Background Interleukin (IL) - 23 is one of the of cytokines involved in systemic inflammation. Interaction between this cytokine and its receptor (IL-23R) that plays an important role in pathogenesis of psoriatic arthritis (PsA).
Objectives The present study aimed to assess the associations between polymorphisms within gene coding IL-23R, IL-23 serum levels and disease activity in patients with PsA.
Methods Fifty-two PsA patients (diagnosed by the criteria recommended by CASPAR group) were genotyped for the IL-23R (rs11209026 and rs7530511) polymorphisms. The nuclear factor kappa (NF-kB1 (rs28362491; ins/del)) polymorphism (associated with the promoter activity of this gene and cytokine gene expressions, including IL-23) was also analyzed in PsA patients group. IL-23 serum levels were assessed by ELISA in patients with PsA, and for comparison, 10 healthy individuals. These laboratory data were further related with clinical characteristics of the patients. Disease Activity Score was measured (swollen and tender joints, ESR, CRP) in addition to BASDAI, BASFI, VAS, and PASI scores.
Results Significantly (p<0.05) elevated levels of IL-23 cytokine were observed in PsA patients (126.5 pg/ml) when compared to control group (24.9 pg/ml). Moreover, IL-23 serum levels were associated with the IL-23R rs7530511 polymorphism. Patients carrying the IL-23R T allele characterized with higher concentrations of IL-23 in serum (299.1 vs 86.8, p<0.05). Interestingly, patients with the IL-23R T allele were also more frequently carrying the ins/ins homozygous NF-kB1 genotype (associated with a better promoter activity and higher expression of cytokines) (7/17 vs 4/34, distribution of the T allele among ins/ins vs del allele positive patients, p=0.03). No association was found between for IL-23 levels or IL-23R polymorphisms and disease activity.
Conclusions Patients with PsA characterize with higher serum levels of IL-23 than healthy individuals. IL-23 concentrations in serum of PsA patients are associated with the polymorphism (rs7530511) of IL-23 receptor encoding gene.
Disclosure of Interest None declared