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 5

PAR1 signals via RhoA and Rho kinase to induce αv β6 -mediated TGF-β activation.

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PAR1 signals via RhoA and Rho kinase to induce αv ...
(A) WT mouse embryonic fibroblasts expressing αvβ6 (MEFβ6) were adenovirally infected with GFP, constitutively active (CA) RhoA, or dominant-negative (DN) RhoA. After infection and cell sorting, cells were stimulated (white bars) or were not stimulated (black bars) with 10 μM SFLLRN, and β6-dependent TGF-β activity was calculated from coculture bioassays with TML cells. Unstimulated Par1–/– cells expressing αvβ6 were also infected with an adenovirus encoding a constitutively active RhoA, dominant-negative RhoA, or GFP control and studied in coculture bioassays, as above. (B) IMLE cells and mouse embryonic fibroblasts, both expressing the β6 integrin, were stimulated with 10 μM SFLLRN (dashed lines) in the presence of increasing doses of the Rho kinase inhibitor Y-27632, and αvβ6-mediated TGF-β activity was compared with that of unstimulated IMLE cells (solid lines). (C) MEFβ6 cells were stimulated with 10 μM SFLLRN or 500 pg/ml TGF-β for 4 hours in the presence or absence of the Rho kinase inhibitor Y-27632 and an αvβ6 blocking antibody, and compared with unstimulated cells. Cell lysates were analyzed by Western blotting for phospho-Smad2 or total Smad2. All results are representative of at least 3 independent experiments. *P < 0.005.