Modified expression of the ADAMTS enzymes and tissue inhibitor of metalloproteinases 3 during human intervertebral disc degeneration.
OBJECTIVE
Intervertebral disc degeneration is linked to loss of extracellular matrix (ECM), particularly the early loss of aggrecan. A group of metalloproteinases called aggrecanases are important mediators of aggrecan turnover. The present study was undertaken to investigate the expression of the recognized aggrecanases and their inhibitor, tissue inhibitor of metalloproteinases 3 (TIMP-3), in human intervertebral disc tissue.


METHODS
Twenty-four nondegenerated and 30 degenerated disc samples were analyzed for absolute messenger RNA (mRNA) copy number of ADAMTS 1, 4, 5, 8, 9, and 15 and TIMP-3 by real-time reverse transcription-polymerase chain reaction. Thirty-six formalin-fixed embedded intervertebral disc samples of varying grades of degeneration were used for immunohistochemical analyses. In addition, samples from 8 subjects were analyzed for the presence of matrix metalloproteinase (MMP)- and aggrecanase-generated aggrecan products.


RESULTS
Messenger RNA for all the aggrecanases other than ADAMTS-8 was identified in intervertebral disc tissue, as was mRNA for TIMP-3. Levels of mRNA expression of ADAMTS 1, 4, 5, and 15 were significantly increased in degenerated tissue compared with nondegenerated tissue. All these aggrecanases and TIMP-3 were also detected immunohistochemically in disc tissue, and numbers of nucleus pulposus cells staining positive for ADAMTS 4, 5, 9, and 15 were significantly increased in degenerated tissue compared with nondegenerated tissue. Aggrecan breakdown products generated by MMP and aggrecanase activities were also detected in intervertebral disc tissue.


CONCLUSIONS
The aggrecanases ADAMTS 1, 4, 5, 9, and 15 may contribute to the changes occurring in the ECM during intervertebral disc degeneration. Targeting these enzymes may be a possible future therapeutic strategy for the prevention of intervertebral disc degeneration and its associated morbidity.
Pockert
Aneta J
AJ
University of Manchester, Manchester, UK.
Richardson
Stephen M
SM
Le Maitre
Christine L
CL
Lyon
Malcolm
M
Deakin
Jonathan A
JA
Buttle
David J
DJ
Freemont
Anthony J
AJ
Hoyland
Judith A
JA
D051722:ADAM Proteins / Q000235:genetics* / Q000378:metabolism; D000071097:ADAMTS1 Protein; D000328:Adult; D053674:Aggrecans / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002358:Cartilage, Articular / Q000378:metabolism; D018628:Gene Dosage; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000378:metabolism / Q000473:pathology; D007405:Intervertebral Disc Displacement / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D012335:RNA, Ribosomal; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics* / Q000378:metabolism
D053674:Aggrecans; D015415:Biomarkers; D012333:RNA, Messenger; D012335:RNA, Ribosomal; C088390:TIMP3 protein, human; D019717:Tissue Inhibitor of Metalloproteinase-3; D051722:ADAM Proteins; D000071097:ADAMTS1 Protein; C103859:ADAMTS1 protein, human