Dataset Information

Polycyclic aromatic hydrocarbon exposure, obesity and childhood asthma in an urban cohort.

ABSTRACT: Exposure to traffic-related air pollutants, including polycyclic aromatic hydrocarbons (PAHs) from traffic emissions and other combustion sources, and childhood obesity, have been implicated as risk factors for developing asthma. However, the interaction between these two on asthma among young urban children has not been studied previously.Exposure to early childhood PAHs was measured by two week residential indoor monitoring at age 5-6 years in the Columbia Center for Children's Environmental Health birth cohort (n=311). Semivolatile [e.g., methylphenanthrenes] and nonvolatile [e.g., benzo(a)pyrene] PAHs were monitored. Obesity at age 5 was defined as a body mass index (BMI) greater than or equal to the 95th percentile of the year 2000 age- and sex-specific growth charts (Center for Disease Control). Current asthma and recent wheeze at ages 5 and 7 were determined by validated questionnaires. Data were analyzed using a modified Poisson regression in generalized estimating equations (GEE) to estimate relative risks (RR), after adjusting for potential covariates.Neither PAH concentrations or obesity had a main effect on asthma or recent wheeze. In models stratified by presence/absence of obesity, a significant positive association was observed between an interquartile range (IQR) increase in natural log-transformed 1-methylphenanthrene (RR [95% CI]: 2.62 [1.17-5.88] with IQRln=0.76), and 9-methylphenanthrene (2.92 [1.09-7.82] with IQRln=0.73) concentrations and asthma in obese children (n=63). No association in non-obese (n=248) children was observed at age 5 (Pinteraction<0.03). Similar associations were observed for 3-methylphenanthrene, 9-methylphenanthrene, and 3,6-dimethylphenanthrene at age 7.Obese young children may be more likely to develop asthma in association with greater exposure to PAHs, and methylphenanthrenes in particular, than non-obese children.

SUBMITTER: Jung KH

PROVIDER: S-EPMC3912566 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

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Polycyclic aromatic hydrocarbon exposure, obesity and childhood asthma in an urban cohort.

Jung Kyung Hwa KH Perzanowski Matthew M Rundle Andrew A Moors Kathleen K Yan Beizhan B Chillrud Steven N SN Whyatt Robin R Camann David D Perera Frederica P FP Miller Rachel L RL

Environmental research 20131227

<h4>Background</h4>Exposure to traffic-related air pollutants, including polycyclic aromatic hydrocarbons (PAHs) from traffic emissions and other combustion sources, and childhood obesity, have been implicated as risk factors for developing asthma. However, the interaction between these two on asthma among young urban children has not been studied previously.<h4>Methods</h4>Exposure to early childhood PAHs was measured by two week residential indoor monitoring at age 5-6 years in the Columbia Ce ...[more]

PMID: 24407477

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Project description:There is increased emphasis on understanding cumulative risk from the combined effects of chemical and non-chemical stressors as it relates to public health. Recent animal studies have identified pulmonary inflammation as a possible modifier and risk factor for chemical toxicity in the lung after exposure to inhaled pollutants; however, little is known about specific interactions and potential mechanisms of action. In this study, primary human bronchial epithelial cells (HBEC) cultured in 3D at the air-liquid interface (ALI) are utilized as a physiologically relevant model to evaluate the effects of inflammation on toxicity of polycyclic aromatic hydrocarbons (PAHs), a class of contaminants generated from incomplete combustion of fossil fuels. Normal HBEC were differentiated in the presence of IL-13 for 14 days to induce a profibrotic phenotype similar to asthma. Fully differentiated normal and asthmatic phenotype HBEC were treated with benzo[a]pyrene (BAP; 1 – 40 ug/mL) or 1% DMSO/PBS vehicle at the ALI for 48 hrs. Cells were evaluated for cytotoxicity, barrier integrity, and transcriptional biomarkers of chemical metabolism and inflammation by quantitative PCR. Cells with the asthmatic phenotype treated with BAP show some significant (p<0.05) increase in cytotoxicity and significantly (p<0.05) decreased barrier integrity compared to normal cells. Asthmatic phenotype cells also showed increase sensitivity to BAP metabolism compared to cells with the normal phenotype. Additionally, RNA sequencing data showed that a large number of genes were uniquely significantly expressed in cells with the induced asthmatic phenotype exposed to BAP. Future studies will further explore mechanisms of toxicity from global transcriptomics and investigate the role of microRNA in mediating mechanisms of toxicity and inflammation. These data are the first to evaluate the role of combined environmental factors associated with inflammation from pre-existing disease and PAH exposure on pulmonary toxicity in a physiologically relevant human in vitro model.

