Correlation of serum and synovial interleukin-1 receptor antagonist with markers of rheumatoid inflammation and joint destruction

الملخص EN

Objective: To measure plasma and synovial fluid levels of interleukin-1 receptor antagonist (IL-1ra), to localize the IL-1ra in the synovial membrane and cartilage/pannus junction, and to find any possible correlation between this naturally occurring IL-1ra and indices of disease activity and joint destruction in rheumatoid arthritis (RA) patients.

Methods: Levels of IL-1ra were measured in the plasma of 40 female RA patients and synovial fluid samples of 15 of them.

Patients were divided into two subgroups according to Larsen Score and were compared to 10 healthy age-matched female controls.

The levels of IL-1ra were measured using quantitative sandwish enzyme-linked immunosorbent assay (ELISA) technique and were correlated with indices of disease activity.

Synovial biopsies were obtained from the knee joints of 12 patients for localization of IL-1ra in the synovial tissue.

Results: Plasma and synovial fluid levels of IL-1ra were significantly higher in both groups of RA patients than in controls.

On comparing group I with II, there wasn’t any significant difference in plasma level of IL-1ra.

But a significant increase in SF IL-1ra levels was found between the 2 subgroups.

There was a significant correlation between serum IL-1ra and the clinical knee scoring, Larsen score, ESR, WBC and platelet counts in subgroup I.

A significant correlation also exsited between serum IL-1ra and the clinical knee scoring, ESR and morning stiffness in subgroup II.

A highly significant correlation was also found between SF IL-1ra and the clinical knee scoring, Larsen score, ESR in both subgroups.

The immunohistochemical results showed that IL-1ra was located mainly in the lining layer (35%) and the endothelial cells (25%), but was rarely detected in the cartilage/pannus junction (<10%).

Conclusion: The present findings indicate that increased levels of IL-1ra, a natural anti-inflammatory acute phase protein, may reflect increased production and activity of IL-1.

These findings confirm the use of this anti-inflammatory molecule as a prognostic marker for joint destruction.