Influence of interleukin-4 gene polymorphisms and interleukin-4 serum level on susceptibility and severity of rheumatoid arthritis in Egyptian population

Background: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease in which interleukin-4 (IL-4) plays an important role. This study aimed to investigate the influence of IL-4 variable number of tandem repeats (VNTRs) and IL-4-590 promoter polymorphisms on RA susceptibility, activity and severity in Egyptian population. Materials and methods: One hundred and seventy-two RA patients and 172 controls were enrolled in this study. IL-4 VNTR and IL-4-590 promoter polymorphisms were genotyped using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Serum IL-4 and anti-cyclic citrullinated peptides (anti-CCPs) antibody concentrations were measured by enzyme linked immunosorbent assay (ELISA). Results: Subjects with IL-4-590 TT genotype were significantly more likely to develop RA. IL-4 VNTR 1/1 genotype, IL-4-590 IT and CT genotypes were significantly more associated with erosive RA and positive anti-CCP antibody. RA severity parameters were significantly increased, while, IL-4 level was significantly decreased in RA patients with IL-4 VNTR 1/1 and IL-4-590 TT genotypes. Only patients with IL-4-590 TT genotype showed a significant increase of all RA activity parameters. Conclusion: IL-4 VNTR and IL-4-590 promoter polymorphisms may be helpful for assessing RA severity in Egyptian population. Moreover, IL-4-590 promoter polymorphism may be associated with increased risk and activity of RA. (C) 2013 Elsevier Ltd. All rights reserved.