Bovine primary chondrocyte culture in synthetic matrix metalloproteinase-sensitive poly(ethylene glycol)-based hydrogels as a scaffold for cartilage repair

A poly(ethylene glycol) (PEG)-based hydrogel was used as a scaffold for chondrocyte culture. Branched PEG-vinylsulfone macromers were end-linked with thiol-bearing matrix metalloproteinase (MMP)-sensitive peptides (GCRDGPQGIWGQDRCG) to form a three-dimensional network in situ under physiologic conditions. Both four- and eight-armed PEG macromer building blocks were examined. Increasing the number of PEG arms increased the elastic modulus of the hydrogels from 4.5 to 13.5 kPa. PEG-dithiol was used to prepare hydrogels that were not sensitive to degradation by cell-derived MMPs. Primary bovine calf chondrocytes were cultured in both MMP-sensitive and MMP-insensitive hydrogels, formed from either four- or eight-armed PEG. Most (>90%) of the cells inside the gels were viable after 1 month of culture and formed cell clusters. Gel matrices with lower elastic modulus and sensitivity to MMP-based matrix remodeling demonstrated larger clusters and more diffuse, less cell surface-constrained cell-derived matrix in the chondron, as determined by light and electron microscopy. Gene expression experiments by real-time RT-PCR showed that the expression of type II collagen and aggrecan was increased in the MMP-sensitive hydrogels, whereas the expression level of MMP-13 was increased in the MMP-insensitive hydrogels. These results indicate that cellular activity can be modulated by the composition of the hydrogel. This study represents one of the first examples of chondrocyte culture in a bioactive synthetic material that can be remodeled by cellular protease activity.

Tenascin-C and matrix metalloproteinase-9 levels in crevicular fluid of teeth and implants

The role of and interaction between bacterial infection and biomechanical impact in the development of peri-implant inflammatory processes is not clear.

Gelatinase B [matrix metalloproteinase (MMP)-9] and collagenases (MMP-8/-13) are upregulated in cerebrospinal fluid during aseptic and bacterial meningitis in children

We investigated the protein expression of gelatinases [matrix metalloproteinase (MMP)-2 and -9] and collagenases (MMP-8 and -13) in cerebrospinal fluid (CSF) from patients with bacterial (BM, n = 17) and aseptic (AM, n = 14) meningitis. In both, MMP-8 and -9 were increased in 100% of patients, whereas MMP-13 was detectable in 53% and 82% respectively. Three patients with clinical signs of meningitis, without CSF pleocytosis, scored positive for all three MMPs. MMP-8 appeared in two isoforms, granulocyte-type [polymorphonuclear cell (PMN)] and fibroblast/macrophage (F/M) MMP-8. Analysis of kinetic changes from serial lumbar punctures showed that these MMPs are independently regulated, and correlate only partly with CSF cytosis or levels of the endogenous inhibitor, tissue inhibitor of matrix metalloproteinase-1. In vitro, T cells, peripheral blood mononuclear cells (PBMCs) and granulocytes (PMN) release MMP-8 and -9, whereas MMP-13 could be found only in the former two cell types. Using models of exogenous (n-formyl-Met-Leu-Phe, T cell receptor cross-linking) and host-derived stimuli (interleukin-2), the kinetics and the release of the MMP-8, -9 and -13 showed strong variation between these immune cells and suggest release from preformed stocks. In addition, MMP-9 is also synthesized de novo in PBMCs and T cells. In conclusion, invading immune cells contribute only partially to MMPs in CSF during meningitis, and parenchymal cells are an equally relevant source. In this context, in patients with clinical signs of meningitis, but without CSF pleocytosis, MMPs seem to be a highly sensitive marker for intrathecal inflammation. The present data support the concept that broad-spectrum enzyme inhibition targeting gelatinases and collagenases is a potential strategy for adjunctive therapy in infectious meningitis.

