Chondroitin sulphation patterns in synovial fluid in osteoarthritis subsets

Objectives-To determine concentrations of chondroitin sulphate (CS) disacch arides in knee synovial fluid (SF) from normal subjects and patients with o steoarthritis (OA) or rheumatoid arthritis (RA), to test whether these vari ables differ between different diseases and subsets of OA. Methods-OA was subdivided into large joint OA (LJOA), nodal generalised OA (NGOA), and OA with calcium pyrophosphate crystal deposition (CPA), with 25 , 9, and 11 people in each subset respectively. The SF of 13 normal subject s was also volunteered for analysis along with 15 RA patients. Clinical ass essment of inflammation (0-6) was undertaken on OA and RA knees. Concentrat ions of unsaturated CS disaccharides Delta di6S and Delta di4S were measure d by capillary zone electrophoresis. Results-Concentrations of Delta di6S were lower in RA (5.90 ng/ml) and OA ( 13.24 ng/ml) fluids compared with normal (21.0 ng/ml) but no significant di fferences were seen between disease and normal fluids for Delta di4S (about 4-6 ng/ml). The ratio of Delta di6S:Delta di4S were RA<OA<normal subjects (p < 0.001 for all comparisons). The disaccharide concentration values alon g with the ratios are below. Higher Delta di6S:Delta di4S ratios were obtai ned for LJOA and CPA compared with NGOA. Uninflamed knees had lower concent rations of Delta di6S than inflamed knees (p < 0.01). In patients with bila teral samples, there were strong correlations between right and left knees for all SF variables. Conclusions-Altered ratios of CS sulphation patterns occur in OA and within OA subsets. These further justify considering NGOA as a subset with a diff erent aetiopathogenesis.