Signal transduction pathways involving p38 MAPK, JNK, NFkappaB and AP-1 influences the response of chondrocytes cultured in agarose constructs to IL-1beta and dynamic compression.
OBJECTIVE
To examine whether inhibitors of the MAPK pathways will influence the response of bovine chondrocytes cultured in agarose constructs to IL-1beta and dynamic compression.


METHODS
Dose-response studies were conducted under IL-1beta conditions with either SB203580, SP600125, PDTC or curcumin. In separate experiments, constructs were treated with IL-1beta and an appropriate concentration of inhibitor and subjected to 15% dynamic compression. Nitrite and PGE2 release, 35SO4 and [3H]-thymidine incorporation were subsequently measured using biochemical assays.


RESULTS
All inhibitors reduced the IL-1beta induced nitrite and PGE2 release in a dose-dependent manner. The inhibition of [3H]-thymidine incorporation by IL-1beta was partially reversed with SB203580, SP600125 or curcumin, but not PDTC. In most cases, the inhibitors reduced 35SO4 incorporation with IL-1beta. For the mechanical loading studies, the inhibitors reduced the compression-induced inhibition of nitrite and PGE2 release and restored [3H]-thymidine and 35SO4 incorporation.


CONCLUSIONS
The MAPK, AP-1 and NF-kappaB signalling pathways are involved in the upregulation of NO and PGE2 release by IL-1beta. Dynamic compression stimulates cell proliferation and proteoglycan synthesis in the presence of IL-1beta and/or inhibitors of the MAPKs and NFkappaB and AP-1 signalling pathways. This experimental approach could provide valuable information for the biophysical/pharmacological treatment of OA.
School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS London, UK. t.t.chowdhury@qmul.ac.uk
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Chowdhury
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Salter
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Bader
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Lee
D000818:Animals; D019149:Bioreactors; D002356:Cartilage / Q000378:metabolism; D002417:Cattle; D019902:Chondrocytes / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053583:Interleukin-1beta / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism*; D010003:Osteoarthritis / Q000378:metabolism; D015398:Signal Transduction; D013314:Stress, Mechanical; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D004791:Enzyme Inhibitors; D053583:Interleukin-1beta; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4