The activity of collagenase-1 is required for keratinocyte migration on a type I collagen matrix

Dynamic reciprocity in the wound microenvironment

Here, we define dynamic reciprocity (DR) as an ongoing, bidirectional interaction among cells and their surrounding microenvironment. In this review, we posit that DR is especially meaningful during wound healing as the DR-driven biochemical, biophysical, and cellular responses to injury play pivotal roles in regulating tissue regenerative responses. Such cell-extracellular matrix interactions not only guide and regulate cellular morphology, but also cellular differentiation, migration, proliferation, and survival during tissue development, including, e.g., embryogenesis, angiogenesis, as well as during pathologic processes including cancer, diabetes, hypertension, and chronic wound healing. Herein, we examine DR within the wound microenvironment while considering specific examples across acute and chronic wound healing. This review also considers how a number of hypotheses that attempt to explain chronic wound pathophysiology may be understood within the DR framework. The implications of applying the principles of DR to optimize wound care practice and future development of innovative wound healing therapeutics are also briefly considered.

Gene profiling of the rat medial collateral ligament during early healing using microarray analysis

Ligament heals in a synchronized and complex series of events. The remodeling process may last months or years. Experimental evidence suggests the damaged ligament does not recover its normal functional properties. Specific mechanisms to prevent scar formation and to regenerate the original mechanical function remain elusive but likely involve regulation of creeping substitution. Creeping substitution creates a larger hypercellular, hypervascular, and disorganized granulation tissue mass that results in an inefficient and nonregenerative wound healing process for the ligament. Control of creeping substitution may limit the extent of this tissue compromise and reduce the time necessary for healing. The objective of this study is to better understand the mechanism behind scar formation by identifying the extracellular matrix factors and other unique genes of interest differentially expressed during rat ligament healing via microarray. For this study, rat medial collateral ligaments were either surgically transected or left intact. Ligaments were collected at day 3 or 7 postinjury and used for microarray, quantitative PCR, and/or immunohistochemistry. Results were compared with the normal intact ligament. We demonstrate that early ligament healing is characterized by the modulation of several inflammatory and extracellular matrix factors during the first week of injury. Specifically, a number of matrix metalloproteinases and collagens are differentially and significantly expressed during early ligament healing. Additionally, we demonstrate the modulation of three novel genes, periostin, collagen-triple helix repeat containing-1, and serine protease 35 in our ligament healing model. Together, control of granulation tissue creeping substitution and subsequent downstream scar formation is likely to involve these factors.

Does inflammation have a role in the pathogenesis of venous ulcers? A critical review of the evidence

Chronic venous disease, a disorder involving venous return from the legs, is a growing epidemic in the developed world. Numerous studies have been conducted in the past two decades in an attempt to elucidate its underlying pathophysiology. Many theories have been proposed to address the profound inflammatory dysregulation, with the majority focusing on fibrin trap, inflammatory trap, cytokines, growth factors, and matrix metalloproteinases. Although many of these theories have obtained great momentum, much of the data are contradictory. Moreover, many treatments built on these theories have claimed overwhelming success despite insufficient evidence. At the same time, there are few reviews that critically analyze and evaluate these data. Therefore, in this paper, we will provide summaries of the background data and evolution of these theories and examine their supporting evidence.

Localizing matrix metalloproteinase activities in the pericellular environment

Matrix metalloproteinases (MMPs) are a group of structurally related proteolytic enzymes containing a zinc ion in the active site. They are secreted from cells or bound to the plasma membrane and hydrolyze extracellular matrix (ECM) and cell surface-bound molecules. They therefore play key roles in morphogenesis, wound healing, tissue repair and remodeling in diseases such as cancer and arthritis. Although the cell anchored membrane-type MMPs (MT-MMPs) function pericellularly, the secreted MMPs have been considered to act within the ECM, away from the cells from which they are synthesized. However, recent studies have shown that secreted MMPs bind to specific cell surface receptors, membrane-anchored proteins or cell-associated ECM molecules and function pericellularly at focussed locations. This minireview describes examples of cell surface and pericellular partners of MMPs, as well as how they alter enzyme function and cellular behaviour.

Differentiation status of limbal epithelial cells cultured on intact and denuded amniotic membrane before and after air-lifting

We have investigated differences in bovine limbal epithelial cell differentiation when expanded upon intact (amniotic epithelial cells and basement membrane remaining) and denuded human amniotic membrane (AM), a commonly used substrate in ophthalmic surgery for corneal stem cell transplantation. Ex vivo expansion of the epithelial cells, in supplemented media, continued for 2 weeks followed by 1 week under air-lifting conditions. Before and after air-lifting the differentiated (K3/K12 positive) and undifferentiated (K14 positive) cells were quantified by immunohistochemistry, Western blotting, and quantitative polymerase chain reaction. Limbal epithelial cells expanded upon AM formed 4-6 stratified layers, both on intact AM (iAM) and denuded AM (dAM). On dAM the proportion of differentiated cells remained unaltered after air-lifting. Within cells grown on iAM, however, the number of differentiated cells increased significantly after air-lifting. These results have important implications for both basic and clinical research. First, they show that bovine limbal epithelia can be used as an alternative source of cells for basic research investigating ex vivo limbal stem cells expansion. Second, these findings serve as a warning to clinicians that the effect of AM on transplantable cells is not fully understood; the use of iAM or dAM can produce different results in terms of the amount of differentiation, once cells are exposed to the air.

