Pamidronate effects in horse osteoarthritis: Relationship of clinical score with inflammatory biomarkers in synovial fluid

Introduction: The use of pamidronate in horses with OA could prevent resorptive phenomena associated with joint disease, and may reduce the inflammatory process and resulting pain. Objective was to analyze differences in clinical scores in horses with osteoarthritis before and after the treatment with pamidronate and standardized correlation with the protein profile and inflammatory markers (IL-6, TNF-α, MMP-2 and MMP-9).Materials and methods: Inflammation markers of synovial fluid from clinically healthy horses (clinical score ≤ 4), and patients (n = 5) (clinical score N 5–9) were evaluated basal and days 3, 10 and 21 after treatment. On day 0 and day 2 intravenous pamidronate (90 mg) were applied to the sick horses. IL-6 and TNF-α were assessed by ELISA; MMP-2 and 9 were evaluated by zymography. Changes in synovial fluid protein profile of pre and post treatment were evaluated by SDS-PAGE. Direct BP inhibition on MMP-9 activity in vitro was determined by zymography. Results: IL-6 did not show significant difference, TNF-α; increased at day 21 post treatment, differences were observed between healthy group and “day 3” (p b 0.001) and “untreated patients” (p b 0.01). For MMP-2 p= ns and MMP-9 showed significant individual differences after the second dose And in protein profile study, before and after treatment, no significant differences were observed. Conclusion: Pamidronate reduced MMP-9 activity. Protease was involved in the degenerative and inflammatory processes by degrading the extracellular matrix, but no direct inhibition on MMP-9 occurred. For TNF-α, the increased may be associated with a certain exacerbation of the inflammatory process which can be considered as beneficial to the resolution of chronic arthritis.