Cytokine Profiles in Rheumatoid Arthritis: Relationship of TNF-α , IL-17, and IL-13 with Autoantibodies (RF and Anti-CCP) and Clinical Disease Severity

Abstract

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovial inflammation and autoantibody production. This study aimed to assess serum levels of TNF-α , IL-17, and IL-13 in RA patients and to explore their association with disease severity and autoantibody status in comparison to healthy controls. The study involved 67 RA patients and 20 healthy individuals. Patients were initially classified based on autoantibody status (RF-positive vs. RF-negative and anti-CCP-positive vs. anti-CCP-negative), and further categorized into low, moderate, and high disease activity groups. Cytokine levels were measured by ELISA, CRP and RF by turbidimetry, and anti-CCP levels by electrochemiluminescence immunoassay. Disease severity was evaluated using DAS28-ESR. RA patients had significantly higher levels of TNF-α , IL-17, CRP, ESR, and autoantibodies compared to controls (p < 0.05). TNF-α levels were positively associated with RF and anti-CCP levels (p < 0.05). IL-17 levels showed no significant association with RF or anti-CCP status but were substantially elevated in moderate and severe RA stages. TNF-α levels were also higher in severe RA cases. IL-13 levels showed no significant difference between RA patients and controls and did not correlate with disease severity or autoantibody levels, though it was directly related to IL-17. RF demonstrated the highest diagnostic accuracy for RA (AUC = 0.905), followed by CRP (AUC = 0.779) and IL-17 (AUC = 0.753). TNF-α and IL-17 may be involved in the pathophysiology of RA, whereas RF, CRP, and IL-17 have potential diagnostic value. Further studies are required to clarify the role of IL-13 in RA.