Ten years in the life of an enzyme: the story of the human MMP-13 (collagenase-3)

Effects of Water-Ethanol Extracts from Four Sphagnum Species on Gene Expression of Selected Enzymes in Normal Human Dermal Fibroblasts and Their Antioxidant Properties

Mosses (Bryophyta), particularly species of the genus Sphagnum, which have been used for centuries for the treatment of skin diseases and damage, are still not explored enough in terms of their use in cosmetics. The purpose of this study was to determine the antioxidant properties of water-ethanol extracts from four selected species of the genus Sphagnum (S. girgenshonii Russow, S. magellanicum Brid., S. palustre L., and S. squarrosum Crome) and their impact on the expression of genes encoding key enzymes for the functioning of the skin. In this study, the effects of Sphagnum extracts on the expression of genes encoding tyrosinase, collagenase, elastase, hyaluronidase and hyaluronic acid synthase in human dermal fibroblasts were determined for the first time in vitro. The extracts inhibited tyrosinase gene expression and showed antioxidant activity. The experiment showed an increase in the expression of some genes encoding collagenase (MMP1) or hyaluronidase (HYAL2, HYAL3 and HYAL4) and a decrease in the hyaluronan synthase (HAS1, HAS2 and HAS3) genes expression by the tested extracts. The obtained results suggest that using extracts from the tested Sphagnum species in anti-aging cosmetics does not seem beneficial. Further studies are needed to clarify their impact on the skin.

Matrix metalloproteinase profiling and their roles in disease

Matrix metalloproteinases (MMPs) play roles in remodelling of the extracellular matrix that occurs during morphogenesis, repair, and angiogenesis. Dysregulation of extracellular matrix remodelling can lead to cell proliferation, invasion, and tissue fibrosis. Identification of a specific MMP(s) in a disease has been challenging due to the presence of 24 closely-related human MMPs, each existing in three forms, of which only one is active and capable of catalysis. This review focuses on methods for MMP profiling, with particular emphasis on the batimastat affinity resin that binds only to the active forms of MMPs and related ADAMs (a disintegrin and metalloproteinases), which are then identified by mass spectrometry. Use of the batimastat affinity resin has identified targets for intervention in several human diseases.

Regulation of transforming growth factor-β1-stimulation of Runx2 acetylation for matrix metalloproteinase 13 expression in osteoblastic cells

Transforming growth factor beta 1 (TGF-β1) functions as a coupling factor between bone development and resorption. Matrix metalloproteinase 13 (MMP13) is important in bone remodeling, and skeletal dysplasia is caused by a deficiency in MMP13 expre-ssion. Runx2, a transcription factor is essential for bone development, and MMP13 is one of its target genes. TGF-β1 promoted Runx2 phosphorylation, which was necessary for MMP13 production in osteoblastic cells, as we previously shown. Since the phosphorylation of some proteins causes them to be degraded by the ubiquitin/proteasome pathway, we hypothesized that TGF-β1 might stabilize the phosphorylated Runx2 protein for its activity by other post-translational modification (PTM). This study demonstrated that TGF-β1-stimulated Runx2 acetylation in rat osteoblastic cells. p300, a histone acetyltransferase interacted with Runx2, and it promoted Runx2 acetylation upon TGF-β1-treatment in these cells. Knockdown of p300 decreased the TGF-β1-stimulated Runx2 acetylation and MMP13 expression in rat osteoblastic cells. TGF-β1-treatment stimulated the acetylated Runx2 bound at the MMP13 promoter, and knockdown of p300 reduced this effect in these cells. Overall, our studies identified the transcriptional regulation of MMP13 by TGF-β1 via Runx2 acetylation in rat osteoblastic cells, and these findings contribute to the knowledge of events presiding bone metabolism.

The Role of Matrix Metalloproteinases (MMP-8, MMP-9, MMP-13) in Periodontal and Peri-Implant Pathological Processes

Severe periodontitis, a destructive inflammatory disease of the supporting tissues of the teeth, ranks sixth in terms of global spread, affecting about 11% of the population. Metalloproteinases (MMPs) are extracellular matrix (ECM) macromolecules that are important in cellular development and morphogenesis, and they are capable of activating growth factors in their proximity, cell surface receptors, and adhesion molecules. MMPs are part of a major family of zinc-dependent endopeptidases, and their activity is modulated and regulated by certain inhibitors known as tissue metalloproteinase inhibitors (TIMPs). Because type I collagen is the major component of the periodontal extracellular matrix, special attention has been paid to the role of collagenases, especially MMP-8 and MMP-13 and gelatinases, MMP-2 and MMP-9, in periodontal diseases. In fact, MMP-8 (or collagenase 2) is currently one of the most promising biomarkers for periodontitis in oral fluids. Among them, salivary MMP-9 has been shown to be a more sensitive marker for periodontal inflammation during orthodontic treatment, which opens new perspectives in reducing periodontal hazards during such treatments. Both MMP-8 and MMP-9 are extremely valuable diagnostic tools in treating periodontitis, and future studies and healthcare policies should focus on implementing more accessible methods of chairside testing in order to reduce the prevalence of this disease.

Aortic intimal resident macrophages are essential for maintenance of the non-thrombogenic intravascular state

Leukocytes and endothelial cells frequently cooperate to resolve inflammatory events. In most cases, these interactions are transient in nature and triggered by immunological insults. Here, we report that in areas of disturbed blood flow, aortic endothelial cells permanently and intimately associate with a population of specialized macrophages that are recruited at birth from the closing ductus arteriosus and share the luminal surface with the endothelium becoming interwoven in the tunica intima. Anatomical changes that affect hemodynamics, like in patent ductus arteriosus, alter macrophage seeding to coincide with regions of disturbed flow. Aortic resident macrophages expand in situ via direct cell renewal. Induced-depletion of intimal macrophages led to thrombin-mediated endothelial cell contraction, progressive fibrin accumulation and formation of microthrombi that, once dislodged, caused blockade of vessels in several organs. Together the findings revealed that intravascular resident macrophages are essential to regulate thrombin activity and clear fibrin deposits in regions of disturbed blood flow.

Phloretin, an Apple Polyphenol, Inhibits Pathogen-Induced Mucin Overproduction

SCOPE

Bacterial infection induces mucus overproduction, contributing to acute exacerbations and lung function decline in chronic respiratory diseases. A diet enriched in apples may provide protection from pulmonary disease development and progression. This study examined whether phloretin, an apple polyphenol, inhibits mucus synthesis and secretion induced by the predominant bacteria associated with chronic respiratory diseases.

