Association of Treatment Status with Cytokine and sCTLA-4 Profiles in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is triggered by dysregulated cytokine networks, but the distributional association of conventional synthetic (csDMARDs) and biologic DMARDs (bDMARDs) with circulating mediators has not been fully described. In this study, we aimed to investigate the treatment-associated modulation of TNF-α, IL-17, IL-13, and soluble CTLA-4 (sCTLA-4) in 64 RA patients (untreated, n = 14; csDMARD, n = 32; bDMARD ± csDMARD, n = 18) and 20 controls. ELISA was used to determine the serum levels, and Kruskal–Wallis tests and false discovery rate correction were used to determine the differences between groups, accompanied by DAS28- and CRP-adjusted quantile regression. Group-level analysis demonstrated that the levels of IL-17 were higher in patients treated with csDMARDs and bDMARDs than in the controls (FDR-adjusted p = 0.0009 and