Epidermal growth factor (EGF) induces motility and upregulates MMP-9 and TIMP-1 in bovine trophoblast cells

Differentiation and restricted invasion/migration of trophoblast cells are crucial for feto-maternal communication in the synepitheliochorial placenta of cattle. EGF is expressed in the bovine placenta and likely regulates these cell properties. As cell migration and motility rely on the degradation of extracellular matrix we hypothesize that EGF is involved in the regulation of the MMP-9/TIMP-1 balance and thus could influence trophoblast migration, tissue remodeling, and the release of the fetal membranes after parturition. The aim of this in vitro study was to examine EGF-mediated effects on cell motility, proliferation, and MMP-9 and TIMP-1 expression in cultured bovine trophoblast cells. We used a trophoblast cell line (F3) derived from bovine placentomes to examine the influence of EGF on MMP-9 and TIMP-1 expression by semiquantitative RT-PCR and MMP activity by zymography. Migration assays were performed using a Boyden chamber and cell motility was measured by time-lapse analyses. To identify the involved signaling cascades, phosphorylation of mitogen-activated protein kinase (MAPK) 42/44 and Akt was detected by Western blot. EGF treatment increased both the abundance of MMP-9 and TIMP-1 mRNAs and the proteolytic activity of MMP-9. Furthermore, EGF stimulated proliferation and migration of F3 cells. Addition of specific inhibitors of MAPK (PD98059) and/or PI3K (LY294002) activation abolished or reduced EGF-induced effects in all experiments. In conclusion, EGF-mediated effects stimulate migration and proliferation of bovine trophoblast cells and may be involved in bovine placental tissue remodeling and postpartum release of fetal membranes.

2-(3-Methoxyphenyl)-6, 7-methylenedioxoquinolin-4-one, a novel synthetic compound, inhibited migration and invasion in TSGH8301 human bladder cancer cells

Matrix metalloproteinases (MMPs) play an important role in the invasion, metastasis and angiogenesis of cancer cells. Many agents have been shown to inhibit the cancer cell migration and invasion by suppression of MMPs. 2-(3-Methoxyphenyl)-6,7-methylenedioxoquinolin-4-one (MMEQ) is a derivative compound synthesized from quinolin and the purpose of this study is to determine whether or not cell migration would be reduced in human bladder cancer TSGH8301 cells after MMEQ treatment. Wound healing assay and boyden chamber assay were used in cell migration and invasion determinations. Cell migration and invasion inhibited by MMEQ exerted an inhibitory effect on the sevenless homolog-1 (SOS-1), protein kinase c (PKC), extracellular signal-regulated kinase (ERK) and Rho A for causing the inhibitions of MMP-2 and -9, and then followed by the inhibitions of invasion and migration. MMEQ also affected FAK, PI3K or inhibited growth factor receptor-bound protein 2 (GRB2), nuclear factor kappaB (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) for cell proliferation inhibition. Therefore, MMEQ may serve as a drug in the prevention of tumor metastasis of bladder cancer in the future.

Degradation of human collagen isoforms by Clostridium collagenase and the effects of degradation products on cell migration

Clostridium collagenase has been widely used in biomedical research to dissociate tissues and isolate cells; and, since 1965, as a therapeutic drug for the removal of necrotic wound tissues. Previous studies found that purified collagenase-treated extracellular matrix stimulated cellular response to injury and increased cell proliferation and migration. This article presents an in vitro study investigating the digestive ability of Clostridium collagenase on human collagen types I, III, IV, V and VI. Our results showed that Clostridium collagenase displays proteolytic power to digest all these types of human collagen, except type VI. The degradation products derived were tested in cell migration assays using human keratinocytes (gold surface migration assay) and fibroblasts (chemotaxis cell migration assay). Clostridium collagenase itself and the degradation products of type I and III collagens showed an increase in keratinocyte and fibroblast migration, type IV-induced fibroblast migration only, and the remainder showed no effects compared with the control. The data indicate that Clostridium collagenase can effectively digest collagen isoforms that are present in necrotic wound tissues and suggest that collagenase treatment provides several mechanisms to enhance cell migration: collagenase itself and collagen degradation products.

Dynamic interplay between the collagen scaffold and tumor evolution

The extracellular matrix (ECM) is a key regulator of cell and tissue function. Traditionally, the ECM has been thought of primarily as a physical scaffold that binds cells and tissues together. However, the ECM also elicits biochemical and biophysical signaling. Controlled proteolysis and remodeling of the ECM network regulate tissue tension, generate pathways for migration, and release ECM protein fragments to direct normal developmental processes such as branching morphogenesis. Collagens are major components of the ECM of which basement membrane type IV and interstitial matrix type I are the most prevalent. Here we discuss how abnormal expression, proteolysis and structure of these collagens influence cellular functions to elicit multiple effects on tumors, including proliferation, initiation, invasion, metastasis, and therapy response.

14-3-3 sigma associates with cell surface aminopeptidase N in the regulation of matrix metalloproteinase-1

Matrix metalloproteinases (MMPs) are implicated in the degradation of the extracellular matrix during development and tissue repair, as well as in pathological conditions such as tumor invasion and fibrosis. MMP expression by stromal cells is partly regulated by signals from the neighboring epithelial cells. Keratinocyte-releasable 14-3-3sigma, or stratifin, acts as a potent MMP-1-stimulatory factor in fibroblasts. However, its mechanism of transmembrane signaling remains unknown. Ectodomain biotin labeling, serial affinity purification and mass spectroscopy analysis revealed that the stratifin associates with aminopeptidase N (APN), or CD13, at the cell surface. The transient knockdown of APN in fibroblasts eliminated the stratifin-mediated p38 MAP kinase activation and MMP-1 expression, implicating APN in a receptor-mediated transmembrane signaling event. Stratifin deletion studies implicated its C-terminus as a potential APN-binding site. Furthermore, the dephosphorylation of APN ectodomains reduced its binding affinity to the stratifin. The presence of a phosphorylated serine or threonine residue in APN has been implicated. Together, these findings provide evidence that APN is a novel cell surface receptor for stratifin and a potential target in the regulation of MMP-1 expression in epithelial-stromal cell communication.

Skin wound healing modulation by macrophages

Skin wound healing is a multi stage phenomenon that requires the activation, recruitment or activity of numerous cell types as keratinocytes, endothelial cells, fibroblast and inflammatory cells. Among the latter, macrophages appear to be central to this process. They colonize the wound at its very early stage and in addition to their protective immune role seem to organize the activity of other cell types at the following stages of the healing. Their benefit to this process is however controversial, as macrophages are described to promote the speed of healing but may also favour the fibrosis resulting from it in scars. Moreover wound healing defects are associated with abnormalities in the inflammatory phase. In this review, we summarise our knowledge on what are the Wound Associated Macrophages, and how they interact with the other cell types to control the reepithelisation, angiogenesis and the extracellular matrix remodelling. We believe this knowledge may open new avenues for therapeutic intervention on skin wounds.

