Serum IL-37 Level Is Associated with Rheumatoid Arthritis and Disease Activity: A Meta-Analysis.

Interleukin-37 (IL-37) inhibits the pathogenesis of rheumatoid arthritis (RA) via downregulating proinflammatory cytokines. Accordingly, we performed an analysis to accurately assess the relationship between serum IL-37 cytokine levels and disease activity of RA. Subgroup analysis and sensitivity analysis were applied to explore the sources of heterogeneity. Correlation coefficient (r) was utilized to evaluate the relationship between IL-37 and disease activity of RA patients. Ten studies were included into the research. Functional analysis revealed elevated serum IL-37 concentrations in RA patients (SMD = 1.61, P < 0.00001). The relationship between serum IL-37 levels and disease activity was statistically significant (C-reactive protein: r = 1.47, P = 0.0002; erythrocyte sedimentation rate: r = 1.55, P < 0.00001; rheumatoid factor: r = 1.40, P = 0.004; tumor necrosis factor⁃α: r = 1.64, P = 0.0003; Disease Activity Score for 28 joints: r = 1.63, P < 0.00001; tender joint count: r = 1.48, P < 0.00001; and swollen joint count: r = 1.52, P = 0.0003), but anti-CCP was not significant (anti-CCP: r = 0.98, P = 0.72). In summary, these data are suggesting that the elevated serum level of IL-37 in RA is positively correlated with the disease activity of RA, suggesting a role for IL-37in the pathogenesis of RA.