Prenatal Metal Concentrations and Childhood Cardiometabolic Risk Using Bayesian Kernel Machine Regression to Assess Mixture and Interaction Effects.

BACKGROUND: Trace metal concentrations may affect cardiometabolic risk, but the role of prenatal exposure is unclear. We examined (1) the relation between blood metal concentrations during pregnancy and child cardiometabolic risk factors; (2) overall effects of metals mixture (essential vs. nonessential); and (3) interactions between metals. METHODS: We measured 11 metals in maternal second-trimester whole blood in a prospective birth cohort in Mexico City. In children 4-6 years old, we measured body mass index (BMI), percent body fat, and blood pressure (N = 609); and plasma hemoglobin A1C (HbA1c), non-high-density lipoprotein (HDL) cholesterol, triglycerides, leptin, and adiponectin (N = 411). We constructed cardiometabolic component scores using age- and sex-adjusted z scores and averaged five scores to create a global risk score. We estimated linear associations of each metal with individual z scores and used Bayesian Kernel Machine Regression to assess metal mixtures and interactions. RESULTS: Higher total metals were associated with lower HbA1c, leptin, and systolic blood pressure, and with higher adiponectin and non-HDL cholesterol. We observed no interactions between metals. Higher selenium was associated with lower triglycerides in linear (ß = -1.01 z score units per 1 unit ln(Se), 95% CI = -1.84, -0.18) and Bayesian Kernel Machine Regression models. Manganese was associated with decreased HbA1c in linear models (ß = -0.32 and 95% CI = -0.61, -0.03). Antimony and arsenic were associated with lower leptin in Bayesian Kernel Machine Regression models. Essential metals were more strongly associated with cardiometabolic risk than were nonessential metals. CONCLUSIONS: Low essential metals during pregnancy were associated with increased cardiometabolic risk factors in childhood.

Association between prenatal particulate air pollution exposure and telomere length in cord blood: Effect modification by fetal sex.

INTRODUCTION: In utero particulate matter exposure produces oxidative stress that impacts cellular processes that include telomere biology. Newborn telomere length is likely critical to an individual's telomere biology; reduction in this initial telomere setting may signal increased susceptibility to adverse outcomes later in life. We examined associations between prenatal particulate matter with diameter ≤2.5 µm (PM2.5) and relative leukocyte telomere length (LTL) measured in cord blood using a data-driven approach to characterize sensitive windows of prenatal PM2.5 effects and explore sex differences. METHODS: Women who were residents of Mexico City and affiliated with the Mexican Social Security System were recruited during pregnancy (n = 423 for analyses). Mothers' prenatal exposure to PM2.5 was estimated based on residence during pregnancy using a validated satellite-based spatio-temporally resolved prediction model. Leukocyte DNA was extracted from cord blood obtained at delivery. Duplex quantitative polymerase chain reaction was used to compare the relative amplification of the telomere repeat copy number to single gene (albumin) copy number. A distributed lag model incorporating weekly averages for PM2.5 over gestation was used in order to explore sensitive windows. Sex-specific associations were examined using Bayesian distributed lag interaction models. RESULTS: In models that included child's sex, mother's age at delivery, prenatal environmental tobacco smoke exposure, pre-pregnancy BMI, gestational age, birth season and assay batch, we found significant associations between higher PM2.5 exposure during early pregnancy (4-9 weeks) and shorter LTL in cord blood. We also identified two more windows at 14-19 and 34-36 weeks in which increased PM2.5 exposure was associated with longer LTL. In stratified analyses, the mean and cumulative associations between PM2.5 and shortened LTL were stronger in girls when compared to boys. CONCLUSIONS: Increased PM2.5 during specific prenatal windows was associated with shorter LTL and longer LTL. PM2.5 was more strongly associated with shortened LTL in girls when compared to boys. Understanding sex and temporal differences in response to air pollution may provide unique insight into mechanisms.

Prenatal Stress, Methylation in Inflammation-Related Genes, and Adiposity Measures in Early Childhood: the Programming Research in Obesity, Growth Environment and Social Stress Cohort Study.

