Effects of airborne particulate matter (PM_(10)) from dust storm and thermal inversion on global DNA methylation in human peripheral blood mononuclear cells (PBMCs) in vitro

摘要

Scientists have considered epigenetic modifications as a possible mechanism to deal with adverse effects of air pollution. This study aimed to compare the effect of PM10 (PM with aerodynamic diameter = 10 mu m) from dust storm and inversion conditions on in vitro global methylation in human peripheral blood mononuclear cells (PBMCs). PM10 was sampled in Tehran, Iran, at a point impacted with dust storm and inversion. PM toxicity was determined using the MTT assay. PBMCs were extracted from whole blood of healthy males and treated separately with a mixture of pooled PM(10 )from inversion and dusty conditions at concentrations of 50-300 mu g/mL for 4h. Untreated cells were used as the negative control. Moreover, 5-methylsytosine (%5-mC) and 5-hydroxymethylcytosine (%5-hmC) were measured by the enzyme-linked immunosorbent assay (ELISA) method. Daily average PM10 concentrations in dusty and inversion days were 348.40 and 220.54 mu g/m(3), respectively. The mean of %5-mC (2.04 +/- 1.49%) was estimated 12 times more than that of %5-hmC (0.17 +/- 0.11%). PM10, resulting from the both sources caused DNA hypomethylation; however, this effect from inversion (median = 3%, IQR = 2.4%) was found to be significantly more than that from dust storm (median = 1.1%, IQR = 1.38%). Moreover, particles increased %5-hmC caused by PM10, which was significantly greater when resulting from inversion (0.23 +/- 0.1%) than from dust storm (0.12 +/- 0.09%). Furthermore, %5-mC and %5-hmC were significantly different at different PM10 concentrations (50-300 mu g/mL) so that a significant difference was observed between %5-mC and %5-hmC at extreme concentrations. Results showed that PM10 from inversion caused a significantly more global methylation than that from dust storm. It can be concluded that measurement of 5-mC and 5-hmC as epigenetic modifications in environmental studies of DNA methylation can be a good procedure to determine health effects related to PM10 exposure.