The association between G-197A gene polymorphism of IL-17A with changes in protein interaction of IL-17A, levels of urinary IL-17, and degree of lupus nephritis abnormality

Elevated levels of IL-17 in systemic lupus erythematosus (SLE) patients have been reported to be correlated to renal disorders, but the involvement of the G-197A gene polymorphism of IL 17 in lupus nephritis (LN) and the degree of renal abnormality have not been reported. Therefore, the aim of this study was to investigate these associations. This study involved 30 LN patients and 20 healthy control. Levels of uIL-17 were measured by ELISA, while the G-197A gene polymorphisms of IL-17A were examined using polymerase chain reaction (PCR) and sequence analysis. Changes in the protein structure due to G-197A gene polymorphism of IL-17A were analyzed by in silico investigation. In addition, renal biopsies were performed to determine the degree of renal abnormality (classes I–VI). A significant difference was found between LN patients and the control group in term of uIL-17 levels (p = 0.004). However, the G-197A gene polymorphism of IL-17A between LN patients and the control group were not significantly different (p = 0.154). There were no difference in the levels of uIL-17 between patients and control group on G-197A gene polymorphism of IL-17A (p = 0.682). Also, there were no significant differences in G-197A gene polymorphism of IL-17A toward the degree of nephritis (p = 0.300). In silico investigation showed that G197A gene polymorphism of IL-17A resulted in changes of the pattern of IRF-4 binding to the promoter, thereby affecting its activity. In conclusion, the levels of uIL-17 in LN patients were significantly higher than those in the control group, but G-197A gene polymorphism of IL-17A did not cause varying levels of IL-17 and did not influence the degree of renal abnormalities in LN. © 2016, Springer-Verlag London.