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Human cystatin C: A new biomarker of idiopathic pulmonary fibrosis?

Authors

  • Mariana Kasabova,

    1. INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation; Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais, Tours, France
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  • Alix Joulin-Giet,

    1. INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation; Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais, Tours, France
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  • Fabien Lecaille,

    1. INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation; Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais, Tours, France
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  • Ahlame Saidi,

    1. INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation; Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais, Tours, France
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  • Sylvain Marchand-Adam,

    1. INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation; Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais, Tours, France
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  • Gilles Lalmanach

    Corresponding author
    1. INSERM U1100, Pathologies Pulmonaires: Protéolyse et Aérosolthérapie, Equipe 2: Mécanismes Protéolytiques dans l'Inflammation; Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais, Tours, France
    • Correspondence: Professor Dr Gilles Lalmanach, INSERM, UMR 1100 « Pathologies Pulmonaires: Protéolyse et Aérosolthérapie »/CEPR, Faculté de Médecine, Centre d'Etude des Pathologies Respiratoires (CEPR), Université François Rabelais 10 Boulevard Tonnellé, F – 37032 Tours cedex, France

      E-mail: gilles.lalmanach@univ-tours.fr

      Fax: +33-247366046

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Abstract

Purpose

Human idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disorder with a poor prognosis. The identification of a new and specific biomarker in bronchoalveolar lavage fluids (BALFs) may assist in the diagnosis of the disease.

Experimental design

Characterization of cysteine Cats and their endogenous inhibitor, cystatin C, was conducted by immunochemical analysis and measurement of endopeptidase activity of control (n = 11) and IPF (n = 25) BALFs (normalized conditions, 20 μg protein/assay).

Results

Cathepsin (Cat) B was detected as proform and mature enzyme for both control and IPF samples, while Cats K, L, and S were found as zymogens with a strengthened staining in IPF BALFs. The overall endopeptidase activity related mainly to Cat B and did not vary significantly between control and IPF samples. Conversely a significant increase of immunoreactive cystatin C was measured in BALFs for each of three IPF grades.

Conclusions and clinical relevance

An excessive deposition of extracellular matrix proteins is the hallmark of fibrotic disorders. Cats are potent collagenases and might be essential for lung homeostasis. Taken together, increase of cystatin C in IPF BALFs may reflect abnormal regulation of proteolytic activity of Cats in lung, which in turn can promote the development of fibrosis.

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