OBJECTIVE: Maternal stress during pregnancy may influence childhood growth and adiposity, possibly through immune/inflammatory programming. We investigated whether exposure to prenatal stress and methylation in inflammation-related genes were associated with childhood adiposity in 424 mother-child pairs in Mexico City, Mexico. METHODS: A stress index was created based on four prenatally administered stress-related scales (Exposure to Violence, Crisis in Family Systems, State-Trait Anxiety Inventory, and Edinburgh Postnatal Depression Scale). We measured weight, height, body fat mass (BFM), percentage body fat (PBF), and waist circumference in early childhood (age range, 4-6 years). Body mass index (BMI) z scores were calculated according to World Health Organization standards. DNA methylation in gene promoters of tumor necrosis factor α, interleukin 8, and interleukin 6 (IL6) in umbilical cord blood were determined by pyrosequencing. RESULTS: An interquartile range increase in stress index (27.3) was associated with decreases of 0.14 unit in BMI z score (95% confidence interval [CI] = -0.28 to -0.005), 5.6% in BFM (95% CI = -9.7 to -1.4), 3.5% in PBF (95% CI = -6.3 to -0.5), and 1.2% in waist circumference (95% CI = -2.4 to -0.04) in multivariable-adjusted models. An interquartile range increase in IL6 methylation (3.9%) was associated with increases of 0.23 unit in BMI z score (95% CI = 0.06-0.40), 8.1% (95% CI = 2.3-14.3) in BFM, 5.5% (95% CI = 1.7-9.5) in PBF, and 1.7% (95% CI = 0.2-3.3) in waist circumference. CONCLUSIONS: Prenatal stress was associated with decreased childhood adiposity, whereas cord blood IL6 methylation was associated with increased childhood adiposity in Mexican children.

Prenatal fine particulate exposure associated with reduced childhood lung function and nasal epithelia GSTP1 hypermethylation: Sex-specific effects.

BACKGROUND: In utero exposure to particulate matter with an aerodynamic diameter of less than 2.5 µm (PM2.5) has been linked to child lung function. Overlapping evidence suggests that child sex and exposure timing may modify effects and associations may be mediated through glutathione S-transferase P1 (GSTP1) methylation. METHODS: We prospectively examined associations among prenatal PM2.5 exposure and child lung function and GSTP1 methylation in an urban pregnancy cohort study. We employed a validated satellite-based spatiotemporally resolved prediction model to estimate daily prenatal PM2.5 exposure over gestation. We used Baysian distributed lag interaction models (BDLIMs) to identify sensitive windows for prenatal PM2.5 exposure on child lung function and nasal epithelia GSTP1 methylation at age 7 years, and to examine effect modification by child sex. RESULTS: BDLIMs identified a sensitive window for prenatal PM2.5 exposure at 35-40 weeks gestation [cumulative effect estimate (CEE) = - 0.10, 95%CI = - 0.19 to - 0.01, per µg/m3 increase in PM2.5] and at 36-40 weeks (CEE = - 0.12, 95%CI = - 0.20 to - 0.01) on FEV1 and FVC, respectively, in boys. BDLIMs also identified a sensitive window of exposure at 37-40 weeks gestation between higher prenatal PM2.5 exposure and increased GSTP1 percent methylation. The association between higher GSTP1 percent methylation and decreased FEV1 was borderline significant in the sample as a whole (ß = - 0.37, SE = 0.20, p = 0.06) and in boys in stratified analyses (ß = - 0.56, SE = 0.29, p = 0.05). CONCLUSIONS: Prenatal PM2.5 exposure in late pregnancy was associated with impaired early childhood lung function and hypermethylation of GSTPI in DNA isolated from nasal epithelial cells. There was a trend towards higher GSTP1 percent methylation being associated with reduced FEV1. All findings were most evident among boys.

Traffic-Related Air Pollution, Blood Pressure, and Adaptive Response of Mitochondrial Abundance.

BACKGROUND: Exposure to black carbon (BC), a tracer of vehicular-traffic pollution, is associated with increased blood pressure (BP). Identifying biological factors that attenuate BC effects on BP can inform prevention. We evaluated the role of mitochondrial abundance, an adaptive mechanism compensating for cellular-redox imbalance, in the BC-BP relationship. METHODS AND RESULTS: At ≥ 1 visits among 675 older men from the Normative Aging Study (observations=1252), we assessed daily BP and ambient BC levels from a stationary monitor. To determine blood mitochondrial abundance, we used whole blood to analyze mitochondrial-to-nuclear DNA ratio (mtDNA/nDNA) using quantitative polymerase chain reaction. Every standard deviation increase in the 28-day BC moving average was associated with 1.97 mm Hg (95% confidence interval [CI], 1.23-2.72; P<0.0001) and 3.46 mm Hg (95% CI, 2.06-4.87; P<0.0001) higher diastolic and systolic BP, respectively. Positive BC-BP associations existed throughout all time windows. BC moving averages (5-day to 28-day) were associated with increased mtDNA/nDNA; every standard deviation increase in 28-day BC moving average was associated with 0.12 standard deviation (95% CI, 0.03-0.20; P=0.007) higher mtDNA/nDNA. High mtDNA/nDNA significantly attenuated the BC-systolic BP association throughout all time windows. The estimated effect of 28-day BC moving average on systolic BP was 1.95-fold larger for individuals at the lowest mtDNA/nDNA quartile midpoint (4.68 mm Hg; 95% CI, 3.03-6.33; P<0.0001), in comparison with the top quartile midpoint (2.40 mm Hg; 95% CI, 0.81-3.99; P=0.003). CONCLUSIONS: In older adults, short-term to moderate-term ambient BC levels were associated with increased BP and blood mitochondrial abundance. Our findings indicate that increased blood mitochondrial abundance is a compensatory response and attenuates the cardiac effects of BC.

