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Pitchai A, Buhman K, Shannahan JH. Lipid mediators of inhalation exposure-induced pulmonary toxicity and inflammation. Inhal Toxicol 2024; 36:57-74. [PMID: 38422051 PMCID: PMC11022128 DOI: 10.1080/08958378.2024.2318389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/07/2024] [Indexed: 03/02/2024]
Abstract
Many inhalation exposures induce pulmonary inflammation contributing to disease progression. Inflammatory processes are actively regulated via mediators including bioactive lipids. Bioactive lipids are potent signaling molecules involved in both pro-inflammatory and resolution processes through receptor interactions. The formation and clearance of lipid signaling mediators are controlled by multiple metabolic enzymes. An imbalance of these lipids can result in exacerbated and sustained inflammatory processes which may result in pulmonary damage and disease. Dysregulation of pulmonary bioactive lipids contribute to inflammation and pulmonary toxicity following exposures. For example, inhalation of cigarette smoke induces activation of pro-inflammatory bioactive lipids such as sphingolipids, and ceramides contributing to chronic obstructive pulmonary disease. Additionally, exposure to silver nanoparticles causes dysregulation of inflammatory resolution lipids. As inflammation is a common consequence resulting from inhaled exposures and a component of numerous diseases it represents a broadly applicable target for therapeutic intervention. With new appreciation for bioactive lipids, technological advances to reliably identify and quantify lipids have occurred. In this review, we will summarize, integrate, and discuss findings from recent studies investigating the impact of inhaled exposures on pro-inflammatory and resolution lipids within the lung and their contribution to disease. Throughout the review current knowledge gaps in our understanding of bioactive lipids and their contribution to pulmonary effects of inhaled exposures will be presented. New methods being employed to detect and quantify disruption of pulmonary lipid levels following inhalation exposures will be highlighted. Lastly, we will describe how lipid dysregulation could potentially be addressed by therapeutic strategies to address inflammation.
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Affiliation(s)
- Arjun Pitchai
- School of Health Sciences, College of Health and Human Sciences, Purdue University, West Lafayette, IN, United States
| | - Kimberly Buhman
- Department of Nutrition, College of Health and Human Sciences, Purdue University, West Lafayette, IN, United States
| | - Jonathan H. Shannahan
- School of Health Sciences, College of Health and Human Sciences, Purdue University, West Lafayette, IN, United States
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Ray JL, Postma B, Kendall RL, Ngo MD, Foo CX, Saunders B, Ronacher K, Gowdy KM, Holian A. Estrogen contributes to sex differences in M2a macrophages during multi-walled carbon nanotube-induced respiratory inflammation. FASEB J 2024; 38:e23350. [PMID: 38071600 PMCID: PMC10752389 DOI: 10.1096/fj.202301571rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023]
Abstract
Lung diseases characterized by type 2 inflammation are reported to occur with a female bias in prevalence/severity in both humans and mice. This includes previous work examining multi-walled carbon nanotube (MWCNT)-induced eosinophilic inflammation, in which a more exaggerated M2a phenotype was observed in female alveolar macrophages (AMs) compared to males. The mechanisms responsible for this sex difference in AM phenotype are still unclear, but estrogen receptor (ER) signaling is a likely contributor. Accordingly, male AMs downregulated ERα expression after MWCNT exposure while female AMs did not. Thus, ER antagonist Fulvestrant was administered prior to MWCNT instillation. In females, Fulvestrant significantly attenuated MWCNT-induced M2a gene expression and eosinophilia without affecting IL-33. In males, Fulvestrant did not affect eosinophil recruitment but reduced IL-33 and M2a genes compared to controls. Regulation of cholesterol efflux and oxysterol synthesis is a potential mechanism through which estrogen promotes the M2a phenotype. Levels of oxysterols 25-OHC and 7α,25-OHC were higher in the airways of MWCNT-exposed males compared to MWCNT-females, which corresponds with the lower IL-1β production and greater macrophage recruitment previously observed in males. Sex-based changes in cholesterol efflux transporters Abca1 and Abcg1 were also observed after MWCNT exposure with or without Fulvestrant. In vitro culture with estrogen decreased cellular cholesterol and increased the M2a response in female AMs, but did not affect cholesterol content in male AMs and reduced M2a polarization. These results reveal the modulation of (oxy)sterols as a potential mechanism through which estrogen signaling may regulate AM phenotype resulting in sex differences in downstream respiratory inflammation.
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Affiliation(s)
- Jessica L. Ray
- Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
| | - Britten Postma
- Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
| | - Rebekah L. Kendall
- Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
| | - Minh Dao Ngo
- Mater Research Institute, Translational Research Institute, The University of Queensland, Brisbane, Australia
| | - Cheng Xiang Foo
- Mater Research Institute, Translational Research Institute, The University of Queensland, Brisbane, Australia
| | - Brett Saunders
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Davis Heart and Lung Research Institute, Columbus, Ohio, USA
| | - Katharina Ronacher
- Mater Research Institute, Translational Research Institute, The University of Queensland, Brisbane, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Kymberly M. Gowdy
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Davis Heart and Lung Research Institute, Columbus, Ohio, USA
| | - Andrij Holian
- Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
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