title: Lactoperoxidase and human airway host defense.
abstract: The lactoperoxidase (LPO) antibiotic system is a well-characterized component of mammary and salivary gland secretions. Because LPO has been shown to function in ovine airways, human airway tissue and secretions were examined for the presence of LPO and its substrate, the anion thiocyanate (SCN-). In addition, human airway secretions were tested for LPO-mediated antibacterial activity, and LPO's activity was assessed against some human airway pathogens. The data showed that normal human airway secretions contained LPO enzyme activity (0.65 +/- 0.09 microg/mg secreted protein; n = 17), and Western blots of secretions demonstrated bands of the expected sizes for LPO. LPO mRNA was detected in trachea by sequencing PCR-amplified cDNA. SCN-, LPO's substrate, was present in undiluted airway secretions at concentrations sufficient for LPO catalysis (0.46 +/- 0.19 mM; n = 8), and diluted secretions contained antibacterial activity with LPO-like properties. Immunocytochemistry localized LPO to submucosal glands in human bronchi. Finally, as expected based on the known antibacterial spectrum of the LPO system, airway secretions showed LPO-dependent activity against Pseudomonas aeruginosa. In addition, the airway LPO system was shown to be effective against Burkholderia cepacia and Haemophilus influenzae. Thus, a functional LPO system exists in human airways and may contribute to airway host defense against infection.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101, USA.
authors.forename: Corinne
authors.initials: C
authors.lastname: Wijkstrom-Frei
authors.forename: Souheil
authors.initials: S
authors.lastname: El-Chemaly
authors.forename: Radia
authors.initials: R
authors.lastname: Ali-Rachedi
authors.forename: Cynthia
authors.initials: C
authors.lastname: Gerson
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Cobas
authors.forename: Rosanna
authors.initials: R
authors.lastname: Forteza
authors.forename: Matthias
authors.initials: M
authors.lastname: Salathe
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Conner
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016956:Burkholderia cepacia / Q000378:metabolism; D002384:Catalysis; D002417:Cattle; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006193:Haemophilus influenzae / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D007784:Lactoperoxidase / Q000378:metabolism*; D008956:Models, Chemical; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013861:Thiocyanates / Q000378:metabolism; D013997:Time Factors; D014132:Trachea / Q000201:enzymology* / Q000378:metabolism / Q000382:microbiology*
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D013861:Thiocyanates; D007784:Lactoperoxidase; C031760:thiocyanate