Plasma interleukin-22 level, variants in interleukin-22 gene polymorphism, and the severity of systemic lupus erythematosus among Egyptian pediatric and adolescents

Objectives Our purpose was to investigate, for the first time, genotypes and alleles distribution of two single nucleotide polymorphisms (SNPs) of interleukin 22 (IL-22) (rs1012356 and rs2227485) in Egyptian pediatric and adolescents with systemic lupus erythematosus (SLE) and to evaluate the plasma IL-22 levels and their association with gene polymorphism and SLE risk and severity. Methods The TaqMan (TM) SNP genotyping assay on a real-time polymerase chain reaction (PCR) system was employed to evaluate the polymorphism's genotypes. Plasma IL-22 levels were determined by using an enzyme-linked immunoabsorbent assay (ELISA). Results The frequencies and genotypes of rs2227485 and rs1012356 in IL-22 between SLE patients and controls also haplotypes formed by the same SNPs revealed no statistically significant difference (p > 0.05). Otherwise, logistic regression analysis revealed that patients carrying rs1012356 "TA + AA" genotype had increased risk for prediction of SLE activity (OR = 1.610, 95% CI = 1.339-2.760, p = 0.034) by lowering plasma IL-22 level. Conclusions Among Egyptian pediatric and adolescents, we confirm a combined model "TA + AA" in rs1012356 (A/T) of IL-22 in regression analysis, as an independent predictor for SLE activity by lowering IL-22 plasma levels. Despite neither SNP rs2227485 A/G in IL-22 gene nor haplotypes formed by the same two SNPs (rs2227485 A/G and rs1012356 A/T) were significantly associated with the clinical and/or laboratory manifestations of SLE.