Matrix metalloproteinase-19 is a predictive marker for tumor invasiveness in patients with oropharyngeal squamous cell carcinoma

AIMS: To evaluate the expression of matrix metalloproteinase-19 (MMP-19) in oropharyngeal squamous cell carcinoma along with its association with structural features of invasiveness. To investigate whether MMP-19 expression correlates with lymphatic or systemic metastasis and prognosis in patients who have received definitive radiotherapy. METHODS AND RESULTS: The histological evaluation of the invasive front was based on Bryne's malignancy grading system. We correlated the immunohistochemical expression pattern with morphological parameters which characterize tumor invasiveness such as keratinization, nuclear polymorphism, invasion pattern, and the host inflammatory response. Local immunoreactivity for MMP-19 was positively correlated with tumor invasiveness as reflected in its structural characteristics and the degree of nuclear polymorphism, and negatively correlated with the inflammatory response of the host. No correlation existed between MMP-19 expression and clinicopathological features (TNM stage, grade of differentiation) or a patient''s outcome and prognosis. CONCLUSIONS: This latter finding probably reflects the unique change for MMPs from high immunoreactivity within healthy tissue areas and non-invasive tumor parts, through absence in the least invasive neoplastic regions, to strong re-expression at a highly invasive front of the same tumor. Our findings indicate that MMP-19 can be used as a marker for tumor invasiveness in patients with oropharyngeal squamous cell carcinoma.

Matrix metalloproteinase-9 in pneumococcal meningitis: activation via an oxidative pathway

In experimental bacterial meningitis, matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) contribute to brain damage. MMP-9 increases in cerebrospinal fluid (CSF) during bacterial meningitis and is associated with the brain damage that is a consequence of the disease. This study assesses the origin of MMP-9 in bacterial meningitis and how ROS modulate its activity. Rat brain-slice cultures and rat polymorphonuclear cells (PMNs) that had been challenged with capsule-deficient heat-inactivated Streptococcus pneumoniae R6 (hiR6) released MMP-9. Coincubation with either catalase, with the myeloperoxidase inhibitor azide, or with the hypochlorous acid scavenger methionine almost completely prevented activation, but not the release, of MMP-9, in supernatants of human PMNs stimulated with hiR6. Thus, in bacterial meningitis, both brain-resident cells and invading PMNs may act as sources of MMP-9, and stimulated PMNs may activate MMP-9 via an ROS-dependent pathway. MMP-9 activation by ROS may represent a target for therapeutic intervention in bacterial meningitis.

Matrix metalloproteinase inhibition lowers mortality and brain injury in experimental pneumococcal meningitis

Pneumococcal meningitis (PM) results in high mortality rates and long-lasting neurological deficits. Hippocampal apoptosis and cortical necrosis are histopathological correlates of neurofunctional sequelae in rodent models and are frequently observed in autopsy studies of patients who die of PM. In experimental PM, inhibition of matrix metalloproteinases (MMPs) and/or tumor necrosis factor (TNF)-converting enzyme (TACE) has been shown to reduce brain injury and the associated impairment of neurocognitive function. However, none of the compounds evaluated in these studies entered clinical development. Here, we evaluated two second-generation MMP and TACE inhibitors with higher selectivity and improved oral availability. Ro 32-3555 (Trocade, cipemastat) preferentially inhibits collagenases (MMP-1, -8, and -13) and gelatinase B (MMP-9), while Ro 32-7315 is an efficient inhibitor of TACE. PM was induced in infant rats by the intracisternal injection of live Streptococcus pneumoniae. Ro 32-3555 and Ro 32-7315 were injected intraperitoneally, starting at 3 h postinfection. Antibiotic (ceftriaxone) therapy was initiated at 18 h postinfection, and clinical parameters (weight, clinical score, mortality rate) were recorded. Myeloperoxidase activities, concentrations of cytokines and chemokines, concentrations of MMP-2 and MMP-9, and collagen concentrations were measured in the cerebrospinal fluid. Animals were sacrificed at 42 h postinfection, and their brains were assessed by histomorphometry for hippocampal apoptosis and cortical necrosis. Both compounds, while exhibiting disparate MMP and TACE inhibitory profiles, decreased hippocampal apoptosis and cortical injury. Ro 32-3555 reduced mortality rates and cerebrospinal fluid TNF, interleukin-1β (IL-1β) and collagen levels, while Ro 32-7315 reduced weight loss and cerebrospinal fluid TNF and IL-6 levels.

Levels of matrix metalloproteinase-9 within cerebrospinal fluid in a rabbit model of coccidioidal meningitis and vasculitis.

