Targeted search for scaling genes reveals matrixmetalloproteinase 3 as a scaler of the dorsal-ventral pattern in Xenopus laevis embryos.

How embryos scale patterning according to size is still not fully understood. Through in silico screening and analysis of reaction-diffusion systems that could be responsible for scaling, we predicted the existence of genes whose expression is sensitive to embryo size and which regulate the scaling of embryonic patterning. To find these scalers, we identified genes with strongly altered expression in half-size Xenopus laevis embryos compared with full-size siblings at the gastrula stage. Among found genes, we investigated the role of matrix metalloproteinase-3 (mmp3), which was most strongly downregulated in half-size embryos. We show that Mmp3 scales dorsal-ventral patterning by degrading the slowly diffusing embryonic inducers Noggin1 and Noggin2 but preventing cleavage of the more rapidly diffusing inducer Chordin via degradation of a Tolloid-type proteinase. In addition to unraveling the mechanism underlying the scaling of dorsal-ventral patterning, this work provides proof of principal for scalers identification in embryos of other species.

Clusterin secretion is attenuated by the proinflammatory cytokines interleukin-1ß and tumor necrosis factor-α in models of cartilage degradation.

The protein clusterin has been implicated in the molecular alterations that occur in articular cartilage during osteoarthritis (OA). Clusterin exists in two isoforms with opposing functions, and their roles in cartilage have not been explored. The secreted form of clusterin (sCLU) is a cytoprotective extracellular chaperone that prevents protein aggregation, enhances cell proliferation and promotes viability, whereas nuclear clusterin acts as a pro-death signal. Therefore, these two clusterin isoforms may be putative molecular markers of repair and catabolic responses in cartilage and the ratio between them may be important. In this study, we focused on sCLU and used established, pathophysiologically relevant, in vitro models to understand its role in cytokine-stimulated cartilage degradation. The secretome of equine cartilage explants, osteochondral biopsies and isolated unpassaged chondrocytes was analyzed by western blotting for released sCLU, cartilage oligomeric protein (COMP) and matrix metalloproteinases (MMP) 3 and 13, following treatment with the proinflammatory cytokines interleukin-1ß (IL-1ß) and tumor necrosis factor-α. Release of sulfated glycosaminoglycans (sGAG) was determined using the dimethylmethylene blue assay. Clusterin messenger RNA (mRNA) expression was quantified by quantitative real-time polymerase chain reaction. MMP-3, MMP-13, COMP, and sGAG release from explants and osteochondral biopsies was elevated with cytokine treatment, confirming cartilage degradation in these models. sCLU release was attenuated with cytokine treatment in all models, potentially limiting its cytoprotective function. Clusterin mRNA expression was down-regulated 7-days post cytokine stimulation. These observations implicate sCLU in catabolic responses of chondrocytes, but further studies are required to evaluate its role in OA and its potential as an investigative biomarker.

Matrix Metalloproteinase-3 induces proteoglycan degradation in gouty arthritis model.

BACKGROUND: Gout is an inflammatory arthritis resulting from precipitation of monosodium urate (MSU) crystals in joints and surrounding tissues. However, the mechanism underlying high levels of uric acid inducing gouty arthritis has not been clarified. OBJECTIVE: The purpose was to investigate the role of Matrix Metalloproteinase-3 (MMP-3) in the development of gouty arthritis from hyperuricemia. METHOD: MSU crystal-induced gouty arthritis model and chondrocytes were used to evaluate changes of MMP-3 levels. Western blot, qPCR and ELISA were performed to detect MMP-3, Tissue Inhibitors of Metalloproteinase-1 (TIMP-1) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs-4 (ADAMTS-4) expressions in rabbit chondrocytes. Expression of proteoglycan was determined through toluidine blue staining. Concentrations of glycosaminoglycan, Interleukin-6 (IL-6), Interleukin-1ß (IL-1ß) and Tumor Necrosis Factor-α (TNF-α) in chondrocytes were assessed via ELISA kits. Concentration of uric acid in supernate was tested by Automatic Analyzer. RESULTS: MMP-3 was significantly increased in rat serum, synovial fluid, cartilages and chondrocytes treated with high-level uric acid. Increased concentration of glycosaminoglycancould be observed in chondrocytes incubated with MMP-3, as well as the remarkable downregulation of proteoglycan expression. Furthermore, high-level uric acid contributed to the degradation of proteoglycan via the activation of MMP-3. IL-6, IL-1ß and TNF-α concentrations were increased significantly in 35 °C compared to 37 °C with MMP-3 and high-level uric acid. CONCLUSION: Our study showed that MMP-3 was enhanced by high levels of uric acid, which promoted proteoglycan degradation, and induced MSU crystallization in turn. A low temperature environment is an important factor in the development of gout.

