Increased levels of interleukin-33 associated with bone erosion and interstitial lung diseases in patients with rheumatoid arthritis

Objective To analyze the levels of interleukin-33 (IL-33) in the serum of patients with rheumatoid arthritis (RA) and investigated its possible pathophysiological importance. Methods The concentrations of IL-33 and matrix metalloproteinase (MMP)-3 were measured by enzyme-linked immunosorbent assay (ELISA) in the serum of 121 patients with RA and 47 controls. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), and anticyclic citrullinated peptide (anti-CCP) were measured by standard laboratory techniques. Interstitial lung disease (ILD) was identified on high-resolution computed tomography. Disease activity in RA was scored with the Disease Activity Score 28 based on C-reactive protein levels (DAS28-CRP). The bone erosion of RA patients was evaluated by modified Sharp Score (MSS). Results Serum levels of IL-33 and MMP-3 were significantly higher in RA patients than in healthy controls. Significant higher levels of IL-33 were found in CCP-positive group and in patients with ILD. There was positive correlation between the levels of IL-33 and RF. Moreover, there was also positive correlation between IL-33 and MMP-3, MSS. Conclusion These data support the hypothesis that IL-33 may be involved in RA pathogenesis and it may partly contribute to the bone erosion in RA patients.