fetal exposure to nanoparticles in murine pregnancy is, therefore, influenced by both stage of embryonic/placental maturation and nanoparticle surface composition.

Roles of nitric oxide and asymmetric dimethylarginine in pregnancy and fetal programming

Nitric oxide (NO) regulates placental blood flow and actively participates in trophoblast invasion and placental development. Asymmetric dimethylarginine (ADMA) can inhibit NO synthase, which generates NO. ADMA has been associated with uterine artery flow disturbances such as preeclampsia. Substantial experimental evidence has reliably supported the hypothesis that an adverse in utero environment plays a role in postnatal physiological and pathophysiological programming. Growing evidence suggests that the placental nitrergic system is involved in epigenetic fetal programming. In this review, we discuss the roles of NO and ADMA in normal and compromised pregnancies as well as the link between placental insufficiency and epigenetic fetal programming.

Optimize dietary intake of vitamin D: an epigenetic perspective

PURPOSE OF REVIEW

Vitamin D has received global attention because of its many health benefits. Although there is general agreement about the importance of vitamin D for bone health, there remains skepticism about the nonskeletal health benefits of vitamin D. This review will not only focus on the vitamin D deficiency pandemic and ways to treat and prevent vitamin D deficiency but will also explore the epigenetic mechanisms of vitamin D that could help explain many of the nonskeletal benefits of enhancing vitamin D status.

RECENT FINDINGS

The Institute of Medicine and the Endocrine Society have made new recommendations for vitamin D intake to prevent vitamin D deficiency. Vitamin D deficiency is defined as a 25-hydroxyvitamin D level below 20 ng/ml and vitamin D insufficiency is defined as 21-29 ng/ml. Recent observations have suggested that vitamin D can influence epigenetics which may help explain the nonskeletal health benefits that have been reported for vitamin D.

SUMMARY

There is general agreement that vitamin D deficiency is a worldwide health problem. This is due in part to the lack of appreciation that sunlight is an important source of vitamin D. There is no downside to increasing vitamin D intake and recent observations suggesting that vitamin D influences epigenetics provide a new insight for the importance of vitamin D in utero in reducing risk of chronic diseases later in life.

Human growth and chronic disease: a memorial to Jim Tanner

CONTEXT

Memorial to Jim Tanner.

OBJECTIVE

To examine the links between early growth and chronic disease in later life.

METHODS

Literature review.

RESULTS

There is now a developmental model for the origins of chronic disease in which the causes to be identified are linked to normal variations in feto-placental, infant and childhood growth and development. These variations lead to variations in the supply of nutrients to the baby that permanently alters gene expression, a process known as 'programming'.

CONCLUSIONS

Variations in the processes of development programme the function of a few key systems that are linked to chronic disease-the immune system, anti-oxidant defences, inflammatory responses, the number and quality of stem cells, neuro-endocrine settings and the balance of the autonomic nervous system. There is not a separate cause for each different disease. Which chronic disease originates during development may depend more on timing than on qualitative differences in exposures to external influences.

Placental regulation of maternal-fetal interactions and brain development

A variety prenatal insults are associated with the incidence of neurodevelopmental disorders such as schizophrenia, autism and cerebral palsy. While the precise mechanisms underlying how transient gestational challenges can lead to later life dysfunctions are largely unknown, the placenta is likely to play a key role. The literal interface between maternal and fetal cells resides in the placenta, and disruptions to the maternal or intrauterine environment are necessarily conveyed to the developing embryo via the placenta. Placental cells bear the responsibility of promoting maternal tolerance of the semiallogeneic fetus and regulating selective permeability of nutrients, gases, and antibodies, while still providing physiological protection of the embryo from adversity. The placenta's critical role in modulating immune protection and the availability of nutrients and endocrine factors to the offspring implicates its involvement in autoimmunity, growth restriction and hypoxia, all factors associated with the development of neurological complications. In this review, we summarize primary maternal-fetal interactions that occur in the placenta and describe pathways by which maternal insults can impair these processes and disrupt fetal brain development. We also review emerging evidence for placental dysfunction in the prenatal programming of neurodevelopmental disorders.

The immune system and developmental programming of brain and behavior

The brain, endocrine, and immune systems are inextricably linked. Immune molecules have a powerful impact on neuroendocrine function, including hormone-behavior interactions, during health as well as sickness. Similarly, alterations in hormones, such as during stress, can powerfully impact immune function or reactivity. These functional shifts are evolved, adaptive responses that organize changes in behavior and mobilize immune resources, but can also lead to pathology or exacerbate disease if prolonged or exaggerated. The developing brain in particular is exquisitely sensitive to both endogenous and exogenous signals, and increasing evidence suggests the immune system has a critical role in brain development and associated behavioral outcomes for the life of the individual. Indeed, there are associations between many neuropsychiatric disorders and immune dysfunction, with a distinct etiology in neurodevelopment. The goal of this review is to describe the important role of the immune system during brain development, and to discuss some of the many ways in which immune activation during early brain development can affect the later-life outcomes of neural function, immune function, mood and cognition.

