Rheumatoid synovial fluid interleukin-17-producing CD4 T cells have abundant tumor necrosis factor-alpha co-expression, but little interleukin-22 and interleukin-23R expression

Arthritis Res Ther. 2010;12(5):R184. doi: 10.1186/ar3152. Epub 2010 Oct 7.

Abstract

Introduction: Th17 cells have been implicated in the pathogenesis of rheumatoid arthritis (RA). The aim of this study was to systematically analyse the phenotype, cytokine profile and frequency of interleukin-17 (IL-17) producing CD4-positive T cells in mononuclear cells isolated from peripheral blood, synovial fluid and synovial tissue of RA patients with established disease, and to correlate cell frequencies with disease activity.

Methods: Flow cytometry was used to analyse the phenotype and cytokine production of mononuclear cells isolated from peripheral blood (PBMC) (n = 44), synovial fluid (SFMC) (n = 14) and synovium (SVMC) (n = 10) of RA patients and PBMC of healthy controls (n = 13).

Results: The frequency of IL-17-producing CD4 T cells was elevated in RA SFMC compared with RA PBMC (P = 0.04). However, the frequency of this population in RA SVMC was comparable to that in paired RA PBMC. The percentage of IL-17-producing CD4 T cells coexpressing tumor necrosis factor alpha (TNFα) was significantly increased in SFMC (P = 0.0068). The frequency of IFNγ-producing CD4 T cells was also significantly higher in SFMC than paired PBMC (P = 0.042). The majority of IL-17-producing CD4 T cells coexpressed IFNγ. IL-17-producing CD4 T cells in RA PBMC and SFMC exhibited very little IL-22 or IL-23R coexpression.

Conclusions: These findings demonstrate a modest enrichment of IL-17-producing CD4 T cells in RA SFMC compared to PBMC. Th17 cells in SFMC produce more TNFα than their PBMC counterparts, but are not a significant source of IL-22 and do not express IL-23R. However, the percentage of CD4 T cells which produce IL-17 in the rheumatoid joint is low, suggesting that other cells may be alternative sources of IL-17 within the joints of RA patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arthritis, Rheumatoid / immunology*
  • Arthritis, Rheumatoid / metabolism
  • Cell Separation
  • Female
  • Flow Cytometry
  • Humans
  • Interleukin-17 / biosynthesis*
  • Interleukins / biosynthesis
  • Male
  • Middle Aged
  • Receptors, Interleukin / biosynthesis
  • Synovial Fluid / chemistry
  • Synovial Fluid / immunology*
  • Synovial Fluid / metabolism
  • Th17 Cells / immunology*
  • Th17 Cells / metabolism
  • Tumor Necrosis Factor-alpha / biosynthesis*

Substances

  • IL23R protein, human
  • Interleukin-17
  • Interleukins
  • Receptors, Interleukin
  • Tumor Necrosis Factor-alpha
  • interleukin-22