title: The role of protease-activated receptors PAR-1 and PAR-2 in the repair of 16HBE 14o(-) epithelial cell monolayers in vitro.
abstract: BACKGROUND
  We recently reported that repair following mechanical wounding of epithelial cell layers in vitro is dependent on fibrin formation and the activity of locally expressed coagulation cascade proteins. Serine proteases of the coagulation cascade are an important group of protease-activated receptor (PAR) activators and PAR-1 to 4 are expressed by the normal bronchial epithelium.
  
  
  OBJECTIVE
  We tested the hypothesis that activation of PAR-1 and PAR-2 by coagulation cascade proteases stimulates epithelial repair via effects on fibrin formation.
  
  
  METHODS
  Using mechanically wounded 16HBE 14o(-) epithelial cell layers in culture, we investigated the effect of PAR-1 and PAR-2 agonist peptides, control partially scrambled peptides and PAR-neutralizing antibodies on the rate of repair and fibrin formation. Coagulation factors in culture supernatants were measured by immunoblot. RT-PCR was used to investigate PAR-1, PAR-2 and PGE2 receptor (EP-1 to EP-4) expression in this model and qRT-PCR to quantify responses to wounding. Additionally, we investigated the effect of exogenously added factor Xa (FXa) and neutrophil elastase and the influence of PGE2 and indomethacin on the repair response.
  
  
  RESULTS
  PAR-1 and PAR-2 peptide agonists stimulated the rate of repair and enhanced the formation of a fibrin provisional matrix to support the repair process. Conversely, PAR-neutralizing antibodies inhibited repair. Under serum-free culture conditions, 16HBE 14o(-) cells expressed EP-2 and EP-3, but not EP-1 or EP-4, receptors. Wounding induced an increased expression of EP-3 but did not alter EP-2, PAR-1 or PAR-2 expression. In the absence of PAR agonists, there was no evidence for a role for PGE2 in fibrin formation or the repair process. Indomethacin attenuated fibrin formation in wounded cultures only in the presence of the PAR-2 peptide. FXa stimulated epithelial repair while neutrophil elastase reduced the levels of coagulation factors and inhibited repair.
  
  
  CONCLUSIONS
  Locally expressed serine proteases of the coagulation cascade activate PAR-1 and PAR-2 to enhance fibrin formation and bronchial epithelial repair.
authors.affiliation: Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, Hampshire, UK.
authors.forename: D
authors.initials: D
authors.lastname: Ewen
authors.forename: S L
authors.initials: SL
authors.lastname: Clarke
authors.forename: J R
authors.initials: JR
authors.lastname: Smith
authors.forename: C
authors.initials: C
authors.lastname: Berger
authors.forename: G
authors.initials: G
authors.lastname: Salmon
authors.forename: M
authors.initials: M
authors.lastname: Trevethick
authors.forename: J K
authors.initials: JK
authors.lastname: Shute
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015951:Factor Xa / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D019272:Leukocyte Elastase / Q000378:metabolism / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D044463:Receptor, PAR-1 / Q000819:agonists / Q000378:metabolism*; D044464:Receptor, PAR-2 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010975:Platelet Aggregation Inhibitors
chemical_list: D000906:Antibodies; D009842:Oligopeptides; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D019272:Leukocyte Elastase; D015951:Factor Xa; D015232:Dinoprostone; D007213:Indomethacin; D010975:Platelet Aggregation Inhibitors