METHODS AND RESULTS

The expression of mucus constituent mucin 5AC (MUC5AC) in FVB/NJ mice and NCI-H292 epithelial cells is analyzed. Nontypeable Haemophilus influenzae (NTHi)-infected mice developed increased MUC5AC mRNA, which a diet containing phloretin inhibited. In NCI-H292 cells, NTHi, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa increased MUC5AC mRNA, which phloretin inhibited. Phloretin also diminished NTHi-induced MUC5AC protein secretion. NTHi-induced increased MUC5AC required toll-like receptor 4 (TLR4) and NADH oxidase 4 (NOX4) signaling and subsequent activation of the epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) pathway. Phloretin inhibited NTHi-induced TLR4/NOX4 and EGFR/MAPK signaling, thereby preventing increased MUC5AC mRNA. EGFR activation can also result from increased EGFR ligand synthesis and subsequent ligand activation by matrix metalloproteinases (MMPs). In NCI-H292 cells, NTHi increased EGFR ligand and MMP1 and MMP13 mRNA, which phloretin inhibited.

CONCLUSIONS

In summary, phloretin is a promising therapeutic candidate for preventing bacterial-induced mucus overproduction.

Site-Dependent Lineage Preference of Adipose Stem Cells

Adult stem cells have unique properties in both proliferation and differentiation preference. In this study, we hypothesized that adipose stem cells have a depot-dependent lineage preference. Four rabbits were used to provide donor-matched adipose stem cells from either subcutaneous adipose tissue (ScAT) or infrapatellar fat pad (IPFP). Proliferation and multi-lineage differentiation were evaluated in adipose stem cells from donor-matched ScAT and IPFP. RNA sequencing (RNA-seq) and proteomics were conducted to uncover potential molecular discrepancy in adipose stem cells and their corresponding matrix microenvironments. We found that stem cells from ScAT exhibited significantly higher proliferation and adipogenic capacity compared to those from donor-matched IPFP while stem cells from IPFP displayed significantly higher chondrogenic potential compared to those from donor-matched ScAT. Our findings are strongly endorsed by supportive data from transcriptome and proteomics analyses, indicating a site-dependent lineage preference of adipose stem cells.

TGF-β1-stimulation of matrix metalloproteinase-13 expression by down-regulation of miR-203a-5p in rat osteoblasts

Transforming growth factor-beta1 (TGF-β1) is a pleiotropic and ubiquitous cytokine involved in bone development and bone remodeling. Matrix metalloproteinase-13 (MMP13) plays a role in the degradation of the extracellular matrix (ECM), and the regulation of this gene is critical in bone remodeling. We previously reported that TGF-β1 stimulates MMP13 expression in rat osteoblasts. Recently, studies have examined the regulation of bone metabolism by microRNAs (miRNAs) to determine their therapeutic potential in osteogenesis. Here, we assessed the effect of TGF-β1 on down-regulation of miRNAs that target MMP13 and stimulation of MMP13 expression in osteoblasts. We used in silico analysis and identified 11 specific miRNAs which directly target rat MMP13. Among these miRNAs, miR-203a-5p expression was significantly decreased by TGF-β1-treatment in rat osteoblasts. Transient transfection of a miR-203a-5p mimic into rat osteoblasts reduced MMP13 expression. A luciferase reporter assay confirmed a direct targeting of miR-miR-203a-5p with the 3' untranslated regions of the MMP13 gene. Hence, we suggest that TGF-β1 stimulated down-regulation of miR-203a-5p, resulting in the stimulation of MMP13 expression in rat osteoblasts. Thus, identification of the role of miR-203a-5p via TGF-β1 and MMP13 in bone remodeling indicated its potential as a biomarker or therapeutic agent for treating bone and bone-related diseases.

ZnO nanoparticles inhibit the activity of Porphyromonas gingivalis and Actinomyces naeslundii and promote the mineralization of the cementum

Background

Zinc oxide nanoparticles (ZnONPs) have been widely studied as bactericidal reagents. However, it is still challenging to use ZnONPs as a root canal sealant to eliminate infecting microorganisms in the root canal system. This study aimed at understanding the antibacterial and biofilm effects of ZnONPs in the infected root canal and their effect on cell function.

Methods

This study aimed to develop a better understanding of the antibacterial effects of ZnONPs in the infected root canal and their effect on cell function. Experiments were performed in two stages; the first stage included inhibition zone tests and the minimum inhibitory concentration (MIC) test, which were performed to examine the antibacterial activity of ZnONPs against Porphyromonas gingivalis (P. gingivalis) and Actinomyces Naeslundii (A. naeslundii) bacteria in vitro. ZnONPs were further evaluated for their biocompatibility using normal mouse NIH3T3 and OCCM-30 cells by the cell-based MTT assay. In addition, the influence of ZnONPs on matrix metalloproteinases in NIH3T3 cells and their inhibiting factors (Mmp13 and Timp1) were measured using the real-time PCR technique and western blot method.

Results

The MIC of ZnONPs against P. gingivalis and A. naeslundii were confirmed to be 10 μg/mL and 40 μg/mL, respectively. The MTT assay showed that ZnONPs were nontoxic. The RT-PCR and western blotting results showed that Mmp13 was downregulated and Timp1 expression was increased. Meanwhile, ZnONPs were shown to increase the expression of the OCCM-30 osteogenesis-related factors Bsp and Runx2. Finally, there was no significant change in the morphology of NIH3T3 and OCCM-30 cells after the addition of different concentrations of ZnONPs for different periods of time.

Conclusion

ZnONPs have excellent antibacterial activity against P. gingivalis and A. naeslundii and have low cell cytotoxicity in vitro.

Delayed resolution of bleomycin-induced pulmonary fibrosis in absence of MMP13 (collagenase 3)

Matrix metalloprotease 13 (MMP13) deficiency in pulmonary fibrosis has described contradictory phenotypes on inflammatory and fibrotic responses after lung injury, and its role during lung fibrosis resolution is still undefined. MMP13 has been considered the main collagenase in rodents, and the remodeling of fibrillar collagen is widely attributed to the action of this enzyme. In this study we aimed to explore the role of MMP13 during lung fibrosis progression and resolution. Lung fibrosis was induced by intratracheal instillation, and inflammatory, fibrotic, and resolution stages were evaluated in Mmp13-null and wild-type (WT) mice. Bronchoalveolar lavage fluid was taken for cytokine array analysis and activity of gelatinases. Our results showed that MMP13 is upregulated mainly during two stages after lung injury, inflammation and resolution of fibrosis, and it is mainly expressed by alveolar and interstitial macrophages. Mmp13-null mice exhibited more extensive inflammation at 7 days after bleomycin treatment, and it was characterized by increased macrophage infiltration and significant alterations in proinflammatory cytokines. We also documented that Mmp13-deficient mice experienced more severe and prolonged lung fibrosis compared with WT mice. Delayed resolution in Mmp13-deficient lungs was characterized by a decreased overall collagenolytic activity and persistent fibrotic foci associated with emphysema-like areas. Together, our findings indicate that MMP13 plays an antifibrotic role and its activity is crucial in lung repair and restoration of tissue integrity during fibrosis resolution.

