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McDaniel DK, Ringel-Scaia VM, Morrison HA, Coutermarsh-Ott S, Council-Troche M, Angle JW, Perry JB, Davis G, Leng W, Minarchick V, Yang Y, Chen B, Reece SW, Brown DA, Cecere TE, Brown JM, Gowdy KM, Hochella MF, Allen IC. Pulmonary Exposure to Magnéli Phase Titanium Suboxides Results in Significant Macrophage Abnormalities and Decreased Lung Function. Front Immunol 2019; 10:2714. [PMID: 31849940 PMCID: PMC6892980 DOI: 10.3389/fimmu.2019.02714] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 11/05/2019] [Indexed: 01/03/2023] Open
Abstract
Coal is one of the most abundant and economic sources for global energy production. However, the burning of coal is widely recognized as a significant contributor to atmospheric particulate matter linked to deleterious respiratory impacts. Recently, we have discovered that burning coal generates large quantities of otherwise rare Magnéli phase titanium suboxides from TiO2 minerals naturally present in coal. These nanoscale Magnéli phases are biologically active without photostimulation and toxic to airway epithelial cells in vitro and to zebrafish in vivo. Here, we sought to determine the clinical and physiological impact of pulmonary exposure to Magnéli phases using mice as mammalian model organisms. Mice were exposed to the most frequently found Magnéli phases, Ti6O11, at 100 parts per million (ppm) via intratracheal administration. Local and systemic titanium concentrations, lung pathology, and changes in airway mechanics were assessed. Additional mechanistic studies were conducted with primary bone marrow derived macrophages. Our results indicate that macrophages are the cell type most impacted by exposure to these nanoscale particles. Following phagocytosis, macrophages fail to properly eliminate Magnéli phases, resulting in increased oxidative stress, mitochondrial dysfunction, and ultimately apoptosis. In the lungs, these nanoparticles become concentrated in macrophages, resulting in a feedback loop of reactive oxygen species production, cell death, and the initiation of gene expression profiles consistent with lung injury within 6 weeks of exposure. Chronic exposure and accumulation of Magnéli phases ultimately results in significantly reduced lung function impacting airway resistance, compliance, and elastance. Together, these studies demonstrate that Magnéli phases are toxic in the mammalian airway and are likely a significant nanoscale environmental pollutant, especially in geographic regions where coal combustion is a major contributor to atmospheric particulate matter.
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Affiliation(s)
- Dylan K. McDaniel
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
| | - Veronica M. Ringel-Scaia
- Graduate Program in Translational Biology, Medicine and Health, Virginia Tech, Blacksburg, VA, United States
| | - Holly A. Morrison
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
| | - Sheryl Coutermarsh-Ott
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
| | - McAlister Council-Troche
- Analytical Research Laboratory, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
| | - Jonathan W. Angle
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA, United States
| | - Justin B. Perry
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, United States
| | - Grace Davis
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, United States
| | - Weinan Leng
- National Center for Earth and Environmental Nanotechnology Infrastructure, Virginia Tech, Blacksburg, VA, United States
| | - Valerie Minarchick
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical, Aurora, CO, United States
| | - Yi Yang
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, China
| | - Bo Chen
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Sky W. Reece
- Department of Pharmacology & Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - David A. Brown
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, United States
| | - Thomas E. Cecere
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
| | - Jared M. Brown
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical, Aurora, CO, United States
| | - Kymberly M. Gowdy
- Department of Pharmacology & Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | | | - Irving C. Allen
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
- Graduate Program in Translational Biology, Medicine and Health, Virginia Tech, Blacksburg, VA, United States
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