Genome-Wide Analysis of DNA Methylation and Acute Coronary Syndrome.

RATIONALE: Acute coronary syndrome (ACS) is a leading cause of death worldwide. Immune functions play a vital role in ACS development; however, whether epigenetic modulation contributes to the regulation of blood immune cells in this disease has not been investigated. OBJECTIVE: We conducted an epigenome-wide analysis with circulating immune cells to identify differentially methylated genes in ACS. METHODS AND RESULTS: We examined genome-wide methylation of whole blood in 102 ACS patients and 101 controls using HumanMethylation450 array, and externally replicated significant discoveries in 100 patients and 102 controls. For the replicated loci, we further analyzed their association with ACS in 6 purified leukocyte subsets, their correlation with the expressions of annotated genes, and their association with cardiovascular traits/risk factors. We found novel and reproducible association of ACS with blood methylation at 47 cytosine-phosphoguanine sites (discovery: false discovery rate <0.005; replication: Bonferroni corrected P<0.05). The association of methylation levels at these cytosine-phosphoguanine sites with ACS was further validated in at least 1 of the 6 leukocyte subsets, with predominant contributions from CD8+ T cells, CD4+ T cells, and B cells. Blood methylation of 26 replicated cytosine-phosphoguanine sites showed significant correlation with expressions of annotated genes (including IL6R, FASLG, and CCL18; P<5.9×10-4), and differential gene expression in case versus controls corroborated the observed differential methylation. The replicated loci suggested a role in ACS-relevant functions including chemotaxis, coronary thrombosis, and T-cell-mediated cytotoxicity. Functional analysis using the top ACS-associated methylation loci in purified T and B cells revealed vital pathways related to atherogenic signaling and adaptive immune response. Furthermore, we observed a significant enrichment of the replicated cytosine-phosphoguanine sites associated with smoking and low-density lipoprotein cholesterol (Penrichment≤1×10-5). CONCLUSIONS: Our study identified novel blood methylation alterations associated with ACS and provided potential clinical biomarkers and therapeutic targets. Our results may suggest that immune signaling and cellular functions might be regulated at an epigenetic level in ACS.

[Association between urinary polycyclic aromatic hydrocarbon metabolites and elevated serum uric acid levels in coke oven workers].

OBJECTIVE: To analyze the relationship between metabolites of polycyclic aromatic hydrocarbons (PAHs) and serum uric acid levels in coke oven workers and to provide new clues to the pathogenic mechanism of PAHs. METHODS: A total of 1302 coke oven workers were divided into four groups, namely control group and low-, intermediate-, and high-dose exposure groups. The concentrations of ambient PAHs at each workplace were determined by high-performance liquid chromatography. The detailed information on the occupational history and health of workers was collected by questionnaire survey and physical examination, and so were their blood and urine samples. Serum uric acid and creatinine levels were measured using a Hitachi 7020 automatic biochemical analyzer. Ten urinary PAH metabolites were detected by gas chromatography-mass spectrometry. RESULTS: Serum uric acid levels were the highest in the high-dose exposure group, followed by the intermediate- and low-dose exposure groups, and were the lowest in the control group. There were significant correlations between serum uric acid levels and the quartiles of 1-hydroxynaphthalene and 1-hydroxyphenanthrene (P < 0.05). After adjustment for PAH metabolite-related relationship, only urinary 1-hydroxyphenanthrene was significantly correlated with serum uric acid levels (P = 0.001). After adjustment for confounding factors and using the 1st quartile of 1-hydroxyphenanthrene as a reference, the odds ratio for hyperuricemia in subjects with the 2nd, 3rd, and 4th quartiles of 1-hydroxyphenanthrene were 1.55, 1.57, and 2.35, respectively. CONCLUSION: Urinary 1-hydroxyphenanthrene is associated with a dose-response increase in serum uric acid levels in coke oven workers, and exposure to phenanthrene in PAHs may be a risk factor for hyperuricemia.

Genome-wide association study on serum alkaline phosphatase levels in a Chinese population.

