Epigenetic influences that modulate infant growth, development, and disease

Using Residual Newborn Blood Spots to Investigate CpG Methylation in Relation to Air Pollution and Congenital Heart Defects

BACKGROUND

The prevalence of tetralogy of Fallot (TOF), a common congenital heart defect, has increased over the last two decades.

METHODS

Genome-wide CpG methylation patterns were assessed and analyzed in relation to gestational air pollution exposure among 24 infants with TOF and 24 sex-matched control infants without a birth defect from a North Carolina population-based, case-control study of major structural birth defects (2006-2011). Air pollution exposure during obstetric weeks 3-8 was assigned based on self-reported residence. DNA was extracted from residual newborn blood spots, and DNA methylation levels were measured using the Illumina EPIC Array.

RESULTS

Cases had higher exposure to both PM2 .5 and O3 compared to controls. No specific CpG loci were statistically significantly associated with TOF status or air pollution exposure; however, we observed associations between TOF case status and DNA methylation at specific genomic regions with genes enriched for functions in metabolism. Additionally, there were significant regions that displayed differential DNA methylation in relation to air pollution exposure within genes involved in apoptosis, necrosis, inflammation, and immune response pathways.

CONCLUSIONS

Generally, air pollution exposure and TOF were associated with differential DNA methylation in distinct genes. These results highlight suggestive links between the environment, epigenome, and TOF to be further investigated in larger studies.

Dexamethasone as an emerging environmental pollutant: Disruption of cholesterol-dependent synaptogenesis in the hippocampus and subsequent neurobehavioral impacts in offspring

When fetuses are exposed to abnormally high levels of glucocorticoids in utero, irreversible damage to neuronal synaptogenesis occurs, leading to long-term cognitive and emotional behavioral abnormalities after birth. In this study, we investigated how maternal exposure to a novel environmental pollutant-synthetic glucocorticoid dexamethasone-affects offspring cognitive and emotional behaviors enduringly. We noted that offspring subjected to maternal dexamethasone exposure (MDE) displayed cognitive and emotional neurobehavioral deficits beginning in infancy, and these impairments persisted into adulthood. The principal mechanism involves MDE-induced damage to hippocampal neuronal synapse formation in the offspring, primarily due to a cholesterol deficiency which destabilizes neuronal membranes, thereby affecting normal synapse formation and ultimately leading to cognitive and emotional deficiencies. Specifically, we demonstrated abnormal activation of glucocorticoid receptors in hippocampal astroglial cells of MDE offspring, which triggers changes in the miR-450a-3p/HAT1/ABCG1 signaling axis, causing impaired cholesterol efflux in astroglial cells and insufficient cholesterol supply to neurons, further impairing synaptogenesis. This research not only underscores the significant impact of prenatal environmental pollutants on long-term health outcomes in offspring but also broadens our understanding of how prenatal exposure to glucocorticoids affects brain development in the progeny, providing new insights for interventions in neurodevelopmental and psychiatric disorders of fetal origin.

Time-dependent gene-environment interactions are essential drivers of asthma initiation and persistence

Asthma is a clinical syndrome caused by heterogeneous underlying mechanisms with some of them having a strong genetic component. It is known that up to 82% of atopic asthma has a genetic background with the rest being influenced by environmental factors that cause epigenetic modification(s) of gene expression. The interaction between the gene(s) and the environment has long been regarded as the most likely explanation of asthma initiation and persistence. Lately, much attention has been given to the time frame the interaction occurs since the host response (immune or biological) to environmental triggers, differs at different developmental ages. The integration of the time variant into asthma pathogenesis is appearing to be equally important as the gene(s)-environment interaction. It seems that, all three factors should be present to trigger the asthma initiation and persistence cascade. Herein, we introduce the importance of the time variant in asthma pathogenesis and emphasize the long-term clinical significance of the time-dependent gene-environment interactions in childhood.

Genome-wide DNA methylation analysis related to ALS patient progression and survival

BACKGROUND

Epigenetics contributes to the pathogenesis of amyotrophic lateral sclerosis (ALS). We aimed to characterize the DNA methylation profiles associated with clinical heterogeneity in disease progression and survival among patients.

METHODS

We included a cohort of 41 patients with sporadic ALS, with a median follow-up of 86.9 months, and 27 rigorously matched healthy controls. Blood-based genome-wide DNA methylation analysis was conducted.

RESULTS

A total of 948 progression rate-associated differentially methylated positions, 298 progression rate-associated differentially methylated regions (R-DMRs), 590 survival time-associated DMPs, and 197 survival time-associated DMRs (S-DMRs) were identified, using complementary grouping strategies. Enrichment analysis of differentially methylated genes highlighted the involvement of synapses and axons in ALS progression and survival. Clinical analysis revealed a positive correlation between the average methylation levels of the R-DMR in PRDM8 and disease progression rate (r = 0.479, p = 0.002). Conversely, there was an inverse correlation between the average methylation levels of the R-DMR in ANKRD33 and disease progression rate (r = - 0.476, p = 0.002). In addition, patients with higher methylation levels within the S-DMR of ZNF696 experienced longer survival (p = 0.016), while those with elevated methylation levels in the S-DMR of RAI1 had shorter survival (p = 0.006).

CONCLUSION

DNA methylation holds promise as a potential biomarker for tracking disease progression and predicting survival outcome and also offers targets for precision medicine.

