Associations between circulating IL-17 levels and rheumatoid arthritis and between IL-17 gene polymorphisms and disease susceptibility: a meta-analysis.

OBJECTIVES

To systematically review evidence regarding the relationship between circulating interleukin-17 (IL-17) levels and rheumatoid arthritis (RA), and associations between polymorphisms in IL-17 genes and RA susceptibility.

METHOD

We performed a meta-analysis of serum/plasma IL-17 levels in patients with RA and controls, and evaluated evidence of associations between the rs2275913, rs3819024, rs4711998 and rs8193036 polymorphisms in and the rs763780 and rs2397084 polymorphisms in and risk for RA.

RESULTS

Fourteen studies including 3118 patients with RA and 2725 controls were included. Our meta-analysis revealed that IL-17 levels were significantly higher in the RA group than in the control group (p=3.1×10). Subgroup analysis using sample size showed increased IL-17 levels in samples from both small (n≤100) and large (n>100) RA groups (p=1.1×10 and p=0.008, respectively). We found evidence of associations between RA and alleles from the rs2275913 and rs763780 polymorphisms in Caucasians (p=0.003 and p=0.037, respectively). In addition, we found an association between RA and alleles of the rs3819024 polymorphism in the pooled RA cohort compared with matched controls (p=0.033). However, no evidence of association was found between the rs2397084, rs4711998 and rs8193036 polymorphisms and RA susceptibility.

CONCLUSIONS

Our meta-analysis revealed significantly higher circulating IL-17 levels in patients with RA, and found evidence of associations between the rs2275913, rs763780 and rs3819024 polymorphisms and pathogenesis of RA.