Assessment of the catabolic effects of interleukin-1beta on proteoglycan metabolism in equine cartilage cocultured with synoviocytes.
OBJECTIVE
To evaluate the effects of interleukin (IL)-1beta on proteoglycan metabolism in equine cartilage explants when cultured in the presence of synoviocytes.


METHODS
Samples of cartilage and synovium collected from the femoropatellar joints of three 2- to 3-year-old horses.


METHODS
3 experimental groups were established: cartilage explants only, synoviocytes only, and cartilage explants-synoviocytes in coculture. In each group, samples were cultured with or without IL-1beta (10 ng/mL) for 96 hours. Glycosaminoglycan (GAG) content of cartilage and medium samples was measured by use of a spectrophotometric assay; RNA was isolated from synoviocytes and cartilage and analyzed for expression of matrix metalloproteinases (MMP)-3 and -13 (cartilage and synoviocytes), aggrecan (cartilage), collagen type IIB (cartilage), and 18S as a control (cartilage and synoviocytes) by use of quantitative PCR assays. Cartilage matrix metachromasia was assessed histochemically.


RESULTS
IL-1beta-induced GAG loss from cartilage was significantly less in cocultures than in cartilage-only cultures. Cartilage aggrecan gene expression was also significantly less downregulated and synoviocyte MMP-3 expression was less upregulated by IL-1beta in cocultures, compared with cartilage- and synoviocyte only cultures. Histochemical findings supported the molecular and biochemical results and revealed maintenance of matrix metachromasia in cocultured cartilage treated with IL-1beta.


CONCLUSIONS
Results suggest that synoviocytes secrete 1 or more mediators that preferentially protect matrix GAG metabolism from the degradative effects of IL-1beta. Further studies involving proteomic and microarray approaches in similar coculture systems may elucidate novel therapeutic targets for the treatment of osteoarthritis.
Gregg
Abigail J
AJ
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Fortier
Lisa A
LA
Mohammed
Hussni O
HO
Mayr
Karen G
KG
Miller
Brian J
BJ
Haupt
Jennifer L
JL
D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006025:Glycosaminoglycans / Q000378:metabolism; D006736:Horses / Q000378:metabolism*; D053583:Interleukin-1beta / Q000494:pharmacology*; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism*; D013582:Synovial Fluid / Q000166:cytology* / Q000187:drug effects; D046509:Tissue Culture Techniques
D053674:Aggrecans; D024043:Collagen Type II; D006025:Glycosaminoglycans; D053583:Interleukin-1beta; D011509:Proteoglycans; D053509:Matrix Metalloproteinase 13; D019278:Matrix Metalloproteinase 3