Significant increases in serum and plasma concentrations of matrix metalloproteinases 3 and 9 in patients with rapidly destructive osteoarthritis of the hip

Mature and activated osteoclasts exist in the synovium of rapidly destructive coxarthrosis

We compared histological and functional findings in rapidly destructive coxarthrosis (RDC) and slowly progressive osteoarthritis (OA) to investigate whether osteoclasts contribute to the extensive bone destruction observed in RDC. A histological analysis of tissue specimens from the synovium obtained from 10 cases of RDC and 40 cases with OA of the hip was performed after staining for tartrate-resistant acid phosphatase (TRAP). The cells isolated from these tissue specimens from the synovium were cultured for 24 h, and the numbers of TRAP-positive giant cells were counted. Thereafter, we performed a resorption pit formation assay by isolated cells cultured on dentine slices for 7 days. The number of TRAP-positive multinuclear giant cells present in the synovial membrane obtained from RDC patients was significantly larger than that obtained from OA patients. Large lacunar resorption pits were only seen on the dentin slices in a culture of isolated cells from RDC patients without any stimulators. This is the first report, to our knowledge, to reveal that mature and activated osteoclasts exist only in the synovium of RDC and not in the OA synovium. This result might suggest that the underlying mechanism of RDC is therefore associated with osteoclastogenesis in the synovium.

Osteogenic protein 1 in synovial fluid from patients with rheumatoid arthritis or osteoarthritis: relationship with disease and levels of hyaluronan and antigenic keratan sulfate

The measurement of body fluid levels of biochemical markers in joint tissues has begun to provide clinically useful information. Synovial fluid (SF) plays an important role in articular joint lubrication, nutrition, and metabolism of cartilage and other connective tissues within the joint. The purpose of our study was to identify and characterize osteogenic protein 1 (OP-1) in SF from patients with rheumatoid arthritis (RA) or with osteoarthritis (OA) and to correlate levels of OP-1 with those of hyaluronan (HA) and antigenic keratan sulfate (AgKS). SF was aspirated from the knees of patients with either RA or OA and from the knees of asymptomatic organ donors with no documented history of joint disease. The presence of detectable OP-1 in SF was demonstrated by western blots with specific anti-pro-OP-1 and anti-mature OP-1 antibodies. Measurement of levels of OP-1, HA and AgKS was performed using ELISAs. OP-1 was identified in human SF in two forms, pro-OP-1 and active (mature) OP-1 – mature OP-1 being detected only in SF from OA patients and RA patients. Levels of OP-1 and HA were higher in RA patients than in OA patients and asymptomatic donors, while the level of AgKS was highest in SF from asymptomatic donors. Statistically significant differences were found between SF levels of OP-1 in RA and OA patients and between SF levels of AgKS among the three groups tested. The SF content of OP-1 tended to correlate positively with HA levels, but negatively with AgKS concentrations. In conclusion, the results of this study suggest that measurement of OP-1 in joint fluid may have value in the clinical evaluation of joint disease processes.

Rapid multifocal chondrolysis after liver transplantation in four patients

BACKGROUND

Favourable clinical outcomes achieved with liver transplantation may be jeopardised by corticosteroid-induced osteoarticular complications, such as osteoporosis or aseptic osteonecrosis.

CASE REPORT

A previously unreported joint complication in liver transplant recipients is described.

METHODS

Retrospective study of liver transplant recipients in whom destructive joint disease developed, identified among 330 symptomatic patients out of a total of 1260 managed over a 15 year period (November 1984-January 2000) in a university based liver transplantation centre.

RESULTS

In four patients (23-56 years), rapid chondrolysis developed 2-12 years after transplantation in more than three weightbearing or non-weightbearing joints free of radiological features of avascular osteonecrosis, evidence of infection, or defined inflammatory arthritis. Pathological examination of five hip joints and one knee joint found no evidence of infection or inflammation. Six joint replacement procedures were performed successfully in three patients.

CONCLUSION

Clinicians managing liver transplant recipients, and perhaps recipients of other organs, should be aware that rapid chondrolysis may develop. The pathogenesis of this rare complication is unclear.