In Utero Exposure to Caffeine and Acetaminophen, the Gut Microbiome, and Neurodevelopmental Outcomes: A Prospective Birth Cohort Study.

Pregnant individuals are exposed to acetaminophen and caffeine, but it is unknown how these exposures interact with the developing gut microbiome. We aimed to determine whether acetaminophen and/or caffeine relate to the childhood gut microbiome and whether features of the gut microbiome alter the relationship between acetaminophen/caffeine and neurodevelopment. Forty-nine and 85 participants provided meconium and stool samples at 6-7, respectively, for exposure and microbiome assessment. Fecal acetaminophen and caffeine concentrations were quantified, and fecal DNA underwent metagenomic sequencing. Caregivers and study staff assessed the participants' motor and cognitive development using standardized scales. Prenatal exposures had stronger associations with the childhood microbiome than concurrent exposures. Prenatal acetaminophen exposure was associated with a trend of lower gut bacterial diversity in childhood [ß = -0.17 Shannon Index, 95% CI: (-0.31, -0.04)] and was marginally associated with differences in the relative abundances of features of the gut microbiome at the phylum (Firmicutes, Actinobacteria) and gene pathway levels. Among the participants with a higher relative abundance of Proteobacteria, prenatal exposure to acetaminophen and caffeine was associated with lower scores on WISC-IV subscales. Acetaminophen during bacterial colonization of the naïve gut is associated with lasting alterations in childhood microbiome composition. Future studies may inform our understanding of downstream health effects.

Battle of epigenetic proportions: comparing Illumina's EPIC methylation microarrays and TruSeq targeted bisulfite sequencing.

DNA methylation microarrays have been the platform of choice for epigenome-wide association studies in epidemiology, but declining costs have rendered targeted bisulphite sequencing a feasible alternative. Nonetheless, the literature for researchers seeking guidance on which platform to choose is sparse. To fill this gap, we conducted a comparison study in which we processed cord blood samples from four newborns in duplicates using both the Illumina HumanMethylationEPIC BeadChip and the Illumina TruSeq Methyl Capture EPIC Kit, and evaluated both platforms in regard to coverage, reproducibility, and identification of differential methylation. We conclude that with current analytic goals microarrays still outperform bisulphite sequencing for precise quantification of DNA methylation.

Age and mitochondrial DNA copy number influence the association between outdoor temperature and cognitive function: Insights from the VA Normative Aging Study.

BACKGROUND: General cognitive function deteriorates with aging, a change that has been linked to outdoor temperature. Older individuals have reduced ability to adapt to changes in outdoor temperature than younger people. However, to what extent short-term changes in outdoor temperature interact with mitochondria to affect cognition in older people has not yet been determined. METHODS: Our study included 591 participants of the Normative Aging Study who underwent multiple examinations between 2000 and 2013. Cognitive function was evaluated via the Mini-Mental State Examination. Outdoor temperature was estimated at residential addresses 1 day before the examination using on a validated spatiotemporal temperature model. Mitochondrial DNA copy number (mtDNAcn) was determined using buffy coat samples. RESULTS: We found an interaction between temperature, age, mtDNAcn, and cognition. In individuals 84 years of age or older, cooler temperature was associated with low cognition (odds ratio = 1.2; 95% confidence interval = 1.05, 1.35 for a 1°C decrease in temperature; P = 0.007). We found higher odds ratio per 1°C decrease in temperature among individuals with lower mtDNAcn (ß3 = 0.12; 95% confidence interval = 0.01, 0.22; P interaction = 0.02). CONCLUSIONS: Our findings, albeit potentially underpowered, suggest that older individuals may be more susceptible to the influence of short-term temperature exposure on cognition. Moreover, the level of mtDNAcn may also modify the association between temperature and cognitive function, indicating a possible role of these cellular elements in this relationship.

