Serum levels of Interleukin 22 and Interleukin 6 decrease after treatment in patients with rheumatoid arthritis

Introduction: Rheumatoid arthritis is characterized by synovium inflammation due to the infiltration of immune cells that secrete Th17 cytokines like IL-22 and IL-6. The dynamics of these cytokines during the treatment remain unknown. The aim of this study was to evaluate the levels of IL-22 and IL-6 serum and synovial fluid (SF) in correlation with different biochemical and clinical parameters and treatment-associated changes. Material and methods: Seventy-seven RA patients and 30 controls were recruited. Thirty patients were evaluated after 3 months of treatment and SF was collected of 12 patients. ESR, CRP, RF, anti-CCP hs, IL-22 e IL-6 were measured. DAS28 was used to assess disease activity and response to treatment followed EULAR criteria. Results: There were not differences in serum IL-22 and IL-6 levels between patients and controls. Cytokine levels decreased after treatment, mainly in responder patients. IL-22 was decreased and IL-6 was increased in SF compared to serum. IL-6 correlated positively with CRP and anti-CCPhs. ESR, CRP and DAS28 were increased in patients with detectable IL-6 compared to those with undetectable IL-6. Conclusion: In patients with detectable serum IL-22 and IL-6 levels before treatment initiation, follow-up of cytokine levels could be an useful additional tool to evaluate treatment response.