Aggrecanase and metalloproteinase-specific aggrecan neo-epitopes are induced in the articular cartilage of mice with collagen II-induced arthritis.
OBJECTIVE
To analyze the roles of two classes of proteinases, 'aggrecanase', and matrix metalloproteinases (MMPs), in chondrodestruction during murine collagen-induced arthritis (CIA).


METHODS
Generation of the 'aggrecanase' neo-epitope (NITEGE373), and the MMP neo-epitope (VDIPEN341) within aggrecan was studied by immunoperoxidase microscopy using specific anti-peptide antibodies in normal and stromelysin-1 (SLN-1) deficient knockout mice with CIA.


RESULTS
High levels of NITEGE373 and VDIPEN341 neo-epitopes were observed in foci within CIA paw articular cartilage exhibiting depletion of glycosaminoglycans, in advance of significant cartilage erosion. The highest concentrations of NITEGE373 and VDIPEN341 labeling were observed and often co-distributed in the chondrocyte pericellular matrix, suggesting that stimulated chondrocytes can synthesize and/or activate both enzymes. Other regions of the cartilage frequently exhibited either NITEGE373 or VDIPEN341 labeling, but not both neo-epitopes simultaneously, suggesting that 'aggrecanase' and MMP cleavages of aggrecan may be generated independently. No detectable differences were observed in expression or distribution of either neo-epitope in SLN-1 knockout versus wild-type mice. In addition, in vitro digestion of joint sections with SLN-1 did not alter the expression of cartilage NITEGE373, while markedly increasing VDIPEN341 labeling. Peripheral nerves and brains of naive mice also exhibited intense anti-NITEGE373 labeling.


CONCLUSIONS
These data indicate that NITEGE373 and VDIPEN341 aggrecan neo-epitopes are sensitive and specific markers of early joint pathology, and are consistent with the hypothesis that SLN-1 does not have 'aggrecanase' activity, and that 'aggrecanase' is distinct from the MMPs which cleave aggrecan at the MMP site.
Singer
I I
II
Department of Inflammation Research, Merck Research Labs., Merck & Co., Inc., Rahway, New Jersey 07065, USA.
Scott
S
S
Kawka
D W
DW
Bayne
E K
EK
Weidner
J R
JR
Williams
H R
HR
Mumford
R A
RA
Lark
M W
MW
McDonnell
J
J
Christen
A J
AJ
Moore
V L
VL
Mudgett
J S
JS
Visco
D M
DM
D053674:Aggrecans; D000818:Animals; D001168:Arthritis / Q000209:etiology / Q000378:metabolism*; D015415:Biomarkers; D058581:Brevican; D002358:Cartilage, Articular / Q000378:metabolism*; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism; D003094:Collagen; D010450:Endopeptidases / Q000276:immunology / Q000378:metabolism*; D000939:Epitopes / Q000378:metabolism; D016326:Extracellular Matrix Proteins; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000378:metabolism; D037181:Lectins, C-Type; D019278:Matrix Metalloproteinase 3 / Q000502:physiology; D008666:Metalloendopeptidases / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism*
C508320:Acan protein, mouse; D053674:Aggrecans; C553057:Bcan protein, mouse; D015415:Biomarkers; D058581:Brevican; D011508:Chondroitin Sulfate Proteoglycans; D000939:Epitopes; D016326:Extracellular Matrix Proteins; D007074:Immunoglobulin G; D037181:Lectins, C-Type; D009419:Nerve Tissue Proteins; D011509:Proteoglycans; D003094:Collagen; D010450:Endopeptidases; D008666:Metalloendopeptidases; D019278:Matrix Metalloproteinase 3; C083641:aggrecanase