Pro-inflammatory cytokines in spondyloarthritis: a case-control study.

Objectives: We aimed to determine the discriminative values of pro-inflammatory cytokines to distinguish spondyloarthritis patients from healthy subjects and to assess the association between these cytokines and spondyloarthritis characteristics.
Methods: We conducted a case-control study, including 144 subjects matched for age and sex: 72 spondyloarthritis patients(G1) and 72 controls (G2). The disease activity was assessed using ASDAS-CRP and BASDAI. Structural damage was assessed using BASRI. The levels of interleukin (IL) IL-1, IL-6, IL-8, IL-17, IL-23, and tumor necrosis factor α(TNFα) were measured.
Results: Each group included 57 men. The mean age was 44.84 ± 13.42 years. Except for IL-8, all cytokine levels were significantly higher in patients compared to controls (IL-1: p  = 0.05, IL-6: p  = 0.021, TNFα: p = 0.039, IL-17 and IL-23: p  < 0.001). Cutoff values of IL-17 and IL-23 distinguishing patients in G1 from those in G2 were 17.6 and 7.96 pg/mL, respectively. TNFα level correlated to BASDAI ( p  = 0.029) and BASRI ( p  = 0.002). Multivariate analysis showed that structural damage was associated with the male gender ( p = 0.017), longer disease duration ( p  = 0.038), and high disease activity ( p  = 0.044). Disease activity was associated with longer disease duration ( p  = 0.012) and increased IL-6 levels ( p  = 0.05).
Conclusion: Our study showed that IL-17 was the ablest to distinguish between spondyloarthritis patients and controls, suggesting that IL-17 may be helpful for the diagnosis of spondyloarthritis.