Mobilization of fibrinolytic enzymes in synovial fluid and plasma of rheumatoid arthritis and spondyloarthropathy and their relation to radiological destruction

Objective. To study the role of fibrinolytic enzymes in inflammatory joint diseases with different types of joint destruction. Methods. Concentrations of the plasminogen activators pro-urokinase, tissue plasminogen activator, plasminogen activator inhibitors 1 and 2 (PAI-1 and PAI-2), plasminogen, and fibrin split product D-dimer in synovial fluid (SF) and blood plasma of 29 patients with rheumatoid arthritis (RA) were compared with the concentrations of 18 patients with spondyloarthropathy (SpA). Levels of the fibrinolytic components were also related to radiological destruction assessed using the Larsen grading system. Results. Patients with RA had significantly higher PAI-1 antigen levels and PAI-1 activity in SF than patients with SpA. Plasma levels of PAI-1 antigen and D-dimer were significantly higher in RA than in SpA. There was also a tendency of lower tPA activities in SF and plasma of patients with RA. Joint destruction correlated significantly with increasing PAI-1 antigen and with decreasing plasminogen in SF when results from all patients were pooled. A significant negative correlation between plasma PAI-2 antigen and Larsen grade was also found. Conclusion. Our results indicate a possible association between joint destruction and mobilization of fibrinolytic enzymes in SF.