Prenatal manganese and cord blood mitochondrial DNA copy number: Effect modification by maternal anemic status.

INTRODUCTION: Manganese (Mn) is an essential nutrient but also a toxicant at high exposures, when it can induce oxidative stress (OS). Mn uptake is inversely correlated with iron status, therefore anemic individuals may be more susceptible to Mn overload induced-OS, which can manifest as changes in mitochondrial DNA copy number (mtDNA CN). Our objectives were to: 1) determine stage-specific associations of prenatal Mn exposure with cord blood MtDNA CN; and 2) investigate effect modification by maternal anemia, ferritin, and mean corpuscular volume (MCV). MATERIALS AND METHODS: We measured whole blood Mn, hemoglobin, serum ferritin, and MCV in the 2nd and 3rd trimester, in maternal blood at birth, and in cord blood from a prospective birth cohort in Mexico City, Mexico (n = 485). We then extracted DNA from cord blood leukocytes to determine mtDNA CN. We used robust regression to measure associations between Mn and mtDNA CN at each trimester and at birth. Anemia (hemoglobin ≤11 g/dL), iron deficiency (ferritin ≤15 ng/mL) and MCV (stratified at median), were examined as effect modifiers. RESULTS: Mn levels increased throughout pregnancy, and Mn was inversely correlated with ferritin. We observed a positive association between Mn in the 3rd trimester and Mn in cord blood and mtDNA CN (ß = 0.04-0.05; 95% CI = 0.01, 0.08). Anemia significantly modified the association between mtDNA CN and Mn in the 2nd trimester. We found a positive association between 2nd trimester Mn and mtDNA CN in mothers with normal hemoglobin, and a negative association in those with low hemoglobin. (ßhigh = 0.06; 95% CI = 0.01, 0.11; p = 0.01 and ßlow = -0.06; 95% CI = 0.03, -0.13; p = 0.06). No associations were detected between anemia, iron deficiency and MCV and mtDNA CN. CONCLUSIONS: Maternal blood Mn in the 3rd trimester and in cord blood was positively associated with mtDNA CN, suggesting that higher late pregnancy prenatal Mn exposures can impact newborn mitochondria by promoting OS. Furthermore, 2nd trimester Mn was positively associated with mtDNA in non-anemic mother-child pairs but inversely associated in anemic individuals, indicating potential interactions between Mn and chronic anemia.

Associations of prenatal exposure to polybrominated diphenyl ethers and polychlorinated biphenyls with long-term gut microbiome structure: a pilot study.

BACKGROUND: The gut microbiome is influenced by early-life exposures, but-despite potentially enormous implications for child health-is understudied in environmental epidemiology. This pilot study is one of the first to explore in utero exposures and long-term gut microbiome profiles. We examined the association between exposure to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) during pregnancy and the mid-childhood gut microbiome. METHODS: We measured levels of PBDE-47, -99, -100, and -153 and PCB-138, -153, and -180 in maternal plasma during early pregnancy (n=18) and at delivery (n=25) in women of European descent who breastfed the child participant of the Gestation and Environment cohort in Sherbrooke, Québec (recruited 2007-2009). Bacteria in the mid-childhood (6-8 years) fecal microbiome were detected with 16S rRNA sequencing. To test for differences at the taxon level, we used the Microbiome Comprehensive Association Mapping algorithm. RESULTS: Early pregnancy PCB-153, -180, and the sum of PCBs (Σ3PCB) concentrations were associated with a higher relative abundance of Propionibacteriales and Propionibacteriaceae in mid-childhood. Higher PCB-180 and Σ3PCB were associated with higher relative abundance of Bacillales Family XI. Higher PBDE-99 exposure was associated with a decrease in uncultured bacteria within the Ruminococcaceae NK4A214 group and PBDE-47 was associated with differences in Ruminococcus 2. These taxon-level changes did not result in differences in within- or between-subject diversity. Exposures at delivery were not associated with differences in taxa. CONCLUSIONS: Prenatal exposure to PCBs and PBDEs is associated with mid-childhood gut microbiome profiles. Larger studies are needed to confirm these results and explore health implications.

Association Between Meconium Acetaminophen and Childhood Neurocognitive Development in GESTE, a Canadian Cohort Study.