Resource allocation in utero and health in later life

The way that a fetus obtains and allocates nutritional resources has profound consequences for its life-long health. Under the new developmental model for the origins of chronic disease, the causes to be identified are linked to normal variations in the processes of feto-placental development, that are associated with differences in the supply of nutrients to the baby. These differences programme the function of a few key systems that are linked to chronic disease, including the immune system, anti-oxidant defences, inflammation, and the number and quality of stem cells. There is not a separate cause for each different disease. Which chronic disease originates during development may depend more on timing than on qualitative differences in experience.

In utero oxidative stress epigenetically programs antioxidant defense capacity and adulthood diseases

SIGNIFICANCE

Maternal health and diet during gestation are critical for predicting fetal outcomes, both immediately at birth and in adulthood. While epigenetic modifications have previously been tightly linked to carcinogenesis, recent advances in the field have suggested that numerous adulthood diseases, including those characteristic of metabolic syndrome, could be programmed in utero in response to maternal exposures, and these "programmable" diseases are associated with epigenetic modifications of vital genes.

RECENT ADVANCES

While little is currently known about the epigenetic regulation of the antioxidant (AOX) defense system, several studies in animals show that AOX defense capacity may be programmed in utero, making it likely that the critical genes involved in this pathway are epigenetically regulated, either by DNA methylation or by the modification of histone tails.

CRITICAL ISSUES

This article presents the most current knowledge of the in utero regulation of the AOX defense capacity, and will specifically focus on the potential epigenetic regulation of this system in response to various in utero exposures or stimuli. The ability to appropriately respond to oxidative stress is critical for the health and survival of any organism, and the potential programming of this capacity may provide a link between the in utero environment and the tendency of certain individuals to be more susceptible toward disease stimuli in their postnatal environments.

FUTURE DIRECTIONS

We sincerely hope that future studies which result in a deeper understanding of the in utero programming of the epigenome will lead to novel and effective therapies for the treatment of epigenetically linked diseases.

Placental size is associated with mental health in children and adolescents

BACKGROUND

The role of the placenta in fetal programming has been recognized as a highly significant, yet often neglected area of study. We investigated placental size in relation to psychopathology, in particular attention deficit hyperactivity disorder (ADHD) symptoms, in children at 8 years of age, and later as adolescents at 16 years.

METHODOLOGY/PRINCIPAL FINDINGS

Prospective data were obtained from The Northern Finland Birth Cohort (NFBC) 1986. Placental weight, surface area and birth weight were measured according to standard procedures, within 30 minutes after birth. ADHD symptoms, probable psychiatric disturbance, antisocial disorder and neurotic disorder were assessed at 8 years (n = 8101), and ADHD symptoms were assessed again at 16 years (n = 6607), by teachers and parents respectively. We used logistic regression analyses to investigate the association between placental size and mental health outcomes, and controlled for gestational age, birth weight, socio-demographic factors and medical factors, during gestation. There were significant positive associations between placental size (weight, surface area and placental-to-birth-weight ratio) and mental health problems in boys at 8 and 16 years of age. Increased placental weight was linked with overall probable psychiatric disturbance (at 8 y, OR= 1.14 [95% CI= 1.04-1.25]), antisocial behavior (at 8 y, OR = 1.14 [95% CI= 1.03-1.27]) and ADHD symptoms (inattention-hyperactivity at 16 y, OR= 1.19 [95% CI = 1.02-1.38]). No significant associations were detected among girls.

CONCLUSIONS/SIGNIFICANCE

Compensatory placental growth may occur in response to prenatal insults. Such overgrowth may affect fetal development, including brain development, and ultimately contribute to psychopathology.

Impaired placental nutrient transport in mice generated by in vitro fertilization

More than 4.5 million children have been conceived by in vitro fertilization (IVF). Interestingly, singleton IVF offspring born at term have an increased incidence of low birth weight. The mechanism responsible for the lower birth weight is unknown, but alterations in placental function are possible. Hence, the goal of our study was to examine placental growth and function in mice generated in vivo or in vitro. To assess placental function, blastocysts were generated by IVF or produced by natural mating (control group); both IVF and control blastocysts were transferred to pseudopregnant recipients. Placental weights did not differ at embryonic d 15.5 (E15.5) but were increased at E18.5 in the IVF group (25.4%, P < 0.001) compared with control. Proliferation was increased in IVF placentae, whereas overall placental gross morphology and apoptosis were not affected. Both fetal weights (16.4% lower at E15.5 and 8.8% lower at E18.5, P < 0.05) and fetal to placental ratios were lower (P < 0.001) in the IVF compared with the control group at both time points, whereas birth weights did not differ. At E18.5, the mRNA for selected glucose, system A amino acid transporters, and imprinted genes were down-regulated in IVF placentae. GLUT3 protein level was decreased in the IVF group (P < 0.05). Importantly, intrajugular injections of (14)C-methyl-D-glucose or (14)C-MeAIB tracers (n = 6 litters per group) showed that placental transport of glucose and amino acids were 24.8% (not significant) and 58.1% (P < 0.05) lower in the IVF group. Fetal accumulation of glucose was not different, but amino acid accumulation was significantly (36 %) lower in IVF fetuses (P < 0.05). We conclude that IVF alters both fetal and placental growth and, importantly, decreases placental transport efficiency in mice conceived by IVF.

