title: An antagonist of the platelet-activating factor receptor inhibits adherence of both nontypeable Haemophilus influenzae and Streptococcus pneumoniae to cultured human bronchial epithelial cells exposed to cigarette smoke.
abstract: BACKGROUND
  COPD is emerging as the third largest cause of human mortality worldwide after heart disease and stroke. Tobacco smoking, the primary risk factor for the development of COPD, induces increased expression of platelet-activating factor receptor (PAFr) in the lung epithelium. Nontypeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae adhere to PAFr on the luminal surface of human respiratory tract epithelial cells.
  
  
  OBJECTIVE
  To investigate PAFr as a potential drug target for the prevention of infections caused by the main bacterial drivers of acute exacerbations in COPD patients, NTHi and S. pneumoniae.
  
  
  METHODS
  Human bronchial epithelial BEAS-2B cells were exposed to cigarette smoke extract (CSE). PAFr expression levels were determined using immunocytochemistry and quantitative polymerase chain reaction. The epithelial cells were challenged with either NTHi or S. pneumoniae labeled with fluorescein isothiocyanate, and bacterial adhesion was measured using immunofluorescence. The effect of a well-evaluated antagonist of PAFr, WEB-2086, on binding of the bacterial pathogens to BEAS-2B cells was then assessed. In silico studies of the tertiary structure of PAFr and the binding pocket for PAF and its antagonist WEB-2086 were undertaken.
  
  
  RESULTS
  PAFr expression by bronchial epithelial cells was upregulated by CSE, and significantly associated with increased bacterial adhesion. WEB-2086 reduced the epithelial adhesion by both NTHi and S. pneumoniae to levels observed for non-CSE-exposed cells. Furthermore, it was nontoxic toward the bronchial epithelial cells. In silico analyses identified a binding pocket for PAF/WEB-2086 in the predicted PAFr structure.
  
  
  CONCLUSIONS
  WEB-2086 represents an innovative class of candidate drugs for inhibiting PAFr-dependent lung infections caused by the main bacterial drivers of smoking-related COPD.
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Shakti D
authors.initials: SD
authors.lastname: Shukla
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Rory L
authors.initials: RL
authors.lastname: Fairbairn
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Gell
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Roger D
authors.initials: RD
authors.lastname: Latham
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia; School of Health Sciences, Faculty of Health, University of Tasmania, Launceston, TAS, Australia.
authors.forename: Sukhwinder S
authors.initials: SS
authors.lastname: Sohal
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Eugene H
authors.initials: EH
authors.lastname: Walters
authors.affiliation: Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Ronan F
authors.initials: RF
authors.lastname: O'Toole
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001381:Azepines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects*; D001665:Binding Sites; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D006192:Haemophilus Infections / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000472:pathogenicity; D054884:Host-Pathogen Interactions; D006801:Humans; D062105:Molecular Docking Simulation; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D011008:Pneumococcal Infections / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control*; D011485:Protein Binding; D011487:Protein Conformation; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D012906:Smoke / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects*; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000472:pathogenicity; D014230:Triazoles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001381:Azepines; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D012906:Smoke; D014230:Triazoles; C039351:platelet activating factor receptor; C052518:WEB 2086
keywords: NTHi; PAFr antagonist; WEB-2086; airway epithelium; platelet-activating factor receptor; pneumococci