Adjunctive Effects of a Sub-Antimicrobial Dose of Doxycycline on Clinical Parameters and Potential Biomarkers of Periodontal Tissue Catabolism

Objectives: The aim of the present randomized, double-blind, placebo-controlled, parallel-arm study was to examine the effectiveness of a sub-antimicrobial dose of doxycycline (SDD) in combination with nonsurgical periodontal therapy, compared to nonsurgical periodontal therapy alone, on potential gingival crevicular fluid (GCF) biomarkers of periodontal tissue catabolism related to the clinical outcomes over a 12-month period. Materials and Methods: GCF was collected and clinical parameters were recorded from 30 periodontitis patients randomized either to an SDD or placebo group. The SDD group received SDD (20 mg) b.i.d for 3 months plus scaling and root planing (SRP), while the placebo group was given placebo capsules b.i.d for 3 months plus SRP. The patients were evaluated every 3 months during the 12-month study period. At each visit, clinical parameters and GCF sampling were repeated. Matrix metalloproteinase (MMP)-8, MMP-9, MMP-13, myeloperoxidase (MPO), osteoprotegerin (OPG), and tartrate-resistant acid phosphatase-5 (TRAP-5) were determined by IFMA and ELISA. Results: Significant improvements were observed in all clinical parameters in both groups over 12 months (p < 0.0125) while the SDD group showed significantly better reduction in gingival index (GI) and pocket depth and a gain in clinical attachment compared to the placebo group (p < 0.05). GCF MMP-8 and OPG levels significantly reduced in the SDD group compared to baseline (p < 0.05). GCF MMP-9 significantly decreased in both groups compared to baseline (p < 0.05). GCF MPO significantly decreased at 3 and 9 months in the SDD group, while it significantly decreased at 6 months in the placebo group (p < 0.05). TRAP and MMP-13 could be detected in none of the samples. Conclusions: The present results indicate that three months of adjunctive usage of SDD to nonsurgical periodontal therapy compared to nonsurgical periodontal therapy alone in periodontitis patients results in further improvement of clinical periodontal parameters and GCF markers of periodontal tissue breakdown over a 12-month period. Beneficial effects of adjunctive SDD therapy is likely to be related to the reduced levels of two major periodontitis-associated MMPs, MMP-8 and -9, and their potential oxidative activator MPO.

Potent and selective inhibition of matrix metalloproteinases by lanthanide trichloride

Matrix metalloproteinases (MMPs) are a family of Zn-containing and Ca-dependent proteases with vital roles in extracellular matrix remodeling. Deregulation of MMPs occurs in many pathological conditions such as cardiovascular diseases, inflammation, and cancer. The therapeutic potential of MMP inhibitors has been demonstrated in diseases such as arthritis and cancer. Here we demonstrated that the 3-valent lanthanide compounds LaCl₃, TbCl₃, GdCl₃, YbCl₃, and EuCl₃ inhibit MMPs such as MMP-2, MMP-13, and MMP-14 (MT1-MMP). The inhibition is more potent and selective toward MT1-MMP compared to the other MMPs. EuCl₃ was further selected to study the enzyme kinetics of the MT1-MMP inhibition. The results showed that the inhibition is a mixed type with anti-competition and non-competitive types, which indicated that inhibition was achieved by the compound bound to the non-active center of MT1-MMP and changing the enzyme conformation. The interaction between EuCl₃ and MT1-MMP was further studied by UV-visible (UV-vis) light absorption. EuCl₃ caused a slight blue shift of the maximum absorption wavelength of MT1-MMP, indicating the interaction reduced protein hydrophobicity. Moreover, EuCl₃ exerted substantial inhibitory effects on the migration of HT-1080 cells. Thus, EuCl₃ may play a role in modulating tumor cell behavior by inhibiting MMPs activities especially the MT1-MMP activity. These findings provide initial insight into the biological activity and potential therapeutic value of EuCl₃.

Priming anoestrous Corriedale ewes with progesterone and gonadotrophin-releasing hormone causes cervical tissue remodelling due to metalloproteinase-2 (MMP-2) activity

The aim was to obtain experimental evidence of cervical collagen degradation in anoestrous Corriedale adult ewes induced to ovulate with progesterone (P) and gonadotrophin-releasing hormone (GnRH), at the expected time of induced ovulation and early luteal phase. In Experiment 1, anoestrous ewes were treated with P for 10 days (P, n = 4), with nine micro-doses of GnRH followed by a GnRH bolus injection (GnRH, n = 4) or with P plus GnRH treatments (P+GnRH, n = 3), and cervices were obtained either without treatment (A, n = 4), when P was removed, or 24 h after the GnRH bolus injection. In Experiment 2, cervices were obtained 1 (group P+GnRH, n = 5) or 5 (P+GnRH 5, n = 6) days after the GnRH bolus injection with P pretreatment. MMP-2 activity was detected in all samples; however, MMP-9 activity was only detected in 15% of the samples. The activity of the latent (L) form of MMP-2 in the cranial zone of group A was higher than in the cranial zone of groups P, GnRH and P+GnRH, and was also higher than that in the caudal zone of the same group (P < 0.05). The collagen concentration was lower in group P+GnRH 1 than in group P+GnRH 5 (P < 0.04). The activity of the activated (A) form of MMP-2 and the A/L MMP-2 ratio were higher in group P+GnRH 1 than in group P+GnRH 5 (P < 0.05). Data suggest that the L form of MMP-2 was expressed mainly in a constitutive form in the cervix of anoestrous ewes and that an oestrogen-dependent activation mechanisms due to the GnRH treatment may be responsible for the lowest collagen content at the moment of the induced ovulation. This work provides evidence about cervical collagen remodelling in anoestrous ewes treated with P + GnRH.

Regulation of type II collagen, matrix metalloproteinase-13 and cell proliferation by interleukin-1β is mediated by curcumin via inhibition of NF-κB signaling in rat chondrocytes

Curcumin possesses strong anti-inflammatory, anti-rheumatoid and anti-oxidative activities, and has the potential to inhibit nuclear factor-κB (NF-κB) signaling. Cartilage damage in osteoarthritis (OA) is largely mediated by interleukin-1β (IL-1β) via activation of various transcription factors, including NF-κB and activator protein-1. The aim of the present study was to determine whether IL-1β induces matrix metalloproteinase-13 (MMP-13) expression and inhibits type II collagen expression, as well as to examine whether cell proliferation may be inhibited by curcumin through the inhibition of NF-κB signaling. The effects of curcumin were investigated in rat articular chondrocyte cell cultures treated with IL-1β in the presence or absence of curcumin or the NF-κB inhibitor pyrrolidine dithiocarbamate. Western blotting and reverse transcription-quantitative polymerase chain reaction were conducted to evaluate protein and mRNA expression levels of type II collagen, MMP-13, NF-κB inhibitor α (IκBα), phosphorylated-IκBα and NF-κB subunit p65/RelA. Western blotting and immunofluorescence were performed to examine the effects of curcumin on the expression, phosphorylation and nuclear translocation of NF-κB-associated proteins. The effects of curcumin on cell proliferation were evaluated by Cell Counting Kit-8 (CCK-8). Curcumin was demonstrated to inhibit the IL-1β-induced activation of NF-κB by suppressing IκBα phosphorylation and p65/RelA nuclear translocation. These events were associated with the downregulation of MMP-13 expression and the upregulation of type II collagen expression, both of which are considered to be NF-κB targets. CCK-8 assays revealed that co-treatment with curcumin resulted in increased proliferation in IL-1β-treated chondrocytes. These findings implicated curcumin as a naturally occurring anti-inflammatory agent for the treatment of OA via inhibition of NF-κB signaling.

