Serum levels of IL-17, IL-4, and INFγ in Serbian patients with early rheumatoid arthritis.

Background: Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disease with autoimmune etiology, characterized by synovial inflammation and destruction of joint cartilage and bone. There are controversial data about the profile of interleukin-17 (IL-17A), interleukin-4 (IL-4), and interferon-gamma (INFI³), indicating in some studies the key role of IL-17, while in others the Th1 cytokines. Materials and Methods: Serum samples of 31 early RA patients were evaluated for erythrocytes sedimentation rate (ESR), rheumatoid factor (RF), C-reactive protein (CRP), anti-cyclic citrullinated peptide antibodies (anti-CCP), and for the tested cytokines (IL-17A, IL-4, and INFI³). Disease activity score (DAS28) calculation was done for all patients. Control serum samples were obtained from 29 healthy volunteers. Results: The levels of tested cytokines were significantly higher (IL-17A, p < 0.001; INFI³, p < 0.001; IL-4, p < 0.01) in patients with early RA, compared to the healthy controls. In early RA patients, a strong correlation of serum IL-17A was found with DAS28, ESR, and CRP. Also, significant negative correlation was found between serum INFI³ levels and the DAS28 score, indicating that INFI³ may play a key role in maintaining immune homeostasis in patients with RA. Conclusion: The mean serum IL-17A levels in patients with early RA, corresponded with the disease activity and severity. This might highlight the usefulness of the serum IL-17A level in defining the activity and predictive patterns, for aggressive disease therapy, and it might express specific therapeutically targets. Key words: Early rheumatoid arthritis, IL-17A, IL-4, INFI³