CHARACTERIZATION OF GANGLIOSIDES FROM NORMAL AND OSTEOARTHRITIC HUMANARTICULAR-CARTILAGE

Objective. Glycosphingolipids (GSLs) are biologically active molecules in the physiology and pathology of cells. Since changes in GSLs might be associated with the impaired metabolism of articular cartilage in osteoarthritis (OA), we investigated gangliosides from normal and OA h uman cartilage. Methods. OA and control cartilage was obtained from pa tients with hip OA and femoral neck fracture, respectively. Gangliosid es were extracted and quantified by determining their lipid-bound sial ic acid concentration. Major gangliosides were identified by immunodet ection on thin-layer plates, purified by high performance liquid chrom atography, and analyzed for their carbohydrate, fatty acid, and long-c hain base composition. Results. The total ganglioside content of OA ca rtilage was decreased by 40% (per mg of DNA). Major gangliosides, GM3 and GD3, separated into 3 on thin-layer chromatography bands. All were decreased except for the lowest migrating band of GM3, which was incr eased 5-fold. This ganglioside had the same carbohydrate moiety and fa tty acids as the other two, but differed by a long-chain base composed mainly of C20-sphingosine. Conclusion. OA cartilage is characterized by a decrease in all gangliosides except GM3, which demonstrates a lar ge increase in the lowest band. These results indicate that there are changes in the biochemical composition of chondrocyte membranes in OA. The causes and roles of these changes remain to be determined.