Current concepts in the pathogenesis of psoriasis

Psoriasis is a multi-factorial skin disease with a complex pathogenesis. Various factors which have been suggested to play a key role in the pathogenesis are T cells, antigen presenting cells (APC's), keratinocytes, Langerhans' cells, macrophages, natural killer cells, an array of Th1 type cytokines, certain growth factors like vascular endothelial growth factor (VEGF), keratinocyte growth factor (KGF), and others. It has been hypothesized that the disease starts with the activation of T cell by an unknown antigen, which leads to secretion of an array of cytokines by activated T cells, inflammatory cells, and keratinocytes. The characteristic lesion of psoriasis is due to the hyper-proliferation of the keratinocyte. Activated Langerhans' cells migrate from skin to lymph nodes presenting the antigen to nodal naïve T cells (cells that have not been activated by antigen previously). The T cells activated by non-antigen-dependent mechanism may, however, become antigen-specific memory cells that react with a cross-reactive auto-antigen such as keratin (molecular mimicry). The genetic background of the disease may be suggested from the fact that concordance rate is 63–73% in monozygotic twins, as compared to 17–20% in dizygotic twins. Several disease susceptibility loci have been suggested as predisposing factors, PSORS1-PSORS9.

Molecular mediators of angiogenesis

Angiogenesis, or the formation of new blood vessels from the preexisting vasculature, is a key component in numerous physiologic and pathologic responses and has broad impact in many medical and surgical specialties. In this review, we discuss the key cellular steps that lead to the neovascularization of tissues and highlight the main molecular mechanisms and mediators in this process. We include discussions on proteolytic enzymes, cell-matrix interactions, and pertinent cell signaling pathways and end with a survey of the mechanisms that lead to the stabilization and maturation of neovasculatures.

Role of matrix metalloproteinases in epithelial migration

In response to injury, epithelial cells migrate across the denuded tissue to rapidly close the wound and restore barrier, thereby preventing the entry of pathogens and leakage of fluids. Efficient, proper migration requires a range of processes, acting both inside and out of the cell. Among the extracellular responses is the expression of various matrix metalloproteinases (MMPs). Though long thought to ease cell migration simply by breaking down matrix barriers, findings from various models demonstrate that MMPs facilitate (and sometimes repress) cell movement by other means, such as affecting the state of cell-matrix interactions or proliferation. In this Prospect, we review some key data indicting how specific MMPs function via their activity as proteinases to control closure of epithelial wounds.

Benzyl isothiocyanate (BITC) inhibits migration and invasion of human colon cancer HT29 cells by inhibiting matrix metalloproteinase-2/-9 and urokinase plasminogen (uPA) through PKC and MAPK signaling pathway

Benzyl isothiocyanate (BITC), a component of dietary cruciferous vegetables, has antioxidant and anticancer properties. In this study, we show for the first time the antimetastatic effects of BITC in human colon cancer HT29 cells. BITC had an inhibitory effect on cell migration and invasion. Protein levels of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and urokinase-plasminogen activator (u-PA) were reduced by BITC in a concentration-dependent manner. BITC also exerted an inhibitory effect on phosphorylation of c-Jun N-terminal kinase 1 and 2 (JNK1/2), extracellular signal-regulated kinases 1 and 2 (ERK1/2), phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) that are upstream of nuclear factor kappa B (NF-kappaB). BITC inhibited DNA binding activity of NF-kappaB. Moreover, BITC decreased the levels of c-Fos, c-Jun, Ras, FAK, PI3K and GRB2 in HT29 cells. Reductions in the enzyme activity, protein and mRNA (mRNA) levels of MMP-2 were observed in BITC-treated HT29 cells. BITC also inhibited mRNA levels of MMP-2, -7, and -9 in HT29 cells. Results from zymography showed that BITC treatment decreased MMP-2 expression in a concentration-dependent manner. BITC inhibited PKCdelta activity in HT29 cells. Furthermore, inhibitors specific for JNK (SP600125) reduced expression of MMP-2, MMP-9, and u-PA. These results demonstrated that BITC could alter HT29 cell metastasis by reduction of MMP-2, MMP-9, and u-PA expression through the suppression of a PKC, MAPK signaling pathway and inhibition of NF-kappaB levels. These findings suggest that BITC has potential as an antimetastatic agent.

Epidermal growth factor in clinical practice - a review of its biological actions, clinical indications and safety implications

Chemotaxis, mitogenesis, motogenesis and cytoprotection are common cellular events involved in both tumourigenesis and tissue repair, which appear amplified upon growth factors exposure. Epidermal growth factor (EGF) promotes these events in epithelial and mesenchymal cells through the binding to a specific tyrosine kinase receptor. In experimental oncology settings, EGF does not initiate malignant transformation but exhibits 'tumour promotion'. These observations have raised doubts on the clinical use of EGF despite solid demonstrations of efficacy in experimental conditions and clinical trials. The results of a Pubmed and Bioline investigation on EGF clinical uses and preclinical safety data are presented here. EGF topical administration has been used since 1989 to enhance the healing process of a variety of peripheral tissues wounds (16 clinical reports), as well as its intravenous, oral and rectal administration for gastrointestinal damages (11 clinical reports). EGF therapeutic efficacy and excellent tolerability seem demonstrated. Lack of long-term adverse effects is highlighted in those studies with 6, 12 and 24 months of patients follow-up. Although post-treatment follow-up may fall short for malignant growth, there are no reports on evidences linking EGF clinical use with cancer. A multicentre, nationwide survey in Cuba, 15 years after randomly using silver sulphadiazine with EGF or not in burn victims yielded that cancer incidence was comparable between EGF-treated and control subjects and that such incidence rate does not differ from the age-matched national incidence for those 15-year period. All the animal species subjected to long-term EGF systemic administration exhibit dose-dependent and reversible epithelial organs hyperplasia with no changes in cells phenotypic differentiation. Histotypic pre-malignant markers were not identified. The results emerged from co-carcinogenesis studies and from transgenic mice over-expressing EGF are conflicting and indicate that EGF overexposure, either innate or postnatal, may not be sufficient to transform cells. The ability of EGF to heal injured tissues in life-threatening scenarios or to assist in preventing physical and social disability advocates for its clinical use under a rational medical risk/benefit balance.

