Impact of Maternal Aspirin Therapy on Neonatal Epigenetic Patterns.

Prenatal arsenic exposure is associated with increased risk of disease in adulthood. This has led to considerable interest in arsenic’s ability to disrupt fetal programming. Many studies report that arsenic exposure alters DNA methylation in whole blood but these studies did not adjust for cell mixture. In this study, we examined the relationship between arsenic in maternal drinking water collected ≤ 16 weeks gestational age and DNA methylation in cord blood (n = 44) adjusting for leukocyte-tagged differentially methylated regions. DNA methylation was quantified using the Infinium HumanMethylation 450 BeadChip array. Recursively partitioned mixture modeling examined the relationship between arsenic and methylation at 473,844 CpG sites. Median arsenic concentration in water was 12 µg/L (range < 1- 510 µg/L). Log10 arsenic was associated with altered DNA methylation across the epigenome (P = 0.002); however, adjusting for leukocyte distributions attenuated this association (P = 0.013). We also observed that arsenic had a strong effect on the distribution of leukocytes in cord blood. In adjusted models, every log10 increase in maternal drinking water arsenic exposure was estimated to increase CD8+ T cells by 7.4% (P = 0.0004) and decrease in CD4+ T cells by 9.2% (P = 0.0002). These results show that prenatal exposure to arsenic had an exposure-dependent effect on specific T cell subpopulations in cord blood and altered DNA methylation in cord blood. Future research is needed to determine if these small changes in DNA methylation alter gene expression or are associated with adverse health effects.

Background: Maternal smoking is related to multiple adverse health outcomes in children. We previously reported an association between maternal smoking during pregnancy and differential DNA methylation in newborn cord bloods for CpG sites (CpGs) in genes involved in the aryl hydrocarbon receptor signaling pathway and key developmental processes. However, it remains unclear whether these modifications to the infant epigenome reflect in utero exposures only or the inheritance of epigenetic marks from the mother. Aims: We evaluated the association between maternal smoking before or during pregnancy and DNA methylation for 21 CpGs previously identified as differentially methylated in response to maternal smoking in 1,047 newborn cord bloods from the Norwegian Mother and Child Cohort Study (MoBa). Methods: Maternal self-report of smoking as well as maternal plasma cotinine measured during pregnancy were used to distinguish mothers into four groups (never smokers, former smokers, smokers who smoked during pregnancy but quit by 18 weeks, and active smokers throughout pregnancy). The association between smoking and methylation was assessed using linear regression. Results: Having a mother who formerly smoked was not associated with differential methylation in cord blood for any of the 21 CpGs (at FDR of 0.05). Quitting during pregnancy was also not significantly associated with differential methylation (at FDR of 0.05) although methylation differences were larger than those for former smokers compared to never smokers. Only active smoking throughout pregnancy was statistically significantly associated with differential methylation (at FDR of 0.05). Conclusions: Differential methylation in newborn cord blood at the 21 CpGs that we previously found to be related to maternal smoking in pregnancy was only observed where mothers smoked during pregnancy. These findings suggest that DNA methylation at these locations in the infant epigenome reflects in utero exposure rather than epigenetic inheritance of smoking-related modifications in the mother.

Gestational weight gain in pregnant women with obesity is associated with cord blood DNA methylation, which partially mediates offspring anthropometrics

ObjectiveWe investigated whether prepregnancy BMI (prePregBMI) in women with obesity was associated with differential DNA methylation (DNAm) in cord blood (CB) and whether DNAm may mediate the association of prePregBMI and early childhood BMI z score (BMIz).MethodsFrom the Treatment of Obese Pregnant Women (TOP) study, 232 mother–child pairs were included. We conducted an epigenome‐wide association study on prePregBMI and CB DNAm (450k array), followed by causal mediation analyses to test whether DNAm may mediate effects of prePregBMI on BMIz at age 36 months (BMIz36).ResultsDNAm at 5345 CpG sites annotated to 2842 genes, which were overrepresented in biological processes linked to carbohydrate metabolism and plasma lipoprotein particle clearance, was associated with prePregBMI (false discovery rate < 10%). Causal mediation analyses of 168 methylation sites associated with BMIz36 (p < 0.05) and overlapping with the 5345 prePregBMI‐associated sites identified two sites on SYT7 and DEAF1, partially mediating the effect of prePregBMI on BMIz36 (p ≤ 0.01). After cross‐validation, a methylation risk score including these two sites could predict the highest quartile of BMIz36 and fat mass (in grams) with area under the curve = 0.72 (95% CI: 0.58–0.85) and area under the curve = 0.71 (95% CI: 0.58–0.85), respectively.ConclusionsCB DNAm at birth may partially mediate effects of prePregBMI on early childhood BMIz36, supporting its plausible role in influencing individual future obesity risk.

