IMMUNOLOCALIZATION OF SELECTED CYTOKINES AND PROTEASES IN CANINE ARTICULAR-CARTILAGE AFTER TRANSARTICULAR LOADING

Cytokines and proteases are thought to play a role in the destruction of cartilage and the development of osteoarthritis. The purpose of thi s study was to document chronological involvement of interleukin-1 bet a (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), stromelysin (MM P-3), fibronectin, and alteration in the chondroitin sulphate sulfatio n pattern. Canine patellae underwent a closed-joint impact to induce t he development of osteoarthritis. The animals were killed at 2, 1 2, 2 4. and 52 weeks. 'rhe patellar damage included cracks in the superfici al zone of cartilage and the zone of the calcified cartilage-bone inte rface, vertical step-off fractures in the zone of calcified cartilage, and loss of proteoglycan around the cracks in the deep and superficia l zones of cartilage. With avidin-biotin immunohistochemistry, these s pecimens were stained with antibodies to IL-1beta, TNF-alpha, MMP-3, f ibronectin, and altered proteoglycan sulfate with the monoclonal antib ody 3-B-3. Three of the four specimens obtained at 2 weeks demonstrate d a strong cellular and weak matrix staining pattern for IL-1beta, TNF -alpha, MMP-3. and fibronectin around the cracks in the superficial an d transitional zones of cartilage. No consistent staining pattern was noted in the cracks in the deep zone. None of the specimens obtained a t 12, 24. or 52 weeks stained for these antibodies. No staining for th e abnormal sulfation with the 3-B-3 antibody was evident in any specim en. The specimens obtained at 52 weeks showed healing of the step-off fractures and a filling-in of the proteoglycan loss. This model probab ly reflects the short-term cartilaginous changes in the patella after trauma; thus, only transient elevations in the cytokines and proteases were evident.