Matrix metalloproteinases and aggrecanase: their role in disorders of the human intervertebral disc

STUDY DESIGN

A comprehensive immunohistochemical study of matrix metalloproteinase activity in discs from patients with different disc diseases.

OBJECTIVES

To identify individual matrix metalloproteinase enzymes that could contribute to the degeneration of the matrix of the intervertebral disc, to identify the cells that produce matrix metalloproteinases (for example, the endogenous disc cells or invading cells associated with vascularisation), and to determine if "aggrecanase" contributes to degradation of proteoglycans in disc disorders.

SUMMARY OF BACKGROUND DATA

Matrix disorganization and loss of substance are the most common findings in degenerate discs, and proteinase enzyme activity is one means of causing these changes.

METHODS

Forty-nine discs from 46 patients with degenerative disc disease, posterior anular tears, spondylolisthesis, or disc herniation were studied immunohistochemically to determine the presence of matrix metalloproteinases 1, 2, 3, 7, 8, 9 and 13, tissue metalloproteinases 1 and 2, and proteoglycan degradation products generated by either matrix metalloproteinases or aggrecanase activity. In addition, in situ zymography was used to confirm matrix metalloproteinase activity.

RESULTS

The most extensive staining was seen for matrix metalloproteinases 1, 2, 3, and 9, with 91%, 71%, 65%, and 72% of samples having some immunopositivity for the respective antibodies. In contrast, staining for matrix metalloproteinases 7 and 8 was much less (38% for both). Tissue inhibitor of metalloproteinases 1 and 2 were expressed in 34% and 79% of specimens, respectively. Matrix metalloproteinases were found particularly in cell clusters and blood vessels of degenerate discs, with staining correlating positively with macroscopic degenerative grade. For all of the enzymes, there was most staining in the herniation specimens and least in the autopsy samples. The opposite was true of staining for the matrix metalloproteinases inhibitor, tissue inhibitor of metalloproteinases 2, with most found in the autopsy specimens. Enzyme activity was confirmed by in situ zymography and staining for matrix metalloproteinase degradation products of proteoglycans. In addition, there was staining with antibodies demonstrating aggrecanase degradation products.

CONCLUSIONS

Matrix metalloproteinase activity is more prevalent in herniated discs than in other disc disorders studied, although matrix metalloproteinases may have been more common earlier in the disease progression. Matrix metalloproteinases can be produced by invading blood vessels and associated cells, as well as by indigenous disc cells. Aggrecanase activity, although present in some samples, was not as obvious as that of matrix metalloproteinases. In addition to altered matrix metalloproteinase production, there appears to be a change in the balance between enzymes and endogenous inhibitors, tissue inhibitors of metalloproteinases. This study highlights specific matrix metalloproteinases that might be most efficient to target in developing therapeutics for minimizing degradation of the extracellular matrix of the disc.

Chondroitinase ABC promotes sprouting of intact and injured spinal systems after spinal cord injury

Chondroitin sulfate proteoglycans (CSPGs) are inhibitory extracellular matrix molecules that are upregulated after CNS injury. Degradation of CSPGs using the enzyme chondroitinase ABC (ChABC) can promote functional recovery after spinal cord injury. However, the mechanisms underlying this recovery are not clear. Here we investigated the effects of ChABC treatment on promoting plasticity within the spinal cord. We found robust sprouting of both injured (corticospinal) and intact (serotonergic) descending projections as well as uninjured primary afferents after a cervical dorsal column injury and ChABC treatment. Sprouting fibers were observed in aberrant locations in degenerating white matter proximal to the injury in regions where CSPGs had been degraded. Corticospinal and serotonergic sprouting fibers were also observed in spinal gray matter at and below the level of the lesion, indicating increased innervation in the terminal regions of descending projections important for locomotion. Spinal-injured animals treated with a vehicle solution showed no significant sprouting. Interestingly, ChABC treatment in uninjured animals did not induce sprouting in any system. Thus, both denervation and CSPG degradation were required to promote sprouting within the spinal cord. We also examined potential detrimental effects of ChABC-induced plasticity. However, although primary afferent sprouting was observed after lumbar dorsal column lesions and ChABC treatment, there was no increased connectivity of nociceptive neurons or development of mechanical allodynia or thermal hyperalgesia. Thus, CSPG digestion promotes robust sprouting of spinal projections in degenerating and denervated areas of the spinal cord; compensatory sprouting of descending systems could be a key mechanism underlying functional recovery.

