Interleukin-6 Suppression by Different TNF Inhibitors in Rheumatoid Arthritis Patients During Maintenance Therapy

Abstract

in rheumatoid arthritis (RA). Objectives: To evaluate the effect of different TNF inhibitors on plasma IL-6 levels and disease activity in RA patients. Methods: A longitudinal, observational study included 65 adult RA patients receiving TNF inhibitors for at least six weeks in Sulaymaniyah, Iraq, between February and August 2022. Disease activity was assessed using the disease activity score 28 (DAS28). Plasma IL-6 levels, CRP, and ESR were measured at two time points over 14 weeks during maintenance therapy. Results: After 14 weeks, adalimumab lowered IL-6 levels to 31.92 ng/L (0.24), ESR to 15 mm/hr (16.8), and CRP to 8.4 mg/L (26.2). DAS28/ESR was also improved, it went from 4.7 (1.2) to 4.0 (1.3), which was the biggest change. Infliximab decreased IL-6 31.87 ng/L (0.29), ESR 10.1 mm/hr (15.0), and CRP 7 mg/L (13.5), but the smallest improvement was in DAS28/ESR 4.6 (1.6) to 4.5 (1.2). Etanercept exhibited the lowest decrease in IL-6, ESR, and CRP: 31.77 ng/L (0.39), 7.5 mm/hr (6.5), and 4.9 mg/L (4.9), respectively. However, it showed the second-greatest median improvement in DAS28/ESR, from 4·4 (1·8) to 4·0 (1·4). No correlation was found between plasma IL-6 levels and DAS28/ESR at either time point. Conclusion: TNF inhibitors differ in reducing plasma IL-6 levels and DAS28 during maintenance therapy in RA patients. Adalimumab was the most effective in reducing IL-6, CRP, ESR levels, and DAS28.