Role of Paraoxonase 2 in Airway Epithelial Response to Oxidant Stress.
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2024-10
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Asthma is a widespread chronic lung disease characterized by airway inflammation and hyperresponsiveness. This airway inflammation is classified by either the presence (T2-high) or absence (T2-low) of high levels of eosinophils. Because most therapies for asthma target eosinophils and related pathways, treatment options for T2-low disease are limited. New pathophysiologic targets are needed. Oxidant stress is a common feature of T2-low disease. Airway epithelial expression of the antioxidant enzyme Paraoxonase 2 (PON2) is decreased in a well-recognized population of people with T2-low asthma and people with obesity and asthma. As a potential mechanism of increased oxidant stress, we measured the role of PON2 in lung oxidant responses using an environmentally relevant in vivo murine oxidant exposure (i.e., ozone) and in vitro studies with an immortalized human airway epithelial cell line BEAS-2B. Pon2-deficient (Pon2-/-) mice developed increased airway hyper-responsiveness compared to wild-type controls. Despite reduced alveolar macrophage influx, Pon2-/- mice exhibited increased nitrite production. In human airway epithelial cells incubated with hydrogen peroxide, PON2 knockdown (PON2KD) decreased mitochondrial function and inner mitochondrial membrane potential. These findings suggest that PON2 functions in defending against airway epithelial oxidant stress. Further studies are needed to elucidate the mechanisms linking PON2, oxidant stress, and asthma pathogenesis.
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McCravy, Matthew S, Zhonghui Yang, Jaime Cyphert-Daly, Zachary R Healy, Aaron V Vose, Haein R Kim, Julia KL Walker, Robert M Tighe, et al. (2024). Role of Paraoxonase 2 in Airway Epithelial Response to Oxidant Stress. Antioxidants (Basel, Switzerland), 13(11). p. 1333. 10.3390/antiox13111333 Retrieved from https://hdl.handle.net/10161/32526.
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Scholars@Duke
Matthew Scott McCravy
Julia K.L. Walker
Broadly, my research focuses on the role for G protein-coupled receptors in the pathophysiology of asthma. Asthma is a complex disease characterized by airway inflammation, hyperresponsiveness and remodeling. G protein-coupled receptors figure largely in the pathology and treatment of this disease. For example, beta-agonists, the rescue medication inhaled by asthmatics, act at airway smooth muscle beta2-adrenergic receptors (β2-AR) to relax the airways. However, excessive use of beta-agonists has been associated with clinical worsening of asthma control and increased mortality. β2-ARs can signal through two well characterized and independent signaling pathways; a G protein-dependent pathway and a beta-arrestin-dependent pathway. Previously we showed that mice lacking beta-arrestin-2 do not develop the symptoms of allergic airway inflammatory disease and that T cell and eosinophil migration to the lung is impaired in these mice. Similarly, others have shown that the asthma phenotype is significantly reduced in mice lacking global expression of β2-ARs. Thus, we hypothesize that the beta-arrestin-dependent signaling arm, downstream of the β2-AR, is responsible for promoting the asthma phenotype. The translational relevance of this work is high given that the determination of the signaling pathway that is utilized by β2-ARs can be influenced by the molecular signature of the agonist. Thus, our work could lead to the discovery of a β2-AR ligand that bronchodilates the airways without promoting asthma symptoms. In addition to transducing β2-AR-mediated signaling to promote asthma, we hypothesize that beta-arrestin-2 also mediates chemokine receptor signaling and thus, the inflammatory component of asthma. Chemokines, released in response to allergens, dictate the migration of immune cells to the lung in asthma and chemokine receptors are known to signal via both the G-dependent and beta-arrestin-dependent pathways.
Robert Matthew Tighe
The research focus of the Tighe laboratory is performing pulmonary basic-translational studies to define mechanisms of susceptibility to lung injury and disease. There are three principal focus areas. These include: 1) Identifying susceptibility factors and candidate pathways relevant to host biological responses to environmental pollutants such as ozone, woodsmoke and silica, 2) Defining protective and detrimental functions of lung macrophage subsets and their cross talk with the epithelium to regulate lung injury and repair, and 3) Determining the prognostic and theragnostic efficacy of 3D lung gas exchange imaging in pulmonary fibrosis using hyperpolarized 129Xenon MRI.