Focal degeneration of astrocytes in amyotrophic lateral sclerosis

Astrocytes emerge as key players in motor neuron degeneration in Amyotrophic Lateral Sclerosis (ALS). Whether astrocytes cause direct damage by releasing toxic factors or contribute indirectly through the loss of physiological functions is unclear. Here we identify in the hSOD1(G93A) transgenic mouse model of ALS a degenerative process of the astrocytes, restricted to those directly surrounding spinal motor neurons. This phenomenon manifests with an early onset and becomes significant concomitant with the loss of motor cells and the appearance of clinical symptoms. Contrary to wild-type astrocytes, mutant hSOD1-expressing astrocytes are highly vulnerable to glutamate and undergo cell death mediated by the metabotropic type-5 receptor (mGluR5). Blocking mGluR5 in vivo slows down astrocytic degeneration, delays the onset of the disease and slightly extends survival in hSOD1(G93A) transgenic mice. We propose that excitotoxicity in ALS affects both motor neurons and astrocytes, favouring their local interactive degeneration. This new mechanistic hypothesis has implications for therapeutic interventions.

Bone density, strength, and formation in adult cathepsin K (-/-) mice

Cathepsin K (CatK) is a cysteine protease expressed predominantly in osteoclasts, that plays a prominent role in degrading Type I collagen. Growing CatK null mice have osteopetrosis associated with a reduced ability to degrade bone matrix. Bone strength and histomorphometric endpoints in young adult CatK null mice aged more than 10 weeks have not been studied. The purpose of this paper is to describe bone mass, strength, resorption, and formation in young adult CatK null mice. In male and female wild-type (WT), heterozygous, and homozygous CatK null mice (total N=50) aged 19 weeks, in-life double fluorochrome labeling was performed. Right femurs and lumbar vertebral bodies 1-3 (LV) were evaluated by dual-energy X-ray absorptiometry (DXA) for bone mineral content (BMC) and bone mineral density (BMD). The trabecular region of the femur and the cortical region of the tibia were evaluated by histomorphometry. The left femur and sixth lumbar vertebral body were tested biomechanically. CatK (-/-) mice show higher BMD at the central and distal femur. Central femur ultimate load was positively influenced by genotype, and was positively correlated with both cortical area and BMC. Lumbar vertebral body ultimate load was also positively correlated to BMC. Genotype did not influence the relationship of ultimate load to BMC in either the central femur or vertebral body. CatK (-/-) mice had less lamellar cortical bone than WT mice. Higher bone volume, trabecular thickness, and trabecular number were observed at the distal femur in CatK (-/-) mice. Smaller marrow cavities were also present at the central femur of CatK (-/-) mice. CatK (-/-) mice exhibited greater trabecular mineralizing surface, associated with normal volume-based formation of trabecular bone. Adult CatK (-/-) mice have higher bone mass in both cortical and cancellous regions than WT mice. Though no direct measures of bone resorption rate were made, the higher cortical bone quantity is associated with a smaller marrow cavity and increased retention of non-lamellar bone, signs of decreased endocortical resorption. The relationship of bone strength to BMC does not differ with genotype, indicating the presence of bone tissue of normal quality in the absence of CatK.

The involvement of matrix metalloproteinases and inflammation in lumbar disc herniation

STUDY DESIGN

Surgically obtained herniated lumbar disc specimens were stained with hematoxylin-eosin or toluidine blue (for detection of proteoglycans) or were immunostained with monoclonal antibodies (CD68), antihuman interstitial collagenase (matrix metalloproteinase [MMP]-1) and antihuman stromelysin (MMP-3).

OBJECTIVE

To investigate the possible correlation of matrix metalloproteinase activity to granulation tissue formation and lumbar disc herniation, depending on the type of herniation.

SUMMARY OF BACKGROUND DATA

Interstitial collagenase and stromelysin have been implicated in the degradation of the matrix of articular cartilage in rheumatoid arthritis, osteoarthritis and degenerated disc tissues. However, their role in the herniation of the intervertebral disc has received little study.

METHODS

Twenty-one specimens of lumbar disc herniation (classified as protrusions, subligamentous extrusions, transligamentous extrusions, and sequestrations) and four nonherniated discs were stained with hematoxylin-eosin or toluidine blue or were immunostained with monoclonal antibodies to CD20, CD45RO, and CD68, anti-MMP-1, and anti-MMP-3, using the avidin-biotin-peroxidase complex method. The amount of granulation tissue and results of staining were graded to examine differences in histology among the four herniation types.

RESULTS

In sequestration and transligamentous extrusion specimens, granulation tissue containing many CD68-positive macrophages was commonly observed. Most cells in granulation tissue, as well as chondrocytes, stained positively with anti-MMP-1 and anti-MMP-3 antibodies. Granulation tissue was less commonly observed in subligamentous extrusions and was absent from most protrusion specimens and all nonherniated specimens. B and T lymphocytes could not be demonstrated in granulation tissue.

CONCLUSIONS

The increased staining of MMP-1 and MMP-3 associated with inflammatory cells of granulation tissue in herniated discs suggests a causal correlation of these proteinases to tissue degradation in herniation.