Stress-related programming of autonomic imbalance: role in allergy and asthma

Evidence linking psychological stress to allergy has grown with our increased understanding of the natural history and pathophysiology of these disorders and the neurobiology of stress vulnerability. However, the specific pathways that increase vulnerability to developing allergy and associated disorders remain to be elucidated. Autonomic nervous system functioning (autonomic balance) has been implicated in allergy for some time albeit links between autonomic balance and immune function in early development have been under studied. Starting in utero, stress may influence the programming of brain neurotransmitter systems, sympathetic and parasympathetic nervous system functioning, and the hypothalamic-pituitary-adrenal axis, which in turn may alter neural regulation of immune function. Epigenetic dysregulation of gene expression may be a fundamental mechanism for programming of early neural-immune processes.

Molecular mechanisms regulating the vascular prostacyclin pathways and their adaptation during pregnancy and in the newborn

Prostacyclin (PGI(2)) is a member of the prostanoid group of eicosanoids that regulate homeostasis, hemostasis, smooth muscle function and inflammation. Prostanoids are derived from arachidonic acid by the sequential actions of phospholipase A(2), cyclooxygenase (COX), and specific prostaglandin (PG) synthases. There are two major COX enzymes, COX1 and COX2, that differ in structure, tissue distribution, subcellular localization, and function. COX1 is largely constitutively expressed, whereas COX2 is induced at sites of inflammation and vascular injury. PGI(2) is produced by endothelial cells and influences many cardiovascular processes. PGI(2) acts mainly on the prostacyclin (IP) receptor, but because of receptor homology, PGI(2) analogs such as iloprost may act on other prostanoid receptors with variable affinities. PGI(2)/IP interaction stimulates G protein-coupled increase in cAMP and protein kinase A, resulting in decreased [Ca(2+)](i), and could also cause inhibition of Rho kinase, leading to vascular smooth muscle relaxation. In addition, PGI(2) intracrine signaling may target nuclear peroxisome proliferator-activated receptors and regulate gene transcription. PGI(2) counteracts the vasoconstrictor and platelet aggregation effects of thromboxane A(2) (TXA(2)), and both prostanoids create an important balance in cardiovascular homeostasis. The PGI(2)/TXA(2) balance is particularly critical in the regulation of maternal and fetal vascular function during pregnancy and in the newborn. A decrease in PGI(2)/TXA(2) ratio in the maternal, fetal, and neonatal circulation may contribute to preeclampsia, intrauterine growth restriction, and persistent pulmonary hypertension of the newborn (PPHN), respectively. On the other hand, increased PGI(2) activity may contribute to patent ductus arteriosus (PDA) and intraventricular hemorrhage in premature newborns. These observations have raised interest in the use of COX inhibitors and PGI(2) analogs in the management of pregnancy-associated and neonatal vascular disorders. The use of aspirin to decrease TXA(2) synthesis has shown little benefit in preeclampsia, whereas indomethacin and ibuprofen are used effectively to close PDA in the premature newborn. PGI(2) analogs have been used effectively in primary pulmonary hypertension in adults and have shown promise in PPHN. Careful examination of PGI(2) metabolism and the complex interplay with other prostanoids will help design specific modulators of the PGI(2)-dependent pathways for the management of pregnancy-related and neonatal vascular disorders.

Adipose tissue and fetal programming

Adipose tissue function changes with development. In the newborn, brown adipose tissue (BAT) is essential for ensuring effective adaptation to the extrauterine environment, and its growth during gestation is largely dependent on glucose supply from the mother to the fetus. The amount, location and type of adipose tissue deposited can also determine fetal glucose homeostasis. Adipose tissue first appears at around mid-gestation. Total adipose mass then increases through late gestation, when it comprises a mixture of white and brown adipocytes. BAT possesses a unique uncoupling protein, UCP1, which is responsible for the rapid generation of large amounts of heat at birth. Then, during postnatal life some, but not all, depots are replaced by white fat. This process can be utilised to investigate the physiological conversion of brown to white fat, and how it is re-programmed by nutritional changes in pre- and postnatal environments. A reduction in early BAT deposition may perpetuate through the life cycle, thereby suppressing energy expenditure and ultimately promoting obesity. Normal fat development profiles in the offspring are modified by changes in maternal diet at defined stages of pregnancy, ultimately leading to adverse long-term outcomes. For example, excess macrophage accumulation and the onset of insulin resistance occur in an adipose tissue depot-specific manner in offspring born to mothers fed a suboptimal diet from early to mid-gestation. In conclusion, the growth of the different fetal adipose tissue depots varies according to maternal diet and, if challenged in later life, this can contribute to insulin resistance and impaired glucose homeostasis.

Role of the pre- and post-natal environment in developmental programming of health and productivity

The concept that developmental insults (for example, poor pre- or postnatal nutrition) can have long-term consequences on health and well-being of the offspring has been termed developmental programming. In livestock, developmental programming affects production traits, including growth, body composition, and reproduction. Although low birth weight was used as a proxy for compromised fetal development in the initial epidemiological studies, based on controlled studies using livestock and other animal models in the last two decades we now know that developmental programming can occur independently of any effects on birth weight. Studies in humans, rodents, and livestock also have confirmed the critical role of the placenta in developmental programming. In addition, the central role of epigenetic regulation in developmental programming has been confirmed. Lastly, relatively simple therapeutic/management strategies designed to 'rescue' placental development and function are being developed to minimize the effects of developmental programming on health and productivity of humans, livestock, and other mammals.