Matrix metalloproteinase (MMP)-9 is produced by the central nervous system and inflammatory cells in a variety of inflammatory conditions in both animals and humans. MMP-9 promotes inflammation, breakdown of the blood-brain barrier, and vasculitis. Because vasculitis is seen frequently in patients with coccidioidal meningitis (CM), this study evaluated the presence of MMP-9 within the cerebrospinal fluid (CSF) of rabbits infected intracisternally with Coccidioides immitis arthroconidia. Infected rabbits demonstrated systemic and neurological sequelae to infection, including CSF pleocytosis. Levels of MMP-9 within CSF were assayed by use of zymography and compared with MMP-2 levels, which served as an internal control. Elevated levels of MMP-9 were detectable by day 3, continued to increase through day 10, and declined by day 15 after infection. MMP-9 may contribute to inflammation and vasculitis in this animal model. Future work can focus on evaluation of MMP inhibitors, to gain a better perspective of the role of this MMP in CM.

Matrix metalloproteinase (MMP)-8 and MMP-9 in cerebrospinal fluid during bacterial meningitis: association with blood-brain barrier damage and neurological sequelae.

To evaluate the spectrum and regulation of matrix metalloproteinases (MMPs) in bacterial meningitis (BM), concentrations of MMP-2, MMP-3, MMP-8, and MMP-9 and endogenous inhibitors of metalloproteinases (TIMP-1 and TIMP-2) were measured in the cerebrospinal fluid (CSF) of 27 children with BM. MMP-8 and MMP-9 were detected in 91% and 97%, respectively, of CSF specimens from patients but were not detected in control patients. CSF levels of MMP-9 were higher (P<.05) in 5 patients who developed hearing impairment or secondary epilepsy than in those who recovered without neurological deficits. Levels of MMP-9 correlated with concentrations of TIMP-1 (P<.001) and tumor necrosis factor-alpha (P=.03). Repeated lumbar punctures showed that levels of MMP-8 and MMP-9 were regulated independently and did not correlate with the CSF cell count. Therefore, MMPs may derive not only from granulocytes infiltrating the CSF space but also from parenchymal cells of the meninges and brain. High concentrations of MMP-9 are a risk factor for the development of postmeningitidal neurological sequelae.

Effects of stimulus with proinflammatory mediators on nitric oxide production and matrix metalloproteinase activity in explants of cranial cruciate ligaments obtained from dogs

OBJECTIVE To evaluate the origin and degree of activity of nitric oxide (NO) and matrix metalloproteinase (MMP) in explants of cranial cruciate ligaments (CCLs) obtained from dogs and cultured with and without inflammatory activators. SAMPLE POPULATION Tissue specimens obtained from 7 healthy adult Beagles that were (mean +/- SD) 4.5 +/- 0.5 years old and weighed 12.5 +/- 0.8 kg. PROCEDURE The CCLs were harvested immediately after dogs were euthanatized, and specimens were submitted for explant culture. Cultures were stimulated by incubation with a combination of interleukin-1, tumor necrosis factor-alpha, and lipopolysaccharide, or they were not stimulated. Culture supernatants were examined for production of NO nitrite-nitrate metabolites (NOts) and activity of MMP Cultured specimens were evaluated by use of immunohistochemical analysis to detect activity of inducible NO synthase (iNOS). RESULTS All ligament explants produced measurable amounts of NOts. Stimulated cultures produced significantly more NOts after incubation for 24 and 48 hours, compared with nonstimulated cultures. Production of MMP in supernatants after incubation for 48 hours was significantly higher in stimulated cultures than in nonstimulated cultures. Cells with positive staining for iNOS were detected on all slides. Positively stained cells were predominantly chondroid metaplastic. There was a significant difference in intensity of cell staining between stimulated and non-stimulated cultures. CONCLUSIONS AND CLINICAL RELEVANCE Explant cultures of intact CCLs obtained from dogs produce iNOS-induced NO. Stimulation of chondroid metaplastic cells in CCL of dogs by use of inflammatory activators can increase production of iNOS, NOts, and MMP.

Dominance of chemokine ligand 2 and matrix metalloproteinase-2 and -9 and suppression of pro-inflammatory cytokines in the epidural compartment after intervertebral disc extrusion in a canine model