Sirtuin 1 regulates matrix metalloproteinase-13 expression induced by Porphyromonas endodontalis lipopolysaccharide via targeting nuclear factor-κB in osteoblasts

Porphyromonas endodontalis lipopolysaccharide (P.e LPS) is an important initiating factor for periapical inflammation and bone destruction. Matrix metalloproteinase-13 (MMP-13) has been shown to participate in the formation and diffusion of periapical bone lesion in chronic apical periodontitis. Sirtuin 1 (SIRT1) is a key regulator of inflammation in mammalian cells which suppresses the release of inflammatory mediators. This study aimed to explore the role of SIRT1 in regulating MMP-13 expression induced by P.e LPS in osteoblasts. P.e LPS stimulated MMP-13 expression in MC3T3-E1 cells. Knockdown of SIRT1 reinforced the increase of MMP-13mRNA expression induced by P.e LPS. SIRT1 activator resveratrol significantly reduced the expression of MMP-13 and SIRT1 inhibitor EX-527 enhanced the expression of MMP-13. Moreover, SIRT1 activation with resveratrol inhibited acetylation of NF-κB p65 and NF-κB transcriptional activity, which were enhanced by P.e LPS. In addition, NF-κB p65 was involved in P.e LPS-induced MMP-13 expression via directly binding to the MMP-13 promoter. However, SIRT1 activation significantly interfered with this binding. These findings strongly suggest that P.e LPS induces MMP-13 expression in osteoblasts, and SIRT1 suppresses this expression of MMP-13 through targeting NF-κB p65. This provides new insights into understanding the actions of SIRT1 on anti-inflammatory and anti-bone resorption activity.

Host and tumor derived MMP13 regulate extravasation and establishment of colorectal metastases in the liver

BACKGROUND

Non alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in the United States and worldwide. Our studies have previously shown an increase in metastatic burden in steatotic vs. normal livers using a mouse model of diet induced steatosis. In the present study we aim to identify and evaluate the molecular factors responsible for this increase in tumor burden.

METHODS

We assessed changes in expression of a panel of matrix metalloproteinases (MMPs) using qRT-PCR between normal and steatotic livers and validated them with western blot analysis of protein levels. To evaluate the role of MMP13 on tumor development, we utilized a splenic injection model of liver metastasis in Wildtype and Mmp13 deficient mice, using either parental or stable Mmp13 knockdown cell lines. Further, to evaluate changes in the ability of tumor cells to extravasate we utilized whole organ confocal microscopy to identify individual tumor cells relative to the vasculature. MTT, migration and invasion assays were performed to evaluate the role of tumor derived MMP13 on hallmarks of cancer in vitro.

RESULTS

We found that MMP13 was significantly upregulated in the steatotic liver both in mice as well as human patients with NAFLD. We showed a decrease in metastatic tumor burden in Mmp13-/- mice compared to wildtype mice, explained in part by a reduction in the number of tumor cells extravasating from the hepatic vasculature in the Mmp13-/- mice compared to wildtype mice. Additionally, loss of tumor derived MMP13 through stable knockdown in tumor cell lines lead to decreased migratory and invasive properties in vitro and metastatic burden in vivo.

CONCLUSIONS

This study demonstrates that stromal as well as tumor derived MMP13 contribute to tumor cell extravasation and establishment of metastases in the liver microenvironment.

Potent selective inhibition of MMP-14 by chloroauric acid and its inhibitory effect on cancer cell invasion

Enzyme kinetics and Matrigel invasion assay indicated that the specific inhibition of HAuCl₄ on MMP-14 involves a non-competitive reversible inhibitory mechanism and HAuCl₄ inhibits HT-1080 cell invasion in a dose-dependent manner.

Decreased histone deacetylase 4 is associated with human osteoarthritis cartilage degeneration by releasing histone deacetylase 4 inhibition of runt-related transcription factor-2 and increasing osteoarthritis-related genes: a novel mechanism of human osteoarthritis cartilage degeneration

INTRODUCTION

To investigate if decreased histone deacetylase 4 (HDAC4) is associated with human osteoarthritis (OA) cartilage degeneration by releasing HDAC4 inhibition of runt-related transcription factor-2 (Runx2) resulting in increase of OA cartilage degeneration-related genes.

METHODS

The mRNA and protein levels of HDAC4, Runx2, matrix metalloproteinase (MMP)-13, Indian hedgehog (Ihh) and type X collagen were detected by performing real-time PCR (RT-PCR), western blotting and immunohistochemistry on specimens from human OA and normal cartilage. To further explore the mechanism of regulation of Runx2 and OA-related genes by HDAC4, changes in these OA-related genes were further quantified by RT-PCR after overexpression of HDAC4 and knockdown of HDAC4 by siRNA. Runx2 and MMP-13 promoter activities were measured by dual luciferase assays.

RESULTS

The levels of HDAC4 in the cartilage from OA patients and healthy 40- to 60-year-old donors were decreased to 31% and 65% compared with specimens from 20- to 40-year-old healthy donors, respectively (P <0.05). Decreased HDAC4 was associated with increased Runx2 and other OA-related genes in human OA cartilage, specifically: MMP-13, Ihh and type X collagen. Exogenous HDAC4 decreased the mRNA levels of Runx2, MMP1, MMP3, MMP-13, type X collagen, Ihh, ADAMTS-4 and -5, and increased the mRNA of type II collagen. In addition, the data also shows that overexpression of HDAC4 not only decreased the expression of interleukin (IL)-1β, Cox2 and iNos and increased the expression of aggrecan, but also partially blocked the effect of IL-1β on expression of catabolic events in human OA chondrocytes. HDAC4 also inhibited Runx2 promoter activity and MMP13 promotor activity in a dose-dependent manner. In contrast, inhibition of HDAC4 by TSA drug had an opposite effect.

CONCLUSIONS

Our study is the first to demonstrate that decreased HDAC4 contributes, at least in part, to the pathogenesis of OA cartilage degeneration. Thus, HDAC4 may have chondroprotective properties by inhibiting Runx2 and OA-related genes.