BACKGROUND: Serum alkaline phosphatase (ALP) is a complex phenotype influenced by both genetic and environmental factors. Recent Genome-Wide Association Studies (GWAS) have identified several loci affecting ALP levels; however, such studies in Chinese populations are limited. We performed a GWAS analyzing the association between 658,288 autosomal SNPs and serum ALP in 1,461 subjects, and replicated the top SNPs in an additional 8,830 healthy Chinese Han individuals. The interactions between significant locus and environmental factors on serum ALP levels were further investigated. RESULTS: The association between ABO locus and serum ALP levels was replicated (P = 2.50 × 10⁻²¹, 1.12 × 10⁻56 and 2.82 × 10⁻²7 for SNP rs8176720, rs651007 and rs7025162 on ABO locus, respectively). SNP rs651007 accounted for 2.15% of the total variance of serum ALP levels independently of the other 2 SNPs. When comparing our findings with previously published studies, ethnic differences were observed across populations. A significant interaction between ABO rs651007 and overweight and obesity was observed (FDR for interaction was 0.036); for individuals with GG genotype, those with normal weight and those who were overweight or obese have similar serum ALP concentrations; minor allele A of rs651007 remarkably reduced serum ALP levels, but this effect was attenuated in overweight and obese individuals. CONCLUSIONS: Our findings indicate that ABO locus is a major determinant for serum ALP levels in Chinese Han population. Overweight and obesity modifies the effect of ABO locus on serum ALP concentrations.

[Association between genetic polymorphisms in pre-miR-146a and pre-miR-196a2 and genetic damage levels among coke oven workers].

OBJECTIVE: To investigate the association of rs2910164 G > C polymorphism and rs11614913 T > C polymorphism in pre-miR-146a and pre-miR-196a2 with genetic damage levels in coke oven workers. METHODS: A total of 575 nonsmoking workers who have worked for more than one year in a coke-oven plant at Wuhan, Hubei Province were enrolled in this study in September to October, 2010. The general characteristics as well as blood and urine samples were collected. The genetic damage levels were detected by cytokinesis-block micronucleus cytom assay and represented as micronucleus (MN) frequencies of binucleate cells in peripheral blood lymphocytes. The rs2910164 G > C polymorphisms in pre-miR-146a and rs11614913 T > C polymorphisms in pre-miR-196a2 were genotyped by using TaqMan assay. The plasma concentrations of benzo[a]pyrene-diolepoxide (BPDE)-albumin adducts were determined by using ELISA. All data were analyzed, the frequency ratio (FR) and 95%CI were calculated. RESULTS: Totally, 575 workers were taken into consideration. The rs2910164 C allele was associated with increased MN frequencies in the coke oven workers (P trend = 0.025), and the MN frequencies were higher in rs2910164 CC genotype carriers (4.38 ± 3.46) than in wild-type rs2910164 GG genotype carriers (4.02 ± 3.09) (FR = 1.18, 95%CI:1.04-1.34). The further stratified analyses by working years, gender, alcohol consumption, and the levels of BPDE-albumin adducts showed that the effects of rs2910164 C allele in increasing MN frequencies were robust in subjects who were males (FR = 1.11, 95%CI:1.02-1.20), nondrinkers (FR = 1.07, 95%CI:1.00-1.14), working years less than 20 (FR = 1.12, 95%CI:1.03-1.22), and workers with lower BPDE-albumin adducts levels (FR = 1.11, 95%CI:1.02-1.21) (P trend = 0.011, 0.044, 0.006 and 0.020, respectively). In addition, the MN frequencies were higher in workers with rs11614913 TC genotype (4.27 ± 2.91) than workers with rs11614913 TT genotype (3.90 ± 3.32) (FR = 1.12, 95%CI:1.02-1.23).Workers carried both rs2910164 GG and rs11614913 TT genotypes were set as a control, and the MN frequencies of workers with both rs2910164 CC and rs11614913 CC genotypes (5.32 ± 4.94) were 1.51 (1.21-1.89) times higher than the control (3.75 ± 3.01). CONCLUSION: The rs2910164 C allele in pre-miR-146a and rs11614913 C allele in pre-miR-196a2 were associated with increased genetic damage levels in coke oven workers.

Risk assessment and source apportionment of heavy metals pollution from atmospheric deposition in Nanjing, China.

Heavy metals (HMs) are the toxic pollutants in urban environment, and their sources are complex. Dust might be a good carrier of HMs into ecosystem and human. In this study, 48 dust samples were collected in Nanjing, an industrial city and transportation hub in the Yangtze River Delta, China. The concentrations, spatial distribution, sources and risks of heavy metals (Cr, Ni, Cu, Zn, Cd and Pb) in dust were determined and analyzed. The results showed that although the health risks of some HMs had decreased, Cr, Zn, and Cd had high concentrations and high risks on ecosystem/human. And thus, the total risks of the target HMs were higher than the threshold of non-risks. Especially, children may face the highest possible risks due to the frequent hand-oral ingestion when children play. The hot spot regions of the HMs were mainly in the industrial district in the north, urban, and rural region in south, relating with the industrial, traffic, and agricultural sources, respectively. The analysis for the risks of individual sources further confirmed these sources should be further controlled. The results in this study will provide information on the priority of HMs' monitoring and source management.

