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Live Cell Imaging of Oxidative Stress in Human Airway Epithelial Cells Exposed to a Secondary Organic Aerosol
Citation:
Pennington, E., S. Masood, P. Bromberg, A. Gold, Z. Zhang, AND J. Samet. Live Cell Imaging of Oxidative Stress in Human Airway Epithelial Cells Exposed to a Secondary Organic Aerosol. Society of Toxicology Annual Meeting *VIRTUAL MEETING*, Chapel Hill, NC, March 12 - 22, 2021.
Impact/Purpose:
This is a poster presentation of an ongoing mechanistic investigation of the biochemical effects of a reactive environmental peroxide component of secondary aerosols using human airway epithelial cells.
Description:
Abstract: Isoprene hydroxy hydroperoxide (ISOPOOH) leads to the formation of secondary organic aerosols (SOA) generated from the reaction of vapor phase isoprene with atmospheric hydroxyl radical. This reaction is favored as anthropogenic air pollution levels have decreased in the atmosphere, limiting freely available NOX. Relatively little is known about the contribution of ISOPOOH in adverse human health effects from exposure to air pollution. However, previous studies have shown isoprene-derived SOA can induce inflammatory and oxidative gene expression in human airway epithelial cells (HAEC) and can lead to Nrf-2 activation. The objective of this study is to characterize the early mechanisms of oxidative stress induced by exposure of HAEC to non-cytotoxic concentrations of ISOPOOH. Our experimental approach relies on live-cell imaging of HAEC expressing roGFP, a genetically encoded fluorogenic sensors that specifically reports on changes in the glutathione redox potential (EGSH) dynamically. Exposure to micromolar concentrations of ISOPOOH induced glutathione oxidation in HAEC through a mechanism that is independent of the generation of extracellular and intracellular H2O2, suggesting lipid peroxidation of the plasma membrane and/or oxidation of glutathione through the involvement of glutathione peroxidases. Supplementation of HAEC with selenium potentiated the effect of ISOPOOH on EGSH, which implies glutathione peroxidase activity in transducing the peroxidative tone presented by ISOPOOH to the glutathione pool. Inhibition of glutaredoxin prior to ISOPOOH exposure completely ablated the EGSH response, demonstrating that roGFP is not directly oxidized but rather properly reports on ISOPOOH-induced EGSH changes. These findings show that ISOPOOH is a potent and unique environmental oxidant that likely contributes to the oxidative burden posed by exposure to SOA. THIS ABSTRACT OF A PROPOSED PRESENTATION DOES NOT NECESSARILY REFLECT EPA POLICY.