Transcriptional induction of matrix metalloproteinase-9 in the chondrocyte and synoviocyte cells is regulated via a novel mechanism: evidence for functional cooperation between serum amyloid A-activating factor-1 and AP-1

Increased expression of matrix metalloproteinase-9 (MMP-9) by IL-1beta and TNF-alpha is regarded as a key factor in the degradation of cartilage during arthritis. However, the underlying molecular mechanism of this induction process especially in the cells of the joint capsule remains elusive. Chondrocytes and synoviocytes, the resident cells of joint capsule, markedly increase transcription of MMP-9 in response to IL-1beta- and TNF-alpha-mediated stimulation. Using progressively deleted and mutant promoter constructs of MMP-9, we show that serum amyloid A-activating factor (SAF)-1, a novel transcription factor, and the AP-1 family of proteins cooperatively regulate cytokine-mediated induction of MMP-9 in the resident cells of the joint capsule. In the MMP-9 promoter, SAF-1 and AP-1 DNA-binding elements are present in close proximity with only 14 nucleotides apart. SAF-1 DNA-binding activity is increased in both cytokine-stimulated cells as well as in osteoarthritic cartilage tissues. Although overexpression of SAF-1 could increase expression of the MMP-9 promoter and endogenous MMP-9 gelatinolytic activity, for maximal induction of MMP-9 gene concurrent participation of SAF-1 and AP-1 is required. Mutation of either one of these two elements resulted in a severe reduction in cytokine responsiveness of MMP-9 promoter and compromised the transactivation potential of both SAF-1 and AP-1. Simultaneous requirement for two distinct DNA-binding elements suggests that SAF-1 and AP-1 function in a mutually beneficial manner acting as essential coactivators to drive cytokine-mediated transcriptional activation of MMP-9.

Serum matrix metalloproteinase-3 concentration is influenced by MMP-3 -1612 5A/6A promoter genotype and associated with myocardial infarction

OBJECTIVES

Matrix metalloproteinase-3 (MMP-3) is implicated in the formation of atherosclerotic plaques, and the MMP-3 -1612 5A/6A polymorphism is associated with myocardial infarction (MI) and stable coronary artery disease (CAD). The present study examined whether the -1612 5A/6A polymorphism in the promoter region of the MMP-3 gene influences serum concentrations of MMP-3 and whether serum concentrations of MMP-3 are related to extent of coronary atherosclerosis and risk of MI.

DESIGN AND SUBJECTS

This case-control study was conducted in three hospitals in the northern part of Stockholm. A total of 755 MI patients aged below 60 were screened, 433 entered and 387 completed the study. Three hundred and eighty-seven sex- and age-matched control subjects were recruited from the general population of the same county.

METHODS

The MMP-3 genotype was determined by Pyrosequencing(TM) and the serum MMP-3 concentration was quantified with an immunoassay. Severity and extension of CAD was assessed by quantitative coronary angiography in a subgroup of patients (n=243).

RESULTS

Patients had lower serum MMP-3 concentration than controls. There was a strong association between MMP-3 -1612 5A/6A genotype and serum concentrations of MMP-3. The presence of one or two copies of the 6A-allele was associated with a graded increase in serum MMP-3. In female patients there was an inverse correlation (r=-0.39, P<0.05) between serum MMP-3 concentration and plaque area. Conclusion. In conclusion, the serum concentration of MMP-3 is influenced by MMP-3 -1612 5A/6A genotype and associated with MI.

Synovial proinflammatory cytokines and their correlation with matrix metalloproteinase-3 expression in Behçet's disease. Does interleukin-1beta play a major role in Behçet's synovitis?

The objective of this study has been the well established fact that proinflammatory cytokines and metalloproteinases play a crucial role in the pathogenesis of chronic arthritis as well as the development of pannus, with the eventual erosive changes. Among the proinflammatory cytokines, interleukin-18 (IL-18) has been shown to contribute to the pathogenesis of chronic synovitis by increasing the secretion of interleukin-1beta (IL-1beta) and the tumor necrosis factor-alpha (TNF-alpha) and also stimulating angiogenesis. The aim of this study is to investigate the synovial IL-18, IL-1beta, TNF-alpha and matrix metalloproteinase-3 (MMP-3) levels in patients with Behçet's disease (BD), and compare them with the levels of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). 30 patients with BD, 20 with RA, and 20 with OA were included in the study. The synovial levels of IL-18, IL-1beta, TNF-alpha and MMP-3 were detected using the two-step sandwich ELISA method. The synovial IL-18, TNF-alpha and MMP-3 levels were significantly higher in RA patients than patients with BD (P=0.004, 0.019, 0.025, respectively) and with OA (P=0.004, 0.045, 0.032, respectively). There were no differences, with respect to the cytokine levels, when patients with BD were compared with those with OA. Patients with RA and BD had higher IL-1beta levels than patients with OA (P=0.017, 0.013, respectively). However, no such difference was found for IL-1beta between BD and RA patients. Among patients with RA, positive correlations were found between TNF-alpha and MMP-3 (r=0.683, P=0.001). Our results showed that MMP-3 and proinflammatory cytokines, except IL-1beta, were expressed in relatively small quantities in Behçet's synovitis. Detection of the lower levels of these cytokines and metalloproteinases might explain the non-erosive character of Behçet's arthritis. We suggest that IL-1beta may be involved in the pathogenesis of Behçet's synovitis.

