Objectives: To systematically investigate the relationship between circulating interleukin-17 (IL-17) levels and Behçet's disease (BD) and the associations between polymorphisms in IL17 genes and BD susceptibility.
Methods: We searched the Medline, Embase, and Cochrane databases for relevant articles. We performed a meta-analysis of serum/plasma IL-17 levels in BD patients and controls and evaluated the associations between IL17A rs4711998, rs8193036, and rs2275913 and IL17F rs763780 and rs2397084 polymorphisms and the risk of BD.
Results: Twelve studies, involving 901 patients with BD and 1,131 controls, were included. Our meta-analysis revealed that circulating IL-17 levels were significantly higher in the BD group than in the control group (SMD = 1.422, 95% confidence interval [CI] = 0.689-2.155, p<0.001). Subgroup analysis by data type indicated higher IL-17 levels in the BD group in both the original and calculated data populations. Stratification by publication year revealed significantly lower vitamin D levels in the SSc group in both recent and older publication years. No significant differences in IL-17 levels were observed between the active and inactive disease groups. We found no evidence of associations between BD and IL17A rs2275913, L17F rs763780, or rs2397084 polymorphisms. However, a significant association was found between BD and IL17A rs4711998 and rs8193036 polymorphisms in the pooled cohort of affected individuals compared to that in pooled controls (odds ratio [OR] = 1.347, 95% CI = 1.043-1.741, p<0.001; OR = 0.691, 95% CI = 0.542-0.880, p=0.003).
Conclusions: This meta-analysis revealed significantly higher circulating IL-17 levels in BD patients and showed evidence of associations between IL17A rs4711998 and rs8193036 polymorphisms and BD.