Short-term exposure to PM(2.5) and vanadium and changes in asthma gene DNA methylation and lung function decrements among urban children.

BACKGROUND: Both short and long-term exposure to traffic-related air pollutants have been associated with asthma and reduced lung function. We hypothesized that short-term indoor exposure to fine particulate matter <2.5 μm (PM(2.5)) and vanadium (V) would be associated with altered buccal cell DNA methylation of targeted asthma genes and decreased lung function among urban children in a nested subcohort of African American and Dominican children. METHODS: Six day integrated levels of air pollutants were measured from children's homes (age 9-14; n = 163), repeated 6 months later (n = 98). Buccal samples were collected repeatedly during visits. CpG promoter loci of asthma genes (i.e., interleukin 4 (IL4), interferon gamma (IFNγ), inducible nitric oxide synthase (NOS2A), arginase 2 (ARG2)) were pyrosequenced and lung function was assessed. RESULTS: Exposure to V, but not PM(2.5), was associated with lower DNA methylation of IL4 and IFNγ. In exploratory analyses, V levels were associated with lower methylation of the proinflammatory NOS2A-CpG(+5099) among asthmatic overweight or obese children but not nonasthmatics. Short-term exposure to PM(2.5), but not V, appeared associated with lower lung function (i.e., reduced z-scores for forced expiratory volume in one second (FEV(1), FEV(1)/ forced vital capacity [FEV(1)/FVC] and forced expiratory flow at 25-75% of FVC [FEF(25-75)]). CONCLUSIONS: Exposure to V was associated with altered DNA methylation of allergic and proinflammatory asthma genes implicated in air pollution related asthma. However, short-term exposure to PM(2.5,) but not V, appeared associated with decrements in lung function among urban children.