title: Evaluation of the role of keratan sulphate as a molecular marker to monitor cartilage metabolism in horses.
abstract: The role of keratan sulphate (KS) as a metabolic marker of cartilage was evaluated using an in vitro model of equine articular cartilage. Articular 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-I alpha (IGF-I alpha) or interleukin-1 alpha (IL-1 alpha) for 2 weeks. The concentrations of sulphated glycosaminoglycans (GAG) and KS in the culture media were measured by a 1,9-dimethyl-methylene blue (DMMB) colorimetric assay and an inhibition enzyme-linked immunosorbent assay using a 1/20/5D4 antibody, respectively. The concentration of GAG was significantly increased both in the media of pellets stimulated by IGF-I alpha and in those stimulated by IL-1 alpha. KS concentration was significantly increased in those stimulated by IL-1 alpha, while no significant change was found in those stimulated by IGF-I alpha. A high correlation between GAG and KS concentrations was found in the media of pellets stimulated by IL-1 alpha (r = 0.84), but not in those stimulated by IGF-I alpha (r = 0.59). The results suggest that the concentration of KS reacting to 1/20/5D4 mirrors the GAG concentration during the stage of cartilage catabolism, but not during the cartilage anabolic stage. The KS concentration in biological fluids could therefore be a useful marker to understand further the cartilage catabolic process. It may also represent some aspects of the cartilage anabolic process.
authors.affiliation: Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan. okumuram@vetmed.hokudai.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Okumura
authors.forename: T
authors.initials: T
authors.lastname: Fujinaga
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D015415:Biomarkers / Q000032:analysis; D002357:Cartilage Diseases / Q000378:metabolism / Q000662:veterinary*; D002358:Cartilage, Articular / Q000378:metabolism*; D019902:Chondrocytes / Q000378:metabolism; D003124:Colorimetry / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis; D006734:Horse Diseases / Q000378:metabolism*; D006736:Horses; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D007375:Interleukin-1 / Q000502:physiology; D007592:Joint Diseases / Q000378:metabolism / Q000662:veterinary*; D007632:Keratan Sulfate / Q000032:analysis*; D008751:Methylene Blue / Q000031:analogs & derivatives / Q000737:chemistry; D017319:Photosensitizing Agents / Q000737:chemistry; D018709:Statistics, Nonparametric
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; D006025:Glycosaminoglycans; D007375:Interleukin-1; D017319:Photosensitizing Agents; D007334:Insulin-Like Growth Factor I; D007632:Keratan Sulfate; D008751:Methylene Blue; C016401:1,9-dimethylmethylene blue