Placental contribution to the origins of sexual dimorphism in health and diseases: sex chromosomes and epigenetics

Sexually Dimorphic Impact of Chromium Accumulation on Human Placental Oxidative Stress and Apoptosis

Environmental contamination with hexavalent chromium (CrVI) is a growing problem both in the United States and developing countries. Hexavalent chromium is widely used in numerous industries. Environmental exposure to CrVI adversely affects pregnancy outcomes and subsequent health of 2 generations, resulting in higher pregnancy loss, spontaneous abortion and low birth rate. Pregnant women exposed to CrVI through occupational settings experience increased risk of spontaneous abortion, stillbirth, preterm birth, and neonatal death. Children of the CrVI exposed women experience respiratory problems, perinatal jaundice, and increased birth defects. Because placental dysfunction may have a role in such adverse pregnancy outcome, we tested the hypothesis that environmental Cr exposure in pregnant women results in Cr accumulation in the human placenta, which could increase placental oxidative stress by disrupting antioxidant machinery and inducing apoptosis. Studies using frozen, deidentified human term placenta samples indicated that: (1) Cr accumulates in human term placenta tissues and (2) increase in Cr accumulation is positively correlated with oxidative stress and apoptotic markers, and altered antioxidants levels. Interestingly, there was a sexual dimorphism in the correlation between Cr accumulation and oxidative stress, and expression of apoptotic and antioxidant markers. Mechanistic in vitro studies using human trophoblast cells BeWo confirmed the detrimental effects of Cr in altering antioxidant genes. For the first time, this study provides evidence in support of a positive correlation between Cr accumulation in the human placenta and accelerated oxidative stress, with a gender bias toward the male sex.

Neuroinflammation in preterm babies and autism spectrum disorders

Genetic anomalies have a role in autism spectrum disorders (ASD). Each genetic factor is responsible for a small fraction of cases. Environment factors, like preterm delivery, have an important role in ASD. Preterm infants have a 10-fold higher risk of developing ASD. Preterm birth is often associated with maternal/fetal inflammation, leading to a fetal/neonatal inflammatory syndrome. There are demonstrated experimental links between fetal inflammation and the later development of behavioral symptoms consistent with ASD. Preterm infants have deficits in connectivity. Most ASD genes encode synaptic proteins, suggesting that ASD are connectivity pathologies. Microglia are essential for normal synaptogenesis. Microglia are diverted from homeostatic functions towards inflammatory phenotypes during perinatal inflammation, impairing synaptogenesis. Preterm infants with ASD have a different phenotype from term born peers. Our original hypothesis is that exposure to inflammation in preterm infants, combined with at risk genetic background, deregulates brain development leading to ASD.

Prenatal Risk for ASD: Fetal Cortisol Exposure Predicts Child Autism-Spectrum Disorder Symptoms

The etiology of autism spectrum disorder (ASD) is multifactorial and complex and likely involves interactions among genetic, epigenetic and environmental factors. With respect to environmental influences, a growing literature implicates intrauterine experiences in the origin of this pervasive developmental disorder. In this prospective longitudinal design, we examine the hypothesis that fetal exposure to maternal cortisol may confer ASD risk. In addition, because ASD is four times more prevalent in males than females and because sexually dimorphic responses to intrauterine experiences are commonly observed, we examine whether or not any associations differ by fetal sex. Maternal plasma cortisol was measured at 15, 19, 25, 31, and 37 weeks' gestation in a sample of 84 pregnant women. ASD symptoms were assessed in their 5-year old children with the Social Communication Questionnaire (SCQ). Fetal exposure to lower levels of maternal cortisol was associated with higher levels of ASD symptoms among boys only. The observed hypocortisolemic profile exhibited by these mothers may indicate a risk factor that precedes the stress of caregiving for a child with ASD and may not be solely a consequence of the stress of caregiving as previously thought. Further, these findings confirm the value of examining prenatal hormone exposures as predictors of ASD risk and support the premise that altered prenatal steroid exposures may play a role in the etiology of ASD.

Absence of Intestinal Microbiota during Gestation and Lactation Does Not Alter the Metabolic Response to a Western-type Diet in Adulthood

SCOPE

Microbiota composition in early life is implied to affect the risk to develop obesity in adulthood. It is unclear whether this risk is due to long-lasting microbiome-induced changes in host metabolism. This study aims to identify whether the presence or total absence of early-life microbiota affects host metabolism in adulthood.

METHODS AND RESULTS

The effects of a germ-free (Former GF) versus conventional status during gestation and lactation on the metabolic status in adult offspring are compared. Upon conventionalization at weaning, all mice were metabolically challenged with a Western-type diet (WTD) at 10 weeks age. Between age 10 and 30 weeks, a former GF status does not notably affect overall body weight gain, cholesterol metabolism, glucose tolerance or insulin sensitivity at adult age. However, Former GF mice have lower bile flow and bile acid secretion in adulthood, but similar bile acid composition.

CONCLUSIONS

A germ-free status during gestation and lactation does not substantially affect key parameters of the metabolic status before 10 weeks of age on chow diet or in adulthood following a WTD challenge. These data imply that microbiota in early life does not critically affect adult metabolic plasticity.

Exposure to maternal obesity alters gene expression in the preimplantation ovine conceptus

Background

Embryonic and fetal exposure to maternal obesity causes several maladaptive morphological and epigenetic changes in exposed offspring. The timing of these events is unclear, but changes can be observed even after a short exposure to maternal obesity around the time of conception. The hypothesis of this work is that maternal obesity influences the ovine preimplantation conceptus early in pregnancy, and this exposure will affect gene expression in embryonic and extraembryonic tissues.

Results

Obese and lean ewe groups were established by overfeeding or normal feeding, respectively. Ewes were then bred to genetically similar rams. Conceptuses were collected at day 14 of gestation. Morphological assessments were made, conceptuses were sexed by genomic PCR analysis, and samples underwent RNA-sequencing analysis. While no obvious morphological differences existed between conceptuses, differentially expressed genes (≥ 2-fold; ≥ 0.2 RPKM; ≤ 0.05 FDR) were detected based on maternal obesity exposure (n = 21). Also, differential effects of maternal obesity were noted on each conceptus sex (n = 347). A large portion of differentially expressed genes were associated with embryogenesis and placental development.

Conclusions

Findings reveal that the preimplantation ovine conceptus genome responds to maternal obesity in a sex-dependent manner. The sexual dimorphism in response to the maternal environment coupled with changes in placental gene expression may explain aberrations in phenotype observed in offspring derived from obese females.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5120-0) contains supplementary material, which is available to authorized users.

Maternal high fat diet alters offspring epigenetic regulators, amygdala glutamatergic profile and anxiety

Maternal obesity during pregnancy can impact long-term health, predisposition to disease, and risk of neurological disorders in offspring. This may arise from disruption to epigenetic processes during offspring brain development. Using a maternal high fat diet (mHFD) mouse model, we investigated the expression of genes encoding epigenetic regulators in the brains of gestational day (GD) 17.5 mHFD offspring. We found significant, regionally unique changes in expression of epigenetic regulators in the developing brain of mHFD offspring compared to controls, with Gadd45b downregulated in medial prefrontal cortex, Mecp2 downregulated in amygdala, and sex-specific downregulation of Crebbp, Dnmt3b, and Mecp2 in male mHFD hippocampus. Decreased Mecp2 in the amygdala was associated with significant upregulation of the Mecp2-repressed gene, Tbr1, and an increased number of TBR1⁺ glutamatergic neurons in the basomedial nucleus of the amygdala. Tbr1 upregulation in amygdala was also observed in postnatal day 8 (P8) mHFD offspring, and levels of glutamate receptor gene Grin2b, and Fos, a marker for neuronal activity, were increased. Indications of heightened excitatory drive in mHFD offspring amygdala were associated with an anxiety-like phenotype, with mHFD offspring displaying altered ultrasonic vocalization characteristics at P8, and adult female mHFD offspring spending decreased time on the open arm of the Elevated Plus Maze. Together, this data provides insight into sex-specific offspring vulnerability to perinatal mHFD programming of anxiety-like behaviors.

