Modified expression of the ADAMTS enzymes and tissue inhibitor of metalloproteinases 3 during human intervertebral disc degeneration

Abstract

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.Conclusion. 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.Chronic low back pain affects Ͼ70% of people at some point in their lives (1), with ϳ10% being chronically disabled. The causes of low back pain are multifactorial, although ϳ40% of all cases involve degeneration of the intervertebral discs (2). During degeneration, the matrix of the intervertebral disc undergoes structural, mechanical, and molecular changes resulting in a loss of demarcation between the outer annulus fibrosus and the inner nucleus pulposus. Additionally, alterations in collagen type and a decrease in proteoglycan content result in loss of tissue integrity, decreased hydration, and inability to withstand load (3). Importantly, the loss of proteoglycan, predominantly aggrecan, is considered to be an early indicator of intervertebral disc degeneration (4). Aggrecan molecules possess long core proteins with many chondroitin sulfate (CS) and keratan sulfate (KS) glycosaminoglycan (GAG) side chains (3). These GAG side chains are polyanionic due to the high content of carboxyl and sulfate groups, and thus they attract and bind water molecules, hydrating the tissue. Degradation

Transcript levels of major MMPs and ADAMTS-4 in relation to the clinicopathological profile of patients with lumbar disc herniation

“…Recently, Pockert et al [24] examined the expression of several members of the ADAMTS family, including ADAMTS-4, in ID samples of patients suffering from degenerative disc disease. Patients with radicular pain were excluded from their study.…”

An understanding of intervertebral disc development, maturation and cell phenotype provides clues to direct cell-based tissue regeneration therapies for disc degeneration

“…Proteoglycan synthesis, particularly aggrecan, also decreases. Concurrently, there is an up-regulation of matrix degrading enzymes, namely MMP (matrix metalloproteinases) -1, -3, -7, -9, -10 and -13 and ADAMTS (A Disintegrin And Metalloproteinase with Thrombospondin Motifs) -1, -4, -5, -9 and -15 [12][13][14].…”

Nerve Growth Factor Is Regulated by Toll-Like Receptor 2 in Human Intervertebral Discs

“…The causes of disc degeneration are multifaceted and not well understood, yet genetics, mechanical load, or traumatic injury to the disc along with several life style choices are known to contribute to the etiologies of disc degeneration (1). During degeneration there is a large increase in catabolic proteases including matrix metalloproteinases (2,3), cathepsins (4,5), high temperature requirement serine protease A1 (HTRA1) (6,7), and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) (8,9). Protease activity degrades the extracellular matrix (ECM), and the generated ECM fragments can potentially function as endogenous danger-associated patterns (DAMPs) also known as "alarmins" (10).…”