The steroidal aromatase inhibitor exemestane prevents bone loss in ovariectomized rats

The irreversible steroidal aromatase inhibitor exemestane (EXE) is one of three third generation aromatase inhibitors currently prescribed for advanced breast cancer in postmenopausal women. Its principal mechanism of action is to reduce estrogen by inhibiting its synthesis. In addition to its efficacy against breast cancer, its effects on other organs are important, especially when given to women with good-prognosis breast cancer or potentially to healthy women at increased risk of developing breast cancer. The purpose of this study was to evaluate the effects of EXE on bone and lipid metabolism in ovariectomized (OVX) rats. Ten-month-old Sprague-Dawley female rats were sorted into intact controls, intact + EXE, OVX controls, and OVX + EXE groups, and treated by weekly intramuscular injection with vehicle or 100 mg/kg EXE for 16 weeks. The bone mineral density (BMD), mechanical testing, histomorphometry, bone resorption marker-serum pyridinoline (PYD), and bone formation marker-serum osteocalcin (OC) were used to determine the effects of treatment on bone. In addition, total serum cholesterol, triglyceride, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were determined. BMD of the lumbar spine and femur were 11% and 7%, respectively, higher in OVX animals given EXE than in OVX controls (all Ps<0.001). Significant increases in the bending strength and toughness of the femora as well as the compressive strength and elastic modulus of the vertebrae were observed in OVX rats given EXE (all Ps<0.02 vs. OVX controls). Trabecular bone volume (BV) was significantly higher in OVX rats treated with EXE than in OVX controls (P<0.0001). In OVX animals, EXE reduced the OVX-induced increase of serum PYD by 96% (P<0.0001), and the OVX-induced increase of serum OC was completely prevented by treatment with EXE. In OVX animals, EXE resulted in a 28% reduction of serum cholesterol (P<0.0001) and reduced LDL by 64% compared with OVX controls (P<0.0001). The positive results of EXE on bone and lipid metabolism in the OVX rat model merit further investigation of the effects of EXE in postmenopausal women.

Effects of the steroidal aromatase inhibitor exemestane and the nonsteroidal aromatase inhibitor letrozole on bone and lipid metabolism in ovariectomized rats

PURPOSE

Exemestane (EXE) and letrozole (LET) are third-generation aromatase inhibitors currently prescribed for postmenopausal hormone-dependent breast cancer. The impact on end organs of estrogen depletion in menopausal women is of significant clinical importance. We studied the effects of EXE, its principal metabolite, 17-hydroexemestane (17-H-EXE), and LET on bone and lipid metabolism in ovariectomized (OVX) rats.

EXPERIMENTAL DESIGN

OVX rats were treated by weekly intramuscular injection for 16 weeks with 20, 50, and 100 mg/kg EXE, 20 mg/kg 17-H-EXE, and daily oral gavage of 1 mg/kg LET. At the end of the treatment period, bone mineral density (BMD), the bone resorption marker serum pyridinoline, the bone formation marker serum osteocalcin, bone mechanical properties, histomorphometry, and serum lipid concentrations were determined.

RESULTS

Lumbar vertebral and femoral BMD, bending strength of the femur, compressive strength of the fifth lumbar vertebra, and trabecular bone volume were significantly higher in OVX animals given EXE and 17-H-EXE than in OVX controls. EXE and 17-H-EXE significantly reduced an ovariectomy-induced increase in serum pyridinoline and serum osteocalcin. EXE and 17-H-EXE given to OVX rats caused significant reductions of serum cholesterol and low-density lipoprotein cholesterol. In contrast, OVX rats treated with LET had BMD, bone biomarkers, mechanical failure properties, and lipid levels similar to those of OVX controls.

CONCLUSIONS

EXE and 17-H-EXE significantly prevent bone loss, enhance bone mechanical strength, and lower serum cholesterol and low-density lipoprotein levels in OVX rats. These protective effects on end-organ function are not seen with the nonsteroidal inhibitor LET.

Neutral proteinases in human intervertebral disc. Role in degeneration and probable origin

Neutral proteinases were partially purified from human intervertebral disc by extraction with guanidine hydrochloride followed by Sephadex G-75 column chromatography. They showed gelatinolytic and elastolytic activities at neutral pH. The apparent molecular weights of these enzymes were 70 KD and 25 KD, the former being the complexed form of the latter. The sensitivity to various synthetic inhibitors indicated these enzymes to be serine elastases. Furthermore, they were considered to be leukocyte elastases because anti-leukocyte elastase antibody inhibited the proteinase activity of these enzymes. Proteinase activity was not detected in normal discs, except for some slight activity in the end-plate. In contrast, the degenerated discs showed high activity, especially in the nucleus pulposus and end-plate. Similar high levels of proteinase activity were found in the vertebral body adjacent to normal as well as degenerated discs. These findings suggest that leukocyte elastase, which is normally present in the vertebral body, flows into and degrades the matrix of the intervertebral disc under pathologic conditions.

