CHANGES IN SULFATION PATTERNS OF CHONDROITIN SULFATE IN EQUINE ARTICULAR-CARTILAGE AND SYNOVIAL-FLUID IN RESPONSE TO AGING AND OSTEOARTHRITIS

Objectives-To determine effects of aging on sulfation of chondroitin s ulfate (CS) in articular cartilage and synovial fluid from normal equi ne middle carpal joints, and to determine whether CS compositional ana lysis can be used to assess alterations in proteoglycan turnover in de generative cartilage obtained from horses with carpal osteochondral fr actures. Sample Population-Carpal articular cartilage and synovial flu id from 44 cadavers with normal joints and from 16 Thoroughbred raceho rses during routine carpal arthroscopic surgery. Procedure-After papai n/chondroitinase digestion of cartilage, CS disaccharides (unsulfated disaccharide Delta Di0S, and monosulfated disaccharides Delta Di4S and Delta Di6S) were quantified by capillary zone electrophoresis. The CS was purified from synovial fluid chondroitinase digested, and analyze d. The CS nonreducing terminal residues, N-acetylgalactosamine (galNAc ) or glucuronic acid adjacent to a 4-sulfated or 8-sulfated galNAc, we re quantified. Results-In cartilage, the Delta Di6S-to-Delta Di4S rati o increased with age; in degenerative cartilage, this ratio was not si gnificantly different from the normal value. Percentage of Delta DI0S decreased with age and was significantly higher in degenerative than i n normal cartilage. The galNAc4S and galNAc4,6S represented greater th an or equal to 96% of the terminal residues. There was a significant d ecrease in B-sulfation of the terminal residues in degenerative cartil age. Conclusions-6-Sulfation of internal and terminal CS residues incr eased with age. Cartilage degeneration in racehorses was accompanied b y deposition of CS chains with altered sulfation patterns. In normal a nd diseased joints of horses > 2 years old, synovial fluid CS was not indicative of cartilage CS and may represent turnover products of a su bpopulation of proteoglycan within the matrix.