Abstract
BACKGROUND
Rheumatoid Arthritis (RA) is characterized by joint damage, persistent inflammation, and producing autoantibodies. Interleukin 21 (IL-21) and its receptor (IL 21R) have an important function in the pathogenesis of RA. High serum level of IL-21 has been related to RA and disease activity.
AIM
Here, we assessed the relationship of IL-21 polymorphisms and IL-21 serum levels with RA among Egyptians.
METHODS
DNA was separated from peripheral blood of 120 healthy controls and 120 patients with RA and genotyped for two single nucleotide polymorphisms of the IL-21 gene (rs2055979 and rs2221903) using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) technique. IL-21 serum level was assessed by ELISA.
RESULTS
The IL-21 rs2055979 AA genotype and A allele were higher in RA patients than in the control group (p =0.005, OR=2.657, 95% CI=1.333-5.293 and p =0.019, OR=1.932, 95% CI=1.112-3.356 respectively). The serum levels of anti-CCP, IL-21, Rheumatoid factor, C-reactive protein and ESR were higher in RA subjects in comparison to the controls (p <0.0001). Furthermore, IL-21 serum level was higher in AA genotype of RA patients in comparison to the CC and CA genotypes (p <0.001 and 0.041 respectively). The IL21 rs2221903 genotypes and alleles were statistically indifferent between the studied groups.
CONCLUSIONS
IL-21 rs2255979 polymorphism is associated with the susceptibility to RA in Egyptian subjects. Moreover, the elevated IL-21 levels and its association with AA genotype in RA patients indicate its importance in the pathogenesis of RA. This means that IL-21 might be used as genetic marker and would have therapeutic application in RA.