Ligation of protease-activated receptor 1 enhances αv β6 integrin–dependent TGF-β activation and promotes acute lung injury
R. Gisli Jenkins, … , Michael A. Matthay, Dean Sheppard
R. Gisli Jenkins, … , Michael A. Matthay, Dean Sheppard
Published June 1, 2006
Citation Information: J Clin Invest. 2006;116(6):1606-1614. https://doi.org/10.1172/JCI27183.
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Research Article Pulmonology

Ligation of protease-activated receptor 1 enhances αv β6 integrin–dependent TGF-β activation and promotes acute lung injury

Abstract

Activation of latent TGF-β by the αvβ6 integrin is a critical step in the development of acute lung injury. However, the mechanism by which αvβ6-mediated TGF-β activation is regulated has not been identified. We show that thrombin, and other agonists of protease-activated receptor 1 (PAR1), activate TGF-β in an αvβ6 integrin–specific manner. This effect is PAR1 specific and is mediated by RhoA and Rho kinase. Intratracheal instillation of the PAR1-specific peptide TFLLRN increases lung edema during high-tidal-volume ventilation, and this effect is completely inhibited by a blocking antibody against the αvβ6 integrin. Instillation of TFLLRN during high-tidal-volume ventilation is associated with increased pulmonary TGF-β activation; however, this is not observed in Itgb6–/– mice. Furthermore, Itgb6–/– mice are also protected from ventilator-induced lung edema. We also demonstrate that pulmonary edema and TGF-β activity are similarly reduced in Par1–/– mice following bleomycin-induced lung injury. These results suggest that PAR1-mediated enhancement of αvβ6-dependent TGF-β activation could be one mechanism by which activation of the coagulation cascade contributes to the development of acute lung injury, and they identify PAR1 and the αvβ6 integrin as potential therapeutic targets in this condition.

Authors

R. Gisli Jenkins, Xiao Su, George Su, Christopher J. Scotton, Eric Camerer, Geoffrey J. Laurent, George E. Davis, Rachel C. Chambers, Michael A. Matthay, Dean Sheppard

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Figure 4

PAR1 peptide–induced αv β6 -dependent TGF-β activity is PAR1 receptor specific.

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PAR1 peptide–induced αv β6 ...
(A) αvβ6-dependent TGF-β activity following stimulation of mouse embryonic fibroblast cells, stably transfected with human WT β6, with increasing doses of the PAR1-activating peptides TFLLRN and SFLLRN or the scrambled peptide control (FSLLRN), which has no known PAR1-activating effect. αvβ6-dependent TGF-β activity was calculated from coculture bioassays with TML cells, by comparison of the difference in luciferase activity in the absence and presence of αvβ6 blocking antibody with values obtained from a standard curve performed in coculture experiments with increasing concentrations of recombinant TGF-β. (B) After infection with a retroviral vector expressing WT human β6, αvβ6 expression in lung fibroblasts from Par1–/– mice that were either null (Par1–/–) or reconstituted with WT PAR1 (Par1+) was assessed by flow cytometry. (C) αvβ6-expressing Par1–/– and Par1+ fibroblasts were stimulated with increasing doses of SFLLRN, and αvβ6-dependent TGF-β activity was measured by coculture bioassay.