Matrix metalloproteinase-3 in brain physiology and neurodegeneration.

Structural and functional synapse reorganization is one of the key issues of learning and memory mechanisms. Specific proteases, called matrix metalloproteinases (MMPs), play a pivotal role during learning-related modification of neural circuits. Different types of MMPs modify the extracellular perisynaptic environment, leading to the plastic changes in the synapses. In recent years, there has been an increasing interest in the role played by matrix metalloproteinase-3 (MMP-3) in various processes occurring in the mammalian brain, both in physiological and pathological conditions. In this review, we discuss a crucial function of MMP-3 in synaptic plasticity, learning, neuronal development, as well as in neuroregeneration. We discuss the involvement of MMP-3 in synaptic long-term potentiation, which is likely to have a profound impact on experience-dependent learning. On the other hand, we also provide examples of deleterious actions of uncontrolled MMP-3 activity on the central nervous system (CNS) and its contribution to Alzheimer's and Parkinson's diseases (AD and PD). Since the molecular mechanisms controlled by MMP-3 have a profound and diverse impact on physiological and pathological brain functioning, their deep understanding may be crucial for the development of more specific methods for the treatment of neuropsychiatric diseases.

CCAAT/Enhancer Binding Protein ß-Mediated MMP3 Upregulation Promotes Esophageal Squamous Cell Cancer Invasion In Vitro and Is Associated with Metastasis in Human Patients.

Aims: Metastasis is a significant obstacle to curing esophageal squamous cell carcinoma (ESCC). The CCAAT/enhancer binding protein ß (C/EBPß) and matrix metalloproteinase 3 (MMP3) are thought to play key roles in cancer invasion and metastasis. In this study, we aimed to detect whether C/EBPß-mediated tumor invasion was dependent on MMP3. In addition, we determined whether C/EBPß upregulation was associated with MMP3 levels and metastatic status in patients with ESCC. Materials and Methods: A total of 126 patients with ESCC were recruited for this study. The mRNA and protein levels of C/EBPß and MMP3 in ESCC cell lines and specimens from ESCC patient were determined by reverse transcription-polymerase chain reaction and western blot, respectively. Tumor cell invasion was analyzed using an in vitro Matrigel Invasion Assay. The correlation between C/EBPß and MMP3 expression was determined by Pearson's correlation analysis. Results: Both mRNA and protein levels of MMP3 were upregulated by C/EBPß overexpression and downregulated by C/EBPß siRNA in KYSE150 cell cultures. The promotion of ESCC cell invasion through C/EBPß was inhibited by MMP3 siRNA. The level of C/EBPß was correlated with MMP3 and metastatic status in patients with ESCC. Conclusions: C/EBPß upregulation promoted tumor cell invasion in an MMP3-dependent manner in vitro and was associated with metastatic status in ESCC.

Elevated matrix metalloproteinase-3 level may affect hearing function in patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune disease. Sensorineural and conductive hearing loss have been reported in RA, but the results of most studies are not in agreement. The pathogenesis of the hearing loss is not clearly understood. The presence of sensorineural hearing loss was related to matrix metalloproteinase-3 (MMP-3). The aim of this study was to assess hearing loss in RA patients and to examine the correlation between plasma MMP-3 levels and hearing loss in such patients. METHODS: This is a cross-sectional and analytic research. Subjects consisted of 21 RA patients with hearing loss as a study group and 21 RA patients without hearing loss as controls. All patients were evaluated by pure tone audiometry and tympanometry. The amounts of plasma MMP-3 were determined using enzyme-linked immunosorbent assay. Pearson Chi-square test was used to determine the correlation of gender, age, disease duration, erythrocyte sedimentation rate, and platelet count of both groups. Independent t-test was used to assess equality of mean values at 250 to 8000 Hz hearing thresholds, pure tone mean values, air-bone gaps, and MMP-3 plasma levels of both groups. RESULTS: This study found sensorineural (76.2%), conductive (14.3%), and mixed (9.5%) hearing loss. The most common degree of hearing loss was mild (66.7%). There was an increased incidence of As-type tympanogram in the study group (28.6%) and control group (47.6%). There were significant differences between both groups in mean hearing thresholds (p < 0.001), mean of air conduction thresholds at 1000 to 8000 Hz (p < 0.05), and mean of bone conduction thresholds in all frequencies (p < 0.05). The significant difference of mean MMP-3 levels was also found between the groups (p < 0.001). CONCLUSION: Hearing loss is a common finding in RA. MMP-3 plasma contributed to degrade the incudomalleolar and incudostapedial joints and could damage the inner ear hair cells due to oxidative process in RA.