Low-dose developmental bisphenol A exposure alters fatty acid metabolism in Fischer 344 rat offspring

BACKGROUND

Bisphenol A (BPA) is an endocrine disruptor and also a suggested obesogen and metabolism-disrupting chemical. Accumulating data indicates that the fatty acid (FA) profile and their ratios in plasma and other metabolic tissues are associated with metabolic disorders. Stearoyl-CoA desaturase 1 (SCD-1) is a key regulator of lipid metabolism and its activity can be estimated by dividing the FA product by its precursor measured in blood or other tissues.

OBJECTIVE

The primary aim of this study was to investigate the effect of low-dose developmental BPA exposure on tissue-specific FA composition including estimated SCD-1 activity, studied in 5- and 52-week (wk)-old Fischer 344 (F344) rat offspring.

METHODS

Pregnant F344 rats were exposed to BPA via their drinking water corresponding to 0: [CTRL], 0.5: [BPA0.5], or 50 µg/kg BW/day: [BPA50], from gestational day 3.5 until postnatal day 22.

RESULTS

BPA0.5 increased SCD-16 (estimated as the 16:1n-7/16:0 ratio) and SCD-18 (estimated as the 18:1n-9/18:0 ratio) indices in inguinal white adipose tissue triglycerides (iWAT-TG) and in plasma cholesterol esters (PL-CE), respectively, in 5-wk-old male offspring. In addition, BPA0.5 altered the FA composition in male offspring, e.g. by decreasing levels of the essential polyunsaturated FA linoleic acid (18:2n-6) in iWAT-and liver-TG. No differences were observed regarding the studied FAs in 52-wk-old offspring, although a slightly increased BW was observed in 52-wk-old female offspring.

CONCLUSIONS

Low-dose developmental BPA exposure increased SCD-16 in iWAT-TG and SCD-18 in PL-CE of male offspring, which may reflect higher SCD-1 activity in these tissues. Altered desaturation activity and signs of altered FA composition are novel findings that may indicate insulin resistance in the rat offspring. These aforementioned results, together with the observed increased BW, adds to previously published data demonstrating that BPA can act as a metabolism disrupting chemical.

Sex Differences in Vulnerability to Prenatal Stress: a Review of the Recent Literature

PURPOSE OF REVIEW

To evaluate the degree to which recent studies provide evidence that the effects of prenatal maternal stress (PNMS) on child health outcomes vary depending on the child's biological sex. In this review, we used a broad definition of stress, including negative life events, psychological stress, and established stress biomarkers. We identified 50 peer-reviewed articles (published January 2015-December 2017) meeting the inclusion criteria.

RECENT FINDINGS

Most articles (k = 35) found evidence of either sex-specific associations (significant in one sex but not the other) or significant PNMSxstress interactions for at least one child health outcome. Evidence for sex-dependent effects was strongest in the group of studies evaluating child neural/nervous system development and temperament as outcomes. There is sufficient evidence of sex-dependent associations to recommend that researchers always consider the potential role of child sex in PNMS programming studies and report descriptive statistics for study outcomes stratified by child biological sex.

Gender disparities in preterm neonatal outcomes

AIM

From birth to old age, males generally have poorer disease outcomes compared to females. Preterm infants display a marked gender disparity in disease outcomes, and the underlying mechanisms are not well delineated. Our aim was to review the literature on clinical outcomes between preterm infants of different genders and discuss the potential mechanisms underlying the differences observed.

METHODS

A literature review was undertaken for experimental and clinical research related to gender differences in preterm outcomes.

RESULTS

Preterm male infants appear to have consistently worse outcomes compared to females, and the aetiology of these differences, while mostly undetermined, is likely multifactorial.

CONCLUSION

The male disadvantage in preterm outcomes is likely multifactorial with hormonal, genetic and immunological differences likely playing key roles. Gender is an important variable in preterm outcome and should be considered when designing clinical and experimental research.

Exercise in pregnancy: 1-year and 7-year follow-ups of mothers and offspring after a randomized controlled trial

There are limited data on long-term outcomes of mothers or their offspring following exercise interventions during pregnancy. We assessed long-term effects of an exercise intervention (home-based stationary cycling) between 20–36 weeks of gestation on anthropometry and body composition in mothers and offspring after 1 and 7 years. 84 women were randomised to intervention or usual activity, with follow-up data available for 61 mother-child pairs (38 exercisers) at 1 year and 57 (33 exercisers) at 7 years. At 1 year, there were no observed differences in measured outcomes between mothers and offspring in the two groups. At the 7-year follow-up, mothers were mostly similar, except that exercisers had lower systolic blood pressure (−6.2 mmHg; p = 0.049). However, offspring of mothers who exercised during pregnancy had increased total body fat (+3.2%; p = 0.034) and greater abdominal (+4.1% android fat; p = 0.040) and gynoid (+3.5% gynoid fat; p = 0.042) adiposity compared with controls. Exercise interventions beginning during pregnancy may be beneficial to long-term maternal health. However, the initiation of exercise during pregnancy amongst sedentary mothers may be associated with adverse effects in the offspring during childhood. Larger follow-up studies are required to investigate long-term effects of exercise in pregnancy.

Folate treatment of pregnant rat dams abolishes metabolic effects in female offspring induced by a paternal pre-conception unhealthy diet

AIMS/HYPOTHESIS

Paternal high-fat diet prior to mating programmes impaired glucose tolerance in female offspring. We examined whether the metabolic consequences in offspring could be abolished by folate treatment of either the male rats before mating or the corresponding female rats during pregnancy.

METHODS

Male F0 rats were fed either control diet or high-fat, high-sucrose and high-salt diet (HFSSD), with or without folate, before mating. Male rats were mated with control-diet-fed dams. After mating, the F0 dams were fed control diet with or without folate during pregnancy.

RESULTS

Male, but not female offspring of HFSSD-fed founders were heavier than those of control-diet-fed counterparts (p < 0.05 and p = 0.066 in males and females, respectively). Both male and female offspring of HFSSD-fed founders were longer compared with control (p < 0.01 for both sexes). Folate treatment of the pregnant dams abolished the effect of the paternal diet on the offspring's body length (p ˂ 0.05). Female offspring of HFSSD-fed founders developed impaired glucose tolerance, which was restored by folate treatment of the dams during pregnancy. The beta cell density per pancreatic islet was decreased in offspring of HFSSD-fed rats (-20% in male and -15% in female F1 offspring, p ˂ 0.001 vs controls). Folate treatment significantly increased the beta cell density (4.3% and 3.3% after folate supplementation given to dams and founders, respectively, p ˂ 0.05 vs the offspring of HFSSD-fed male rats). Changes in liver connective tissue of female offspring of HFSSD-fed founders were ameliorated by treatment of dams with folate (p ˂ 0.01). Hepatic Ppara gene expression was upregulated in female offspring only (1.51-fold, p ˂ 0.05) and was restored in the female offspring by folate treatment (p ˂ 0.05). We observed an increase in hepatic Lcn2 and Tmcc2 expression in female offspring born to male rats exposed to an unhealthy diet during spermatogenesis before mating (p ˂ 0.05 vs controls). Folate treatment of the corresponding dams during pregnancy abolished this effect (p ˂ 0.05). Analysis of DNA methylation levels of CpG islands in the Ppara, Lcn2 and Tmcc2 promoter regions revealed that the paternal unhealthy diet induced alterations in the methylation pattern. These patterns were also affected by folate treatment. Total liver DNA methylation was increased by 1.52-fold in female offspring born to male rats on an unhealthy diet prior to mating (p ˂ 0.05). This effect was abolished by folate treatment during pregnancy (p ˂ 0.05 vs the offspring of HFSSD-fed male rats).

CONCLUSIONS/INTERPRETATION

Folate treatment of pregnant dams restores effects on female offspring's glucose metabolism induced by pre-conception male founder HFSSD.

Time- and sex-dependent associations between prenatal alcohol exposure and placental global DNA methylation

AIM

Epigenetic changes, in particular in the placenta, may mediate the effects of prenatal alcohol exposure (PAE) on children's health. We examined the relationship between PAE patterns, based on dose and timing, and placental global DNA methylation.

METHODS

Using linear regression analysis, we examined the association between different PAE categories and placental global DNA methylation (n = 187), using the proxy measure of Alu-interspersed repeats.

