Blood Leukocyte DNA Methylation Predicts Risk of Future Myocardial Infarction and Coronary Heart Disease

BACKGROUND: DNA methylation is implicated in coronary heart disease (CHD), but current evidence is based on small, cross-sectional studies. We examined blood DNA methylation in relation to incident CHD across multiple prospective cohorts. METHODS: Nine population-based cohorts from the United States and Europe profiled epigenome-wide blood leukocyte DNA methylation using the Illumina Infinium 450k microarray, and prospectively ascertained CHD events including coronary insufficiency/unstable angina, recognized myocardial infarction, coronary revascularization, and coronary death. Cohorts conducted race-specific analyses adjusted for age, sex, smoking, education, body mass index, blood cell type proportions, and technical variables. We conducted fixed-effect meta-analyses across cohorts. RESULTS: Among 11 461 individuals (mean age 64 years, 67% women, 35% African American) free of CHD at baseline, 1895 developed CHD during a mean follow-up of 11.2 years. Methylation levels at 52 CpG (cytosine-phosphate-guanine) sites were associated with incident CHD or myocardial infarction (false discovery rate<0.05). These CpGs map to genes with key roles in calcium regulation (ATP2B2, CASR, GUCA1B, HPCAL1), and genes identified in genome- and epigenome-wide studies of serum calcium (CASR), serum calcium-related risk of CHD (CASR), coronary artery calcified plaque (PTPRN2), and kidney function (CDH23, HPCAL1), among others. Mendelian randomization analyses supported a causal effect of DNA methylation on incident CHD; these CpGs map to active regulatory regions proximal to long non-coding RNA transcripts. CONCLUSION: Methylation of blood-derived DNA is associated with risk of future CHD across diverse populations and may serve as an informative tool for gaining further insight on the development of CHD

Pulmonary Function and Blood DNA Methylation A Multiancestry Epigenome-Wide Association Meta-analysis

Rationale: Methylation integrates factors present at birth and modifiable across the lifespan that can influence pulmonary function. Studies are limited in scope and replication. Objectives: To conduct large-scale epigenome-wide meta-analyses of blood DNA methylation and pulmonary function. Methods: Twelve cohorts analyzed associations of methylation at cytosine-phosphate-guanine probes (CpGs), using Illumina 450K or EPIC/850K arrays, with FEV1, FVC, and FEV1/FVC. We performed multiancestry epigenome-wide meta-analyses (total of 17,503 individuals; 14,761 European, 2,549 African, and 193 Hispanic/Latino ancestries) and interpreted results using integrative epigenomics. Measurements and Main Results: We identified 1,267 CpGs (1,042 genes) differentially methylated (false discovery rate,,0.025) in relation to FEV1, FVC, or FEV1/FVC, including 1,240 novel and 73 also related to chronic obstructive pulmonary disease (1,787 cases). We found 294 CpGs unique to European or African ancestry and 395 CpGs unique to never or ever smokers. The majority of significant CpGs correlated with nearby gene expression in blood. Findings were enriched in key regulatory elements for gene function, including accessible chromatin elements, in both blood and lung. Sixty-nine implicated genes are targets of investigational or approved drugs. One example novel gene highlighted by integrative epigenomic and druggable target analysis is TNFRSF4. Mendelian randomization and colocalization analyses suggest that epigenome-wide association study signals capture causal regulatory genomic loci. Conclusions: We identified numerous novel loci differentially methylated in relation to pulmonary function; few were detected in large genome-wide association studies. Integrative analyses highlight functional relevance and potential therapeutic targets. This comprehensive discovery of potentially modifiable, novel lung function loci expands knowledge gained from genetic studies, providing insights into lung pathogenesis

Systemic inflammation and lung function decline in a repeated measure study on an elderly cohort

RATIONALE Decreased lung function has been linked to increased inflammation and oxidative stress. Higher C-reactive protein (CRP) levels have been associated with lower lung function in cross-sectional studies. Whether CRP, as a marker of systemic inflammation, is related with lung function decline is unresolved. METHODS We investigated the association of CRP levels on lung function decline on 2,014 lung function measurements on 803 elderly men from the Eastern Massachusetts Normative Aging Study, whose lung function (forced vital capacity [FVC] and forced expiratory volume in one second [FEV1]) was measured 2-4 times between 1995-2005. Subjects were categorized according to the median CRP level (1.61 mg/L). We used mixed linear models to estimate FVC or FEV1 decline by CRP category, adjusting for potential confounders. RESULTS FVC decline was 22.1 mL/yr (95% CI 16.7-27.4) in subjects with CRP>1.61 mg/L, while subjects with CRP1.61 mg/L, while those with CRP>1.61 mg/L had a FEV1 decline of 11.3 mL/yr (95% CI 7.5-15.0). The effect of CRP on FEV decline was also was significant (p=0.01). CONCLUSIONS Our results indicate that higher CRP levels are associated with a decline in lung function in the elderly

