• Olivier Bardou, Awen Menou, Charlène François, Jan Willem Duitman, Jan H von der Thüsen, Raphaël Borie, Katiuchia Uzzun Sales, Kathrin Mutze, Yves Castier, Edouard Sage, Ligong Liu, Thomas H Bugge, David P Fairlie, Mélanie Königshoff, Bruno Crestani, and Keren S Borensztajn.
• 1 Inserm UMR1152, Medical School Xavier Bichat, Paris, France.
• Am. J. Respir. Crit. Care Med. 2016 Apr 15; 193 (8): 847-60.

RationaleIdiopathic pulmonary fibrosis (IPF) is a devastating disease that remains refractory to current therapies.ObjectivesTo characterize the expression and activity of the membrane-anchored serine protease matriptase in IPF in humans and unravel its potential role in human and experimental pulmonary fibrogenesis.MethodsMatriptase expression was assessed in tissue specimens from patients with IPF versus control subjects using quantitative reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blotting, while matriptase activity was monitored by fluorogenic substrate cleavage. Matriptase-induced fibroproliferative responses and the receptor involved were characterized in human primary pulmonary fibroblasts by Western blot, viability, and migration assays. In the murine model of bleomycin-induced pulmonary fibrosis, the consequences of matriptase depletion, either by using the pharmacological inhibitor camostat mesilate (CM), or by genetic down-regulation using matriptase hypomorphic mice, were characterized by quantification of secreted collagen and immunostainings.Measurements And Main ResultsMatriptase expression and activity were up-regulated in IPF and bleomycin-induced pulmonary fibrosis. In cultured human pulmonary fibroblasts, matriptase expression was significantly induced by transforming growth factor-β. Furthermore, matriptase elicited signaling via protease-activated receptor-2 (PAR-2), and promoted fibroblast activation, proliferation, and migration. In the experimental bleomycin model, matriptase depletion, by the pharmacological inhibitor CM or by genetic down-regulation, diminished lung injury, collagen production, and transforming growth factor-β expression and signaling.ConclusionsThese results implicate increased matriptase expression and activity in the pathogenesis of pulmonary fibrosis in human IPF and in an experimental mouse model. Overall, targeting matriptase, or treatment by CM, which is already in clinical use for other diseases, may represent potential therapies for IPF.

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