DNA hypomethylation in association with internal and external markers of traffic exposure in a panel of healthy adults
Traffic-related air pollution (TRAP) exposure is associated with negative health outcomes. Changes in DNA methylation level may be an important mechanism through which air pollution can induce its effects. The objective of this study was to evaluate the association between DNA methylation in blood and personally measured TRAP exposure. Global DNA methylation in whole blood was analyzed with HPLC in a population of 55 healthy adults (average age 41 years). TRAP was assessed for each participant with a portable aethalometer measuring black carbon (BC). Exposure measurements were collected during one typical working week. These data were used in combination with ambient levels measured at a reference site to derive subchronic BC exposure. Urinary trans,trans-muconic acid (t,t-MA), a metabolite of benzene, was used as an internal proxy of traffic exposure. DNA methylation levels were associated with short- and subchronic BC exposure. An IQR increase in BC exposure on lag 24 h (477 ng/m3), lag 48 h (491 ng/m3), lag 1 week (314 ng/m3) and subchronic exposure (618 ng/m3) were associated with a decrease in DNA methylation levels of respectively 0.0020% (− 0.0040 to − 0.0001, p = 0.047), 0.0028% (− 0.0054 to − 0.0001, p = 0.043), 0.0024% (− 0.0043 to − 0.0005, p = 0.019), and 0.025% (− 0.048 to − 0.0015, p = 0.044). In addition, an IQR increase in t,t-MA (0.135 mg/l) was associated with a 0.0021% (− 0.0033 to − 0.0008, p = 0.0019) decrease in global DNA methylation levels. Analysis of a panel of cytokines in blood samples failed to demonstrate an association between inflammatory and oxidative stress biomarkers and TRAP or DNA methylation. In a panel of healthy adults, we found negative associations between total DNA methylation and markers of TRAP exposure. Considering that change in DNA methylation concentration is a biological marker connecting environmental and lifestyle exposures and disease development trajectories, our results warrant further study.
KeywordsAir pollution Traffic-related air pollution (TRAP) DNA methylation Black carbon t,t-Muconic acid
traffic-related air pollution
We thank the Flemish Environmental Agency for providing validated air quality data. The authors appreciate the nurses for their participation, patience, and support during the study.
LIP, PDB, TSN, and TL conceived the study. TL and EP performed field work. TL performed the laboratory analyses and statistics. GJ supported with her expertise on chemical analysis. TL, PDB and LIP interpreted the results. TL wrote first draft of the manuscript. All authors reviewed the manuscript and approved the final version.
Tijs Louwies was supported with a VITO PhD scholarship. Eline Provost was recipient of a VITO/FWO PhD scholarship. Tim S. Nawrot is holder of a European Research Council starting grant (ERC-2012-StG 310898).
Compliance with ethical standards
Ethics approval and consent to participate
The ethics boards of Hasselt University and University Hospital Antwerp approved the study.
Consent for publication
All participants provided written informed consent.
The authors declare they have no competing interests.
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