MMP-12 catalytic domain recognizes and cleaves at multiple sites in human skin collagen type I and type III

Collagens of either soft connective or mineralized tissues are subject to continuous remodeling and turnover. Undesired cleavage can be the result of an imbalance between proteases and their inhibitors. Owing to their superhelical structure, collagens are resistant to many proteases and matrix metalloproteinases (MMPs) are required to initiate further degradation by other enzymes. Several MMPs are known to degrade collagens, but the action of MMP-12 has not yet been studied in detail. In this work, the potential of MMP-12 in recognizing sites in human skin collagen types I and III has been investigated. The catalytic domain of MMP-12 binds to the triple helix and cleaves the typical sites -Gly(775)-Leu(776)- in alpha-2 type I collagen and -Gly(775)-Ile(776)- in alpha-1 type I and type III collagens and at multiple other sites in both collagen types. Moreover, it was observed that the region around these typical sites contains comparatively less prolines, of which some have been proven to be only partially hydroxylated. This is of relevance since partial hydroxylation in the vicinity of a potential scissile bond may have a local effect on the conformational thermodynamics with probable consequences on the collagenolysis process. Taken together, the results of the present work confirm that the catalytic domain of MMP-12 alone binds and degrades collagens I and III.

MMP7 shedding of syndecan-1 facilitates re-epithelialization by affecting alpha(2)beta(1) integrin activation

Background

Lung injury promotes the expression of matrix metalloproteinase-7 (MMP7, matrilysin), which is required for neutrophil recruitment and re-epithelialization. MMP7 governs the lung inflammatory response through the shedding of syndecan-1. Because inflammation and repair are related events, we evaluated the role of syndecan-1 shedding in lung re-epithelialization.

Methodology/Principal Finding

Epithelial injury induced syndecan-1 shedding from wild-type epithelium but not from Mmp7^−/− mice in vitro and in vivo. Moreover, cell migration and wound closure was enhanced by MMP7 shedding of syndecan-1. Additionally, we found that syndecan-1 augmented cell adhesion to collagen by controlling the affinity state of the α₂β₁ integrin.

Conclusion/Significance

MMP7 shedding of syndecan-1 facilitates wound closure by causing the α₂β₁ integrin to assume a less active conformation thereby removing restrictions to migration. MMP7 acts in the lungs to regulate inflammation and repair, and our data now show that both these functions are controlled through the shedding of syndecan-1.

Cytosolic SYT/SS18 isoforms are actin-associated proteins that function in matrix-specific adhesion

SYT (SYnovial sarcoma Translocated gene or SS18) is widely produced as two isoforms, SYT/L and SYT/S, that are thought to function in the nucleus as transcriptional coactivators. Using isoform-specific antibodies, we detected a sizable pool of SYT isoforms in the cytosol where the proteins were organized into filamentous arrays. Actin and actin-associated proteins co-immunoprecipitated with SYT isoforms, which also co-sedimented and co-localized with the actin cytoskeleton in cultured cells and tissues. The association of SYT with actin bundles was extensive yet stopped short of the distal ends at focal adhesions. Disruption of the actin cytoskeleton also led to a breakdown of the filamentous organization of SYT isoforms in the cytosol. RNAi ablation of SYT/L alone or both isoforms markedly impaired formation of stress fibers and focal adhesions but did not affect formation of cortical actin bundles. Furthermore, ablation of SYT led to markedly impaired adhesion and spreading on fibronectin and laminin-111 but not on collagen types I or IV. These findings indicate that cytoplasmic SYT isoforms interact with actin filaments and function in the ability cells to bind and react to specific extracellular matrices.

Alpha3beta1 integrin in epidermis promotes wound angiogenesis and keratinocyte-to-endothelial-cell crosstalk through the induction of MRP3

During cutaneous wound healing, epidermal keratinocytes play essential roles in the secretion of factors that promote angiogenesis. However, specific cues in the wound microenvironment that trigger the production of pro-angiogenic factors by keratinocytes, and the cellular receptors that mediate this response, remain unclear. In this study, we exploited a model of conditional integrin knockout to demonstrate impaired wound angiogenesis in mice that lack alpha3beta1 integrin in epidermis. In addition, we used genetic and shRNA approaches to determine that alpha3beta1-integrin deficiency in keratinocytes leads to reduced mRNA and protein expression of the pro-angiogenic factor mitogen-regulated protein 3 (MRP3; also known as PRL2C4), and to demonstrate that this regulation provides a mechanism of keratinocyte-to-endothelial-cell crosstalk that promotes endothelial-cell migration. Finally, we showed that the impaired wound angiogenesis in epidermis-specific alpha3-integrin-knockout mice is correlated with reduced expression of MRP3 in wounded epidermis. These findings identify a novel role for alpha3beta1 integrin in promoting wound angiogenesis through a mechanism of crosstalk from epidermal to endothelial cells, and they implicate MRP3 in this integrin-dependent crosstalk. Such a mechanism represents a novel paradigm for integrin-mediated regulation of wound angiogenesis that extends beyond traditional roles for integrins in cell adhesion and migration.

