Abstract
Articular chondrocytes create and maintain articular cartilage and their growth and metabolism are tightly regulated. The insulin-like growth factors (IGFs), and hence the IGF binding proteins (IGFBPs), play a significant, but unclear, role in this regulation. We examined the articular chondrocyte release of IGFBPs under conditions that simulate inflammation. Human chondrocytes were isolated from articular cartilage obtained post-mortem from a three year old female. The cells were grown in serum free conditions in high density monolayers. Interleukin-1 (IL-1), a central mediator of the inflammatory response, was added to a final concentration of 30 ng/ml and cultures incubated for 4, 12, 24, or 48 hours. Conditioned media were analyzed for IGFBPs by Western ligand blotting, autoradiography, and laser densitometry. Conditioned media from unstimulated chondrocytes contained IGFBPs at 22, 27, 38, and 41 kDa and their concentrations increased linearly over 48 hours. The 38/41 kDa doublet has been shown in serum to be IGFBP-3. Conditioned media from the IL-1 stimulated chondrocytes contained the same forms of IGFBP, plus a 34 kDa IGFBP at 48 hours. The rate of accumulation of the IGFBP-3 doublet from the IL-1 treated chondrocytes was 3.1±0.4 (SE) times the rate from the unstimulated chondrocytes (P<0.05). The rates of accumulation of the 22 and 27 kDa bands were not different. IGFBPs are produced by human chondrocytes in vitro, and IL-1 differentially increases the rate of accumulation of IGFBP-3. IGF-1 has profound effects on articular chondrocytes in vitro, and may play a role in articular cartilage disease. The finding that chondrocytes increase the release of an IGFBP in response to the cytokine IL-1 supports this hypothesis.
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Olney, R., Mohtai, M., Wilson, D. et al. INTERLEUKIN-1 DIFFERENTIALLY STIMULATES INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN 3 RELEASE FROM HUMAN ARTICULAR CHONDROCYTES. Pediatr Res 33 (Suppl 5), S52 (1993). https://doi.org/10.1203/00006450-199305001-00295
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DOI: https://doi.org/10.1203/00006450-199305001-00295