IGFs and IGF-Binding Proteins in the Synovial Fluid of Patients with Rheumatoid Arthritis and Osteoarthritis

International Journal of Peptide Research and Therapeutics - The progressive damage of human articular cartilage is associated with loss of integrity of its extracellular matrix components. Their...     

Glycoconjugate markers of joint diseases

A number of different types of glycoconjugate are found associated with joint tissue and fluids, comprising glycoproteins, glycolipids and glycosaminoglycans. Oligosaccharide chains of glycoconjugates are degraded by exoglycosidases, and the dominant exoglycosidase found in human blood, synovial fluid, the synovial membrane and chondrocytes of articular cartilage is HEX (N-acetyl-β-hexosaminidase). HEX is localized mostly intracellularly in synovial cells. Serum activity of HEX may be used to monitor the course and efficiency of treatment of Lyme arthritis, and activity of HEX, above 10 μkat/kg of protein in the synovial fluid, suggests rheumatoid disease. There is a shortage of HEX inhibitors able to penetrate synoviocytes, so the development of drugs which inhibit synthesis and/or the activity of HEX will be a promising field for future investigations.     

Profile of Exoglycosidases in Synovial Cell Cultures Derived from Human Synovial Membrane

OBJECTIVE: Determining the activity of lysosomal exoglycosidases in tissue cultures of synoviocytes derived from the knee joints of patients with injured anterior cruciate ligaments (ACL), juvenile idiopathic arthritis (JIA), and rheumatoid arthritis (RA). METHODS: The following exoglycosidases in cultured synoviocytes were analyzed with p-nitrophenyl derivatives of appropriate sugars as substrates: hexosaminidase (HEX) and its isoenzyme A (HEX-A), beta-glucuronidase (GluA), beta-galactosidase (GAL), alpha-mannosidase (MAN), and alpha-fucosidase (FUC). RESULTS: In our cell cultures, fibroblast-like synovial cells (FLS) dominated. In the group of patients with ACL-injuries, and in the groups of patients with JIA and RA, the activity of the investigated exoglycosidases was significantly higher in the intra- rather than in the extracellular compartment. Hexosaminidase was the predominant exoglycosidase. Stimulation of synoviocytes by IL-1beta in cell cultures significantly increased the activity of HEX, HEX-A, and GluA in both compartments, as well as of GAL, MAN, and FUC in the intracellular compartment. Stimulation by IL-1beta rheumatoidal synoviocytes increased by 128-201% the activity of HEX and HEX A in intracellular compartments and 33-72% in extracellular compartment. CONCLUSIONS: The profile of lysosomal exoglycosidases in a cell culture of human synoviocytes is similar, but not identical, to those in the knee joint. Hexosaminidase is the dominant glycosidase in cultured unstimulated and IL-1beta-stimulated human synoviocytes. The HEX inhibitors may be new drugs for the treatment of inflamed knee joints.