Rapidly destructive coxopathy after subchondral insufficiency fracture of the femoral head

Rapidly destructive coxopathy (RDC) is a rare disorder, and its pathophysiology is unknown. Here, we report a case of RDC evaluated by roentgenography and magnetic resonance imaging, from the onset of hip pain without changes on roentgenograms, to the terminal stage with collapse of the femoral head. Our serial radiological findings clearly illustrate the entire process of RDC, especially the initial stage. Subchondral insufficiency fracture of the femoral head seems to be an important preliminary event in the development of RDC.

Joint and bone disease in mucopolysaccharidoses VI and VII: identification of new therapeutic targets and biomarkers using animal models

The mucopolysaccharidoses (MPS) are inherited metabolic disorders resulting from the defective catabolism of glycosaminoglycans. In this report, we find that the stimulation of MPS connective tissue cells by the inflammatory cytokines causes enhanced secretion of several matrix-degrading metalloproteinases (MMPs). In addition, expression of tissue inhibitor of metalloproteinase-1 was elevated, consistent with the enhanced MMP activity. These findings were not restricted to one particular MPS disorder or species, and are consistent with previous observations in animal models with chemically induced arthritis. Bromodeoxyuridine incorporation studies also revealed that MPS chondrocytes proliferated up to 5-fold faster than normal chondrocytes, and released elevated levels of transforming growth factor-beta, presumably to counteract the marked chondrocyte apoptosis and matrix degradation associated with MMP expression. Despite this compensatory mechanism, studies of endochondral ossification revealed a reduction in chondro-differentiation in the growth plates. Thus, although MPS chondrocytes grew faster, most of the newly formed cells were immature and could not mineralize into bone. Our studies suggest that altered MMP expression, most likely stimulated by inflammatory cytokines and nitric oxide, is an important feature of the MPS disorders. These data also identify several proinflammatory cytokines, nitric oxide, and MMPs as novel therapeutic targets and/or biomarkers of MPS joint and bone disease. This information should aid in the evaluation of existing therapies for these disorders, such as enzyme replacement therapy and bone marrow transplantation, and may lead to the development of new therapeutic approaches.

Novel inhibitors of matrix metalloproteinase gene expression as potential therapies for arthritis

Matrix metalloproteinases are a family of endopeptidases that collectively degrade all components of the extracellular matrix at neutral pH. During the progression of arthritis, MMPs mediate the degradation of cartilage, which consists largely of Type II collagen fibrils and proteoglycans. The collagenases, a subgroup of MMPs, have the singular ability to cleave intact collagens and may provide a rate-limiting step in cartilage destruction. In arthritic lesions, collagenase-1 (matrix metalloproteinase-1) and collagenase-3 (matrix metalloproteinase-13) mediate the irreversible destruction of cartilage, suggesting that these enzymes are therapeutic targets. We describe the role of metalloproteinases in the destruction of connective tissues in arthritis and the treatment strategies that have been developed to block matrix metalloproteinases in an attempt to prevent this destruction. We also discuss novel compounds that may selectively inhibit these cartilage-degrading enzymes, providing opportunities to develop new therapeutic approaches.

Pro-MMP-9 is a specific macrophage product and is activated by osteoarthritic chondrocytes via MMP-3 or a MT1-MMP/MMP-13 cascade

In joint diseases of both the inflammatory (rheumatoid arthritis, or RA) or the degenerative variety (osteoarthritis, or OA), matrix metalloproteinases (MMPs) are essential mediators of irreversible tissue destruction. MMP-9 is secreted as a stable, inactive zymogen and is proteolytically converted to the active enzyme. To understand the activation mechanism of MMP-9 in joint diseases, the process was investigated in serum-free cocultures of human articular chondrocytes and macrophages. Macrophages extensively expressed and secreted pro-MMP-9 whereas chondrocytes failed to produce the enzyme. However, efficient activation of pro-MMP-9 required soluble and membrane-associated chondrocyte proteinases. Two alternative activation pathways mainly involved MMPs and, marginally, serine or cysteine proteinases. MT1-MMP (MMP-14), the only MT-MMP expressed in chondrocytes, converted pro-MMP-13 which, in turn, cleaved pro-MMP-9. Alternatively, pro-MMP-9 was activated less efficiently by MMP-3, which was converted by autocatalysis or by serine or cysteine proteinases. Both pathways were triggered by chondrocytes from OA, but not normal joints. Therefore, articular chondrocytes are not innocent bystanders in joint diseases. They not only produce destructive enzymes guided by environmental cues but also they can instruct inflammatory cells or cells from surrounding tissues to do so by converting in several ways zymogens produced but not activated by these cells themselves.