The prenatal toxic effect of methylmercury on the development of the appendicular skeleton of rat fetuses and the protective role of vitamin E

Methylmercury (MeHg) is an environmental contaminant that is found in many ecosystems. Many studies reported that MeHg toxicity is accompanied by increased lipid peroxidation that may lead to oxidative damage to DNA, RNA, and proteins. Vitamin E is considered as the most effective antioxidant preventing lipid peroxidation. The aim of this study was to evaluate the effects of MeHg exposure during pregnancy on the development of the appendicular skeleton in rat fetuses and whether vitamin E administration could reduce this toxicity. Positively mated adult female Sprague-Dawley rats were used and divided into the following experimental groups: control group, received only deionized water, and four MeHg treated groups received 1 mg of MeHg/kg/d, 2 mg of MeHg/kg/d, 1 mg of MeHg/kg/d plus 150 mg of vitamin E/kg/d, and 2 mg of MeHg/kg/d, plus 150 mg of vitamin E/kg/d starting from Day 0 of gestation. On Day 20 of gestation, the fetuses from the pregnant rats were extracted and the fetal growth parameters were evaluated. Skeletal evaluation of ossification of both fore- and hind-limbs, and coxal bones were undertaken. Results showed that treatment with MeHg caused adverse effects on fetal growth parameters and ossification of the bones. The coadministration of vitamin E with MeHg revealed an improvement in these parameters. These results suggest that vitamin E may ameliorate some aspects of MeHg developmental toxicity. The underlying and human health implications warrant further investigations.

Placental adiponectin gene DNA methylation levels are associated with mothers' blood glucose concentration

Growing evidence suggests that epigenetic profile changes occurring during fetal development in response to in utero environment variations could be one of the mechanisms involved in the early determinants of adult chronic diseases. In this study, we tested whether maternal glycemic status is associated with the adiponectin gene (ADIPOQ) DNA methylation profile in placenta tissue, in maternal circulating blood cells, and in cord blood cells. We found that lower DNA methylation levels in the promoter of ADIPOQ on the fetal side of the placenta were correlated with higher maternal glucose levels during the second trimester of pregnancy (2-h glucose after the oral glucose tolerance test; r(s) ≤ -0.21, P < 0.05). Lower DNA methylation levels on the maternal side of the placenta were associated with higher insulin resistance index (homeostasis model assessment of insulin resistance) during the second and third trimesters of pregnancy (r(s) ≤ -0.27, P < 0.05). Finally, lower DNA methylation levels were associated with higher maternal circulating adiponectin levels throughout pregnancy (r(s) ≤ -0.26, P < 0.05). In conclusion, the ADIPOQ DNA methylation profile was associated with maternal glucose status and with maternal circulating adiponectin concentration. Because adiponectin is suspected to have insulin-sensitizing proprieties, these epigenetic adaptations have the potential to induce sustained glucose metabolism changes in the mother and offspring later in life.

Hypoxanthine-xanthine oxidase down-regulates GLUT1 transcription via SIRT1 resulting in decreased glucose uptake in human placenta

Appropriate foetal growth and development is dependent on adequate placental glucose uptake. Oxidative stress regulates glucose uptake in various tissues. The effect of oxidative stress on placental glucose transport is not known. Thus, the aim of this study was to determine the effect of oxidative stress on glucose uptake and glucose transporters (GLUTs) in human placenta. Human placenta was incubated in the absence or presence of 0.5 mM hypoxanthine+15 mU/ml xanthine oxidase (HX/XO) for 24 h. Gene and protein expressions of the GLUTs were analysed by quantitative RT-PCR and western blotting respectively. Glucose uptake was measured using radiolabelled ((14)C) glucose. HX/XO significantly decreased GLUT1 gene and protein expression and resultant glucose uptake. There was no effect of the antioxidants N-acetylcysteine, catalase and superoxide dismutase or the NF-κB inhibitor BAY 11-0782 on HX/XO-induced decrease in glucose uptake. However, HX/XO treatment significantly decreased both gene and protein expression of SIRT1. In the presence of the SIRT1 activator resveratrol, the decrease in GLUT1 expression and glucose uptake mediated by HX/XO was abolished. Collectively, the data presented here demonstrate that oxidative stress reduces placental glucose uptake and GLUT1 expression by a SIRT1-dependent mechanism.

Multiparity leads to obesity and inflammation in mothers and obesity in male offspring

Multiparity is an independent risk factor for obesity in parous females. In addition to being a health issue for the mother, offspring of multiparous females may also be at risk for obesity later in life. The aim of the current study was to establish a mouse model that mimics the human pathology of multiparity and determine the effects of multiparity-induced obesity (MIO) on offspring in adulthood. C57BL/6 mice were mated and studied when primiparous (1st pregnancy) or multiparous (4th pregnancy). Dams became obese with multiparity, an effect that was independent of the age of the dam. Multiparous dams also had increased markers of inflammation (JNK activation, cytokine expression) in adipose tissue and liver that was greater than inflammation in nulliparous females made obese with a high-fat diet. Placental inflammation was prevalent in multiparous vs. primiparous dams as well. Male offspring of the multiparous dams developed increased adiposity by 24 wk of age relative to the progeny of primiparous dams, although food consumption was similar in both groups. Lipid metabolism was altered in liver and fat in that mRNA levels of regulatory genes (PGC-1α) as well as metabolic genes (CPT I) and Akt phosphorylation were decreased in offspring of multiparous dams. Thus, in mice, as in humans, multiparity increases adiposity and is associated with hepatic and placental inflammation and abnormal glucose tolerance. Importantly, MIO leads to increased body fat and metabolic dysfunction in the offspring, suggesting a role in the propagation of obesity.

