Dataset Information

Long-term ambient particle exposures and blood DNA methylation age: findings from the VA normative aging study.

ABSTRACT:

Background

Ambient particles have been shown to exacerbate measures of biological aging; yet, no studies have examined their relationships with DNA methylation age (DNAm-age), an epigenome-wide DNA methylation based predictor of chronological age.

Objective

We examined the relationship of DNAm-age with fine particulate matter (PM_2.5), a measure of total inhalable particle mass, and black carbon (BC), a measure of particles from vehicular traffic.

Methods

We used validated spatiotemporal models to generate 1-year PM_2.5 and BC exposure levels at the addresses of 589 older men participating in the VA Normative Aging Study with 1-3 visits between 2000 and 2011 (n = 1032 observations). Blood DNAm-age was calculated using 353 CpG sites from the Illumina HumanMethylation450 BeadChip. We estimated associations of PM_2.5 and BC with DNAm-age using linear mixed effects models adjusted for age, lifestyle/environmental factors, and aging-related diseases.

Results

After adjusting for covariates, a 1-µg/m³ increase in PM_2.5 (95% CI: 0.30, 0.75, P<0.0001) was significantly associated with a 0.52-year increase in DNAm-age. Adjusted BC models showed similar patterns of association (β = 3.02, 95% CI: 0.48, 5.57, P = 0.02). Only PM_2.5 (β = 0.54, 95% CI: 0.24, 0.84, P = 0.0004) remained significantly associated with DNAm-age in two-particle models. Methylation levels from 20 of the 353 CpGs contributing to DNAm-age were significantly associated with PM_2.5 levels in our two-particle models. Several of these CpGs mapped to genes implicated in lung pathologies including LZTFL1, PDLIM5, and ATPAF1.

Conclusion

Our results support an association of long-termambient particle levels with DNAm-age and suggest that DNAm-age is a biomarker of particle-related physiological processes.

SUBMITTER: Nwanaji-Enwerem JC

PROVIDER: S-EPMC4957520 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundSeveral epigenome-wide association studies (EWAS) of ambient particulate matter with aerodynamic diameter ≤ 2.5 µm (PM2.5) have been reported. However, EWAS of PM2.5 elements (PEs), reflecting different emission sources, are very limited.ObjectivesWe performed EWAS of short- and intermediate-term exposure to PM2.5 and 13 PEs. We hypothesized that significant changes in DNAm may vary by PM2.5 mass and its elements.MethodsWe repeatedly collected blood samples in the Normative Aging Study and measured leukocyte DNA methylation (DNAm) with the Illumina HumanMethylation450K BeadChip. We collected daily PM2.5 and 13 PEs at a fixed central site. To estimate the associations between each PE and DNAm at individual cytosine-phosphate-guanine (CpG) sites, we incorporated a distributed-lag (0-27 d) term in the setting of median regression with subject-specific intercept and examined cumulative lag associations. We also accounted for selection bias due to loss to follow-up and mortality prior to enrollment. Significantly differentially methylated probes (DMPs) were identified using Bonferroni correction for multiple testing. We further conducted regional and pathway analyses to identify significantly differentially methylated regions (DMRs) and pathways.ResultsWe included 695 men with 1,266 visits between 1999 and 2013. The subjects had a mean age of 75 years. The significant DMPs, DMRs, and pathways varied by to PM2.5 total mass and PEs. For example, PM2.5 total mass was associated with 2,717 DMPs and 10,470 DMRs whereas Pb was associated with 3,173 DMPs and 637 DMRs. The identified pathways by PM2.5 mass were mostly involved in mood disorders, neuroplasticity, immunity, and inflammation, whereas the pathways associated with motor vehicles (BC, Cu, Pb, and Zn) were related with cardiovascular disease and cancer (e.g., "PPARs signaling").ConclusionsPM2.5 and PE were associated with methylation changes at multiple probes and along multiple pathways, in ways that varied by particle components.