RESULTS

Following adjustment for important covariates, we found no evidence of an association between PAE and placental global DNA methylation overall. However, when stratifying by newborn sex, PAE throughout pregnancy was associated with higher placental global DNA methylation (1.5%; p = 0.01) of male newborns.

CONCLUSION

PAE may have sex-specific effects on placental global DNA methylation if alcohol is consumed throughout pregnancy.

Sex Differences in Early Embryogenesis: Inter-Chromosomal Regulation Sets the Stage for Sex-Biased Gene Networks: The dialogue between the sex chromosomes and autosomes imposes sexual identity soon after fertilization

Sex-specific transcriptional and epigenomic profiles are detectable in the embryo very soon after fertilization. I propose that in male (XY) and female (XX) pre-implantation embryos sex chromosomes establish sexually dimorphic interactions with the autosomes, before overt differences become apparent and long before gonadogenesis. Lineage determination restricts expression biases between the sexes, but the epigenetic differences are less constrained and can be perpetuated, accounting for dimorphisms that arise later in life. In this way, sexual identity is registered in the epigenome very early in development. As development progresses, sex-specific regulatory modules are harbored within shared transcriptional networks that delineate common traits. In reviewing this field, I propose that analyzing the mechanisms for sexual dimorphisms at the molecular and biochemical level and incorporating developmental and environmental factors will lead to a greater understanding of sex differences in health and disease. Also see the video abstract here: https://youtu.be/9BPlbrHtkHQ.

Prenatal Maternal Cortisol Has Sex-Specific Associations with Child Brain Network Properties

Elevated maternal cortisol concentrations have the potential to alter fetal development in a sex-specific manner. Female brains are known to show adaptive behavioral and anatomical flexibility in response to early-life exposure to cortisol, but it is not known how these sex-specific effects manifest at the whole-brain structural networks. A prospective longitudinal study of 49 mother child dyads was conducted with serial assessments of maternal cortisol levels from 15 to 37 gestational weeks. We modeled the structural network of typically developing children (aged 6-9 years) and examined its global connectome properties, rich-club organization, and modular architecture. Network segregation was susceptible only for girls to variations in exposure to maternal cortisol during pregnancy. Girls generated more connections than boys to maintain topologically capable and efficient neural circuits, and this increase in neural cost was associated with higher levels of internalizing problems. Maternal cortisol concentrations at 31 gestational weeks gestation were most strongly associated with altered neural connectivity in girls, suggesting a sensitive period for the maternal cortisol-offspring brain associations. Our data suggest that girls exhibit an adaptive response by increasing the neural network connectivity necessary for maintaining homeostasis and efficient brain function across the lifespan.

Sex differences in umbilical artery Doppler indices: a longitudinal study

Background

Sexual dimorphism in placental size and function has been described. Whether this influences the clinically important umbilical artery (UA) waveform remains controversial, although a few cross-sectional studies have shown sex differences in UA pulsatility index (PI). Therefore, we tested whether fetal sex influences the UA Doppler indices during the entire second half of pregnancy and aimed to establish sex-specific reference ranges for UA Doppler indices if needed.

Methods

Our main objective was to investigate gestational age-associated changes in UA Doppler indices during the second half of pregnancy and compare the values between male and female fetuses. This was a prospective longitudinal study in women with singleton low-risk pregnancies during 19–40 weeks of gestation. UA Doppler indices were serially obtained at a 4-weekly interval from a free loop of the umbilical cord using color-directed pulsed-wave Doppler ultrasonography. Sex-specific reference intervals were calculated for the fetal heart rate (HR), UA PI, resistance index (RI), and systolic/diastolic ratio (S/D) using multilevel modeling.

Results

Complete data from 294 pregnancies (a total of 1261 observations from 152 male and 142 female fetuses) were available for statistical analysis, and sex-specific reference ranges for the UA Doppler indices and fetal HR were established for the last half of pregnancy. UA Doppler indices were significantly associated with gestational age (P < 0.0001) and fetal HR (P < 0.0001). Female fetuses had 2–8% higher values for UA Doppler indices than male fetuses during gestational weeks 20⁺⁰–36⁺⁶ (P < 0.05), but not later. Female fetuses had higher HR from gestational week 26⁺⁰ until term (P < 0.05).

Conclusions

We have determined gestational age-dependent sex differences in UA Doppler indices and fetal HR during the second half of pregnancy, and correspondingly established new sex-specific reference ranges intended for refining diagnostics and monitoring individual pregnancies.

Cadmium exposure and cognitive abilities and behavior at 10 years of age: A prospective cohort study

BACKGROUND

We have previously reported inverse associations of prenatal and childhood cadmium exposure with cognition in 5-year-old Bangladeshi children.

OBJECTIVES

To assess if cadmium exposure affected cognition and behavior in the Bangladeshi children at 10 years.

METHODS

Cadmium exposure was assessed by urinary concentrations at 10 (n = 1498) and 5 years of age (n = 1453), and of the mothers in early pregnancy (n = 1299), measured by ICP-MS. Cognitive abilities were assessed with Wechsler Intelligence Scale for Children (4th edition) and behavior with the parent-rated Strengths and Difficulties Questionnaire.

RESULTS

In multivariable-adjusted models, urinary cadmium at 10 years was inversely associated with Full scale IQ and most of the sub-scales. Associations were mainly observed in boys, in whom the difference in Full scale IQ was 7.0 scores (95% CI: -11, -2.7), corresponding to 0.21 SD, when comparing those in the highest (range: 0.30-2.6 μg/L) and lowest tertile of urinary cadmium (0.036-0.18 μg/L). Urinary cadmium at 5 years was inversely, but not significantly, associated with IQ. Children in the highest exposure tertile at 10 years also had poorer Prosocial behavior scores. The association appeared strongest in girls, in whom the corresponding OR for Prosocial scores in relation to cadmium exposure at 10 years and prenatally was 0.58 (95% CI: 0.34, 0.99) and 0.48 (95% CI: 0.25, 0.93), respectively.

CONCLUSION

Childhood cadmium exposure was associated with lower intelligence in boys, and there were indications of altered behavior in girls for both prenatal and childhood exposures. Findings are of concern as similar exposure levels are common world-wide.

Prenatal exposure to glycol ethers and sex steroid hormones at birth

BACKGROUND

Glycol ethers (GEs) are oxygenated solvents widely found in occupational and consumer water-based products. Some of them are well-known reproductive and developmental toxicants.

OBJECTIVES

To study the variations in circulating sex steroid hormones, measured in cord blood, according to biomarkers of prenatal GE exposure.

METHODS

The study population comes from the PELAGIE mother-child cohort, which enrolled pregnant women from Brittany (France, 2002-2006). Maternal urine samples were collected from a random subcohort (n = 338) before 19 weeks' gestation, from which we measured 8 alkoxycarboxylic metabolites of GEs. We subsequently measured 13 sex steroid hormones and sex hormone-binding globulin (SHBG) in cord blood samples. Linear regressions adjusted for potential confounders were used, and nonlinear dose-response associations were investigated.

RESULTS

The detection rates of GE metabolites ranged from 4% to 98%; only the 5 most detected (>20%) metabolites were investigated further. Phenoxyacetic acid (detection rate > 95%) was associated with lower levels of SHBG and various steroids (17-alpha-hydroxy-Pregnenolone, delta-5-androstenediol, and dehydroepiandrosterone) among boys and higher SHBG and 16-alpha-hydroxy-dehydroepiandrosterone levels among girls. The two other highly detected metabolites, methoxyetoxyacetic acid and butoxyacetic acid, were associated with variations in estradiol. Butoxyacetic acid was associated with higher delta-5-androstenediol levels while detectable levels of methoxyacetic acid were associated with lower levels of this hormone.

CONCLUSION

Our study suggests that prenatal exposure to GE may affect endocrine response patterns, estimated by determining blood levels of sex steroid hormones in newborns. These results raise questions about the potential role of these changes in the pathways between prenatal GE exposure and previously reported adverse developmental outcomes, including impaired neurocognitive performance.