Project description:BackgroundEpidemiological studies have found that prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with increased risk for neural tube defects (NTDs). Aberrant DNA methylation, excessive apoptosis, and oxidative stress have been implied as the mechanism underlying the association between PAH exposure and NTDs, respectively. However, the role of DNA methylation aberration of apoptotic initiator CASP8 (caspase-8, apoptosis-related cysteine peptidase) in the formation of NTDs in association with PAH exposure is not known. By combining a case-control study and mouse model, we aimed to explore the full spectrum of the links from PAH exposure, oxidative stress, CASP8 methylation change, caspase-8 activation, apoptosis, to NTD formation.ResultsHypomethylation of CASP8 promoter was noticed in the microarray profiled by Infinium HumanMethylation450 BeadChip using neural tissues from 10 terminated NTD fetuses and 8 terminated non-malformed fetuses (14 CpG sites, with β difference ranging between 8.8 and 26.3%), and was validated in a larger case-control sample performed with neural tissues from 80 NTD cases and 32 non-malformed fetuses, using the Sequenom MassARRAY system (7 CpG sites). Hypomethylation of CASP8 was a risk factor for NTDs (aOR = 1.11; 95% CI, 1.05-1.17) based on the logistic regression model. According to Pearson's correlation, methylation levels of CASP8 were inversely correlated with PAH concentrations in maternal serum and with oxidative stress markers in fetal neural tissues (p < 0.05). In the animal study, increased NTD rates (13.5% frequency), Casp8 hypomethylation, caspase-8 upregulation, increased caspase-8 cleavage, and excessive apoptosis were found in mouse embryos cultured with benz(a)pyrene (BaP) in vitro. Antioxidant N-acetyl-L-cysteine (NAC) and BaP co-treatment attenuated the changes found in BaP treatment group.ConclusionsHypomethylation of Casp8 promoter is associated with the formation of NTDs, and Casp8 hypomethylation may be induced by oxidative stress that resulted from exposure to PAHs.

Project description:1-Nitro-pyrene has been considered a compound specific to diesel combustion emission, while 1- and 2-nitro-napthalene are mainly produced through photochemical conversion of naphthalene released to the atmosphere. Metabolites of these compounds may serve as biomarkers of exposure to traffic related pollutants. We collected urine samples from 111 healthy and non-smoking subjects within (i.e., during the Beijing Olympics) and outside (i.e., before and after the Olympics) a traffic control regime to improve Beijing's air quality. Urines were analyzed for the sum of 1&2-amino-naphthalene (metabolites of 1- and 2-nitro-naphthalene) and 1-amino-pyrene (a metabolite of 1-nitro-pyrene), using an HPLC-fluorescence method. Within the same time periods, PM2.5 mass and constituents were measured, including elemental carbon, sulfate, nitrate, PAHs, carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, and particle number concentrations. The associations between the urinary metabolites and air pollutants were analyzed using linear mixed-effects models. From the pre- to during-Olympic period, 1&2-amino-naphthalene and 1-hydroxy-pyrene decreased by 23% (p=0.066) and 16% (p=0.049), respectively, while there was no change in 1-amino-pyrene (2% increase, p=0.892). From during- to post-Olympic period, 1&2-amino-naphthalene, 1-amino-pyrene and 1-hydroxy-pyrene concentrations increased by 26% (p=0.441), 37% (p=0.355), and 3% (p=0.868), respectively. Furthermore, 1&2-amino-naphthalene and 1-hydroxy-pyrene were associated with traffic related pollutants in a similar lag pattern. 1-amino-pyrene was associated more strongly with diesel combustion products (e.g. PN and elemental carbon) and not affected by season. Time-lag analyses indicate strongest/largest associations occurred 24-72h following exposure. 1&2-amino-naphthalene and 1-hydroxy-pyrene can be used as a biomarker of exposure to general vehicle-emitted pollutants. More data are needed to confirm 1-amino-pyrene as a biomarker of exposure to diesel combustion emissions. Controlling creatinine as an independent variable in the models will provide a moderate adjusting effect on the biomarker analysis.

Dataset Information

Polycyclic aromatic hydrocarbon exposure, obesity and childhood asthma in an urban cohort.

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Polycyclic aromatic hydrocarbon exposure, obesity and childhood asthma in an urban cohort.

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