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Liu F, Joo T, Ditto JC, Saavedra MG, Takeuchi M, Boris AJ, Yang Y, Weber RJ, Dillner AM, Gentner DR, Ng NL. Oxidized and Unsaturated: Key Organic Aerosol Traits Associated with Cellular Reactive Oxygen Species Production in the Southeastern United States. Environ Sci Technol 2023; 57:14150-14161. [PMID: 37699525 PMCID: PMC10538939 DOI: 10.1021/acs.est.3c03641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/14/2023]
Abstract
Exposure to ambient fine particulate matter (PM2.5) is associated with millions of premature deaths annually. Oxidative stress through overproduction of reactive oxygen species (ROS) is a possible mechanism for PM2.5-induced health effects. Organic aerosol (OA) is a dominant component of PM2.5 worldwide, yet its role in PM2.5 toxicity is poorly understood due to its chemical complexity. Here, through integrated cellular ROS measurements and detailed multi-instrument chemical characterization of PM in urban southeastern United States, we show that oxygenated OA (OOA), especially more-oxidized OOA, is the main OA type associated with cellular ROS production. We further reveal that highly unsaturated species containing carbon-oxygen double bonds and aromatic rings in OOA are major contributors to cellular ROS production. These results highlight the key chemical features of ambient OA driving its toxicity. As more-oxidized OOA is ubiquitous and abundant in the atmosphere, this emphasizes the need to understand its sources and chemical processing when formulating effective strategies to mitigate PM2.5 health impacts.
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Affiliation(s)
- Fobang Liu
- Department
of Environmental Science and Engineering, School of Energy and Power
Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Taekyu Joo
- School
of Earth and Atmospheric Sciences, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Jenna C. Ditto
- Department
of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States
| | - Maria G. Saavedra
- School
of Earth and Atmospheric Sciences, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Masayuki Takeuchi
- School of
Civil and Environmental Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Alexandra J. Boris
- Air
Quality Research Center, University of California
Davis, Davis, California 95618, United States
| | - Yuhan Yang
- School
of Earth and Atmospheric Sciences, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Rodney J. Weber
- School
of Earth and Atmospheric Sciences, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Ann M. Dillner
- Air
Quality Research Center, University of California
Davis, Davis, California 95618, United States
| | - Drew R. Gentner
- Department
of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States
| | - Nga L. Ng
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School
of Earth and Atmospheric Sciences, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
- School of
Civil and Environmental Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
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Liu F, Xu T, Ng NL, Lu H. Linking Cell Health and Reactive Oxygen Species from Secondary Organic Aerosols Exposure. Environ Sci Technol 2023; 57:1039-1048. [PMID: 36580374 DOI: 10.1021/acs.est.2c05171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Oxidative stress is a possible mechanism by which ambient fine particulate matter (PM) exerts adverse biological effects. While multiple biological effects and reactive oxygen species (ROS) production have been observed upon PM exposure, whether the biological effects are ROS-mediated remains unclear. Secondary organic aerosols (SOA) constitute a major fraction of fine PM and can contribute substantially to its toxicity. In this work, we measured three types of cell responses (mitochondrial membrane potential (MMP), caspase 3/7 activity, and ROS) and investigated their associations upon exposure to SOA formed from anthropogenic (naphthalene) and biogenic (α-pinene) precursors. MMP and caspase 3/7 activity (an early indicator of apoptosis) are key indicators of cell health, and changes of them could occur downstream of ROS-mediated pathways. We observed a significant increase in caspase 3/7 activity after SOA exposure, suggesting that apoptosis is an important pathway of cell death induced by SOA. We further found strong associations between a decrease in MMP and increase in caspase 3/7 activity with an increase in cellular ROS level. These results suggest that cell health is largely dependent on the cellular ROS level, highlighting oxidative stress as a key mechanism for biological effects from SOA exposure. Linear regression analyses reveal greater changes of the three cellular responses with increasing carbon oxidation state (OSc) of SOA, suggesting that SOA are more toxic when they are more oxidized. Overall, our work provides critical insights into the associations between cell health and ROS level upon SOA exposure and proposes that OSc could be a suitable proxy to assess the overall SOA toxicity.
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Affiliation(s)
- Fobang Liu
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi710049, China
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, Guangdong511443, China
| | - Tianchang Xu
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
| | - Nga Lee Ng
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
- School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia30332, United States
- School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
| | - Hang Lu
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
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