SummaryTo better understand the mechanisms responsible for the pathological processes of osteoarthritis (OA) and to potentially identify a profile of changes that could be predictive of early OA, matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in the synovial fluid and serum of normal and osteoarthritic dogs were examined. The concentration of MMP-1 in the synovial fluid of osteoarthritic dogs (0.62 ± 0.16), as measured by densitometry, was significantly higher than that found in control dogs (0.42 ± 0.19) (P = 0.03). The concentration of MMP-1 in the serum of osteoarthritic dogs (0.74 ± 0.16) was significantly less than that found in control dogs (0.87 ± 0.08) (P = 0.05). The concentration of TIMP-2 in the synovial fluid of osteoarthritic dogs (46.2 ± 21.9 ng/ml) was significantly less than that of control dogs (122.0 ± 66.5 ng/ml) (P = 0.009). The concentration of TIMP-2 in the serum of osteoarthritic dogs (116.2 ± 43.1 ng/ml) was not significantly different than that of control dogs (95.1 ± 94.4 ng/ml) (P = 0.554). In addition, a phospho-tyrosine immunoprecipitation and mass spectrometry were used to isolate and identify interferonalpha in canine synovial fluid.
Matrix metalloproteinase and tissue inhibitor of metalloproteinase activity in synovial fluid from horses with post-traumatic osteoarthritis
