Asthma is a chronic disease, which is increasing in prevalence, and imposes a considerable burden on health care in the United States and in many regions around the world. The increasing rate of asthma diagnosis and the evolving knowledge that subsets of asthmatics respond differently to therapies, has led to the notion that a better approach to treatment may be found by matching clinical asthma phenotypes with specifically targeted biologic therapeutics. Eosinophils, usually present in relatively small numbers in healthy individuals, become predominant effector cells in asthma. Despite the well-documented presence of elevated levels of eosinophils in allergic asthma, the mechanisms regulating eosinophil apoptosis and resolution of allergic airways remain enigmatic. Surfactant protein (SP)-A, a protein secreted by resident lung cells, plays a critical role in host defense. Our preliminary findings show that SP-A interacts with eosinophils to repress degranulation and promote apoptosis. Genetic variants of SP-A exist in the population and may be associated with lung disease. We have found that specific SP-A variants are less effective at regulation of eosinophil activities. Therefore, we hypothesize that specific motifs within SP-A facilitate resolution of allergic airways inflammation by directly initiating eosinophil apoptosis through receptor recognition and specific signaling events. Furthermore, in the asthmatic lung, genetic variation of SP-A results in impaired eosinophil apoptosis and therefore persistent eosinophilic airways inflammation. We will test our hypothesis with three specific aims:
Aim 1) Determine the mechanisms by which SP-A induces eosinophil apoptosis, Aim 2) Determine the mechanisms by which SP-A allelic variants differentially mediate eosinophil apoptosis, Aim 3) Determine whether the SP-A genotype contributes to the clinical eosinophilic phenotype of asthma. Our research team is well poised to conduct these innovative studies in mouse and man that will incorporate the use of novel humanized SP-A transgenic mice, SP-A2 allelic variant peptide fragments and SP-A variant oligomers to test our hypotheses. We anticipate that our approach will define the molecular and functional interactions that occur between SP-A and eosinophils in regulating resolution of allergic airway responses. Consequently, we believe that the data generated from this application will provide the groundwork needed for surfactant protein-based therapies to treat individuals with eosinophil predominant asthma.

Public Health Relevance

Asthma is a chronic disease of the airways characterized by inflammation and obstruction. This proposal investigates the mechanism by which surfactant protein-A (SP-A) regulates eosinophil apoptosis, a previously unrecognized protective role of SP-A in asthma. By mediating eosinophil apoptosis, SP-A limits the accumulation and release of cytotoxic mediators associated with eosinophils, which can exacerbate asthma severity. Understanding how SP-A regulates inflammation will help us develop novel strategies to treat asthma.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL125602-05
Application #
9691970
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Lu, Jining
Project Start
2015-08-15
Project End
2021-04-30
Budget Start
2019-05-01
Budget End
2021-04-30
Support Year
5
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Arizona
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Dy, Alane Blythe C; Tanyaratsrisakul, Sasipa; Voelker, Dennis R et al. (2018) The Emerging Roles of Surfactant Protein-A in Asthma. J Clin Cell Immunol 9:
Ito, Yoko; Schaefer, Niccolette; Sanchez, Amelia et al. (2018) Toll-Interacting Protein, Tollip, Inhibits IL-13-Mediated Pulmonary Eosinophilic Inflammation in Mice. J Innate Immun 10:106-118
Lugogo, Njira; Francisco, Dave; Addison, Kenneth J et al. (2018) Obese asthmatic patients have decreased surfactant protein A levels: Mechanisms and implications. J Allergy Clin Immunol 141:918-926.e3
Kummarapurugu, Apparao B; Zheng, Shuo; Ledford, Julie et al. (2018) High-Mobility Group Box 1 Upregulates MUC5AC and MUC5B Expression in Primary Airway Epithelial Cells. Am J Respir Cell Mol Biol 58:126-128
Addison, Kenneth J; Morse, John; Robichaud, Annette et al. (2017) A Novelin vivoSystem to Test Bronchodilators. J Infect Pulm Dis 3:
Noutsios, George T; Willis, Amanda L; Ledford, Julie G et al. (2017) Novel role of surfactant protein A in bacterial sinusitis. Int Forum Allergy Rhinol 7:897-903
Huang, C; Jiang, D; Francisco, D et al. (2016) Tollip SNP rs5743899 modulates human airway epithelial responses to rhinovirus infection. Clin Exp Allergy 46:1549-1563
Stein, Michelle M; Hrusch, Cara L; Gozdz, Justyna et al. (2016) Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children. N Engl J Med 375:411-421
Ledford, Julie G; Voelker, Dennis R; Addison, Kenneth J et al. (2015) Genetic variation in SP-A2 leads to differential binding to Mycoplasma pneumoniae membranes and regulation of host responses. J Immunol 194:6123-32