Identification of MARK2, CCDC71, GATA2, and KLRC3 as candidate diagnostic genes and potential therapeutic targets for repeated implantation failure with antiphospholipid syndrome by integrated bioinformatics analysis and machine learning

Background

Antiphospholipid syndrome (APS) is a group of clinical syndromes of thrombosis or adverse pregnancy outcomes caused by antiphospholipid antibodies, which increase the incidence of in vitro fertilization failure in patients with infertility. However, the common mechanism of repeated implantation failure (RIF) with APS is unclear. This study aimed to search for potential diagnostic genes and potential therapeutic targets for RIF with APS.

Methods

To obtain differentially expressed genes (DEGs), we downloaded the APS and RIF datasets separately from the public Gene Expression Omnibus database and performed differential expression analysis. We then identified the common DEGs of APS and RIF. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed, and we then generated protein-protein interaction. Furthermore, immune infiltration was investigated by using the CIBERSORT algorithm on the APS and RIF datasets. LASSO regression analysis was used to screen for candidate diagnostic genes. To evaluate the diagnostic value, we developed a nomogram and validated it with receiver operating characteristic curves, then analyzed these genes in the Comparative Toxicogenomics Database. Finally, the Drug Gene Interaction Database was searched for potential therapeutic drugs, and the interactions between drugs, genes, and immune cells were depicted with a Sankey diagram.

Results

There were 11 common DEGs identified: four downregulated and seven upregulated. The common DEG analysis suggested that an imbalance of immune system-related cells and molecules may be a common feature in the pathophysiology of APS and RIF. Following validation, MARK2, CCDC71, GATA2, and KLRC3 were identified as candidate diagnostic genes. Finally, Acetaminophen and Fasudil were predicted as two candidate drugs.

Conclusion

Four immune-associated candidate diagnostic genes (MARK2, CCDC71, GATA2, and KLRC3) were identified, and a nomogram for RIF with APS diagnosis was developed. Our findings may aid in the investigation of potential biological mechanisms linking APS and RIF, as well as potential targets for diagnosis and treatment.

Gestational dexamethasone exposure impacts hippocampal excitatory synaptic transmission and learning and memory function with transgenerational effects

The formation of learning and memory is regulated by synaptic plasticity in hippocampal neurons. Here we explored how gestational exposure to dexamethasone, a synthetic glucocorticoid commonly used in clinical practice, has lasting effects on offspring's learning and memory. Adult offspring rats of prenatal dexamethasone exposure (PDE) displayed significant impairments in novelty recognition and spatial learning memory, with some phenotypes maintained transgenerationally. PDE impaired synaptic transmission of hippocampal excitatory neurons in offspring of F1 to F3 generations, and abnormalities of neurotransmitters and receptors would impair synaptic plasticity and lead to impaired learning and memory, but these changes failed to carry over to offspring of F5 and F7 generations. Mechanistically, altered hippocampal miR-133a-3p-SIRT1-CDK5-NR2B signaling axis in PDE multigeneration caused inhibition of excitatory synaptic transmission, which might be related to oocyte-specific high expression and transmission of miR-133a-3p. Together, PDE affects hippocampal excitatory synaptic transmission, with lasting consequences across generations, and CDK5 in offspring's peripheral blood might be used as an early-warning marker for fetal-originated learning and memory impairment.

Role of microRNA in Endocrine Disruptor-Induced Immunomodulation of Metabolic Health

The prevalence of poor metabolic health is growing exponentially worldwide. This condition is associated with complex comorbidities that lead to a compromised quality of life. One of the contributing factors recently gaining attention is exposure to environmental chemicals, such as endocrine-disrupting chemicals (EDCs). Considerable evidence suggests that EDCs can alter the endocrine system through immunomodulation. More concerning, EDC exposure during the fetal development stage has prominent adverse effects later in life, which may pass on to subsequent generations. Although the mechanism of action for this phenomenon is mostly unexplored, recent reports implicate that non-coding RNAs, such as microRNAs (miRs), may play a vital role in this scenario. MiRs are significant contributors in post-transcriptional regulation of gene expression. Studies demonstrating the immunomodulation of EDCs via miRs in metabolic health or towards the Developmental Origins of Health and Disease (DOHaD) Hypothesis are still deficient. The aim of the current review was to focus on studies that demonstrate the impact of EDCs primarily on innate immunity and the potential role of miRs in metabolic health.

Abnormal transcriptome-wide DNA demethylation induced by folate deficiency causes neural tube defects

Neural tube defect (NTDs) is one of the most common and serious fetal and neonatal birth defects. Neural tube closure (NTC) is an exquisitely coordinated process and this procedure is influenced by both genetic and environmental factor. Folic acid (FA) supplementation is an effective for prevention of a proportion of NTDs, however, the mechanism remains unclear. In this study, our data demonstrated genome-wide enrichment of 5-hydroxymethylcytosine (5hmC) modification on active transcriptional start sites (TSS) and decreased 5-methylcytosine (5mC) binding to TSS under folate deficiency in mESCs (mouse embryonic stem cells). Furthermore, folate deficiency promoted 5hmC enrichment enhancer histone 3 lysine 27 acetylation (H3K27ac) binding to Shh pathway genes in mESCs. Upregulation of Shh target genes was observed in mouse brain tissue under low levels of maternal serum folate, along with increased expression of 5-methylcytosine dioxygenase Tet1 levels. Taken together, we found that folate deficiency promoted DNA demethylation and enriched 5hmC through recruitment of H3K27ac to activate the Shh signaling pathway. These results suggest that the 5hmC modification increases concomitantly with a positive correlation to Shh gene expression in folate deficiency-induced mouse NTDs.

