Background and Aims

Rheumatoid Arthritis (RA) is a chronic immune -mediated disease characterized by pro-inflammatory cytokine production, synovial hypertrophy, cartilage and bone destruction resulting in severe disability. Cytokine-mediated immunity plays a major role in the pathogenesis of RA. Interleukin-33 (IL-33) is a pro-inflammatory cytokine from the IL-1 family that is expressed by tissue damage. IL-33 has been detected in high levels and has profound effects in experimental inflammatory arthritis.

The aim of the present study was to investigate the effect of IL-33 in the serum of RA patients and to evaluate the correlation of serum IL-33 with disease activity, laboratory parameters and clinical manifestations.

Methods

Sixty (44 females, 16 males) RA patients, mean age 43.53(10.88) years diagnosed according to the ACR/EULAR criteria for RA and 40 age/sex-matched healthy controls were enrolled in this study. Information on disease duration, disease severity and activity, comorbidities and medications (conventional disease modifying anti-rheumatic drugs and biological therapies) was collected. Serum levels of Il-33 were measured using an enzyme-linked immunoabsorbent assay (ELISA). Disease activity was assessed by the Disease Activity Score 28 (DAS-28).

Results

Serum Il-33 levels were significantly higher in RA patients compared to controls and correlated with disease severity, DAS28, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor (RF)-IgM, RF-IgG, anticitrullinated peptide antibodies (ACPA), TNFα and IL-6. Serum IL-33 levels decreased significantly in RA patients that had received anti-TNF and IL-6 inhibitors.

Conclusions

IL-33 appears to play a pivotal role in the pathogenesis of RA and could be a new therapeutic target. IL-33 is a reliable biomarker of disease activity and severity..