Oncostatin M in combination with tumour necrosis factor {alpha} induces a chondrocyte membrane associated aggrecanase that is distinct from ADAMTS aggrecanase-1 or -2.
OBJECTIVE
To determine whether oncostatin M (OSM) + tumour necrosis factor alpha (TNFalpha) induces aggrecanase activity in chondrocyte membranes, to determine the effects of transforming growth factor beta1 (TGFbeta1), interleukin 4 (IL4), and tissue inhibitor of metalloproteinases (TIMPs) on this activity, and to determine whether this activity is due to a known ADAMTS aggrecanase.


METHODS
Aggrecanase activity and ability of agents to prevent membrane associated aggrecanase activity were assessed by Western blotting. Expression of known aggrecanases was measured by real time polymerase chain reaction in bovine nasal and human articular chondrocytes.


RESULTS
Chondrocyte membrane associated aggrecanase activity and increased mRNA expression of ADAMTS-1, -4, -5, and -9, but not ADAMTS-4 or -15, were enhanced after stimulation by OSM+TNFalpha in bovine chondrocytes. This activity was inhibited by TIMP-3. In human chondrocytes, OSM+TNFalpha also enhanced ADAMTS-1 and -4 expression, but not that of other ADAMTSs. TNFalpha alone induced ADAMTS-9 expression, whereas OSM addition caused suppression. Both TGFbeta1 and IL4 blocked membrane associated aggrecanase activity and decreased OSM+TNFalpha-induced expression of ADAMTS-9 in bovine and human chondrocytes. IL4 down regulated ADAMTS-4 mRNA, whereas TGFbeta1 increased this expression in both bovine and human chondrocytes.


CONCLUSIONS
OSM+TNFalpha up regulates membrane associated aggrecanase activity and several ADAMTS aggrecanase mRNAs in chondrocytes. The chondroprotective effects of IL4 and TIMP-3 suggest that they may have therapeutic benefit for aggrecanolysis, whereas the differential inhibitory effects of TGFbeta1 may limit its therapeutic potential. Induced membrane associated aggrecanase activity is distinct from known soluble ADAMTS aggrecanases and merits further investigation.
Hui
W
W
Musculoskeletal Research Group, Medical School, University of Newcastle upon Tyne, Newcastle NE2 4HH, UK.
Barksby
H E
HE
Young
D A
DA
Cawston
T E
TE
McKie
N
N
Rowan
A D
AD
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D053683:Oncostatin M; D010455:Peptides / Q000494:pharmacology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
D004791:Enzyme Inhibitors; C508351:OSM protein, human; D010455:Peptides; D012333:RNA, Messenger; D019717:Tissue Inhibitor of Metalloproteinase-3; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D053683:Oncostatin M; D015847:Interleukin-4; D010450:Endopeptidases; C083641:aggrecanase