Pathogenesis of chronic obstructive pulmonary disease: understanding the contributions of gene-environment interactions across the lifespan

The traditional view of chronic obstructive pulmonary disease (COPD) as a self-inflicted disease caused by tobacco smoking in genetically susceptible individuals has been challenged by recent research findings. COPD can instead be understood as the potential end result of the accumulation of gene-environment interactions encountered by an individual over the life course. Integration of a time axis in pathogenic models of COPD is necessary because the biological responses to and clinical consequences of different exposures might vary according to both the age of an individual at which a given gene-environment interaction occurs and the cumulative history of previous gene-environment interactions. Future research should aim to understand the effects of dynamic interactions between genes (G) and the environment (E) by integrating information from basic omics (eg, genomics, epigenomics, proteomics) and clinical omics (eg, phenomics, physiomics, radiomics) with exposures (the exposome) over time (T)-an approach that we refer to as GETomics. In the context of this approach, we argue that COPD should be viewed not as a single disease, but as a clinical syndrome characterised by a recognisable pattern of chronic symptoms and structural or functional impairments due to gene-environment interactions across the lifespan that influence normal lung development and ageing.

Growth, puberty and testicular function in boys born small for gestational age with a nonspecific disorder of sex development

OBJECTIVE

Being born small for gestational age (SGA) is frequently associated with unexplained disorders of sex development (nonspecific DSD) in boys. Little is known about their future growth, puberty and testicular function. Our objective is to determine the long-term endocrine outcome of boys born SGA who have a nonspecific DSD.

DESIGN

Boys with a nonspecific DSD born SGA and appropriate for GA (AGA) were retrieved through the International Disorders of Sex Development registry and retrospective data collected, based on a spreadsheet containing 102 items.

PATIENTS AND MEASUREMENTS

In total, 179 boys were included, of which 115 were born SGA and 64 were born AGA. Their growth and pubertal development were compared. Serum LH, FSH, testosterone, AMH and inhibin B levels in infancy and puberty were analysed to assess testicular function.

RESULTS

At 2 years of age, 30% of SGA boys had incomplete or absent catch-up growth. Boys born SGA also had higher LH during minipuberty and lower testosterone in stimulation tests (p = 0.037 and 0.040, respectively), as compared to boys born AGA. No differences were observed in timing or course of puberty or end-pubertal hormone levels.

CONCLUSIONS

Almost one out of three SGA boys with a nonspecific DSD experiences insufficient catch-up growth. In addition, our data suggest dysfunction of infantile Leydig cells or altered regulation of the hypothalamic-pituitary-gonadal axis in SGA boys during childhood. Sex steroid production during puberty seems unaffected.

The role of DNA methylation in syndromic and non-syndromic congenital heart disease

Congenital heart disease (CHD) is a common structural birth defect worldwide, and defects typically occur in the walls and valves of the heart or enlarged blood vessels. Chromosomal abnormalities and genetic mutations only account for a small portion of the pathogenic mechanisms of CHD, and the etiology of most cases remains unknown. The role of epigenetics in various diseases, including CHD, has attracted increased attention. The contributions of DNA methylation, one of the most important epigenetic modifications, to CHD have not been illuminated. Increasing evidence suggests that aberrant DNA methylation is related to CHD. Here, we briefly introduce DNA methylation and CHD and then review the DNA methylation profiles during cardiac development and in CHD, abnormalities in maternal genome-wide DNA methylation patterns are also described. Whole genome methylation profile and important differentially methylated genes identified in recent years are summarized and clustered according to the sample type and methodologies. Finally, we discuss the novel technology for and prospects of CHD-related DNA methylation.

Placental Epigenome-Wide Association Study Identified Loci Associated with Childhood Adiposity at 3 Years of Age

The aim of this study was to identify placental DNA methylation (DNAm) variations associated with adiposity at 3 years of age. We quantified placental DNAm using the Infinium MethylationEPIC BeadChips. We assessed associations between DNAm at single-CpGs and skinfold thickness using robust linear regression models adjusted for gestational age, child's sex, age at follow-up and cellular heterogeneity. We sought replication of DNAm association with child adiposity in an independent cohort. We quantified placental mRNA levels for annotated gene using qRT-PCR and tested for correlation with DNAm. Lower DNAm at cg22593959 and cg22436429 was associated with higher adiposity (β = -1.18, q = 0.002 and β = -0.82, q = 0.04). The cg22593959 is located in an intergenic region (chr7q31.3), whereas cg22436429 is within the TFAP2E gene (1p34.3). DNAm at cg22593959 and cg22436429 was correlated with mRNA levels at FAM3C (r_s = -0.279, p = 0.005) and TFAP2E (r_s = 0.216, p = 0.03). In an independent cohort, the association between placental DNAm at cg22593959 and childhood adiposity was of similar strength and direction (β = -3.8 ± 4.1, p = 0.36), yet non-significant. Four genomic regions were also associated with skinfold thickness within FMN1, MAGI2, SKAP2 and BMPR1B genes. We identified placental epigenetic variations associated with adiposity at 3 years of age suggesting that childhood fat accretion patterns might be established during fetal life.