Aging and epigenetics : longitudinal changes in gene-specific DNA methylation

DNA methylation has been associated with age-related disease. Intra-individual changes in gene-specific DNA methylation over time in a community-based cohort has not been well described. We estimated the change in DNA methylation due to aging for nine genes in an elderly, community-dwelling cohort of men. Seven hundred and eighty four men from the Veterans Administration Normative Aging Study who were living in metropolitan Boston from 1999-2009 donated a blood sample for DNA methylation analysis at clinical examinations repeated at approximately 3-5 year intervals. We used mixed effects regression models. Aging was significantly associated with decreased methylation of GCR, iNOS and TLR2 and with increased methylation of IFN\u3b3, F3, CRAT and OGG. Obstructive pulmonary disease at baseline modified the effect of aging on methylation of IFN\u3b3 (interaction p = 0.04). For participants who had obstructive pulmonary disease at their baseline visit, the rate of change of methylation of IFN\u3b3 was -0.05% 5-methyl-cytosine (5-mC) per year (95% CI: -0.22, 0.13), but was 0.14% 5-mC per year (95% CI: 0.05, 0.24) for those without this condition. Models with random slopes indicated significant heterogeneity in the effect of aging on methylation of GCR, iNOS and OGG. These findings suggest that DNA methylation may reflect differential biological agin

Air pollution, obesity, genes and cellular adhesion molecules

OBJECTIVES: Particulate matter has been associated with acute cardiovascular outcomes, but our understanding of the mechanism is incomplete. We examined the association between particulate matter and cell adhesion molecules. We also investigated the modifying effect of genotype and phenotype variation to gain insight into the relevant biological pathways for this association. METHODS: We used mixed regression models to examine the association of PM(2.5) (particulate matter < or = 2.5 microm in diameter) and black carbon with serum concentrations of soluble intercellular adhesion molecule (sICAM-1) and soluble vascular cell adhesion molecule (sVCAM-1), markers of endothelial function and inflammation, in a longitudinal study of 809 participants in the Normative Ageing Study (1819 total observations). We also examined whether this association was modified by genotype, obesity or diabetes status. Genes selected for analyses were either related to oxidative stress, endothelial function, lipid metabolism or metal processing. RESULTS: Black carbon during the 2 days prior to blood draw was significantly associated with increased sVCAM-1 (4.5% increase per 1 microg/m(3), 95% CI 1.1 to 8.0). Neither pollutant was associated with sICAM-1. Larger effects of black carbon on sVCAM were seen in subjects with obesity (p=0.007) and who were GSTM1 null (p=0.02). CONCLUSIONS: Black carbon is associated with markers of endothelial function and inflammation. Genes related to oxidative defence may modify this association

Ozone exposure, antioxidant genes, and lung function in an elderly cohort : VA normative aging study

Background: Ozone (O3) exposure is known to cause oxidative stress. This study investigated the acute effects of O3 on lung function in the elderly, a suspected risk group. It then investigated whether genetic polymorphisms of antioxidant genes (heme oxygenase-1 (HMOX1) and glutathione 5-transferase pi (GSTP1)] modified these associations. Methods: 1100 elderly men from the Normative Aging Study were examined whose lung function (forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1)) was measured every 3 years from 1995 to 2005. The study genotyped the GSTP1 lle105Val and Ala114Val polymorphisms and the (GT)n repeat polymorphism in the HMOX1 promoter, classifying repeats as short (n<25) or long (n 6525). Ambient O3 was measured continuously at locations in the Greater Boston area. Mixed linear models were used, adjusting for known confounders. Results: A 15 ppb increase in O3 during the previous 48 h was associated with a 1.25% decrease in FEV1 (95% CI: -1.96% to -0.54%). This estimated effect was worsened with either the presence of a long (GT)n repeat in HMOX1 (-1.38%, 95% CI: -2.11% to -0.65%) or the presence of an allele coding for Val105 in GSTP1 (-1.69%, 95% CI: -2.63% to -0.75%). A stronger estimated effect of O3 on FEV1 was found in subjects carrying both the GSTP1 105Val variant and the HMOX1 long (GT)n repeat (-1.94%, 95% CI: -2.89% to -0.98%). Similar associations were also found between FVC and O3 exposure. Conclusions: Our results suggest that O3 has an acute effect on lung function in the elderly, and the effects may be modified by the presence of specific polymorphisms in antioxidant genes

Beyond the mean: Quantile regression to explore the association of air pollution with gene-specific methylation in the normative aging study.

