EXPRESSION OF DECORIN AND BIGLYCAN BY RABBIT ARTICULAR CHONDROCYTES -EFFECTS OF CYTOKINES AND PHENOTYPIC MODULATION

In this study, the levels of mRNAs coding for aggrecan, decorin and bi glycan in rabbit articular chondrocytes were investigated, using both monolayer and 3D-alginate cultures treated with TGF-beta(1) and IL-1 b eta. The cells were shown to express higher amounts of proteoglycan me ssages, specially the aggrecan, in gels than in monolayers. TGF-beta(1 ) increased aggrecan mRNA in both systems, whereas biglycan message wa s elevated only in alginate. It markedly decreased decorin expression in monolayer, either in primary or passaged cultures. In contrast, IL- 1 beta had a weak inhibitory effect on both decorin and biglycan expre ssion. Subculturing induced a dramatic decrease of aggrecan mRNA, whil e that of decorin augmented. Biglycan expression transiently increased after two passages, whereas it declined in further subcultures. Passa ged chondrocytes transferred to alginate re-expressed high levels of a ggrecan, decorin and biglycan. The data point to the influence of morp hology, proliferative state and environment of the articular chondrocy tes on their biosynthetic responses to cytokines. Although these immat ure cells do not fully reflect the adult chondrocytes present in the c artilage, this study may help in understanding the behaviour of these cells in osteoarticular diseases, where the surrounding extracellular matrix is profoundly altered. (C) 1998 Elsevier Science B.V. All right s reserved.