Expression of modulators of extracellular matrix structure after anterior cruciate ligament injury

The ability of the anterior cruciate ligament (ACL) to heal after injury declines within the first 2 weeks after ACL rupture. To begin to explore the mechanism behind this finding, we quantified the expression of genes for collagen I and III, decorin, tenascin-C, and alpha smooth muscle actin, as well as matrix metalloproteinase (MMP)-1 and -13 gene expression within multiple tissues of the knee joint after ACL injury in a large animal model over a 2-week postinjury period. Gene expression of collagen I and III, decorin, and MMP-1 was highest in the synovium, whereas the highest MMP-13 gene expression levels were found in the ACL. The gene expression for collagen and decorin increased over the 2 weeks to levels approaching that in the ligament and synovium; however, no significant increase in either of the MMPs was found in the provisional scaffold. This suggests that although the ACL and synovium up-regulate both anabolic and catabolic factors, the provisional scaffold is primarily anabolic in function. The relative lack of provisional scaffold formation within the joint environment may thus be one of the key reasons for ACL degradation after injury.

Effects of deer bone extract on the expression of pro-inflammatory cytokine and cartilage-related genes in monosodium iodoacetate-induced osteoarthritic rats

Deer bone extract has the potential to relieve the discomfort or the articular cartilaginous damage associated with osteoarthritic (OA) and may be useful as a natural supplement for OA treatment without serious side effects. We analyzed the expression of pro-inflammatory cytokine and cartilage-related genes in monosodium iodoacetate-induced OA rats. Increases in the levels of serum pro-inflammatory cytokines, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α were significantly inhibited by the administration of deer bone extract (p &lt; 0.05). Decreases in the expression of collagen type II (COL2) and tissue inhibitors of metalloproteinases (TIMPs) mRNAs in the cartilage were significantly inhibited by deer bone extract treatment (p &lt; 0.05). The deer bone extract significantly suppressed the expression of matrix metalloproteinases (MMPs) mRNAs in the cartilage. The deer bone extract induced the up-regulation of COL2 and TIMP mRNAs and the down-regulation of MMP mRNAs by suppressing the expression of pro-inflammatory cytokine mRNAs.

Common polymorphism in the MMP-13 gene may contribute to the risk of human cancers: a meta-analysis

Cancer was viewed to be driven by accumulating genetic abnormalities that generally include chromosomal abnormalities, mutations in tumor-suppressor genes, and oncogenes. The aim of this meta-analysis was to systematically summarize the possible associations between MMP-13 rs2252070 A>G variant and cancer risks. We systematically reviewed studies focusing on MMP-13 polymorphisms with human cancer susceptibility that were published before April 30, 2014. Relevant articles were identified through research of PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, CBM, and CNKI databases. All analyses were calculated using the Version 12.0 STATA software. Odds ratios (OR) and 95 % confidence interval (95 % CI) were calculated. Eleven independent case-control studies were included in the meta-analysis, which involved 3,465 patients with cancers and 4,073 healthy controls. The results identified a positive association between rs2252070 A>G polymorphism and susceptibility to cancer under five genetic models (all P < 0.05). Ethnicity subgroup analysis implied that significant difference was detected for rs2252070 A>G polymorphism with increased risk of cancers among Asians and Caucasians in majority of the groups. Our findings suggest significant association for MMP-13 rs2252070 A>G to increased susceptibility to human cancer, especially in the progression of lung carcinoma.

Platelet-rich plasma for managing pain and inflammation in osteoarthritis

Osteoarthritis (OA) is a common disease involving joint damage, an inadequate healing response and progressive deterioration of the joint architecture. Autologous blood-derived products, such as platelet-rich plasma (PRP), are key sources of molecules involved in tissue repair and regeneration. These products can deliver a collection of bioactive molecules that have important roles in fundamental processes, including inflammation, angiogenesis, cell migration and metabolism in pathological conditions, such as OA. PRP has anti-inflammatory properties through its effects on the canonical nuclear factor κB signalling pathway in multiple cell types including synoviocytes, macrophages and chondrocytes. PRP contains hundreds of different molecules; cells within the joint add to this milieu by secreting additional biologically active molecules in response to PRP. The net results of PRP therapy are varied and can include angiogenesis, the production of local conditions that favour anabolism in the articular cartilage, or the recruitment of repair cells. However, the molecules found in PRP that contribute to angiogenesis and the protection of joint integrity need further clarification. Understanding PRP in molecular terms could help us to exploit its therapeutic potential, and aid the development of novel treatments and tissue-engineering approaches, for the different stages of joint degeneration.

Characterization of opticin digestion by proteases involved in osteoarthritis development

OBJECTIVE

Opticin is a class III member of the small leucine-rich repeat proteoglycan (SLRP) family, produced in articular joint tissues. In normal and osteoarthritic (OA) cartilage, opticin is degraded. This study aimed to assess whether human cartilage opticin is degraded by the main proteases involved in OA pathophysiology, and to determine the protease cleavage sites of this SLRP.

METHODS

We analyzed the proteolytic activity of matrix metalloproteinases (MMPs)-1, -2, -3, -7, -8 and -9, and ADAMTS-4 and -5 on proteoglycan extracts from normal and moderately fibrillated OA human cartilage, and on recombinant human opticin. Opticin degradation was analyzed by Western blotting and cleavage sites were determined by sequence analysis.

RESULTS

All eight proteases digested opticin from proteoglycan extracts from both normal and OA samples, as well as recombinant human opticin, MMP-2 and MMP-7 are the proteases that degrade recombinant human opticin most efficiently. The opticin cleavage site determined for these MMPs was between the glycosylation and leucine-rich repeat domains. MMP-7 had two additional digestion sites near the N-terminal end of opticin.

CONCLUSION

Opticin is a substrate for several MMPs and aggrecanases involved during OA cartilage degradation, and seems to be a preferential substrate for MMP-7. The role of opticin in cartilage degeneration could be related to decreased levels of intact opticin, followed by its proteolytic degradation, which in turn may stimulate some of the modifications observed in the OA cartilage, such as neovascularisation and changes in the extracellular matrix.

Matrix metalloproteinase-13 (MMP-13) directly and indirectly promotes tumor angiogenesis

Matrix metalloproteinases (MMPs) are extracellular zinc-dependent endopeptidases involved in the degradation and remodeling of extracellular matrix in physiological and pathological processes. MMPs also have a role in cell proliferation, migration, differentiation, angiogenesis, and apoptosis. We previously identified cancer invasion-related factors by comparing the gene expression profiles between parent and the highly invasive clone of cancer cells. Matrix metalloproteinase-13 (MMP-13) was identified as a common up-regulated gene by cancer invasion-related factors. Although MMP-13 slightly promoted tumor invasion, we found that MMP-13 was involved in tumor angiogenesis. Conditioned medium from MMP-13-overexpressing cells promoted capillary formation of immortalized human umbilical vein endothelial cells. Furthermore, treatment with recombinant MMP-13 protein enhanced capillary tube formation both in vitro and in vivo. MMP-13-promoted capillary tube formation was mediated by activation of focal adhesion kinase and ERK. Interestingly, MMP-13 promoted the secretion of VEGF-A from fibroblasts and endothelial cells. By immunohistochemical analysis, we found a possible correlation between MMP-13 expression and the number of blood vessels in human cancer cases. In summary, these findings suggest that MMP-13 may directly and indirectly promote tumor angiogenesis.

