Isolation and characterisation of a neutral proteinase from the canine intervertebral disc

Expression of proteinase-activated receptor-2 in the intervertebral disc

STUDY DESIGN

Immunohistochemical and biochemical analyses of proteinase-activated receptor-2 (PAR-2) in rat and human intervertebral discs (IVDs).

OBJECTIVES

To examine the expression and function of PAR-2 in rat IVD cells, and to determine if PAR-2 is expressed in human IVDs.

SUMMARY OF BACKGROUND DATA

PAR-2 is a G protein-coupled receptor that contributes to the regulation of inflammatory reactions and the pathophysiology of inflammatory diseases, including arthritis. The expression of PAR-2 in the IVD has not been determined.

METHODS

PAR-2 expression by rat IVD cells and tissues was examined using immunohistochemistry and western blot. Rat anulus fibrosus cells in monolayer culture were used to examine the biologic role of PAR-2 in vitro. The effect of PAR-2-activating peptide (PAR-2AP) on the catabolic cascade was assessed by western blot and real-time PCR. The expression of PAR-2 by human IVD tissues at different stages of degeneration was determined by immunohistochemical analyses.

RESULTS

PAR-2 was expressed by rat IVD cells and in both anulus fibrosus and nucleus pulposus tissues, PAR-2 expression was up-regulated by interleukin-1beta (IL-1beta). PAR-2AP significantly increased the release of IL-1beta into the medium. Although PAR-2AP had no direct effect on matrix metalloproteinase-3 (MMP-3) and MMP-13 mRNA levels, treatment with PAR-2AP significantly up-regulated the mRNA levels of a disintegrin and metalloproteinase with thrombospondin motif-4. The simultaneous administration of PAR-2AP and IL-1beta synergistically up-regulated the mRNA levels of a disintegrin and metalloproteinase with thrombospondin motif-4, MMP-3, and MMP-13. The expression of PAR-2 was identified in human IVD tissues. The number of PAR-2-expressing cells was significantly elevated in advanced stages of IVD degeneration compared with those in early stages of degeneration.

CONCLUSION

Our results demonstrate for the first time that IVD cells express PAR-2. The expression of PAR-2 is regulated by IL-1beta stimulation. PAR-2 activation accelerates the expression of matrix-degrading enzymes. PAR-2 may play an important role in the cytokine-mediated catabolic cascade and consequently may be involved in IVD degeneration.

Protease activity in gut of Daphnia magna: evidence for trypsin and chymotrypsin enzymes

Two major protease activities were present in gut homogenates of the cladoceran crustacean Daphnia magna: (i) a trypsin activity that hydrolysed the synthetic substrate N-benzoyl-dl-arginine p-nitroanilide and was strongly inhibited by N-p-tosyl-lysine chloroketone (TLCK) and 4-(amidinophenyl)methanesulfonyl fluoride (APMSF) and not inhibited by chymostatin; and (ii) a chymotrypsin activity that hydrolysed synthetic chymotrypsin substrates containing more than one amino acid, did not hydrolyse N-benzoyl-l-tyrosine p-nitroanilide, and was strongly inhibited by chymostatin and not by TLCK and APMSF. Both activities had alkaline pH optima (pH 7-10), but were shown to be due to distinct types of proteases. These two enzyme activities accounted for 75-83% of the proteolytic activity of gut contents. Substrate SDS-polyacrylamide gel electrophoresis revealed nine different proteases ranging from 15 to 73 kDa.

The role of inflammation in disk herniation-associated radiculopathy

OBJECTIVE

The causes and physiopathology of low-back pain and acute lumbar radiculopathy remain unclear. A compression of the nerve root by protruded disk has been suggested but explains only partially the physiopathology of radicular pain. This article provides an overview of the role of inflammation in disk herniation-associated radiculopathy.

METHODS

A review of the relevant literature in American and European medical journals was performed.

RESULTS

Several studies have identified inflammatory mediators (phospholipase A2, prostaglandin E2, leukotrienes, nitric oxide, immunoglobulins, pro-inflammatory cytokines such as interleukin [IL]-1alpha, IL-1beta, IL-6, and tumor necrosis factor alpha [TNFalpha]) and autoimmune reaction (macrophages expressing IL-1beta, intercellular adhesion molecules) in disk herniation. An appealing hypothesis is that the leakage of these agents may produce an excitation of the nociceptors, a direct neural injury, a nerve inflammation, or an enhancement of sensitization to other pain-producing substances (such as bradykinin), leading to the nerve root pain. However, the role of these inflammatory mediators in the pathophysiology of lumbar radiculopathy has not been proven. Several findings suggest that this inflammatory response, which occurs in the early stage of disk herniation, is transient. Indeed, most studies of chronic disk herniation samples failed to demonstrate inflammation.

