AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Dose-dependent Intracellular Reactive Oxygen and Nitrogen Species Production from Particulate Matter Exposure: Comparison to Oxidative Potential and Chemical Composition
WING-YIN TUET, Shierly Fok, Vishal Verma, Marlen Tagle Rodriguez, Anna Grosberg, Julie Champion, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 393 Working Group: Health Related Aerosols
Abstract Health effects of particulate matter (PM) exposure have received considerable attention wherein epidemiological studies have associated elevated PM concentrations with increases in the incidence of cardiopulmonary diseases. Toxicology studies have suggested that PM-induced oxidant production, including reactive oxygen and nitrogen species (ROS/RNS), may induce inflammatory cascades, which may in turn lead to further oxidative stress, cellular damage, and chronic inflammation. Here we present ROS/RNS measurements from 104 ambient PM samples collected from urban and rural sites during multiple seasons in the southeastern US as part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study. Murine alveolar macrophages and neonatal rat ventricular myocytes were used to measure intracellular PM-induced ROS/RNS production using a fluorescent probe, carboxy-H2DCFDA. For each filter sample, a dose-response curve was obtained over ten dilutions, and the Hill equation was applied to obtain response parameters (maximum response, EC50, Hill slope, threshold, and area under the dose-response curve, AUC). These parameters were then compared with results from a common chemical assay (dithiothreitol, DTT assay) to determine whether chemical assays represent cellular ROS/RNS response, and with water-soluble PM components to elucidate species associated with PM-induced ROS/RNS production. We found that ROS/RNS production was highly dose-dependent, non-linear, and could not be represented by a single concentration measurement. Furthermore, we demonstrate that no simple correlation exists between DTT activity/PM composition and cellular ROS/RNS responses. For summer samples, we found that DTT activity, water-soluble organic carbon, and brown carbon were significantly correlated with cellular ROS/RNS production as measured by AUC, which highlights the importance of understanding the contribution of summertime secondary organic aerosols (SOA) to PM-induced ROS/RNS production.