Localization of cathepsin K and tartrate-resistant acid phosphatase in synovium and cranial cruciate ligament in dogs with cruciate disease.

OBJECTIVE: To localize cathepsin K and tartrate-resistant acid phosphatase (TRAP) in synovium and cranial cruciate ligament (CCL) of dogs with cruciate disease. ANIMALS: Dogs (n=15) with cruciate disease and ruptured CCL, and 12 dogs with intact CCL.
METHODS: Synovium and CCL were examined histologically and cells containing cathepsin K or TRAP were identified immunohistochemically and histochemically, respectively.
RESULTS: Increased cellular localization of cathepsin K and TRAP was detected in synovium and ruptured CCL in dogs with cruciate disease, when compared with tissues from dogs with intact CCL. Inflammation of synovium with TRAP+ macrophage-like cells was seen in 73% of dogs with CCL disease, but was not seen in dogs with intact CCL. The presence of cathepsin K and TRAP protein in synovium and CCL tissues was significantly correlated in dogs with CCL rupture.
CONCLUSION: Inflammation of the epiligament of ruptured CCL with cathepsin K+ and TRAP+ macrophage-like cells forms part of a similar, more generalized chronic inflammatory change within the periarticular tissues of the stifle of a large proportion of dogs with CCL rupture. CLINICAL RELEVANCE: Production of matrix-degrading enzymes by the synovium may induce progressive pathologic rupture of the CCL. Therefore, these collagenolytic pathways may offer a novel target for medical therapy of joint inflammation in canine patients with cruciate disease.