Determination of MMP‐2 and ‐9 activities in synovial fluid of horses with osteoarthritic and arthritic joint diseases using gelatin zymography and immunocapture activity assays

Summary Reasons for performing study : Matrix metalloproteinases (MMPs)‐2 and ‐9 activities have been found elevated in synovial fluid from various diseased human joints. However, in the horse few data are available. Objectives : To explore the clinical significance of MMPs‐2 and ‐9 activities in synovial fluid of horses with different forms of joint diseases. Methods : Gelatin zymography and MMP‐2 and ‐9 immunocapture activity assays were applied on synovial fluids from control joints and joints with aseptic joint disease (AJD) and septic arthritis (SA). Additionally, MMP‐2 and ‐9 activities were measured in samples from SA to monitor the disease process. Results : Zymographic analysis revealed that samples from AJD and SA contained significantly increased latent MMP‐2 activity compared to controls. Samples from SA showed significantly increased monomeric latent MMP‐9 activity compared with all other affected joints and controls. Trace amounts of MMP‐9 activity, due to the active and dimer form, were detected in samples from SA; however, these bands were absent in samples from AJD and controls. Using immunocapture activity assays, MMP‐2 and ‐9 activities were found to be significantly elevated in joints from SA compared to controls and AJD samples. MMP‐2 activity in samples from AJD was significantly increased compared to controls. Both MMP activities decreased in the joints from SA in the course of successful therapy. Conclusions : Data from zymographic analysis confirmed that MMP‐2 and ‐9 were elevated in equine joint diseases. Immunocapture activity assays have been shown to be suitable for the quantitative determination of MMP‐2 and ‐9 activities in synovial fluid of horses. Both MMP‐2 and ‐9 activities seem to be useful to indicate SA, and MMP‐2 activity might be a suitable marker for AJD. Potential relevance : These findings encourage the potential use of MMPs‐2 and ‐9 as additional aids to clinical investigation. Further work is required to validate the clinical significance of MMP activities in the progress of different joint diseases in horses.