title: cAMP-dependent protein kinase activation decreases cytokine release in bronchial epithelial cells.
abstract: Lung injury caused by inhalation of dust from swine-concentrated animal-feeding operations (CAFO) involves the release of inflammatory cytokine interleukin 8 (IL-8), which is mediated by protein kinase C-ε (PKC-ε) in airway epithelial cells. Once activated by CAFO dust, PKC-ε is responsible for slowing cilia beating and reducing cell migration for wound repair. Conversely, the cAMP-dependent protein kinase (PKA) stimulates contrasting effects, such as increased cilia beating and an acceleration of cell migration for wound repair. We hypothesized that a bidirectional mechanism involving PKA and PKC regulates epithelial airway inflammatory responses. To test this hypothesis, primary human bronchial epithelial cells and BEAS-2B cells were treated with hog dust extract (HDE) in the presence or absence of cAMP. PKC-ε activity was significantly reduced in cells that were pretreated for 1 h with 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) before exposure to HDE (P < 0.05). HDE-induced IL-6, and IL-8 release was significantly lower in cells that were pretreated with 8-Br-cAMP (P < 0.05). To exclude exchange protein activated by cAMP (EPAC) involvement, cells were pretreated with either 8-Br-cAMP or 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (8-CPT-2Me-cAMP) (EPAC agonist). 8-CPT-2Me-cAMP did not activate PKA and did not reduce HDE-stimulated IL-6 release. In contrast, 8-Br-cAMP decreased HDE-stimulated tumor necrosis factor (TNF)-α-converting enzyme (TACE; ADAM-17) activity and subsequent TNF-α release (P < 0.001). 8-Br-cAMP also blocked HDE-stimulated IL-6 and keratinocyte-derived chemokine release in precision-cut mouse lung slices (P < 0.05). These data show bidirectional regulation of PKC-ε via a PKA-mediated inhibition of TACE activity resulting in reduced PKC-ε-mediated release of IL-6 and IL-8.
authors.affiliation: VA Nebraska-Western Iowa Health Care System Research Service, Department of Veterans Affairs Medical Center, Omaha, Nebraska; Department of Environmental, Agricultural, and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska; Pulmonary, Critical Care, Sleep and Allergy Division, Department of Internal Medicine, Nebraska Medical Center, Omaha, Nebraska twyatt@unmc.edu.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Wyatt
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, Department of Internal Medicine, Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Poole
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, Department of Internal Medicine, Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Tara M
authors.initials: TM
authors.lastname: Nordgren
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, Department of Internal Medicine, Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Jane M
authors.initials: JM
authors.lastname: DeVasure
authors.affiliation: Pulmonary, Critical Care, Sleep and Allergy Division, Department of Internal Medicine, Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Art J
authors.initials: AJ
authors.lastname: Heires
authors.affiliation: VA Nebraska-Western Iowa Health Care System Research Service, Department of Veterans Affairs Medical Center, Omaha, Nebraska; Department of Environmental, Agricultural, and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Kristina L
authors.initials: KL
authors.lastname: Bailey
authors.affiliation: VA Nebraska-Western Iowa Health Care System Research Service, Department of Veterans Affairs Medical Center, Omaha, Nebraska; Department of Environmental, Agricultural, and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska;
authors.forename: Debra J
authors.initials: DJ
authors.lastname: Romberger
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D051722:ADAM Proteins / Q000378:metabolism; D000072198:ADAM17 Protein; D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004391:Dust; D004797:Enzyme-Linked Immunosorbent Assay; D004917:Erythromycin / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D013552:Swine; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D004391:Dust; D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004917:Erythromycin; C057513:erythromycin propionate-N-acetylcysteinate; D017868:Cyclic AMP-Dependent Protein Kinases; D051744:Protein Kinase C-epsilon; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C000606463:Adam17 protein, mouse; D000111:Acetylcysteine
keywords: PKA; PKC-ε; cytokine; lung; organic dust