Chondroitin sulfate modulation of matrix and inflammatory gene expression in IL-1 beta-stimulated chondrocytes - study in hypoxic alginate bead cultures

Objective: To determine the effect of avian chondroitin sulfate (CS) on interleukin-1 beta (IL-1 beta)-induced expression of genes related to catabolic, anabolic and inflammatory aspects in chondrocytes cultured in hypoxic alginate beads. Design: Articular chondrocytes from bovine metacarpal joint were isolated and cultured in alginate beads, using low oxygen atmosphere (5% O-2). After 1-week exposure to CS (1, 10 and 100 mu g/ml), they were treated by recIL-1 beta (10 ng/ml) for 24 or 48 h, in the presence of CS. RNA was extracted and used to determine, by quantitative reverse transcription-polymerase chain reaction, the steady-state levels of mRNAs encoding several genes related to anabolic, catabolic and inflammatory aspects. Glycosaminoglycan (GAG) synthesis was also assayed by S-35-sulfate incorporation. Results: CS decreased IL-1 beta-incluced expression of matrix metalloproteases-1, -3 and -13 and aggrecanases-1 and -2. It slightly enhanced the aggrecan core protein mRNA and the GAG synthesis. Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA levels were found to be reduced by CS treatment. However, no CS-induced decrease of NO was observed in IL-1 beta-treated chondrocytes, whereas prostaglandin E-2 production was diminished in correlation with the COX-2 mRNA amounts. Furthermore, CS was capable of counteracting IL-1 beta-depressed expression of transforming growth factor-beta (TGF-beta) receptors. Conclusions: CS can repress expression of genes encoding proteolytic enzymes involved in cartilage degradation. It also inhibits IL-1 beta-induced expression of the pro-inflammatory genes iNOS and COX-2 and restores TGF-beta receptors I and II (TGF-beta RI and RII) mRNA levels. These data suggest that CS may exert both chondroprotective and anti-inflammatory limited effects on articular cartilage that could have longterm beneficial action on the osteoarthritic process. (c) 2007 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.