Objective :
@EN The cell-cell and cell-extracellular matrix interactions are critical to the embryogenesis, morphogenesis, maintenance of tissue integrity, and function of cells. This interactions are mediated by membrane glycoproteins called adhesion
molecules.
β1-integrins are heterodimeric transmembrane glycopro-teins which play critical roles in the abil;ity of cells to elaborate and maintain extracellular matrix. ICAM-1 is a sialylated glycoprotein and mediates various cell-cell interactions in
immunity
and inflammation.
Articular cartilage consists of chondrocytes embedded in an extensive extracellular matirx. In normal tissue, the chondrocytes actively effect the stable equili-brium between the synthesis and degradation of matrix components, so that a constant
concentration of these components is maintained. In osteoarthritis, the stable equilibrium is disrupted and the rate of loss of proteoglycan exceeds the rat of depositon of newly synthesized moleclues. This equilibrium s influenced by cytokines
and
growth factors such as IL-1, TNF-α, IGF-1 and TGF-β.
Integrins and their ligands may mediated some of the interactions of chondrocytes and cellular matrix, and the cytokines and local growth factors may affect the expression of integrins on chondrocytes. ICAM 1 may mediate interactions with other
cells in
osteoarthritic joint, and also may be modulated by cytokines and growth favtors. The effect of IL-1, TNFD-α, IGF-1 and TGF-β in the expression of β1-integrin (CD29) and ICAM-1(CD54) on chondrocytes was investigated.
@ES Methods :
@EN Cultured chopdrocytes (3rd passages) from 2 osteoarthritc patient were used. Cells wee incubated fro 24hours with and without IL-β1 25U/ml, IL-1 50U/ml, TNF-α 1ng/ml, TNF-α 10ng/ml, IFN-γ100U/ml, IGF-1 10ng/ml, IGF-1 50ng/ml, IGF-1
10ng/ml,
TGF-β 10ng/ml, and TGF-β 30ng/ml. Chondrocytes were stained with monoclonal antibodies against β1-integrin (CD29) and ICAM-1 (CD54), and positve cells were counder the light microspec.
@ES Results :
@EN 1) Cultured chondrocytes readily expressed β1-integrin(82.9%). 2) β1-integrin was down-regulated by IL-1β(75.4%), TNF-α(61.2%), and TGF-β(77.0%), and was slightly up-regulated by IFN-γ(85.0%) and IGF-1(88.9%). 3) ICAM-1 was presented
din
only
18.0% of cells. 4) Expjression of ICAM-1 was readily up-regulated by IL-1β(84.0%) and TNF-α(80.4%), and mildly up-regulated by IFN-γ(33.0%), IGF-1(35.0%), and TGF-β(29.3%).
@ES Conclusion :
@EN The presence of β1-integrin and ICAM-1 on chondrocytes and the modulation of their expression by cytokines and local growth factors suggest that they have important roles in the interaction of chondrocytes with cartilage matrix and the have
important roles in the interaction of chondrocytes with cartilage matrix and with other cells of osteoarthritic joints. Their roles should be elucidated by further researches.
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