Calcium and vitamin D enriched diets increase and preserve vertebral mineral content in aging laboratory rats

To assess the long-term effect of vitamin D or calcium supplementation on the skeletal metabolism of aging laboratory rodents, 1.5-month-old female Wistar rats were fed with diets containing twice the concentration of vitamin D (group 2) and of calcium (group 3) as in the usual rat chow. Follow-up to 24 months of age did not show significant differences between the enriched-diet groups and the controls (group 1) in terms of the vertebral body weight and protein content. Significantly higher bone mineral contents were found in groups 2 and 3 than were found in controls, as revealed by an increased bone mineral density (BMD: +62%, group 2; +48%, group 3) and vertebral calcium content (+73%, group 2; +84%, group 3). The vertebral alkaline phosphatase enzymatic activity was significantly lower in the enriched diet groups than in controls (-47%, group 2; -45%, group 3). The ratio alkaline phosphatase/acid phosphatase activity was markedly reduced in groups 2 and 3 (-57% and -59%, respectively), which might indicate a diminished rate of bone turnover. The trabecular bone volume (BV/TV) decreased in all groups during senescence, being significantly elevated in group 3 as compared to controls. Vitamin D and calcium dietary supplementations increase the axial mineral bone content in laboratory rats and might reduce the bone turnover. Their influence on the trabecular bone volume has yet to be examined.

Phospholipase A2 activity in herniated lumbar discs. Clinical correlations and inhibition by piroxicam

STUDY DESIGN

Prospective study of phospholipase A2 activity in the serum and intervertebral discs of patients undergoing surgery for sciatica due to disc herniation.

OBJECTIVES

To determine correlations between herniated disc phospholipase A2 and clinical, radiographic, and anatomic signs of common sciatica; to evaluate serum phospholipase A2 activity as a marker of disc phospholipase A2; and to investigate the in vivo effect of piroxicam on disc phospholipase A2.

SUMMARY OF BACKGROUND DATA

Several studies suggest disc inflammation as a mechanism of sciatica due to disc herniation, and phospholipase A2 emerges as a key enzyme of cartilage and disc tissues.

METHODS

Phospholipase A2 activity was determined, using the degradation of a specific substrate, in the serum and discs of 31 patients (14 treated with acetaminophen and 17 treated with piroxicam) undergoing surgery for sciatica due to lumbar disc herniation. Visual analog scale for pain, Dallas Pain Questionnaire, Lasègue's sign, radiographic stage of degeneration of the herniated disc, volume of disc herniation shown by computed tomography, and surgical findings were recorded.

RESULTS

Disc phospholipase A2 activity was independent of the patient's age or sex, the radiologic stage of disc degeneration, and the volume of the herniation, and showed no significant correlation with Lasègue's sign or pain measured on a visual analog scale. The correlation between disc phospholipase A2 and the Dallas category of items measuring the impact of pain on daily activities approached the level of significance (P = 0.07). Disc phospholipase A2 activity was significantly higher in cases of sequestrated discs than in other herniations. Disc phospholipase A2 was significantly correlated with serum phospholipase A2, and was significantly lower in patients treated with piroxicam than in those treated with acetaminophen.

CONCLUSIONS

Disc phospholipase A2 is thought to participate in the physiopathology of sciatica and to bemodulated by nonsteroidal anti-inflammatory drug therapy. Serum phospholipase A2 is suggested as a biologic marker of disc inflammation in patients with sciatica.

Collagen synthesis and types I, III, IV, and VI collagens in an animal model of disc degeneration

STUDY DESIGN

The present study sought to elucidate the changes that occur in collagen chemistry in the early phases of disc degeneration.

OBJECTIVE

To monitor the healing process of the injured anulus fibrosus and the secondary degenerative reactions in the nucleus pulposus.

SUMMARY OF BACKGROUND DATA

Despite the importance of collagen chemistry under pathologic conditions in the intervertebral disc, knowledge of this aspect is very limited.

METHODS

Fourteen pigs were stabbed with a scalpel blade in the anterior part of the anulus fibrosus of a lumbar disc. The animals were killed 2 weeks to 5 months after injury. The activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase, the total collagen content, and staining patterns for Types I, III, IV, and VI collagens were analyzed from different parts of the disc.

RESULTS

The most active phase of the healing process, assessed from the activities of enzymes involved in collagen biosynthesis, took place during the first month postoperatively. The anular lesion was found to cicatrize through formation of disorganized granulation tissue in which Type I, III, and, IV collagens were deposited. In the nucleus pulposus, activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase and total collagen content increased, and the originally rounded cells became more elongated, resembling fibroblasts.

