Consideration of the role of antigenic keratan sulphate reacting to a 1/14/16H9 antibody as a molecular marker to monitor cartilage metabolism in horses

The role of keratan sulphate (KS) as a marker of cartilage metabolism was e valuated by using an in vitro model of equine articular cartilage. Articula r cartilage was harvested from clinically healthy 6-month-old foals (n=3). Chondrocytes were centrifuged and cultured as pellets, Chondrocyte pellets were stimulated by insulin-like growth factor (IGF)-I alpha or interleukin (IL)-1 alpha for 2 weeks. The sulfated glycosaminoglycans (GAG) and antigen ic KS concentrations in the culture media were measured by a 1,9-dimethyl-m ethylene blue (DMMB) colorimetric assay and an inhibition ELISA using a 1/1 4/16H9 antibody, respectively. Concentration of GAG was significantly incre ased in the media of pellets stimulated by both IGF-I alpha and IL-1 alpha. Antigenic KS concentration was significantly increased in those stimulated by IL-1 alpha, while no significant change was found in those stimulated b y IGF-I alpha. A high correlation between GAG and antigenic KS concentratio ns was found in the media of pellets stimulated by IL-1 alpha (r=0.87), but not in those stimulated by IGF-I alpha (r=0.43). The results suggest that the concentration of antigenic KS reacting to 1/14/16H9 mirrors the GAG con centration during the stage of cartilage catabolism, but not during the car tilage anabolic stage. The concentration of antigenic KS reacting to 1/14/1 6H9 antibody in biological fluids could therefore be a useful marker to fur ther understand principally the catabolic and slightly the anabolic process of articular cartilage metabolism.