Protease-activated receptor (PAR)-2 is required for PAR-1 signalling in pulmonary fibrosis.

Abstract

Idiopathic pulmonary fibrosis is the most devastating diffuse fibrosing lung disease of unknown aetiology. Compelling evidence suggests that both protease-activated receptor (PAR)-1 and PAR-2 participate in the development of pulmonary fibrosis. Previous studies have shown that bleomycin-induced lung fibrosis is diminished in both PAR-1 and PAR-2 deficient mice. We thus have been suggested that combined inactivation of PAR-1 and PAR-2 would be more effective in blocking pulmonary fibrosis. Human and murine fibroblasts were stimulated with PAR-1 and PAR-2 agonists in the absence or presence of specific PAR-1 or PAR-2 antagonists after which fibrotic markers like collagen and smooth muscle actin were analysed by Western blot. Pulmonary fibrosis was induced by intranasal instillation of bleomycin into wild-type and PAR-2 deficient mice with or without a specific PAR-1 antagonist (P1pal-12). Fibrosis was assessed by hydroxyproline quantification and (immuno)histochemical analysis. We show that specific PAR-1 and/or PAR-2 activating proteases induce fibroblast migration, differentiation and extracellular matrix production. Interestingly, however, combined activation of PAR-1 and PAR-2 did not show any additive effects on these pro-fibrotic responses. Strikingly, PAR-2 deficiency as well as pharmacological PAR-1 inhibition reduced bleomycin-induced pulmonary fibrosis to a similar extent. PAR-1 inhibition in PAR-2 deficient mice did not further diminish bleomycin-induced pulmonary fibrosis. Finally, we show that the PAR-1-dependent pro-fibrotic responses are inhibited by the PAR-2 specific antagonist. Targeting PAR-1 and PAR-2 simultaneously is not superior to targeting either receptor alone in bleomycin-induced pulmonary fibrosis. We postulate that the pro-fibrotic effects of PAR-1 require the presence of PAR-2.

• Authors: Cong Lin, Jan von der Thüsen, Joost Daalhuisen, Marieke ten Brink, Bruno Crestani, Tom van der Poll, Keren Borensztajn, C Arnold Spek
• Journal: Journal of cellular and molecular medicine (J Cell Mol Med) Vol. 19 Issue 6 Pg. 1346-56 (Jun 2015) ISSN: 1582-4934 [Electronic] England
• PMID: 25689283 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Chemical References

• Actins
• P1pal-12 peptide
• Peptide Fragments
• Receptor, PAR-1
• Receptor, PAR-2
• Bleomycin
• Collagen
• Extracellular Signal-Regulated MAP Kinases
• Trypsin
• Thrombin
• Hydroxyproline

Topics

• Actins (metabolism)
• Animals
• Bleomycin
• Blotting, Western
• Collagen (metabolism)
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Fibroblasts (drug effects, metabolism)
• Humans
• Hydroxyproline (metabolism)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• NIH 3T3 Cells
• Peptide Fragments (pharmacology)
• Phosphorylation (drug effects)
• Pulmonary Fibrosis (chemically induced, genetics, metabolism)
• Receptor, PAR-1 (antagonists & inhibitors, genetics, metabolism)
• Receptor, PAR-2 (antagonists & inhibitors, genetics, metabolism)
• Signal Transduction
• Thrombin (pharmacology)
• Trypsin (pharmacology)