title: Ultrasound power Doppler synovitis is associated with plasma IL-6 in established rheumatoid arthritis.
abstract: Cytokines have an important role in the pathogenesis of rheumatoid arthritis (RA). Although plasma levels of IL-6 have been related to musculoskeletal ultrasound (MSUS) synovitis in early DMARD-naïve RA, there are no similar studies in established disease.
  
  
  
  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 ultrasound-trained rheumatologists on 10 joints of both hands. 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.
  
  
  
  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, 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 maintained even after adjustment for DAS28. However, there was no correlation of IL-6 with tender joint count, 10-joint GS score, or presence of erosions.
  
  
  
  We demonstrated an association of inflammatory findings on MSUS and plasma IL-6 independently of DAS28 in established RA.
authors.affiliation: Rheumatology Service, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil; Rheumatology Service, Hospital Nossa Senhora da Conceição - Grupo Hospitalar Conceição (GHC), Brazil. Electronic address: adprado@gmail.com.
authors.forename: Aline Defaveri
authors.initials: AD
authors.lastname: do Prado
authors.affiliation: Rheumatology Service, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Melissa Cláudia
authors.initials: MC
authors.lastname: Bisi
authors.affiliation: Rheumatology Service, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Deise Marcela
authors.initials: DM
authors.lastname: Piovesan
authors.affiliation: Rheumatology Service, Hospital Nossa Senhora da Conceição - Grupo Hospitalar Conceição (GHC), Brazil.
authors.forename: Markus
authors.initials: M
authors.lastname: Bredemeier
authors.affiliation: Laboratory of Immunosenescence, Institute of Biomedical Research, Pontificia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Talita Siara
authors.initials: TS
authors.lastname: Batista
authors.affiliation: Laboratory of Immunosenescence, Institute of Biomedical Research, Pontificia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Laura
authors.initials: L
authors.lastname: Petersen
authors.affiliation: Laboratory of Immunosenescence, Institute of Biomedical Research, Pontificia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Moises Evandro
authors.initials: ME
authors.lastname: Bauer
authors.affiliation: Rheumatology Service, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Inês Guimarães
authors.initials: IG
authors.lastname: da Silveira
authors.affiliation: Rheumatology Department, Pontifícia Universidade Católica de Campinas (PUCCAMP), Brazil.
authors.forename: José Alexandre
authors.initials: JA
authors.lastname: Mendonça
authors.affiliation: Rheumatology Service, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil.
authors.forename: Henrique Luiz
authors.initials: HL
authors.lastname: Staub
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013585:Synovitis / Q000097:blood* / Q000000981:diagnostic imaging*; D018608:Ultrasonography, Doppler
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6
keywords: Cytokines; IL-6; Power Doppler; Rheumatoid arthritis; Ultrasonography