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Acid Attack and Cathepsin K in Bone Resorption Around Total Hip Replacement Prosthesis
Author(s) -
Konttinen Yrjö T.,
Takagi Michiaki,
Mandelin Jami,
Lassus Jan,
Salo Jari,
Ainola Mari,
Li TianFang,
Virtanen Ismo,
Liljeström Mikko,
Sakai Hideaki,
Kobayashi Yasuhiro,
Sorsa Timo,
Lappalainen Reijo,
Demulder Anne,
Santavirta Seppo
Publication year - 2001
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.2001.16.10.1780
Subject(s) - cathepsin k , chemistry , osteoclast , cathepsin , resorption , bone resorption , extracellular matrix , acid phosphatase , osteoid , bone remodeling , microbiology and biotechnology , biochemistry , pathology , anatomy , biology , endocrinology , enzyme , medicine , in vitro
Normal bone remodeling and pathological bone destruction have been considered to be osteoclast‐driven. Osteoclasts are able to attach to bare bone surface and produce an acidic subcellular space. This leads to acid dissolution of hydroxyapatite, allowing cathepsin K to degrade the organic type I collagen‐rich osteoid matrix under the acidic condition prevailing in Howship lacunae. Using a sting pH electrode, the interface membrane around a loosened total hip replacement prosthesis was found to be acidic. Confocal laser scanning disclosed irregular demineralization of the bone surface in contact with the acidic interface. Cathepsin K, an acidic collagenolytic enzyme, was found in interface tissue macrophages/giant cells and pseudosynovial fluid. Tissue extracts contained high levels of cathepsin K messenger RNA (mRNA) and protein. These observations suggest the presence of an acid‐ and cathepsin K‐driven pathological mechanism of bone resorption, mediated not by osteoclasts in subosteoclastic space, but rather by the uncontrolled activity of macrophages in extracellular space.