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- Skioldebrand, E, et al.
(författare)
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Enhanced concentration of COMP (cartilage oligomeric matrix protein) in osteochondral fractures from racing Thoroughbreds
- 2005
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Ingår i: Journal of Orthopaedic Research. - : Wiley. - 1554-527X .- 0736-0266. ; 23:1, s. 156-163
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to correlate the levels of COMP and aggrecan as indicators of tissue damage, in synovial fluid (sf) from carpal joints of acutely lame racehorses, with macroscopical lesions of articular cartilage (OA). osteochondral fractures and ligament tears found at arthroscopy. Sixty-three lame horses [49 Standardbred trotters (STB) and 14 Thoroughbreds (TB)] in conventional training and racing that underwent arthroscopy of their middle carpal or radiocarpal joints were included in the study. Intact as well as fragmented COMP and aggrecan released into the synovial fluid were quantified by western blot analyses and ELISA. The expression of COMP in tissues was estimated by mRNA in situ hybridisation and protein immununolocalisation in cartilage and osteochondral fractures. The concentration of sf-COMP was higher in TB with an osteochondral fracture than in STB with osteochondral fractures and TB and STB with OA. The chondrocytes in middle and deep zones of the articular cartilage of the osteochondral fragments (from a TB) expressed COMP mRNA, in contrast to the cartilage on the opposite side of the fracture where no expression was detected. In the synovial fluid from a joint (TB) with osteochondral fractures only intact COMP was present, whereas, fragmented COMP was more prominent in synovial fluid from a joint with OA. The concentration of sf-aggrecan did not differ between the two breeds, or between different lesions. The increased concentration of sf-COMP in TB with osteochondral fractures, but not in synovial fluid from equine joints with OA, is a novel finding. The results from this study indicate that elevated sf-COMP concentration in the joints of Thoroughbreds may be a useful marker for carpal joint osteochondral fragments.
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- Sodersten, F, et al.
(författare)
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Ultrastructural immunolocalization of cartilage oligomeric matrix protein (COMP) in relation to collagen fibrils in the equine tendon
- 2005
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Ingår i: Matrix Biology. - : Elsevier BV. - 1569-1802 .- 0945-053X. ; 24:5, s. 376-385
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Tidskriftsartikel (refereegranskat)abstract
- The structure and organisation of the extracellular matrix, and in particular the axial alignment of type I collagen fibrils, are essential for the tensile strength of tendons. The resident tenocytes synthesize and maintain the composition of the extracellular matrix, which changes with age and maturation. Other components of the extracellular matrix include less abundant collagen types II, III, V, VI, XII, proteoglycans and glycoproteins. Cartilage oligomeric matrix protein (COMP) is an abundant non-collagenous pentameric glycoprotein in the tendon, which can bind to collagen types I and II. The function of COMP in the tendon is not clear, but it may act as a catalyst in fibrillogenesis. Its concentration changes with age, maturation and load. The present study delineates the ultrastructural distribution of COMP and its correlation to collagen fibril thickness in different compartments in two flexor tendons from horses of different ages (foetus, 8 months, 3 years, 12 years). The immunolabeling for COMP was higher in the superficial digital flexor tendon compared with the deep digital flexor tendon and it increased with the age of the animal, with the highest concentration in the 3-year-olds. Fibril diameter differed between age groups and a more homogenous fibril population was found in the fetal tendons. A positive correlation between high COMP immunolabeling and the percentage of small fibrils (<60 nm) were present in the SDFT. COMP immunolabeling was enriched at the gap region of the collagen fibril. In situ hybridization revealed the strongest expression in tendons from the 3-year-old horses whereas there was no expression in foetal tendon.
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