Ambient pollutants, polymorphisms associated with microRNA processing and adhesion molecules: the Normative Aging Study

Background: Particulate air pollution has been associated with cardiovascular morbidity and mortality, but it remains unclear which time windows and pollutant sources are most critical. MicroRNA (miRNA) is thought to be involved in cardiovascular regulation. However, little is known about whether polymorphisms in genes that process microRNAs influence response to pollutant exposure. We hypothesized that averaging times longer than routinely measured one or two day moving averages are associated with higher soluble intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) levels, and that stationary and mobile sources contribute differently to these effects. We also investigated whether single nucleotide polymorphisms (SNPs) in miRNA-processing genes modify these associations. Methods: sICAM-1 and sVCAM-1 were measured from 1999-2008 and matched to air pollution monitoring for fine particulate matter (PM(2.5)) black carbon, and sulfates (SO(4)(2-)). We selected 17 SNPs in five miRNA-processing genes. Mixed-effects models were used to assess effects of pollutants, SNPs, and interactions under recessive inheritance models using repeated measures. Results: 723 participants with 1652 observations and 1-5 visits were included in our analyses for black carbon and PM(2.5). Sulfate data was available for 672 participants with 1390 observations. An interquartile range change in seven day moving average of PM(2.5) (4.27 mu g/m(3)) was associated with 3.1% (95% CI: 1.6, 4.6) and 2.5% (95% CI: 0.6, 4.5) higher sICAM-1 and sVCAM-1. Interquartile range changes in sulfates (1.39 mu g/m(3)) were associated with 1.4% higher (95% CI: 0.04, 2.7) and 1.6% (95% CI: -0.4, 3.7) higher sICAM-1 and sVCAM-1 respectively. No significant associations were observed for black carbon. In interaction models with PM2.5, both sICAM-1 and sVCAM-1 levels were lower in rs1062923 homozygous carriers. These interactions remained significant after multiple comparisons adjustment. Conclusions: PM2.5 seven day moving averages are associated with higher sICAM-1 and sVCAM-1 levels. SO(4)(-2) seven day moving averages are associated with higher sICAM-1 and a suggestive association was observed with sVCAM-1 in aging men. SNPs in miRNA-processing genes may modify associations between ambient pollution and sICAM-1 and sVCAM-1, which are correlates of atherosclerosis and cardiovascular disease.