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.

Mendelian Randomization and the Environmental Epigenetics of Health: a Systematic Review.

PURPOSE OF REVIEW: Epigenetic modifications are environmentally responsive and may play a mechanistic role in the development of disease. Mendelian randomization uses genetic variation to assess the causal effect of modifiable exposures on health outcomes. We conducted a systematic review of Mendelian randomization studies evaluating the causal role of DNA methylation (DNAm) changes on the development of health states, emphasizing on studies that formally evaluate exposure-DNAm, in addition to DNAm-outcome, causal associations. RECENT FINDINGS: We identified 15 articles, 4 of them including an environmental determinant of DNAm, including self-reported tobacco smoke exposure, in utero tobacco smoke exposure, measured vitamin B12, and glycemia. Selected articles suggest a causal association of DNAm with some cardiometabolic endpoints. DNAm seemed to partly explain the association of postnatal and prenatal exposure to tobacco smoke and vitamin B12 with inflammation biomarkers, birth weight, and cognitive outcomes, respectively. However, the current evidence is not sufficient to infer causality. Additional Mendelian randomization studies from large epidemiologic samples are needed to support the causal role of environmental factors as determinants of health-related epigenetic modifications.

Association of Methylation Signals With Incident Coronary Heart Disease in an Epigenome-Wide Assessment of Circulating Tumor Necrosis Factor α.

Importance: Tumor necrosis factor α (TNF-α) is a proinflammatory cytokine with manifold consequences for mammalian pathophysiology, including cardiovascular disease. A deeper understanding of TNF-α biology may enhance treatment precision. Objective: To conduct an epigenome-wide analysis of blood-derived DNA methylation and TNF-α levels and to assess the clinical relevance of findings. Design, Setting, and Participants: This meta-analysis assessed epigenome-wide associations in circulating TNF-α concentrations from 5 cohort studies and 1 interventional trial, with replication in 3 additional cohort studies. Follow-up analyses investigated associations of identified methylation loci with gene expression and incident coronary heart disease; this meta-analysis included 11 461 participants who experienced 1895 coronary events. Exposures: Circulating TNF-α concentration. Main Outcomes and Measures: DNA methylation at approximately 450 000 loci, neighboring DNA sequence variation, gene expression, and incident coronary heart disease. Results: The discovery cohort included 4794 participants, and the replication study included 816 participants (overall mean [SD] age, 60.7 [8.5] years). In the discovery stage, circulating TNF-α levels were associated with methylation of 7 cytosine-phosphate-guanine (CpG) sites, 3 of which were located in or near DTX3L-PARP9 at cg00959259 (ß [SE] = -0.01 [0.003]; P = 7.36 × 10-8), cg08122652 (ß [SE] = -0.008 [0.002]; P = 2.24 × 10-7), and cg22930808(ß [SE] = -0.01 [0.002]; P = 6.92 × 10-8); NLRC5 at cg16411857 (ß [SE] = -0.01 [0.002]; P = 2.14 × 10-13) and cg07839457 (ß [SE] = -0.02 [0.003]; P = 6.31 × 10-10); or ABO, at cg13683939 (ß [SE] = 0.04 [0.008]; P = 1.42 × 10-7) and cg24267699 (ß [SE] = -0.009 [0.002]; P = 1.67 × 10-7), after accounting for multiple testing. Of these, negative associations between TNF-α concentration and methylation of 2 loci in NLRC5 and 1 in DTX3L-14 PARP9 were replicated. Replicated TNF-α-linked CpG sites were associated with 9% to 19% decreased risk of incident coronary heart disease per 10% higher methylation per CpG site (cg16411857: hazard ratio [HR], 0.86; 95% CI, 0.78-1.95; P = .003; cg07839457: HR, 0.89; 95% CI, 0.80-0.94; P = 3.1 × 10-5; cg00959259: HR, 0.91; 95% CI, 0.84-0.97; P = .002; cg08122652: HR, 0.81; 95% CI, 0.74-0.89; P = 2.0 × 10-5). Conclusions and Relevance: We identified and replicated novel epigenetic correlates of circulating TNF-α concentration in blood samples and linked these loci to coronary heart disease risk, opening opportunities for validation and therapeutic applications.

Exposure to Low Levels of Lead in Utero and Umbilical Cord Blood DNA Methylation in Project Viva: An Epigenome-Wide Association Study.

