title: Proteases in agricultural dust induce lung inflammation through PAR-1 and PAR-2 activation.
abstract: Workers exposed to aerosolized dust present in concentrated animal feeding operations (CAFOs) are susceptible to inflammatory lung diseases, such as chronic obstructive pulmonary disease. Extracts of dust collected from hog CAFOs [hog dust extract (HDE)] are potent stimulators of lung inflammatory responses in several model systems. The observation that HDE contains active proteases prompted the present study, which evaluated the role of CAFO dust proteases in lung inflammatory processes and tested whether protease-activated receptors (PARs) are involved in the signaling pathway for these events. We hypothesized that the damaging proinflammatory effect of HDE is due, in part, to the proteolytic activation of PARs, and inhibiting the proteases in HDE or disrupting PAR activation would attenuate HDE-mediated inflammatory indexes in bronchial epithelial cells (BECs), in mouse lung slices in vitro, and in a murine in vivo exposure model. Human BECs and mouse lung slice cultures stimulated with 5% HDE released significantly more of each of the cytokines measured (IL-6, IL-8, TNF-α, keratinocyte-derived chemokine/CXC chemokine ligand 1, and macrophage inflammatory protein-2/CXC chemokine ligand 2) than controls, and these effects were markedly diminished by protease inhibition. Inhibition of PARs also blunted the HDE-induced cytokine release from BECs. In addition, protease depletion inhibited HDE-induced BEC intracellular PKCα and PKCε activation. C57BL/6J mice administered 12.5% HDE intranasally, either once or daily for 3 wk, exhibited increased total cellular and neutrophil influx, bronchial alveolar fluid inflammatory cytokines, lung histopathology, and inflammatory scores compared with mice receiving protease-depleted HDE. These data suggest that proteases in dust from CAFOs are important mediators of lung inflammation, and these proteases and their receptors may provide novel targets for therapeutic intervention in CAFO dust-induced airways disease.
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska; Veterans Affairs Nebraska-Western Iowa Healthcare System, Omaha, Nebraska; dromberg@unmc.edu.
authors.forename: Debra J
authors.initials: DJ
authors.lastname: Romberger
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Art J
authors.initials: AJ
authors.lastname: Heires
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Tara M
authors.initials: TM
authors.lastname: Nordgren
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Chelsea P
authors.initials: CP
authors.lastname: Souder
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: William
authors.initials: W
authors.lastname: West
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Xiang-de
authors.initials: XD
authors.lastname: Liu
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Jill A
authors.initials: JA
authors.lastname: Poole
authors.affiliation: Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Myron L
authors.initials: ML
authors.lastname: Toews
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, University of Nebraska Medical Center, Omaha, Nebraska; Veterans Affairs Nebraska-Western Iowa Healthcare System, Omaha, Nebraska; Department of Environmental, Agricultural, and Occupational Health, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Wyatt
mesh_terms: D000382:Agricultural Workers' Diseases / Q000276:immunology*; D000395:Air Pollutants, Occupational / Q000276:immunology; D000821:Animal Feed; D000818:Animals; D001980:Bronchi / Q000473:pathology; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D004391:Dust / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008297:Male; D008810:Mice, Inbred C57BL; D016273:Occupational Exposure; D010447:Peptide Hydrolases / Q000276:immunology*; D011014:Pneumonia / Q000276:immunology*; D011493:Protein Kinase C / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000378:metabolism*; D044464:Receptor, PAR-2 / Q000378:metabolism*; D013552:Swine
chemical_list: D000395:Air Pollutants, Occupational; D016207:Cytokines; D004391:Dust; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D011493:Protein Kinase C; D010447:Peptide Hydrolases
keywords: environmental dust; epithelial cell; inflammation; lung; protease-activated receptors; proteases