role of interleukin-1 receptor antagonist in the pathogenesis of arthritis

ABSTRACT

The objectives from this study was to compare serum levels of interleukin-1 receptor antagonist [IL-1Ra] with synovial fluid levels in patients with rheumatoid arthritis [RA] and osteoarthritis [OA], and to correlate the level of the naturally occurring IL-1 inhibitor with indices of disease activity and severity in RA patients. A correlation was also done between IL-1Ra and tumor necrosis factor alpha [TNF-alpha] with knee radiographs in OA patients as a parameter of disease severity. IL-1Ra and TNF-alpha were assessed by Enzyme Linked Immunosorbent Assay [ELISA] in serum and synovial fluids in 20 female patients with RA, 20 female patients with OA and in the serum of 15 controls. We found that IL-1Ra and TNF-alpha concentrations were increased in both RA and OA sera compared with the control group. Although there was no significant difference between the concentration of serum IL-1Ra in RA patients when compared to those with OA, we observed that its mean level were higher in patients with RA. Moreover, IL-1Ra levels were correlated significantly with the levels of ESR, CRP as well as all the clinical parameters of disease activity measured in RA patients. We also found significant correlation between the synovial levels of both IL-1Ra and TNF-alpha in RA when compared to OA patients. The mean level of synovial IL-1Ra in RA patients is about twice that was found in OA patients. Our data reveal a consistent association between IL-1Ra production and disease activity and severity in RA patients. It also reveals a high serum and synovial IL-1Ra and TNF-alpha in OA patients that make us suggest that OA should be considered a disease with a systemic and local inflammatory response. Further studies are needed to determine the association of cytokines and its inhibitors in OA