Background: There is increasing epidemiologic evidence that arsenic exposure in utero, even at low levels found throughout much of the world, is associated with adverse reproductive outcomes and may contribute to long-term health effects. Animal models, in vitro studies, and human cancer data suggest that arsenic may induce epigenetic alterations, specifically by altering patterns of DNA methylation.Objectives: In this study we aimed to identify differences in DNA methylation in cord blood samples of infants with in utero, low-level arsenic exposure.Methods: DNA methylation of cord-blood derived DNA from 134 infants involved in a prospective birth cohort in New Hampshire was profiled using the Illumina Infinium Methylation450K array. In utero arsenic exposure was estimated using maternal urine samples collected at 24–28 weeks gestation. We used a novel cell mixture deconvolution methodology for examining the association between inferred white blood cell mixtures in infant cord blood and in utero arsenic exposure; we also examined the association between methylation at individual CpG loci and arsenic exposure levels.Results: We found an association between urinary inorganic arsenic concentration and the estimated proportion of CD8+ T lymphocytes (1.18; 95% CI: 0.12, 2.23). Among the top 100 CpG loci with the lowest p-values based on their association with urinary arsenic levels, there was a statistically significant enrichment of these loci in CpG islands (p = 0.009). Of those in CpG islands (n = 44), most (75%) exhibited higher methylation levels in the highest exposed group compared with the lowest exposed group. Also, several CpG loci exhibited a linear dose-dependent relationship between methylation and arsenic exposure.Conclusions: Our findings suggest that in utero exposure to low levels of arsenic may affect the epigenome. Long-term follow-up is planned to determine whether the observed changes are associated with health outcomes.

Ambient air pollution during pregnancy and DNA methylation in umbilical cord blood, with potential mediation of associations with infant adiposity: The Healthy Start study

BackgroundPhthalates and bisphenols are non-persistent endocrine disrupting chemicals that are ubiquitously present in our environment and may have long-lasting health effects following fetal exposure. A potential mechanism underlying these exposure–outcome relationships is differential DNA methylation. Our objective was to examine the associations of maternal phthalate and bisphenol concentrations during pregnancy with DNA methylation in cord blood using a chemical mixtures approach.MethodsThis study was embedded in a prospective birth cohort study in the Netherlands and included 306 participants. We measured urine phthalates and bisphenols concentrations in the first, second and third trimester. Cord blood DNA methylation in their children was processed using the Illumina Infinium HumanMethylation450 BeadChip using an epigenome-wide association approach. Using quantile g-computation, we examined the association of increasing all mixture components by one quartile with cord blood DNA methylation.ResultsWe did not find evidence for statistically significant associations of a maternal mixture of phthalates and bisphenols during any of the trimesters of pregnancy with DNA methylation in cord blood (all p values > 4.01 * 10–8). However, we identified one suggestive association (p value < 1.0 * 10–6) of the first trimester maternal mixture of phthalates and bisphenols and three suggestive associations of the second trimester maternal mixture of phthalates and bisphenols with DNA methylation in cord blood.ConclusionsAlthough we did not identify genome-wide significant results, we identified some suggestive associations of exposure to a maternal mixture of phthalates and bisphenols in the first and second trimester with DNA methylation in cord blood that need further exploration in larger study samples.