BACKGROUND CONTEXT In canine intervertebral disc (IVD) disease, a useful animal model, only little is known about the inflammatory response in the epidural space. PURPOSE To determine messenger RNA (mRNA) expressions of selected cytokines, chemokines, and matrix metalloproteinases (MMPs) qualitatively and semiquantitatively over the course of the disease and to correlate results to neurologic status and outcome. STUDY DESIGN/SETTING Prospective study using extruded IVD material of dogs with thoracolumbar IVD extrusion. PATIENT SAMPLE Seventy affected and 13 control (24 samples) dogs. OUTCOME MEASURES Duration of neurologic signs, pretreatment, neurologic grade, severity of pain, and outcome were recorded. After diagnostic imaging, decompressive surgery was performed. METHODS Messenger RNA expressions of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF), interferon (IFN)γ, MMP-2, MMP-9, chemokine ligand (CCL)2, CCL3, and three housekeeping genes was determined in the collected epidural material by Panomics 2.0 QuantiGene Plex technology. Relative mRNA expression and fold changes were calculated. Relative mRNA expression was correlated statistically to clinical parameters. RESULTS Fold changes of TNF, IL-1β, IL-2, IL-4, IL-6, IL-10, IFNγ, and CCL3 were clearly downregulated in all stages of the disease. MMP-9 was downregulated in the acute stage and upregulated in the subacute and chronic phase. Interleukin-8 was upregulated in acute cases. MMP-2 showed mild and CCL2 strong upregulation over the whole course of the disease. In dogs with severe pain, CCL3 and IFNγ were significantly higher compared with dogs without pain (p=.017/.020). Dogs pretreated with nonsteroidal anti-inflammatory drugs revealed significantly lower mRNA expression of IL-8 (p=.017). CONCLUSIONS The high CCL2 levels and upregulated MMPs combined with downregulated T-cell cytokines and suppressed pro-inflammatory genes in extruded canine disc material indicate that the epidural reaction is dominated by infiltrating monocytes differentiating into macrophages with tissue remodeling functions. These results will help to understand the pathogenic processes representing the basis for novel therapeutic approaches. The canine IVD disease model will be rewarding in this process.

The matrix metalloproteinase inhibitor RS-130830 attenuates brain injury in experimental pneumococcal meningitis.

BACKGROUND Pneumococcal meningitis (PM) is characterized by high mortality and morbidity including long-term neurofunctional deficits. Neuropathological correlates of these sequelae are apoptosis in the hippocampal dentate gyrus and necrosis in the cortex. Matrix metalloproteinases (MMPs) play a critical role in the pathophysiology of PM. RS-130830 (Ro-1130830, CTS-1027) is a potent partially selective inhibitor of MMPs of a second generation and has been evaluated in clinical trials as an anti-arthritis drug. It inhibits MMPs involved in acute inflammation but has low activity against MMP-1 (interstitial collagenase), MMP-7 (matrilysin) and tumour necrosis factor α converting enzyme (TACE). METHODS A well-established infant rat model of PM was used where live Streptococcus pneumoniae were injected intracisternally and antibiotic treatment with ceftriaxone was initiated 18 h post infection (hpi). Treatment with RS-130830 (75 mg/kg bis in die (bid) i.p., n = 40) was started at 3 hpi while control littermates received the vehicle (succinylated gelatine, n = 42). RESULTS Cortical necrosis was significantly attenuated in animals treated with RS-130830, while the extent of hippocampal apoptosis was not influenced. At 18 hpi, concentrations of interleukin (IL)-1β and IL-10 were significantly lower in the cerebrospinal fluid of treated animals compared to controls. RS-130830 significantly reduced weight loss and leukocyte counts in the cerebrospinal fluid of survivors of PM. CONCLUSION This study identifies MMP inhibition, specifically with RS-130830, as an efficient strategy to attenuate disease severity and cortical brain injury in PM.

Circulating matrix metalloproteinase 9 levels in relation to sampling methods, femoral and carotid atherosclerosis.

OBJECTIVES To examine whether circulating levels of matrix metalloproteinase 9 (MMP-9) were associated with ultrasound-assessed intima-media thickness (IMT) and echolucent plaques in the carotid and femoral arteries. To examine preanalytical sources of variability in MMP-9 concentrations related to sampling procedures. SUBJECTS AND DESIGN Plasma and serum MMP-9 levels were compared with ultrasound assessed measures of femoral and carotid atherosclerosis, in a cross-sectional study of 61-year-old men (n = 473). Preanalytical sources of variability in MMP-9 levels were examined in 10 healthy subjects. Main outcome measures were circulating levels of MMP-9 in serum and plasma, IMT of the carotid and femoral arteries, and plaque status based on size and echolucency. SETTING Research unit at university hospital. RESULTS Plasma concentrations of total and active MMP-9 were associated with femoral artery IMT independently of traditional cardiovascular risk factors, and were higher in subjects with moderate to large femoral plaques. Plasma MMP-9 concentration was higher in men with echolucent femoral plaques (P = 0.006) compared with subjects without femoral plaques. No similar associations were found for carotid plaques. MMP-9 concentrations were higher in serum than in plasma, and higher when sampling was performed with Vacutainer than with syringe. MMP-9 levels in serum were more strongly associated with peripheral neutrophil count compared with MMP-9 levels in plasma. CONCLUSIONS Plasma MMP-9 levels were associated with atherosclerosis in the femoral artery, and total MMP-9 concentration was higher in men with echolucent femoral plaques. The choice of sample material and sampling method affect the measurements of circulating MMP-9 levels.

