title: The role and regulation of Moraxella catarrhalis-induced human beta-defensin 3 expression in human pulmonary epithelial cells.
abstract: BACKGROUND
  Bacterial colonisation with Moraxella catarrhalis may partly sustain chronic inflammation in the lower airways of patients with chronic obstructive pulmonary disease (COPD). In addition, this bacterium causes infectious exacerbations of COPD, which often necessitate treatment with antibiotics. Antimicrobial peptides are the body's own antibiotic substances with bactericidal and bacteriostatic, as well as immunomodulatory function. In particular, human beta-defensin 3 (hBD-3) exerts an antimicrobial effect against an extraordinarily broad spectrum of pathogens. We therefore investigated the role of hBD-3 in infections of pulmonary epithelial cells with M. catarrhalis.
  
  
  METHODS
  The antimicrobial activity of hBD-3 vs. M. catarrhalis was evaluated in an antimicrobial susceptibility assay. We analyzed hBD-3 secretion of M. catarrhalis-infected pulmonary epithelial cells using ELISA. The role of M. catarrhalis-specific virulence factors, toll-like receptors (TLR) 2 and 4, MAPK pathways, and transcription factors AP-1 and NF-κB in the induction and regulation of hBD-3 expression were explored with specific inhibitors, small interference RNA, Western Blot, and chromatin immunoprecipitation (ChIP) assays.
  
  
  RESULTS
  HBD-3 exhibited a strong bactericidal effect against M. catarrhalis. M. catarrhalis induced hBD-3 expression in pulmonary epithelial cells, which was dependent on M. catarrhalis membranous lipoolygosaccharide (LOS), while the surface proteins UspA1 and UspA2 were not involved. Gene silencing of TLR2, but not TLR4, led to a reduced hBD-3 secretion after stimulation with M. catarrhalis or M. catarrhalis LOS. Inhibition of MAPKs ERK1/2 and JNK, but not p38, reduced hBD-3 secretion. HBD-3 expression was mediated through the recruitment of AP-1 to the hBD-3 gene promoter and was independent of NF-κB.
  
  
  CONCLUSIONS
  The immune response of pulmonary epithelial cells towards M. catarrhalis involves secretion of hBD-3, which has a bactericidal effect against this pathogen. Binding of M. catarrhalis virulence factor LOS to TLR2 causes an ERK1/2- and JNK-dependent induction of AP-1-related transcription of the hBD-3 gene, resulting in the production and secretion of hBD-3.
authors.affiliation: Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany; Department of Internal Medicine/Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Haarmann
authors.affiliation: Department of Internal Medicine/Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany; Neurological Rehabilitation Center for Children and Adolescents, Helios Klinikum Hohenstücken, Brandenburg, Germany.
authors.forename: Tamara
authors.initials: T
authors.lastname: Steiner
authors.affiliation: ZIK Septomics, University Hospital Jena, Jena, Germany.
authors.forename: Frauke
authors.initials: F
authors.lastname: Schreiber
authors.affiliation: ZIK Septomics, University Hospital Jena, Jena, Germany.
authors.forename: Annina
authors.initials: A
authors.lastname: Heinrich
authors.affiliation: Department of Infection Control and Hospital Hygiene, University Hospital Cologne, Cologne, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Zweigner
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Red Cross Hospital, Stuttgart, Germany.
authors.forename: Philippe Dje
authors.initials: PD
authors.lastname: N'Guessan
authors.affiliation: ZIK Septomics, University Hospital Jena, Jena, Germany. Electronic address: hortense.slevogt@med.uni-jena.de.
authors.forename: Hortense
authors.initials: H
authors.lastname: Slevogt
mesh_terms: D002460:Cell Line; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D005786:Gene Expression Regulation; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology; D008168:Lung / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D020935:MAP Kinase Signaling System; D001936:Moraxella catarrhalis / Q000276:immunology / Q000472:pathogenicity*; D045828:Moraxellaceae Infections / Q000150:complications; D016328:NF-kappa B / Q000378:metabolism; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology / Q000378:metabolism / Q000382:microbiology; D020545:Respiratory Mucosa / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D023083:beta-Defensins / Q000235:genetics / Q000378:metabolism*
chemical_list: C422950:DEFB103A protein, human; D008070:Lipopolysaccharides; D016328:NF-kappa B; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D018808:Transcription Factor AP-1; D023083:beta-Defensins; C023023:lipid-linked oligosaccharides
keywords: Antimicrobial peptides; Chronic obstructive pulmonary disease; Human beta-defensin 3; Moraxella catarrhalis; Pulmonary epithelial cells; Toll-like receptor 2