Biomarkers of Airway Inflammation and Oxidative Stress Regulated by Exposure to Swine Production Environments

摘要

Intensive swine production operations, primarily confinement-style housing, is known as a major source of air pollution. There is a substantial body of evidence reporting that swine confinement facility (SCF) organic dust can induce airway inflammation in healthy subjects that are acutely or chronically exposed to indoor facilities. However, the underlying mechanisms governing onset and persistence of agriculture related (ag-related) airway inflammation remains unclear. Oxidative stress, an imbalance between oxidants and antioxidant defenses within the body, is a result of free radicals or reactive oxygen species (ROS) binding to and altering functions of lipids, proteins or DNA. Chronic activity of ROS can lead to oxidative stress, inflammation and deregulation of important kinase signaling cascades. Therefore, these pathways represent plausible mechanisms by which respiratory diseases may develop in swine producers. Thus, the central hypothesis is pathway-specific proteomic analysis of tracheobronchial epithelia tissue of pigs reared indoors and outdoors will identify proteins that will serve as potential biomarkers of ag-related COPD in humans.;The central hypothesis was evaluated by performing cellular stress and kinase signaling proteome arrays and mass spectrometry-based kinome analysis of tracheobronchial epithelial tissue from indoor and outdoor reared pigs. Protein expression and activity levels were validated using western blots and protein activity assays, respectively. Normal human and pig tracheobronchial epithelia cells were exposed to a SCF organic dust extract in vitro and evaluated for modulation of kinase signaling, oxidative stress and inflammation as an extension of ex vivo pig airway tissue studies. Results revealed that, compared to outdoor pigs, airway epithelia of indoor pigs expressed higher basal levels of kinases (e.g. Calcium/Calmodulin-dependent protein kinase II, CaMKII), cell stress/inflammation (e.g., COX-2) and signal transduction (e.g., phospho-JNK) proteins that have been implicated in respiratory diseases. Inhibition of COX-2 diminished signs of inflammation and oxidative stress in human cells exposed to DE compared to unexposed cells.;These observations suggest that persistent exposure to indoor swine production environments modulates kinase signaling, oxidative stress and inflammation pathways in pig airways. More studies are needed to fully characterize biomarkers identified here for development of diagnostic and/or prognostic markers of respiratory diseases associated with swine production.