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Cathepsin K – a marker of macrophage differentiation?
Author(s) -
Bühling F.,
Reisenauer A.,
Gerber A.,
Krüger S.,
Weber E.,
Brömme D.,
Roessner A.,
Ansorge S.,
Welte T.,
Röcken Ch.
Publication year - 2001
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.959
Subject(s) - giant cell , cathepsin , cathepsin k , pathology , biology , macrophage , cathepsin b , multinucleate , microbiology and biotechnology , osteoclast , medicine , biochemistry , in vitro , enzyme
Cathepsin K is a cysteine protease with high matrix‐degrading activity. Initially, cathepsin K was described as being expressed exclusively by osteoclasts. It was suggested that cathepsin K expression is a specific feature of cells involved in bone remodelling. The aim of this study was to investigate the hypothesis that cathepsin K is expressed not only in bone‐resorbing macrophages, but also more generally in specifically differentiated macrophages, such as epithelioid cells and multinucleated giant cells in soft tissues. Specimens obtained from different organs and anatomical locations of patients suffering from sarcoidosis, tuberculosis, granulomas caused by foreign materials, and sarcoid‐like lesions were investigated for the expression of cathepsins B, K, and L. Immunohistochemistry and in situ hybridization showed cathepsin K in epithelioid cells and multinucleated giant cells irrespective of the pathological condition and anatomical location, but not in normal resident macrophages. By immunoelectron microscopy, cathepsin K was discovered in cytoplasmic granules of multinucleated giant cells. In contrast, cathepsin B and cathepsin L were expressed ubiquitously in CD68‐positive tissue macrophages, epithelioid cells, and multinucleated giant cells. The results demonstrate that cathepsin K, but not cathepsin B or cathepsin L, differentiates specific phenotypes of macrophages independently of the anatomical site. Its enzymatic characteristics, particularly its high matrix‐degrading activity, suggest that cathepsin K‐positive epithelioid cells and multinucleated giant cells are characterized by an enhanced specific proteolytic capability. Copyright © 2001 John Wiley & Sons, Ltd.