Rapid DNA Methylation Changes after Exposure to Traffic Particles

• Published in: American journal of respiratory and critical care medicine Vol. 179; no. 7; pp. 572 - 578
• Main Authors: Baccarelli, Andrea, Wright, Robert O, Bollati, Valentina, Tarantini, Letizia, Litonjua, Augusto A, Suh, Helen H, Zanobetti, Antonella, Sparrow, David, Vokonas, Pantel S, Schwartz, Joel
• Format: Journal Article
• Language: English
• Published: New York, NY Am Thoracic Soc 01.04.2009; American Thoracic Society
• Subjects: Aged; Aged, 80 and over; Aging; Air pollution; Alu Elements - drug effects; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Atherosclerosis; Biological and medical sciences; Carbon; Cardiovascular disease; D. Environmental and Occupational Lung Disease; DNA methylation; DNA Methylation - drug effects; Epigenesis, Genetic; Epigenetics; Genomes; Humans; Inhalation Exposure - adverse effects; Intensive care medicine; Investigative techniques, diagnostic techniques (general aspects); Long Interspersed Nucleotide Elements - drug effects; Male; Medical sciences; Middle Aged; Miscellaneous. Technology; Outdoor air quality; Oxidative stress; Particulate Matter - adverse effects; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Pollutants; Polymerase chain reaction; Prospective Studies; Seasons; Statistical analysis; Urban Population; Vehicle Emissions - toxicity; USA, Massachusetts, Boston; Intensive care; interspersed repetitive sequences; inhalation exposure; epigenetic processes; air pollution; Methylation; Resuscitation; Inhalation
• ISSN: 1073-449X; 1535-4970; 1535-4970
• DOI: 10.1164/rccm.200807-1097OC

Exposure to particulate air pollution has been related to increased hospitalization and death, particularly from cardiovascular disease. Lower blood DNA methylation content is found in processes related to cardiovascular outcomes, such as oxidative stress, aging, and atherosclerosis. We evaluated whether particulate pollution modifies DNA methylation in heavily methylated sequences with high representation throughout the human genome. We measured DNA methylation of long interspersed nucleotide element (LINE)-1 and Alu repetitive elements by quantitative polymerase chain reaction-pyrosequencing of 1,097 blood samples from 718 elderly participants in the Boston area Normative Aging Study. We used covariate-adjusted mixed models to account for within-subject correlation in repeated measures. We estimated the effects on DNA methylation of ambient particulate pollutants (black carbon, particulate matter with aerodynamic diameter < or = 2.5 microm [PM2.5], or sulfate) in multiple time windows (4 h to 7 d) before the examination. We estimated standardized regression coefficients (beta) expressing the fraction of a standard deviation change in DNA methylation associated with a standard deviation increase in exposure. Repetitive element DNA methylation varied in association with time-related variables, such as day of the week and season. LINE-1 methylation decreased after recent exposure to higher black carbon (beta = -0.11; 95% confidence interval [CI], -0.18 to -0.04; P = 0.002) and PM2.5 (beta = -0.13; 95% CI, -0.19 to -0.06; P < 0.001 for the 7-d moving average). In two-pollutant models, only black carbon, a tracer of traffic particles, was significantly associated with LINE-1 methylation (beta = -0.09; 95% CI, -0.17 to -0.01; P = 0.03). No association was found with Alu methylation (P > 0.12). We found decreased repeated-element methylation after exposure to traffic particles. Whether decreased methylation mediates exposure-related health effects remains to be determined.