Exposure to Polycyclic Aromatic Hydrocarbons and Accelerated DNA Methylation Aging.

BACKGROUND: Aging is related to an increased risk of morbidity and mortality and is affected by environmental factors. Exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with adverse health outcomes; but the association of such exposure with DNA methylation aging, a novel aging marker, is unclear. OBJECTIVES: Our aim was to investigate the association of PAH exposure with methylation aging. METHODS: We trained and validated a methylation age predictor suitable for Chinese populations using whole blood methylation data in 989 Chinese and 160 Caucasians. We defined two aging indicators: δage, as methylation age minus chronological age; and aging rate, the ratio of methylation to chronological age. The association of PAH exposure with aging indicators was evaluated using linear regressions in three panels of healthy Chinese participants (N=539, among the aforementioned 989 Chinese participants) whose exposure levels were assessed by 10 urinary monohydroxy-PAH metabolites. RESULTS: We developed a methylation age predictor providing accurate predictions in both Chinese individuals and Caucasian persons (R=0.94-0.96, RMSE=3.8-4.3). Among the 10 urinary metabolites that we measured, 1-hydroxypyrene and 9-hydroxyphenanthrene were associated with methylation aging independently of other OH-PAHs and risk factors; 1-unit increase in 1-hydroxypyrene was associated with a 0.53-y increase in Δage [95% confidence interval (CI): 0.18, 0.88; false discovery rate (FDR) FDR=0.004] and 1.17% increase in aging rate (95% CI: 0.36, 1.98; FDR=0.02), whereas for 9-hydroxyphenanthrene, the increase was 0.54-y for Δage (95% CI: 0.17, 0.91; FDR=0.004), and 1.15% for aging rate (95% CI: 0.31, 1.99; FDR=0.02). The association direction was consistent across the three Chinese panels with the association magnitude correlating with the panels' exposure levels; the association was validated by methylation data of purified leukocytes. Several cytosine-phosphoguanines, including those located on FHL2 and ELOVL2, were found associated with both aging indicators and monohydroxy-PAH levels. CONCLUSIONS: We developed a methylation age predictor specific for Chinese populations but also accurate for Caucasian populations. Our findings suggest that exposure to PAHs may be associated with an adverse impact on human aging and epigenetic alterations in Chinese populations. https://doi.org/10.1289/EHP2773.

Genome-Wide Analysis of DNA Methylation and Cigarette Smoking in a Chinese Population.

BACKGROUND: Smoking is a risk factor for many human diseases. DNA methylation has been related to smoking, but genome-wide methylation data for smoking in Chinese populations is limited. OBJECTIVES: We aimed to investigate epigenome-wide methylation in relation to smoking in a Chinese population. METHODS: We measured the methylation levels at > 485,000 CpG sites (CpGs) in DNA from leukocytes using a methylation array and conducted a genome-wide meta-analysis of DNA methylation and smoking in a total of 596 Chinese participants. We further evaluated the associations of smoking-related CpGs with internal polycyclic aromatic hydrocarbon (PAH) biomarkers and their correlations with the expression of corresponding genes. RESULTS: We identified 318 CpGs whose methylation levels were associated with smoking at a genome-wide significance level (false discovery rate < 0.05), among which 161 CpGs annotated to 123 genes were not associated with smoking in recent studies of Europeans and African Americans. Of these smoking-related CpGs, methylation levels at 80 CpGs showed significant correlations with the expression of corresponding genes (including RUNX3, IL6R, PTAFR, ANKRD11, CEP135 and CDH23), and methylation at 15 CpGs was significantly associated with urinary 2-hydroxynaphthalene, the most representative internal monohydroxy-PAH biomarker for smoking. CONCLUSION: We identified DNA methylation markers associated with smoking in a Chinese population, including some markers that were also correlated with gene expression. Exposure to naphthalene, a byproduct of tobacco smoke, may contribute to smoking-related methylation. CITATION: Zhu X, Li J, Deng S, Yu K, Liu X, Deng Q, Sun H, Zhang X, He M, Guo H, Chen W, Yuan J, Zhang B, Kuang D, He X, Bai Y, Han X, Liu B, Li X, Yang L, Jiang H, Zhang Y, Hu J, Cheng L, Luo X, Mei W, Zhou Z, Sun S, Zhang L, Liu C, Guo Y, Zhang Z, Hu FB, Liang L, Wu T. 2016. Genome-wide analysis of DNA methylation and cigarette smoking in Chinese. Environ Health Perspect 124:966-973; http://dx.doi.org/10.1289/ehp.1509834.

