IL-23R gene polymorphisms in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease in which many different genetic variants of functional gene polymorphisms may play a culprit role in the underlying pathogenetic mechanism. The recent studies suggest that interleukin-23 receptor (IL-23R) gene polymorphisms may increase susceptibility to the development of various autoimmune diseases. We aimed to examine the possible relationship of nine single nucleotide polymorphisms (SNPs) in the IL-23R gene to susceptibility to rheumatoid arthritis and their associations with disease characteristics in the South Aegean region of Turkey. We enrolled 100 rheumatoid arthritis patients and age- and sex-matched 96 healthy subjects in the study. After deoxyribonucleic acid (DNA) isolation was performed, a 'Restriction Fragment Length Polymorphism' (RFLP) method was used for the investigation of polymorphisms associated with the IL-23R gene. Allele identification and genotyping were obtained from polymerase chain reaction (PCR) products using gel electrophoresis. Allele frequencies and detected genotypes were compared between groups. All statistical analyses were performed using SPSS 25.0 (IBM SPSS Statistics 25 software (Armonk, NY: IBM Corp.)). Continuous variables were defined by the mean ± standard deviation and categorical variables were defined by number and percent. Logistic Regression Analysis was used for determining which variables affect the presence of RA. Differences between categorical variables were analyzed with Chi-square analysis. Statistical significance was determined as p < 0.05. The mean age was 53.48 ± 11.7 years in the RA group, whereas 52.55 ± 12.7 years in the healthy control group. The genotypes of IL-23R with rs11805303(TT), rs10889677(AA), rs1004819(AA), and rs7530511(CT) polymorphisms were seen more often in RA patients than healthy controls. Having the AA genotype of IL-23R rs1004819 and the CT genotype of Il-23R rs7530511 increase the development risk of RA with a statistical significance (OR: 3.416 p = 0.003 and OR: 4.899 p = 0.0001, respectively). RA patients with the CC genotype of Il-23R with rs11805303, the CC genotype with rs10889677, and the TT genotype with rs2201841 of the IL-23R gene had higher erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels than with other genotypes. RA patients with the CC genotype rs11805303 and the GG genotype rs1004819 of the IL-23R gene had more active disease. Our findings suggest that all of the nine analyzed IL-23R gene polymorphisms are seen more frequently than healthy controls in our study population. Besides, some SNPs were related to higher acute phase reactants and higher disease activity scores.