Extreme umbilical cord lengths, cord knot and entanglement: Risk factors and risk of adverse outcomes, a population-based study

Objectives

To determine risk factors for short and long umbilical cord, entanglement and knot. Explore their associated risks of adverse maternal and perinatal outcome, including risk of recurrence in a subsequent pregnancy. To provide population based gestational age and sex and parity specific reference ranges for cord length.

Design

Population based registry study.

Setting

Medical Birth Registry of Norway 1999–2013.

Population

All singleton births (gestational age>22weeks<45 weeks) (n = 856 300).

Methods

Descriptive statistics and odds ratios of risk factors for extreme cord length and adverse outcomes based on logistic regression adjusted for confounders.

Main outcome measures

Short or long cord (<10^th or >90^th percentile), cord knot and entanglement, adverse pregnancy outcomes including perinatal and intrauterine death.

Results

Increasing parity, maternal height and body mass index, and diabetes were associated with increased risk of a long cord. Large placental and birth weight, and fetal male sex were factors for a long cord, which again was associated with a doubled risk of intrauterine and perinatal death, and increased risk of adverse neonatal outcome. Anomalous cord insertion, female sex, and a small placenta were associated with a short cord, which was associated with increased risk of fetal malformations, placental complications, caesarean delivery, non-cephalic presentation, perinatal and intrauterine death. At term, cord knot was associated with a quadrupled risk of perinatal death. The combination of a cord knot and entanglement had a more than additive effect to the association to perinatal death. There was a more than doubled risk of recurrence of a long or short cord, knot and entanglement in a subsequent pregnancy of the same woman.

Conclusion

Cord length is influenced both by maternal and fetal factors, and there is increased risk of recurrence. Extreme cord length, entanglement and cord knot are associated with increased risk of adverse outcomes including perinatal death. We provide population based reference ranges for umbilical cord length.

Antibiotics, gut microbiome and obesity

Antibiotics have been hailed by many as "miracle drugs" that have been effectively treating infectious diseases for over a century, leading to a marked reduction in morbidity and mortality. However, with the increasing use of antibiotics, we are now faced not only with the increasing threat of antibiotic resistance, but also with a rising concern about potential long-term effects of antibiotics on human health, including the development of obesity. The obesity pandemic continues to increase, a problem that affects both adults and children alike. Disruptions to the gut microbiome have been linked to a multitude of adverse conditions, including obesity, type 2 diabetes, inflammatory bowel diseases, anxiety, autism, allergies, and autoimmune diseases. This review focuses on the association between antibiotics and obesity, and the role of the gut microbiome. There is strong evidence supporting the role of antibiotics in the development of obesity in well-controlled animal models. However, evidence for this link in humans is still inconclusive, and we need further well-designed clinical trials to clarify this association.

Sexual Differentiation and Sex Differences in Neural Development

Sex determination occurs at the moment of conception, as a result of XX or XY chromosome pairing. From that point, the body undergoes the process of sexual differentiation, inducing the development of physical characteristics that are easily distinguishable between the sexes and are often reflected in one's physical appearance and gender identity. Although less apparent, the brain also undergoes sexual differentiation. Sex differences in the brain are organized during a critical period of neural development and have an instrumental role in determining the physiology and behavior of an individual throughout the lifespan. Understanding the extent of sex differences in neurodevelopment also influences our understanding of the potential risk for a number of neurodevelopmental, neurological, and mental health disorders that exhibit strong sex biases. Advances made in our understanding of sexually dimorphic brain nuclei, sex differences in neural cell communication, and sex differences in the communication between the brain and peripheral organs are all research fields that have provided valuable information related to the physiological and behavioral outcomes of sex differences in brain development. More recently, investigations into the impact of epigenetic mechanisms on sexual differentiation of the brain have indicated that changes in gene expression, via epigenetic modifications, also contribute to sexual differentiation of the developing brain. Still, there are a number of important questions and ideas that have arisen from our current understanding of sex differences in neurodevelopmental processes that necessitate more time and attention in this field.

Modelling foetal exposure to maternal smoking using hepatoblasts from pluripotent stem cells

The liver is a dynamic organ which is both multifunctional and highly regenerative. A major role of the liver is to process both endo and xenobiotics. Cigarettes are an example of a legal and widely used drug which can cause major health problems for adults and constitute a particular risk to the foetus, if the mother smokes during pregnancy. Cigarette smoke contains a complex mixture of thousands of different xenobiotics, including nicotine and polycyclic aromatic hydrocarbons. These affect foetal development in a sex-specific manner, inducing sex-dependant molecular responses in different organs. To date, the effect of maternal smoking on the foetal liver has been studied in vitro using cell lines, primary tissue and animal models. While these models have proven to be useful, poor cell phenotype, tissue scarcity, batch-to-batch variation and species differences have led to difficulties in data extrapolation toward human development. Therefore, in this study we have employed hepatoblasts, derived from pluripotent stem cells, to model the effects of xenobiotics from cigarette smoke on human hepatocyte development. Highly pure hepatocyte populations (>90%) were produced in vitro and exposed to factors present in cigarette smoke. Analysis of ATP levels revealed that, independent of the sex, the majority of smoking derivatives tested individually did not deplete ATP levels below 50%. However, following exposure to a cocktail of smoking derivatives, ATP production fell below 50% in a sex-dependent manner. This was paralleled by a loss metabolic activity and secretory ability in both female and male hepatocytes. Interestingly, cell depletion was less pronounced in female hepatocytes, whereas caspase activation was ~twofold greater, indicating sex differences in cell death upon exposure to the smoking derivatives tested.

Early sex-dependent differences in response to environmental stress

Developmental plasticity enables the appearance of long-term effects in offspring caused by exposure to environmental stressors during embryonic and foetal life. These long-term effects can be traced to pre- and post-implantation development, and in both cases, the effects are usually sex specific. During preimplantation development, male and female embryos exhibit an extensive transcriptional dimorphism mainly driven by incomplete X chromosome inactivation. These early developmental stages are crucial for the establishment of epigenetic marks that will be conserved throughout development, making it a particularly susceptible period for the appearance of long-term epigenetic-based phenotypes. Later in development, gonadal formation generates hormonal differences between the sexes, and male and female placentae exhibit different responses to environmental stressors. The maternal environment, including hormones and environmental insults during pregnancy, contributes to sex-specific placental development that controls genetic and epigenetic programming during foetal development, regulating sex-specific differences, including sex-specific epigenetic responses to environmental hazards, leading to long-term effects. This review summarizes several human and animal studies examining sex-specific responses to environmental stressors during both the periconception period (caused by differences in sex chromosome dosage) and placental development (caused by both sex chromosomes and hormones). The identification of relevant sex-dependent trajectories caused by sex chromosomes and/or sex hormones is essential to define diagnostic markers and prevention/intervention protocols.

Systematic Review and Meta-Analysis of Early-Life Exposure to Bisphenol A and Obesity-Related Outcomes in Rodents

BACKGROUND

Early-life exposure to bisphenol A (BPA) has been implicated to play a role in the development of obesity.

OBJECTIVE

A systematic review with meta-analyses of experimental rodent studies was conducted to answer the following question: does early-life exposure to BPA affect the obesity-related outcomes body weight, fat (pad) weight, and circulating and tissue levels of triglycerides, free fatty acids (FFA), and leptin?

METHODS

The methodology was prespecified in a rigorous protocol using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) approach. Using PubMed and EMBASE, we identified 61 articles that met the inclusion criteria. The risk of bias and the methodological quality of these articles were assessed using the SYRCLE Risk of Bias tool, and a confidence-rating methodology was used to score the quality of evidence. Meta-analyses were performed using random effect models and standardized mean differences (SMDs), or, where possible, mean differences (MDs) were calculated.

RESULTS

Overall summary estimates indicated significant positive associations between BPA and fat weight [SMD=0.67 (95% CI: 0.53, 0.81)], triglycerides [SMD=0.97 (95% CI: 0.53, 1.40)], and FFA [SMD=0.86 (95% CI: 0.50, 1.22)], and a nonsignificant positive association with leptin levels [MD=0.37 (95% CI: -0.14, 0.87)] and a significant negative association with body weight were estimated [MD=-0.22 (95% CI: -0.37, -0.06)]. Subgroup analyses revealed stronger positive associations for most outcome measures in males and at doses below the current U.S. reference dose of 50μg/kg/d compared with doses above the reference dose. It should be noted that there was substantial heterogeneity across studies for all outcomes assessed and that there was insufficient information to assess risk of bias for most studies.

