title: Equine carpal articular cartilage fibronectin distribution associated with training, joint location and cartilage deterioration.
abstract: Processes involved in equine carpal osteochondral injury have not been established. In other species, fibronectin appears important in chondrocyte-matrix interactions, and levels are increased in osteoarthritis. This investigation aimed to (a) describe fibronectin immunoreactivity in the middle carpal joint of 2-year-old Thoroughbreds, (b) determine topographical variations, (c) compare strenuously trained (Group 1) or gently exercised horses (Group 2) and (d) describe sites with early osteoarthritis. Group 1 (n = 6) underwent a 19 week high intensity treadmill training programme. Group 2 (n = 6) underwent 40 min walking until euthanasia. Dorsal and palmar sites on radial, intermediate and third carpal articular surfaces were prepared. Immunohistochemistry was performed using a biotin-streptavidin/peroxidase method. Cross-reactivity of rabbit antihuman fibronectin antiserum with equine fibronectin was confirmed using Western blotting. Results showed: (a) fibronectin was present primarily in pericellular and interterritorial matrix locations, (b) dorsal sites had zonal immunoreactivity compared to palmar sites, (c) Group 1 dorsal radial carpal cartilage had increased superficial staining compared to Group 2 and (d) fibrillated cartilage showed increased intracellular and local matrical immunoreactivity (superficial zone). These findings suggest topographical and exercise-related variations in fibronectin distribution, and indicate equine fibronectin is localised at sites of cartilage degeneration and released into the matrix by chondrocytes in the local area.
authors.affiliation: Centre for Equine Studies, Animal Health Trust, Kentford, Newmarket, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Murray
authors.forename: H C
authors.initials: HC
authors.lastname: Janicke
authors.forename: F M
authors.initials: FM
authors.lastname: Henson
authors.forename: A
authors.initials: A
authors.lastname: Goodship
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D002350:Carpus, Animal / Q000737:chemistry* / Q000276:immunology / Q000473:pathology; D002358:Cartilage, Articular / Q000737:chemistry* / Q000276:immunology / Q000503:physiopathology; D005260:Female; D005353:Fibronectins / Q000032:analysis* / Q000276:immunology; D006734:Horse Diseases / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D006736:Horses; D007150:Immunohistochemistry; D007592:Joint Diseases / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D010003:Osteoarthritis / Q000662:veterinary; D010805:Physical Conditioning, Animal; D011897:Random Allocation
chemical_list: D005353:Fibronectins