Dose- and time-effect responses of DNA methylation and histone H3K9 acetylation changes induced by traffic-related air pollution

As an important risk factor of respiratory disorders, traffic-related air pollution (TRAP) has caused extensive concerns. Epigenetic change has been considered a link between TRAP and respiratory diseases. However, the exact effects of TRAP on epigenetic changes are still unclear. Here we investigated the dose-and time-effect responses of TRAP on DNA methylations and H3K9 acetylation (H3K9ac) in both blood and lung tissues of rats. The findings showed that every 1 mu g/m(3) increase of TRAP components were associated with changes in % 5 mC (95% CI) in LINE-1, iNOS, p16(CDKN2A), and APC ranging from -0.088% (-0.150, -0.026) to 0.102 (0.049, 0.154), as well as 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) ng/mg increase of H3K9ac. In addition, every 1 more day exposure at high level of TRAP (in tunnel) also significantly changed the levels of DNA methylation (ranging from -0.842% to 0.248%) and H3K9ac (16.033 and 15.718 ng/mg pro in PBMC and lung tissue, respectively) changes. Season and/or sex could interact with air pollutants in affecting DNA methylation and H3K9ac. The findings showed that TRAP exposure is dose-and time-dependently associated with the changes of DNA methylation and H3K9ac.