Comparison of fresh to fixed weights of the vervet monkey (Chlorocebus sabaeus) placenta and its relation to gestational age

BACKGROUND

Focus on the placenta as an agent of fetal development and offspring health outcomes is growing. Primate research facilities or zoos may collect and fix placental tissue for long-term storage, but little is known about the effects of formalin fixation on the non-human primate placenta.

METHODS

  We obtained 48 vervet monkey placentas from the St. Kitts Biomedical Research Foundation. We investigated via correlation coefficients and ANOVAs the effects of gestational age and original fresh weight on weight change due to fixation. We also used linear regression models to determine whether fixed tissue weight was predictive of fresh weight and gestational age.

RESULTS

Although the vervet monkey placenta is described as bidiscoid, 14.6% of the placentas in this sample were fused into a single mass. A decrease in weight was the most common response to formalin fixation, with the greatest degree of loss experienced by the heaviest placentas (ANOVA, F=5.99, P=0.005). Gestational age was unrelated to weight change. Those placentas that increased in weight had the lowest fresh weights. Fixed weights significantly predicted both fresh weight and gestational age (r(2) =0.78, P<0.00001; r(2) =0.76, P<0.00001, respectively).

CONCLUSIONS

This paper adds to a sparse literature on the vervet monkey placenta. That fixed placentas are excellent predictors of both fresh weight and gestational age suggests that banked tissue may be a valuable resource for reconstructing aspects of individual life history, although caution must be exercised given the variability of weight change as a function of original placental size.

Chronic maternal infusion of full-length adiponectin in pregnant mice down-regulates placental amino acid transporter activity and expression and decreases fetal growth

Maternal adiponectin levels are inversely correlated to birth weight, suggesting that maternal adiponectin limits fetal growth. We hypothesized that full-length adiponectin (fADN) infusion in pregnant mice down-regulates placental amino acid transporters and decreases fetal growth. Starting at embryonic day (E) 14.5, fADN (0.62 ± 0.02 μg (g body weight)(−1) day(−1), n = 7) or vehicle (control, n = 9) were infused in pregnant C57/BL6 mice by mini-osmotic pump. At E18.5, dams were killed and placental homogenates and trophoblast plasma membrane (TPM) vesicles were prepared. Infusion of fADN elevated maternal serum fADN by 4-fold and decreased fetal weights by 18%. Adiponectin receptor 2, but not adiponectin receptor 1, was expressed in TPM. fADN infusion decreased TPM System A (–56%, P < 0.001) and System L amino acid transporter activity (–50%, P < 0.03). TPM protein expression of SNAT1, 2 and 4 (System A amino acid transporter isoforms) and LAT1 and LAT2, but not CD98, (System L amino acid transporter isoforms) was down-regulated by fADN infusion. To identify possible mechanisms underlying these changes we determined the phosphorylation of proteins in signalling pathways known to regulate placental amino acid transporters. fADN decreased phosphorylation of insulin receptor substrate-1 (Tyr-608), Akt (Thr-308 and Ser-473), S6 kinase 1 (Thr-389), eukaryotic initiation factor 4E binding protein 1 (Thr-37/46 and Thr-70) and ribosomal protein S6 (Ser-235/236) and increased the phosphorylation of peroxisome proliferator-activated receptor α (PPARα) (Ser-21) in the placenta. These data suggest that maternal adiponectin decreases fetal growth by down-regulation of placental amino acid transporters, which limits fetal nutrient availability. This effect may be mediated by inhibition of insulin/IGF-I and mTOR signalling pathways, which are positive regulators of placental amino acid transporters. We have identified a novel physiological mechanism by which the endocrine functions of maternal adipose tissue influence fetal growth.

Review: Placenta, evolution and lifelong health

The intrauterine environment has an important influence on lifelong health, and babies who grew poorly in the womb are more likely to develop chronic diseases in later life. Placental function is a major determinant of fetal growth and is therefore also a key influence on lifelong health. The capacity of the placenta to transport nutrients to the fetus and regulate fetal growth is determined by both maternal and fetal signals. The way in which the placenta responds to these signals will have been subject to evolutionary selective pressures. The responses selected are those which increase Darwinian fitness, i.e. reproductive success. This review asks whether in addition to responding to short-term signals, such as a rise in maternal nutrient levels, the placenta also responds to longer-term signals representing the mother's phenotype as a measure of environmental influences across her life course. Understanding how the placenta responds to maternal signals is therefore not only important for promoting optimal fetal growth but can also give insights into how human evolution affected developmental history with long-term effects on health and disease.

