title: Differentiation regulates interleukin-1beta-induced cyclo-oxygenase-2 in human articular chondrocytes: role of p38 mitogen-activated protein kinase.
abstract: Chondrocyte dedifferentiation has been noted in osteoarthritic cartilage, but the contribution of this phenomenon is poorly understood. Interleukin (IL)-1beta, the major pro-inflammatory cytokine found in osteoarthritic synovial fluid, induces the dedifferentiation of cultured articular chondrocytes, whereas E-series prostaglandins (PGE) are capable of inducing cell differentiation. Since PGE(2) synthesis is up-regulated by IL-1beta, we addressed the question of whether the state of chondrocyte differentiation may influence the production of IL-1-induced PGE(2) by modulating cyclooxygenase (COX)-2 expression. Immortalized human articular chondrocytes, (tsT/AC62) cultured in monolayer after passage through alginate matrix (alg+) produced 5-fold greater amounts of PGE(2) than continuous monolayer cultures (alg-) after stimulation with IL-1beta. Moreover, IL-1beta induced COX-2 expression at 0.01 ng/ml in (alg+) cells, whereas a 100-fold higher dose of cytokine was necessary for stimulation in (alg-) cells. SB203580, a selective p38 mitogen-activated protein kinase (MAPK) inhibitor, completely abolished the IL-1beta-induced COX-2 mRNA. Overexpression of p38 MAPK induces a COX-2 reporter, whereas overexpression of dominant negative p38 MAPK represses IL-1beta-induced promoter expression. Interestingly, IL-1beta-induced p38 MAPK activity was greatly enhanced in (alg+) compared with (alg-) cells. Our results suggest that differentiated articular chondrocytes are highly responsive to IL-1beta and that p38 MAPK mediates this response by inducing COX-2 gene expression.
authors.affiliation: UPRES-A CNRS 7079, Université Pierre et Marie Curie, 7 Quai Saint-Bernard, 75252 Paris Cédex 05, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Thomas
authors.forename: Sylvie
authors.initials: S
authors.lastname: Thirion
authors.forename: Lydie
authors.initials: L
authors.lastname: Humbert
authors.forename: Lujian
authors.initials: L
authors.lastname: Tan
authors.forename: Mary B
authors.initials: MB
authors.lastname: Goldring
authors.forename: Gilbert
authors.initials: G
authors.lastname: Béréziat
authors.forename: Francis
authors.initials: F
authors.lastname: Berenbaum
mesh_terms: D000464:Alginates; D002358:Cartilage, Articular / Q000201:enzymology*; D018929:Cell Culture Techniques / Q000379:methods; D002460:Cell Line; D019902:Chondrocytes / Q000201:enzymology*; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D017930:Genes, Reporter; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D053577:Interleukin-1 Receptor Accessory Protein; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics*; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics*; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017472:Receptors, Interleukin-1 / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; C507765:IL1RAP protein, human; D007375:Interleukin-1; D053577:Interleukin-1 Receptor Accessory Protein; D007527:Isoenzymes; D008565:Membrane Proteins; D011506:Proteins; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D020723:Glucuronic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone