Regulation of TGF-β1-driven differentiation of human lung fibroblasts: emerging roles of cathepsin B and cystatin C.
Lung matrix homeostasis partly depends on the fine regulation of proteolytic activities. We examined the expression of human cysteine cathepsins (Cats) and their relative contribution to TGF-β1-induced fibroblast differentiation into myofibroblasts. Assays were conducted using both primary fibroblasts obtained from patients with idiopathic pulmonary fibrosis and human lung CCD-19Lu fibroblasts. Pharmacological inhibition and genetic silencing of Cat B diminished α-smooth muscle actin expression, delayed fibroblast differentiation, and led to an accumulation of intracellular 50-kDa TGF-β1. Moreover, the addition of Cat B generated a 25-kDa mature form of TGF-β1 in Cat B siRNA-pretreated lysates. Inhibition of Cat B decreased Smad 2/3 phosphorylation but had no effect on p38 MAPK and JNK phosphorylation, indicating that Cat B mostly disturbs TGF-β1-driven canonical Smad signaling pathway. Although mRNA expression of cystatin C was stable, its secretion, which was inhibited by brefeldin A, increased during TGF-β1-induced differentiation of idiopathic pulmonary fibrosis and CCD-19Lu fibroblasts. In addition, cystatin C participated in the control of extracellular Cats, because its gene silencing restored their proteolytic activities. These data support the notion that Cat B participates in lung myofibrogenesis as suggested for stellate cells during liver fibrosis. Moreover, we propose that TGF-β1 promotes fibrosis by driving the effective cystatin C-dependent inhibition of extracellular matrix-degrading Cats.
From the INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation, Centre d'Etude des Pathologies Respiratoires, Université François Rabelais, Faculté de Médecine, F-37032 Tours, France and.
Mariana
M
Kasabova
From the INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation, Centre d'Etude des Pathologies Respiratoires, Université François Rabelais, Faculté de Médecine, F-37032 Tours, France and.
Alix
A
Joulin-Giet
From the INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation, Centre d'Etude des Pathologies Respiratoires, Université François Rabelais, Faculté de Médecine, F-37032 Tours, France and.
Fabien
F
Lecaille
the Queen's University Belfast, School of Pharmacy, McClay Research Centre, Belfast, BT9 7BL, United Kingdom.
Brendan F
BF
Gilmore
From the INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation, Centre d'Etude des Pathologies Respiratoires, Université François Rabelais, Faculté de Médecine, F-37032 Tours, France and.
Sylvain
S
Marchand-Adam
From the INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation, Centre d'Etude des Pathologies Respiratoires, Université François Rabelais, Faculté de Médecine, F-37032 Tours, France and.
Ahlame
A
Saidi
From the INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation, Centre d'Etude des Pathologies Respiratoires, Université François Rabelais, Faculté de Médecine, F-37032 Tours, France and gilles.lalmanach@univ-tours.fr.
Gilles
G
Lalmanach
D015153:Blotting, Western; D002401:Cathepsin B / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D055316:Cystatin C / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology; D020868:Gene Silencing; D006801:Humans; D008168:Lung / Q000166:cytology*; D010766:Phosphorylation; D034622:RNA Interference; D034741:RNA, Small Interfering; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000502:physiology*
D055316:Cystatin C; D034741:RNA, Small Interfering; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; D002401:Cathepsin B
Collagen; Cysteine Protease; Protease; Protease Inhibitor; Pulmonary Fibrosis; Smad Pathway