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

Abstract

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 ( $\text{SMD}=1.61$ , $P<0.00001$ ). 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.