Evaluating the Impact of Metabolic Dysfunction on Asthma Pathology and Physiology

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Project Summary/Abstract: More than 40% of adult Americans are obese and obesity is common among patients with severe asthma. The mechanisms underlying the association between obesity and severe asthma are poorly understood, but a clue comes from the metabolic consequences of obesity, which include insulin resistance and systemic interleukin-6 inflammation. We recently showed that a subset of obese asthma patients have metabolic dysfunction (MD) and that obese patients with MD have more severe asthma than obese patients without MD. In addition, we found that lower lung function in obesity is more strongly related to measures of MD than measures of body mass index. Furthermore, we found that obese patients with MD respond poorly to inhaled and systemic corticosteroids. All of these findings lead us to hypothesize that obesity-related MD and insulin resistance causes airway pathology that leads to corticosteroid resistant airway dysfunction. Here, we propose to test this hypothesis by comprehensively characterizing airway physiology and pathology in obese asthma patients with MD and exploring mechanisms by which insulin mediates airway dysfunction. We have 3 aims: Aim 1 will characterize the radiographic and physiologic abnormalities in obese asthma patients with and without metabolic dysfunction (MD). Here we will analyze computed tomography lung scans and perform cardiopulmonary exercise testing in asthma patients with and without MD. We hypothesize that patients with MD have radiographic measures of bronchial wall thickness and air trapping and suffer dynamic hyperinflation during exercise leading to exercise intolerance. Aim 2 will characterize airway inflammation and airway remodeling in asthma patients with metabolic dysfunction; Here, we will map the cellular profile of asthma patients with MD using transcriptomic profiles from induced sputum samples and measure basement membrane zone thickness from endobronchial biopsy samples to test our hypothesis that airway inflammation in obese patients with MD is type-2 low and that these patients have airway remodeling characterized by subepithelial fibrosis. Aim 3 will develop gene signatures of insulin-related airway disease and determine if these signatures are upregulated in asthma patients with insulin resistance. Here we will utilize in vitro cell cultures and spatial transcriptomics to identify gene expression signatures of insulin-mediated airway disease in airway fibroblasts and epithelial cells. We will then determine if these gene signatures are upregulated in airway epithelial brushings or sputum cells from asthma patients with IR. Together these aims will help address an important gap in knowledge about disease mechanisms operating in obese patients with severe asthma and promises to provide data to inform novel treatment approaches for these patients.