Temporal study of the activity of matrix metalloproteinases and their endogenous inhibitors during wound healing

Alcaligenes faecalis corrects aberrant matrix metalloproteinase expression to promote reepithelialization of diabetic wounds

Chronic wounds are a common and costly complication of diabetes, where multifactorial defects contribute to dysregulated skin repair, inflammation, tissue damage, and infection. We previously showed that aspects of the diabetic foot ulcer microbiota were correlated with poor healing outcomes, but many microbial species recovered remain uninvestigated with respect to wound healing. Here, we focused on Alcaligenes faecalis, a Gram-negative bacterium that is frequently recovered from chronic wounds but rarely causes infection. Treatment of diabetic wounds with A. faecalis accelerated healing during early stages. We investigated the underlying mechanisms and found that A. faecalis treatment promotes reepithelialization of diabetic keratinocytes, a process that is necessary for healing but deficient in chronic wounds. Overexpression of matrix metalloproteinases in diabetes contributes to failed epithelialization, and we found that A. faecalis treatment balances this overexpression to allow proper healing. This work uncovers a mechanism of bacterial-driven wound repair and provides a foundation for the development of microbiota-based wound interventions.

Gelatin‑sodium alginate composite hydrogel doped with black phosphorus@ZnO heterojunction for cutaneous wound healing with antibacterial, immunomodulatory, and angiogenic properties

Hydrogels with novel antimicrobial properties and accelerated wound healing are of great interest in the field of wound dressings because they not only prevent bacterial infections but also fulfill the essential needs of wound healing. In this study, multifunctional hydrogel dressings consisting of black phosphorus nanosheets(BPNS) surface-modified Zinc oxide (BP@ZnO heterojunction) based on gelatin (Gel), sodium alginate (SA), glutamine transferase (mTG), and calcium ions with a three-dimensional crosslinked network were prepared. The BP@ZnO-Gel/SA hydrogel has excellent mechanical properties, hemocompatibility (hemolysis rate: 3.29 %), swelling rate(832.8 ± 19.2 %), cytocompatibility, photothermal and photodynamic antibacterial properties(Sterilization rate: 96.4 ± 3.3 %). In addition, the hydrogel accelerates wound healing by promoting cell migration, immune regulation and angiogenesis. Thus, this hydrogel achieves the triple effect of antimicrobial, immunomodulation and angiogenesis, and is a tissue engineering strategy with great potential.

Microbiota-derived imidazole propionate inhibits type 2 diabetic skin wound healing by targeting SPNS2-mediated S1P transport

Imidazole propionate (ImP) is a recently discovered metabolite of T2DM-related gut microbiota. The effect of ImP on T2DM wound healing has not been studied yet. In this research, the changes of ImP-producing bacteria on the skin are firstly evaluated. 16sRNA sequencing results showed that the abundance of ImP-producing bacteria-Streptococcus in the intestine and skin of T2DM mice is significantly increased. Animal experiments show that ImP can inhibit the process of wound healing and inhibit the formation of blood vessels in the process of wound healing. Molecular mechanism research results show that ImP can inhibit S1P secretion mediated by SPNS2, and inhibit the activation of Rho signaling pathway, thereby affecting the angiogenesis process of HUVEC cells. This work also provides a potential drug HMPA that promotes T2DM wound healing.

Wound microbiota-mediated correction of matrix metalloproteinase expression promotes re-epithelialization of diabetic wounds

Chronic wounds are a common and costly complication of diabetes, where multifactorial defects contribute to dysregulated skin repair, inflammation, tissue damage, and infection. We previously showed that aspects of the diabetic foot ulcer microbiota were correlated with poor healing outcomes, but many microbial species recovered remain uninvestigated with respect to wound healing. Here we focused on Alcaligenes faecalis , a Gram-negative bacterium that is frequently recovered from chronic wounds but rarely causes infection. Treatment of diabetic wounds with A. faecalis accelerated healing during early stages. We investigated the underlying mechanisms and found that A. faecalis treatment promotes re-epithelialization of diabetic keratinocytes, a process which is necessary for healing but deficient in chronic wounds. Overexpression of matrix metalloproteinases in diabetes contributes to failed epithelialization, and we found that A. faecalis treatment balances this overexpression to allow proper healing. This work uncovers a mechanism of bacterial-driven wound repair and provides a foundation for the development of microbiota-based wound interventions.

