IL-17 Patterns in Synovium, Serum and Synovial Fluid from Treatment-naïve, Early Rheumatoid Arthritis Patients

Background: There are actually becoming controversial data regarding the profiles of interleukin-17 (IL-17) in different pathogenical stages of rheumatoid arthritis (RA).

Objectives: To assessing the IL-17 patterns in synovium, serum and synovial fluid from treatment-naïve early RA patients and to identifying potential correlations with disease activity markers and with synovial histopathological profile.

Materials And Methods: Serum samples from 30 treatment-naïve early RA patients were evaluated for C-reactive protein (CRP), erythrocytes sedimentation rate (ESR), rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (anti-CCP). IL-17A levels were also assessed in serum and synovial fluid (SF). Disease activity score (DAS28) calculation was done for all patients. Control serum and SF samples were obtained from 29 patients with osteoarthritis (OA); control synovium specimens were obtained from eight patients with OA and during surgery for knee tear ligaments. Histopathological (Hp) score, immunohistochemical reactivity for IL-17 were also assessed in synovium of early RA patients and controls. Dependencies between serum and synovial profile of IL-17A and the other parameters were statistically tested.

Results: In early RA patients, strong correlations of serum and SF IL-17A levels were found with ESR, CRP, RF, anti-CCP, Hp score and IL-17 synovial immunoreactivity; a good correlation was noted with DAS28 score. Also, strong correlation was noted between serum and SF IL-17A levels.

Conclusions: In early stages of untreated RA, simultaneous IL-17 assessment of serum, SF and synovium might be valuable in defining activity and predictive patterns, given that synovium is highly suggestive for an disease aggressivity and might express specific therapeutically targets.