CONCLUSION

Although inflammation may partially explain lumbar radiculopathy, involvement of inflammatory mediators in the physiopathology of disk herniation-associated radiculopathy has not been proven.

Matrix metalloproteinases: the clue to intervertebral disc degeneration?

STUDY DESIGN

A review of the current literature on the role of matrix metalloproteinases in intervertebral disc degeneration.

OBJECTIVE

To detail the characteristics of matrix metalloproteinases (classification, structure, substrate specificity and regulation) and to report previous studies of intervertebral discs.

SUMMARY OF BACKGROUND DATA

Degeneration of the intervertebral disc, a probable prerequisite to disc herniation, is a complex phenomenon, and its physiopathologic course remains unclear. Matrix metalloproteinases probably play an important role but have received sparse attention in the literature.

METHODS

A systematic review of studies reporting a role of matrix metalloproteinases in intervertebral disc degeneration.

RESULTS

In several studies, investigators have reported the presence of proteolytic enzymes from disc culture systems and disc tissue extracts in degenerated human intervertebral discs, especially collagenase-1 (MMP-1) and stromelysin-1 (MMP-3). The matrix metalloproteinases are regulated by specific inhibitors (tissue inhibitors of metalloproteinases, or TIMPS), cytokines (interleukin-1), and growth factors.

CONCLUSIONS

This field of application is of particular interest because conventional treatments are disappointing in chronic low back pain. Clinical trials with specific inhibitors of metalloproteinases are beginning in osteoarthritis.

Mechanical consequences of annular tears and subsequent intervertebral disc degeneration

The relationship between degeneration of the intervertebral disc and changes to its mechanics is unclear. The aim of this study was to examine, in a sheep model, the effect of creating a lesion in the outer, anterior annulus on the mechanics of the intervertebral joint complex and the disc. Forty-one 2-year-old Merino wethers were allocated randomly into a control group or an annular lesion group and additionally to non-survivors which were sacrificed immediately or survivors sacrificed 6 months later. The annular lesion group had incisions made in two non-adjacent intervertebral discs and a plate was secured across the vertebrae at one level. Mechanical tests were performed on specimens consisting of the two vertebrae, the intervening disc and associated ligaments. Stiffness of the specimens was measured in flexion, extension, and in pure torsion. The tests were conducted first on the intact intervertebral joints and then after removal of the zygapophyseal joints and the interspinous and supraspinous ligaments. The results showed that the creation of an annular lesion caused immediate changes to the mechanics of the disc. In torsion, where no axis of rotation was imposed on the joints, there was a clear reduction in stiffness compared with controls. After 6 months the discs in the lesion groups approached the stiffness of the controls. The plates had a marked effect on the stiffness of the joints in flexion and extension, but after 6 months this difference was not apparent. The mechanics of the intact joints were not affected immediately by the lesion but after 6 months they were less stiff than the controls. There was clear evidence of a progressive degenerative response in the nucleus in all discs with a lesion. The addition of a plate to limit movement did not markedly affect this biological response to the injury but there was some evidence that after 6 months there were fewer degenerative changes to the zygapophyseal joints in the plated specimens. Recovery of the mechanical integrity of the disc was more marked in the joints that were plated, supporting the concept that limiting motion of an injured intervertebral disc facilitates a healing response in the annulus.

The serine proteinase inhibitory proteins of the human intervertebral disc: their isolation, characterization and variation with ageing and degeneration

