Heterogeneous
Oxidation Products of Fine Particulate
Isoprene Epoxydiol-Derived Methyltetrol Sulfates Increase Oxidative
Stress and Inflammatory Gene Responses in Human Lung Cells
posted on 2023-10-31, 18:00authored byFaria Khan, Yuzhi Chen, Hadley J. Hartwell, Jin Yan, Ying-Hsuan Lin, Anastasia Freedman, Zhenfa Zhang, Yue Zhang, Andrew T. Lambe, Barbara J. Turpin, Avram Gold, Andrew P. Ault, Rafal Szmigielski, Rebecca C. Fry, Jason D. Surratt
Hydroxyl radical (·OH)-initiated oxidation
of isoprene,
the most abundant nonmethane hydrocarbon in the atmosphere, is responsible
for substantial amounts of secondary organic aerosol (SOA) within
ambient fine particles. Fine particulate 2-methyltetrol sulfate diastereoisomers
(2-MTSs) are abundant SOA products formed via acid-catalyzed multiphase
chemistry of isoprene-derived epoxydiols with inorganic sulfate aerosols
under low-nitric oxide conditions. We recently demonstrated that heterogeneous ·OH oxidation of particulate 2-MTSs leads to the particle-phase
formation of multifunctional organosulfates (OSs). However, it remains
uncertain if atmospheric chemical aging of particulate 2-MTSs induces
toxic effects within human lung cells. We show that inhibitory concentration-50
(IC50) values decreased from exposure to fine particulate
2-MTSs that were heterogeneously aged for 0 to 22 days by ·OH, indicating increased particulate toxicity in BEAS-2B lung cells.
Lung cells further exhibited concentration-dependent modulation of
oxidative stress- and inflammatory-related gene expression. Principal
component analysis was carried out on the chemical mixtures and revealed
positive correlations between exposure to aged multifunctional OSs
and altered expression of targeted genes. Exposure to particulate
2-MTSs alone was associated with an altered expression of antireactive
oxygen species (ROS)-related genes (NQO-1, SOD-2, and CAT) indicative of a response to ROS in the
cells. Increased aging of particulate 2-MTSs by ·OH
exposure was associated with an increased expression of glutathione
pathway-related genes (GCLM and GCLC) and an anti-inflammatory gene (IL-10).