Urinary metals and heart rate variability: a cross-sectional study of urban adults in Wuhan, China.

BACKGROUND: Epidemiological studies have suggested an association between external estimates of exposure to metals in air particles and altered heart rate variability (HRV). However, studies on the association between internal assessments of metals exposure and HRV are limited. OBJECTIVES: The purpose of this study was to examine the potential association between urinary metals and HRV among residents of an urban community in Wuhan, China. METHODS: We performed a cross-sectional analysis of 23 urinary metals and 5-min HRV indices (SDNN, standard deviation of normal-to-normal intervals; r-MSSD, root mean square of successive differences in adjacent normal-to-normal intervals; LF, low frequency; HF, high frequency; TP, total power) using baseline data on 2,004 adult residents of Wuhan. RESULTS: After adjusting for other metals, creatinine, and other covariates, natural log-transformed urine titanium concentration was positively associated with all HRV indices (all p < 0.05). Moreover, we estimated negative associations between cadmium and r-MSSD, LF, HF, and TP; between lead and r-MSSD, HF, and TP; and between iron, copper, and arsenic and HF, SDNN, and LF, respectively, based on models adjusted for other metals, creatinine, and covariates (all p < 0.10). Several associations differed according to cardiovascular disease risk factors. For example, negative associations between cadmium and r-MSSD were stronger among participants ≤ 52 years of age (vs. > 52), current smokers (vs. nonsmokers), body mass index < 25 kg/m2 (vs. ≥ 25), and among those who were not hypertensive. CONCLUSIONS: Urine concentrations of several metals were associated with HRV parameters in our cross-sectional study population. These findings need replication in other studies with adequate sample sizes.

Associations between 25 lung cancer risk-related SNPs and polycyclic aromatic hydrocarbon-induced genetic damage in coke oven workers.

BACKGROUND: Genome-wide association studies (GWAS) have identified multiple single-nucleotide polymorphisms (SNP) associated with lung cancer. However, whether these SNPs are associated with genetic damage, a crucial event in cancer initiation and evolution, is still unknown. We aimed to establish associations between these SNPs and genetic damage caused by the ubiquitous carcinogens, polycyclic aromatic hydrocarbons (PAH). METHODS: We cross-sectionally investigated the associations between SNPs from published GWAS for lung cancer in Asians and PAH-induced genetic damage in 1,557 coke oven workers in China. Urinary PAH metabolites, plasma benzo[a]pyrene-r-7,t-8,c-10-tetrahydrotetrol-albumin (BPDE-Alb) adducts, urinary 8-hydroxydeoxyguanosine (8-OHdG), and micronuclei (MN) frequency were determined by gas chromatography-mass spectrometry, sandwich ELISA, high-performance liquid chromatography, and cytokinesis-block micronucleus assay, respectively. RESULTS: 13q12.12-rs753955C was suggestively associated with elevated 8-OHdG levels (P = 0.003). Higher 8-OHdG levels were observed in individuals with rare allele homozygotes (CC) than in TT homozygotes (ß, 0.297; 95% confidence interval, 0.124-0.471; P = 0.001). 9p21-rs1333040C, 10p14-rs1663689G, and 15q25.1-rs3813572G were significantly associated with lower MN frequency (P values were 0.002, 0.001, and 0.005, respectively). 10p14-rs1663689G polymorphism downregulated the relationship of the total concentration of PAH metabolites to 8-OHdG levels (Pinteraction = 0.002). TERT-rs2736100G and VTI1A-rs7086803A aggravated the relationship of BPDE-Alb adducts to MN frequency, whereas BPTF-rs7216064G attenuated that correlation (all Pinteraction < 0.001). CONCLUSIONS: Lung cancer risk-associated SNPs and their correlations with PAH exposure were associated with 8-OHdG levels and MN frequency. IMPACT: Lung cancer risk-associated SNPs might influence one's susceptibility to genetic damage caused by PAHs. Cancer Epidemiol Biomarkers Prev; 23(6); 986-96. ©2014 AACR.