A combination of curcumin and ginger extract improves abrasion wound healing in corticosteroid-impaired hairless rat skin

Hairless rats were topically treated with a combination of 10% curcumin and 3% ginger extract (or with each agent alone) for a 21-day period. Following this, the rats were treated topically with Temovate (corticosteroid) for an additional 15 days. At the end of the treatment period, superficial abrasion wounds were induced in the treated skin. Abrasion wounds healed more slowly in the skin of Temovate-treated rats than in skin of control animals. Healing was more rapid in skin of rats that had been pretreated with either curcumin or ginger extract alone or with the combination of curcumin-ginger extract (along with Temovate) than in the skin of rats treated with Temovate and vehicle alone. Skin samples were obtained at the time of wound closure. Collagen production was increased and matrix metalloproteinase-9 production was decreased in the recently healed skin from rats treated with the botanical preparation relative to rats treated with Temovate plus vehicle. In none of the rats was there any indication of skin irritation during the treatment phase or during wounding and repair. Taken together, these data suggest that a combination of curcumin and ginger extract might provide a novel approach to improving structure and function in skin and, concomitantly, reducing formation of nonhealing wounds in "at-risk" skin.

Matrix metalloproteinase-1 cleavage site recognition and binding in full-length human type III collagen

Matrix metalloproteinases (MMPs) are essential for normal collagen turnover, recovery from fibrosis, and vascular permeability. In fibrillar collagens, MMP-1, MMP-8, and MMP-13 cleave a specific glycine-isoleucine or glycine-leucine bond, despite the presence of this sequence in other parts of the protein. This cut site specificity has been hypothesized to arise from a unique, relaxed super-secondary structure in this area due to local hydroxyproline poor character. In this study we examined the mechanism of interaction and cleavage of human type III collagen by fibroblast MMP-1 by using a panel of recombinant human type III collagens (rhCIIIs) containing engineered sequences in the vicinity of the cleavage site. Native and recombinant type III collagens had similar biochemical and structural characteristics, as indicated by transmission electron microscopy, circular dichroism spectropolarimetry, melting temperature and hydroxyproline analysis. A single amino acid change at the I785 cleavage site to proline resulted in partial MMP-1 resistance, but cuts were found in novel sites in the original cleavage region. However, the replacement of five Y-position residues by proline in this region, regardless of I785 variation, conferred complete resistance to MMP-1, MMP-8, MMP-13, trypsin, and elastase. MMP-1 had a decreased specific activity towards and reduced cleavage rate of rhCIII I785P but a K(m) similar to wild-type. Despite the reductions in protease sensitivity, MMP-1 bound to all of the engineered rhCIIIs with comparable affinity, indicating that MMP-1 binding is not sufficient for cleavage. The relaxed tertiary structure in the MMP cleavage region may permit local collagen unwinding by MMP-1 that enables site-specific proteolysis.

Impaired keratinocyte function on matrix metalloproteinase-1 (MMP-1) damaged collagen

Healing of superficial skin wounds depends on the proliferation and migration of keratinocytes at the wound margin. When human epidermal keratinocytes were incubated on polymerized type I collagen, they rapidly attached and spread. The cells underwent a proliferative response and, over the subsequent 6-day period, covered the collagen surface with a monolayer of cells. When keratinocytes were plated on collagen that had been fragmented by exposure to matrix metalloproteinase-1 (MMP-1, collagenase-1), the cells attached as readily as to intact collagen but spread more slowly and less completely. Growth was reduced by approximately 50%. Instead of covering the collagen surface, the keratinocytes remained localized to the site of attachment. Keratinocytes on fragmented collagen expressed a more differentiated phenotype as indicated by a higher level of surface E-cadherin. Based on these findings, we suggest that damage to the underlying collagenous matrix may impede efficient keratinocyte function and retard wound closure.

Epidermal growth factor receptor/beta-catenin/T-cell factor 4/matrix metalloproteinase 1: a new pathway for regulating keratinocyte invasiveness after UVA irradiation

Previous studies have established that UV irradiation results in epidermal growth factor receptor (EGFR) activation in keratinocytes. However, the signaling pathways and cellular effects related to this process remain incompletely elucidated. Herein, we describe for the first time that UVA-mediated EGFR activation results in beta-catenin tyrosine phosphorylation at the Y654 residue responsible for the dissociation of E-cadherin/alpha-catenin/beta-catenin complexes. Moreover, UVA induces an EGFR-dependent, but Wnt-independent, beta-catenin relocalization from the membrane to the nucleus followed by its association with T-cell factor 4 (TCF4). This newly formed beta-catenin/TCF4 complex binds to a specific site on matrix metalloproteinase 1 (MMP1) promoter and governs MMP1 gene and protein expression, as well as cell migration in collagen and gelatin. Altogether, these results suggest that UVA stimulates keratinocyte invasiveness through two coordinated EGFR-dependent processes: loss of cell-to-cell contact due to beta-catenin/E-cadherin/alpha-catenin dissociation and increased cell migration through extracellular matrix component degradation due to beta-catenin/TCF4-dependent MMP1 regulation. These events may represent an important step in epidermis repair following UVA injury and their abnormal regulation could contribute to photoaging and photocarcinogenesis.

Expression of CCN family of genes in human skin in vivo and alterations by solar-simulated ultraviolet irradiation

The CCN family of proteins is involved in diverse biological functions such as cell growth, adhesion, migration, angiogenesis, and regulation of extracellular matrix. We have investigated expression of CCN family genes and alternations induced by solar-simulated ultraviolet irradiation in human skin in vivo. Transcripts of all six CCN genes were expressed in human skin in vivo. CCN5 was most abundantly expressed followed by CCN2>CCN3>CCN1>CCN4>CCN6. Solar-simulated ultraviolet irradiation increased mRNA expression of CCN1 and CCN2. In contrast, mRNA levels of CCN3, CCN4, CCN5, and CCN6, were reduced. Knowledge gained from this study provides the foundation to explore the functional roles of CCN gene products in cutaneous biology and responses to solar ultraviolet irradiation.