BackgroundIn utero arsenic exposure may alter fetal developmental programming by altering DNA methylation, which may result in a higher risk of disease in later life. We evaluated the association between in utero arsenic exposure and DNA methylation (DNAm) in cord blood and its influence in later life.MethodsGenome-wide DNA methylation in cord blood from 64 subjects in the Taiwanese maternal infant and birth cohort was analyzed. Robust regressions were applied to assess the association of DNA methylation with in utero arsenic exposure. Multiple testing was adjusted by controlling false discovery rate (FDR) of 0.05. The DAVID bioinformatics tool was implemented for functional annotation analyses on the detected CpGs. The identified CpGs were further tested in an independent cohort. For the CpGs replicated in the independent cohort, linear mixed models were applied to assess the association of DNA methylation with low-density lipoprotein (LDL) at different ages (2, 5, 8, 11 and 14 years).ResultsIn total, 579 out of 385,183 CpGs were identified after adjusting for multiple testing (FDR = 0.05), of which ~60% were positively associated with arsenic exposure. Functional annotation analysis on these CpGs detected 17 KEGG pathways (FDR = 0.05) including pathways for cardiovascular diseases (CVD) and diabetes mellitus. In the independent cohort, about 46% (252 out of 553 CpGs) of the identified CpGs showed associations consistent with those in the study cohort. In total, 11 CpGs replicated in the independent cohort were in the pathways related to CVD and diabetes mellitus. Via longitudinal analyses, we found at 5 out of the 11 CpGs methylation was associated with LDL over time and interactions between DNA methylation and time were observed at 4 of the 5 CpGs, cg25189764 (coeff = 0.157, p-value = 0.047), cg04986899 (coeff. For interaction [coeff.int] = 0.030, p-value = 0.024), cg04903360 (coeff.int = 0.026, p-value = 0.032), cg08198265 (coeff.int = −0.063, p-value = 0.0021), cg10473311 (coeff.int = −0.021, p-value = 0.027).ConclusionIn utero arsenic exposure was associated with cord blood DNA methylation at various CpGs. The identified CpGs may help determine pathological epigenetic mechanisms linked to in utero arsenic exposure. Five CpGs (cg25189764, cg04986899, cg04903360, cg08198265 and cg10473311) may serve as epigenetic markers for changes in LDL later in life.

BackgroundPrenatal symptoms of depression (PND) and anxiety affect up to every third pregnancy. Children of mothers with mental health problems are at higher risk of developmental problems, possibly through epigenetic mechanisms together with other factors such as genetic and environmental. We investigated DNA methylation in cord blood in relation to PND, taking into consideration a history of depression, co-morbidity with anxiety and selective serotonin reuptake inhibitors (SSRI) use, and stratified by sex of the child. Mothers (N = 373) prospectively filled out web-based questionnaires regarding mood symptoms and SSRI use throughout pregnancy. Cord blood was collected at birth and DNA methylation was measured using Illumina MethylationEPIC array at 850 000 CpG sites throughout the genome. Differentially methylated regions were identified using Kruskal–Wallis test, and Benjamini-Hochberg adjusted p-values < 0.05 were considered significant.ResultsNo differential DNA methylation was associated with PND alone; however, differential DNA methylation was observed in children exposed to comorbid PND with anxiety symptoms compared with healthy controls in ABCF1 (log twofold change − 0.2), but not after stratification by sex of the child. DNA methylation in children exposed to PND without SSRI treatment and healthy controls both differed in comparison with SSRI exposed children at several sites and regions, among which hypomethylation was observed in CpGs in the promoter region of CRBN (log2 fold change − 0.57), involved in brain development, and hypermethylation in MDFIC (log2 fold change 0.45), associated with the glucocorticoid stress response.ConclusionAlthough it is not possible to assess if these methylation differences are due to SSRI treatment itself or to more severe depression, our findings add on to existing knowledge that there might be different biological consequences for the child depending on whether maternal PND was treated with SSRIs or not.

Intrauterine growth restriction (IUGR) is associated with faltered growth and development later in life. Alteration in DNA methylation may occur among IUGR babies and it can have bearing on the outcome. To compare the DNA methylation in the cord blood among IUGR and appropriate for gestational age (AGA) babies and find it is association with their neurodevelopmental outcome at 18 months of age. Genomic DNA methylation among 40 IUGR and equal number of AGA neonates was estimated by using 5-mC ELISA kit in the cord blood. Infants were assessed at birth and their anthropometric measurements were taken. They were regularly followed up and assessed for neurodevelopment outcome till 18 months of age using DASII (Developmental Assessment Scale for Indian Infants). DNA methylation was correlated with neurodevelopmental outcome. Numbers and percentages were used for categorical data. Mean and SD were used for continuous variables. The significant mean difference between IUGR and AGA was determined by independent Student t-test. To study the association between the DNA methylation and outcome, Spearman correlation was used. A p < 0.05 was considered as statistically significant. Significant difference in DNA methylation was observed between IUGR and AGA infants (IUGR: 3.12 ± 1.24; AGA: 4.40 ± 2.03; p < 0.001). Anthropometry (weight, length and head circumference) at birth was significantly decreased among IUGR infants. Hospital stay was significantly longer for IUGR infants. Motor (IUGR: 89.98 ± 18.77; AGA: 101.75 ± 9.62; p < 0.001), and mental (IUGR: 90.81 ± 11.13; AGA: 105.71 ± 7.20; p < 0.001) scores were significantly decreased among IUGR compared with AGA neonates at 18 months of follow-up. Global DNA methylation had a significant positive correlation with mental score but not with motor developmental score. IUGR babies had lower motor and mental score compared with AGA babies. Cord blood global DNA methylation significantly correlated with mental development score but not with motor development at 18 months of age.