BACKGROUND: Early-life exposure to lead is associated with deficits in neurodevelopment and with hematopoietic system toxicity. DNA methylation may be one of the underlying mechanisms for the adverse effects of prenatal lead on the offspring, but epigenome-wide methylation data for low levels of prenatal lead exposure are lacking. OBJECTIVES: We investigated the association between prenatal maternal lead exposure and epigenome-wide DNA methylation in umbilical cord blood nucleated cells in Project Viva, a prospective U.S.-based prebirth cohort with relatively low levels of lead exposure. METHODS: Among 268 mother-infant pairs, we measured lead concentrations in red blood cells (RBC) from prenatal maternal blood samples, and using HumanMethylation450 Bead Chips, we measured genome-wide methylation levels at 482,397 CpG loci in umbilical cord blood and retained 394,460 loci after quality control. After adjustment for batch effects, cell types, and covariates, we used robust linear regression models to examine associations of prenatal lead exposure with DNA methylation in cord blood at epigenome-wide significance level [false discovery rate (FDR)<0.05]. RESULTS: The mean [standard deviation (SD)] maternal RBC lead level was 1.22 (0.63) µg/dL. CpG cg10773601 showed an epigenome-wide significant negative association with prenatal lead exposure (-1.4% per doubling increase in lead exposure; p=2.3×10-7) and was annotated to C-Type Lectin Domain Family 11, Member A (CLEC11A), which functions as a growth factor for primitive hematopoietic progenitor cells. In sex-specific analyses, we identified more CpGs with FDR<0.05 among female infants (n=38) than among male infants (n=2). One CpG (cg24637308), which showed a strong negative association with prenatal lead exposure among female infants (-4.3% per doubling increase in lead exposure; p=1.1×10-06), was annotated to Dynein Heavy Chain Domain 1 gene (DNHD1) which is highly expressed in human brain. Interestingly, there were strong correlations between blood and brain methylation for CpG (cg24637308) based on another independent set of samples with a high proportion of female participants. CONCLUSION: Prenatal low-level lead exposure was associated with newborn DNA methylation, particularly in female infants. https://doi.org/10.1289/EHP1246.

Birth weight-for-gestational age is associated with DNA methylation at birth and in childhood.

BACKGROUND: Both higher and lower fetal growth are associated with cardio-metabolic health later in life, suggesting that prenatal developmental programming determines long-term cardiovascular disease risk. Epigenetic mechanisms, which orchestrate fetal growth and development, may offer insight on the early programming of health and disease. We investigated whether birth weight-for-gestational is associated with DNA methylation at birth and mid-childhood, measured via the Infinium 450K array. METHODS/RESULTS: Participants were from Project Viva, a pre-birth cohort of pregnant women and their children in Eastern Massachusetts. After exclusion of participants with maternal type 1 or 2 diabetes and gestational age <34 weeks, we used DNA methylation assays from 476 venous umbilical cord blood samples and a subset of 235 who additionally had peripheral blood samples available in mid-childhood (age 7-10 years). Among 392,918 CpG sites analyzed, birth weight-for-gestational age z-score was associated with cord blood DNA methylation at 34 CpGs (false discovery rate P < 0.05), after adjusting for maternal age, race/ethnicity, education, smoking, parity, delivery mode, pre-pregnancy BMI, gestational diabetes status, child sex, and estimated cord blood cell proportions based on a cord blood reference panel. Two of these CpGs were previously reported in epigenome-wide analyses of birth weight, and several other CpGs map to genes relevant to fetal growth and development. Namely, higher birth weight-for-gestational age was associated with higher methylation at four CpGs at the PBX1 locus (e.g., ß (95% CI) for lead signal at cg06750897 = 1.9 (1.2, 2.6)), which encodes a transcription factor that regulates embryonic development. Birth weight-for-gestational age was also associated with mid-childhood blood DNA methylation at four of the 34 CpGs identified in cord blood analyses, including sites at the PBX1 locus described. CONCLUSIONS: We identified CpG sites where birth weight-for-gestational age was associated with DNA methylation at birth, and for a subset of these sites, birth weight-for-gestational age was also associated with DNA methylation at mid-childhood.

Cardiovascular Health and Incident Cardiovascular Disease and Cancer: The Women's Health Initiative.