Clinicopathological significance and prognostic value of MMP-13 expression in colorectal cancer

The purpose of this study was to evaluate the association of matrix metalloproteinase-13 (MMP-13) expression with clinicopathological features and prognosis in colorectal cancer (CRC) patients. CRC tissues and distal normal mucosa tissues of 158 CRC patients were detected by immunohistochemistry. The correlations between MMP-13 expression, the patients' clinicopathological features, and overall survival rate were analyzed. It was found that positive expression rate of MMP-13 in distal normal mucosa tissues was significantly lower than that in CRC tissues (36.7% vs 60.8%, p < 0.001). Poor histological differentiation, advanced clinical stage and lymph node metastasis were significantly correlated with the MMP-13 expression in CRC. The overall survival rate of the MMP-13-negative group was significantly higher than the positive group (Log-rank test = 12.452, p < 0.001). Collectively, we found that MMP-13 was correlated with progression and metastasis of CRC and could be used as a prognostic marker in CRC.

The chemopreventive effect of mifepristone on mammary tumorigenesis is associated with an anti-invasive and anti-inflammatory gene signature

Progesterone receptor (PR) antagonists are potent antitumor agents in carcinogen and progestin-dependent mammary tumorigenesis models through both PR- and non-PR-mediated mechanisms. The PR antagonist mifepristone/RU486 has been used primarily as an abortifacient possessing high affinity for both the PR and glucocorticoid receptors (GR). To determine whether mifepristone would be effective as a chemopreventive agent, we assessed its effect on progestin/7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinogenesis in wild-type (WT) and estrogen receptor-α-positive (ER(+)) transgenic mice expressing the dominant-negative Pax8PPARγ (Pax8) fusion protein. Mifepristone administered at a dose of 2.5 mg significantly delayed mammary tumorigenesis in WT, but not in Pax8 mice, whereas, a three-fold higher dose almost completely blocked tumorigenesis in both WT and Pax8 mice. The sensitivity of WT mice to 2.5 mg mifepristone correlated with an expression profile of 79 genes in tumors, 52 of which exhibited the opposite response in Pax8 mice, and corresponded primarily to the downregulation of genes associated with metabolism, inflammation, and invasion. These results suggest that the chemopreventive activity of mifepristone in WT mice correlates with a specific gene expression signature that is associated with multiple nuclear receptor signaling pathways.

An MMP13-selective inhibitor delays primary tumor growth and the onset of tumor-associated osteolytic lesions in experimental models of breast cancer

We investigated the effects of the matrix metalloproteinase 13 (MMP13)-selective inhibitor, 5-(4-{4-[4-(4-fluorophenyl)-1,3-oxazol-2-yl]phenoxy}phenoxy)-5-(2-methoxyethyl) pyrimidine-2,4,6(1H,3H,5H)-trione (Cmpd-1), on the primary tumor growth and breast cancer-associated bone remodeling using xenograft and syngeneic mouse models. We used human breast cancer MDA-MB-231 cells inoculated into the mammary fat pad and left ventricle of BALB/c Nu/Nu mice, respectively, and spontaneously metastasizing 4T1.2-Luc mouse mammary cells inoculated into mammary fat pad of BALB/c mice. In a prevention setting, treatment with Cmpd-1 markedly delayed the growth of primary tumors in both models, and reduced the onset and severity of osteolytic lesions in the MDA-MB-231 intracardiac model. Intervention treatment with Cmpd-1 on established MDA-MB-231 primary tumors also significantly inhibited subsequent growth. In contrast, no effects of Cmpd-1 were observed on soft organ metastatic burden following intracardiac or mammary fat pad inoculations of MDA-MB-231 and 4T1.2-Luc cells respectively. MMP13 immunostaining of clinical primary breast tumors and experimental mice tumors revealed intra-tumoral and stromal expression in most tumors, and vasculature expression in all. MMP13 was also detected in osteoblasts in clinical samples of breast-to-bone metastases. The data suggest that MMP13-selective inhibitors, which lack musculoskeletal side effects, may have therapeutic potential both in primary breast cancer and cancer-induced bone osteolysis.

Distal interleukin-1β (IL-1β) response element of human matrix metalloproteinase-13 (MMP-13) binds activator protein 1 (AP-1) transcription factors and regulates gene expression

The collagenase matrix metalloproteinase-13 (MMP-13) plays an important role in the destruction of cartilage in arthritic joints. MMP-13 expression is strongly up-regulated in arthritis, largely because of stimulation by inflammatory cytokines such as IL-1β. Treatment of chondrocytes with IL-1β induces transcription of MMP-13 in vitro. IL-1β signaling converges upon the activator protein-1 transcription factors, which have been shown to be required for IL-1β-induced MMP-13 gene expression. Using chromatin immunoprecipitation (ChIP), we detected activator protein-1 binding within an evolutionarily conserved DNA sequence ∼20 kb 5' relative to the MMP-13 transcription start site (TSS). Also using ChIP, we detected histone modifications and binding of RNA polymerase II within this conserved region, all of which are consistent with transcriptional activation. Chromosome conformation capture indicates that chromosome looping brings this region in close proximity with the MMP-13 TSS. Finally, a luciferase reporter construct driven by a component of the conserved region demonstrated an expression pattern similar to that of endogenous MMP-13. These data suggest that a conserved region at 20 kb upstream from the MMP-13 TSS includes a distal transcriptional response element of MMP-13, which contributes to MMP-13 gene expression.

GCF and serum myeloperoxidase and matrix metalloproteinase-13 levels in renal transplant patients

AIM

The rationale of this study was to address whether local or systemic changes reflect proteolytic (matrix metalloproteinase-13) or oxidative (myeloperoxidase) stress in renal transplant patients receiving cyclosporine-A (CsA) and having gingival overgrowth (GO), in patients receiving CsA therapy and having no GO and patients receiving tacrolimus therapy.

MATERIAL AND METHODS

Gingival crevicular fluid (GCF) samples were collected from sites with (GO+) and without GO (GO-) in CsA patients having GO; GO- sites in CsA patients having no GO; sites from tacrolimus, gingivitis and healthy subjects. GCF and serum myeloperoxidase (MPO) and matrix metalloproteinase-13 (MMP-13) levels were determined by ELISA.

