Identification of a dose of diesel exhaust particles that is sufficient to induce significant DNA methylation changes in A549 cells after four weeks of exposure.

Diesel exhaust particles (DEP), which contain hazardous compounds, are emitted during the combustion of diesel. As approximately one-third of the vehicles worldwide use diesel, there are growing concerns on the risks posed by DEP to human health. Long-term exposure to DEP is associated with airway hyperresponsiveness, pulmonary fibrosis, and inflammation; however, the molecular mechanisms behind the effects of DEP on the respiratory tract are poorly understood. Such mechanisms can be addressed by examining transcriptional and DNA methylation changes. In this study, we investigated DEP dose sufficient to induce significant DNA methylation changes after four weeks of exposure. A549 cells were treated with four doses of DEP (0, 3, 10 and 30 μg/ml ) for four weeks, using 2-3 biological replicates per group. The DNA methylation levels of 850K CpG sites were obtained for each treated group using the IInfinium MethylationEPIC BeadChips microarray. The sufficient dose of DEP was identified based on the results of differentially methylated analyses compared to the control