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Placental mitochondrial methylation and exposure to airborne particulate matter in the early life environment: An ENVIRONAGE birth cohort study.

ABSTRACT: Most research to date has focused on epigenetic modifications in the nuclear genome, with little attention devoted to mitochondrial DNA (mtDNA). Placental mtDNA content has been shown to respond to environmental exposures that induce oxidative stress, including airborne particulate matter (PM). Damaged or non-functioning mitochondria are specifically degraded through mitophagy, exemplified by lower mtDNA content, and could be primed by epigenetic modifications in the mtDNA. We studied placental mtDNA methylation in the context of the early life exposome. We investigated placental tissue from 381 mother-newborn pairs that were enrolled in the ENVIRONAGE birth cohort. We determined mtDNA methylation by bisulfite-pyrosequencing in 2 regions, i.e., the D-loop control region and 12S rRNA (MT-RNR1), and measured mtDNA content by qPCR. PM2.5 exposure was calculated for each participant's home address using a dispersion model. An interquartile range (IQR) increment in PM2.5 exposure over the entire pregnancy was positively associated with mtDNA methylation (MT-RNR1: +0.91%, P = 0.01 and D-loop: +0.21%, P = 0.05) and inversely associated with mtDNA content (relative change of -15.60%, P = 0.001) in placental tissue. mtDNA methylation was estimated to mediate 54% [P = 0.01 (MT-RNR1)] and 27% [P = 0.06 (D-loop)] of the inverse association between PM2.5 exposure and mtDNA content. This study provides new insight into the mechanisms of altered mitochondrial function in the early life environment. Epigenetic modifications in the mitochondrial genome, especially in the MT-RNR1 region, substantially mediate the association between PM2.5 exposure during gestation and placental mtDNA content, which could reflect signs of mitophagy and mitochondrial death.

SUBMITTER: Janssen BG

PROVIDER: S-EPMC4623402 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Placental mitochondrial methylation and exposure to airborne particulate matter in the early life environment: An ENVIRONAGE birth cohort study.

Janssen Bram G BG Byun Hyang-Min HM Gyselaers Wilfried W Lefebvre Wouter W Baccarelli Andrea A AA Nawrot Tim S TS

Epigenetics 20150101 6

Most research to date has focused on epigenetic modifications in the nuclear genome, with little attention devoted to mitochondrial DNA (mtDNA). Placental mtDNA content has been shown to respond to environmental exposures that induce oxidative stress, including airborne particulate matter (PM). Damaged or non-functioning mitochondria are specifically degraded through mitophagy, exemplified by lower mtDNA content, and could be primed by epigenetic modifications in the mtDNA. We studied placental ...[more]

PMID: 25996590

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Project description:BackgroundParticulate matter with a diameter ≤ 2.5 μm (PM2.5) affects human fetal development during pregnancy. Oxidative stress is a putative mechanism by which PM2.5 may exert its effects. Leptin (LEP) is an energy-regulating hormone involved in fetal growth and development.ObjectivesWe investigated in placental tissue whether DNA methylation of the LEP promoter is associated with PM2.5 and whether the oxidative/nitrosative stress biomarker 3-nitrotyrosine (3-NTp) is involved.MethodsLEP DNA methylation status of 361 placentas from the ENVIRONAGE birth cohort was assessed using bisulfite-PCR-pyrosequencing. Placental 3-NTp (n = 313) was determined with an ELISA assay. Daily PM2.5 exposure levels were estimated for each mother's residence, accounting for residential mobility during pregnancy, using a spatiotemporal interpolation model.ResultsAfter adjustment for a priori chosen covariates, placental LEP methylation was 1.4% lower (95% CI: -2.7, -0.19%) in association with an interquartile range increment (7.5 μg/m3) in second-trimester PM2.5 exposure and 0.43% lower (95% CI: -0.85, -0.02%) in association with a doubling of placental 3-NTp content.ConclusionsLEP methylation status in the placenta was negatively associated with PM2.5 exposure during the second trimester, and with placental 3-NTp, a marker of oxidative/nitrosative stress. Additional research is needed to confirm our findings and to assess whether oxidative/nitrosative stress might contribute to associations between PM2.5 and placental epigenetic events. Potential consequences for health during the neonatal period and later in life warrant further exploration. Citation: Saenen ND, Vrijens K, Janssen BG, Roels HA, Neven KY, Vanden Berghe W, Gyselaers W, Vanpoucke C, Lefebvre W, De Boever P, Nawrot TS. 2017. Lower placental leptin promoter methylation in association with fine particulate matter air pollution during pregnancy and placental nitrosative stress at birth in the ENVIRONAGE cohort. Environ Health Perspect 125:262-268; http://dx.doi.org/10.1289/EHP38.

