Genomic DNA methylation signatures in different tissues after ambient air particulate matter exposure

DNA methylation (5-mc) is one of the several epigenetic markers, and is generally associated with the inhibition of gene expression. Both hyper and hypo DNA methylation are associated with the diseases. Exposure to fine particles with a diameter of 2.5 μm or less (PM_2.5) is a pervasive risk factor for cardiopulmonary mortality, metabolic disorders, cognition damage, and etc.. Recent reports pointed toward that these diseases were associated with the altered DNA methylation level of some specific-gene, potentially suggesting that the DNA methylation alteration was involved in the health hazard derived from the PM_2.5 exposure. In this study, we systematically investigated the global DNA methylation level of most tissues, including lung, heart, testis, thymus, spleen, epididymal fat, hippocampus, kidney, live, after short and long term PM_2.5 exposure. After acute PM_2.5 exposure, the global hypo-methylation in DNA was observed in lung and heart. Notably, after chronic PM_2.5 exposure, level of global DNA methylation decreased in most organs which included lung, testis, thymus, spleen, epididymal fat, hippocampus and blood. The present study systematically demonstrated the global DNA methylation changes by PM_2.5 exposure, and put forward a possible orientation for further exploring the effects of ambient air particles exposure on the specific organs.