The role of oxidative stress in the pathophysiology of gestational diabetes mellitus

Normal human pregnancy is considered a state of enhanced oxidative stress. In pregnancy, it plays important roles in embryo development, implantation, placental development and function, fetal development, and labor. However, pathologic pregnancies, including gestational diabetes mellitus (GDM), are associated with a heightened level of oxidative stress, owing to both overproduction of free radicals and/or a defect in the antioxidant defenses. This has important implications on the mother, placental function, and fetal well-being. Animal models of diabetes have confirmed the important role of oxidative stress in the etiology of congenital malformations; the relative immaturity of the antioxidant system facilitates the exposure of embryos and fetuses to the damaging effects of oxidative stress. Of note, there are only a few clinical studies evaluating the potential beneficial effects of antioxidants in GDM. Thus, whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus needs to be explored. This review provides an overview and updated data on our current understanding of the complications associated with oxidative changes in GDM.

Effects of APOA5 S19W polymorphism on growth, insulin sensitivity and lipoproteins in normoweight neonates

Apolipoprotein (Apo) A5 is a protein involved in the activation of lipoprotein lipase (LPL) and the metabolism of triglyceride (TG)-rich lipoproteins. LPL plays a major role in the metabolism of TG-rich lipoproteins, and placental LPL activity is known to correlate positively with foetal fat deposition and size. We examine the association between the common APOA5 S19W polymorphism and neonatal anthropometrical measurements, lipoprotein and hormone concentrations, and insulin sensitivity in 58 normal weight Caucasian newborns from the Mérida cohort. Neonates with the W allele displayed lower BMI (P < 0.001), ponderal index (P < 0.001), birth weight (P < 0.01), insulin levels (P < 0.05), the insulin/cortisol ratio (P < 0.05), HOMA-R (P < 0.05) and Apo B values (P < 0.01), but higher oxidised LDL (LDLox) values and a higher LDLox/low-density lipoprotein (LDL) ratio (both P < 0.05) than S-homozygous newborns. The APOA5 S19W polymorphism was associated with foetal growth as well as with glucose and lipoprotein metabolism in the neonates. Concurrence of the S19W polymorphism in neonates and their mothers did not affect neonatal lipid and lipoprotein concentrations but was associated with impaired foetal growth. Specifically, W allele carriers displayed a higher degree of LDL oxidation and lower body weight, plasma insulin values, insulin/cortisol ratio and Apo B concentrations than homozygotes for the common S allele. In conclusion, these findings suggest that the W allele carriers received a less optimal nutrition during gestation and that their lipoprotein antioxidant status was inferior to that of their homozygous S allele counterparts.

Blood Ferritin Levels in Pregnant Women and Prediction of the Development of Fetal Intrauterine Growth Restriction

Intrauterine growth restriction is one of the leading causes of perinatal morbidity and mortality. Prediction of intrauterine growth restriction is one of the priority tasks of perinatal protection. The purpose of this study was to evaluate the levels of serum ferritin in pregnant women, which could point to a group of patients in whom possible development of fetal growth restriction could have been expected. In this investigation, we conducted a prospective study of healthy pregnant women between 30 and 32 gestational weeks, who were estimated for ferritin values. Newborn infants of low birth weight for gestational age were recorded in 8.1%. Anemia was not present in any of the patients who delivered low birth weight babies. Ferritin serum levels in mothers of the babies with low birth weight were on average 6.42 μg/L higher than in the mothers with appropriate for gestational age babies (p<0.005). ROC analysis of newborn infants birth weight and maternal blood ferritin levels showed that blood ferritin level had good predictive value. In case the recorded maternal blood ferritin values are above 13.6 μg/L, we can assume with the sensitivity of 64.7% and specificity of 91.7%, that the pregnant woman will develop a condition of intrauterine growth restriction. The missing decrease of ferritin values, erythrocytes, hemoglobin and hematocrit in the blood of healthy pregnant women between 30 and 32 gestational weeks, can with high probability point to the development of fetal intrauterine growth restriction.

Salivary cortisol in pregnant women suffering from blood and injection phobia

Stress and/or anxiety during pregnancy affect maternal and fetal well-being and can cause premature delivery and postnatal pathology in the child. Women suffering from phobias related to blood and injections are prone to high levels of stress, including anxiety and sometimes panic attacks, during pregnancy. Cortisol is amongst the mediators through which the neurohormonal expressions of maternal psychological factors may be transduced to the fetus. The aim of this study was to investigate whether pregnant women suffering from blood and injection phobia have raised cortisol levels or are characterized by unusual diurnal salivary cortisol profiles compared with healthy controls. The sample consisted of 110 pregnant women with blood and injection phobia and 110 pregnant healthy controls. Both groups provided morning and evening saliva samples in weeks 25 and 36 for the assay of cortisol. In gestational week 25, when blood was drawn for the mandatory blood testing, extra blood was taken to analyze corticotrophin-releasing factor, adrenocorticotropic hormone, and cortisol in serum. The diurnal decline in salivary cortisol as well as increased cortisol levels were observed during pregnancy. Pregnant women suffering from blood and injection phobia had a higher output of cortisol compared with women without the phobia (F = 6.25, df = 1, p = 0.014), but no marked difference in the diurnal cortisol rhythm was found between groups. Our findings indicate that untreated blood and injection phobia during pregnancy increases cortisol concentrations. Blood and injection phobia is treatable, and cognitive behavioral therapy can be used. Women with blood and injection phobia during pregnancy therefore need to be recognized and offered treatment without delay in early pregnancy.

Placental vascular dysfunction in diabetic pregnancies: intimations of fetal cardiovascular disease?

