Cartilage and joint inflammation. Regulation of IL-8 expression by human articular chondrocytes

J Immunol. 1992 Jan 15;148(2):466-73.

Abstract

Injury to cartilage is a recognized sequela of neutrophil activation in arthritic joints. This study examined the possibility that chondrocytes may play a direct role in intraarticular neutrophil activation. We demonstrate that IL-1 beta-stimulated primary and subcultured human articular chondrocytes, express the gene for the potent neutrophil chemotactic and activating cytokine, IL-8. Expression of IL-8 mRNA is also inducible by TNF-alpha and LPS and, to a lesser degree, by the chondrocyte growth factor, transforming growth factor-beta, but not by platelet-derived growth factor, acidic and basic fibroblast growth factor, or epidermal growth factor. Analysis of IL-1 beta-stimulated cartilage organ cultures by in situ hybridization demonstrates that chondrocytes in all zones of cartilage are rapidly induced to express the IL-8 gene in high copy number. Metabolically labeled IL-1 beta-stimulated chondrocytes synthesize IL-8 de novo, which comigrates on SDS-PAGE with IL-8 produced by synovial fibroblasts. Furthermore, the conditioned media of IL-1 beta-stimulated chondrocytes and cartilage organ cultures contain neutrophil chemotactic activity which is completely neutralized by a specific antibody to IL-8, establishing that a bioactive form of IL-8 is the major secreted neutrophil chemotactic factor. By using a specific RIA, we demonstrate that not only IL-1 beta, but also TNF-alpha and LPS can induce abundant IL-8 secretion from chondrocytes. In conclusion, articular chondrocytes are readily inducible to express the IL-8 gene and secrete biologically active IL-8 which can promote neutrophil-mediated inflammation and cartilage destruction.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Arthritis / etiology*
  • Base Sequence
  • Cartilage, Articular / metabolism*
  • Gene Expression Regulation*
  • Humans
  • Interleukin-1 / pharmacology
  • Interleukin-8 / biosynthesis
  • Interleukin-8 / genetics*
  • Lipopolysaccharides
  • Molecular Sequence Data
  • Neutrophils / physiology
  • Organ Culture Techniques
  • RNA, Messenger / analysis
  • Transforming Growth Factor beta / pharmacology
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Interleukin-1
  • Interleukin-8
  • Lipopolysaccharides
  • RNA, Messenger
  • Transforming Growth Factor beta
  • Tumor Necrosis Factor-alpha