CONCLUSIONS

The results of this study suggest that the altered composition of collagens observed in the degenerate porcine nucleus pulposus results from changes in cell phenotype: Notochondral cells were replaced by fibroblast-like cells. It is likely that trauma to the anulus fibrosus can initiate a progressive degenerative process in the disc tissue.

Clinical usefulness of the serum N-terminal propeptide of type I collagen as a marker of bone formation in hemodialysis patients

BACKGROUND

An intact collagen I amino-terminal propeptide (PINP) assay has been developed as a useful assay for bone formation. The present study was performed to investigate the clinical usefulness of serum PINP as a bone-formation marker in hemodialysis (HD) patients.

METHODS

PINP and other bone-formation markers, ie, bone alkaline phosphatase (BAP) and intact osteocalcin (OC), were determined in serum samples collected from 209 HD patients.

RESULTS

Serum PINP levels, in contrast to serum BAP and OC levels, did not change significantly during a single HD session (P = 0.069; n = 14). There were significant positive correlations between serum PINP and BAP (r = 0.723; P < 0.001) and OC values (r = 0.739; P < 0.001), as well as intact parathyroid hormone (r = 0.652; P < 0.001) and bone-resorption marker values: deoxypyridinoline (DPD; r = 0.823; P < 0.001), pyridinoline (PYD; r = 0.735; P < 0.001), and beta-crosslaps (r = 0.705; P < 0.001). Serum PINP values correlated significantly more strongly than serum BAP values with all bone-resorption markers. Serum PINP values significantly correlated negatively with annual changes in bone mineral density (BMD) in the distal third of the radius (r = -0.286; P < 0.001). When subjects were divided into tertiles according to degree of bone loss, subjects with greater bone loss had significantly greater serum PINP, BAP, and OC levels, although PINP and OC provided greater discrimination than BAP. PINP-PYD and PINP-DPD ratios, indices of osteoblast function not confounded by enhanced bone resorption, significantly positively correlated with annual BMD changes in the distal third of the radius (PINP-PYD ratio, P = 0.008; PINP-DPD, P = 0.015).

CONCLUSION

Serum PINP may provide a better marker of osteoblast function in HD patients and thus be clinically useful for predicting radius bone loss.

Overexpression of BDNF increases excitability of the lumbar spinal network and leads to robust early locomotor recovery in completely spinalized rats

Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical applications. This is a consequence of a number of impediments that axons encounter when trying to regrow beyond the lesion site, and that intraspinal rearrangements are subjected to. In the present study we evaluated (1) the possibility to improve locomotor recovery after complete transection of the spinal cord by means of an adeno-associated (AAV) viral vector expressing the neurotrophin brain-derived neurotrophic factor (BDNF) in lumbar spinal neurons caudal to the lesion site and (2) how the spinal cord transection and BDNF treatment affected neurotransmission in the segments caudal to the lesion site. BDNF overexpression resulted in clear increases in expression levels of molecules involved in glutamatergic (VGluT2) and GABAergic (GABA, GAD65, GAD67) neurotransmission in parallel with a reduction of the potassium-chloride co-transporter (KCC2) which contributes to an inhibitory neurotransmission. BDNF treated animals showed significant improvements in assisted locomotor performance, and performed locomotor movements with body weight support and plantar foot placement on a moving treadmill. These positive effects of BDNF local overexpression were detectable as early as two weeks after spinal cord transection and viral vector application and lasted for at least 7 weeks. Gradually increasing frequencies of clonic movements at the end of the experiment attenuated the quality of treadmill walking. These data indicate that BDNF has the potential to enhance the functionality of isolated lumbar circuits, but also that BDNF levels have to be tightly controlled to prevent hyperexcitability.

Association between the -1306C/T polymorphism of matrix metalloproteinase-2 gene and lumbar disc disease in Chinese young adults

Matrix metalloproteinase-2 (MMP-2) has been shown to play a pivotal role in the pathophysiology of lumbar disc disease (LDD). Increased expression and activity of MMP-2 has been documented in degenerative discs. The polymorphism -1306C/T in the promoter region of MMP-2 gene was reported to influence gene transcription and expression. The objective of this study was therefore to investigate the possible association of MMP-2 -1306C/T polymorphism with the occurrence and the clinical characteristics of LDD. MMP-2 genotypes were determined by polymerase chain reaction (PCR) and direct DNA sequencing in a case-control study involving 162 younger patients with LDD and 318 age- and sex-matched healthy adults. The results showed that the frequency of MMP-2 -1306CC genotype was significantly higher in LDD patients when compared with controls. Subjects with the CC genotype had nearly threefold increased risk for LDD (odds ratio 3.08; 95% confidence interval 1.84-5.16) compared with subjects carrying at least one variant T allele. Furthermore, this genotype was found to correlate with more severe grades of disc degeneration observed on magnetic resonance imaging scan. These findings suggest that MMP-2 -1306C/T polymorphism may be a genetic risk factor related to LDD susceptibility in the young adult population.