Current Insights into the Role of the Growth Hormone-Insulin-Like Growth Factor System in Short Children Born Small for Gestational Age

BACKGROUND

The reason for the insufficient catch-up growth seen in 10% of children born small for gestational age (SGA) is poorly understood. Disturbances in the growth hormone (GH) - insulin-like growth factor (IGF) axis might underlie this failure to show sufficient catch-up growth.

CONCLUSION

This review summarizes insights gained in the molecular and (epi) genetic mechanisms of the GH-IGF axis in short children born SGA. The most notable anomalies of the IGF system are the lowered IGF-I levels in both cord blood and the placenta, and the increased expression of IGF-binding proteins (IGFBP)-1 and IGFBP-2, which inhibit IGF-I, in the placenta of SGA neonates. These observations suggest a decreased bioactivity of IGF-I in utero. IGF-I levels remain reduced in SGA children with short stature, as well as IGFBP-3 and acid-labile subunit levels. Proteolysis of IGFBP-3 appears to be increased.

One-Carbon Metabolism Links Nutrition Intake to Embryonic Development via Epigenetic Mechanisms

Beyond energy production, nutrient metabolism plays a crucial role in stem cell lineage determination. Changes in metabolism based on nutrient availability and dietary habits impact stem cell identity. Evidence suggests a strong link between metabolism and epigenetic mechanisms occurring during embryonic development and later life of offspring. Metabolism regulates epigenetic mechanisms such as modifications of DNA, histones, and microRNAs. In turn, these epigenetic mechanisms regulate metabolic pathways to modify the metabolome. One-carbon metabolism (OCM) is a crucial metabolic process involving transfer of the methyl groups leading to regulation of multiple cellular activities. OCM cycles and its related micronutrients are ubiquitously present in stem cells and feed into the epigenetic mechanisms. In this review, we briefly introduce the OCM process and involved micronutrients and discuss OCM-associated epigenetic modifications, including DNA methylation, histone modification, and microRNAs. We further consider the underlying OCM-mediated link between nutrition and epigenetic modifications in embryonic development.

RNA-seq of Isolated Chromaffin Cells Highlights the Role of Sex-Linked and Imprinted Genes in Adrenal Medulla Development

Adrenal chromaffin cells and sympathetic neurons synthesize and release catecholamines, and both cell types are derived from neural crest precursors. However, they have different developmental histories, with sympathetic neurons derived directly from neural crest precursors while adrenal chromaffin cells arise from neural crest-derived cells that express Schwann cell markers. We have sought to identify the genes, including imprinted genes, which regulate the development of the two cell types in mice. We developed a method of separating the two cell types as early as E12.5, using differences in expression of enhanced yellow fluorescent protein driven from the tyrosine hydroxylase gene, and then used RNA sequencing to confirm the characteristic molecular signatures of the two cell types. We identified genes differentially expressed by adrenal chromaffin cells and sympathetic neurons. Deletion of a gene highly expressed by adrenal chromaffin cells, NIK-related kinase, a gene on the X-chromosome, results in reduced expression of adrenaline-synthesizing enzyme, phenyl-N-methyl transferase, by adrenal chromaffin cells and changes in cell cycle dynamics. Finally, many imprinted genes are up-regulated in chromaffin cells and may play key roles in their development.

Inflammatory Diseases and Growth: Effects on the GH-IGF Axis and on Growth Plate

This review briefly describes the most common chronic inflammatory diseases in childhood, such as cystic fibrosis (CF), inflammatory bowel diseases (IBDs), juvenile idiopathic arthritis (JIA), and intrauterine growth restriction (IUGR) that can be considered, as such, for the changes reported in the placenta and cord blood of these subjects. Changes in growth hormone (GH) secretion, GH resistance, and changes in the insulin-like growth factor (IGF) system are described mainly in relationship with the increase in nuclear factor-κB (NF-κB) and pro-inflammatory cytokines. Changes in the growth plate are also reported as well as a potential role for microRNAs (miRNAs) and thus epigenetic changes in chronic inflammation. Many mechanisms leading to growth failure are currently known; however, it is clear that further research in the field is still warranted.

Low and high dietary folic acid levels perturb postnatal cerebellar morphology in growing rats

The brain is particularly sensitive to folate metabolic disturbances, because methyl groups are critical for brain functions. This study aimed to investigate the effects of different dietary levels of folic acid (FA) on postnatal cerebellar morphology, including the architecture and organisation of the various layers. A total of forty male OFA rats (a Sprague-Dawley strain), 5 weeks old, were classified into the following four dietary groups: FA deficient (0 mg/kg FA); FA supplemented (8 mg/kg FA); FA supra-supplemented (40 mg/kg FA); and control (2 mg/kg FA) (all n 10 per group). Rats were fed ad libitum for 30 d. The cerebellum was quickly removed and processed for histological and immunohistochemical analysis. Slides were immunostained for glial fibrillary acidic protein (to label Bergmann glia), calbindin (to label Purkinje cells) and NeuN (to label post-mitotic neurons). Microscopic analysis revealed two types of defect: partial disappearance of fissures and/or neuronal ectopia, primarily in supra-supplemented animals (incidence of 80 %, P≤0·01), but also in deficient and supplemented groups (incidence of 40 %, P≤0·05), compared with control animals. The primary fissure was predominantly affected, sometimes accompanied by defects in the secondary fissure. Our findings show that growing rats fed an FA-modified diet, including both deficient and supplemented diets, have an increased risk of disturbances in cerebellar corticogenesis. Defects caused by these diets may have functional consequences in later life. The present study is the first to demonstrate that cerebellar morphological defects can arise from deficient, as well as high, FA levels in the diet.