In-silico Screening of Phytoconstituents on Wound Healing Targets-Approaches and Current Status

Over recent years, there has been tremendous research focused on the effective utilization of natural products in wound management. Natural or herbal products contain several phytoconstituents that may act on various stages in wound healing and thereby provide a multi-targeted approach especially in the treatment of chronic wounds. Currently, attempts have been made to screen the phytoconstituents present in herbs on various targets involved in wound healing. This review includes a systematic evaluation of scientific reports by various groups of researchers on the herbals evaluated for wound management, their phytochemical profiling, pre-clinical studies, and molecular modeling studies. Various wound targets discussed include Interleukin-1, Interleukin-6, Tumor necrosis factor-α (TNF-α), Thymosin beta-4 (Tβ-4) that regulate the early inflammatory stage and the novel T cell immune response cDNA 7(TIRC7) that regulates angiogenesis. Also, neuropeptides P and Y act on the inflammatory, migratory, and proliferation phases, and growth factors like vascular endothelial growth factor family (VEGF) and placental growth factor family (PGF) are involved in angiogenesis, while the role of Fibroblast growth factor in tissue remodeling is discussed. As many of the natural products include polyherbal systems, this approach can help in the judicious selection of a combination of herbs that will act on multiple targets in the wound healing process and provide a multi-factorial approach in wound management.

IL-1β Impaired Diabetic Wound Healing by Regulating MMP-2 and MMP-9 through the p38 Pathway

Diabetes mellitus is one of the most prominent metabolic disorders in the world, and insulin resistance in diabetic patients leads to several complications including increased inflammation and delayed wound healing. Fibroblast migration and reepithelialization play a significant role in wound healing. In this study, we explored the effects of IL-1β signaling on proliferation and migration of human fibroblasts from diabetic wound tissues. We observed elevated levels of IL-1β in samples from diabetic patients when compared to normal wound tissues. At high concentrations, IL-1β inhibited cell proliferation and migration in ex vivo fibroblast cultures. Moreover, expression of matrix metalloproteinases (MMPs) was upregulated, and tissue inhibitor of metalloproteinases (TIMPs) was downregulated in diabetic wound tissues and cells. These effects were regulated by levels of IL-1β. Furthermore, IL-1β induced p38 phosphorylation thereby activating the p38 MAPK pathway that in turn regulated the expression of MMPs and TIMPs. Together, our study identifies a novel mechanism behind delayed wound closure in diabetes mellitus that involves IL-1β-dependent regulation of cell proliferation and migration.

Non-invasive Urinary Biomarkers in Moyamoya Disease

Introduction: A major difficulty in treating moyamoya disease is the lack of effective methods to detect novel or progressive disease prior to the onset of disabling stroke. More importantly, a tool to better stratify operative candidates and quantify response to therapy could substantively complement existing methods. Here, we present proof-of-principle data supporting the use of urinary biomarkers as diagnostic adjuncts in pediatric moyamoya patients.

Methods: Urine and cerebrospinal fluid specimens were collected from pediatric patients with moyamoya disease and a cohort of age and sex-matched control patients. Clinical and radiographic data were paired with measurements of a previously validated panel of angiogenic proteins quantified by ELISA. Results were compared to age and sex-matched controls and subjected to statistical analyses.

Results: Evaluation of a specific panel of urinary and cerebrospinal fluid biomarkers by ELISA demonstrated significant elevations of angiogenic proteins in samples from moyamoya patients compared to matched controls. ROC curves for individual urinary biomarkers, including MMP-2, MMP-9, MMP-9/NGAL, and VEGF, showed excellent discrimination. The optimal urinary biomarker was MMP-2, providing a sensitivity of 88%, specificity of 100%, and overall accuracy of 91%. Biomarker levels changed in response to therapy and correlated with radiographic evidence of revascularization.

