Microvesicle-associated microRNA expression is altered upon particulate matter exposure in healthy workers and in A549 cells

Cardiovascular disease risk has been consistently linked with particulate matter (PM) exposure. Cell-derived microvesicles (MVs) are released into plasma and transfer microRNAs (miRNAs) between tissues. MVs can be produced by the respiratory system in response to proinflammatory triggers, enter the circulatory system and remotely modify gene expression in cardiovascular tissues. However, whether PM affects MV signaling has never been investigated. In this study, we evaluated expression of microRNAs contained within plasma MVs upon PM exposure both in vivo and in vitro. In the in vivo study, we isolated plasma MVs from healthy steel plant workers before and after workplace PM exposure. We measured the expression of 88 MV-associated miRNAs by real-time polymerase chain reaction. To assess a possible source of the MV miRNAs identified in vivo, we measured their miRNA expression in PM-treated A549 pulmonary cell lines in vitro. MiRNA profiling of plasma MVs showed 5.62- and 13.95-fold increased expression of miR-128 and miR-302c, respectively, after 3 days of workplace PM exposure (P < 0.001). According to Ingenuity Pathway Analysis, miR-128 is part of coronary artery disease pathways, and miR-302c is part of coronary artery disease, cardiac hypertrophy and heart failure pathways. In vitro experiments confirmed a dose-dependent expression of miR-128 in MVs released from A549 cells after 6 h of PM treatment (P = 0.030). MiR-302c was expressed neither from A549 cells nor in reference lung RNA. These results suggest novel PM-activated molecular mechanisms that may mediate the effects of air pollution and could lead to the identification of new diagnostic and therapeutic interventions. Copyright © 2014 The Authors. Journal of Applied Toxicology Published by John Wiley & Sons Ltd. Cell-derived microvesicles (MVs) are found in plasma and may transfer signals between tissues. In this article, we report in-vivo and in-vitro studies demonstrating that Particulate Matter (PM) affects systemic MV signaling by inducing MV release from alveolar cells into plasma. In-vivo microRNA screening showed increased miR-128 level in plasma MVs after PM exposure. In-vitro experiments confirmed PM-induced release of miR-128 in MVs from A549 alveolar cells. Future studies are warranted to determine the roles of MVs in mediating PM effects.