Abstract 16656: DNA Methylation and mRNA Sequencing of Monocytes From a Large Cohort Identifies Associations Between an Epigenetic Biomarker of Smoking, AHRR Expression, and Atherosclerosis
Activation of the aryl-hydrocarbon receptor (AhR) promotes atherosclerosis in animal models and up-regulates the AhR repressor (AHRR). Intriguingly, the strongest and most robust epigenetic modifications reported in smokers are altered DNA methylation profiles of AHRR; however, the functional relevance of these modifications is unclear. Here we integrate AHRR methylation profiles of monocytes (542 CpG sites ± 150kb of AHRR, using Illumina 450K array) with smoking status and ultrasound measured carotid plaque levels from 1,264 participants of the Multi-Ethnic Study of Atherosclerosis (MESA), as well as cis-gene expression profiles (± 1MB, using RNA sequencing) in a subset (373) of the monocyte samples. Association analysis was adjusted for age, sex, race, study site, and residual sample contamination.
RESULTS: Current smoking was associated with methylation of 34 AHRR sites (false discovery rate, FDR<0.01), with hypomethylation of cg05575921 as the top signal (FDR=2.7x10-131) as previously reported. Over half (59%) of the smoking-associated methylation profiles also correlated with cis-gene expression (of AHRR, EXOC3, or C5orf55, FDR<0.01). However, only AHRR expression was strongly associated with current smoking (p=3.3x10-21). Of the 18 AHRR-associated CpG sites, cg05575921 was most strongly correlated with AHRR expression (corr: -0.42, FDR=4.3x10-15). Cg05575921 methylation profiles also significantly mediated (p=9.1x10-6) the association between current smoking and higher carotid plaque levels. The associations of cg05575921 methylation with smoking (p=0.002) and atherosclerosis (extended fatty streaks, p=0.002) replicated in hepatic biopsies of 141 males (PDAY study). Further characterizing this region, we identified seven CpG sites within 180bp (using RRBS) with methylation correlated with cg05575921, which overlap many predicted regulatory features (in ENCODE and BLUEPRINT monocyte data).
CONCLUSIONS: Integration of DNA methylation and RNA sequencing data from ex vivo monocytes revealed a link between the smoking-related methylation of AHRR, induction of AHRR expression, and atherosclerosis. These findings also provide evidence for involvement of the AhR signaling pathway in smoking-related atherogenesis.
Author Disclosures: L.M. Reynolds: None. M. Wan: None. J. Ding: None. J.R. Taylor: None. K. Lohman: None. R. Barr: None. T.D. Howard: None. D. Su: None. D. Porter: None. R. Gimple: None. G.S. Pittman: None. D. Siscovick: None. B.M. Psaty: None. S. Shea: None. D.R. Jacobs: None. S.S. Rich: None. J.E. Hixson: None. J.H. Stein: None. H.G. Stunnenberg: None. I. Hoeschele: None. D. Herrington: None. D.A. Bell: None. Y. Liu: None.
- © 2014 by American Heart Association, Inc.