Exogenous leptin enhances markers of airway fibrosis in a mouse model of chronic allergic airways disease.

Abstract

Background

Asthma patients with comorbid obesity exhibit increased disease severity, in part, due to airway remodeling, which is also observed in mouse models of asthma and obesity. A mediator of remodeling that is increased in obesity is leptin. We hypothesized that in a mouse model of allergic airways disease, mice receiving exogenous leptin would display increased airway inflammation and fibrosis.

Methods

Five-week-old male and female C57BL/6J mice were challenged with intranasal house dust mite (HDM) allergen or saline 5 days per week for 6 weeks (n = 6-9 per sex, per group). Following each HDM exposure, mice received subcutaneous recombinant human leptin or saline. At 48 h after the final HDM challenge, lung mechanics were evaluated and the mice were sacrificed. Bronchoalveolar lavage was performed and differential cell counts were determined. Lung tissue was stained with Masson's trichrome, periodic acid-Schiff, and hematoxylin and eosin stains. Mouse lung fibroblasts were cultured, and whole lung mRNA was isolated.

Results

Leptin did not affect mouse body weight, but HDM+leptin increased baseline blood glucose. In mixed-sex groups, leptin increased mouse lung fibroblast invasiveness and increased lung Col1a1 mRNA expression. Total lung resistance and tissue damping were increased with HDM+leptin treatment, but not leptin or HDM alone. Female mice exhibited enhanced airway responsiveness to methacholine with HDM+leptin treatment, while leptin alone decreased total respiratory system resistance in male mice.

Conclusions

In HDM-induced allergic airways disease, administration of exogenous leptin to mice enhanced lung resistance and increased markers of fibrosis, with differing effects between males and females.

Department

Description

Provenance

Citation

Published Version (Please cite this version)

10.1186/s12931-022-02048-z

Publication Info

Ihrie, Mark D, Victoria L McQuade, Jack T Womble, Akhil Hegde, Matthew S McCravy, Cyrus Victor G Lacuesta, Robert M Tighe, Loretta G Que, et al. (2022). Exogenous leptin enhances markers of airway fibrosis in a mouse model of chronic allergic airways disease. Respiratory research, 23(1). p. 131. 10.1186/s12931-022-02048-z Retrieved from https://hdl.handle.net/10161/25422.

This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.

Scholars@Duke

McCravy

Matthew Scott McCravy

Medical Instructor in the Department of Medicine
Tighe

Robert Matthew Tighe

Associate Professor of Medicine

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. 

  1. 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.

  2. 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. 

  3. 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.

Que

Loretta Georgina Que

Professor of Medicine

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

Walker

Julia K.L. Walker

Helene Fuld Health Trust Distinguished Professor of Nursing

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.


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