Synovial fluid gelatinase concentrations and matrix metalloproteinase and cytokine expression in naturally occurring joint disease in horses

Objectives-To determine concentrations of matrix metalloproteinase (MMP)-2 and -9 in synovial fluid; and mRNA expression of MMP-1, -13, and -3; interleukin[IL]-1 alpha and beta; and tumor necrosis factor(TNF)-alpha in synovial membrane and articular cartilage from horses with naturally occurring joint disease. Sample Population-Synovial fluid (n=76), synovial membrane (59), and articular cartilage (45) from 5 clinically normal horses and 55 horses with joint disease categorized as traumatic (acute [AT] or chronic [CT]), osteochondritis dissecans (OCD), or septic (S). Procedure-Synovial fluid gelatinase concentrations were analyzed, using zymography. Synovial membrane and articular cartilage mRNA expression for MMP-1, -3, and -13, IL-1 alpha and beta, TNF-alpha, type-II collagen, and aggrecan were analyzed, using quantitative reverse transcriptase-polymerase chain reaction. Results-Synovial fluid pro-MMP-2 concentration was significantly higher in diseased joints than normal joints. Septic joints had significantly higher concentrations of pro and active MMP-9. Stromelysin-1 was expressed in greater than or equal to 80% of synovial membrane and articular cartilage samples and was strongly influenced by age. Collagenases were rarely expressed, with MMP-13 expressed only in diseased joints. Interleukin-1 beta expression was significantly higher In all OCD samples and was influenced by age. Tumor necrosis factor-alpha expression was significantly higher in cartilage from joints with AT and OCD. There was no correlation between MMP or cytokines and type-II collagen or aggrecan expression. Conclusions and Clinical Relevance-Matrix metalloproteinase-2 and -3 are abundant in naturally occurring joint disease and normal joints. Interleukin-1 beta and TNF-alpha may be Important in the pathogenesis of OCD. Age affects MMP and IL-1 beta concentrations.