A high interleukin 1 receptor antagonist/IL-1beta ratio occurs naturally in knee osteoarthritis
Richette, P.; François, M.; Vicaut, E.; Fitting, C.; Bardin, T.; Corvol, Mïté.; Savouret, J-François.; Rannou, Fçois.
Journal of Rheumatology 35(8): 1650-1654
2008
ISSN/ISBN: 0315-162X PMID: 18597398 Document Number: 619332
Objective. To assess the interleukin 1 receptor antagonist (IL-1Ra)/IL-1 beta ratio in synovial fluid (SF) of patients with knee osteoarthritis (OA) or rheumatoid arthritis (RA) to determine a possible relation between cytokine level and disease activity.Methods. IL-1 beta and IL-1Ra concentrations were measured by ELISA in knee SF from patients with OA (n = 42) or RA (n = 11). For OA patients, pain and disability were assessed by a visual analog scale (VAS) and the Lequesne index. RA disease activity was assessed using the Disease Activity Score 28 Joint Count (DAS28).Results. Patients with OA showed lower median levels of IL-1 beta and IL-1Ra in SF than patients with RA (p < 0.001) but a higher IL-1Ra/IL-1 beta ratio: 1793 (584-6221) versus 773.5 (187.64-1570.5) (p = 0.05). For patients with OA, the IL-1Ra/IL-1 beta ratio was not associated with pain or disability. For patients with RA, the IL-1Ra/IL-1 beta ratio and IL-1Ra and IL-1 beta levels were related to SF white blood cell count.Conclusion. High endogenous IL-1Ra/IL-1 beta ratio occurs in SF from knee OA and does not correlate with pain or Lequesne index. Our results suggest that intraarticular injection of IL-1Ra might be self-limited in patients with knee OA and a naturally high SF ratio.