THE EXPRESSION OF IL-1, IL-6, AND TGF-BETA IN THE SYNOVIAL-FLUID OF HORSES WITH SURGICALLY-INDUCED TRANSIENT SYNOVITIS

This study investigates the presence of various cytokines in the synov ial fluid of three horses with surgically-induced synovitis in one ant ebrachiocarpal joint. Synovial fluids were sampled from experimental a nd control joints, preoperatively and at two and 30 days post-operativ ely. Samples were analyzed for interleukin-1 and interleukin-6 bioacti vities with a bioassay, and for transforming growth factor-beta protei n by ELISA. Peak cytokine levels were detected on day two post-synovec tomy, and returned to pre-operative levels by 30 days post-synovectomy (Interleukin-6 in treated joints: day #0; 0.53 +/- 0.2, day #2; 9.8 /- 0.7, day #30; 0.4 +/- 0.2. Transforming growth factor-beta in treat ed joints: day #0; 314 +/- 69, day #2; 1101 +/- 325, day #30; 321 +/- 101). Arthrocentesis alone (i.e. control joints) caused no increase in interleukin-1, interleukin-6 and transforming growth factor-beta leve ls. Interleukin-l and interleukin-6 are thought to both prevent anabol ic and enhance catabolic effects within articular cartilage matrices, whereas it has been proposed that transforming growth factor-beta may have a protective effect on the articular cartilage. This study is the first to document elevated transforming growth factor-beta levels in equine joints.