Chondrocyte-mediated breakdown of cartilage.

Chondrocyte-mediated degradation of cartilage was studied using bovine nasal cartilage discs cultured for up to 8 days in the presence or absence of chemically defined agents. Breakdown, assessed quantitatively as proteoglycan released into culture medium and qualitatively by gel filtration of (medium and cartilage) products, was potently stimulated by highly purified interleukin-1 (IL-1), bacterial lipopolysaccharides, and prostaglandin F2 alpha. IL-1 action was abolished by anti-IL-1 antibodies but unaffected by hydrocortisone. LPS-stimulated breakdown was reversibly inhibited by glucocorticoid hormones, indomethacin, and cAMP. In addition to their usefulness in probing chondrocyte degradative pathways, several of these agents may be of pathogenetic and clinical significance.