Hypertensive disorders of pregnancy (HDP) are associated with low birth weight, shorter gestational age, and increased risk of maternal and offspring cardiovascular diseases later in life. The mechanisms involved are poorly understood, but epigenetic regulation of gene expression may play a part. We performed meta-analyses in the Pregnancy and Childhood Epigenetics Consortium to test the association between either maternal HDP (10 cohorts; n=5242 [cases=476]) or preeclampsia (3 cohorts; n=2219 [cases=135]) and epigenome-wide DNA methylation in cord blood using the Illumina HumanMethylation450 BeadChip. In models adjusted for confounders, and with Bonferroni correction, HDP and preeclampsia were associated with DNA methylation at 43 and 26 CpG sites, respectively. HDP was associated with higher methylation at 27 (63%) of the 43 sites, and across all 43 sites, the mean absolute difference in methylation was between 0.6% and 2.6%. Epigenome-wide associations of HDP with offspring DNA methylation were modestly consistent with the equivalent epigenome-wide associations of preeclampsia with offspring DNA methylation (R2=0.26). In longitudinal analyses conducted in 1 study (n=108 HDP cases; 550 controls), there were similar changes in DNA methylation in offspring of those with and without HDP up to adolescence. Pathway analysis suggested that genes located at/near HDP-associated sites may be involved in developmental, embryogenesis, or neurological pathways. HDP is associated with offspring DNA methylation with potential relevance to development.

B45 Polycyclic aromatic hydrocarbons (PAHs) are widespread organic carcinogenic pollutants. When metabolized in vivo, PAHs form reactive diol epoxides that bind to DNA at guanine residues forming adducts. PAH exposure has also been associated with alterations in genomic cytosine methylation. Both PAH-DNA adducts and altered DNA methylation have been associated with increased cancer risk. We sought to explore the relationship between prenatal PAH exposure, global DNA methylation and PAH-DNA adducts in a New York City birth cohort. Cord blood was collected from deliveries of non-smoking, African Americans and Dominicans, ages 18-35, residing in N. Manhattan and S. Bronx. Personal air monitors measured PAH during their 8th month of pregnancy. We measured benzo[a]pyrene (B[a]P)-DNA adducts (which serve as a proxy for PAH-DNA adducts) in cord blood using high-performance liquid chromatography-fluorescence. We measured genomic DNA methylation in cord blood leukocytes using the MethylampTM global DNA methylation quantification kit. Demographic and epidemiologic risk factors were collected prospectively, including maternal age, ethnicity, parity, and prenatal tobacco smoke exposure, and child’s gender We found that prenatal PAH exposure was associated global DNA hypomethylation such that average methylation among those in the highest quartile of prenatal PAH exposure was 1.17 ng/100 ng total DNA as compared 1.83 ng/100 ng total DNA in the lowest quartile (p &amp;lt; 0.01). Conversely, those with detectable PAH-DNA adducts had higher levels of DNA methylation (1.43 ng/100 ng total DNA) as compared to those with non-detectable adducts (1.16 ng/100 ng total DNA) (p = 0.02). Using multiple variable linear regression, PAH exposure was independently associated with hypomethylation (average difference in methylation among those in the highest vs. lowest quartile of exposure = -0.42, 95% CI: -0.75, -0.09) and the presence of DNA adducts was associated with hypermethyaltion (average difference in methylation among those with detectable vs. non-detectable adducts = 0.28, 95% CI: 0.05, 0.49). Adjusting for potential confounders did not significantly alter these independent associations, indicating that the lowest level of global DNA methylation was found among those with non-detectable adducts and high PAH exposure, and the highest level of DNA methylation was found among those with detectable adducts and low PAH exposure. While the mechanism by which prenatal PAH exposure results in DNA adducts is well understood, the way exposure may impact methylation is not known. These data suggest that in the presence of DNA adducts, PAH exposure is associated with a reduction in methylation, but when adducts are non-detectable, the same PAH exposure is associated with an even larger methylation reduction. It is possible that the presence of adducts may be partially preventing PAH compounds (or metabolites) from accessing the DNA, leading to less of a change in methylation. It is also possible that the shift in global methylation from PAH exposure may prevent adduct formation. These speculations as well as the associations observed in this analysis require confirmation in other settings/populations. Because methylation changes are potentially reversible, it is possible that if these associations are confirmed, methylation may serve as a target for intervention. Citation Information: Cancer Prev Res 2008;1(7 Suppl):B45.