Association of matrix metalloproteinase 3 and endogenous inhibitors with inflammatory markers in mitral valve disease and calcification.

Calcific mitral valve stenosis (MVS) is a common disease characterized by extensive remodeling of the extracellular matrix via matrix metalloproteinases (MMPs). The mechanism of calcification due to extensive matrix remodeling remains unclear. In this study, we investigated the relationship between MMP-3, tissue inhibitors of metalloproteinases (TIMPs) as well as pro-inflammatory cytokines and the phenomenon of calcification in MVS. 212 patients having rheumatic mitral stenosis (RMS) and 155 healthy control subjects were recruited in the Cardiology Department of La Rabta Hospital University. Levels of MMP-3, TIMPs, IL-6 and TNF-α were measured by ELISA sandwich assay, hs-CRP was measured by immunoturbidimetry. Plasma levels of MMP-3, TIMP-1 and MMP-3/TIMP-2 ratio were lower only in RMS women in comparison to the control group. Calcification degree correlated positively with MMP-3 in women and men. In addition, calcification was correlated positively with MMP-3/TIMPs ratio in women patients. The inflammatory parameters were positively associated with extracellular matrix turnover biomarkers in men patients. In patients, the level of MMP-3 was increased in men and women with a calcification score ≥ 5. In addition, MMP-3 level predicted the occurrence of calcification. At ROC curves analysis, the cut-off MMP-3 level was in women was 9.21 ng/ml (sensitivity 51.1%, specificity 89.3%) and in men was 12.84 ng/ml (sensitivity 78.6%, specificity 77.8%). The high levels of MMP-3 and the biomarkers of inflammation contribute to valvular remodeling and calcification of the mitral valve.

Involvement of microRNAs-MMPs-E-cadherin in the migration and invasion of gastric cancer cells infected with Helicobacter pylori.

It has been found that Helicobacter pylori （H. pylori）is not only the main cause of gastric cancer, but also closely related to its metastasis. E-cadherin cleavage induced by matrix metalloproteinases (MMPs) plays an important role in the tumor metastasis. In the present study, we investigated the role of microRNAs-MMPs-E-cadherin in migration and invasion of gastric cancer cells treated with H. pylori. The results showed that H. pylori induced migration and invasion of SGC-7901 cells with a down-regulation of E-cadherin expression, which were abolished by MMPs knock down, E-cadherin overexpression, mimics of miR128 and miR148a. MiR128/miR148a inhibitors restored MMP-3/MMP-7 expression, down-regulated E-cadherin level, and accelerated cellular migration and invasion. This study suggests that H. pylori induces migration and invasion of gastric cancer cells through reduction of E-cadherin function by activation of MMP-3, - 7. The present results also suggest that the activated MMPs/E-cadherin pathway is related with down-regulation of miR128/miR148a in the human gastric cancer cells infected with H. pylori.

Omentin-1 prevents cartilage matrix destruction by regulating matrix metalloproteinases.

Matrix metalloproteinases (MMPs) play a crucial role in the degradation of the extracellular matrix and pathological progression of osteoarthritis (OA). Omentin-1 is a newly identified anti-inflammatory adipokine. Little information regarding the protective effects of omentin-1 in OA has been reported before. In the current study, our results indicated that omentin-1 suppressed expression of MMP-1, MMP-3, and MMP-13 induced by the proinflammatory cytokine interleukin-1ß (IL-1ß) at both the mRNA and protein levels in human chondrocytes. Importantly, administration of omentin-1 abolished IL-1ß-induced degradation of type II collagen (Col II) and aggrecan, the two major extracellular matrix components in articular cartilage, in a dose-dependent manner. Mechanistically, omentin-1 ameliorated the expression of interferon regulatory factor 1 (IRF-1) by blocking the JAK-2/STAT3 pathway. Our results indicate that omentin-1 may have a potential chondroprotective therapeutic capacity.

