Interleukin-1 induced nitric oxide inhibits sulphation of glycosaminoglycan chains in human articular chondrocytes.
Incubation of human articular cartilage explants with interleukin-1alpha (IL-1alpha) inhibited the rate of [35S]sulphate incorporation into glycosaminoglycan (GAG) chains concomitant with an increase in nitric oxide (NO) production. Measurement of the [35S]sulphate showed that IL-1alpha inhibited the synthesis of both keratan sulphate and chondroitin sulphate (CS) chains to a similar extent. This effect was reversed by the NO synthase inhibitor Nomega-iminoethyl-l-ornithine (l-NIO). Analysis of alkali borohydride cleaved GAG chains showed that IL-1alpha had no effect on their size. Similarly when GAG chains were coupled to xyloside the size of the GAG chains attached to the exogenous acceptor decreased but IL-1alpha had no further effect on hydrodynamic size. IL-1alpha did, however, inhibit [35S]sulphate incorporation into xyloside-linked CS chains. In both experiments l-NIO reversed the inhibitory effect on sulphation. Disaccharide analysis of the [35S]GAG chains showed that IL-1alpha preferentially inhibited sulphation of the 6-sulphated isomer and that l-NIO reversed this effect. Thus, IL-1alpha-induced NO mediates the inhibition of sulphate incorporation and alters the sulphation pattern of newly synthesised GAG chains.
Hickery
M S
MS
Kennedy Institute of Rheumatology, 6 Bute Gardens, Hammersmith, London W6 7DW, UK. mark.hickery@medkem.lu.se
Bayliss
M T
MT
D000328:Adult; D002358:Cartilage, Articular / Q000737:chemistry / Q000378:metabolism*; D019902:Chondrocytes / Q000378:metabolism; D019765:Chondroitin ABC Lyase; D046508:Culture Techniques; D004187:Disaccharides / Q000032:analysis; D006025:Glycosaminoglycans / Q000737:chemistry / Q000378:metabolism*; D006027:Glycosides; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D009952:Ornithine / Q000031:analogs & derivatives / Q000494:pharmacology; D013431:Sulfates / Q000032:analysis
D004187:Disaccharides; D006025:Glycosaminoglycans; D006027:Glycosides; D007375:Interleukin-1; D013431:Sulfates; C020341:glucosaminoglycans; C010807:xylosides; D009569:Nitric Oxide; C065027:N(G)-iminoethylornithine; D009952:Ornithine; D019765:Chondroitin ABC Lyase