Neutrophilic Cathepsin C Is Maturated by a Multistep Proteolytic Process and Secreted by Activated Cells during Inflammatory Lung Diseases

Yveline Hamon,Monika Legowska,Virginie Hervé,Sandrine Dallet-Choisy,Sylvain Marchand-Adam,Lise Vanderlynden,Michèle Demonte,Rich Williams,Christopher J Scott,Mustapha Si-Tahar,Nathalie Heuzé-Vourc'H,Gilles Lalmanach,Dieter E Jenne,Adam Lesner,Francis Gauthier,Brice Korkmaz

doi:10.1074/jbc.m115.707109

Abstract

The cysteine protease cathepsin C (CatC) activates granule-associated proinflammatory serine proteases in hematopoietic precursor cells. Its early inhibition in the bone marrow is regarded as a new therapeutic strategy for treating proteolysis-driven chronic inflammatory diseases, but its complete inhibition is elusive in vivo Controlling the activity of CatC may be achieved by directly inhibiting its activity with a specific inhibitor or/and by preventing its maturation. We have investigated immunochemically and kinetically the occurrence of CatC and its proform in human hematopoietic precursor cells and in differentiated mature immune cells in lung secretions. The maturation of proCatC obeys a multistep mechanism that can be entirely managed by CatS in neutrophilic precursor cells. CatS inhibition by a cell-permeable inhibitor abrogated the release of the heavy and light chains from proCatC and blocked ∼80% of CatC activity. Under these conditions the activity of neutrophil serine proteases, however, was not abolished in precursor cell cultures. In patients with neutrophilic lung inflammation, mature CatC is found in large amounts in sputa. It is secreted by activated neutrophils as confirmed through lipopolysaccharide administration in a nonhuman primate model. CatS inhibitors currently in clinical trials are expected to decrease the activity of neutrophilic CatC without affecting those of elastase-like serine proteases.

Highlights

Cathepsin C (CatC)3 (EC 3.4.14.1), known as dipeptidyl peptidase I, is a member of cysteine cathepsins, which are lysosomal proteases belonging to the C1 family of papain-like cysteine peptidases [1,2,3]
Active CatC was not detected in the cell-free supernatant of undifferentiated PLB-985 activated by A23187, but it was found in supernatants after these cells had been differentiated into neutrophil-like cells and in mature neutrophils (Fig. 2, C and D)
The biosynthetically generated, active proteases are stored in the granules of cytotoxic T lymphocytes and natural killer cells, mast cells, and neutrophils (15, 34 –36)

Summary

The abbreviations used are

Cathepsin; AM, alveolar macrophages; BALF, broncho-alveolar lavage fluids; CF, cystic fibrosis; NSP, neutrophil serine protease; PR3, proteinase 3; AMC, aminomethylcoumarin; DMF, dimethylformamide; WB, Western blotting; Boc, t-butoxycarbonyl; Bt, biotin; CHN2, diazomethane; Thi, ␤-(2-thienyl)-alanine; Abz, 2-aminobenzoic acid, EDDnp, N-(2,4-dinitrophenyl)ethylendiamine. The best characterized physiological function of CatC is the processing of granule-associated serine proteases including human neutrophil elastase, proteinase 3 (PR3), cathepsin G (CatG), mast cell chymase, and lymphocyte granzymes A and B [1, 15] in immune defense cells. These serine proteases from immune cells can participate in the progression of a variety of inflammatory diseases including those that affect the respiratory system. We looked for the presence of CatC in the lung secretions of nonhuman primates with lung inflammation and in patients with neutrophilic inflammation

Experimental Procedures

Results

Discussion