Effect of biological treatment on the thiol/disulfide parameters in patients with axial spondyloarthritis.

Objective: Aim of this study is to compare the thiol/disulfide variables before treatment, at the 3^rd and 6^th months of biologic treatment in patients with axSpA.

Materials & methods: Consecutive patients with axial spondyloarthritis to whom biologic treatment was initiated in our clinic were enrolled upon consent. Demographics, clinical characteristics, laboratory parameters and treatment agents were collected. Disease activity scores and thiol-disulfide balance parameters were recorded at baseline and 3^rd, 6^th months of treatment. Statistical analyses were performed in all patients and in subgroups of ankylosing spondylitis and non-radiographic axial spondyloarthritis patients.

Results: In all patients, total thiol levels were significantly increased at 6^th month in comparison to baseline values (470.5 ± 74.7 vs 491.9 ± 69.6, p = 0.047). Native thiol levels were increased at 6^th month close to significance (438.9 ± 70.4 vs 458.8 ± 63.7, p = 0.060). Moderately strong negative correlations were observed between native thiol levels and disease activity parameters (BASDAI: p = 0,019; ASDAS-CRP: p = 0,035; ASDAS-ESR: p = 0,030), and between total thiol levels and disease activity parameters (BASDAI: p = 0,031; ASDAS-CRP: p = 0,020; ASDAS-ESR: p = 0,026) at 6^th month evaluation.

Discussion & conclusions: Our results demonstrated oxidative stress reducing effect of biologics in axSpA patients parallel to suppression of disease activity at 6^th month of the treatment.