CONCLUSIONS

Findings from our systematic review suggest that early-life exposure to BPA may increase adiposity and circulating lipid levels in rodents. https://doi.org/10.1289/EHP1233.

The placenta and neurodevelopment: sex differences in prenatal vulnerability

Prenatal insults, such as maternal stress, are associated with an increased neurodevelopmental disease risk and impact males significantly more than females, including increased rates of autism, mental retardation, stuttering, dyslexia, and attention deficit/hyperactivity disorder (ADHD). Sex differences in the placenta, which begin with sex chromosomes, are likely to produce sex-specific transplacental signals to the developing brain. Our studies and others have identified X-linked genes that are expressed at higher levels in the female placenta. Through a genome-wide screen after maternal stress in mice, we identified the X-linked gene O-linked N-acetylglucosamine transferase (OGT) and demonstrated its causality in neurodevelopmental programming producing a male-specific stress phenotype. Elucidating the sex-specific molecular mechanisms involved in transplacental signals that impact brain development is key to understanding the sex bias in neurodevelopmental disorders and is expected to yield novel insight into disease risk and resilience.

The placental imprinted DLK1-DIO3 domain: a new link to prenatal and postnatal growth in humans

BACKGROUND

The developmentally important DLK1-DIO3 imprinted domain on human chromosome 14 is regulated by 2 differentially methylated regions, the intergenic differentially methylated region and the MEG3 differentially methylated region.

OBJECTIVE

The aim was to determine the natural variation in DNA methylation at these differentially methylated regions in human placentas, and to determine its link to gene expression levels at the domain. The second goal was to explore whether the domain's methylation and gene expression correlate with prenatal and early postnatal growth of the conceptus.

STUDY DESIGN

Using pyrosequencing, we determined methylation levels at CpG dinucleotides across the 2 regulatory differentially methylated regions in placentas from 91 healthy mothers. At birth, placentas and infants were weighed (gestational age 39 ± 1 weeks; birthweight SD score 0.1 ± 0.8) and placental biopsies were collected. RNA expression was quantitated by real-time polymerase chain reaction. Infants' weights and lengths were followed up monthly during the first year.

RESULTS

Methylation levels at the 2 regulatory differentially methylated regions were linked and varied considerably between placentas. MEG3 promoter differentially methylated region methylation correlated negatively with weight increase (β = -0.406, P = .001, R² = 0.206) and length increase (β = -0.363, P = .002, R² = 0.230) during the first postnatal year. The methylation level of the intergenic differentially methylated region correlated with DIO3 expression (β = 0.313, P = .032, R² = 0.152). Furthermore, the expression of both DIO3 and RTL1 (both imprinted genes within the DLK1-DIO3 domain) was negatively associated with birthweight (β = -0.331, P = .002, R² = 0.165; and β = -0.307, P = .005, R² = 0.159, respectively). RTL1 expression, in addition, was negatively linked to birth length (β = -0.306, P = .007, R² = 0.162).

CONCLUSION

Our combined findings strongly suggest that placental DNA methylation at the DLK1-DIO3 domain's intergenic differentially methylated region and MEG3 promoter differentially methylated region relates to measures of early human growth, and may thus contribute to its control.

Maternal pre-pregnancy BMI and offspring body composition in young adulthood: the modifying role of offspring sex and birth order

OBJECTIVE

To investigate if the association between maternal pre-pregnancy BMI and offspring's body composition in late adolescence and young adulthood varies by offspring birth order and sex.

DESIGN

Family cohort study, with data from registers, questionnaires and physical examinations. The main outcome under study was offspring body composition (percentage fat mass (%FM), percentage lean mass (%LM)) measured by dual-energy X-ray absorptiometry.

SETTING

Uppsala, Sweden.

SUBJECTS

Two hundred and twenty-six siblings (first-born v. second-born; average age 19 and 21 years) and their mothers.

RESULTS

In multivariable linear regression models, maternal pre-pregnancy BMI was positively associated with daughter's %FM, with stronger estimates for first-born (β=0·97, 95 % CI 0·14, 1·80) v. second-born daughters (β=0·64, 95 % CI 0·08, 1·20). Mother's BMI before her first pregnancy was associated with her second-born daughter's body composition (β=1·05, 95 % CI 0·31, 1·79 (%FM)) Similar results albeit in the opposite direction were observed for %LM. No significant associations were found between pre-pregnancy BMI and %FM (β=0·59, 95 % CI-0·27, 1·44 first-born; β=-0·13, 95 % CI-0·77, 0·52 second-born) or %LM (β=-0·54, 95 % CI-1·37, 0·28 first-born; β=0·11, 95 % CI-0·52, 0·74 second-born) for sons.

CONCLUSIONS

A higher pre-pregnancy BMI was associated with higher offspring %FM and lower offspring %LM in late adolescence and young adulthood, with stronger associations for first-born daughters. Preventing obesity at the start of women's reproductive life might reduce the risk of obesity in her offspring, particularly for daughters.

Pregnant women carrying female fetuses are at higher risk of placental malaria infection

BACKGROUND

The pathophysiology of the placental malaria is not fully understood. If there is a fetal sex-specific susceptibility to malaria infection, this might add to the previous knowledge on the immunology, endocrinology and pathophysiology of placental malaria infections.

AIMS

This study was conducted to assess whether the sex of the fetus was associated with placental malaria infections.

SUBJECTS AND METHODS

A cross-sectional study was performed including a secondary analysis of a cohort of women who were investigated for prevalence and risk factors (including fetal sex) for placental malaria in eastern Sudan. Placental histology was used to diagnose placental malaria infections.

RESULTS

Among 339 women enrolled, the mean (SD) age was 25.8 (6.7) years and parity was 2.7 (2.2). Among the new born babies, 157 (46.3%) were male and 182 (53.7%) were female. Five (1.5%), 9 (2.7%) and 103 (30.4%) of the 339 placentas had active, active-chronic, past-chronic malaria infection on histopathology examination respectively, while 222 (65.5%) of them showed no malaria infection. Logistic regression analyses showed no associations between maternal age or parity and placental malaria infections. Women who have blood group O (OR = 1.95, 95% CI = 1.19-3.10; P = 0.007) and women who had female new born were at higher risk for placental malaria infections (OR = 2.55, 95% CI = 1.57-4.13; P< 0.001).

CONCLUSION

Fetal gender may be a novel risk factor for placental malaria. In this work the female placentas were at higher risk for malaria infections than the male placentas.

Antenatal antipsychotic exposure induces multigenerational and gender-specific programming of adiposity and glucose tolerance in adult mouse offspring

Second-generation antipsychotics (SGAs) are well known for their metabolic side effects in humans, including obesity and diabetes. These compounds are maintained during pregnancy to prevent the relapse of psychoses, but they readily diffuse across the placenta to the fetus, as documented with the widely-prescribed drug olanzapine (OLZ). However, observational studies have provided conflicting results on the potential impact of SGAs on fetal growth and body weight, and their effects on metabolic regulation in the offspring. For this reason, our study has tested whether antenatal exposure of CD1 mice to OLZ influenced metabolic outcomes in the offspring of the first (F1) and second (F2) generations. In F1 mice, OLZ antenatal treatment caused a decrease in neonatal body weight in both genders, an effect that persisted throughout life only in male animals. Interestingly, F1 female mice also displayed altered glucose homoeostasis. F2 mice, generated by mating normal males with F1 female mice exposed to OLZ during antenatal life, exhibited higher neonatal body weights which persisted only in F2 female animals. This was associated with expansion of fat mass and a concordant pattern of adipose tissue gene expression. Moreover, male and female F2 mice were glucose-intolerant. Thus, our study has demonstrated that antenatal OLZ exposure induces multigenerational and gender-specific programming of glucose tolerance in the offspring mice as adults, and points to the need for careful monitoring of children exposed to SGAs during pregnancy.

