Exuberant expression of chemokine genes by adult human articular chondrocytes in response to IL-1beta.
OBJECTIVE
To provide a more complete picture of the effect of interleukin-1 beta (IL-1beta) on adult human articular chondrocyte gene expression, in contrast to the candidate gene approach.


METHODS
Chondrocytes from human knee cartilage were cultured in medium containing IL-1beta. Changes in gene expression were analyzed by microarray and reverse transcriptase-polymerase chain reaction analysis. The ability of transforming growth factor beta-1 (TGF-beta1), fibroblast growth factor (FGF)-18, and bone morphogenetic protein 2 (BMP-2) to alter the effects of IL-1beta was analyzed. Computational analysis of the promoter regions of differentially expressed genes for transcription factor binding motifs was performed.


RESULTS
IL-1beta-treated human chondrocytes showed significant increases in the expression of granulocyte colony stimulating factor-3, endothelial leukocyte adhesion molecule 1 and leukemia inhibitory factor as well as for a large group of chemokines that include CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL8, CCL2, CCL3, CCL4, CCL5, CCL8, CCL20, CCL3L1, CX3CL1 and the cytokine IL-6. As expected, the mRNA for matrix metalloproteinase (MMP)-13 and BMP-2 also increased while mRNA for the matrix genes COL2A1 and aggrecan was down-regulated. A subset of chemokines increased rapidly at very low levels of IL-1beta. The phenotype induced by IL-1beta was partially reversed by TGF-beta1, but not by BMP-2. In the presence of IL-1beta, FGF-18 increased expression of ADAMTS-4, aggrecan, BMP-2, COL2A1, CCL3, CCL4, CCL20, CXCL1, CXCL3, CXCL6, IL-1beta, IL-6, and IL-8 and decreased ADAMTS-5, MMP-13, CCL2, and CCL8. Computational analysis revealed a high likelihood that the most up-regulated chemokines are regulated by the transcription factors myocyte enhancer binding factor-3 (MEF-3), CCAAT/enhancer binding protein (C/EBP) and nuclear factor-kappa B (NF-kappaB).


CONCLUSIONS
IL-1beta has a diverse effect on gene expression profile in human chondrocytes affecting matrix genes as well as chemokines and cytokines. TGF-beta1 has the ability to antagonize some of the phenotype induced by IL-1beta.
Department of Orthopaedic Surgery, Washington University School of Medicine at Barnes-Jewish Hospital, St Louis, MO 63110, United States. sandelll@wustl.edu
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Sandell
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Xing
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Franz
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Davies
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Chang
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D001168:Arthritis / Q000235:genetics / Q000378:metabolism*; D002358:Cartilage, Articular / Q000378:metabolism*; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism / Q000494:pharmacology; D019902:Chondrocytes / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000037:antagonists & inhibitors*; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D053583:Interleukin-1beta / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015854:Up-Regulation
D018925:Chemokines; D053583:Interleukin-1beta; D016328:NF-kappa B; D016212:Transforming Growth Factor beta; C113569:fibroblast growth factor 18; D005346:Fibroblast Growth Factors