Objective: To assess the effect of natural chondroitin sulfate (CS) on the ability of neosynthesized sulfated proteoglycans (PGs) to aggregate in cultured chondrocytes treated with IL-1ß.
Design: Primary cultured rabbit articular chondrocytes were treated or not with IL-1 alone or with concentrations of CS for 20 h. Neosynthesized PGs were labeled by incorporation of [35SO4]-sulfate and analyzed by chromatography on Sepharose 2B columns. Gelatinolytic activity was measured by zymography, and MMP1 mRNA level in chondrocytes underwent real-time PCR. ADAMTS-4 and -5 expression was analyzed by real-time PCR and western blotting.
Results: The production of [35SO4]-labeled PGs was significantly increased with 10 μg/ml CS in the cellular pool rather than in the incubation medium. The addition of CS to IL-1ß-treated cells inhibited in part the disaggregation of sulfated PGs induced by IL-1ß. This inhibitory effect of CS is associated with a significant decrease in ADAMTS 5 expression, at both the mRNA and protein levels. No effect of CS was observed on IL-1ß-induced gelatinolytic activity, MMP1 mRNA expression or ADAMTS4 expression.
Conclusion: CS increases the production of functional sulfated PGs in the direct environment of chondrocytes in vitro. This beneficial effect of CS in IL-1ß-treated cells is associated with decreased expression of ADAMTS 5.
- chondroitin sulfate
- proteoglycan aggregation