Inflammatory cytokine and catabolic enzyme expression in a goat model of intervertebral disc degeneration

Intervertebral disc degeneration is implicated as a leading cause of low back pain. Persistent, local inflammation within the disc nucleus pulposus (NP) and annulus fibrosus (AF) is an important mediator of disc degeneration and negatively impacts the performance of therapeutic stem cells. There is a lack of validated large animal models of disc degeneration that recapitulate clinically relevant local inflammation. We recently described a goat model of disc degeneration in which increasing doses of chondroitinase ABC (ChABC) were used to reproducibly induce a spectrum of degenerative changes. The objective of this study was to extend the clinical relevance of this model by establishing whether these degenerative changes are associated with the local expression of inflammatory cytokines and catabolic enzymes. Degeneration was induced in goat lumbar discs using ChABC at different doses. After 12 weeks, degeneration severity was determined histologically and using quantitative magnetic resonance imaging (MRI). Expression levels of inflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β], and IL-6) and catabolic enzymes (matrix metalloproteinases-1 [MMPs-1] and 13, and a disintegrin and metalloproteinase with thrombospondin type-1 motifs-4 [ADAMTS-4]) were assessed as the percentage of immunopositive cells in the NP and AF. With the exception of MMP-1, cytokine, and enzyme expression levels were significantly elevated in ChABC-treated discs in the NP and AF. Expression levels of TNF-α, IL1-β, and ADAMTS-4 were positively correlated with histological grade, while all cytokines and ADAMTS-4 were negatively correlated with MRI T2 and T1ρ scores. These results demonstrate that degenerate goat discs exhibit elevated expression of clinically relevant inflammatory mediators, and further validate this animal model as a platform for evaluating new therapeutic approaches for disc degeneration.

Expression of ADAMTS-4 (aggrecanase-1) and possible involvement in regression of lumbar disc herniation

STUDY DESIGN

Examination of ADAMTS-4 expression, and cellular lineages, distribution, and numbers of ADAMTS-4 (aggrecanase-1) expressing cells in herniated lumbar intervertebral discs.

OBJECTIVE

To determine the expression of ADAMTS-4, a metalloproteinase capable of digesting aggrecan, and its role in herniated lumbar intervertebral disc degradation.

SUMMARY OF BACKGROUND DATA

Matrix metalloproteinases degrade extracellular matrix of herniated discs, but the mechanism of aggrecan degradation, the major component of intervertebral discs, is poorly understood.

METHODS

Surgically resected herniated lumbar intervertebral discs from 22 patients were subclassified into protrusion, subligamentous extrusion, transligamentous extrusion, and sequestration types. Reverse transcriptase polymerase chain reaction, Western blot, and immunohistochemistry were used to evaluate ADAMTS-4 messenger ribonucleic acid and protein expression.

RESULTS

Expression of ADAMTS-4 messenger ribonucleic acid and protein was shown in the samples of herniated lumbar intervertebral discs. Immunohistochemical staining showed that ADAMTS-4 was mainly localized in CD68-positive mononuclear cells in granulation and adjacent disc tissues. ADAMTS-4 positive cell counts were significantly higher in transligamentous extrusion and sequestration than protrusion and subligamentous extrusion types. Alcian blue staining showed a decrease of proteoglycan in transligamentous extrusion and sequestration cases.

CONCLUSIONS

Macrophages infiltrating granulation and adjacent disc tissues express ADAMTS-4, suggesting its involvement in herniated disc regression.

Involvement of Spinal Angiotensin II System in Streptozotocin-Induced Diabetic Neuropathic Pain in Mice

Renin-angiotensin system (RAS) activity increases under hyperglycemic states, and is thought to be involved in diabetic complications. We previously demonstrated that angiotensin (Ang) II, a main bioactive component of the RAS, might act as a neurotransmitter and/or neuromodulator in the transmission of nociceptive information in the spinal cord. Here, we examined whether the spinal Ang II system is responsible for diabetic neuropathic pain induced by streptozotocin (STZ). Tactile allodynia was observed concurrently with an increase in blood glucose levels the day after mice received STZ (200 mg/kg, i.v.) injections. Tactile allodynia on day 14 was dose-dependently inhibited by intrathecal administration of losartan, an Ang II type 1 (AT1) receptor antagonist, but not by PD123319, an AT2 receptor antagonist. In the lumbar dorsal spinal cord, the expression of Ang II, Ang converting enzyme (ACE), and phospho-p38 mitogen-activated protein kinase (MAPK) were all significantly increased on day 14 after STZ injection compared with vehicle-treated controls, whereas no differences were observed among AT1 receptors or angiotensinogen levels. Moreover, the increase in phospho-p38 MAPK was significantly inhibited by intrathecal administration of losartan. These results indicate that the expression of spinal ACE increased in STZ-induced diabetic mice, which in turn led to an increase in Ang II levels and tactile allodynia. This increase in spinal Ang II was accompanied by the phosphorylation of p38 MAPK, which was shown to be mediated by AT1 receptors.

