Dynamic thiol-disulfide homeostasis as an oxidative stress marker in ankylosing and undifferentiated

Background/aim: Seronegative spondyloarthropathies (SpA) are a group of chronic diseases characterized by axial inflammation, oligoarthritis, and enthesitis. Oxidative stress may contribute to a wide range of rheumatologic diseases, including SpA. This prospective case-control study was designed to compare thiol-disulfide levels as a marker of oxidative stress between SpA patients and healthy controls.Materials and methods: A total of 144 patients diagnosed with undifferentiated spondyloarthropathy (USpA, n = 97) or ankylosing spondylitis (AS, n = 47) were included along with 80 healthy controls. Serum native thiol (NT), total thiol (TT), and disulfide (D) levels were measured using the fully automated Erel method. The ratios NT/TT, D/TT, and D/NT were calculated. Thiol-disulfide levels were compared between the SpA groups and the healthy controls.Results: The NT and NT/TT ratios were found to be significantly lower in the SpA group (p < 0.001). The disulfide, D/NT, and D/TT ratios were found to be significantly higher in the SpA group (p < 0.001). In pairwise comparisons between the SpA subgroups, the NT and TT levels were lower in the USpA group than in the AS group (p = 0.021), but serum disulfide levels were higher in the USpA group than in the AS group (p = 0.004). Among the patients with SpA, the group taking antitumor necrosis factor (anti-TNF) had lower TT measurements compared to the group taking conventional disease modifying antirheumatic drugs (DMARD) (p = 0.039).Conclusion: The thiol-disulfide balance is disturbed in favor of disulfide in SpA patients compared to healthy volunteers. Native and total thiol measurements correlate with acute phase reactants and might be used to monitor disease activity. Anti-TNF therapy might control the oxidative degenerative process better than the conventional DMARD in SpA patients.