ABSTRACT
To determine the level of soluble urokinase plasminogen activator receptor [suPAR] in the plasma and synovial fluid of rheumatoid arthritis [RA] patients and osteoarthritis [OA] patients in comparison to normal healthy subjects, in order to find out its possible role in the pathogenesis of these diseases and to detect whether it can be used as a marker of disease activity and severity. Our study was conducted on 53 subjects. 23 rheumatoid arthritis [RA] patients, 20 patients having knee osteoarthritis [OA] and 10 healthy subjects served as the control group. suPAR level in plasma and synovial fluid of all subjects was measured by ELISA technique. The mean value of soluble urokinase plasminogen activator receptor [suPAR] in plasma and synovial fluid of RA patients was highly significantly increased in comparison to OA patients and healthy subject [p<0.001]. The mean value of plasma suPAR level was also higher in OA patients than healthy subjects but no significant difference was found between them [p>0.05]. While its value in the synovial fluid was significantly increased in OA patients than healthy subjects. Also, no significant difference was found between plasma and synovial fluid suPAR level in RA, and the control group [p>0.05]. While a highly significant difference in its level was found between them in OA patients. There was a significant positive correlation between plasma and synovial fluid level of suPAR and age, duration of disease and disease severity in RA patients. While no significant correlation was found in RA patients between both plasma and synovial fluid level of suPAR and sex, rheumatoid factor sero reactivity, tenderness, swelling [or any of the clinical data], ESR, disease activity index and type of drug received. Also no significant correlation was found between synovial fluid level of suPAR in OA patients and age, and disease severity. A significant positive correlation was found between plasma and synovial fluid level of suPAR in RA patients. The highly significant in crease in the level of suPAR in both plasma and synovial fluid of RA patients compared to other studied groups and the significant correlation between both plasma and synovial fluid suPAR level and disease severity may clarify its possible role in the pathogenesis of RA and may reflect the destructive and erosive nature of this disease. So suPAR appears to be a useful marker that reflects disease severity in RA patients. Also the significant increase in the synovial fluid suPAR level in OA patients in comparison to the control group suggest that alterations in the PA/PAR system also occur in OA and thus might contribute to the pathogenesis of this disease. Since there was no significant difference in the level of suPAR between plasma and synovial fluid, therefore we suggest measuring plasma suPAR only. Also no correlation was found between plasma and synovial fluid suPAR level and disease activity. This needs further extended studies to confirm this result, as it will determine the value of suPAR as a marker of disease activity