Involvement of matrix metalloproteinases on the inhibition of cells invasion and migration by emodin in human neuroblastoma SH-SY5Y cells

Emodin (1,3,8-trihydroxy-6-methylanthaquinone), an active component present in the root and rhizome of Rheum palmatum L. (Polygonaceae) has anti-bacterial, anti-tumor, diuretic and vasorelaxant effects. However, its mechanism of action on the cell migration and invasion of human neuroblastoma cancer SH-SY5Y cells is not fully understood. In this study, firstly, the effects of emodin on the percentage of viable cells were examined by using MTT assay and it was found that emodin induced dose-and time-dependent inhibition in human neuroblastoma SH-SY5Y cells. Second, the effects of emodin on the migration and invasion of SH-SY5Y cells were examined by using wound assay and matrigel counting and the results showed that emodin suppressed the migration and invasion of SH-SY5Y cells. Third, we examined the effect of emodin on the levels of associated proteins by using Western blotting and the results indicated that emodin inhibited the levels of GRB2, RhoA, HIF-1alpha, VEGF, FAK, iNOS, COX2, p-p38, p-c-jun, MMP2, MMP9 and MMP7 but promoted the levels of PKC, PI3K, MEKK3 and NF-kappaB p65 that led to the inhibition of migration and invasion of SH-SY5Y cells in vitro.

Extracellular matrix-induced gene expression in human breast cancer cells

Extracellular matrix (ECM) molecules modify gene expression through attachment-dependent (focal adhesion-related) integrin receptor signaling. It was previously unknown whether the same molecules acting as soluble peptides could generate signal cascades without the associated mechanical anchoring, a condition that may be encountered during matrix remodeling and degradation and relevant to invasion and metastatic processes. In the current study, the role of ECM ligand-regulated gene expression through this attachment-independent process was examined. It was observed that fibronectin, laminin, and collagen type I and II induce Smad2 activation in MCF-10A and MCF-7 cells. This activation is not caused by transforming growth factor (TGF)-beta ligand contamination or autocrine TGF involvement and is 3- to 5-fold less robust than the TGF-beta1 ligand. The resulting nuclear translocation of Smad4 in response to ECM ligand indicates downstream transcriptional responses occurring. Coimmunoprecipitation experiments determined that collagen type II and laminin act through interaction with integrin alpha(2)beta(1) receptor complex. The ECM ligand-induced Smad activation (termed signaling crosstalk) resulted in cell type and ligand-specific transcriptional changes, which are distinct from the TGF-beta ligand-induced responses. These findings show that cell-matrix communication is more complex than previously thought. Soluble ECM peptides drive transcriptional regulation through corresponding adhesion and non-attachment-related processes. The resultant gene expressional patterns correlate with pathway activity and not by the extent of Smad activation. These results extend the complexity and the existing paradigms of ECM-cell communication to ECM ligand regulation without the necessity of mechanical coupling.

Hyperglycaemic conditions hamper keratinocyte locomotion via sequential inhibition of distinct pathways: new insights on poor wound closure in patients with diabetes

BACKGROUND

Diabetes mellitus (DM) is characterized by impaired insulin signalling, elevated plasma glucose, and predisposition towards complications involving several organs. A major complication of DM is impairment of wound healing. In the re-epithelialization process during wound healing, migration of keratinocytes is a crucial step. Our previous report demonstrated that keratinocytes cultured in hyperglycaemic media showed decreased cell mobility.

OBJECTIVES

The current study aimed to explore the effects of high glucose on keratinocyte migration after different treatment durations.

METHODS

Keratinocytes were cultivated for indicated time periods under various concentrations of glucose. Relevant assays including Transwell migration and in vitro wound scratch assays, flow cytometric analysis, matrix metalloproteinase-1 (MMP-1) activity assay, determination of mRNA expression and Western blotting were performed.

RESULTS

We demonstrated that (i) keratinocyte motility progressively and significantly decreased; (ii) the keratinocyte activation marker K16 was significantly suppressed; (iii) expression of alpha2beta1 integrin and MMP-1, both crucial for keratinocyte locomotion on collagen type I, was significantly downregulated; and (iv) expression of the phosphorylated signal transducer and activator of transcription-1 significantly decreased after hyperglycaemic treatment. More specifically, different pathways become involved after prolonged duration of high glucose cultivation to reduce keratinocyte locomotion further.

CONCLUSIONS

We have demonstrated that high glucose treatment results in progressive suppression of keratinocyte locomotion and elucidated the molecular mechanisms involved. These results provide a reasonable explanation for the poor wound healing seen in patients with DM.

Mice that lack matrix metalloproteinase-9 display delayed wound healing associated with delayed reepithelization and disordered collagen fibrillogenesis

Matrix metalloproteinase- (MMP-9) is involved in processes that occur during cutaneous wound healing such as inflammation, matrix remodeling, and epithelialization, To investigate its role in healing, full thickness skin wounds were made in the dorsal region of MMP-9-null and control mice and harvested up to 14 days post wounding. Gross examination and histological and immunohistochemical analysis indicated delayed healing in MMP-9-null mice. Specifically, MMP-9-null wounds displayed compromised reepithelialization and reduced clearance of fibrin clots. In addition, they exhibited abnormal matrix deposition, as evidenced by the irregular alignment of immature collagen fibers. Despite the presence of matrix abnormalities, MMP-9-null wounds displayed normal tensile strength. Ultrastructural analysis of wounds revealed the presence of large collagen fibrils, some with irregular shape. Keratinocyte proliferation, inflammation, and angiogenesis were found to be normal in MMP-9-null wounds. In addition, VEGF levels were similar in control and MMP-9-null wound extracts. To investigate the importance of MMP-9 in wound reepithelialization we tested human and murine keratinocytes in a wound migration assay and found that antibody-based blockade of MMP-9 function or MMP-9 deficiency retarded migration. Collectively, our observations reveal defective healing in MMP-9-null mice and suggest that MMP-9 is required for normal progression of wound closure.

Transforming growth factor-beta signaling in skin: stromal to epithelial cross-talk

In this issue, Denton et al., describe a mouse model of postnatal deletion of the transforming growth factor (TGF)-beta receptor type II (TbetaRII) in skin fibroblasts. Using a tamoxifen-dependent inducible Cre-lox strategy, the authors demonstrate the pivotal role played by TGF-beta signaling in fibroblasts during wound healing. Healing of full-thickness wounds after fibroblast-specific deletion of TbetaRII in the skin was severely impaired and exhibited delayed re-epithelialization. This study emphasizes the importance of fibroblasts in mesenchymal-epithelial interaction in the skin during wound repair.