The role of environmental exposures as risk factors for bipolar disorder: A systematic review of longitudinal studies

BACKGROUND

The role of environmental risk factors in the development of bipolar disorder (BD) is not well characterized. We evaluate the prevalence, duration, and predictive value of environmental exposures for BD in longitudinal studies.

METHODS

We conducted a systematic search of PubMed, Scopus and PsychINFO databases until April 01, 2015, using the following words in combination: prenatal exposure; maternal exposure; trauma; childhood abuse; alcoholism; cannabis; smoking; cocaine; central stimulants; opioids; uv light; pollution; global warming; vitamin d AND bipolar disorder. Additional references were obtained through cross-referencing. We included (1) longitudinal cohort studies or case-control studies nested within longitudinal designs; (2) studies of subjects without lifetime BD diagnoses at initial assessment and a diagnosis of BD at follow-up by clinical or structured assessment. Familial-risk studies were excluded. We tabulated details of study-design, exposure, diagnostic criteria, risk of bipolar disorder expressed as odd ratio (OR), relative risk (RR) or hazard ratio (HR).

RESULTS

Of 2119 studies found, 22 met inclusion criteria. Risk factors identified can be grouped in 3 clusters: neurodevelopment (maternal influenza during pregnancy; indicators of fetal development), substances (cannabis, cocaine, other drugs - opioids, tranquilizers, stimulants, sedatives), physical/psychological stress (parental loss, adversities, abuses, brain injury).

LIMITATIONS

Heterogeneity of designs and methodology prevented the use of meta-analysis of the findings; studies did not provide sensitivity, specificity and predictive value of the risk factors identified; case-control studies classify cases based on diagnostic membership, but do not control for familial or genetic liability; methods for determining the exposures varied among studies.

CONCLUSION

Only preliminary evidence exists that exposure to viral infection, substances or trauma increase the likelihood of BD. Given the limited data available, the specificity, sensitivity and predictive value could not be computed. As exposures are sometimes amenable to prevention, further research is needed.

The Epigenetic Effects of Prenatal Cadmium Exposure

Prenatal exposure to the highly toxic and common pollutant cadmium has been associated with adverse effects on child health and development. However, the underlying biological mechanisms of cadmium toxicity remain partially unsolved. Epigenetic disruption due to early cadmium exposure has gained attention as a plausible mode of action, since epigenetic signatures respond to environmental stimuli and the fetus undergoes drastic epigenomic rearrangements during embryogenesis. In the current review, we provide a critical examination of the literature addressing prenatal cadmium exposure and epigenetic effects in human, animal, and in vitro studies. We conducted a PubMed search and obtained eight recent studies addressing this topic, focusing almost exclusively on DNA methylation. These studies provide evidence that cadmium alters epigenetic signatures in the DNA of the placenta and of the newborns, and some studies indicated marked sexual differences for cadmium-related DNA methylation changes. Associations between early cadmium exposure and DNA methylation might reflect interference with de novo DNA methyltransferases. More studies, especially those including environmentally relevant doses, are needed to confirm the toxicoepigenomic effects of prenatal cadmium exposure and how that relates to the observed health effects of cadmium in childhood and later life.

Reprogramming: A Preventive Strategy in Hypertension Focusing on the Kidney

Adulthood hypertension can be programmed in response to a suboptimal environment in early life. However, developmental plasticity also implies that one can prevent hypertension in adult life by administrating appropriate compounds during early development. We have termed this reprogramming. While the risk of hypertension has been assessed in many mother-child cohorts of human developmental programming, interventions necessary to prove causation and provide a reprogramming strategy are lacking. Since the developing kidney is particularly vulnerable to environmental insults and blood pressure is determined by kidney function, renal programming is considered key in developmental programming of hypertension. Common pathways, whereby both genetic and acquired developmental programming converge into the same phenotype, have been recognized. For instance, the same reprogramming interventions aimed at shifting nitric oxide (NO)-reactive oxygen species (ROS) balance, such as perinatal citrulline or melatonin supplements, can be protective in both genetic and developmentally programmed hypertension. Furthermore, a significantly increased expression of gene Ephx2 (soluble epoxide hydrolase) was noted in both genetic and acquired animal models of hypertension. Since a suboptimal environment is often multifactorial, such common reprogramming pathways are a practical finding for translation to the clinic. This review provides an overview of potential clinical applications of reprogramming strategies to prevent programmed hypertension. We emphasize the kidney in the following areas: mechanistic insights from human studies and animal models to interpret programmed hypertension; identified risk factors of human programmed hypertension from mother-child cohorts; and the impact of reprogramming strategies on programmed hypertension from animal models. It is critical that the observed effects on developmental reprogramming in animal models are replicated in human studies.

Dietary Intakes of Folic Acid and Methionine in Early Childhood Are Associated with Body Composition at School Age

BACKGROUND

Deficiency of vitamin B-6, vitamin B-12, folate, folic acid, or methionine may lead to dysregulation of DNA methylation, which might lead to disturbed energy and lipid metabolism.

OBJECTIVE

We aimed to explore whether intakes of vitamin B-6, vitamin B-12, folate, folic acid, and methionine at 1 y are associated with measures of growth and body composition at the age of 6 y.

