The synovial activation of chondrocytes: evidence for complex cytokine interactions involving a possible novel factor

G. Bandara, C. W. Lin, H. I. Georgescu, C. H. Evans

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Preparations of lapine synovial 'chondrocy-e activating factors' (CAF) were analyzed for the presence of individual cytokines which modulate the production of neutral metalloproteinases (NMPs) and prostaglandin E2 (PGE2) by articular chondrocytes. A combination of different biochemical analyses suggested that synovial fibroblasts secrete IL-1α, which activated chondrocytes directly, bFGF,which potentiated the activity of IL-1, and TGF-β 1, which produced a bivalent response. TGF-β 1 suppressed NMP synthesis by chondrocytes, but enhanced PGE2 synthesis. The IL-1 receptor antagonist protein (IRAP) eliminated chondrocyte activation by IL-1, but only partially inhibited activation by CAF. Thus, CAF may contain a cytokine in addition to IL-1 which activates chondrocytes. This putative additional factor was more thermosensitive than IL-1, and had an apparent molecular weight of approx. 20 000 when estimated by size exclusion chromatography. Of a variety of purified cytokines tested for their ability to induce NMPs in chondrocytes, only IL-1 was active. This favours the possibility that the activity which resists suppression by IRAP reflects the presence of a novel cytokine.

Original languageEnglish (US)
Pages (from-to)309-318
Number of pages10
JournalBBA - Molecular Cell Research
Volume1134
Issue number3
DOIs
StatePublished - Apr 7 1992

Keywords

  • Chondrocyte activating factor
  • Cytokine
  • Interleukin-1
  • Neutral metalloproteinase
  • Receptor antagonist
  • Synoviocyte

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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