Acetaminophen is the only over-the-counter pain reliever that is not contraindicated during pregnancy, but recent studies have questioned whether acetaminophen is safe for the fetus, particularly the developing brain. This prospective birth cohort study probed the previously observed association between in utero exposure to acetaminophen and neurodevelopment by using concentrations of acetaminophen measured in meconium, which more objectively captures exposure of the fetus than maternal report. Exposure, measured by liquid chromatography coupled with tandem mass spectrometry, was categorized into nondetection, low detection, and high detection levels. At age 6-8 years, children completed a set of subtests from the Wechsler Intelligence Scale for Children, 4th edition. Additionally, this study examined potential effect modification by child sex on the association between acetaminophen exposure and neurodevelopment. In fully adjusted models, in utero exposure to acetaminophen was not statistically significantly associated with decreased scores on any of the examined subtests in all children combined (n = 118). The effect of in utero acetaminophen exposure on the Coding subtest was marginally significantly different among boys and girls, with girls performing significantly better on the task with higher levels of acetaminophen compared with girls with undetectable levels of exposure (ßgirls, low = 2.83 [0.97, 4.70], ßgirls, high = 1.95 [-0.03, 3.93], ßboys, low = .02 [-1.78, 1.81], ßboys, high = -.39 [-2.09, 1.31], pinteraction = .06). Effect modification by child sex was not observed on other subtests. These results do not support prior reports of adverse neurodevelopmental effects of in utero exposure to acetaminophen.

The nasal methylome as a biomarker of asthma and airway inflammation in children.

The nasal cellular epigenome may serve as biomarker of airway disease and environmental response. Here we collect nasal swabs from the anterior nares of 547 children (mean-age 12.9 y), and measure DNA methylation (DNAm) with the Infinium MethylationEPIC BeadChip. We perform nasal Epigenome-Wide Association analyses (EWAS) of current asthma, allergen sensitization, allergic rhinitis, fractional exhaled nitric oxide (FeNO) and lung function. We find multiple differentially methylated CpGs (FDR < 0.05) and Regions (DMRs; ≥ 5-CpGs and FDR < 0.05) for asthma (285-CpGs), FeNO (8,372-CpGs; 191-DMRs), total IgE (3-CpGs; 3-DMRs), environment IgE (17-CpGs; 4-DMRs), allergic asthma (1,235-CpGs; 7-DMRs) and bronchodilator response (130-CpGs). Discovered DMRs annotated to genes implicated in allergic asthma, Th2 activation and eosinophilia (EPX, IL4, IL13) and genes previously associated with asthma and IgE in EWAS of blood (ACOT7, SLC25A25). Asthma, IgE and FeNO were associated with nasal epigenetic age acceleration. The nasal epigenome is a sensitive biomarker of asthma, allergy and airway inflammation.

Altered cord blood mitochondrial DNA content and pregnancy lead exposure in the PROGRESS cohort.

INTRODUCTION: Lead (Pb) crosses the placenta and can cause oxidative stress, reduced fetal growth and neurological problems. The principal source of oxidative stress in human cells is mitochondria. Therefore, disruption of normal mitochondrial function during pregnancy may represent a primary mechanism behind the adverse effects of lead. We sought to assess the association of Pb exposure during pregnancy with mitochondrial DNA (mtDNA) content, a sensitive marker of mitochondrial function, in cord blood. MATERIALS AND METHODS: This study comprised mother-infant pairs from the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) study, a prospective birth-cohort that enrolled 1050 pregnant women from Mexico City who were receiving prenatal care between December 2007 and July 2011. Quantitative PCR was used to calculate relative MtDNA content (mitochondrial-to-nuclear DNA ratio (mtDNA/nDNA)) in cord blood. Lead concentrations in both maternal blood (2nd and 3rd trimester and at delivery day) and in cord blood were measured by ICP-MS. Multivariable regression models adjusting for multiple confounders were fitted with 410 mother-infant pairs for whom complete data for mtDNA content, lead levels, and covariates were available. RESULTS: Maternal blood Pb measured in the second (mean 3.79 µg/dL, SD 2.63; ß = 0.059, 95% CI 0.008, 0.111) and third trimester (mean 3.90 µg/dL; SD 2.84; ß = 0.054, 95% CI 0.002, 0.107) during pregnancy and PB in cord blood (mean 3.50 µg/dL, SD 2.59; ß = 0.050, 95% CI 0.004; 0.096) were associated with increased cord blood mtDNA content (mean 1.46, SD 0.44). In two-way interaction analyses, cord blood Pb marginally interacted with gestational age leading to an increase in mtDNA content for pre-term births (Benjamini-Hochberg False Discovery Rate correction; BH-FDR = 0.08). CONCLUSION: This study shows that lead exposure in pregnancy alters mtDNA content in cord blood; therefore, alteration of mtDNA content might be a mechanism underlying the toxicity of lead.

