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DNA Methylation of the Aryl Hydrocarbon Receptor Repressor Associations With Cigarette Smoking and Subclinical Atherosclerosis.

ABSTRACT: BACKGROUND:Tobacco smoke contains numerous agonists of the aryl hydrocarbon receptor (AhR) pathway, and activation of the AhR pathway was shown to promote atherosclerosis in mice. Intriguingly, cigarette smoking is most strongly and robustly associated with DNA modifications to an AhR pathway gene, the AhR repressor (AHRR). We hypothesized that altered AHRR methylation in monocytes, a cell type sensitive to cigarette smoking and involved in atherogenesis, may be a part of the biological link between cigarette smoking and atherosclerosis. METHODS AND RESULTS:DNA methylation profiles of AHRR in monocytes (542 CpG sites ± 150 kb of AHRR, using Illumina 450K array) were integrated with smoking habits and ultrasound-measured carotid plaque scores from 1256 participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Methylation of cg05575921 significantly associated (P=6.1 × 10(-134)) with smoking status (current versus never). Novel associations between cg05575921 methylation and carotid plaque scores (P=3.1 × 10(-10)) were identified, which remained significant in current and former smokers even after adjusting for self-reported smoking habits, urinary cotinine, and well-known cardiovascular disease risk factors. This association replicated in an independent cohort using hepatic DNA (n=141). Functionally, cg05575921 was located in a predicted gene expression regulatory element (enhancer) and had methylation correlated with AHRR mRNA profiles (P=1.4 × 10(-17)) obtained from RNA sequencing conducted on a subset (n=373) of the samples. CONCLUSIONS:These findings suggest that AHRR methylation may be functionally related to AHRR expression in monocytes and represents a potential biomarker of subclinical atherosclerosis in smokers.

SUBMITTER: Reynolds LM

PROVIDER: S-EPMC4618776 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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DNA Methylation of the Aryl Hydrocarbon Receptor Repressor Associations With Cigarette Smoking and Subclinical Atherosclerosis.

Reynolds Lindsay M LM Wan Ma M Ding Jingzhong J Taylor Jackson R JR Lohman Kurt K Su Dan D Bennett Brian D BD Porter Devin K DK Gimple Ryan R Pittman Gary S GS Wang Xuting X Howard Timothy D TD Siscovick David D Psaty Bruce M BM Shea Steven S Burke Gregory L GL Jacobs David R DR Rich Stephen S SS Hixson James E JE Stein James H JH Stunnenberg Hendrik H Barr R Graham RG Kaufman Joel D JD Post Wendy S WS Hoeschele Ina I Herrington David M DM Bell Douglas A DA Liu Yongmei Y

Circulation. Cardiovascular genetics 20150825 5

<h4>Background</h4>Tobacco smoke contains numerous agonists of the aryl hydrocarbon receptor (AhR) pathway, and activation of the AhR pathway was shown to promote atherosclerosis in mice. Intriguingly, cigarette smoking is most strongly and robustly associated with DNA modifications to an AhR pathway gene, the AhR repressor (AHRR). We hypothesized that altered AHRR methylation in monocytes, a cell type sensitive to cigarette smoking and involved in atherogenesis, may be a part of the biological ...[more]