Background:The global pandemic of coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). About 18.4% of total Covid-19 cases were reported in children. Even though vertical transmission from mother to infant is likely to occur at a low rate, exposure to COVID-19 during fetal life may alter DNA methylation patterns with potential long-term effects.Objective:To determine if COVID-19 infection during pregnancy alters the DNA methylation patterns in umbilical cord blood cells from term infants and to identify potential pathways and genes affected by exposure to COVID-19 infection.Methods:Umbilical cord blood was collected from 8 infants exposed to COVID-19 during pregnancy and 8 control infants with no COVID-19 exposure. Genomic DNA was isolated from umbilical cord blood cells and genome-wide DNA methylation was performed using Illumina Methylation EPIC Array.Results:119 differentially methylated loci were identified at the FDR level of 0.20 (64 hypermethylated loci and 55 hypomethylated loci) in umbilical cord blood cells of COVID-19 exposed neonates compared to the control group. Important canonical pathways identified by Ingenuity Pathway Analysis (IPA) were related to stress response (corticotropin releasing hormone signaling, glucocorticoid receptor signaling, and oxytocin in brain signaling pathway), and cardiovascular disease and development (nitric oxide signaling in the cardiovascular system, apelin cardiomyocyte signaling pathways, factors promoting cardiogenesis, and renin-angiotensin signaling). The genes affected by the differential methylations were associated with cardiac, renal, hepatic, neurological diseases, developmental and immunological disorders.Conclusions:COVID-19 induces differential DNA methylation in umbilical cord blood cells. The differentially methylated genes may contribute to hepatic, renal, cardiac, developmental and immunological disorders in offspring born to mothers with COVID-19 infection during pregnancy, and their developmental regulation.

Prenatal exposure to drinking water disinfection by-products and DNA methylation in cord blood.

ABSTRACTCord blood DNA methylation is associated with numerous health outcomes and environmental exposures. Whole cord blood DNA reflects all nucleated blood cell types, while centrifuging whole blood separates red blood cells, generating a white blood cell buffy coat. Both sample types are used in DNA methylation studies. Cell types have unique methylation patterns and processing can impact cell distributions, which may influence comparability. We evaluated differences in cell composition and DNA methylation between cord blood buffy coat and whole cord blood samples. Cord blood DNA methylation was measured with the Infinium EPIC BeadChip (Illumina) in eight individuals, each contributing buffy coat and whole blood samples. We analyzed principal components (PC) of methylation, performed hierarchical clustering, and computed correlations of mean-centered methylation between pairs. We conducted moderated t-tests on single sites and estimated cell composition. DNA methylation PCs were associated with individual (PPC1 = 1.4 × 10−9; PPC2 = 2.9 × 10−5; PPC3 = 3.8 × 10-5; PPC4 = 4.2 × 10-6; PPC5 = 9.9 × 10-13, PPC6 = 1.3 × 10−11) and not with sample type (PPC1-6>0.7). Samples hierarchically clustered by individual. Pearson correlations of mean-centered methylation between paired samples ranged from r = 0.66 to r = 0.87. No individual site significantly differed between buffy coat and whole cord blood when adjusting for multiple comparisons (five sites had unadjusted P<10−5). Estimated cell type proportions did not differ by sample type (P = 0.46), and estimated proportions were highly correlated between paired samples (r = 0.99). Differences in methylation and cell composition between buffy coat and whole cord blood are much lower than inter-individual variation, demonstrating that both sample preparation types can be analytically combined and compared.