Methylome-wide association study provides evidence of particulate matter air pollution-associated DNA methylation.

BACKGROUND: DNA methylation (DNAm) may contribute to processes that underlie associations between air pollution and poor health. Therefore, our objective was to evaluate associations between DNAm and ambient concentrations of particulate matter (PM) ≤2.5, ≤10, and 2.5-10 µm in diameter (PM2.5; PM10; PM2.5-10). METHODS: We conducted a methylome-wide association study among twelve cohort- and race/ethnicity-stratified subpopulations from the Women's Health Initiative and the Atherosclerosis Risk in Communities study (n = 8397; mean age: 61.5 years; 83% female; 45% African American; 9% Hispanic/Latino American). We averaged geocoded address-specific estimates of daily and monthly mean PM concentrations over 2, 7, 28, and 365 days and 1 and 12 months before exams at which we measured leukocyte DNAm in whole blood. We estimated subpopulation-specific, DNAm-PM associations at approximately 485,000 Cytosine-phosphate-Guanine (CpG) sites in multi-level, linear, mixed-effects models. We combined subpopulation- and site-specific estimates in fixed-effects, inverse variance-weighted meta-analyses, then for associations that exceeded methylome-wide significance and were not heterogeneous across subpopulations (P < 1.0 × 10-7; PCochran's Q > 0.10), we characterized associations using publicly accessible genomic databases and attempted replication in the Cooperative Health Research in the Region of Augsburg (KORA) study. RESULTS: Analyses identified significant DNAm-PM associations at three CpG sites. Twenty-eight-day mean PM10 was positively associated with DNAm at cg19004594 (chromosome 20; MATN4; P = 3.33 × 10-8). One-month mean PM10 and PM2.5-10 were positively associated with DNAm at cg24102420 (chromosome 10; ARPP21; P = 5.84 × 10-8) and inversely associated with DNAm at cg12124767 (chromosome 7; CFTR; P = 9.86 × 10-8). The PM-sensitive CpG sites mapped to neurological, pulmonary, endocrine, and cardiovascular disease-related genes, but DNAm at those sites was not associated with gene expression in blood cells and did not replicate in KORA. CONCLUSIONS: Ambient PM concentrations were associated with DNAm at genomic regions potentially related to poor health among racially, ethnically and environmentally diverse populations of U.S. women and men. Further investigation is warranted to uncover mechanisms through which PM-induced epigenomic changes may cause disease.

Prenatal particulate matter exposure and mitochondrial dysfunction at the maternal-fetal interface: Effect modification by maternal lifetime trauma and child sex.

BACKGROUND: Prenatal ambient fine particulate matter (PM2.5) and maternal chronic psychosocial stress have independently been linked to changes in mithochondrial DNA copy number (mtDNAcn), a marker of mitochondrial response and dysfunction. Further, overlapping research shows sex-specific effects of PM2.5 and stress on developmental outcomes. Interactions among PM2.5, maternal stress, and child sex have not been examined in this context. METHODS: We examined associations among exposure to prenatal PM2.5, maternal lifetime traumatic stressors, and mtDNAcn at birth in a sociodemographically diverse pregnancy cohort (N=167). Mothers' daily exposure to PM2.5 over gestation was estimated using a satellite-based spatio-temporally resolved prediction model. Lifetime exposure to traumatic stressors was ascertained using the Life Stressor Checklist-Revised; exposure was categorized as high vs. low based on a median split. Quantitative real-time polymerase chain reaction (qPCR) was used to determine mtDNAcn in placenta and cord blood leukocytes. Bayesian Distributed Lag Interaction regression models (BDLIMs) were used to statistically model and visualize the PM2.5 timing-dependent pattern of associations with mtDNAcn and explore effect modification by maternal lifetime trauma and child sex. RESULTS: Increased PM2.5 exposure across pregnancy was associated with decreased mtDNAcn in cord blood (cumulative effect estimate=-0.78; 95%CI -1.41, -0.16). Higher maternal lifetime trauma was associated with reduced mtDNAcn in placenta (ß=-0.33; 95%CI -0.63, -0.02). Among women reporting low trauma, increased PM2.5 exposure late in pregnancy (30-38weeks gestation) was significantly associated with decreased mtDNAcn in placenta; no significant association was found in the high trauma group. BDLIMs identified a significant 3-way interaction between PM2.5, maternal trauma, and child sex. Specifically, PM2.5 exposure between 25 and 40weeks gestation was significantly associated with increased placental mtDNAcn among boys of mothers reporting high trauma. In contrast, PM2.5 exposure in this same window was significantly associated with decreased placental mtDNAcn among girls of mothers reporting low trauma. Similar 3-way interactive effects were observed in cord blood. CONCLUSIONS: These results indicate that joint exposure to PM2.5 in late pregnancy and maternal lifetime trauma influence mtDNAcn at the maternal-fetal interface in a sex-specific manner. Additional studies will assist in understanding if the sex-specific patterns reflect distinct pathophysiological processes in addition to mitochondrial dysfunction.