Sex-Specific Neurodevelopmental Programming by Placental Insulin Receptors on Stress Reactivity and Sensorimotor Gating

BACKGROUND

Diabetes, obesity, and overweight are prevalent pregnancy complications that predispose offspring to neurodevelopmental disorders, including autism, attention-deficit/hyperactivity disorder, and schizophrenia. Although male individuals are three to four times more likely than female individuals to develop these disorders, the mechanisms driving the sex specificity of disease vulnerability remain unclear. Because defective placental insulin receptor (InsR) signaling is a hallmark of pregnancy metabolic dysfunction, we hypothesized that it may be an important contributor and novel mechanistic link to sex-specific neurodevelopmental changes underlying disease risk.

METHODS

We used Cre/loxP transgenic mice to conditionally target InsRs in fetally derived placental trophoblasts. Adult offspring were evaluated for effects of placental trophoblast-specific InsR deficiency on stress sensitivity, cognitive function, sensorimotor gating, and prefrontal cortical transcriptional reprogramming. To evaluate molecular mechanisms driving sex-specific outcomes, we assessed genome-wide expression profiles in the placenta and fetal brain.

RESULTS

Male, but not female, mice with placental trophoblast-specific InsR deficiency showed a significantly increased hypothalamic-pituitary-adrenal axis stress response and impaired sensorimotor gating, phenotypic effects that were associated with dysregulated nucleotide metabolic processes in the male prefrontal cortex. Within the placenta, InsR deficiency elicited changes in gene expression, predominantly in male mice, reflecting potential shifts in vasculature, amino acid transport, serotonin homeostasis, and mitochondrial function. These placental disruptions were associated with altered gene expression profiles in the male fetal brain and suggested delayed cortical development.

CONCLUSIONS

Together, these data demonstrate the novel role of placental InsRs in sex-specific neurodevelopment and reveal a potential mechanism for neurodevelopmental disorder risk in pregnancies complicated by maternal metabolic disorders, including diabetes and obesity.

Offspring sex and parental health and mortality

Increased mortality has been observed in mothers and fathers with male offspring but little is known regarding specific diseases. In a register linkage we linked women born 1925–1954 having survived to age 50 (n = 661,031) to offspring and fathers (n = 691,124). Three approaches were used: 1) number of total boy and girl offspring, 2) sex of the first and second offspring and 3) proportion of boys to total number of offspring. A sub-cohort (n = 50,736 mothers, n = 44,794 fathers) from survey data was analysed for risk factors. Mothers had increased risk of total and cardiovascular mortality that was consistent across approaches: cardiovascular mortality of 1.07 (95% CI: 1.03–1.11) per boy (approach 2), 1.04 (1.01–1.07) if the first offspring was a boy, and 1.06 (1.01–1.10) if the first two offspring were boys (approach 3). We found that sex of offspring was not associated with total or cardiovascular mortality in fathers. For other diseases or risk factors no robust associations were seen in mothers or fathers. Increased cardiovascular risk in mothers having male offspring suggests a maternal disease specific mechanism. The lack of consistent associations on measured risk factors could suggest other biological pathways than those studied play a role in generating this additional cardiovascular risk.

Sexual Dimorphic Responses in Lymphocytes of Healthy Individuals after Carica papaya Consumption

Sexual dimorphism in immune response is widely recognized, but few human studies have observed this distinction. Food with endo-immunomodulatory potential may reveal novel sex-biased in vivo interactions. Immunomodulatory effects of Carica papaya were compared between healthy male and female individuals. Volunteers were given fixed meals supplemented with papaya for 2 days. Changes in blood immune profiles and hormone levels were determined. In females, total natural killer (NK) cell percentages decreased (12.7 ± 4.4 vs 14.6 ± 5.8%, p = 0.018, n = 18) while B cells increased (15.2 ± 5.5 vs 14.5 ± 5.0, p = 0.037, n = 18) after papaya consumption. Increased 17β-estradiol (511.1 ± 579.7 vs 282.7 ± 165.0 pmol/l, p = 0.036, n = 9) observed in females may be crucial to this change. Differentiation markers (CD45RA, CD69, CD25) analyzed on lymphocytes showed naïve (CD45RA⁺) non-CD4⁺ lymphocytes were reduced in females (40.7 ± 8.1 vs 46.8 ± 5.4%, p = 0.012, n = 8) but not males. A general suppressive effect of papaya on CD69⁺ cells, and higher percentage of CD69⁺ populations in females and non-CD4 lymphocytes, may be relevant. CD107a⁺ NK cells were significantly increased in males (16.8 ± 7.0 vs 14.7 ± 4.8, p = 0.038, n = 9) but not females. Effect in females may be disrupted by the action of progesterone, which was significantly correlated with this population (R = 0.771, p = 0.025, n = 8) after papaya consumption. In males, total T helper cells were increased (33.4 ± 6.4 vs 32.4 ± 6.1%, p = 0.040, n = 15). Strong significant negative correlation between testosterone and CD25⁺CD4⁺ lymphocytes, may play a role in the lower total CD4⁺ T cells reported in males. Thus, dissimilar immune profiles were elicited in the sexes after papaya consumption and may have sex hormone influence.

The aquaglyceroporin AQP9 contributes to the sex-specific effects of in utero arsenic exposure on placental gene expression

BACKGROUND

Sex-specific factors play a major role in human health and disease, including responses to environmental stresses such as toxicant exposure. Increasing evidence suggests that such sex differences also exist during fetal development. In a previous report using the resources of the New Hampshire Birth Cohort Study (NHBCS), we found that low-to-moderate in utero exposure to arsenic, a highly toxic and widespread pollutant, was associated with altered expression of several key developmental genes in the fetal portion of the placenta. These associations were sex-dependent, suggesting that in utero arsenic exposure differentially impacts male and female fetuses. In the present study, we investigated the molecular basis for these sex-specific responses to arsenic.

METHODS

Using NanoString technology, we further analyzed the fetal placenta samples from the NHBCS for the expression of genes encoding arsenic transporters and metabolic enzymes. Multivariable linear regression analysis was used to examine their relationship with arsenic exposure and with key developmental genes, after stratification by fetal sex.

RESULTS

We found that maternal arsenic exposure was strongly associated with expression of the AQP9 gene, encoding an aquaglyceroporin transporter, in female but not male fetal placenta. Moreover, AQP9 expression associated with that of a subset of female-specific arsenic-responsive genes.

CONCLUSIONS

Our results suggest that AQP9 is upregulated in response to arsenic exposure in female, but not male, fetal placenta. Based on these results and prior studies, increased AQP9 expression may lead to increased arsenic transport in the female fetal placenta, which in turn may alter the expression patterns of key developmental genes that we have previously shown to be associated with arsenic exposure. Thus, this study suggests that AQP9 may play a role in the sex-specific effects of in utero arsenic exposure.

Placental Origins of Chronic Disease

Epidemiological evidence links an individual's susceptibility to chronic disease in adult life to events during their intrauterine phase of development. Biologically this should not be unexpected, for organ systems are at their most plastic when progenitor cells are proliferating and differentiating. Influences operating at this time can permanently affect their structure and functional capacity, and the activity of enzyme systems and endocrine axes. It is now appreciated that such effects lay the foundations for a diverse array of diseases that become manifest many years later, often in response to secondary environmental stressors. Fetal development is underpinned by the placenta, the organ that forms the interface between the fetus and its mother. All nutrients and oxygen reaching the fetus must pass through this organ. The placenta also has major endocrine functions, orchestrating maternal adaptations to pregnancy and mobilizing resources for fetal use. In addition, it acts as a selective barrier, creating a protective milieu by minimizing exposure of the fetus to maternal hormones, such as glucocorticoids, xenobiotics, pathogens, and parasites. The placenta shows a remarkable capacity to adapt to adverse environmental cues and lessen their impact on the fetus. However, if placental function is impaired, or its capacity to adapt is exceeded, then fetal development may be compromised. Here, we explore the complex relationships between the placental phenotype and developmental programming of chronic disease in the offspring. Ensuring optimal placentation offers a new approach to the prevention of disorders such as cardiovascular disease, diabetes, and obesity, which are reaching epidemic proportions.