BACKGROUND: Air pollution has been related to mean changes in outcomes, including DNA methylation. However, mean regression analyses may not capture associations that occur primarily in the tails of the outcome distribution. OBJECTIVES: This study examined whether the association between particulate air pollution and DNA methylation differs across quantiles of the methylation distribution. We focused on methylation of candidate genes related to coagulation and inflammation: coagulation factor III (F3), intercellular adhesion molecule 1 (ICAM-1), interferon gamma (IFN-&gamma;), interleukin-6 (IL-6), and toll-like receptor 2 (TRL-2). METHODS: We measured gene-specific blood DNA methylation repeatedly in 777 elderly men participating in the Normative Aging Study (1999-2010). We fit quantile regressions for longitudinal data to investigate whether the associations of particle number, PM2.5 black carbon, and PM2.5 mass concentrations (4-weeks moving average) with DNA methylation [expressed as the percentage of methylated cytosines over the sum of methylated and unmethylated cytosines at position 5 (%5mC)] varied across deciles of the methylation distribution. We reported the quantile regression coefficients which corresponded to absolute differences in DNA methylation (expressed in %5mC) associated with an interquartile range increase in air pollution concentration. RESULTS: Interquartile range increases in particle number, PM2.5 black carbon, and PM2.5 mass concentrations were associated with significantly lower methylation in the lower tails of the IFN-&gamma; and ICAM-1 methylation distributions. For instance, a 3.4 &micro;g/m(3) increase in PM2.5 mass concentration was associated with a 0.18%5mC (95% CI: -0.30, -0.06) decrease on the 20th percentile of ICAM-1 methylation, but was not significantly related to the 80th percentile (Estimate: 0.07%5mC, 95% CI: -0.09, 0.24). CONCLUSIONS: In our study population of older men, air pollution exposures were associated with a left shift in the lower tails of the IFN-&gamma; and ICAM-1 methylation distributions

Air pollution and DNA methylation: interaction by psychological factors in the VA Normative Aging Study

DNA methylation is a potential pathway linking air pollution to disease. Studies indicate that psychological functioning modifies the association between pollution and morbidity. The authors estimated the association of DNA methylation with ambient particulate matter less than 2.5 \ub5m in diameter (PM(2.5)) and black carbon, using mixed models. DNA methylation of the inducible nitric oxide synthase gene, iNOS, and the glucocorticoid receptor gene, GCR, was measured by quantitative polymerase chain reaction pyrosequencing of 1,377 blood samples from 699 elderly male participants in the VA Normative Aging Study (1999-2009). The authors also investigated whether this association was modified by psychological factors including optimism or pessimism, anxiety, and depression. iNOS methylation was decreased after acute exposure to both black carbon and PM(2.5). A 1-\u3bcg/m(3) increase in exposure to black carbon in the 4 hours preceding the clinical examination was associated with a 0.9% decrease in 5-methylcytosine (95% CI: 0.4, 1.4) in iNOS, and a 10-\u3bcg/m(3) increase in exposure to PM(2.5) was associated with a 0.6% decrease in 5-methylcytosine (95% CI: 0.03, 1.1) in iNOS. Participants with low optimism and high anxiety had associations that were 3-4 times larger than those with high optimism or low anxiety. GCR methylation was not associated with particulate air pollution exposure

Air pollution and homocysteine : more evidence that oxidative stress-related genes modify effects of particulate air pollution

BACKGROUND: Ambient particles are associated with cardiovascular events and recently with total plasma homocysteine. High total plasma homocysteine is a risk for human health. However, the biologic mechanisms are not fully understood. One of the putative pathways is through oxidative stress. We aimed to examine whether associations of PM2.5 and black carbon with homocysteine were modified by genotypes including HFE H63D, C282Y, CAT (rs480575, rs1001179, rs2284367, and rs2300181), NQO1 (rs1800566), GSTP1 I105V, GSTM1, GSTT1 (deletion vs. nondeletion), and HMOX-1 (any short vs. both long). We attempted to replicate identified genes in an analysis of heart rate variability and in other outcomes reported in the literature. METHODS: Study subjects were 1000 white non-Hispanic men in the Boston area, participating in a cohort study of aging. PM2.5, black carbon, total plasma homocysteine, and other covariates were measured at several points in time between 1995 and 2006. We fit mixed models to examine effect modification of genes on associations of pollution with total plasma homocysteine. RESULTS: Interquartile range increases in PM2.5 and black carbon (7-day moving averages) were associated with 1.5% (95% confidence interval = 0.2% to 2.8%) and 2.2% (0.6% to 3.9%) increases in total plasma homocysteine, respectively. GSTT1 and HFE C282Y modified effects of black carbon on total plasma homocysteine, and HFE C282Y and CAT (rs2300181) modified effects of PM2.5 on homocysteine. Several genotypes marginally modified effects of PM2.5 and black carbon on various endpoints. All genes with significant interactions with particulate air pollution had modest main effects on total plasma homocysteine. CONCLUSIONS:: Effects of PM2.5 and black carbon on various endpoints appeared to be mediated by genes related to oxidative stress pathways