Significance of airway disease: Airway disease including asthma, chronic obstructive pulmonary disease, and cystic fibrosis are a significant cause of morbidity and mortality. A key feature of chronic inflammatory airway disease is hyper secretion of mucin proteins and airway obstruction by thick tenacious mucus. How the airway epithelial cell adapts to this stress of increased production and secretion of airway secretory mucins is not well understood. Autophagy as a novel pathway to regulate secretion: Autophagy, while highly conserved amongst eukaryotes, was previously thought to primarily regulate nutrient recycling in times of stress. It has now been established that autophagy is essential for multiple responses including protein secretion. Furthermore, autophagy appears to be particularly required during periods of high protein production and secretion during cellular stress. Our data just published in the Journal, Autophagy6, demonstrates that in the airway epithelia, autophagy is required for secretion of MUC5AC during Th2 inflammation. However, the mechanism of autophagy regulated mucin secretion in the airway is not known. Research Plan: In this application we present our preliminary data using in vitro human epithelial cells and in vivo mouse models of Th2 inflammation, demonstrating that autophagy is required for both MUC5Ac secretion and reactive oxygen species (ROS) generation. We hypothesize that these shared phenotypes are in fact connected and that autophagy-dependent ROS may be a novel mechanism that regulates secretion. To test this hypothesis, first, we will examine the role of calcium in autophagy-mediated basal and ATP-activated secretion of the secretory mucins, MUC5AC and MUC5B in the absence and presence of IL-13 using primary human airway epithelial cells (hTEC). Second, we will determine whether autophagy-dependent ROS regulates MUC5AC and or MUC5B independent of mucin production using hTEC. Third, we will examine the relationship among autophagy, ROS, and mucin secretion in an in vivo Th2 inflammation model using the autophagy deficient mice, Atg16l1HM/HM. This research application will advance our knowledge of airway biology using relevant models of human disease with the goal of identifying new therapeutic strategies. This work will advance through a structured program of career development with a goal of becoming an independent investigator. Career Development: As a physician-scientist, it is critically important to have strong mentorship from experienced investigators. My primary mentor, Dr. Joseph Sisson is fully committed to support my career goal of becoming an independent investigator in airway diseases. He has provided resources to establish my lab, protect my research time with limited clinical duties, so that I have begun work on experiments outlined above within the context of a career development plan. This plan includes oversight by experienced investigators on a formal mentorship committee to ensure that important career milestones are being met, formal course work, and development of new collaborations at the University of Nebraska and around the world.

Public Health Relevance

We propose that autophagy is a universal regulator of MUC5AC and MUC5B protein secretion. Chronic IL-13 activation, however, amplifies autophagy-mediated MUC5AC secretion though a mechanism involving intracellular ROS. We predict that IL-13 stimulated MUC5AC secretion can be reduced by targeting autophagy- dependent ROS, offering an avenue for future therapeutic strategies in airway diseases.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Clinical Investigator Award (CIA) (K08)
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NHLBI Mentored Clinical and Basic Science Review Committee (MCBS)
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Lu, Qing
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University of Nebraska Medical Center
Internal Medicine/Medicine
Schools of Medicine
United States
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Dickinson, John D; Sweeter, Jenea M; Warren, Kristi J et al. (2018) Autophagy regulates DUOX1 localization and superoxide production in airway epithelial cells during chronic IL-13 stimulation. Redox Biol 14:272-284
Dickinson, John D; Sweeter, Jenea M; Staab, Elizabeth B et al. (2018) MyD88 controls airway epithelial Muc5ac expression during TLR activation conditions from agricultural organic dust exposure. Am J Physiol Lung Cell Mol Physiol :
Warren, Kristi J; Sweeter, Jenea M; Pavlik, Jacqueline A et al. (2017) Sex differences in activation of lung-related type 2 innate lymphoid cells in experimental asthma. Ann Allergy Asthma Immunol 118:233-234
Hakim, Frances T; Memon, Sarfraz; Jin, Ping et al. (2016) Upregulation of IFN-Inducible and Damage-Response Pathways in Chronic Graft-versus-Host Disease. J Immunol 197:3490-3503