RESULTS

GO+ sites in CsA patients having GO had elevated GCF MPO levels than those of CsA patients having no GO, tacrolimus and healthy subjects (p<0.005), but comparable to those of gingivitis. GCF MPO levels were higher in GO+ compared to GO- sites in CsA patients having GO (p<0.05). Patient groups had similar, but higher GCF MMP-13 levels than healthy group.

CONCLUSIONS

These results show that CsA and tacrolimus therapy have not a significant effect on GCF MPO and MMP-13 levels, and gingival inflammation seems to be the main reason for their elevations.

Signal transduction and metabolism in chondrocytes is modulated by lactoferrin

OBJECTIVE

Activation of granulocytes causes a considerable rise in the concentration of lactoferrin (Lf) in synovial fluid (SF). We here investigate consequences thereof on signal transduction and the balance between catabolic and anabolic metabolism in chondrocytes.

METHODS

Signal transduction was analysed in cultured chondrocytes by immunodetection of mitogen activated protein kinases (MAPK) and analysis of Smad2 translocation to the nucleus. Expression levels of matrix metalloproteinases (MMPs) and of aggrecan were measured by reverse-transcription-PCR. The proteolytic activity of MMPs was ascertained by zymography. Expression of the low-density-lipoprotein-receptor-related-protein-1 (LRP-1), a Lf receptor for signalling, was assayed by immunohistochemistry in cartilage and in cultured chondrocytes by immunoblotting.

RESULTS

We found LRP-1 expressed in dedifferentiated chondrocytes in culture and in cartilage tissue preferentially on the articular surface where it can encounter Lf within SF. Lf stimulated proliferation of chondrocytes, comparable to transforming growth factor-beta1 (TGFbeta1) and activated p38 and the extracellular-signal regulated-kinases 1/2 (ERK1/2) within minutes. Surprisingly, Lf induced nuclear Smad2 translocation, a signal pathway ascribed to TGFbeta receptor activation. Lf significantly increased the levels of catabolic indicators such as MMP1, MMP2, MMP3 and MMP13 and inhibited aggrecan synthesis.

CONCLUSION

Lf is a robust regulator of chondrocyte metabolism, comparable to TGFbeta1. The catabolic influence together with the proliferative stimulus indicates a function as an early phase cytokine, enhancing MMPs, necessary for degradation of damaged tissue and stimulating proliferation of chondrocytes, necessary for reconstruction.

Reparo intraperitoneal de defeitos da parede ventral do abdome com telas de poliéster com colágeno e polipropileno com ácido poliglicólico

OBJETIVO: Avaliar a incorporação de telas de poliéster revestido em uma de suas faces por colágeno (Parietex, Covidien) e polipropileno recoberto por ácido poliglicólico (Optilene Mesh Elastic e Safil, BBD Aesculap) no reparo de defeitos da parede ventral de coelhos avaliando a cicatrização no aspecto macroscópico, o depósito de colágeno e a imunomarcação tecidual pelos anticorpos MMP-1, MMP-8 e MMP-13. MÉTODOS: Utilizaram-se 16 coelhos, divididos em dois grupos de oito animais, avaliados após eutanásia após 30 e 60 dias de pós-operatório. Os animais foram submetidos à realização de dois defeitos simétricos na parede ventral do abdome, à direita e esquerda da linha alba, que compreendendo todos os folhetos musculares e o peritônio. O reparo dos defeitos foi realizado mediante implante intraperitoneal de dois modelos diferentes de telas. Utilizou-se a tela de poliéster revestido com camada protetora de colágeno (grupo controle) e a tela de polipropilene revestido com malha de ácido poliglicólico (manufaturacao própria, grupo de experimentacao). A avaliacao constou de aspectos clínicos, achados macroscópicos, análise dos colágenos tipos I/III e avaliação imunoistoquímica de metaloproteinases. RESULTADOS: Os resultados da avaliacao clínica e os parâmetros macroscópicos foram semelhantes entre os grupos. 50% dos animais do grupo Parietex tiveram ausência de aderencias intraperitoneais a no 30° dia de pós-operatrório. Em ambos os grupos observou-se reducao das aderências entre o 30° e o 60° dias de pós-operatório, contudo sem diferenca estatística. As aderências observadas foram classificadas principalmente de frouxas. Nao se observou a ocorrencia de complicacoes envolvendo vísceras intraabdominais. No Grupo Parietex houve a ocorrência de formacao de ulceracao da pele que recobria a tela em quatro animais, em comparacao com um no grupo de experimentacao. No Grupo Parietex foi observada uma insuficiencia de reparo após 60 dias. Quanto ao depósito do colágeno tipos I e III, nao houve diferenca significativa entre os grupos. Os resultados da imunoistoquímica referentes aos anticorpos MMP-1 e MMP-8 também não demonstraram diferença significativa entre as telas. CONCLUSÃO: As duas telas pesquisadas obtiveram resultados semelhantes tanto nos aspectos macro como nos microscópicos, podendo ser consideradas semelhantes quanto ao reparo de defeitos cirúrgicos da parede ventral do abdome em coelhos.

Identification of opticin, a member of the small leucine-rich repeat proteoglycan family, in human articular tissues: a novel target for MMP-13 in osteoarthritis

OBJECTIVE

One of the proteoglycan families is the small leucine-rich proteoglycans (SLRPs) that are characterized by their association with collagen fibrils and/or some glycosaminoglycans. Opticin is a glycoprotein and class III member of the SLRP family, which was initially identified in the vitreous humour of the eye. In this study, we first investigated whether opticin is expressed and produced in normal and OA human articular tissues/cells. Further, we investigated the ability of the key metalloprotease involved in cartilage pathology, MMP-13, to cleave human cartilage opticin.

METHODS

Opticin gene expression was investigated in normal and OA human chondrocytes, synovial fibroblasts, and subchondral bone osteoblasts by reverse transcriptase-polymerase chain reaction (RT-PCR). Opticin protein production was determined in normal and OA synovial membrane and cartilage by immunohistochemistry. Opticin was isolated from human cartilage using guanidinium chloride extraction, and human MMP-13-induced opticin degradation analyzed by Western blotting. Finally, the opticin MMP-13 cleavage site was determined.

RESULTS

Opticin was expressed in human chondrocytes, synovial fibroblasts and subchondral osteoblasts, and the protein identified in synovial membrane and cartilage. At the protein level, OA cartilage showed a slightly higher level of opticin positive stained chondrocytes than normal cartilage; this did not reach statistical significance. However, in contrast with OA, normal cartilage demonstrated a high level of matrix staining in the superficial zone of the tissue, suggesting that in the OA cartilage matrix, opticin is degraded. Data also showed that cartilage opticin could be cleaved by MMP-13 after only 2h of incubation, indicating a preferential substrate compared to other SLRPs for this enzyme. Microsequencing revealed a major cleavage site at the G(104)/L(105)LAAP and a minor at P(109)/A(110)NHPG upon MMP-13 exposure.

