title: Targeting protease activated receptor-1 with P1pal-12 limits bleomycin-induced pulmonary fibrosis.
abstract: BACKGROUND
  Idiopathic pulmonary fibrosis is the most devastating fibrotic diffuse parenchymal lung disease which remains refractory to pharmacological therapies. Therefore, novel treatments are urgently required. Protease-activated receptor (PAR)-1 is a G-protein-coupled receptor that mediates critical signalling pathways in pathology and physiology. Bleomycin-induced lung fibrosis has been shown to be diminished in PAR-1-deficient mice. The purpose of this study is to investigate whether pharmacological PAR-1 inhibition is a potential therapeutic option to combat pulmonary fibrosis.
  
  
  METHODS
  Pulmonary fibrosis was induced by intranasal instillation of bleomycin into wild-type mice with or without a specific PAR-1 antagonist (ie, P1pal-12, a pepducin that blocks the PAR-1/G-protein interaction). Fibrosis was assessed by hydroxyproline analysis, immunohistochemistry, quantitative PCR and western blot for fibrotic markers expression.
  
  
  RESULTS
  We first show that P1pal-12 effectively inhibits PAR-1-induced profibrotic responses in fibroblasts. Next, we show that once daily treatment with 0.5, 2.5 or 10 mg/kg P1pal-12 reduced the severity and extent of fibrotic lesions in a dose-dependent manner. These findings correlated with significant decreases in fibronectin, collagen and α smooth muscle actin expression at the mRNA and protein level in treated mice. To further establish the potential clinical applicability of PAR-1 inhibition, we analysed fibrosis in mice treated with P1pal-12 1 or 7 days after bleomycin instillation. Interestingly, when administered 7 days after the induction of fibrosis, P1pal-12 was as effective in limiting the development of pulmonary fibrosis as when administration was started before bleomycin instillation.
  
  
  CONCLUSIONS
  Overall, targeting PAR-1 may be a promising treatment for pulmonary fibrosis.
authors.affiliation: Center for Experimental and Molecular Medicine, Academic Medical Center, , Amsterdam, The Netherlands.
authors.forename: Cong
authors.initials: C
authors.lastname: Lin
authors.forename: Janwillem
authors.initials: J
authors.lastname: Duitman
authors.forename: Joost
authors.initials: J
authors.lastname: Daalhuisen
authors.forename: Marieke
authors.initials: M
authors.lastname: Ten Brink
authors.forename: Jan
authors.initials: J
authors.lastname: von der Thüsen
authors.forename: Tom
authors.initials: T
authors.lastname: van der Poll
authors.forename: Keren
authors.initials: K
authors.lastname: Borensztajn
authors.forename: C Arnold
authors.initials: CA
authors.lastname: Spek
mesh_terms: D000818:Animals; D001761:Bleomycin; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004353:Drug Evaluation, Preclinical / Q000379:methods; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D044463:Receptor, PAR-1 / Q000008:administration & dosage / Q000502:physiology / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors
chemical_list: C587066:P1pal-12 peptide; D010446:Peptide Fragments; D044463:Receptor, PAR-1; D001761:Bleomycin; D003094:Collagen; D010975:Platelet Aggregation Inhibitors
keywords: Idiopathic Pulmonary Fibrosis; Interstitial Fibrosis