Conclusions: We report, for the first time, identification of a panel of urinary biomarkers that predicts the presence of moyamoya disease. These biomarkers correlate with presence of disease and can be tracked from the central nervous system to urine. These data support the hypothesis that urinary proteins are useful predictors of the presence of moyamoya disease and may provide a basis for a novel, non-invasive method to identify new disease and monitor known patients following treatment.

An MMP/TIMP ratio scoring system as a potential predictive marker of diabetic foot ulcer healing

OBJECTIVES

The mechanism of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in diabetic foot ulcers (DFUs) is unclear. The purpose of this study was to describe changes in MMP-1, MMP-9, and TIMP-1 levels during DFU healing, and to search for any correlation in the changes in MMP levels with wound healing, in order to find possible predictors of healing.

METHODS

Patients with a DFU were recruited and placed into two groups, according to the degree of wound healing: 'good healers' and 'poor healers'. Levels of MMP-1, MMP-9, and TIMP-1 were analysed by ELISA (enzyme-linked immunosorbent assay).

RESULTS

A total of 22 patients participated in the study. The MMP-1 level was significantly higher at weeks zero (W0) and 12 (W12) in 'good healers' than in 'poor healers' (p=0.045 and 0.008, respectively). In contrast, the MMP-9 level was significantly lower in 'good healers' than in 'poor healers' at W0, W4, and W12 (p=0.001, 0.001 and 0.028, respectively). Receiver operator curve (ROC) analysis of the MMP-9 level, MMP-1/TIMP-1 ratio, and MMP-9/TIMP-1 ratio at W0 provided cut-off levels of 0.38, 0.056, and 9.06, respectively, which were best predictive of a reduction in wound area at W4 ('good healers' versus 'poor healers'; thereby predicting wound healing condition at W12) with a sensitivity of 81.8%, 81.8%, and 90.9%, and a specificity of 64.6%, 55%, and 64.6%, respectively.

CONCLUSION

A 'poor healing scoring system' is therefore proposed that could be determined on patient admission, which has the potential to be used clinically as a predictor of healing, thus allowing an appropriate treatment plan to be developed.

Angiogenic and MMPs modulatory effects of icariin improved cutaneous wound healing in rats

Icariin is a flavonoid from plant belonging to the genus Epimedium, commonly known as Horny goat weed or Yin Yang Huo. The compound possesses multiple biological activities which are associated with the modulation of many signalling pathways, like NF-κB, Erk-p38-JNK, and release of various cytokines and growth factors. The present study determined wound healing potential of icariin in male Wistar rats. Icariin ointment (0%, 0.004%, 0.02%, 0.1% and 0.5%), was applied daily (b.i.d.) for 14 days on ≈ 400 mm² cutaneous wound in different groups of rats. On day 14 post-wounding, 0.1% and 0.5% icariin treatment significantly (P < 0.01 and P < 0.001, respectively) increased wound contraction, as compared to control. Western blots revealed upregulation of IL-10 and downregulation of NF-κB and TNF-α. Increased expression of CD-31 showed abundance of microvessels in healing tissues after treatment with icariin. The MMP-2 and MMP-9 activities were reduced in icariin treated groups. Masson's trichrome staining revealed relatively better completion of re-epithelisation as well as increased deposition of well organised collagen fibres in the healing tissues compared to control. It is concluded that icariin has potential to accelerate cutaneous wound healing in rats.