Lamininα3 LG4 Module Induces Keratinocyte Migration: Involvement of Matrix Metalloproteinase-9

Laminin alpha3 chain, a functionally key subunit of laminin-5, contains a large globular module (G module) which consists of a tandem repeat of five homologous LG modules (LG1-5). We previously demonstrated that the LG4 module of laminin alpha3 chain (alpha3 LG4) induces a matrix metalloproteinase-1 (MMP-1) expression through the interaction with syndecans leading to MAPK activation/IL-1beta expression signaling loop (Utani et al., J. Biol. Chem. 278, 34483-34490, 2003). Here, we show that a recombinant alpha3 LG4 and synthetic peptides containing syndecan binding motif induced a cell motility and a MMP-9 expression in ketarinocytes. The synthetic peptide (A3G756)-induced cell migration and MMP-9 upregulation were inhibited by each application of a heparin and an IL-1 receptor antagonist (IL-1RA), suggesting the involvement of syndecans and IL-1beta autocrine. Furthermore, the A3G756-induced cell motility was inhibited by an MMP-9 inhibitor and a neutralizing antibody of MMP-9, indicating induced cell motility was dependent on an MMP-9 activity. Taken these together, laminin-5 alpha3 LG4 module may play an important role in re-epithelialization at tissue remodeling.

[Toxicity of a new moistening agent and preservative in vitro]

PURPOSE

The use of preservatives such as benzalkonium chloride (BAC) usually increases the toxicity of pharmaceutical tear substitutes. HP-guar has been recently introduced as a new artificial tear substitute and includes the preservative Polyquad (0.001%), which is considered to be non-toxic. We therefore examined the effect of preserved (cetrimide 0.01%) and unpreserved HPMC (hydroxypropylmethyl cellulose) and HP-guar in dose and time-response experiments in a human corneal and conjunctival epithelial cell culture model.

METHODS

Immortalized human conjunctival and corneal epithelial cells were cultured in 96-well plates at 37 degrees C with 5% CO(2) and exposed to the test solutions. The ATP content was quantified by means of a luminescence-based ATP assay, intracellular esterase activity by double fluorescent viability staining (calcein AM/ethidium homodimer D-1) and cell migration by a colony dispersion assay. All experiments were performed in triplicate and repeated at least once. The significance of differences was determined with an unpaired two-sided t-test.

RESULTS

HPMC with preservative severely reduced the ATP content at all concentrations tested. Unpreserved HPMC, however, showed an inhibition of ATP production only at 100% and good esterase activity. HP-guar with and without preservative were found to reduce ATP activity more than unpreserved HPMC, but the unpreserved solution was found to reduce cellular ATP levels significantly more than the preserved solution.

CONCLUSIONS

The new preservative Polyquad induced significantly less cytotoxicity than cetrimide. However, even unpreserved HP-guar can induce cytotoxicity in vitro, while unpreserved HPMC remains a good alternative tear substitute with low cytotoxicity.

Purification of matrix metalloproteinases by column chromatography

Matrix metalloproteinases (MMPs) are zinc endopeptidases composed of 23 members in humans, which belong to a subfamily of the metzincin superfamily. They play important roles in many pathophysiological events including development, organogenesis, angiogenesis, tissue remodeling and destruction, and cancer cell proliferation and progression by degradation of extracellular matrix (ECM) and non-ECM proteins and interaction with various molecules. Here, we present standard protocols for purification of native proMMPs (proMMP-1, -2, -3, -7, -9 and -10) and recombinant MT1-MMP (MMP-14) using conventional column chromatography. Purification steps comprise the initial common step [diethylaminoethyl (DEAE)-cellulose, Green A Dyematrex gel and gelatin-Sepharose columns], the second step for removal of nontarget proMMPs by immunoaffinity columns (anti-MMP-1 and/or anti-MMP-3 IgG-Sepharose columns) and the final step for further purification (IgG-Sepharose, DEAE-cellulose, Zn2+-chelate-Sepharose and/or gel filtration columns). Purified proMMPs and MMP are functionally active and suitable for biochemical analyses. The basic protocol for the purification from culture media takes approximately 7-10 d.

Matrix metalloproteinase control of capillary morphogenesis

Matrix metalloproteinases (MMPs) play crucial roles in a variety of normal (e.g., blood vessel formation, bone development) and pathophysiological (e.g., wound healing, cancer) processes. This is not only due to their ability to degrade the surrounding extracellular matrix (ECM), but also because MMPs function to reveal cryptic matrix binding sites, release matrix-bound growth factors inherent to these processes, and activate a variety of cell surface molecules. The process of blood vessel formation, in particular, is regulated by what is widely classified as the angiogenic switch: a mixture of both pro- and antiangiogenic factors that function to counteract each other unless the stimuli from one side exceeds the other to disrupt the quiescent state. Although it was initially thought that MMPs were strictly proangiogenic, new functions for this proteolytic family, such as mediating vascular regression and generating matrix fragments with antiangiogenic capacities, have been discovered in the last decade. These findings cast MMPs as multifaceted pro- and antiangiogenic effectors. The purpose of this review is to introduce the reader to the general structure and characterization of the MMP family and to discuss the temporal and spatial regulation of their gene expression and enzymatic activity in the following crucial steps associated with angiogenesis: degradation of the vascular basement membrane, proliferation and invasion of endothelial cells within the subjacent ECM, organization into immature tubules, maturation of these nascent vessels, and the pruning and regression of the vascular network.

Fibronectin fragmentation is a feature of periodontal disease sites and diabetic foot and leg wounds and modifies cell behavior

BACKGROUND

Fibronectin (FN) undergoes fragmentation in periodontal disease sites and in poorly healing diabetic wounds. The biologic effects of FN fragments on wound healing remain unresolved. This study characterized the pattern of FN fragmentation and its effects on cellular behavior compared to intact FN.