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Susceptibility Factors for Environmental Lung Disease: In NIH funded studies the Tighe lab has been performing fully translational studies of lung responses to ozone. These include cell, rodent and human exposure studies to define mechanisms of susceptibility to exposure. By carefully dissecting these links, we will gain insight into how environmental pollutants acutely induce respiratory symptoms and exacerbate chronic lung diseases. This can lead to targeted therapeutics and/or identify susceptible populations. This includes exploration of genetic factors and also other metabolic and immunologic factors.
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Pulmonary Macrophage Functions and Crosstalk with Lung Epithelial Cells: The central hypothesis of this line of research is that macrophages are key regulators of the biologic responses to environmental pollutants and the development of chronic lung disease. The Tighe laboratory has pioneered the identification of novel pulmonary macrophage subsets and has defined their function in lung injury and repair. In both published work and areas of active investigation, the Tighe lab has identified macrophage subsets with unique genetic programming and function after challenges with environmental exposures such as ozone, wood smoke and silica. Since macrophages have both detrimental and protective functions, identifying these subsets offers the opportunity to understand their unique programing and function. This could allow development of targeted therapeutics that take advantage of these functions, polarize the immune responses and alleviate respiratory disease. In addition, we are focused on macrophage and epithelial crosstalk and how their combined responses regulate lung injury and repair. These studies include omics approaches with single-cell RNA sequencing, proteomics and metabolomics and lung organoids to identify unique signals between macrophages and epithelial cells.
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Using Hyperpolarized 129Xenon MRI to Define Prognosis and Therapy Responses in Pulmonary Fibrosis: In industry funded studies, the Tighe lab is focused on using a novel image modality to assess prognosis and therapeutic responses in individuals with pulmonary fibrosis. Pulmonary fibrosis is a disorder of progressive scar formation in the lung that causes increased shortness of breath and persistent coughing, frequently leading to death from respiratory failure. Presently, there are limited modalities that can assess prognosis in pulmonary fibrosis and can determine which individuals are responding to therapies. To address this, the Tighe lab, in collaboration with Dr. Bastiaan Driehuys in the Department of Radiology, is using inhaled hyperpolarized 129Xenon gas MRI to define regional differences in lung gas exchange in individuals with pulmonary fibrosis. Our preliminary data suggest that baseline characteristics of 129Xenon MRI associate with pulmonary fibrosis prognosis. In addition, we observe changes in the 129Xenon MRI metrics following initiation of pulmonary fibrosis therapies. These initial observations are being confirmed in ongoing clinical trials.
Heath Gasier
Dr. Gasier is a physiologist and nutritionist. His research is focused on understanding how breathing altered PO2 impacts cell physiology in the lung, brain, and skeletal muscle. Emphasis is placed on mitochondrial quality control (dynamics, mitophagy, and biogenesis) and bioenergetics. He uses in vivo and in vitro models, and employs an array of methods (e.g., confocal and electron microscopy, Seahorse respiration, immunoblotting, RT-qPCR, ELISA’s, isotope tracers, and 10X genomics) for hypothesis testing. The goal of his research is to improve the operational capacity of divers and safety of hyperoxia in hyperbaric and critical care medicine. Dr. Gasier believes in a hands-on mentoring approach and individualized training plans based on mentee’s aspirations. He is committed to lifetime learning and contributing to knowledge advancement.
Jennifer Leigh Ingram
Dr. Ingram's research interests focus on the study of airway remodeling in human asthma. Proliferation, migration, and invasion of airway fibroblasts are key features of airway remodeling that contribute to diminished lung function over time. Dr. Ingram uses molecular biology approaches to define the effects of interleukin-13 (IL-13), a cytokine abundantly produced in the asthmatic airway, in the human airway fibroblast. She has identified important regulatory functions of several proteins prevalent in asthma that control fibroblast growth and pro-fibrotic growth factor production in response to IL-13. By understanding these pathways and their role in human asthma and the chronic effects of airway remodeling, novel treatment strategies may be developed.
Loretta Georgina Que
My research interests focus on studying the role of nitric oxide and related enzymes in the pathogenesis of lung disease, specifically that caused by nitrosative/oxidative stress. Proposed studies are performed in cell culture and applied to animal models of disease, then examined in human disease where relevant. It is our hope that by better understanding the role of NO and reactive nitrogen species in mediating inflammation, and regulating cell signaling, that we will not only help to unravel the basic mechanisms of NO related lung disease, but also provide a rationale for targeted therapeutic use of NO.
Key words: nitrosative defense, lung injury, nitric oxide
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