Metalloproteinases in chronic and acute wounds: A systematic review and meta-analysis

A systematic review and meta-analysis were undertaken in order to explore the influence of matrix metalloproteinases and their diagnostic methods in chronic and acute wounds. Searches were conducted in the PubMed (Medline) and Embase (Elsevier) databases from inception to late November 2017. We included clinical trials enrolling patients with cutaneous chronic and acute wounds where a validated diagnostic method was employed for metalloproteinases. We excluded in vitro, animal or preclinical studies, nonoriginal articles, and studies without available data for analysis. In addition, references of narrative and systematic reviews were scrutinized for additional articles. Eight studies met the inclusion criteria. Results revealed that the most frequently determined matrix metalloproteinases were MMP-2 and MMP-9, and were found in 54.5% of wounds. MMP-9 was present in more than 50% of the chronic wounds with a range from 37 to 78%. However, metalloproteinases were found in only 20% of acute wounds, and other types of metalloproteinases were also observed (MMP-2 and MMP-3). On the basis of the available evidence, high levels of metalloproteinases have been correlated with significantly delayed wound healing in wounds of a variety of etiologies.

Pathologies of matrix metalloproteinase-2 underactivity: a perspective on a neglected condition 1

A member of the matrix metalloproteinase family, matrix metalloproteinase-2 (MMP-2, gelatinase A), has been extensively studied for its role in both normal physiology and pathological processes. Whereas most research efforts in recent years have investigated the pathologies associated with MMP-2 overactivity, the pathological mechanisms elicited by MMP-2 underactivity are less well understood. Here, we distinguish between 2 states and describe their causes: (i) MMP-2 deficiency (complete loss of MMP-2 activity) and (ii) MMP-2 insufficiency (defined as MMP-2 activity below baseline levels). Further, we review the biology of MMP-2, summarizing the current literature on MMP-2 underactivity in both mice and humans, and describe research being conducted by our lab towards improving our understanding of the pathological mechanisms elicited by MMP-2 deficiency/insufficiency. We think that this research could stimulate the discovery of new therapeutic approaches for managing pathologies associated with MMP-2 underactivity. Moreover, similar concepts could apply to other members of the matrix metalloproteinase family.

Ginsenoside Rb1 Enhances Keratinocyte Migration by a Sphingosine-1-Phosphate-Dependent Mechanism

The cutaneous wound healing process is tightly regulated by a range of cellular responses, including migration. Sphingosine-1-phosphate (S1P) is a signaling lipid produced in keratinocytes (KC) and it is known to stimulate skin wound repair through increased KC migration. Of the multifunctional triterpene ginsenosides, Rb1 enhances cutaneous wound healing process by increasing KC migration, but cellular mechanisms responsible for the Rb1-mediated increase in KC migration are largely unknown. Therefore, we hypothesized that, and assessed whether, Rb1 could stimulate KC migration through S1P-dependent mechanisms. Rb1 significantly increases S1P production by regulating the activity of metabolic conversion enzymes associated with S1P generation and degradation, sphingosine kinase 1 (SPHK1) and S1P lyase, respectively, in parallel with enhanced KC migration. However, blockade of ceramide to S1P metabolic conversion using a specific inhibitor of SPHK1 attenuated the expected Rb1-mediated increase in KC migration. Furthermore, a pan-S1P receptor inhibitor pertussis toxin significantly attenuated Rb1-induced stimulation of KC migration. Moreover, the Rb1-induced increases in KC migration required S1P receptor(s)-mediated activation of ERK1/2 and NF-κB, leading to production of key cutaneous migrating proteins, matrix metalloproteinase (MMP)-2 and MMP-9. Taken together, the results show that Rb1 stimulates KC migration through an S1P→S1P receptor(s)→ERK1/2→NF-κB→MMP-2/-9 pathway. This research revealed a previously unidentified cellular mechanism for Rb1 in enhancing KC migration and pointing to a new therapeutic approach to stimulate the cutaneous wound healing process.

