Assessment of Serum Interleukin-23 as a Biomarker for Diagnosis and Disease Activity Evaluation in Ankylosing Spondylitis Patients

Ankylosing spondylitis (AS) is an inflammatory arthritis mediated by the immune system. The axial skeleton is the main portion affected by AS. Interleukin-23 is a pro-inflammatory mediator that plays a complex role in the pathophysiology of AS, particularly in bone remodeling and new bone formation. The objective of this study is to determine whether IL-23 plays an effective role in the diagnosis and evaluation of AS activity. A case-control study, involving 30 patients with Ankylosing Spondylitis (AS), 30 patients with chronic back pain (CBP), and 28 healthy individuals. Also, IL-23 and CRP levels were measured for all three groups using an ELISA technique. The study also evaluated the CBC and ESR levels. The IL-23 level in AS, CBP, and healthy control groups were 37.45± 4.59 pg/ml, 50.60± 7.83 pg/ml, and 63.36± 8.04 pg/ml, respectively, with no significant difference between AS group and CBP group (P=0.153), but with a significant difference between AS group and healthy control group (P=0.008). In patients with AS, based on ASDAS-ESR, there was a significant difference in the IL-23 level among the disease activity groups (P=0.017). This study evaluates IL-23 as a diagnostic tool for AS, with the healthy group, which showed an AUC of 0.234, 72.4% sensitivity, and 69% specificity. Furthermore, IL-23 was assessed as a diagnostic tool between AS and CBP groups, with an AUC of 0.348, 60% sensitivity, and 57.1% specificity. The findings showed that IL-23 has a significant difference between the AS group and the healthy group, also, it plays a significant role in evaluating disease activity in patients with AS by the ASDAS-ESR index; however, it does not have a diagnostic value and is not involved in the initial diagnosis of AS.