Vol. 290, Issue 2, 587-593, August 1999

Inhibition of Interleukin-1-Induced Proteoglycan Degradation and Nitric Oxide Production in Bovine Articular Cartilage/Chondrocyte Cultures by the Natural Product, Hymenialdisine

Alison M. Badger, Michael N. Cook, Barbara A. Swift, Tonie M. Newman-Tarr, Maxine Gowen and Michael Lark

Department of Bone and Cartilage Biology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania

The effects of hymenialdisine (SK&F 108752) were evaluated on interleukin-1 (IL-1)-induced proteoglycan (PG) degradation, PG synthesis, nitric oxide (NO) production, and inducible nitric oxide synthase (iNOS) gene expression in bovine articular cartilage (BAC) and/or cartilage-derived chondrocytes. Cartilage disks from 0- to 3-month-old calves were treated with IL-1 or retinoic acid. PG release was determined by measuring glycosaminoglycan release, and nitrite production was measured as a readout for NO. Inhibition of iNOS gene expression was measured by Northern blot analysis in IL-1-stimulated, cartilage-derived chondrocytes. To measure PG synthesis, chondrocytes were established in alginate beads and treated with hymenialdisine, and then [³⁵S]sulfate incorporation into PGs was determined. Hymenialdisine inhibited IL-1-stimulated PG breakdown in BAC in a dose-related manner with an IC₅₀ of approximately 0.6 µM. Herbimycin, a protein tyrosine kinase inhibitor, also inhibited PG breakdown, whereas RO 32-0432, a protein kinase C inhibitor, had no effect. Both hymenialdisine and herbimycin also were able to inhibit retinoic acid-stimulated PG release. IL-1-stimulated NO production in BAC was inhibited by hymenialdisine and herbimycin at similar concentrations. The effect on iNOS gene expression was determined by Northern blot analysis in chondrocytes grown in monolayer, and inhibition by hymenialdisine was observed with an IC₅₀ of approximately 0.8 µM. In chondrocytes cultured in alginate beads, IL-1 inhibited PG synthesis, whereas hymenialdisine stimulated synthesis at low concentrations (0.6 and 1.25 µM), and higher doses (2.5 µM) were not stimulatory. Compounds with this profile may have utility in the treatment of osteoarthritis.