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Biochemical identification and immunolocalizaton of aggrecan, ADAMTS5 and inter‐alpha‐trypsin–inhibitor in equine degenerative suspensory ligament desmitis
Author(s) -
Plaas Anna,
Sandy John D.,
Liu Haowen,
Diaz Michael A.,
Schenkman Daniel,
Magnus Robert P.,
BolamBretl Courtney,
Kopesky Paul W.,
Wang Vincent M.,
Galante Jorge O.
Publication year - 2011
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.21332
Subject(s) - aggrecan , versican , chemistry , ligament , decorin , aggrecanase , anatomy , proteoglycan , extracellular matrix , pathology , osteoarthritis , medicine , biochemistry , articular cartilage , alternative medicine
We describe analysis of suspensory ligaments from horses with advanced degenerative suspensory ligament desmitis (DSLD) to identify the major proteoglycans (PGs), ADAMTS‐aggrecanases and inter‐alpha‐trypsin inhibitor (IαI) components associated with ligament degeneration. Specific anatomical regions of suspensory ligaments from two normal horses and four diagnosed with DSLD were analyzed by Western blot and immunohistochemistry for the following: aggrecan, aggrecan fragments, decorin, ADAMTS4, ADAMTS5, and IαI components. When compared to normal, DSLD ligaments showed about a 15‐fold increase ( P < 0.0014) in aggrecan levels and markedly enhanced staining with Safranin O. The aggrecan was composed of two distinct high molecular weight core protein species. The largest species was found only in DSLD samples and it co‐migrated with aggrecan synthesized by equine mesenchymal stem cells (MSC). Many of the DSLD samples also contained abnormally high concentrations of ADAMTS4, ADAMTS5, and IαI. Notably, the ADAMTS5 in DSLD samples, but not normals, was present largely as a high molecular weight complex. We conclude that ligament degeneration in DSLD is associated with matrix changes characteristic of an inflammatory nonhealing wound, specifically containing chondrogenic progenitor cells. Since aggrecan accumulation is a major feature of incomplete healing in tendon and skin of the ADAMTS5 knockout mouse, we propose that ligament failure in DSLD results from a process involving tissue inflammation and the complexation of ADAMTS5. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:900–906