Polyphosphate-induced matrix metalloproteinase-3-mediated proliferation in rat dental pulp fibroblast-like cells is mediated by a Wnt5 signaling cascade.

Although it is known that inorganic polyphosphate [Poly(P)] induces differentiation of osteoblasts, there are few reports concerning its effects on cell proliferation, especially in fibroblasts. Because we found that Poly(P) stimulates the proliferation of purified rat dental pulp fibroblast-like cells (DPFCs), matrix metalloproteinase (MMP)-3 small interfering RNA (siRNA) was transfected into purified rat DPFCs to investigate whether MMP-3 activity is induced by Poly(P) and/or is associated with cell proliferation in DPFCs. Real-time quantitative polymerase chain reaction, Western blots, an MMP-3 activity assay, and an enzyme-linked immunosorbent assay to assess cell proliferation were used in this study. Poly(P) induced expression of MMP-3 mRNA and protein, and increased MMP-3 activity and cell proliferation. Silencing of MMP-3 expression with siRNA yielded potent and significant suppression of Poly(P)-induced MMP-3 expression and activity, and decreased cell proliferation. Poly(P) also increased mRNA and protein levels of Wnt5 and the Wnt receptor Lrp5/Fzd9. Although exogenous MMP-3 could not induce Wnt5, exogenous Wnt5 was found to increase MMP-3 activity and, interestingly, the proliferation rate of DPFCs. Transfection with Wnt5a siRNA suppressed the Poly(P)-induced increase in MMP-3 expression and suppressed cell proliferation. These results demonstrate the sequential involvement of Wnt5 and MMP-3 in Poly(P)-induced proliferation of DPFCs, and may have relevance in our understanding and ability to improve wound healing following dental pulp injury.

Biological responses to flexion/extension in spinal segments ex-vivo.

Mechanical loading is a salient factor in the progression of spinal disorders that contribute to back pain. Biological responses to loading modes like flexion/extension (F/E) in relevant spinal tissues remain unstudied. A novel, multi-axial experimental system was developed to subject viable functional spinal units (FSUs) to complex, in-situ loading. The objective was to determine biological effects of F/E in multiple spinal tissues-annulus fibrosus, nucleus pulposus, facet cartilage, and ligamentum flavum. Rabbit lumbar FSUs were mounted in a bioreactor within a robotic testing system. FSUs underwent small (0.17/0.05 Nm) and large (0.5/0.15 Nm) range-of-motion F/E for 1 or 2 h of cycling. Outcomes in each tissue, compared to unloaded FSUs, included (i) relative mRNA expression of catabolic (MMP-1, 3 and ADAMTS-5), pro-inflammatory (COX-2), and anabolic (ACAN) genes and (ii) immunoblotting of aggrecan degradation. Total energy applied to FSUs increased in groups subject to large range-of-motion and 2-h cycling, and moment relaxation was higher with large range-of-motion. F/E significantly modulated MMP1,-3 and COX-2 in facet cartilage and MMP-3 and ACAN in annulus fibrosus. Large range-of-motion loading increased MMP-mediated aggrecan fragmentation in annulus fibrosus. Biological responses to complex loading ex vivo showed variation among spinal tissues that reflect tissue structure and mechanical loading in F/E.

Polyphosphate induces matrix metalloproteinase-3-mediated proliferation of odontoblast-like cells derived from induced pluripotent stem cells.

