A Macrophage-Based Method for the Assessment of the Reactive Oxygen Species (ROS) Activity of Atmospheric Particulate Matter (PM) and Application to Routine (Daily-24 h) Aerosol Monitoring Studies

Abstract

Both short-and long-term exposure to particulate matter (PM) air pollution have been demonstrated to cause increases in cardiovascular disease, cancer, and respiratory disorders. Although the specific mechanisms by which exposure to PM cause these affects are unclear, significant evidence has accumulated to suggest that PM exposure leads to increased inflammation as the result of excessive production of reactive oxygen species (ROS) in critical cell types. In order to better understand how real-world PM exposure causes adverse health effects, there is a need to efficiently integrate metrics of PM toxicity into large scale air monitoring and health effects/epidemiology studies. Here we describe a rapid, inexpensive, method that can be employed to assess the potential of sub-mg masses of PM to generate oxidative stress in alveolar macrophage cells. Importantly, the approach is compatible with routine daily PM sampling programs such as those administered by EPA (Speciation trends network (STN), IMPROVE network, PM2.5 mass monitoring network), allowing for multiple samples to be assessed simultaneously with low volumes and brief exposure periods. We apply the method to a set of water extracts of daily PM2.5 samples (25-350 µg PM mass) collected in the Denver-Metro area. Variations in the magnitude of the ROS response observed between the samples were only partially explained by differences in mass loading, with the highest levels of ROS being observed in samples collected during the summer months. This assay provides a very useful tool that can be coupled with detailed chemical analysis and statistical models to work towards the goal of attributing PM toxicity to specific real-world chemical sources.

Inflammatory responses to secondary organic aerosols (SOA) generated from biogenic and anthropogenic precursors

“…The antioxidant is oxidized via electron transfer reactions catalyzed by redox-active species in the PM sample, and its rate of decay serves as a measure of the concentration of redox-active species present . On the other hand, cellular assays utilize a fluorescent probe (e.g., carboxy-H 2 DCFDA) that reacts with ROS/RNS, and the measured fluorescence is proportional to the concentration of ROS/RNS produced as a result of PM exposure (Landreman et al, 2008;Tuet et al, 2016). Both types of assays have been utilized extensively to characterize a variety of PM samples and identify sources that may be detrimental to health Saffari et al, 2015;Fang et al, 2015a;Bates et al, 2015;Li et al, 2003b;Tuet et al, 2016).…”

“…Various assays have been developed to study PM-induced oxidant production, including cell-free chemical assays that measure the oxidative potential of PM samples (Kumagai et al, 2002;Cho et al, 2005;Fang et al, 2015b) as well as cellular assays that measure intracellular ROS/RNS produced as a result of PM exposure (Landreman et al, 2008;Tuet et al, 2016). Cell-free assays simulate biologically relevant redox (reduction-oxidation) reactions using an antioxidant species (e.g., dithiothreitol, DTT; ascorbic acid, AA).…”

Development and Evaluation of a High-Volume Aerosol-into-Liquid Collector for Fine and Ultrafine Particulate Matter

“…Daher et al (2011) compared sampling techniques of filtration, impaction, and VACES/BioSampler tandem, and an overall very good agreement in PM collection efficiency and chemical composition was observed among the different samplers. In contrast, dissimilarities in PM oxidative properties, measured by an ROS assay (Landreman et al 2008), were apparent between the BioSampler slurry and aqueous extracts of the filter and impactor samples, with the former technology measuring considerably higher ROS levels, whereas filtering the VACES/BioSampler slurries brought their ROS content to virtually identical levels to those of the impactor and filter. The higher reactive oxygen species (ROS) values of the VACES/BioSampler were thus attributed to potentially toxic insoluble PM species, which cannot be effectively extracted from filter or impactor substrates with water.…”

“…The macrophage ROS assay employed a fluorogenic cell-based method to investigate the production of ROS in rat alveolar macrophages (NR8383; American Type Culture Collection, Manassas, VA, USA) using 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA) as the fluorescent probe. Details of the assay, extraction protocol, and detection methodology are explained in previous study (Landreman et al 2008). All the analysis mentioned above was also performed on lab blanks, and all the chemical/ROS speciation data presented in this manuscript are blank corrected.…”

In vitro Evaluation of Oxidative Stress Caused by Fine Particles (PM2.5) Exhausted from Heavy-Duty Vehicles Using Diesel/Biodiesel Blends under Real World Conditions

“…24,25 For instance, some transition metals (such as Fe and Cu) and organic species (e.g. polycyclic aromatic compounds and quinones or quinone-like compounds) as well as humic-like substances (HULIS), black and brown carbon (BC and BrC) within PM are known to increase the production of ROS either in vitro or in vivo, especially if they are present in fine and ultrafine size range, [4][5][6]24,[30][31][32][33][34][35] since they are able to go more profoundly in the respiratory system. Meanwhile, considering diesel/biodiesel blends exhausts are substantially composed by ever small size PM, such as nanoparticles and/or ultrafine particles rich in semi-volatile organic compounds and trace metals, 1,7,16 it is likely ROS may be contributing to the adverse health effects caused by DEP or even BEP.…”