Synovial fluid chondroitin and keratan sulphate epitopes, glycosaminoglycans, and hyaluronan in arthritic and normal knees.

OBJECTIVES: To determine concentrations of chondroitin sulphate (CS) and keratan sulphate (KS) epitopes, glycosaminoglycans (GAGs) and hyaluronan (HA) in knee synovial fluid (SF) from normal subjects and patients with osteoarthritis (OA) or rheumatoid arthritis (RA), to test whether these variables may be used as markers of the OA process. METHODS: OA was subdivided into large joint OA (LJOA), nodal generalised OA (NGOA), and OA with calcium pyrophosphate crystal deposition (CPA). Clinical assessment of inflammation (0-6) was undertaken on OA and RA knees. Knee SF was examined by enzyme linked immunosorbent assay for: CS epitopes, using monoclonal antibodies 3-B-3 and 7-D-4; KS epitope using monoclonal antibody 5-D-4; and HA, using biotinylated HA binding region of cartilage proteoglycan. Total sulphated GAGs were measured by dye binding with 1:9 dimethylmethylene blue. RESULTS: Increased SF 3-B-3 concentrations and 3-B-3/GAG ratio were found in OA, compared with RA or normal knees, with higher 3-B-3 and 3-B-3/GAG in LJOA and NGOA than in CPA. SF 7-D-4 and 7-D-4/GAG were reduced in RA, compared with normal and OA; SF 5-D-4 was reduced in OA compared with normal. GAG and HA concentrations were decreased in both OA and RA. No correlations with radiographic scores were observed, but SF 7-D-4 was lower in 'inflamed' compared with 'non-inflamed' RA and OA knees. In patients with bilateral samples there were strong correlations between right and left knees for all SF variables. CONCLUSIONS: Changed concentrations of SF CS and KS can be detected in OA with a profile that differs from that seen in RA. Clinical subgrouping and local joint inflammation may influence these measures, supporting different pathogenesis within OA subgroups and requirement for careful patient characterisation in SF studies.

Chondroitin and keratan sulphate epitopes, glycosaminoglycans, and hyaluronan in progressive versus non-progressive osteoarthritis.

OBJECTIVE: To determine if a single time point estimation of chondroitin sulphate (CS) or keratan sulphate (KS) epitopes, hyaluronan (HA), or total glycosaminoglycans (GAG) in knee synovial fluid at time of hospital referral can predict subsequent radiographic progression of knee osteoarthritis. METHODS: Two groups of hospital referred patients with knee osteoarthritis were compared: (1) a "progressive" group (n = 45), showing further reduction in radiographic joint space of at least one grade (0-3) in at least one compartment; and (2) a "non-progressive" group (n = 25) in whom radiographs showed no change during the mean follow up period of 2.3 years (median 2, range 1 to 5 years). Knee synovial fluid obtained at the first visit was examined by ELISA for: CS epitopes, using monoclonal antibodies 3B3 and 7D4; KS epitope, using monoclonal antibody 5D4; and HA, using biotinylated HA binding region of cartilage proteoglycan. Total sulphated GAG were measured by dye binding with 1:9 dimethylmethylene blue. RESULTS: In patients with bilateral synovial fluid data right and left knee values were closely correlated for all variables. There were no significant differences between CS and KS epitopes, HA, total sulphated GAG, or ratios of individual CS or KS epitopes to total GAG, between progressive and non-progressive groups. CONCLUSIONS: Single time point estimation of CS, KS, HA, or total GAG in synovial fluid does not distinguish radiographically progressive and non-progressive knee osteoarthritis patients followed for two years.