Mechanisms of Airway Epithelial Injury and Response

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ABSTRACT Cigarette smoking is the leading cause of chronic obstructive pulmonary disease (COPD); however, other exposures, such as occupational exposure to indoor pollution accounts for 20-25% of COPD cases in the United States. Exposure to organic dusts within swine confinement facilities (SCF) is a significant modifiable risk factor for lung disease in SCF workers. Numerous reports recognize the association between repetitive SCF organic dust exposure and development of a broad spectrum of chronic inflammatory lung diseases including chronic bronchitis (CB) – one of two major forms of COPD. However, the cellular and molecular mechanisms governing development of agriculture-related CB remain unclear. Challenges in the field of agriculture-related lung disease research include the difficulty in recreating SCF exposure conditions and the lack of physiologically relevant animal models to study `real world' exposures. Our preliminary data show that SCF pigs are a model for early airway epithelium injury and response, as evidenced by phenotypic lesions characteristic of CB including increased levels of the secreted airway mucins, airways contain goblet cell hyperplasia, inflammation, and evidence of smooth muscle hypertrophy compared to non-SCF (pasture) pigs. In this proposal, we will investigate mechanisms of airway epithelial injury and response to SCF organic dust by comparing the behavior of lung tissue from SCF and non-SCF pigs. To identify sources of inflammatory mediators, responses of lung leukocytes, lung slices and porcine tracheobronchial epithelial (PTBE) cells from SCF and non-SCF to endotoxin will be compared (Aim 1). The calcium/calmodulin-dependent protein kinase II (CaMKII), a kinase regulated by oxidative stress and implicated in pulmonary fibrosis, is more abundant in airway epithelial tissue of SCF pigs compared to non-SCF pigs. Therefore, studies using various inhibitors will be conducted to determine the role of CaMKII and oxidative stress in activation of airway inflammation pathways, including nuclear factor kappa B, using PTBE cells from SCF pigs (Aim 2). Given the observance of goblet cell hyperplasia in the airway epithelia of SCF pigs, we will utilize comprehensive proteomics approaches to identify molecular pathways associated with goblet cell hyperplasia in porcine models (Aim 3). Utilizing global and targeted proteomics approaches, pathways governing initiation and progression of goblet cell hyperplasia and mucus secretion will be identified. Knowledge of molecular pathways that regulate goblet cell hyperplasia will serve as potential targets for development of novel therapeutic strategies to treat CB affecting agricultural workers and the general population.