INTRODUCTION: The American Heart Association's "Simple 7" offers a practical public health conceptualization of cardiovascular health (CVH). CVH predicts incident cardiovascular disease (CVD) in younger populations, but has not been studied in a large, diverse population of aging postmenopausal women. The extent to which CVH predicts cancer in postmenopausal women is unknown. METHODS: Multivariable Cox regression estimated hazard ratios and 95% CIs for the association between CVH and incident CVD, any cancer, and cancer subtypes (lung, colorectal, and breast) among 161,809 Women's Health Initiative observational study and clinical trial participants followed from 1993 through 2010. Data were analyzed in 2013. CVH score was characterized as the number (0 [worst] to 7 [best]) of the American Heart Association's ideal CVH behaviors and factors at baseline: smoking, BMI, physical activity, diet, total cholesterol, blood pressure, and fasting glucose. RESULTS: Median follow-up was approximately 13 years. Fewer minorities and less educated women achieved ideal CVH, a common benchmark. In adjusted models, compared with women with the highest (best) CVH scores, those with the lowest (worst) CVH scores had nearly seven times the hazard of incident CVD (6.83, 95% CI=5.83, 8.00) and 52% greater risk of incident cancer (1.52, 95% CI=1.35, 1.72). Ideal CVH was most strongly inversely associated with lung cancer, then colorectal cancer, and then breast cancer. CONCLUSIONS: Lower ideal CVH is more common among minority and less educated postmenopausal women and predicts increased risk of CVD and cancer in this population, emphasizing the importance of prevention efforts among vulnerable older adults.

Adiposity is associated with DNA methylation profile in adipose tissue.

BACKGROUND: Adiposity is a risk factor for type 2 diabetes and cardiovascular disease, suggesting an important role for adipose tissue in the development of these conditions. The epigenetic underpinnings of adiposity are not well understood, and studies of DNA methylation in relation to adiposity have rarely focused on target adipose tissue. Objectives were to evaluate whether genome-wide DNA methylation profiles in subcutaneous adipose tissue and peripheral blood leukocytes are associated with measures of adiposity, including central fat mass, body fat distribution and body mass index. METHODS: Participants were 106 men and women (mean age 47 years) from the New England Family Study. DNA methylation was evaluated using the Infinium HumanMethylation450K BeadChip. Adiposity phenotypes included dual-energy X-ray absorptiometry-assessed android fat mass, android:gynoid fat ratio and trunk:limb fat ratio, as well as body mass index. RESULTS: Adipose tissue genome-wide DNA methylation profiles were associated with all four adiposity phenotypes, after adjusting for race, sex and current smoking (omnibus p-values <0.001). After further adjustment for adipose cell-mixture effects, associations with android fat mass, android:gynoid fat ratio, and trunk:limb fat ratio remained. In gene-specific analyses, adiposity phenotypes were associated with adipose tissue DNA methylation in several genes that are biologically relevant to the development of adiposity, such as AOC3, LIPE, SOD3, AQP7 and CETP. Blood DNA methylation profiles were not associated with adiposity, before or after adjustment for blood leukocyte cell mixture effects. CONCLUSION: Findings show that DNA methylation patterns in adipose tissue are associated with adiposity.

Healthy lifestyle and decreasing risk of heart failure in women: the Women's Health Initiative observational study.

BACKGROUND: The impact of a healthy lifestyle on risk of heart failure (HF) is not well known. OBJECTIVES: The objectives of this study were to evaluate the effect of a combination of lifestyle factors on incident HF and to further investigate whether weighting each lifestyle factor has additional impact. METHODS: Participants were 84,537 post-menopausal women from the WHI (Women's Health Initiative) observational study, free of self-reported HF at baseline. A healthy lifestyle score (HL score) was created wherein women received 1 point for each healthy criterion met: high-scoring Alternative Healthy Eating Index, physically active, healthy body mass index, and currently not smoking. A weighted score (wHL score) was also created in which each lifestyle factor was weighted according to its independent magnitude of effect on HF. The incidence of hospitalized HF was determined by trained adjudicators using standardized methodology. RESULTS: There were 1,826 HF cases over a mean follow-up of 11 years. HL score was strongly associated with risk of HF (multivariable-adjusted hazard ratio [HR] [95% confidence interval (CI)] 0.49 [95% CI: 0.38 to 0.62], 0.36 [95% CI: 0.28 to 0.46], 0.24 [95% CI: 0.19 to 0.31], and 0.23 [95% CI: 0.17 to 0.30] for HL score of 1, 2, 3, and 4 vs. 0, respectively). The HL score and wHL score were similarly associated with HF risk (HR: 0.46 [95% CI: 0.41 to 0.52] for HL score; HR: 0.48 [95% CI: 0.42 to 0.55] for wHL score, comparing the highest tertile to the lowest). The HL score was also strongly associated with HF risk among women without antecedent coronary heart disease, diabetes, or hypertension. CONCLUSIONS: An increasingly healthy lifestyle was associated with decreasing HF risk among post-menopausal women, even in the absence of antecedent coronary heart disease, hypertension, and diabetes. Weighting the lifestyle factors had minimal impact.