Human articular cartilage and chondrocytes produce hemopoietic colony-stimulating factors in culture in response to IL-1.
The hemopoietic CSF, granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF), are cytokines that mediate the clonal proliferation and differentiation of progenitor cells into mature macrophages and/or granulocytes. We have employed an all-human cell culture system, specific ELISA for GM-CSF and G-CSF, and Northern analysis to investigate whether chondrocytes are a potential source of CSF in rheumatoid disease. We report that human rIL-1 stimulated in a dose-dependent manner the production of GM-CSF and G-CSF by human articular cartilage and chondrocyte monolayers in organ and cell culture, respectively. Increased levels of the CSF Ag were detected after 2 to 8 h stimulation with IL-1, and the optimum dose of IL-1 was 10 to 100 U/ml (0.06 to 0.6 nM IL-1 alpha; 0.02 to 0.2 nM IL-1 beta); neither CSF was detectable in nonstimulated cultures nor in IL-1-stimulated cultures treated with actinomycin D or cycloheximide, indicating the requirement for de novo RNA and protein synthesis. The IL-1-mediated increase in GM-CSF could also be inhibited by the corticosteroid, dexamethasone, but not by the cyclo-oxygenase inhibitor, indomethacin. Although having little effect when tested alone, TNF-alpha and lymphotoxin (TNF-beta) could synergize with IL-1 for the production of GM-CSF. Basic fibroblast growth factor, platelet-derived growth factor, and IFN-alpha and IFN-gamma each had no effect on GM-CSF levels. Results obtained by Northern analysis of chondrocyte total RNA reflected those found for the CSF Ag, namely that CSF mRNA levels were elevated in response to IL-1, but not TNF, and that there was synergy between these two cytokines. We propose that chondrocyte CSF production in response to IL-1, and the concurrent destruction of cartilage by IL-1, could provide a mechanism for the chronic nature of rheumatoid disease.
Campbell
I K
IK
University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Victoria, Australia.
Novak
U
U
Cebon
J
J
Layton
J E
JE
Hamilton
J A
JA
D002356:Cartilage / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002813:Chondrosarcoma / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D016179:Granulocyte Colony-Stimulating Factor / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007375:Interleukin-1; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016179:Granulocyte Colony-Stimulating Factor; D003907:Dexamethasone; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide; D007213:Indomethacin