Ability of different techniques of measuring bone mass to determine vertebral bone loss in aging female rats

Changes in vertebral trabecular bone were quantified in female Wistar rats. This study utilized single photon absorptiometry for the measurement of bone mineral content (BMC), quantitative computed tomography (QCT) for the measurement of bone mineral density (BMD), and image analysis histomorphometry for the measurement of trabecular bone volume (TBV). The above measurements were accompanied by biochemical assays of protein and calcium concentrations in the tissues. Also, the activity of bone alkaline and acid phosphatases was measured. Lumbar vertebrae (L4, L5) in old rats 27 months old, compared with those of young rats 7 months old, showed significant decreases in BMC, BMD, TBV, protein and calcium, and enzyme activity. A high degree of correlation was recorded between the above changes. The various changes were accompanied by a marked reduction in the overall wet weight of the vertebrae. Hence, new noninvasive methods to quantitate bone mass can be applied in vivo to small laboratory animals such as the rat. These methods are much more accurate than standard radiographs in quantitating bone loss and are, therefore, recommended for experimental longitudinal studies related to aging of the skeleton.

Correlation between alkaline and acid phosphatase activities and age-related osteopenia in murine vertebrae

Lumbar vertebrae (L4) from CW-1 female mice were examined for age-related changes in alkaline and acid phosphatase activities from young to old age. Histochemically, both enzymes were encountered along the bony surfaces of both trabecular and cortical bones with no significant age-related changes in their distribution. Biochemical determinations of bone alkaline phosphatase (Alk'ase) activity revealed that for a given unit level of bone or the bone as a whole no significant changes took place, whereas acid phosphatase (Acid'ase) activity was found to have increased significantly with age. A high positive correlative relationship was noted between the calcium content and the trabecular bone volume of the same vertebrae. It may, therefore, be proposed that age-related bone loss in mice could be attributed to an enhanced resorption rather than to a substantial reduction in the formative potential of bone cells.

Progesterone- and dexamethasone-dependent osteoprogenitors in bone cell populations derived from rat vertebrae are different and distinct

Previous experiments have demonstrated that bone cell populations derived from explants of lumbar vertebral bone of adult female rats contain osteoprogenitors that require dexamethasone (Dex) or progesterone (Prog) to proliferate and differentiate into fully differentiated bone-forming osteoblasts. We now show that the Prog-dependent population cannot be detected in male rats after sexual maturation, but is present in prepubertal rats of both sexes and can be induced in adult male-derived populations by culturing the explants in medium containing 17beta-estradiol (10(-9)-10(-8) M). This suggested that the Prog- and Dex-dependent osteoprogenitors in adult female-derived populations were probably distinct populations and that the survival of the Prog-dependent osteoprogenitors and/or their ability to proliferate are dependent on the presence of estrogen. We then proceeded to prove this by using replica plating. When one of the paired colonies duplicated was cultured in medium containing Dex (10(-8) M) and the other in medium containing Prog (10(-5) M), 5.0% of duplicates formed bone in Prog only, 11.1% formed bone in Dex only, and 3.4% formed bone in both Prog and Dex. In all cases the size of the bone-forming colonies in Dex-treated cultures was larger than that in Prog-treated cultures, indicating that the effects of Dex on osteoprogenitor proliferation are greater than those of Prog. The results demonstrate the existence of three classes ofosteoprogenitors in adult female rat-derived bone cell populations: a class responding to Dex only, a class responding to Prog only, and a class responding to both Dex and Prog. The results also indicate that the effects of Prog are not mediated by Prog binding to the glucocorticoid receptor and imply that Prog plays an important role in maintaining bone mass through regulating the class of osteoprogenitors responsive to Prog.

Residual enzymatic activity as a prognostic factor in patients with Gaucher disease type 1: correlation with Zimran and GAUSS-I index and the severity of bone disease

BACKGROUND

Gaucher disease (GD) is an autosomal recessive disorder produced by mutations in the glucocerebrosidase gene (GBA), causing storage of glucosylceramide in reticuloendothelial cells in multiple organs. Traditionally, the prediction of the phenotype based on the genotype has been reported to be limited.

