Influence du chondroïtine sulfate (CS) 
sur l’activité et l’expression de plusieurs isoformes du cytochrome P450 
et de la NADPH P450 réductase

In rabbits, an acute inflammatory reaction induced by the injection of turpentine causes a decrease in cytochrome P450 (CYP) isoforms activity and expression. Chondroitin sulfate (CS) is a Symptomatic Slow Acting Drug for OsteoArthritis (SYSADOA) that elicits anti-inflammatory effects. Since patients take CS over long periods, it was of interest to assess whether CS modulates the activity of cytochrome P450 isoforms. In order to determine the effect of CS on the cytochrome P450, CS was administered in vivo to two animal models, e.g. chronic intake of CS in control rabbits, and chronic intake of CS in rabbits with a CYP down-regulated by an inflammatory reaction (IR).  We used six groups of five rabbits: three to assess the effect of CS on cytochrome P450, one without CS and two receiving orally about 20 mg/kg/day CS for 20 and 30 days; and the remaining three groups of rabbits received turpentine s.c. to generate an aseptic IR (AIR) 48 h before their sacrifice, e.g. days -2, 18 and 28, while exposed to CS for 0, 20 or 30 days, respectively.  In order to verify the presence of inflammation we measured the seromucoids in serum of rabbits with an AIR. Another marker of inflammation, e.g. nitric oxyde  (NO.) production, was assessed in control hepatocytes (Hcont) and in hepatocytes from rabbits with an AIR (Hinfla). In addition, the effect of CS on the nuclear translocation of NF-κB was studied by fluorescence in hepatocytes. Finally, in hepatocytes (both Hcont and Hinfla) the CYP3A6, CYP1A2 and NADPH P450 reductase (NADPH) activity, expression and mRNA were measured. In vitro, the effect of different concentrations of CS, 4S-, 6S- and 4,6S-sulfated disaccharides of CS on the cytochrome P450 was documented. Compared with control rabbits, 20 and 30 days CS did not affect the activity of CYP3A6 and CYP1A2. The AIR increased seromucoids from 8.4±1.6 mg/dl in controls to 95.1±5.7 (p<0.05), as well as the nuclear translocation of NF-κB, and nitric oxide concentrations. The AIR reduced CYP3A6 activity by 62% and CYP1A2 activity by 54%, decrease associated to a reduction in protein expression and in mRNA, e.g. pre-transcriptional down-regulation.  The nuclear translocation of NF-κB was prevented by the administration of CS to rabbits with an AIR, moreover CS impeded the increase of the concentrations of nitric oxide; however CS did not prevent the increase in seromucoids. CS did not prevent the down-regulation of CYP1A2 produced by the inflammatory reaction. CS prevented the time-dependent down-regulation of CYP3A6 in control rabbits and in rabbits with an inflammatory reaction. In this last group, CS restored the amounts of CYP3A6 protein to levels observed in control rabbits, however this increase was independent of the mRNA that remained very depressed. It is noteworthy that even if CS increased CYP3A6 protein, its activity was not recovered. CS did not affect NADPH activity or expression.  Finally, in vitro, CS, 4S-, 6S and 4,6S-sulfated disaccharides of CS did not change the activity and expression of the two isoforms of CYP, and of NADPH. It is concluded that CS does not affect the activity or expression of CYP1A2, nor prevents CYP1A2 AIR-induced down-regulation. However, CS prevents the down-regulation of CYP3A6 time dependently and following the AIR but does not prevent the decrease of catalytic activity.

Keyphrases: cytochrome P450, NADPH-reductase, inflammation, chondroitin sulfate, osteoarthritis