METHODS

Polyclonal antibodies were raised against FN and three defined recombinant segments of FN and used to analyze gingival crevicular fluid from periodontal disease sites in systemically healthy subjects and in subjects with diabetes, as well as chronic leg and foot wound exudates from subjects with diabetes. Subsequently, the behavior of human gingival fibroblasts (hGFs) and HT1080 reference cells were analyzed by measuring cell attachment, migration, and chemotaxis in the presence of intact FN or recombinant FN fragments.

RESULTS

FN fragmentation was evident in fluids from periodontal disease sites and diabetic leg and foot wounds. However, no fragmentation pattern distinguished systemically healthy subjects from subjects with diabetes. hGFs and HT1080 cells required significantly higher concentrations of FN fragments to achieve attachment comparable to intact FN. Cells cultured on FN fragments also were morphologically different from cells cultured on full-length FN. Migration was reduced for hGFs cultured on FN fragments relative to full-length FN. In contrast, FN fragments increased HT1080 fibrosarcoma cell migration over intact FN.

CONCLUSIONS

FN fragmentation is a prominent feature of periodontal and chronic leg and foot wounds in diabetes. Furthermore, cell culture assays confirmed the hypothesis that exposure to defined FN fragments significantly alters cell behavior.

Matrix metalloproteinases and bone

Matrix metalloproteinases (MMPs) are members of a family of zinc-dependent proteolytic enzymes. Several of the MMPs are expressed at high levels in bone and cartilage in mammals including humans and mice and are capable of cleaving native, undenatured collagens with long uninterrupted triple helices; these MMPs therefore potentially function as collagenases in vivo. Several MMPs expressed in the skeleton appear to function in endochondral ossification during embryonic development and in modeling and remodeling of bone postnatally and later in life. Different functions of MMPs have been elucidated through observations of spontaneous mutations in MMP genes in humans and of targeted mutations in Mmp genes and collagen (substrate) genes in mice. Potential mechanisms to account for effects of these mutations are considered in this review.

Upregulation of matrix metalloproteinase-1 (MMP-1) expression in oral carcinomas of betel quid (BQ) users: roles of BQ ingredients in the acceleration of tumour cell motility through MMP-1

Matrix metalloproteinases (MMPs) are commonly expressed in carcinomas including oral squamous cell carcinomas (OSCCs). On the other hand, some evidences suggested that ingredients of betel quid (BQ) inhibit the activity and/or expression of some MMPs thought to be the pathogenesis of oral submucous fibrosis. This study was to analyse whether MMP-1 expression is inhibited in OSCC specimens from BQ users and in cell lines survived from the challenge of BQ ingredients. We found that MMP-1 mRNA was expressed in all the tested 27 OSCC. Levels of MMP-1 mRNA and protein were significantly elevated in the tested five OSCC specimens than in their adjacent tissues (P<0.001 and 0.05, respectively). Esophageal carcinoma (CE81T/VGH) and OSCC (OECM-1) cell lines survived from the cytotoxic BQ extract (BQE) and arecoline selection process were found to express higher MMP-1 mRNA and protein levels, or to exhibit a significant acceleration of two-dimensional (2D) motility than their non-selected parental cells. The enhanced motility was further demonstrated to be specifically and significantly inhibited by the MMP-1 neutralizing antibody and/or by the transfection of an MMP-1 specific antisense oligodeoxynucleotide. These results suggest that in some carcinomas of the upper aerodigestive tract, BQ usage may upregulate MMP-1 expression in the survived tumour cells, and increase their mobility in an MMP-1-dependent manner.

The importance of proline residues in the structure, stability and susceptibility to proteolytic degradation of collagens

Collagens are among proteins that undergo several post-translational modifications, such as prolyl hydroxylation, that occur during elongation of the nascent chains in the endoplasmic reticulum. The major structural collagens, types I, II and III, have large, uninterrupted triple helices, comprising three polyproline II-like chains supercoiled around a common axis. The structure has a requirement for glycine, as every third residue, and is stabilized by the high content of proline and 4-hydroxyproline residues. Action of prolyl hydroxylases is critical. Spontaneous or targeted genetic defects in prolyl hydroxylases can be lethal or result in severe osteogenesis imperfecta. Prolines, as determinants of substrate specificity and susceptibility, also play a role in degradation of collagen by collagenolytic matrix metalloproteinases (MMPs). Targeted mutations in mice in the collagenase cleavage domain have profound effects on collagen turnover and the function of connective tissues. Prolines are thus critical determinants of collagen structure and function.

Matrix metalloproteinases and diabetic foot ulcers: the ratio of MMP-1 to TIMP-1 is a predictor of wound healing

AIMS

Matrix metalloproteinases (MMPs) play a major role in wound healing: they can degrade all components of the extracellular matrix. In diabetic foot ulcers there is an excess of MMPs and a decrease of the tissue inhibitors of MMPs (TIMPs). This imbalance is probably one cause of impaired healing. However, little is known about changes in MMPs during wound healing.

METHODS

Sixteen patients with neuropathic diabetic foot ulcers participated. Wound fluid was collected regularly during the 12-week follow-up period, for measurement of MMP-1, MMP-2, MMP-8, MMP-9 and TIMP-1. Results were analysed by the degree of wound healing: good healers (defined by a reduction of at least 82% in initial wound surface at 4 weeks) and poor healers (reduction of less than 82% in wound surface at 4 weeks).

RESULTS

In good healers, levels of MMP-8 and -9 secreted by inflammatory cells decreased earlier. The initial levels of MMP-1 were similar in good and poor healers (P = 0.1) but rose significantly at week 2 in good healers (P = 0.039). There was a significant correlation between a high ratio of MMP-1/TIMP-1 and good healing (r = 0.65, P = 0.008). Receiver Operator Curve (ROC) analysis showed that an MMP-1/TIMP-1 ratio of 0.39 best predicted wound healing (sensitivity = 71%, specificity = 87.5%).

CONCLUSIONS

A high level of MMP-1 seems essential to wound healing, while an excess of MMP-8 and -9 is deleterious, and could be a target for new topical treatments. The MMP-1/TIMP-1 ratio is a predictor of wound healing in diabetic foot ulcers.