METHODS

This study was performed in 2922 children participating in The Generation R Study, a population-based prospective cohort study. Dietary intakes of vitamins B-6 and B-12, folate, folic acid, and methionine were assessed at a median age of 12.9 mo by using a validated food-frequency questionnaire. At the age of 6 y, height and weight were measured, and body mass index (BMI; in kg/m(2)) was calculated. Body fat was measured with dual-energy X-ray absorptiometry, and body fat percentage and the ratio of android fat mass to gynoid fat mass (android:gynoid) were calculated.

RESULTS

In models adjusted for maternal and child characteristics, children with folic acid intakes in the highest tertile had a 0.16 SD score (SDS) lower weight (95% CI: -0.31, -0.02 SDS) and a 0.14 SDS lower BMI (95% CI: -0.26, -0.01 SDS) than children in the lowest tertile. Children with vitamin B-12 intakes in the highest tertile had a 0.13 SDS higher android:gynoid (95% CI: 0.00, 0.25 SDS) than children in the lowest tertile. In addition, children with intakes in the highest tertile of methionine had a 0.09 SDS higher BMI (95% CI: 0.01, 0.17) and a 0.12 SDS higher android:gynoid (95% CI: 0.02, 0.22) than children in the lowest tertile. Vitamin B-6 and folate intakes were not associated with any of the body composition outcomes measured.

CONCLUSIONS

In this population of children, early high folic acid intakes were associated with a lower body weight and BMI at the age of 6 y. In contrast, early higher methionine intakes were associated with unfavorable body composition at the age of 6 y. Future studies should investigate long-term consequences of these outcomes on health.

Novel DNA methylation profiles associated with key gene regulation and transcription pathways in blood and placenta of growth-restricted neonates

Fetal growth is determined by the feto-placental genome interacting with the maternal in utero environment. Failure of this interplay leads to poor placental development and fetal growth restriction (FGR), which is associated with future metabolic disease. We investigated whether whole genome methylation differences existed in umbilical cord blood and placenta, between gestational-matched, FGR, and appropriately grown (AGA) neonates. Using the Infinium HumanMethylation450 BeadChip®, we found that DNA from umbilical cord blood of FGR born at term (n = 19) had 839 differentially methylated positions (DMPs) that reached genome-wide significance compared with AGA (n = 18). Using gestational age as a continuous variable, we identified 76,249 DMPs in cord blood (adj. P < 0.05) of which 121 DMPs were common to the 839 DMPs and were still evident when comparing 12 FGR with 12 AGA [39.9 ± 1.2 vs. 40.0 ± 1.0 weeks (mean ± SD), respectively]. A total of 53 DMPs had a β methylation difference >10% and 25 genes were co-methylated more than twice within 1000 base pairs. Gene Ontology (GO) analysis of DMPs supported their involvement in gene regulation and transcription pathways related to organ development and metabolic function. A similar profile of DMPs was found across different cell types in the cord blood. At term, no DMPs between FGR and AGA placentae reached genome-wide significance, validated with an external dataset. GO analysis of 284 pre-term, placental DMPs associated with autophagy, oxidative stress and hormonal responses. Growth restricted neonates have distinct DNA methylation profiles in pre-term placenta and in cord blood at birth, which may predispose to future adult disease.

Early-life Exposure to Endocrine Disrupting Chemicals and Later-life Health Outcomes: An Epigenetic Bridge?

A growing body of evidence demonstrates that adverse events early in development, and particularly during intrauterine life, may program risks for diseases in adult life. Increasing evidence has been accumulated indicating the important role of epigenetic regulation including DNA methylation, histone modifications and miRNAs in developmental programming. Among the environmental factors which play an important role in programming of chronic pathologies, the endocrine-disrupting chemicals (EDCs) that have estrogenic, anti-estrogenic, and anti-androgenic activity are of specific concern because the developing organism is extremely sensitive to perturbation by substances with hormone-like activity. Among EDCs, there are many substances that are constantly present in the modern human environment or are in widespread use, including dioxin and dioxin-like compounds, phthalates, agricultural pesticides, polychlorinated biphenyls, industrial solvents, pharmaceuticals, and heavy metals. Apart from their common endocrine active properties, several EDCs have been shown to disrupt developmental epigenomic programming. The purpose of this review is to provide a summary of recent research findings which indicate that exposure to EDCs during in-utero and/or neonatal development can cause long-term health outcomes via mechanisms of epigenetic memory.

Maternal preconception body mass index and offspring cord blood DNA methylation: exploration of early life origins of disease

Maternal obesity is associated with a variety of common diseases in the offspring. One possible underlying mechanism could be maternal obesity induced alterations in DNA methylation. However, this hypothesis is yet to be tested. We performed epigenomic mapping of cord blood among 308 Black mother-infant pairs delivered at term at the Boston Medical Center using the Illumina HumanMethylation27 BeadChip. Linear regression and pathway analyses were conducted to evaluate the associations between DNA methylation levels and prepregnancy maternal BMI (<25, 25-30, ≥30 kg/m(2) ). The methylation levels of 20 CpG sites were associated with maternal BMI at a significance level of P-value <10(-4) in the overall sample, and boys and girls, separately. One CpG site remained statistically significant after correction for multiple comparisons (FDR corrected P-value = 0.04) and was annotated to a potential cancer gene, ZCCHC10. Some of the other CpG site annotated genes appear to be critical to the development of cancers and cardiovascular diseases (i.e., WNT16, C18orf8, ANGPTL2, SAPCD2, ADCY3, PRR16, ERBB2, DOK2, PLAC1). Significant findings from pathway analysis, such as infectious and inflammatory and lipid metabolism pathways, lends support for the potential impact of maternal BMI on the above stated disorders. This study demonstrates that prepregnancy maternal BMI might lead to alterations in offspring DNA methylation in genes relevant to the development of a range of complex chronic diseases, providing evidence of trans-generational influence on disease susceptibility via epigenetic mechanism.