Long noncoding RNA expression in the cervix mid-pregnancy is associated with the length of gestation at delivery.

Infants born preterm are at increased risk of multiple morbidities and mortality. Why some women deliver preterm remains poorly understood. Prior studies have shown that cervical microRNA expression and DNA methylation are associated with the length of gestation. However, no study has examined the role of long noncoding RNAs (lncRNAs) in the cervix during pregnancy. To determine whether expression of lncRNAs is associated with length of gestation at delivery, we analyzed RNA from cervical swabs obtained from 78 women during pregnancy (mean 15.5, SD 5.0, weeks of gestation) who were participating in the Spontaneous Prematurity and Epigenetics of the Cervix (SPEC) Study in Boston, MA, USA. We used a PCR-based platform and found that 9 lncRNAs were expressed in at least 50% of the participants. Of these, a doubling of the expression of TUG1, TINCR, and FALEC was associated with shorter lengths of gestation at delivery [2.8 (95% CI: 0.31, 5.2); 3.3 (0.22, 6.3); and 4.5 (7.3, 1.6) days shorter respectively]. Of the lncRNAs analyzed, none was statistically associated with preterm birth, but expression of FALEC was 2.6-fold higher in women who delivered preterm vs. term (P = 0.051). These findings demonstrate that lncRNAs can be measured in cervical samples obtained during pregnancy and are associated with subsequent length of gestation at delivery. Further, this study supports future work to replicate these findings in other cohorts and perform mechanistic studies to determine the role of lncRNAs in the cervix during pregnancy.

Prenatal Exposure to Mercury: Associations with Global DNA Methylation and Hydroxymethylation in Cord Blood and in Childhood.

BACKGROUND: Mercury is a global pollutant, and prenatal exposure is associated with adverse health effects. To date, no studies have evaluated the association between prenatal mercury exposure and DNA hydroxymethylation, an epigenetic modification important for tissue differentiation and embryonic development. OBJECTIVES: We sought to evaluate the association between prenatal mercury exposure and offspring global DNA methylation and hydroxymethylation at birth and test for persistence of the association in childhood. METHODS: Within Project Viva, a U.S. prebirth cohort, we examined associations of maternal second trimester red blood cell mercury (RBC-Hg) concentrations with global 5-hydroxymethylcytosine (%-5hmC) and 5-methylcytosine (%-5mC) DNA content in blood collected at birth (n=306), early childhood (n=68; 2.9 to 4.9 y), and midchildhood (n=260; 6.7 to 10.5 y). RESULTS: Median prenatal RBC-Hg concentration was 3.23µg/g [interquartile range (IQR)=3.29]. At birth, median cord blood %-5mC, %-5hmC, and their ratio were 4.95%, 0.22%, and 24.37, respectively. The mean adjusted difference [95% confidence interval (CI)] of blood %-5hmC for a doubling in prenatal RBC-Hg concentration was -0.013% (-0.029, 0.002), -0.031% (-0.056, -0.006), and 0.005% (-0.007, 0.018) at birth, early, and midchildhood, respectively. The corresponding relative adjusted change in the genomic ratio of %-5mC to %-5hmC for a doubling in prenatal RBC-Hg concentration was 4.70% (0.04, 9.58), 22.42% (7.73, 39.11), and 0.73% (-4.18, 5.88) at birth, early, and midchildhood, respectively. No associations were present between prenatal maternal RBC-Hg and %-5mC at any time point. CONCLUSIONS: Prenatal mercury exposure was associated with lower %-5hmC genomic content and a corresponding increase in the ratio of %-5mC to %-5hmC in cord blood. This association was persistent in early but not midchildhood blood. Our results demonstrate the potential malleability of epigenetic modifications associated with mercury exposure in utero. https://doi.org/10.1289/EHP1467.