Inorganic polyphosphate [Poly(P)] may represent a physiological source of phosphate and has the ability to induce bone differentiation in osteoblasts. We previously reported that cytokine-induced matrix metalloproteinase (MMP)-3 accelerates the proliferation of purified odontoblast-like cells. In this study, MMP-3 small interfering RNA (siRNA) was transfected into odontoblast-like cells derived from induced pluripotent stem cells to investigate whether MMP-3 activity is induced by Poly(P) and/or is associated with cell proliferation and differentiation into odontoblast-like cells. Treatment with Poly(P) led to an increase in both cell proliferation and additional odontoblastic differentiation. Poly(P)-treated cells showed a small but significant increase in dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) mRNA expression, which are markers of mature odontoblasts. The cells also acquired additional odontoblast-specific properties including adoption of an odontoblastic phenotype typified by high alkaline phosphatase (ALP) activity and a calcification capacity. In addition, Poly(P) induced expression of MMP-3 mRNA and protein, and increased MMP-3 activity. MMP-3 siRNA-mediated disruption of the expression of these effectors potently suppressed the expression of odontoblastic biomarkers ALP, DSPP, and DMP-1, and blocked calcification. Interestingly, upon siRNA-mediated silencing of MMP-3, we noted a potent and significant decrease in cell proliferation. Using specific siRNAs, we revealed that a unique signaling cascade, Poly(P)→MMP-3→DSPP and/or DMP-1, was intimately involved in the proliferation of odontoblast-like cells.

Polyphosphate-induced matrix metalloproteinase-3-mediated differentiation in rat dental pulp fibroblast-like cells.

Inorganic polyphosphate [Poly(P)] induces differentiation of osteoblastic cells. In this study, matrix metalloproteinase (MMP)-3 small interfering RNA (siRNA) was transfected into purified rat dental pulp fibroblast-like cells (DPFCs) to investigate whether MMP-3 activity induced by Poly(P) is associated with cell differentiation into osteogenic cells. Real-time quantitative polymerase chain reaction, western blotting, and an MMP-3 activity assay were used in this study. Poly(P) enhanced expression of mature odontoblast markers dentin sialophosphoprotein (DSPP) and dentin matrix protein (DMP)-1 in DPFCs. These cells also developed an osteogenic phenotype with increased expression of osteocalcin (OC) and osteopontin (OP), high alkaline phosphatase (ALP) activity, and an increased calcification capacity. Poly(P) induced the expression of MMP-3 mRNA and protein, and increased MMP-3 activity. MMP-3 siRNA potently suppressed the expression of osteogenic biomarkers ALP, OC, OP, DSPP, and DMP-1, and blocked osteogenic calcification. Taken together, Poly(P)-induced MMP-3 regulates differentiation of osteogenic cells from DPFCs.

IL-1ß-induced matrix metalloproteinase-3 regulates cell proliferation in rat dental pulp cells.

OBJECTIVE: We previously reported that matrix metalloproteinase-3(MMP-3) accelerates wound healing following dental pulp injury. In this study, we tested the hypothesis that induction of MMP-3 activity by interleukin-1ß would promote proliferation and apoptosis of dental pulp cells. MATERIALS AND METHODS: Dental pulp cells were isolated from rat incisors and subjected to interleukin-1ß. Matrix metalloproteinase-3 mRNA and protein expression were assessed using reverse transcription-polymerase chain reaction and Western blotting, respectively. Matrix metalloproteinase-3 activity was measured using fluorescence. Dental pulp cell proliferation and apoptosis were determined using enzyme-linked immunosorbent assays (ELISA) for BrdU and DNA fragmentation, respectively. siRNA was used to reduce MMP-3 transcripts in these cells. RESULTS: Treatment with interleukin-1ß increased MMP-3 mRNA and protein levels as well as its activity in dental pulp cells. Cell proliferation was also markedly increased, with no changes in apoptosis observed. Treatment with siRNA against MMP-3 potently suppressed this interleukin-1ß-induced increase in MMP-3 expression and activity, and also suppressed cell proliferation but unexpectedly increased apoptosis in these cells (P < 0.05). This siRNA-mediated increase in apoptosis could be reversed with exogenous MMP-3 stimulation (P < 0.05). CONCLUSIONS: Interleukin-1ß induces MMP-3-regulated cell proliferation and suppresses apoptosis in dental pulp cells.

Endarteritis obliterans in the pathogenesis of Buerger's disease from the pathological and immunohistochemical points of view.

Buerger's disease (thromboangiitis obliterans) is considered to be a nonatherosclerotic, inflammatory, and vaso-occlusive disease, although the details of the mechanisms of pathogenesis remain unknown. The occurrence of the disease is strongly related to tobacco abuse and its progression is closely linked to continued smoking. The purpose of this review article is to demonstrate the pathological characteristics of arteries affected with Buerger's disease from a possible immunoreactive point of view. In addition, we present the mechanisms for preserving the architecture of the arterial wall in affected vasculatures. Thereafter, we discuss the possibility that the pathogenesis of Buerger's disease is a type of endarteritis obliterans, deeply connected to the Notch pathway, distinct from arteriosclerosis obliterans and other vasculitides.

