Background Cytokines have an important role in the pathogenesis of rheumatoid arthritis (RA). Muskulosckeletalultrassound (MSUS) is a very useful tool in RA clinical management (1). In the last decades, it has been increasingly used in clinical rheumatology practice worldwide as it has demonstrated consistent and reproducible results among trained rheumatologists (2). Although plasma levels of IL-6 have been related to muskulosckeletalultrassound (MSUS) synovitis in early DMARD-naïve RA (3), there are no similar studies in established disease.
Objectives To investigate a possible association of MSUS synovitis and plasma citokines in patients with established RA.
Methods 64 RA patients treated with non-biological DMARDs and 30 healthy controls were included in this prospective cross-sectional study. A blood sample was taken before evaluation of disease activity (DAS28) and ultrasonography (all tests performed in a blinded fashion). MSUS was performed by one of two ultrassound-trained rheumatologists on 10 joints of both hands (wrists, 2nd and 3rd metacarpophalangeal and 2nd and 3rd proximal interphalangeal joints) using high resolution equipment (My Lab 60, Esaote and 18mHZ linear tranducer). Gray scale (GS) and pD (power Doppler) synovitis were evaluated using a semi-quantitative scale (0–3) in individual joints, and their sum (score 10) was calculated. Plasma cytokines (IL-2, IL-4, IL-6, IL-10, IL-17, TNF, IFN-γ, and VEGF) were quantified by flow cytometry (Cytometric Bead Array kit - CBA; BD Biosciences).
Results Levels of all cytokines, excepting VEGF, were significantly higher in RA patients than in controls (P≤0.05). In RA patients, IL-6, but not other cytokines, correlated positively with DAS28 and swollen joint count (P≤0.01), as well as with 10-joint pD score (figure 1), and GS and pD of both wrists (P<0.01 for all tests). In multiple linear regression, the association of IL-6 with 10-joint pD score was mantained even after adjustment for DAS28. On the other hand, there was no correlation of IL-6 with tender joint count, 10-joint GS score, or presence of erosions.
Conclusions To the best of our knowledge, we report here, for the first time, an association of power Doppler sinovitis and plasma IL-6 independently of DAS28 in patients with established rheumatoid arthritis.
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Disclosure of Interest None declared