title: Toll-Like Receptor 4 Engagement Mediates Prolyl Endopeptidase Release from Airway Epithelia via Exosomes.
abstract: Proteases are important regulators of pulmonary remodeling and airway inflammation. Recently, we have characterized the enzyme prolyl endopeptidase (PE), a serine peptidase, as a critical protease in the generation of the neutrophil chemoattractant tripeptide Pro-Gly-Pro (PGP) from collagen. However, PE has been characterized as a cytosolic enzyme, and the mechanism mediating PE release extracellularly remains unknown. We examined the role of exosomes derived from airway epithelia as a mechanism for PE release and the potential extracellular signals that regulate the release of these exosomes. We demonstrate a specific regulatory pathway of exosome release from airway epithelia and identify PE as novel exosome cargo. LPS stimulation of airway epithelial cells induces release of PE-containing exosomes, which is significantly attenuated by small interfering RNA depletion of Toll-like receptor 4 (TLR4). These differences were recapitulated upon intratracheal LPS administration in mice competent versus deficient for TLR4 signaling. Finally, sputum samples from subjects with cystic fibrosis colonized with Pseudomonas aeruginosa demonstrate elevated exosome content and increased PE levels. This TLR4-based mechanism highlights the first report of nonstochastic release of exosomes in the lung and couples TLR4 activation with matrikine generation. The increased quantity of these proteolytic exosomes in the airways of subjects with chronic lung disease highlights a new mechanism of injury and inflammation in the pathogenesis of pulmonary disorders.
authors.affiliation: 1 Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine.|2 Program in Protease and Matrix Biology.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Szul
authors.affiliation: 1 Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine.|2 Program in Protease and Matrix Biology.
authors.forename: Preston E
authors.initials: PE
authors.lastname: Bratcher
authors.affiliation: Departments of 3 Neurology and.
authors.forename: Kyle B
authors.initials: KB
authors.lastname: Fraser
authors.affiliation: 4 Pediatrics.|5 Gregory Fleming James Cystic Fibrosis Research Center.
authors.forename: Michele
authors.initials: M
authors.lastname: Kong
authors.affiliation: 2 Program in Protease and Matrix Biology.|6 Department of Pediatrics and Emory+Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University, Atlanta, Georgia; and.
authors.forename: Rabindra
authors.initials: R
authors.lastname: Tirouvanziam
authors.affiliation: 6 Department of Pediatrics and Emory+Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University, Atlanta, Georgia; and.
authors.forename: Sarah
authors.initials: S
authors.lastname: Ingersoll
authors.affiliation: 7 Department of Cell, Developmental and Integrative Biology, and.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Sztul
authors.affiliation: 1 Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine.
authors.forename: Sunil
authors.initials: S
authors.lastname: Rangarajan
authors.affiliation: 1 Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine.|2 Program in Protease and Matrix Biology.|5 Gregory Fleming James Cystic Fibrosis Research Center.|8 University of Alabama at Birmingham Lung Health Center, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: J Edwin
authors.initials: JE
authors.lastname: Blalock
authors.affiliation: 1 Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine.|2 Program in Protease and Matrix Biology.
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.affiliation: 1 Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine.|2 Program in Protease and Matrix Biology.|5 Gregory Fleming James Cystic Fibrosis Research Center.|7 Department of Cell, Developmental and Integrative Biology, and.|8 University of Alabama at Birmingham Lung Health Center, University of Alabama at Birmingham, Birmingham, Alabama.|9 Medicine Service, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama.
authors.forename: Amit
authors.initials: A
authors.lastname: Gaggar
mesh_terms: D000328:Adult; D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000201:enzymology* / Q000382:microbiology; D016022:Case-Control Studies; D002460:Cell Line; D003550:Cystic Fibrosis / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000382:microbiology; D055354:Exosomes / Q000187:drug effects / Q000201:enzymology* / Q000382:microbiology; D005260:Female; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008809:Mice, Inbred C3H; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000378:metabolism*; D000085822:Prolyl Oligopeptidases; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D034622:RNA Interference; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D055815:Young Adult
chemical_list: D008070:Lipopolysaccharides; D024101:Mitochondrial Proteins; C495345:TLR4 protein, human; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C514899:PREP protein, human; D012697:Serine Endopeptidases; C000705287:PREPL protein, human; D000085822:Prolyl Oligopeptidases
keywords: Toll-like receptor 4; cystic fibrosis; exosome; protease; pulmonary