Upregulation of serum vascular endothelial growth factor and matrix metalloproteinase-3 in patients with oral squamous cell carcinoma.

Vascular endothelial growth factor (VEGF) is known as a fundamental regulator of angiogenesis that accelerates cellular proliferation, vascular permeability, and endothelial cell migration and is an inhibitor of apoptosis. Extracellular matrix degradation by matrix metalloproteinase (MMP) is necessary for endothelial cell proliferation, migration, and metastasis. Accordingly, the objective of the present study was to determine the circulating levels of VEGF and MMP3 and their relation in patients with oral squamous cell carcinoma. Using an ELISA kit, the circulating levels of VEGF and MMP-3 in the sera of 45 patients with oral squamous cell carcinoma (OSCC) and 45 healthy controls were assessed. Mean VEGF levels in the sera of patients with OSCC (122.4 ± 36.1) were significantly higher than those in controls (65.3 ± 23.4); however, no relation was found between VEGF levels and clinicopathologic factors. The serum MMP-3 level in OSCC patients was significantly higher (9.45 ± 4.6 ng/ml, n=45) than that in healthy controls (5.9 ± 3.6 ng/ml, n=45). There was no correlation in serum MMP-3 concentration with clinicopathologic features such as tumor stage, tumor size, nodal status, and histological grade. A significant relationship was found between serum levels of VEGF and MMP3. This study concludes that VEGF and MMP3 may have a potential role in the pathogenesis of OSCC but cannot be used as a tool for monitoring tumor progression. Moreover, the role of VEGF in the regulation of angiogenesis is in part due to activation of MMP-3.

Cytokines induce MMP-3-regulated proliferation of embryonic stem cell-derived odontoblast-like cells.

OBJECTIVES: Matrix metalloproteinase (MMP)-3 expression increases after pulpectomy and accelerates angiogenesis in rat dental pulp by an uncharacterised mechanism. Odontoblasts, a major component of dental pulp, could represent a therapeutic target. We investigated whether MMP-3 activity is induced by cytokines and/or is associated with cell proliferation and apoptosis in embryonic stem cell-derived odontoblast-like cells. MATERIALS AND METHODS: We used reverse transcriptase polymerase chain reaction, western blotting, an MMP-3 activity assay, a BrdU-cell proliferation enzyme-linked immunosorbent assay and DNA fragmentation analysis to evaluate siRNA-mediated downregulation of MMP-3 expression and activity, and any changes in the proliferative and apoptotic responses associated with this reduced expression. RESULTS: Pro-inflammatory cytokines (interleukin-1ß, tumour necrosis factor-α and interferon-γ, at relatively low concentrations) induced MMP-3 mRNA and protein expression, and increased MMP-3 activity and cell proliferation, but not apoptosis. MMP-3 silencing produced a potent and significant suppression of cytokine-induced MMP-3 expression and activity, decreased cell proliferation and increased apoptosis. These effects were rescued by application of exogenous MMP-3. CONCLUSIONS: Our results suggest that pro-inflammatory cytokines induce MMP-3-regulated cell proliferation and anti-apoptosis effects in odontoblast-like cells derived from embryonic stem cells, in addition to their well-documented destructive role in inflammation.

Early events of overused supraspinatus tendons involve matrix metalloproteinases and EMMPRIN/CD147 in the absence of inflammation.

