Article Text

Interleukin-7 induced immunopathology in arthritis
  1. S A Y Hartgring,
  2. J W J Bijlsma,
  3. F P J G Lafeber,
  4. J A G van Roon
  1. Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, the Netherlands
  1. Correspondence to:
    J A G van Roon
    Rheumatology and Clinical Immunology (F02.127), University Medical Center Utrecht, P.O. Box 85500, 3508 GA Utrecht, the Netherlands; J.vanRoon{at}


Interleukin (IL)-7 is a potent immunoregulatory cytokine that is detected in joints of patients with rheumatoid and juvenile idiopathic arthritis and which correlates with parameters of disease. Several synovial cell types that play an important role in inflammation and immunopathology, such as macrophages, dendritic cells, and fibroblasts, produce IL-7. IL-7 induces cytokines produced by arthritogenic T cells (for example, interferon γ (IFNγ), IL-17), T cell differentiating factors (for example, IL-12), chemokines capable of attracting inflammatory cells (for example, macrophage induced gene (MIG), macrophage inflammatory protein (MIP)-1α) as well as molecules involved in cell adhesion, migration, and costimulation (for example, lymphocyte function associated antigen (LFA)-1, CD40, CD80). In addition, IL-7 can induce bone loss by stimulating osteoclastogenesis that is dependent on receptor activator of nuclear factor κB ligand (RANKL). IL-7 induces tumour necrosis factor α (TNFα) secretion by T cells and by monocytes after T cell dependent monocyte/macrophage activation. Importantly, induction of both IL-7 and IL-7 induced effects seems to be able to operate independent of TNFα. Together this suggests that IL-7 is an important cytokine in several rheumatic conditions, capable of inducing inflammation and immunopathology. Thus it may be an important target for immunotherapy.

  • IFN, interferon
  • IL, interleukin
  • IL-7Rα, IL-7 receptor-α chain
  • JIA, juvenile idiopathic arthritis
  • MIG, macrophage induced gene
  • MIP, macrophage inflammatory protein
  • NK, natural killer
  • RA, rheumatoid arthritis
  • RANKL, receptor activator of nuclear factor κB ligand
  • Th, T helper
  • TNF, tumour necrosis factor
  • interleukin-7
  • immunopathology
  • T cells
  • macrophages
  • rheumatoid arthritis

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  • Competing interests: none declared

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