SUBJECTS AND METHODS

We investigated the correlation between the enzymatic residual activity (ERA) and the phenotype at diagnosis of the disease in 45 GD Spanish patients (44 with type I and 1 with type III GD). The genotype involved two of the following previously expressed proteins: c.517A > C (T134P), 1%; c.721G > A (G202R), 17%; c.1090G > T (G325W), 13.9%; c.1208G > A (S364N), 4.1%; c.1226A > G (N370S), 17.8%; c.1246G > A (G377S), 17.6%; c.1289C > T (P391L), 8.5%; c.1448T > C (L444P), 3%; and c.1504C > T (R463C), 24.5%. Recombinant alleles, deletion of 55 bp in exon 9 and 84GG mutation were considered as mutations with no residual enzymatic activity.

RESULTS

The ERA showed a statistically significant correlation with chitotriosidase (P < 0.001), age (P < 0.001), spleen size (P < 0.001), 'Zimran's Severity Score Index' (P < 0.01) and the 'Gaucher Disease Severity Score Index-Type I' (P <  0.0001) at diagnosis of the disorder. Previous to any medical intervention, a comparison between the ERA and bone involvement, demonstrated a statistically significant relationship (P < 0.01) between the two variables.

CONCLUSIONS

This study data allowed us to define a new criterion for prognostic assessment of the disease at diagnosis, called Protein Severity Index, which expresses the theoretical severity of the genotype presented by patients, according to the corresponding ERA.

Peripheral nerve lesion induces an up-regulation of Spy1 in rat spinal cord

Spy1, as a member of the Speedy/RINGO family and a novel activator of cyclin-dependent kinases, was shown to promote cell cycle progression and cell survival in response to DNA damage. While its expression and roles in nervous system lesion and repair were still unknown. Here, we performed an acute sciatic nerve injury model in adult rats and studied the dynamic changes of Spy1 expression in lumbar spinal cord. Temporally, Spy1 expression was increased shortly after sciatic nerve crush and peaked at day 2. Spatially, Spy1 was widely expressed in the lumbar spinal cord including neurons and glial cells. While after injury, Spy1 expression was increased predominantly in astrocytes and microglia, which were largely proliferated. Moreover, there was a concomitant up-regulation of CDK2 activity and down-regulation of p27. Collectively, we hypothesized peripheral nerve injury induced an up-regulation of Spy1 in lumbar spinal cord, which was associated with glial proliferation.

Phenytoin and sodium valproate but not levetiracetam induce bone alterations in female mice

Adverse effects on the bone are amongst the potentially adverse clinical consequences with antiepileptic drugs (AEDs). This study compared the effects of 3 AEDs (phenytoin (PHT), sodium valproate (SVP), and levetiracetam (LTM)) on the bones of a Swiss strain of albino female mice. Drugs were administered daily for 4 months at doses that produced plasma concentrations corresponding to the clinically relevant therapeutic ranges. PHT and SVP (but not LTM) significantly lowered the bone mineral density (BMD) of lumbar vertebrae (L2-L4) as evaluated by dual-energy X-ray absorptiometry (DEXA) scan. The findings were supported by histopathology of vertebral (lumbar) bone and analysis of bone turnover markers. While both PHT and SVP reduced alkaline phosphatase (ALP) and hydroxyproline (HxP) in lumbar vertebrae, and elevated tartarate-resistant acid phosphatase (TRAP) and urinary excretion of calcium, LTM did not affect any of these markers of bone turnover, indicating that the drug might be a safer option in female epileptic patients prone to bone changes.

Metastatic retroperitoneal paraganglioma in a 16-year-old girl. Case report, molecular pathological and cytogenetic findings

Retroperitoneal paraganglioma is a rare tumor, especially occurring in childhood and adolescence, with a marked tendency to become biologically malignant. It has not been possible to predict the clinical outcome of paraganglioma patients by conventional histology, hence malignancy can only be demonstrated by the occurrence of metastatic lesions. Currently, only limited information on the genetics of this tumor is available. We report on a 16-year-old girl with a large retroperitoneal paraganglioma and an osseous metastasis to the first lumbar vertebra. In addition to morphological and immunohistochemical examinations, a molecular cytogenetic analysis was performed. Comparative genomic hybridization (CGH) revealed imbalanced chromosomal aberrations with a loss of chromosome 1p and a gain of 1q, indicating isochromosome 1q. A loss of chromosome 3 as well as low-level gains of chromosomes 4, 5, 6q, 11q and 13q were detected. A PCR-based microsatellite analysis of 1p confirmed the loss of heterozygosity, including NB1 and NB2 putative tumor-suppressor gene regions. Telomerase activity, which is found in the majority of malignant tumors, could not be detected. The case presented here is the first more comprehensive molecular genetic analysis of a sporadic malignant paraganglioma.