Gestational methyl donor deficiency alters key proteins involved in neurosteroidogenesis in the olfactory bulbs of newborn female rats and is associated with impaired olfactory performance

Gestational methyl donor deficiency (MDD) leads to growth retardation as well as to cognitive and motor disorders in 21-d-old rat pups. These disorders are related to impaired neurogenesis in the cerebral neurogenic areas. Olfactory bulbs (OB), the main target of neuronal progenitors originating from the subventricular zone, play a critical role during the postnatal period by allowing the pups to identify maternal odour. We hypothesised that growth retardation could result from impaired suckling due to impaired olfactory discrimination through imbalanced apoptosis/neurogenesis in the OB. Since neurosteroidogenesis modulates neurogenesis in OB, in the present study, we investigated whether altered neurosteroidogenesis could explain some these effects. Pups born to dams fed a normal diet (n 24) and a MDD diet (n 27) were subjected to olfactory tests during the lactation and weaning periods (n 24 and 20, respectively). We studied the markers of apoptosis/neurogenesis and the expression levels of the key neurosteroidogenic enzyme aromatase, the cholesterol-transfer protein StAR (steroidogenic acute regulatory protein) and the ERα oestrogen receptor and the content of oestradiol in OB. The 21-d-old MDD female pups displayed lower body weight and impaired olfactory discrimination when compared with the control pups. MDD led to greater homocysteine accumulation and more pronounced apoptosis, along with impaired cell proliferation in the OB of female pups. The expression levels of aromatase, StAR and ERα as well as the content of oestradiol were lower in the OB of the MDD female pups than in those of the control female pups. In conclusion, gestational MDD may alter olfactory discrimination performances by affecting neurogenesis, apoptosis and neurosteroidogenesis in OB in a sex-dependent manner. It may be involved in growth retardation through impaired suckling.

Fetal growth and schizophrenia: a nested case-control and case-sibling study

The association between low birth weight and schizophrenia has been suggested by many studies. Small for gestational age (SGA) is a measure used as a proxy for intrauterine growth restriction. We aim to examine if children who are born SGA are at increased risk of developing schizophrenia and whether an association may be explained by factors shared among siblings. We linked 3 population-based registers: the Danish National Medical Birth Register, the Danish Psychiatric Central Register, and the Danish Civil Registration register to identify all persons born between 1978 and 2000. A nested case-control study and a case-sibling study design were used. There were 4650 cases of schizophrenia. Incidence rate ratios (IRRs) were estimated using conditional logistic regression. SGA was defined as the lowest 10th birth weight percentile for a given sex and gestational age. SGA was associated with an IRR of 1.23 (95% CI: 1.11-1.37) for schizophrenia in the case-control study. An IRR of 1.28 (95% CI: 0.97-1.68) was found in the case-sibling study. There is a modest association between SGA and schizophrenia. Our results indicate that this association is due to an independent effect of factors associated with low birth weight for gestational age per se, rather than other factors shared by siblings.

The role of folic acid in fetal programming of birth phenotypes and early human development: a biopsychosocial perspective

Preterm birth, low birthweight, intrauterine growth retardation and small for gestational age are birth phenotypes that significantly contribute to life-long morbidity and mortality. This review examines the epidemiologic and biologic evidence of folic acid (FA) as a potential population-based intervention to curtail some adverse birth phenotypic expressions, and by extension, their later physical and neurodevelopmental consequences. We outlined a feto-placental adaptation categorization taking into account how prenatal insults may be encoded in fetal development, the adaptive success of the feto-placental response, and subsequent expression in the health of the fetus. Although there are plausible biological pathways that can be implicated, we found that the epidemiological evidence on the role of perinatal FA nutriture and fetal programming of adverse birth phenotypes is still inconclusive. Because biologic and epidemiological considerations alone do not suffice in deciphering the utility of FA in averting adverse birth phenotypes, we proposed a biopsychosocial model that takes into account multi-layered psychosocial contexts for improving subsequent research studies in this area.

Male specific association between xenoestrogen levels in placenta and birthweight

BACKGROUND

Fetal exposure to endocrine disrupting chemicals may increase the risk for adverse health effects at birth or later in life.

OBJECTIVES

The objective of this study is to analyze the combined effect of xenoestrogens on reproductive and perinatal growth outcomes (child birthweight, early rapid growth and body mass index (BMI) at 14 months) using the biomarker total effective xenoestrogen burden (TEXB).

METHODS

490 placentas were randomly collected in the Spanish prospective birth cohort Environment and Childhood (INMA) project. TEXB was used to assess the estrogenicity of placental samples in two fractions: that largely attributable to environmental organohalogenated xenoestrogens (TEXB-alpha), and that mostly due to endogenous estrogens (TEXB-beta), both expressed in estrogen equivalent units (Eeq) per gram of tissue. Linear or logistic regression models were performed adjusting for cohort and confounders. Sex interactions were investigated.