PMID: 26307030

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Project description:Introduction:Cigarette smoking is inversely associated with DNA methylation of the aryl hydrocarbon receptor repressor (AHRR; cg05575921). However, the association between secondhand tobacco smoke (SHS) exposure and AHRR methylation is unknown. Methods:DNA methylation of AHRR cg05575921 in CD14+ monocyte samples, from 495 never-smokers and 411 former smokers (having quit smoking ?15 years) from the Multi-Ethnic Study of Atherosclerosis (MESA), was cross-sectionally compared with concomitantly ascertained self-reported SHS exposure, urine cotinine concentrations, and estimates of air pollutants at participants' homes. Linear regression was used to test for associations, and covariates included age, sex, race, education, study site, and previous smoking exposure (smoking status, time since quitting, and pack-years). Results:Recent indoor SHS exposure (hours per week) was inversely associated with cg05575921 methylation (? ± SE = -0.009 ± 0.003, p = .007). The inverse effect direction was consistent (but did not reach significance) in the majority of stratified analyses (by smoking status, sex, and race). Categorical analysis revealed high levels of recent SHS exposure (?10 hours per week) inversely associated with cg05575921 methylation (? ± SE = -0.28 ± 0.09, p = .003), which remained significant (p < .05) in the majority of stratified analyses. cg05575921 methylation did not significantly (p < .05) associate with low to moderate levels of recent SHS exposure (1-9 hours per week), urine cotinine concentrations, years spent living with people smoking, years spent indoors (not at home) with people smoking, or estimated levels of air pollutants. Conclusions:High levels of recent indoor SHS exposure may be inversely associated with DNA methylation of AHRR in human monocytes. Implications:DNA methylation is a biochemical alteration that can occur in response to cigarette smoking; however, little is known about the effect of SHS on human DNA methylation. In the present study, we evaluated the association between SHS exposure and DNA methylation in human monocytes, at a site (AHRR cg05575921) known to have methylation inversely associated with current and former cigarette smoking compared to never smoking. Results from this study suggest high levels of recent SHS exposure inversely associate with DNA methylation of AHRR cg05575921 in monocytes from nonsmokers, albeit with weaker effects than active cigarette smoking.

Project description:There is a need to identify sensitive biomarkers of early tobacco-related cardiovascular disease. We examined the association of smoking status, burden, time since quitting, and intensity, with markers of inflammation and subclinical atherosclerosis. We studied 14 103 participants without clinical cardiovascular disease in ELSA-Brasil (Brazilian Longitudinal Study of Adult Health). We evaluated baseline cross-sectional associations between smoking parameters and inflammation (high-sensitivity C-reactive protein [hsCRP]) and measures of subclinical atherosclerosis (carotid intima-media thickness, ankle-brachial index, and coronary artery calcium [CAC]). The cohort included 1844 current smokers, 4121 former smokers, and 8138 never smokers. Mean age was 51.7±8.9 years; 44.8% were male. After multivariable adjustment, compared with never smokers, current smokers had significantly higher levels of hsCRP (β=0.24, 0.19-0.29 mg/L; P<0.001) and carotid intima-media thickness (β=0.03, 0.02-0.04 mm; P<0.001) and odds of ankle-brachial index ≤1.0 (odds ratio: 2.52; 95% confidence interval, 2.06-3.08; P<0.001) and CAC >0 (odds ratio: 1.83; 95% confidence interval, 1.46-2.30; P<0.001). Among former and current smokers, pack-years of smoking (burden) were significantly associated with hsCRP (P<0.001 and P=0.006, respectively) and CAC (P<0.001 and P=0.002, respectively). Among former smokers, hsCRP and carotid intima-media thickness levels and odds of ankle-brachial index ≤1.0 and CAC >0 were lower with increasing time since quitting (P<0.01). Among current smokers, number of cigarettes per day (intensity) was positively associated with hsCRP (P<0.001) and CAC >0 (P=0.03) after adjusting for duration of smoking. Strong associations were observed between smoking status, burden, and intensity with inflammation (hsCRP) and subclinical atherosclerosis (carotid intima-media thickness, ankle-brachial index, CAC). These markers of early cardiovascular disease injury may be used for the further study and regulation of traditional and novel tobacco products.