CONCLUSION

We demonstrated, for the first time, that opticin is expressed and produced in human articular tissues. Our data also showed that opticin in OA cartilage is degraded in a process that could be mediated by MMP-13. As opticin may contribute towards the structural stability of cartilage, its cleavage by MMP-13 may predispose cartilage to degeneration, particularly at the surface.

The enhancement of chondrogenic differentiation of human mesenchymal stem cells by enzymatically regulated RGD functionalities

A thiol-acrylate photopolymerization was used to incorporate enzymatically cleavable peptide sequences into PEG hydrogels to induce chondrogenic differentiation of encapsulated human mesenchymal stem cells (hMSCs). An adhesive sequence, RGD, was designed with an MMP-13 specific cleavable linker. RGD promotes survival of hMSCs encapsulated in PEG gels and has shown to induce early stages of chondrogenesis, while its persistence can limit complete differentiation. Therefore, an MMP-13 cleavage site was incorporated into the peptide sequence to release RGD mimicking the native differentiation timeline. Active MMP-13 production of encapsulated hMSCs was seen to increase from day 9 to 14 and only in chondrogenic differentiating cultures. Seeded hMSCs attached to the material prior to enzymatic cleavage, but a significant population of the cells detach after cleavage and release of RGD. Finally, hMSCs encapsulated in RGD-releasing gels produce 10 times as much glycosaminoglycan as cells with uncleavable RGD functionalities, by day 21 of culture. Furthermore, 75% of the cells stain positive for collagen type II deposition where RGD is cleavable, as compared to 19% for cultures where RGD persists. Collectively, these data provide evidence that temporal regulation of integrin-binding peptides is important in the design of niches in differentiating hMSCs to chondrocytes.

Nucleolin binds specifically to an AP-1 DNA sequence and represses AP1-dependent transactivation of the matrix metalloproteinase-13 gene

Transcriptional regulation via activator protein-1 (AP-1) protein binding to AP-1 binding sites within gene promoter regions of AP-1 target genes plays a key role in controlling cellular invasion, proliferation, and oncogenesis, and is important to pathogenesis of arthritis and cardiovascular disease. To identify new proteins that interact with the AP-1 DNA binding site, we performed the DNA affinity chromatography-based Nucleotide Affinity Preincubation Specificity TEst of Recognition (NAPSTER) assay, and discovered a 97 kDa protein that binds in vitro to a minimal AP-1 DNA sequence element. Mass spectrometric fragmentation sequencing determined that p97 is nucleolin. Immunoblotting of DNA affinity-purified material with anti-nucleolin antibodies confirmed this identification. Nucleolin also binds the AP-1 site in gel shift assays. Nucleolin interacts in NAPSTER with the AP-1 site within the promoter sequence of the metalloproteinase-13 gene (MMP-13), and binds in vivo in chromatin immunoprecipitation assays in the vicinity of the AP-1 site in the MMP-13 promoter. Overexpression of nucleolin in human HeLa cervical carcinoma cells significantly represses AP-1 dependent gene transactivation of a minimal AP-1 reporter construct and of an MMP-13 promoter reporter sequence. This is the first report of nucleolin binding and transregulation at the AP-1 site.

Altered gene expression levels of matrix metalloproteinases and their inhibitors in periodontitis-affected gingival tissue

BACKGROUND

The balance between the degradation and synthesis of extracellular matrix determines periodontal attachment levels and alveolar bone matrix concentration in periodontal diseases. Matrix metalloproteinases (MMPs) are known to degrade periodontal ligamental attachment and bone matrix proteins. The purpose of this study was to examine the effect of different expression levels of MMPs and their inhibitors, the tissue inhibitors of matrix metalloproteinases (TIMPs), in periodontitis.

METHODS

Sixteen inflamed gingival tissue samples from subjects with generalized chronic periodontitis and 14 control tissue samples from systemically and periodontally healthy subjects were evaluated. The total RNA was extracted, and the transcript levels for MMP-1, -3, -9, and -13 and TIMP-1, -2, -3, and -4 relative to beta-actin were determined by quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

Gene transcript levels for MMP-1 and TIMP-4 were significantly higher in periodontitis-affected gingival tissues (P <0.05). MMP-3, -9, and -13 and TIMP-1 mRNAs also were elevated in periodontitis; however, the difference was not statistically significant. TIMP-2 and -3 mRNA levels were similar in healthy and diseased gingivae. The ratios of MMP-1/TIMP-2 (P <0.01), MMP-3/TIMP-2 (P <0.05), MMP-9/TIMP-2 (P <0.05), and MMP-1/TIMP-3 (P <0.01) from periodontitis lesions were significantly higher than those in the control tissues.

CONCLUSIONS

Upregulated MMP expression and an increased MMP/TIMP ratio indicate that a potential imbalance between degradation and synthesis of extracellular matrix persists in periodontitis-affected gingival tissues. This process may be responsible for increased tissue breakdown in periodontitis.

Mechanism of glycosaminoglycan-mediated bone and joint disease: implications for the mucopolysaccharidoses and other connective tissue diseases

We have previously shown that glycosaminoglycan (GAG) storage in animal models of the mucopolysaccharidoses (MPS) leads to inflammation and apoptosis within cartilage. We have now extended these findings to synovial tissue and further explored the mechanism underlying GAG-mediated disease. Analysis of MPS rats, cats, and/or dogs revealed that MPS synovial fibroblasts and fluid displayed elevated expression of numerous inflammatory molecules, including several proteins important for lipopolysaccharide signaling (eg, Toll-like receptor 4 and lipoprotein-binding protein). The expression of tumor necrosis factor, in particular, was elevated up to 50-fold, leading to up-regulation of the osteoclast survival factor, receptor activator of nuclear factor-kappaB ligand, and the appearance of multinucleated osteoclast-like cells in the MPS bone marrow. Treatment of normal synovial fibroblasts with GAGs also led to production of the prosurvival lipid sphingosine-1-phosphate, resulting in enhanced cell proliferation, consistent with the hyperplastic synovial tissue observed in MPS patients. In contrast, GAG treatment of normal chondrocytes led to production of the proapoptotic lipid ceramide, confirming the enhanced cell death we had previously observed in MPS cartilage. These findings have important implications for the pathogenesis and treatment of MPS and have further defined the mechanism of GAG-stimulated disease.

Identification of potent and selective MMP-13 inhibitors

A potent, selective series of MMP-13 inhibitors has been derived from a weak (3.2 microM) inhibitor that did not bear a zinc chelator. Structure-based drug design strategies were employed to append a Zn-chelating group to one end of the molecule and functionality to enhance selectivity to the other. A compound from this series demonstrated rat oral bioavailability and efficacy in a bovine articular cartilage explant model.