Measurement of structural progression in osteoarthritis of the hip: the Barcelona consensus group

OBJECTIVE

To outline the best available method of measurement for detecting progression of osteoarthritis (OA) of the hip especially in therapeutic trials.

METHOD

A Medline search of articles related to progression of hip OA was performed. A group of experts met over a 1.5-day session to review available literature and new research. Specific questions were addressed in order to reach a consensus on measuring progression of OA of the hip.

RESULTS

Of the available surrogate measures, a single yearly standing or reclined antero-posterior plain radiograph of the pelvis with feet internally rotated 15-20 degrees, can be evaluated with the use of an atlas for joint space width (JSW, interbone distance). There should be a minimum JSW upon baseline screening that may be 1 or 2 mm. Digitization of films offers a slight reduction in variability of measurements. Progression of OA can be calculated by measurement of the JSW on paired and blinded films. A reduction of > or = 0.5 mm is greater than the 'minimum perceptible difference' as well as the variation of most imaging techniques, and represents a clinically relevant and significant reduction in the JSW. Narrowing of the superomedial or superolateral JSW may tend to progress more rapidly than other changes. In clinical trials, patients who discontinue the study treatment need to be followed after discontinuation, and an imputation strategy which provides unbiased estimates of both the treatment effect and its variance is an appropriate technique for intent-to-treat analysis.

CONCLUSION

For the development of new agents intended to prevent, retard, stabilize or reverse the progress of OA of the hip, the radiographic methodology presently available is adequate to detect changes in hip JSW of OA.

Biomarkers in osteoarthritis

PURPOSE OF REVIEW

Osteoarthritis is a chronic disease characterized by progressive destruction of articular cartilage and subchondral bone, and synovial reaction. Clinical and radiologic findings that form the basis of the diagnosis of osteoarthritis are poorly sensitive for monitoring the progression of the disease. Biologic markers reflecting quantitative and dynamic changes of joint tissue turnover represent promising adjunct tools.

RECENT FINDINGS

New tissue-specific markers have been developed and include assays for type II collagen synthesis and degradation and synovitis. Prospective studies indicate that increased or decreased levels of some of these markers are associated with rapid progression of joint destruction in patients with knee osteoarthritis. Because progression of joint damage is likely to result primarily from an imbalance between degradation and reparative processes, a combination of markers reflecting these two components appears promising. For example, combining two new markers for type II collagen synthesis and degradation in an uncoupling index of cartilage turnover was more effective in predicting 1-year radiologic progression in knee osteoarthritis than the measurement of a single marker. Preliminary data in rheumatoid arthritis show a rapid response of a marker of type II collagen degradation under disease-modifying antirheumatic drugs, with early changes of this marker being predictive of long-term radiologic progression.

SUMMARY

Recent evidence suggests that the combination of some biologic markers will be useful for identifying patients at risk for rapid joint destruction in osteoarthritis. Because of their rapid changes under treatment, biologic markers will play an important role in the development and monitoring of new structure-modifying therapies for osteoarthritis.

Is pro-matrix metalloproteinase-3 a marker for posttraumatic cartilage degradation?

OBJECTIVE

Since the development of posttraumatic osteoarthritis (OA) is a relatively slow process, estimation of OA risk would be of value with regard to chondroprotective measures and medication. In this study we investigated the significance of pro-matrixmetalloproteinase-3 (proMMP-3) for this purpose.

DESIGN

Synovial fluid (SF) and serum samples were collected from 259 patients of our trauma clinic at the time of arthroscopy. The extent of cartilage damage was assessed according to the Outerbridge-score. ProMMP-3 levels in SF and serum were determined by enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody. Additionally we determined SF and serum levels of total MMP-3 and COMP levels as well as TIMP-1 and -2 concentrations in 40 randomly selected patients by ELISA.

RESULTS

Serum proMMP-3 levels of the total cohort were markedly increased compared to healthy controls (P<0.007). The comparison of serum and SF lavage proMMP-3 concentrations showed a significant correlation (r(s)=0.41, P<0.0001), however, only 26% of the investigated samples were increased above normal ranges. The grade of cartilage damage did not correlate with enzyme concentration neither in patients' serum nor in SF samples. ProMMP-3 SF concentration was increased early after trauma. Furthermore, proMMP-3 correlated significantly with total MMP-3 serum and SF levels as well as COMP SF levels.

CONCLUSIONS

The measurement of proMMP-3 in serum or SF did not reflect the present cartilage damage and thus appears to have only minor potential for clinical use, but it should be considered for longitudinal studies, since it may reflect a risk for cartilage degradation in a subset of patients.