Background: Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease that primarily affects joints. Interleukin-37 (IL-37) is an anti-inflammatory cytokine that is known to suppress immune response and inflammation. The objective of this study is to evaluate the correlation between level of IL-37 and RA progression using the disease activity score in 28 joints (DAS-28).
Methods: A total of 87 RA patients were separated into 4 groups based on the DAS28, referred to as the remission, mild, moderate and severe groups. 18 healthy volunteers were also included. Serum level of IL-37 and IL-37 mRNA expression level in peripheral blood mononuclear cells (PBMCs) in each individual participant as well as IL-37 mRNA expression level in synovial cells were assessed to explore their correlation with RA progression.
Results: Serum level of IL-37 and IL-37 mRNA expression levels in both PBMCs and synovial cells were all positively correlated with the severity of RA as reflected by the DAS28. Receiver operating characteristic (ROC) analysis revealed area under curve (AUC) values of 1, 0.5262 and 0.7789 for the three parameters.
Conclusion: Our results suggest that serum IL-37 level and mRNA expression levels of IL-37 in PBMCs and synovial cells are correlated with the severity of RA in a Chinese population.
Keywords: rheumatoid arthritis, interleukin-37, DAS-28, PBMC, synovial cell