Serine proteinase inhibitory proteins (SPIs) were extracted from human disc tissues using 2 M GuHCl and subjected to CsCl density gradient ultracentrifugation. The SPIs recovered in the low buoyant density fractions (rho < or = 1.35 g/ml) were purified by a combination of gel-permeation, ion-exchange, trypsin affinity, and reverse-phase high performance chromatographies. Characterisation of the major disc SPI by polyacrylamide gel electrophoresis, isoelectric focussing, enzyme inhibition and pH stability studies indicated that this small molecular weight (12-14 kDa), highly basic (pI > 9.5), acid-stable but alkaline-labile protein possessed potent inhibitory activity against bovine pancreatic trypsin and chymotrypsin, and human leukocyte elastase and cathepsin G. Two-major and two-minor low molecular weight cationic SPI species were identified by reverse-phase HPLC. The predominant species was identical to a human articular cartilage SPI sharing amino terminal sequence homology with the mucus proteinase inhibitors (MPIs). It also cross-reacted with an antiserum to the MPIs and behaved identically to secretory leucocyte proteinase inhibitor (SLPI) when examined by reverse phase HPLC, and SDS PAGE. A higher molecular weight (54 kDa), anionic (pI approximately 4.6) SPI was also purified and identified as alpha 1-proteinase inhibitor (alpha 1-PI). Quantification of alpha 1-PI and the small molecular weight cationic disc inhibitors indicated that the latter were depleted in morphologically degenerate disc tissues while levels of alpha 1-PI were somewhat higher although a large proportion of the alpha 1-PI was inactive. A depletion of total SPI levels was evident overall in degenerate discs suggesting a functional role for these inhibitory proteins in the maintenance of IVD matrix homeostasis.

A longitudinal study of the matrix changes induced in the intervertebral disc by surgical damage to the annulus fibrosus

A 5 x 5-mm anterolateral incision was made in the annulus fibrosus (AF) of lumbar discs of 16 sheep; four animals of similar age not operated on were used as controls. The experimental animals were sacrificed 2, 4, 6, 8, 12, and 18 months postoperatively (PO), and the incised and adjacent lumbar discs were collected. Discs were dissected into four zones: AF (zones 1 and 2) and nucleus pulposus (NP) (zones 3 and 4) corresponding to the half of the AF in which the cut was made and its opposite half, and the complementary halves of the NP. Each zone was analyzed for moisture, proteoglycan (PG), collagen, and noncollagenous protein (NCP) content. The PG extractability, aggregation, and hydrodynamic size were also examined. The NP of injured discs showed a significant loss of PGs and collagen 8 months PO, but NCP levels increased. In the incised discs, PG aggregation initially declined but recovered to within control values 6-8 months PO. The NP of discs adjacent to the incised disc also showed time-dependent changes in matrix components that included loss of collagen and PG; however, the AF matrix remained essentially uneffected. Double immunodiffusion studies indicated that a sizeable proportion of the NCPs present in the injured discs (but not the adjacent lumbar discs) were derived from serum.

A comparison of the high buoyant density proteoglycans isolated from the intervertebral discs of chondrodystrophoid and non-chondrodystrophoid dogs

Groups of purebred beagles and greyhounds of similar ages (1.5-2.5 years) were used for the study. Intervertebral disc proteoglycans (PGs) were radiolabelled in vivo (with [35SO4(2-)], 24 hours and 60 days prior to euthanasia, when lumbar discs were dissected into nucleus pulposus (NP) and annulus fibrosus (AF). Aliquots of each disc region were separately analysed for total PG content as hexuronate. The remaining tissue was subjected to extraction with 4.0 M GuHCl. High buoyant density PGs were isolated from these extracts by CsCl density gradient ultracentrifugation. The hydrodynamic size and aggregatability of the 24-hour, 60-day-old, and resident PG populations were determined by Sepharose CL2B chromatography in the presence or absence of excess hyaluronic acid. While the hydrodynamic sizes of the newly synthesized (24-hour) disc PG preparations appeared to be similar, the 60-day-old greyhound disc PGs were found to be larger than the corresponding beagle disc PG populations. However, the keratan sulphate-core protein complexes prepared by chondroitinase ABC digestion of the newly synthesized (24 hour) disc PGs showed that the greyhound disc preparations were also larger than those from beagle discs. Approximately 80% of the newly synthesized PGs from beagle and greyhound discs were capable of aggregating with hyaluronic acid, however, this was reduced to 55% for the 60 day-old PGs in NP and AF and even less for the resident PG populations (as determined by hexuronate analysis). Significantly, PG aggregation was lower in the greyhound NP and AF preparations than in the corresponding PGs isolated from the beagle disc.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity chromatography of serine proteinases from the bovine intervertebral disc on BPTI-Separon HEMA 1000

A method for the purification of serine proteinases from the bovine intervertebral disc using affinity chromatography on basic pancreatic trypsin inhibitor (BPTI) immobilized to the hydroxyalkyl methacrylate copolymer Separon HEMA 1000 E is reported. Its advantage is the possibility of obtaining serine proteinases without an artificial alteration in relative molecular mass.