Single-step PCR-based genetic sex determination of rat tissues and cells

The advent of genome editing strategies has expanded the range of animal models available for gene manipulation and renewed research interest in the rat. Gender is a key variable for in vivo gene function analyses. Here, we present a simple PCR-based method to determine genetic sex in the rat.

Sex-specific associations of maternal birthweight with offspring birthweight in the Omega study

PURPOSE

We investigated nonlinear and offspring sex-specific associations of maternal birthweight (BW) with offspring BW among participants of the Omega study, a pregnancy cohort.

METHODS

Maternal BW was modeled as a continuous variable, linear spline and binary variable indicating low birthweight (LBW; <2500 vs. ≥2500 grams). Offspring BW was modeled as a continuous and binary variable in regression models. Nonlinearity was assessed using likelihood ratio tests (LRTs) in marginal linear spline models.

RESULTS

For every 100-gram increase of maternal BW, offspring BW increased by 22.29 (95% CI: 17.57, 27.02) or 23.41 (95% CI: 6.87, 39.96) grams among mothers with normal BW or born macrosomic, respectively, but not among LBW mothers (β = -8.61 grams; 95% CI: -22.88, 5.65; LRT P-value = .0005). For every 100-gram increase in maternal BW, BW of male offspring increased 23.47 (95% CI: 16.75, 30.19) or 25.21 (95% CI: 4.35, 46.07) grams among mothers with normal BW or born macrosomic, respectively, whereas it decreased 31.39 grams (95% CI: -51.63, -11.15) among LBW mothers (LRT P-value < .0001). Corresponding increases in BW of female offspring (16-22 grams) did not differ among mothers with LBW, normal BW or macrosomia (LRT P-value = .9163).

CONCLUSIONS

Maternal and offspring BW associations are evident among normal BW and macrosomic mothers. These associations differ by offspring sex.

Parental Exposure to Dim Light at Night Prior to Mating Alters Offspring Adaptive Immunity

Exposure to dim light at night (dLAN) disrupts natural light/dark cycles and impairs endogenous circadian rhythms necessary to maintain optimal biological function, including the endocrine and immune systems. We have previously demonstrated that white dLAN compromises innate and cell mediated immune responses in adult Siberian hamsters (Phodopus sungorus). We hypothesized that dLAN has transgenerational influences on immune function. Adult male and female Siberian hamsters were exposed to either dark nights (DARK) or dLAN (~5 lux) for 9 weeks, then paired in full factorial design, mated, and thereafter housed under dark nights. Offspring were gestated and reared in dark nights, then tested as adults for cell-mediated and humoral immunity. Maternal exposure to dLAN dampened delayed type hypersensitivity (DTH) responses in male offspring. Maternal and paternal exposure to dLAN reduced DTH responses in female offspring. IgG antibodies to a novel antigen were elevated in offspring of dams exposed to dLAN. Paternal exposure to dLAN decreased splenic endocrine receptor expression and global methylation in a parental sex-specific manner. Together, these data suggest that exposure to dLAN has transgenerational effects on endocrine-immune function that may be mediated by global alterations in the epigenetic landscape of immune tissues.

Prenatal Exposure to Perfluoroalkyl Substances and Adiposity in Early and Mid-Childhood

BACKGROUND

Few studies have examined whether prenatal exposure to perfluoroalkyl substances (PFASs) is associated with childhood adiposity.

OBJECTIVE

We examined associations of prenatal exposure to PFASs with adiposity in early and mid-childhood.

METHODS

We measured plasma PFAS concentrations in 1,645 pregnant women (median, 9.6 weeks gestation) enrolled in Project Viva, a prospective pre-birth cohort study in Massachusetts (USA), between 1999 and 2002. We assessed overall and central adiposity in 1,006 children in early childhood (median, 3.2 years) and 876 in mid-childhood (median, 7.7 years) using anthropometric and dual X-ray absorptiometry (DXA) measurements. We fitted multivariable linear regression models to estimate exposure-outcome associations and evaluated effect modification by child sex.

RESULTS

Median (25-75th percentiles) prenatal plasma perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA) concentrations in children assessed in early childhood were 5.6 (4.1-7.7), 24.8 (18.4-33.9), 2.4 (1.6-3.8), and 0.6 (0.5-0.9) ng/mL, respectively. Among girls, each interquartile range increment of prenatal PFOA concentrations was associated with 0.21 kg/m2 (95% CI: -0.05, 0.48) higher body mass index, 0.76 mm (95% CI: -0.17, 1.70) higher sum of subscapular and triceps skinfold thickness, and 0.17 kg/m2 (95% CI: -0.02, 0.36) higher DXA total fat mass index in mid-childhood. Similar associations were observed for PFOS, PFHxS, and PFNA. We observed null associations for boys and early-childhood adiposity measures.

CONCLUSIONS

In this cohort, prenatal exposure to PFASs was associated with small increases in adiposity measurements in mid-childhood, but only among girls. Citation: Mora AM, Oken E, Rifas-Shiman SL, Webster TF, Gillman MW, Calafat AM, Ye X, Sagiv SK. 2017. Prenatal exposure to perfluoroalkyl substances and adiposity in early and mid-childhood. Environ Health Perspect 125:467-473; http://dx.doi.org/10.1289/EHP246.

Sexual epigenetic dimorphism in the human placenta: implications for susceptibility during the prenatal period

AIM

Sex-based differences in response to adverse prenatal environments and infant outcomes have been observed, yet the underlying mechanisms for this are unclear. The placental epigenome may be a driver of these differences.

METHODS

Placental DNA methylation was assessed at more than 480,000 CpG sites from male and female infants enrolled in the extremely low gestational age newborns cohort (ELGAN) and validated in a separate US-based cohort. The impact of gestational age on placental DNA methylation was further examined using the New Hampshire Birth Cohort Study for a total of n = 467 placentas.

RESULTS

A total of n = 2745 CpG sites, representing n = 587 genes, were identified as differentially methylated (p < 1 × 10-7). The majority (n = 582 or 99%) of these were conserved among the New Hampshire Birth Cohort. The identified genes encode proteins related to immune function, growth/transcription factor signaling and transport across cell membranes.

CONCLUSION

These data highlight sex-dependent epigenetic patterning in the placenta and provide insight into differences in infant outcomes and responses to the perinatal environment.

Lamarck rises from his grave: parental environment-induced epigenetic inheritance in model organisms and humans

Organisms can change their physiological/behavioural traits to adapt and survive in changed environments. However, whether these acquired traits can be inherited across generations through non-genetic alterations has been a topic of debate for over a century. Emerging evidence indicates that both ancestral and parental experiences, including nutrition, environmental toxins, nurturing behaviour, and social stress, can have powerful effects on the physiological, metabolic and cellular functions in an organism. In certain circumstances, these effects can be transmitted across several generations through epigenetic (i.e. non-DNA sequence-based rather than mutational) modifications. In this review, we summarize recent evidence on epigenetic inheritance from parental environment-induced developmental and physiological alterations in nematodes, fruit flies, zebrafish, rodents, and humans. The epigenetic modifications demonstrated to be both susceptible to modulation by environmental cues and heritable, including DNA methylation, histone modification, and small non-coding RNAs, are also summarized. We particularly focus on evidence that parental environment-induced epigenetic alterations are transmitted through both the maternal and paternal germlines and exert sex-specific effects. The thought-provoking data presented here raise fundamental questions about the mechanisms responsible for these phenomena. In particular, the means that define the specificity of the response to parental experience in the gamete epigenome and that direct the establishment of the specific epigenetic change in the developing embryos, as well as in specific tissues in the descendants, remain obscure and require elucidation. More precise epigenetic assessment at both the genome-wide level and single-cell resolution as well as strategies for breeding at relatively sensitive periods of development and manipulation aimed at specific epigenetic modification are imperative for identifying parental environment-induced epigenetic marks across generations. Considering their diverse epigenetic architectures, the conservation and prevalence of the mechanisms underlying epigenetic inheritance in non-mammals require further investigation in mammals. Interpretation of the consequences arising from epigenetic inheritance on organisms and a better understanding of the underlying mechanisms will provide insight into how gene-environment interactions shape developmental processes and physiological functions, which in turn may have wide-ranging implications for human health, and understanding biological adaptation and evolution.

