Evaluation of Expression and Polymorphisms of IL23R Gene (rs1884444, rs6693831) in Ankylosing Spondylitis

Abstract

Ankylosing spondylitis (AS) is a chronic inflammatory disease that can cause significant functional complications by affecting the sacroiliac joints and axial skeleton. The disease is characterized by the formation of new bone structure that gradually leads to ankylosis and disability. Through mounting genetic investigations, it has been shown that IL-23 receptor (IL-23R) gene single nucleotide polymorphisms (SNPs) are associated with ankylosing spondylitis (AS). We undertook the present study to investigate whether SNP (rs1884444) located IL-23R is associated with AS in the Iranian population. Method and material: In this case-control study, a total of 425 patients with AS and 400 ethnically matched healthy controls were recruited. AS patients were confirmed based upon the modified New York Criteria. Peripheral blood mononuclear cells (PBMCs) were isolated from AS patients and control group whole blood and then total RNA and DNA contents of leukocytes were extracted. rs1884444 genotyping was performed by amplification-refractory mutation system (ARMS)–PCR technique on DNA samples. Afterward, a quantitative analysis was conducted through real-time PCR using the SYBR Green PCR Master Mix to assay IL-23R mRNA expression. Finally, the data were statistically analyzed to examine the differences between the patient and control groups. Results: The consequences of genotype investigation from this research didn't show any significant association between the frequency of alleles and the distribution of genotypes of rs1884444 and susceptibility to AS. In addition, the mRNA expression investigation indicated the downregulation expression level of IL-23R in AS patients compared to the control group however, it was not statistically significant (P=0.167). Furthermore, the mRNA expression level of IL-23R was positively correlated with the BASDAI and BASFI scores of the total however, it failed to show any positive correlation with BASMI. No statistically significant correlation was observed between the genotypes of rs1884444 and IL-23R expression (P=0.26).