AB0840 DIAGNOSIS VALUE OF INTERLEUKIN 23 IN SPONDYLOARTHRITIS
Authors: L. Kharrat, M. Slouma, A. Tezeghdenti, W. Dkhili, R. Dhahri, E. Ghazouani, I. Gharsallah, L. Metoui, B. Louzir
Journal: Annals of the Rheumatic Diseases (2021)

Background: Interleukin 23 (IL-23) is a pivotal pro-inflammatory cytokine in the Th17/IL-23 axis which became the center of attention in researches during these last decades, especially during spondyloarthritis (1). Objectives: We aimed to study the diagnosis value of IL-23 serum in spondyloarthritis. Methods: We conducted a case-control study, including 144 subjects divided into 2 groups: -G1: 72 patients meeting the Assessment of SpondyloArthritis International Society (ASAS) criteria for spondyloarthritis (SA) -G2: 72 healthy controls matched for age and sex. For each SA patient we collected the following parameters: BASDAI (Bath Ankylosing Spondylitis Disease Activity Index), ASDAS (Ankylosing Spondylitis Disease Activity Score), BASFI (Bath Ankylosing Spondylitis Functional Index), and BASRI (Bath Ankylosing Spondylitis Radiology Index). The IL-23 level was measured using Enzyme-linked immunosorbent assay (ELISA). Erythrocyte Sedimentation rate (ESR) and C-reactive protein (CRP) were also measured. We performed a ROC analysis and computed the air under the curve (AUC) at IL-23 to diagnose SA patients. Statistical analysis was performed using “IBM SPSS Statistics” software version 25. Results: The study included 57 men and 15 women. The mean age was 44.84 ± 13.42 years. The mean age at the onset of the disease was 35.97 ± 12.88 years. The disease duration was 8.54 ± 7.7 years. Seventy-nine per cent of our patients had axial radiographic spondyloarthritis (n=57). Peripheral involvement was found in 45.8% (n=33). Eighteen patients had both axial and peripheral involvement concomitantly. Psoriasis was found in 36.1% of the cases (n=26). The mean BASDAI and ASDAS-CRP were 3.21 ± 1.64 and 3.05 ± 1.51, respectively. The mean was BASFI 3.88 ± 2.69. The mean was BASRI 5.26 ± 4.14. The mean ESR and CRP were 36.74 ± 29.38 mm/hr and 20.45 ± 25.19 mg/dL, respectively. IL-23 level was significantly higher in patients compared to healthy controls (23.1 ± 2.72 pg/mL and 5.02 ± 0.59 pg/mL, respectively, p&lt;0.0001). As shown in Figure 1, the AUC value to distinguish between spondyloarthritis and healthy control was 0.705 (p&lt;0.0001). IL-23 cut-off was 7.96 pg/mL (Sensibility= 69.4%, specificity=98.6%). Figure 1. AUC at IL-23 between SA patients 0.705 (p&lt;0.0001) Nevertheless, no correlation was found between serum IL-23 levels and the following parameters: ESR, CRP, BASDAI, ASDAS-CRP, BASFI and BASRI. Conclusion: As reported to previous studies, our study showed that IL-23 is significantly higher in SA patients (2). Interestingly, IL-23 was able to distinguish between SA patients and healthy controls with a cut-off of 7.96 pg/mL. This finding suggests that IL-23 may be practical for the diagnosis of SA. References: [1]K V, D E. IL-23 Responsive Innate-Like T Cells in Spondyloarthritis: The Less Frequent They Are, the More Vital They Appear [Internet]. Vol. 17, Current rheumatology reports. Curr Rheumatol Rep; 2015 [cité 13 avr 2020]. Disponible sur: https://pubmed.ncbi.nlm.nih.gov/25874346/ [2]Wang X, Lin Z, Wei Q, Jiang Y, Gu J. Expression of IL-23 and IL-17 and effect of IL-23 on IL-17 production in ankylosing spondylitis. Rheumatol Int. sept 2009;29(11):1343-7. Disclosure of Interests: None declared