Project description:BackgroundWhile strong evidence supports adverse maternal and offspring consequences of air pollution, mechanisms that involve the placenta, a key part of the intrauterine environment, are largely unknown. Previous studies of air pollution and placental gene expression were small candidate gene studies that rarely considered prenatal windows of exposure or the potential role of offspring sex. We examined overall and sex-specific associations of prenatal exposure to fine particulate matter (PM2.5) with genome-wide placental gene expression.MethodsParticipants with placenta samples, collected at birth, and childhood health outcomes from CANDLE (Memphis, TN) (n = 776) and GAPPS (Seattle, WA) (n = 205) cohorts of the ECHO-PATHWAYS Consortium were included in this study. PM2.5 exposures during trimesters 1, 2, 3, and the first and last months of pregnancy, were estimated using a spatiotemporal model. Cohort-specific linear adjusted models were fit for each exposure window and expression of >11,000 protein coding genes from paired end RNA sequencing data. Models with interaction terms were used to examine PM2.5-offspring sex interactions. False discovery rate (FDR < 0.10) was used to correct for multiple testing.ResultsMean PM2.5 estimate was 10.5-10.7 μg/m3 for CANDLE and 6.0-6.3 μg/m3 for GAPPS participants. In CANDLE, expression of 13 (11 upregulated and 2 downregulated), 20 (11 upregulated and 9 downregulated) and 3 (2 upregulated and 1 downregulated) genes was associated with PM2.5 in the first trimester, second trimester, and first month, respectively. While we did not find any statistically significant association, overall, between PM2.5 and gene expression in GAPPS, we found offspring sex and first month PM2.5 interaction for DDHD1 expression (positive association among males and inverse association among females). We did not observe PM2.5 and offspring sex interactions in CANDLE.ConclusionIn CANDLE, but not GAPPS, we found that prenatal PM2.5 exposure during the first half of pregnancy is associated with placental gene expression.

Project description:Importance:Airborne particulate matter pollution has been associated with preterm birth (PTB) in some studies. However, most of these studies assessed only populations living near monitoring stations, and the association of airborne particulate matter having a median diameter of 1 μm or less (PM1) with PTB has not been studied. Objective:To evaluate whether PM1 concentrations are associated with the risk of PTB. Design, Setting, and Participants:This national cohort study used National Free Preconception Health Examination Project data collected in 324 of 344 prefecture-level cities from 30 provinces of mainland China. In total, 1 300 342 healthy singleton pregnancies were included from women who were in labor from December 1, 2013, through November 30, 2014. Data analysis was conducted between December 1, 2016, and April 1, 2017. Exposures:Predicted weekly PM1 concentration data collected using satellite remote sensing, meteorologic, and land use information matched with the home addresses of pregnant women. Main Outcomes and Measures:Preterm birth (<37 gestational weeks). Gestational age was assessed using the time since the first day of the last menstrual period. Cox proportional hazards regression analysis was used to examine the associations between trimester-specific PM1 concentrations and PTB after controlling for temperature, seasonality, spatial variation, and individual covariates. Results:Of the 1 300 342 singleton live births at the gestational age of 20 to 45 weeks included in this study, 104 585 (8.0%) were preterm. In fully adjusted models, a PM1 concentration increase of 10 μg/m3 over the entire pregnancy was significantly associated with increased risk of PTB (hazard ratio [HR], 1.09; 95% CI, 1.09-1.10), very PTB as defined as gestational age from 28 through 31 weeks (HR, 1.20; 95% CI, 1.18-1.23), and extremely PTB as defined as 20 through 27 weeks' gestation (HR, 1.29; 95% CI, 1.25-1.34). Pregnant women who were older (30-50 years) at conception (HR, 1.13; 95% CI, 1.11-1.14), were overweight before pregnancy (HR, 1.13; 95% CI, 1.11-1.15), had a rural household registration (HR, 1.09; 95% CI, 1.09-1.10), worked as farmers (HR, 1.10; 95% CI, 1.09-1.11), and conceived in autumn (HR, 1.48; 95% CI, 1.46-1.50) appeared to be more sensitive to PM1 exposure than their counterparts. Conclusions and Relevance:Results from this national cohort study examining more than 1.3 million births indicated that exposure to PM1 air pollution was associated with an increased risk of PTB in China. These findings will provide evidence to inform future research studies, public health interventions, and environmental policies.

