Non-HLA Genetic Polymorphisms of Interleukin-17 and Interleukin-23 Receptor in Behcet’s Syndrome

Abstract

Background:

Behcet’s syndrome (BS) was first described in 1937 as a triad of oral aphthae, genital ulceration, and ocular involvement. It is now recognized as a multisystemic vasculitis that can affect central nervous, gastrointestinal, and cardiovascular systems. Despite extensive research, the etiology of BS remains unclear, and genetic, viral, and environmental factors are thought to contribute to its pathogenesis.

Objective:

This study aimed to investigate the role of interleukin-17 (IL-17) and IL-23 receptor (IL-23R) gene polymorphisms in the etiology of BS and to evaluate their associations with disease activity and clinical features. The IL-23/IL-17 axis was selected due to its pivotal role in T cell–mediated inflammation and vasculitis, which are key pathogenic mechanisms in BS.

Materials and Methods:

This study was conducted at the Ankara University Faculty of Medicine over a 1-year period. A total of 142 patients with BS aged ≥18 years and 140 healthy controls without known rheumatologic or immunological diseases were included. BS was diagnosed according to the International Study Group criteria for Behçet’s disease. Disease activity was assessed using the BS Activity Scale, and patients were classified as having active or inactive disease. Genomic DNA was extracted from peripheral blood samples. IL-17 and IL-23R gene polymorphisms were analyzed using the polymerase chain reaction–restriction fragment length polymorphism method.

Results:

The IL-17 rs2275913 and rs763780 polymorphisms and the IL-23R rs11209032 polymorphism were evaluated. The frequency of the homozygous AA genotype of the rs11209032 was significantly higher in the BS group than in healthy controls (85.9% vs. 17.4%, p < 0.001). Carriage of the A allele was associated with a markedly increased risk of BS; after adjustment for age and sex, carriers had approximately 16-fold higher odds of disease (adjusted odds ratios [OR] = 16.32, 95% confidence intervals [CI]: 9.76–27.12, p < 0.001). No significant differences were observed between BS patients and controls for the IL-17 polymorphisms. Gene polymorphisms were not associated with specific clinical manifestations. However, in the IL-17 rs763780 polymorphism, inactive patients had a higher frequency of the TT genotype compared with the TC genotype (p = 0.03), suggesting a potential role in disease activity rather than susceptibility.

Conclusion:

These findings suggest that IL-17 and IL-23R–related pathways may contribute to the pathogenesis of BS. While the IL-17 variant may be associated with disease activity, the IL-23R rs11209032 polymorphisms show a strong association with disease susceptibility. However, larger studies are needed to confirm these findings and clarify their clinical relevance.