Objective: To assess the effect of natural chondroitin sulphate (CS) on the ability of neosynthesised sulphated proteoglycans (PGs) to aggregate in cultured chondrocytes treated with interleukin (IL)1β.
Methods: Primary cultured rabbit articular chondrocytes were treated or not with IL1β alone or with concentrations of CS for 20 h. Neosynthesised PGs were labelled by incorporation of [35SO4]-sulphate and analysed by chromatography on Sepharose 2B columns. Gelatinolytic activity was measured by zymography, and matrix metalloproteinase (MMP)1 mRNA level in chondrocytes underwent real-time PCR. Expression of ADAMTS (for “a disintegrin and metalloproteinase with thrombospondin motifs”) -4 and -5 was analysed by real-time PCR and western blotting.
Results: The production of [35SO4]-labelled PGs was significantly increased with 10 μg/ml CS in the cellular pool rather than in the incubation medium. The addition of CS to IL1β-treated cells inhibited in part the disaggregation of sulphated PGs induced by IL1β. This inhibitory effect of CS is associated with a significant decrease in ADAMTS-5 expression at the mRNA and protein levels. No effect of CS was observed on IL1β-induced gelatinolytic activity, MMP1 mRNA expression or ADAMTS-4 expression.
Conclusion: CS increases the production of functional sulphated PGs in the direct environment of chondrocytes in vitro. This beneficial effect of CS in IL1β-treated cells is associated with decreased expression of ADAMTS-5.
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Funding: This work has been partly supported by INSERM and grants from Laboratoires Genevrier and Fondation Avenir.
Competing interests: None.
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