J Rheum Dis 2020; 27(1): 37-44  
Associations Between Circulating Interleukin-17 Levels and Systemic Lupus Erythematosus and Between Interleukin-17 Gene Polymorphisms and Disease Susceptibility: A Meta-analysis
Young Ho Lee, M.D., Ph.D., Gwan Gyu Song, M.D., Ph.D.
Department of Rheumatology, Korea University College of Medicine, Seoul, Korea
Correspondence to: Young Ho Lee http://orcid.org/0000-0003-4213-1909
Division of Rheumatology, Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, 73 Inchon-ro, Seongbuk-gu, Seoul 02841, Korea. E-mail:lyhcgh@korea.ac.kr
Received: September 22, 2019; Revised: October 16, 2019; Accepted: October 16, 2019; Published online: January 1, 2020.
© Korean College of Rheumatology. All rights reserved.

This is a open Access article, which permits unrestricted non-commerical use, distribution, and reproduction in any medium, provided the original work is properly cited.
Objective. To systematically investigate the relationship between circulating interleukin-17 (IL-17) levels and systemic lupus erythematosus (SLE) and associations between polymorphisms in IL17 genes and SLE susceptibility. Methods. We performed a meta-analysis of serum/plasma IL-17 levels in patients with SLE and controls and evaluated the associations between the IL17A rs2275913, IL17F rs763780, and IL17F rs2397084 polymorphisms and IL17F copy number variations (CNVs) and risk of SLE. Results. Thirteen studies focusing on 2,096 patients with SLE and 2,587 controls were included. Our meta-analysis revealed that IL-17 levels were significantly higher in the SLE group than the control group (standardized mean difference=1.045, 95% confidence interval [95% CI]=0.521∼1.568, p<0.001). Subgroup analysis using sample size showed increased IL-17 levels in samples from large (n>100) but not small (n<90) SLE groups. We found no evidence of associations between SLE and the IL17A rs2275913, IL17F rs763780, and IL17F rs2397084 polymorphisms. However, a significant association was found between SLE and IL17F CNVs in a pooled cohort of affected individuals compared to that in pooled controls (odd ratio=3.663, 95% CI=2.466∼5.221, p<0.001). Conclusion. This meta-analysis revealed significantly higher circulating IL-17 levels in patients with SLE and showed evidence of associations between IL17F CNVs and SLE.
Keywords: Interleukin-17, Polymorphism, Systemic lupus erythematosus

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