Identifying sensitive windows for prenatal particulate air pollution exposure and mitochondrial DNA content in cord blood.

INTRODUCTION: Changes in mitochondrial DNA (mtDNA) can serve as a marker of cumulative oxidative stress (OS) due to the mitochondria's unique genome and relative lack of repair systems. In utero particulate matter ≤2.5µm (PM2.5) exposure can enhance oxidative stress. Our objective was to identify sensitive windows to predict mtDNA damage experienced in the prenatal period due to PM2.5 exposure using mtDNA content measured in cord blood. MATERIAL AND METHODS: Women affiliated with the Mexican social security system were recruited during pregnancy in the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) study. Mothers with cord blood collected at delivery and complete covariate data were included (n=456). Mothers' prenatal daily exposure to PM2.5 was estimated using a satellite-based spatio-temporally resolved prediction model and place of residence during pregnancy. DNA was extracted from umbilical cord leukocytes. Quantitative real-time polymerase chain reaction (qPCR) was used to determine mtDNA content. A distributive lag regression model (DLM) incorporating weekly averages of daily PM2.5 predictions was constructed to plot the association between exposure and OS over the length of pregnancy. RESULTS: In models that included child's sex, mother's age at delivery, prenatal environmental tobacco smoke exposure, birth year, maternal education, and assay batch, we found significant associations between higher PM2.5 exposure during late pregnancy (35-40weeks) and lower mtDNA content in cord blood. CONCLUSIONS: Increased PM2.5 during a specific prenatal window in the third trimester was associated with decreased mtDNA content suggesting heightened sensitivity to PM-induced OS during this life stage.

The School Inner-City Asthma Intervention Study: Design, rationale, methods, and lessons learned.

Asthma is the most common chronic disease of childhood in the United States, causes significant morbidity, particularly in the inner-city, and accounts for billions of dollars in health care utilization. Home environments are established sources of exposure that exacerbate symptoms and home-based interventions are effective. However, elementary school children spend 7 to 12h a day in school, primarily in one classroom. From the observational School Inner-City Asthma Study we learned that student classroom-specific exposures are associated with worsening asthma symptoms and decline in lung function. We now embark on a randomized, blinded, sham-controlled school environmental intervention trial, built on our extensively established school/community partnerships, to determine the efficacy of a school-based intervention to improve asthma control. This factorial school/classroom based environmental intervention will plan to enroll 300 students with asthma from multiple classrooms in 40 northeastern inner-city elementary schools. Schools will be randomized to receive either integrated pest management versus control and classrooms within these schools to receive either air purifiers or sham control. The primary outcome is asthma symptoms during the school year. This study is an unprecedented opportunity to test whether a community of children can benefit from school or classroom environmental interventions. If effective, this will have great impact as an efficient, cost-effective intervention for inner city children with asthma and may have broad public policy implications.

Detection of long non-coding RNAs in human breastmilk extracellular vesicles: Implications for early child development.

Breastmilk has many documented beneficial effects on the developing human infant, but the components of breastmilk that influence these developmental pathways have not been fully elucidated. Increasing evidence suggests that non-coding RNAs encapsulated in extracellular vesicles (EVs) represent an important mechanism of communication between the mother and child. Long non-coding RNAs (lncRNAs) are of particular interest given their key role in gene expression and development. However, it is not known whether breastmilk EVs contain lncRNAs. We used qRT-PCR to determine whether EVs isolated from human breastmilk contain lncRNAs previously reported to be important for developmental processes. We detected 55 of the 87 screened lncRNAs in EVs from the 30 analyzed breastmilk samples, and CRNDE, DANCR, GAS5, SRA1 and ZFAS1 were detected in >90% of the samples. GAS5, SNHG8 and ZFAS1 levels were highly correlated (Spearman's rho > 0.9; P < 0.0001), which may indicate that the loading of these lncRNAs into breastmilk EVs is regulated by the same pathways. The detected lncRNAs are important epigenetic regulators involved in processes such as immune cell regulation and metabolism. They may target a repertoire of recipient cells in offspring and could be essential for child development and health. Further experimental and epidemiological studies are warranted to determine the impact of breastmilk EV-encapsulated lnRNAs in mother to child signaling.