Project description:OBJECTIVES:To examine the contemporary effect of smoking in a multiethnic sample, and to explore the respective contributions of inflammation and subclinical atherosclerosis to the cardiovascular consequences of smoking. APPROACH AND RESULTS:We studied 6814 participants free of cardiovascular disease and coronary heart disease (CHD) from the Multiethnic Study of Atherosclerosis. Smoking status and cumulative exposure were determined by self-report and confirmed by urinary cotinine. Multivariable Cox regression was used to estimate the association between smoking parameters and all-cause cardiovascular disease, all-cause CHD, and hard CHD events. We further adjusted for high-sensitivity C-reactive protein and coronary artery calcium (CAC) in hierarchical Cox models. We identified 3218 never smokers, 2607 former smokers, and 971 current smokers. Median follow-up was 10.2 years. Compared with never smokers, adjusted hazard ratios in current smokers were 1.7 (95% confidence interval, 1.3-2.2) for all-cause cardiovascular disease, 1.6 (1.1-2.1) for all-cause CHD, and 1.7 (1.2-2.4) for hard CHD. Similarly, among current smokers, hazard ratios were higher in the 4th versus 1st quartile of pack-years (eg, all-cause CHD hazard ratio=2.7 [1.1-6.6]). Both CAC>100 and high-sensitivity C-reactive protein ?3 mg/L identified higher relative risk among current smokers (eg, all-cause CHD hazard ratio of 3.0 [1.5-6.0, compared with CAC=0] and 2.6 [1.4-4.8, compared with high-sensitivity C-reactive protein <2 mg/L], respectively). However, CAC was a stronger mediator of events and adversely modified the effect of smoking on events (eg, P-interaction=0.02 for hard CHD). Compared with never smokers, former smokers (median cessation interval=22 years) had similar adjusted hazard for events. CONCLUSIONS:In this multiethnic cohort, current smoking and cumulative exposure remain important modifiable determinants of cardiovascular disease. Both high-sensitivity C-reactive protein ?3 mg/L and, particularly, CAC>100 identified high-risk smokers who may benefit from more intensive smoking-cessation efforts.

Project description:OBJECTIVE:We sought to assess the impact of smoking status, cumulative pack-years, and time since cessation (the latter in former smokers only) on 3 important domains of cardiovascular disease: inflammation, vascular dynamics and function, and subclinical atherosclerosis. APPROACH AND RESULTS:The Multi-Ethnic Study of Atherosclerosis (MESA) cohort enrolled 6814 adults without prior cardiovascular disease. Smoking variables were determined by self-report and confirmed with urinary cotinine. We examined cross-sectional associations between smoking parameters and (1) inflammatory biomarkers (high-sensitivity C-reactive protein [hsCRP], interleukin-6, and fibrinogen); (2) vascular dynamics and function (brachial flow-mediated dilation and carotid distensibility by ultrasound, as well as aortic distensibility by MRI); and (3) subclinical atherosclerosis (coronary artery calcification, carotid intima-media thickness, and ankle-brachial index). We identified 3218 never smokers, 2607 former smokers, and 971 current smokers. Mean age was 62 years and 47% were male. There was no consistent association between smoking and vascular distensibility or flow-mediated dilation outcomes. However, compared with never smokers, the adjusted association between current smoking and measures of either inflammation or subclinical atherosclerosis was consistently stronger than for former smoking (eg, odds ratio for hsCRP>2 mg/L of 1.7 [95% confidence interval, 1.5-2.1] versus 1.2 [1.1-1.4], odds ratio for coronary artery calcification>0 of 1.8 [1.5-2.1] versus 1.4 [1.2-1.6], respectively). Similar associations were seen for interleukin-6, fibrinogen, carotid intima-media thickness, and ankle-brachial index. A monotonic association was also found between higher pack-year quartiles and increasing inflammatory markers. Furthermore, current smokers with hsCRP>2 mg/L were more likely to have increased carotid intima-media thickness, abnormal ankle-brachial index, and coronary artery calcification>75th percentile for age, sex, and race (relative to smokers with hsCRP<2 mg/L, interaction P<0.05 for all 3 outcomes). In contrast, time since quitting in former smokers was independently associated with lower inflammation and atherosclerosis (eg, odds ratio for hsCRP>2 mg/L of 0.91 [0.88-0.95] and odds ratio for coronary artery calcification>0 of 0.94 [0.90-0.97] for every 5-year cessation interval). CONCLUSIONS:These findings expand our understanding of the harmful effects of smoking and help explain the cardiovascular benefits of smoking cessation.

Dataset Information

DNA Methylation of the Aryl Hydrocarbon Receptor Repressor Associations With Cigarette Smoking and Subclinical Atherosclerosis.

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DNA Methylation of the Aryl Hydrocarbon Receptor Repressor Associations With Cigarette Smoking and Subclinical Atherosclerosis.

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