Project description:BackgroundPotential modification of the association between maternal particulate matter (PM) exposure and preterm delivery (PTD) by folic acid (FA) supplementation has not been studied.ObjectiveWe examined whether FA supplementation could reduce the risk of PTD associated with maternal exposure to PM in ambient air during pregnancy.MethodIn a cohort study covering 30 of the 31 provinces of mainland China in 2014, 1,229,556 primiparas of Han ethnicity were followed until labor. We collected information on their FA supplementation and pregnancy outcomes and estimated each participant's exposure to PM with diameters of ≤10μm (PM10), 2.5μm (PM2.5), and 1μm (PM1) using satellite remote-sensing based models. Cox proportional hazard regression models were used to examine interactions between FA supplementation and PM exposures, after controlling for individual characteristics.ResultsParticipants who initiated FA ≥3 months prior to pregnancy (38.1%) had a 23% [hazard ratio (HR)=0.77 (95% CI: 0.76, 0.78)] lower risk of PTD than women who did not use preconception FA. Participants with PM concentrations in the highest quartile had a higher risk of PTD [HR=1.29 (95% CI: 1.26, 1.32) for PM1, 1.52 (95% CI: 1.46, 1.58) for PM2.5, and 1.22 (95% CI: 1.17, 1.27) for PM10] than those with exposures in the lowest PM quartiles. Estimated associations with a 10-μg/m3 increase in PM1 and PM2.5 were significantly lower among women who initiated FA ≥3 months prior to pregnancy [HR=1.09 (95% CI: 1.08, 1.10) for both exposures] than among women who did not use preconception FA [HR=1.12 (95% CI: 1.11, 1.13) for both exposures; pinteraction<0.001]. The corresponding association was also significantly lower for a 10-μg/m3 increase in PM10 [HR=1.03 (95% CI: 1.02, 1.03) for FA ≥3 months before pregnancy vs. 1.04 (95% CI: 1.03, 1.04) for no preconception FA; pinteraction<0.001].ConclusionOur findings require confirmation in other populations, but they suggest that initiating FA supplementation ≥3 months prior to pregnancy may lessen the risk of PTD associated with PM exposure during pregnancy among primiparas of Han ethnicity. https://doi.org/10.1289/EHP6386.

