Association of interleukin 22 gene polymorphisms and serum IL-22 level with risk of systemic lupus erythematosus in a Chinese population

The aim of this study was to investigate the association between the single-nucleotide polymorphisms (SNPs) of the interleukin 22 (IL-22) gene and systemic lupus erythematosus (SLE) in a Chinese population. Three IL-22 SNPs (rs2227485, rs2227513 and rs2227491) were genotyped using SNaPshot SNP genotyping assays and identified by sequencing in 314 SLE patients and 411 healthy controls. The IL-22 level of serum was assessed by enzyme-linked immunosorbent assay (ELISA) kits. Data were analysed by spss version 17.0 software. We found that rs2227513 was associated with an increased risk of SLE [AG versus AA: adjusted odds ratio (aOR)=224, 95% confidence interval (CI)=122-412, P=0010; G versus A: adjusted OR=218, 95% CI=120-397, P=0011]. Further analysis in patients with SLE showed that the AG genotype and G allele were associated with an increased risk of renal disorder in SLE (G versus A: aOR=309, 95% CI=130-733, P=0011; AG versus AA: aOR=325, 95% CI=135-785, P=0009). In addition, the concentration of IL-22 was significantly lower in the rs2227513 AG genotype compared with AA genotype (P=0028). These results suggest that rs2227513 polymorphism might contribute to SLE susceptibility, probably by decreasing the expression of IL-22.