Association Between Preterm Birth and Lower Adult Height in Women

We examined whether being born preterm was associated with changes in adult anthropometry in women. We assessed data on 201,382 women (born in 1973-1988) from the Swedish Birth Register. The mean age was 26.0 years. Of the women in our cohort, 663 were born very preterm (<32 weeks of gestation), 8,247 were born moderately preterm (at least 32 weeks but <37 weeks), and 192,472 were born at term (37-41 weeks). Subgroup analyses were carried out among siblings and also after adjustment for maternal anthropometric data. Statistical tests were 2-sided. Decreasing gestational age was associated with lower height (-1.1 mm per week of gestation; P < 0.0001), so that women who were born very preterm were on average 12 mm shorter than women who were born moderately preterm (P < 0.0001) and 17 mm shorter than women born at term (P < 0.0001). Compared with women who were born at term, those who were born very preterm had 2.9 times higher odds of short stature (<155.4 cm), and those born moderately preterm had 1.43 times higher odds. Subgroup analyses showed no differences between women born moderately preterm and those born at term but accentuated differences from women born very preterm. Among siblings (n = 2,388), very preterm women were 23 mm shorter than those born at term (P = 0.003), with a 20-mm difference observed in subgroup analyses (n = 27,395) that were adjusted for maternal stature (P < 0.001). A shorter final height was associated with decreasing gestational age, and this association was particularly marked in women born very preterm.

The sex of the foetus affects maternal blood glucose concentrations in overweight and obese pregnant women

There is increasing evidence that the sex of the foetus may alter the maternal metabolic milieu during pregnancy. Following a randomized controlled trial of exercise in overweight and obese pregnant women, we assessed whether the sex of the foetus was associated with changes in maternal metabolism. Data were analysed on 74 randomized participants who completed the trial, including 38 mothers carrying males and 36 mothers carrying females. At 19 weeks of gestation, mothers carrying boys had higher blood glucose concentrations than those carrying girls (5.4 vs 4.9 mmol/l; p = .046). At 36 weeks of gestation, differences were more marked, with blood glucose concentrations 15% higher in mothers carrying females (5.7 vs 5.0 mmol/l; p = .004). In addition, mothers carrying girls had higher concentrations of hs-CRP across pregnancy (5.0 vs 3.6 mg/l; p = .029). Our findings provide further evidence that the sex of the foetus appears to influence maternal metabolism.

Review: Sexual dimorphism in the formation, function and adaptation of the placenta

Exposure of the embryo or fetus to perturbations in utero can result in intrauterine growth restriction, a primary risk factor for the development of adult disease. However, despite similar exposures, males and females often have altered disease susceptibility or progression from different stages of life. Fetal growth is largely mediated by the placenta, which, like the fetus is genetically XX or XY. The placenta and its associated trophoblast lineages originate from the trophectoderm (TE) of the early embryo. Rodent models (rat, mouse, spiny mouse), have been used extensively to examine placenta development and these have demonstrated the growth trajectory of the placenta in females is generally slower compared to males, and also shows altered adaptive responses to stressful environments. These placental adaptations are likely to depend on the type of stressor, duration, severity and the window of exposure during development. Here we describe the divergent developmental pathways between the male and female placenta contributing to altered differentiation of the TE derived trophoblast subtypes, placental growth, and formation of the placental architecture. Our focus is primarily genetic or environmental perturbations in rodent models which show altered placental responsiveness between sexes. We suggest that perturbations during early placental development may have greater impact on viability and growth of the female fetus whilst those occurring later in gestation may preferentially affect the male fetus. This may be of great relevance to human pregnancies which result from assisted reproductive technologies or complications such as pre-eclampsia and diabetes.

Maternal high fat diet deficient in vitamin B12 influences long chain polyunsaturated fatty acid composition in rats

OBJECTIVE

In India, there is a rise in non-communicable diseases due to diets deficient in vitamin B₁₂, low in docosahexaenoic acid (DHA) and increased consumption of westernized diet. The present study aims to examine the effect of maternal high fat diet (HFD) in absence of vitamin B₁₂ on pregnancy outcome and tissue fatty acid composition in dams.

METHODS

Pregnant Wistar rats were assigned to following diets: Control (C), HFD, High fat diet supplemented with omega-3 fatty acids (HFDO), 4) High fat diet deficient in vitamin B₁₂ (HFBD), High fat deficient in vitamin B₁₂ supplemented with omega-3 fatty acids (HFBDO).

RESULTS

There was no effect on pregnancy outcome as a consequence of different dietary treatments. The levels of DHA in HFBD group were lower (p < 0.05 for both) in placenta as compared to both control and HFD groups, which were improved by omega-3 fatty acid supplementation.

CONCLUSION

This data suggests that maternal HFD (using dairy fat) did not adversely affect pregnancy outcome. However, maternal HFBD reduced levels of placental DHA. This may have implications for reduced fetal brain growth and development.

Exploring sexual dimorphism in placental circulation at 22-24 weeks of gestation: A cross-sectional observational study

INTRODUCTION

Placental blood flow is closely associated with fetal growth and wellbeing. Recent studies suggest that there are differences in blood flow between male and female fetuses. We hypothesized that sexual dimorphism exists in fetal and placental blood flow at 22-24 weeks of gestation.

METHODS

This was a prospective cross-sectional study of 520 healthy pregnant women. Blood flow velocities of the middle cerebral artery (MCA), umbilical artery (UA), umbilical vein (UV) and the uterine arteries (UtA) were measured using Doppler ultrasonography. UV and UtA diameters were measured using two-dimensional ultrasonography and power Doppler angiography. Volume blood flows (Q) of the UV and UtA were calculated. Maternal haemodynamics was assessed with impedance cardiography. UtA resistance (R_uta) was computed as MAP/Q_uta.

RESULTS

UA PI was significantly (p = 0.008) higher in female fetuses (1.19 ± 0.15) compared with male fetuses (1.15 ± 0.14). MCA PI, cerebro-placental ratio (MCA PI/UA PI), Q_uv, UtA PI, Q_uta and R_uta were not significantly different between groups. At delivery, the mean birth weight and placental weight of female infants (3504 g and 610 g) were significantly (p = 0.0005 and p = 0.039) lower than that of the male infants (3642 g and 634 g).

DISCUSSION

We have demonstrated sexual dimorphism in UA PI, a surrogate for placental vascular resistance, at 22-24 weeks of gestation. Therefore, it would be useful to know when this difference emerges and whether it translates into blood flow differences that may impact upon the fetal growth trajectory.

Morphologic and molecular changes in the placenta: what we can learn from environmental exposures

In mammals, the extraembryonic tissues, which include the placenta, are crucial for embryonic development and growth. Because the placenta is no longer needed for postnatal life, however, it has been relatively understudied as a tissue of interest in biomedical research. Recently, increased efforts have been placed on understanding the placenta and how it may play a key role in human health and disease. In this review, we discuss two very different types of environmental exposures: assisted reproductive technologies and in utero exposure to endocrine-disrupting chemicals. We summarize the current literature on their effects on placental development in both rodent and human, and comment on the potential use of placental biomarkers as predictors of offspring health outcomes.

Responses of bovine early embryos to S-adenosyl methionine supplementation in culture

AIM

There is a growing concern about the potential adverse effects of high dose folic acid (FA) supplementation before and during pregnancy. FA metabolism generates S-adenosyl methionine (SAM) which is an important cofactor of epigenetic programming. We sought to assess the impact of a large dose of SAM on early embryo development.

MATERIALS & METHODS

In vitro cultured bovine embryos were treated with SAM from the eight-cell stage to the blastocyst stage. In addition to the phenotype, the genome-wide epigenetic and transcription profiles were analyzed.

RESULTS

Treatment significantly improved embryo hatching and caused a shift in sex ratio in favor of males. SAM caused genome-wide hypermethylation mainly in exonic regions and in CpG islands. Although differentially expressed genes were associated with response to nutrients and developmental processes, no correspondence was found with the differentially methylated regions, suggesting that cellular responses to SAM treatment during early embryo development may not require DNA methylation-driven changes.

CONCLUSION

Since bovine embryos were not indifferent to SAM, effects of large-dose FA supplements on early embryonic development in humans cannot be ruled out.