Project description:Background: In classrooms high concentrations of particulate matter PM10 were measured. It is unknown whether the hazard of indoor particles is similar to that of the better studied outdoor particles. This study therefore analyzed adverse biological effects of classroom in comparison to outdoor PM10. Methods: Samples were taken from six schools during teaching hours. Genome-wide gene expression in human bronchial BEAS-2B epithelial cells was analyzed, and regulated genes were verified by quantitative PCR. Polycyclic aromatic hydrocarbons (PAH), endotoxin, and cat allergen Fel d 1 were analyzed with standard methods. Enhancement of allergic reactivity by PM10 was confirmed with CD63 upregulation in human primary basophils. Acceleration of human blood coagulation was determined with supernatants of PM10-exposed human peripheral blood monocytes. Results: Indoor PM10 induced SERPINB2 (involved in blood coagulation) and inflammatory genes (like CXCL6, CXCL1, IL6, IL8, all p<0.001). Outdoor PM10 induced xenobiotic metabolizing enzymes (CYP1A1, CYP1B1, TIPARP, all p<0.001). The induction of inflammatory genes by indoor PM10 could be explained by endotoxin (indoor 128.5±42.2EU/mg versus outdoor 13.4±21.5EU/mg, p<0.001), the induction of CYP by outdoor PAH (indoor 8.3±4.9ng/mg versus outdoor 16.7±15.2ng/mg, p<0.01). The induction of SERPINB2 was confirmed by a more rapid human blood coagulation (p<0.05). Indoor PM10 had no effect on the allergic reactivity from human primary basophils, except in cat allergic individuals. This was explained by varying Fel d 1 concentrations in indoor PM10 (p<0.001). Conclusions: Indoor PM10, compared to outdoor PM10, was 6 times higher, had a different composition, and on an equal weight basis induced more inflammatory and allergenic reactions, and accelerated blood coagulation. Outdoor PM10 had significantly lower effects, but induced detoxifying enzymes. Therefore, preliminary interventions for the reduction of classroom PM10 seem reasonable, perhaps by intensified ventilation.

Project description:Background: In classrooms high concentrations of particulate matter PM10 were measured. It is unknown whether the hazard of indoor particles is similar to that of the better studied outdoor particles. This study therefore analyzed adverse biological effects of classroom in comparison to outdoor PM10. Methods: Samples were taken from six schools during teaching hours. Genome-wide gene expression in human bronchial BEAS-2B epithelial cells was analyzed, and regulated genes were verified by quantitative PCR. Polycyclic aromatic hydrocarbons (PAH), endotoxin, and cat allergen Fel d 1 were analyzed with standard methods. Enhancement of allergic reactivity by PM10 was confirmed with CD63 upregulation in human primary basophils. Acceleration of human blood coagulation was determined with supernatants of PM10-exposed human peripheral blood monocytes. Results: Indoor PM10 induced SERPINB2 (involved in blood coagulation) and inflammatory genes (like CXCL6, CXCL1, IL6, IL8, all p<0.001). Outdoor PM10 induced xenobiotic metabolizing enzymes (CYP1A1, CYP1B1, TIPARP, all p<0.001). The induction of inflammatory genes by indoor PM10 could be explained by endotoxin (indoor 128.5M-BM-142.2EU/mg versus outdoor 13.4M-BM-121.5EU/mg, p<0.001), the induction of CYP by outdoor PAH (indoor 8.3M-BM-14.9ng/mg versus outdoor 16.7M-BM-115.2ng/mg, p<0.01). The induction of SERPINB2 was confirmed by a more rapid human blood coagulation (p<0.05). Indoor PM10 had no effect on the allergic reactivity from human primary basophils, except in cat allergic individuals. This was explained by varying Fel d 1 concentrations in indoor PM10 (p<0.001). Conclusions: Indoor PM10, compared to outdoor PM10, was 6 times higher, had a different composition, and on an equal weight basis induced more inflammatory and allergenic reactions, and accelerated blood coagulation. Outdoor PM10 had significantly lower effects, but induced detoxifying enzymes. Therefore, preliminary interventions for the reduction of classroom PM10 seem reasonable, perhaps by intensified ventilation. For genome-wide gene expression analysis, BEAS-2B cells (passage 41) were incubated with 10M-BM-5g/ml PM10 (school 4 indoor and outdoor) for 4, 10 or 24h, all in triplicate. experiment type : time course

Dataset Information

Placental mitochondrial methylation and exposure to airborne particulate matter in the early life environment: An ENVIRONAGE birth cohort study.

Publications

Placental mitochondrial methylation and exposure to airborne particulate matter in the early life environment: An ENVIRONAGE birth cohort study.

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