Changes in molecular expression of aggrecan and collagen types I, II, and X, insulin-like growth factor-I, and transforming growth factor-beta1 in articular cartilage obtained from horses with naturally acquired osteochondrosis.
OBJECTIVE
To determine molecular changes in the expression of insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 (TGF-beta1) in horses with osteochondrosis, and to characterize expression of matrix aggrecan and collagen types I, II, and X in articular cartilage of affected joints.


METHODS
Articular cartilage from affected stifle or shoulder joints of 11 horses with naturally acquired osteochondrosis and corresponding joints of 11 clinically normal horses.


METHODS
Harvested specimens were snap frozen in liquid nitrogen, and total RNA was isolated. Specimens were fixed in 4% paraformaldehyde for histologic examinations. Expression of matrix molecules was assessed by analysis of northern blots and in situ hybridization, using equine-specific cDNA probes and riboprobes, respectively. Expression of IGF-I and TGF-beta1 was assessed by use of noncompetitive quantitative polymerase chain reaction, in situ hybridization, and immunohistochemical analysis.


RESULTS
Cartilage obtained from osteochondrosis lesions had significantly greater expression of IGF-I, compared with normal cartilage. Expression of TGF-beta1 and collagen type I were higher, but not significantly so, in affected tissues. Expression of aggrecan or collagen types II and X did not differ between affected and clinically normal cartilage.


CONCLUSIONS
Increased expression of growth factors and collagen type I was found in cartilage from osteochondrosis lesions. However, this probably reflects a healing response to injured tissue rather than a primary alteration. Therefore, methods aimed at altering concentrations of growth factors in cartilage of growing horses would be unlikely to alter the incidence or progress of the disease.
Semevolos
S A
SA
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Nixon
A J
AJ
Brower-Toland
B D
BD
D053674:Aggrecans; D000818:Animals; D015152:Blotting, Northern / Q000662:veterinary; D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D003094:Collagen / Q000096:biosynthesis* / Q000235:genetics; D016326:Extracellular Matrix Proteins; D018507:Gene Expression Regulation, Developmental; D006734:Horse Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006736:Horses; D007150:Immunohistochemistry / Q000662:veterinary; D017403:In Situ Hybridization / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000235:genetics; D007592:Joint Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D037181:Lectins, C-Type; D010007:Osteochondritis / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D011509:Proteoglycans / Q000096:biosynthesis* / Q000235:genetics; D012313:RNA / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000235:genetics; D053773:Transforming Growth Factor beta1
D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D012313:RNA; D007334:Insulin-Like Growth Factor I; D003094:Collagen