In the human placenta, the angioarchitecture of fetal vessels lying in maternal blood is useful for nutrient uptake, but it makes the synthesis, maturation and functioning of placental vessels vulnerable to any alterations in the fetal and maternal environment. This review discusses how the maternal diabetic milieu, and the resultant fetal hyperglycemia and hyperinsulinemia, may act together to produce an altered placental vascular phenotype, which includes increased angiogenesis, altered junctional maturity, increased vascular endothelial-like growth factor (VEGF), altered VEGF and insulin receptor profiles, and upregulation of genes involved in signal transduction, transcription and mitosis in placental endothelial cells. The placental vascular dysfunction does extend to other fetal vascular beds including endothelial cells from umbilical vessels, where there are reports of elevated basal iNOS activity and altered sensitivity to insulin. There is emerging evidence of epigenetic modulation of fetal endothelial genes in diabetes and long-term vascular consequences of this. Thus, placental vascular dysfunction in diabetes may be contributing to and describing disturbances in the fetal vasculature, which may produce an overt pathological response in later life if challenged with additional cardiovascular stresses.

Mother's lifetime nutrition and the size, shape and efficiency of the placenta

BACKGROUND

Studies have shown that the shape and size of the placenta at birth predict blood pressure in later life. The influences that determine placental morphology are largely unknown. We have examined the role of mother's body size.

METHODS

We studied 522 neonates who were born in a maternity hospital in Mysore, South India. The weight of the placenta and the length and breadth of its surface, were measured after delivery.

RESULTS

Higher maternal fat mass predicted a larger placental surface (p = 0.02), while larger maternal head circumference predicted a more oval placental surface (p = 0.03). Higher maternal fat mass and larger maternal head circumference were associated with greater placental efficiency, indicated by lower ratios of the length (p = 0.0003 and p = 0.0001 respectively) and breadth (p = 0.0002 and p < 0.0001) of the surface to birthweight. In a sub-sample of 51 mothers whose own birthweight was available, higher maternal birthweight was related to lower ratios of the length and breadth of the surface to birthweight (p = 0.01 and 0.002). Maternal height was unrelated to placental size or shape.

CONCLUSIONS

Higher maternal fat mass, reflecting the mother's current nutritional state, and larger maternal head circumference, reflecting the mother's fetal/infant growth, are associated with changes in the shape and size of the placental surface and greater placental efficiency. We suggest that these associations reflect effects of the mother's nutrition at different stages of her lifecourse on the development of the placenta and on materno-placento-fetal transfer of nutrients.

Nutritionally mediated programming of the developing immune system

A growing body of evidence highlights the importance of a mother's nutrition from preconception through lactation in programming the emerging organ systems and homeostatic pathways of her offspring. The developing immune system may be particularly vulnerable. Indeed, examples of nutrition-mediated immune programming can be found in the literature on intra-uterine growth retardation, maternal micronutrient deficiencies, and infant feeding. Current models of immune ontogeny depict a "layered" expansion of increasingly complex defenses, which may be permanently altered by maternal malnutrition. One programming mechanism involves activation of the maternal hypothalamic-pituitary-adrenal axis in response to nutritional stress. Fetal or neonatal exposure to elevated stress hormones is linked in animal studies to permanent changes in neuroendocrine-immune interactions, with diverse manifestations such as an attenuated inflammatory response or reduced resistance to tumor colonization. Maternal malnutrition may also have a direct influence, as evidenced by nutrient-driven epigenetic changes to developing T regulatory cells and subsequent risk of allergy or asthma. A 3rd programming pathway involves placental or breast milk transfer of maternal immune factors with immunomodulatory functions (e.g. cytokines). Maternal malnutrition can directly affect transfer mechanisms or influence the quality or quantity of transferred factors. The public health implications of nutrition-mediated immune programming are of particular importance in the developing world, where prevalent maternal undernutrition is coupled with persistent infectious challenges. However, early alterations to the immune system, resulting from either nutritional deficiencies or excesses, have broad relevance for immune-mediated diseases, such as asthma, and chronic inflammatory conditions like cardiovascular disease.

Reduced levels of placental long chain polyunsaturated fatty acids in preterm deliveries

Reports suggest that the placenta in preterm birth may provide clues to predicting the risk of individuals developing chronic diseases in later life. Placental delivery of long chain polyunsaturated fatty acids (LCPUFA) (constituents of the cell membrane and precursors of prostaglandins) is essential for the optimal development of the central nervous system of the fetus. The present study examines the levels of LCPUFA and their association with placental weight and birth outcome in 58 women delivering preterm and 44 women delivering at term. Docosahexaenoic acid (DHA) and arachidonic acid (ARA) levels were lower (p<0.01) in women delivering preterm. There was a positive association of placental DHA with placental weight (p=0.036) and nervonic acid with head circumference (p=0.040) in the preterm group. Altered placental LCPUFA status exists in Indian mothers delivering preterm, which may influence the birth outcome.

