Obese asthmatic patients have decreased surfactant protein A levels: Mechanisms and implications.
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2018-03
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Abstract
Background
Eosinophils are prominent in some patients with asthma and are increased in the submucosa in a subgroup of obese patients with asthma (OAs). Surfactant protein A (SP-A) modulates host responses to infectious and environmental insults.Objective
We sought to determine whether SP-A levels are altered in OAs compared with a control group and to determine the implications of these alterations in SP-A levels in asthmatic patients.Methods
Bronchoalveolar lavage fluid from 23 lean, 12 overweight, and 20 obese subjects were examined for SP-A. Mouse tracheal epithelial cells grown at an air-liquid interface were used for mechanistic studies. SP-A-/- mice were challenged in allergen models, and exogenous SP-A therapy was given after the last challenge. Eosinophils were visualized and quantitated in lung parenchyma by means of immunostaining.Results
Significantly less SP-A (P = .002) was detected in samples from OAs compared with those from control subjects. A univariable regression model found SP-A levels were significantly negatively correlated with body mass index (r = -0.33, P = .014), whereas multivariable modeling demonstrated that the correlation depended both on asthma status (P = .017) and the interaction of asthma and body mass index (P = .008). Addition of exogenous TNF-α to mouse tracheal epithelial cells was sufficient to attenuate SP-A and eotaxin secretion. Allergen-challenged SP-A-/- mice that received SP-A therapy had significantly less tissue eosinophilia compared with mice receiving vehicle.Conclusions
SP-A functions as an important mediator in resolving tissue and lavage fluid eosinophilia in allergic mouse models. Decreased levels of SP-A in OAs, which could be due to increased local TNF-α levels, might lead to impaired eosinophil resolution and could contribute to the eosinophilic asthma phenotype.Type
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Lugogo, Njira, Dave Francisco, Kenneth J Addison, Akarsh Manne, William Pederson, Jennifer L Ingram, Cynthia L Green, Benjamin T Suratt, et al. (2018). Obese asthmatic patients have decreased surfactant protein A levels: Mechanisms and implications. The Journal of allergy and clinical immunology, 141(3). pp. 918–926.e3. 10.1016/j.jaci.2017.05.028 Retrieved from https://hdl.handle.net/10161/25433.
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Scholars@Duke
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.
Cynthia Lea Green
Survival Analysis
Longitudinal Data Analysis
Logistic Regression
Missing Data
Clinical Trial Methods
Maximum Likelihood Methods
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