RESULTS

The median TEXB-alpha level was 0.76 pM Eeq/g (interquartile range (iqr): 1.14). In multivariate models, higher TEXB-alpha levels (third tertile, >1.22 pM Eeq/g; iqr: 1.73) were associated with increased birthweight in boys but not in girls (β=148.2 g, 95% CI: 14.01, 282.53, p(int)=0.057). Additionally, higher TEXB-alpha values in boys were related with a lower risk of early rapid growth (OR=0.37; 95% CI: 0.15, 0.88) and with a non significant association with larger BMI z-scores at 14 months of age (β=0.29; 95% CI: -0.11, 0.69).

CONCLUSIONS

These findings suggest that prenatal exposure to xenoestrogens may increase birthweight in boys, which might have an impact on child obesity and other later health outcomes.

Obesity and endocrine dysfunction programmed by maternal smoking in pregnancy and lactation

Obesity is a global epidemic, and maternal smoking has been shown to be associated with the development of childhood obesity. Overall, approximately 40% of children worldwide are exposed to tobacco smoke at home. It is well known that environmental changes within a critical window of development, such as gestation or lactation, can initiate permanent alterations in metabolism that lead to diseases in adulthood, a phenomenon called programming. It is known that programming is based on epigenetic alterations (changes in DNA methylation, histone acetylation, or small interfering RNA expression) that change the expression pattern of several genes. However, little is known concerning the mechanisms by which smoke exposure in neonatal life programs the adipose tissue and endocrine function. Here, we review several epidemiological and experimental studies that confirm the association between maternal nicotine or tobacco exposure during gestation or lactation and the development of obesity and endocrine dysfunction. For example, a positive correlation was demonstrated in rodents between increased serum leptin in the neonatal period and exposure of the mothers to nicotine during lactation, and the further development of leptin and insulin resistance, and thyroid and adrenal dysfunction, in adulthood in the same offspring. Thus, a smoke-free environment during the lactation period is essential to improving health outcomes in adulthood and reducing the risk for future diseases. An understanding of the pathophysiological mechanisms underlying the effects of smoking on programming can provide new insights into therapeutic strategies for obesity.

Perinatal conditions and parental age at birth as risk markers for subsequent suicide attempt and suicide: a population based case-control study

Restricted fetal growth and young maternal age have been associated with increased risk of suicidal behaviour later in life. Research investigating the independent and interacting effects of these risk factors with parental mental health and socio-economic status is scarce. A case-control study was effected through record linkage between Swedish registers. Individuals born 1973-1983 who were hospitalized due to a suicide attempt (n = 17,159) or committed suicide (n = 1,407) were matched to ≤10 controls by sex, month and county of birth. Controlling for parental conditions, significantly increased odds ratios (OR) for suicide attempt were found for low birth weight (OR = 1.12, 95 % CI 1.01-1.25), short birth length (OR = 1.15, 95 % CI 1.08-1.22), short and light for gestational age (OR = 1.23, 95 % CI: 1.10-1.38), short but not light for gestational age (OR = 1.18, 95 % CI: 1.09, 1.29), teenage motherhood (OR = 1.66, 95 % CI 1.53-1.80), young fatherhood (OR = 1.33, 95 % CI 1.27-1.39) and multiparity (OR = 1.40, 95 % CI 1.31-1.50). For completed suicide, increased odds ratios were found for low birth weight (OR = 1.65, 95 % CI 1.16-2.35), teenage motherhood (OR = 1.44, 95 % CI 1.09-1.90) and young fatherhood (OR = 1.20, 95 % CI 1.02-1.41). There was a synergy effect between teenage motherhood and parental psychiatric inpatient care with regard to suicide attempt in offspring [synergy index = 1.53 (95 % CI 1.27-1.84)]. Low birth weight and length, and short and light for gestational age may increase the risk of subsequent suicidal behaviour, and more research is needed to investigate underlying mechanisms. Public health implications from this study include measures to improve pre- and perinatal parental mental health, particularly in teenage pregnancies.

Factors influencing epigenetic mechanisms and related diseases

It is becoming clear that epigenetic mechanisms are associated with disease. To date, a myriad of epigenetic alterations, including altered DNA methylation and aberrant histone post-translational modifications, have been linked with various conditions. The most widely investigated example is the link between aberrant DNA methylation and malignancy that has lead to the clinical use of the DNA methyltransferase inhibitors, azacitidine and decitabine, for the treatment of myelodysplastic syndromes. Similarly, defective histone acetylation status has been associated with malignancy, providing the basis for the clinical use of the histone deacetylase inhibitors suberoylanilide hydroxamic acid and depsipeptide for the treatment of cutaneous T-cell lymphoma. In addition, there is an emerging association between perturbed fetal epigenetic programming and developmental origins of disease due to both nutritional and environmental factors. In particular, epigenetic events associated with metabolic syndrome have been identified. Related epigenetic mechanisms as well potential pharmacological and dietary interventions at critical periods of development form a large part of the discussion in this Forum. Further, this Forum provides an in-depth account of the association between epigenetic mechanisms and carcinogenesis with a focus on disease prevention with dietary chromatin-modifying compounds. Finally, the association between aberrant epigenetic events and neurodegenerative conditions, such as Alzheimer's disease (AD), is becoming apparent. A research article in this Forum identifies a potential new polymorphism associated with one-carbon metabolism that may contribute to the pathogenesis of AD. Overall, this Forum provides a detailed account of known epigenetic processes in developmental programming and human disease.