BACKGROUND: The principal feature of tendon degeneration is structural change of the extracellular matrix (ECM) including collagens. In painful tendons, alterations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been described; however, the initial molecular mechanism at the origin of these alterations is still poorly understood. A rat model of supraspinatus tendon overuse has been developed, which may be predictive of pathological tendon alterations. PURPOSE: To determine which MMPs are involved in early ECM remodeling during overuse and their relationship with the inflammatory context. STUDY DESIGN: Controlled laboratory study. METHODS: Analyses were performed on rat supraspinatus tendons at 2 and 4 weeks of overuse on a downhill treadmill. Transcript levels of MMPs and TIMPs were assessed by semiquantitative reverse transcription polymerase chain reaction. Western blotting and/or immunolabeling were used for MMP-2, MMP-3, MMP-13, and extracellular MMP inducer (EMMPRIN, also called cluster of differentiation [CD] 147) detection. In situ and/or sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gelatin zymography was performed for MMP-2 and MMP-9. TIMP activity was revealed by reverse zymography. Inflammation was assessed by cytokine antibody array and/or immunolabeling. RESULTS: Compared with a control, overused supraspinatus tendons showed a significantly higher gelatinolytic activity at 2 weeks, which slightly decreased at 4 weeks. MMP-9 and MMP-13 were undetectable; MMP-3 was downregulated in overused tendons. Only MMP-2, particularly its active form, and the MMP-2 activator MMP-14 were upregulated at 2 weeks of overuse when an increase in TIMP-2 transcripts was observed. MMP-2 upregulation occurred in the absence of inflammation but was associated with an increase of EMMPRIN/CD147. CONCLUSION: EMMPRIN/CD147-regulated MMP-2 and MMP-14, associated with low MMP-3, appear as the main characteristics of ECM remodeling in early overused tendons. Whether alterations in the pattern of these MMPs are an adaptive response or a repair response that may degenerate into tendinosis, is still uncertain. Moreover, there seems to be no indication for an inflammatory response to overuse, suggesting that the increased metalloproteinase activity is rather a response to a mechanical stress than an inflammatory one. CLINICAL RELEVANCE: Any strategy aimed at preventing full-thickness tears resulting from initial tendon matrix alterations should consider these changes in MMP-3, MMP-2, and MMP-14, or further upstream, EMMPRIN.

MMP-3 mediates psychosine-induced globoid cell formation: implications for leukodystrophy pathology.

Globoid cell leukodystrophy (GLD) or Krabbe disease, is a fatal demyelinating disease attributed to mutations in the galactocerebrosidase (GALC) gene. Loss of function mutations in GALC result in accumulation of the glycolipid intermediate, galactosylsphingosine (psychosine). Due to the cytotoxicity of psychosine, it has been hypothesized that accumulated psychosine underlie the pathophysiology of GLD. However, the cellular mechanisms of GLD pathophysiology remain unclear. Globoid cells, multinucleated microglia/macrophages in the central nervous system (CNS), are a defining characteristic of GLD. Here we report that exposure of primary glial cultures to psychosine induces the expression and the production of matrix metalloproteinase (MMP)-3 that mediated a morphological transformation of microglia into a multinucleated globoid cell type. Additionally, psychosine-induced globoid cell formation from microglia was prevented by either genetic ablation or chemical inhibition of MMP-3. These effects are microglia-specific as peripheral macrophages exposed to psychosine did not become activated or express increased levels of MMP-3. In the brain from twitcher mice, a murine model of human GLD, elevated MMP-3 expression relative to wild-type littermates was contemporaneous with disease onset and further increased with disease progression. Further, bone marrow transplantation (BMT), currently the only therapeutically beneficial treatment for GLD, did not mitigate the elevated expression of MMP-3 in twitcher mice. Hence, elevated expression of MMP-3 in GLD may promote microglial responses to psychosine that may represent an important pathophysiological process in this disease and its treatment.

Matrix metalloproteinase-3 in the central nervous system: a look on the bright side.

Matrix metalloproteinases (MMPs) are a large family of proteases involved in many cell-matrix and cell-cell signalling processes through activation, inactivation or release of extracellular matrix (ECM) and non-ECM molecules, such as growth factors and receptors. Uncontrolled MMP activities underlie the pathophysiology of many disorders. Also matrix metalloproteinase-3 (MMP-3) or stromelysin-1 contributes to several pathologies, such as cancer, asthma and rheumatoid arthritis, and has also been associated with neurodegenerative diseases like Alzheimer's disease, Parkinson's disease and multiple sclerosis. However, based on defined MMP spatiotemporal expression patterns, the identification of novel candidate molecular targets and in vitro and in vivo studies, a beneficial role for MMPs in CNS physiology and recovery is emerging. The main purpose of this review is to shed light on the recently identified roles of MMP-3 in normal brain development and in plasticity and regeneration after CNS injury and disease. As such, MMP-3 is correlated with neuronal migration and neurite outgrowth and guidance in the developing CNS and contributes to synaptic plasticity and learning in the adult CNS. Moreover, a strict spatiotemporal MMP-3 up-regulation in the injured or diseased CNS might support remyelination and neuroprotection, as well as genesis and migration of stem cells in the damaged brain.