Activating enhancer binding protein 2 epsilon (AP-2ε)-deficient mice exhibit increased matrix metalloproteinase 13 expression and progressive osteoarthritis development.

INTRODUCTION The transcription factor activating enhancer binding protein 2 epsilon (AP-2ε) was recently shown to be expressed during chondrogenesis as well as in articular chondrocytes of humans and mice. Furthermore, expression of AP-2ε was found to be upregulated in affected cartilage of patients with osteoarthritis (OA). Despite these findings, adult mice deficient for AP-2ε (Tfap2e(-/-)) do not exhibit an obviously abnormal cartilaginous phenotype. We therefore analyzed embryogenesis of Tfap2e(-/-) mice to elucidate potential transient abnormalities that provide information on the influence of AP-2ε on skeletal development. In a second part, we aimed to define potential influences of AP-2ε on articular cartilage function and gene expression, as well as on OA progression, in adult mice. METHODS Murine embryonic development was accessed via in situ hybridization, measurement of skeletal parameters and micromass differentiation of mesenchymal cells. To reveal discrepancies in articular cartilage of adult wild-type (WT) and Tfap2e(-/-) mice, light and electron microscopy, in vitro culture of cartilage explants, and quantification of gene expression via real-time PCR were performed. OA was induced via surgical destabilization of the medial meniscus in both genotypes, and disease progression was monitored on histological and molecular levels. RESULTS Only minor differences between WT and embryos deficient for AP-2ε were observed, suggesting that redundancy mechanisms effectively compensate for the loss of AP-2ε during skeletal development. Surprisingly, though, we found matrix metalloproteinase 13 (Mmp13), a major mediator of cartilage destruction, to be significantly upregulated in articular cartilage of adult Tfap2e(-/-) mice. This finding was further confirmed by increased Mmp13 activity and extracellular matrix degradation in Tfap2e(-/-) cartilage explants. OA progression was significantly enhanced in the Tfap2e(-/-) mice, which provided evidence for in vivo relevance. This finding is most likely attributable to the increased basal Mmp13 expression level in Tfap2e(-/-) articular chondrocytes that results in a significantly higher total Mmp13 expression rate during OA as compared with the WT. CONCLUSIONS We reveal a novel role of AP-2ε in the regulation of gene expression in articular chondrocytes, as well as in OA development, through modulation of Mmp13 expression and activity.

Matrix metalloproteinases and angiogenic factors: predictors of survival after radical prostatectomy for clinically organ-confined prostate cancer?

The aim of the present study was to investigate whether biomarkers improve the prediction of recurrence-free, disease-specific, and overall survival in patients with clinically localized prostate cancer. A tissue microarray was constructed from prostate specimens of 278 patients who underwent open radical retropubic prostatectomy for clinically localized prostate cancer. For immunohistochemical studies, antibodies were used against matrix metalloproteinase (MMP)-2, MMP-3, MMP-7, MMP-9, MMP-13, and MMP-19, as well as against vascular endothelial growth factor, hypoxia-induced factor 1 , basic fibroblast growth factor, and cluster of differentiation 31. Univariate and multivariable analyses were performed to evaluate the potential predictors of overall, disease-specific, and recurrence-free survival. In univariate analysis of patients with clinically organ-confined prostate cancer, only higher expression levels of MMP-9 (hazard ratio [0.6], 95% CI 0.45-0.8) had a protective effect in terms of overall survival. This positive effect of high MMP-9 expression was also observed for recurrence-free (HR 0.88, 95% CI 0.78-0.99) and disease-specific survival (HR 0.5, 95% CI 0.36-0.73). In multivariable analysis, none of these potential markers was found to be an independent prognostic factor of survival. Of all MMPs and angiogenic factors tested, MMP-9 expression has the potential as a prognostic marker in patients undergoing radical prostatectomy for clinically organ-confined cases of prostate cancer.