11β-Hydroxysteroid dehydrogenase type 1 activity in short small-for-GA children and in response to GH therapy

Small for GA (SGA) children are at risk for developing the metabolic syndrome. Those who do not catch up, and remain short (SSGA), may benefit from GH therapy. 11β Hydroxysteroid dehydrogenase type 1 (11β-HSD-1) is expressed in visceral fat and is implicated in metabolic morbidity. We hypothesized that SSGA children will have increased basal and glucocorticoid (GC)-stimulated 11β-HSD-1 activity. Twenty SSGA children, aged 7.1 ± 1 y (mean ± SD), were studied before and while on GH therapy and compared with 12 normal age-matched controls. 11β-HSD-1 activity was evaluated by gas chromatography mass spectrometry (GCMS) of urinary steroid product/substrate ratios. GC-stimulated 11β-HSD-1 activity was assessed after overnight dexamethazone (DEX), by oral cortisone conversion to cortisol. In SSGA children, 11β-HSD-1 activity was lower (p < 0.05) and GC-stimulated activity enhanced. SSGA children had maximal cortisol generation of 883 ± 108 compared with 690 ± 63 nmol/L in controls (p < 0.04). GH treatment suppressed 11β-HSD-1 activity. GC-stimulated enzyme activity correlated negatively with GA (r = -0.53, p < 0.01) and birth weight (r = -0.55, p < 0.01). SSGA is associated with enhanced GC-stimulated 11β-HSD-1 activity. This may be programmed in utero, as it is not a function of body composition or secondary metabolic derangement. GH therapy normalizes GC-stimulated 11β-HSD-1 activity.

Placental dysfunction and fetal programming: the importance of placental size, shape, histopathology, and molecular composition

Normal function of the placenta is pivotal for optimal fetal growth and development. Fetal programming commonly is associated with placental dysfunction that predisposes to obstetric complications and suboptimal fetal outcomes. We consider several clinical phenotypes for placental dysfunction that likely predispose to fetal programming. Some of these reflect abnormal development of the chorioallantoic placenta in size, shape, or histopathology. Others result when exogenous stressors in the maternal environment combine with maladaptation of the placental response to yield small placentas with limited reserve, as typical of early-onset intrauterine growth restriction and preeclampsia. Still others reflect epigenetic changes, including altered expression of imprinted genes, altered enzymatic activity, or altered efficiencies in nutrient transport. Although the human placenta is a transient organ that persists only 9 months, the effects of this organ on the offspring remain for a lifetime.

Development and function of the human fetal adrenal cortex: a key component in the feto-placental unit

Continuous efforts have been devoted to unraveling the biophysiology and development of the human fetal adrenal cortex, which is structurally and functionally unique from other species. It plays a pivotal role, mainly through steroidogenesis, in the regulation of intrauterine homeostasis and in fetal development and maturation. The steroidogenic activity is characterized by early transient cortisol biosynthesis, followed by its suppressed synthesis until late gestation, and extensive production of dehydroepiandrosterone and its sulfate, precursors of placental estrogen, during most of gestation. The gland rapidly grows through processes including cell proliferation and angiogenesis at the gland periphery, cellular migration, hypertrophy, and apoptosis. Recent studies employing modern technologies such as gene expression profiling and laser capture microdissection have revealed that development and/or function of the fetal adrenal cortex may be regulated by a panoply of molecules, including transcription factors, extracellular matrix components, locally produced growth factors, and placenta-derived CRH, in addition to the primary regulator, fetal pituitary ACTH. The role of the fetal adrenal cortex in human pregnancy and parturition appears highly complex, probably due to redundant and compensatory mechanisms regulating these events. Mounting evidence indicates that actions of hormones operating in the human feto-placental unit are likely mediated by mechanisms including target tissue responsiveness, local metabolism, and bioavailability, rather than changes only in circulating levels. Comprehensive study of such molecular mechanisms and the newly identified factors implicated in adrenal development should help crystallize our understanding of the development and physiology of the human fetal adrenal cortex.

Low amino acids affect expression of 11β-HSD2 in BeWo cells through leptin-activated JAK-STAT and MAPK pathways

Maternal protein restriction diminishes placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) activity and causes fetal growth restriction in mammals. However, it is unknown whether such effect was caused directly by nutrient deficiency, or indirectly through the mediation of maternal hormones. In the present study, a human placental cell line (BeWo) was cultured in F12K as control and F12 as low amino acids (LAA) media for 48 h to investigate the effects of amino acids deficiency on 11β-HSD2 expression and activity. Despite a significant up-regulation of 11β-HSD2 mRNA expression in LAA cells, 11β-HSD2 activity and protein content were decreased by 38 and 54%, respectively (P<0.05), indicating a mechanism of post-transcriptional regulation. Among 5 miRNAs targeting 11β-HSD2, miR-498 was expressed significantly higher in LAA cells. Leptin concentration was significantly lower (P<0.01) in LAA medium. The mRNA expression of both isoforms of leptin receptor was significantly higher in LAA cells, although no difference was detected at protein level. To further clarify whether leptin is involved in mediating the effect of LAA on 11β-HSD2 activity, leptin was supplemented to LAA medium, whereas three specific inhibitors of leptin signaling pathways, WP1066 for JAK-STAT, PD98059 for MAPK and LY294002 for PI3K, respectively were added to control medium. Leptin restored the diminished 11β-HSD2 activity in LAA cells, whereas WP1066 (5 nM) and PD98059 (50 nM) significantly decreased 11β-HSD2 activity in control cells. In conclusion, the present results indicate that LAA diminishes 11β-HSD2 expression and activity in BeWo cells through leptin-activated JAK-STAT and MAPK pathways.