Processed eggshell membrane powder regulates cellular functions and increase MMP-activity important in early wound healing processes

Avian eggshell membrane (ESM) is a natural biomaterial that has been used as an alternative natural bandage to cure wounds, and is available in large quantities from egg industries. We have previously demonstrated that processed eggshell membrane powder (PEP), aiming to be used in a low cost wound healing product, possesses anti-inflammatory properties. In this study, we further investigated effects of PEP on MMP activities in vitro (a dermal fibroblast cell culture system) and in vivo (a mouse skin wound healing model). Three days incubation with PEP in cell culture led to rearrangement of the actin-cytoskeleton and vinculin in focal adhesions and increased syndecan-4 shedding. In addition, we observed increased matrix metalloproteinase type 2 (MMP-2) enzyme activation, without effects on protein levels of MMP-2 or its regulators (membrane type 1 (MT1)-MMP and tissue inhibitor of matrix metalloproteinase type 2 (TIMP-2). Longer incubation (10 days) led to increased protein levels of MMP-2 and its regulators. We also observed an increased alpha-smooth muscle actin (α-SMA) production, suggesting an effect of PEP on myofibroblast differentiation. In vivo, using the mouse skin wound healing model, PEP treatment (3 days) increased MMP activity at the wound edges, along with increased MMP-2 and MMP-9 protein levels, and increased keratinocyte cell proliferation. Altogether, our data suggest PEP stimulates MMP activity, and with a positive effect on early cellular events during wound healing.

Using urinary bFGF and TIMP3 levels to predict the presence of juvenile pilocytic astrocytoma and establish a distinct biomarker signature

OBJECTIVE The authors report the use of urinary biomarkers as a novel, noninvasive technique to detect juvenile pilocytic astrocytomas (JPAs), capable of distinguishing JPAs from other CNS diseases, including other brain tumors. Preliminary screening of an array of tumors implicated proteases (including matrix metalloproteinases [MMPs]) and their inhibitors (tissue inhibitors of metalloproteinase [TIMPs]) as well as growth factors (including basic fibroblast growth factor [bFGF]) as candidate biomarkers. These data led the authors to hypothesize that tissue inhibitor of metalloproteinase 3 (TIMP3) and bFGF would represent high-probability candidates as JPA-specific biomarkers. METHODS Urine was collected from 107 patients, which included children with JPA (n = 21), medulloblastoma (n = 17), glioblastoma (n = 9), arteriovenous malformations (n = 25), moyamoya (n = 14), and age- and sex-matched controls (n = 21). Biomarker levels were quantified with enzyme-linked immunosorbent assay, tumor tissue expression was confirmed with immunohistochemical analysis, and longitudinal biomarker expression was correlated with imaging. Results were subjected to univariate and multivariate statistical analyses. RESULTS Using optimal urinary cutoff values of bFGF > 1.0 pg/μg and TIMP3 > 3.5 pg/μg, multiplexing bFGF and TIMP3 predicts JPA presence with 98% accuracy. Multiplexing bFGF and MMP13 distinguishes JPA from other brain tumor subtypes with up to 98% accuracy. Urinary biomarker expression correlated with both tumor immunohistochemistry and in vitro tumor levels. Urinary bFGF and TIMP3 decrease following successful tumor treatment and correlate with changes in tumor size. CONCLUSIONS This study identifies 2 urinary biomarkers-bFGF and TIMP3-that successfully detect one of the most common pediatric brain tumors with high accuracy. These data highlight potential benefits of urinary biomarkers and support their utility as diagnostic tools in the treatment of children with JPA.

Outcome Measurements in Wound Healing Are Not Inclusive: A Way Forward

Standardized outcome measurement in wound healing has been an elusive goal. Whilst research into wound healing science and technology continues to progress rapidly, the lack of a uniform outcome assessment is making comparative analysis of results difficult. This paper seeks to outline the reported clinical, physiological, and histological outcomes that have been utilized in the literature. A minimal data set base for wound outcome evaluation is also established to be validated by future multivariate analysis of patient data.

Self-Assembled Wound Dressings Silence MMP-9 and Improve Diabetic Wound Healing In Vivo

The direct local delivery of short interfering RNA (siRNA) into target tissues presents a real solution to several complex medical conditions that today lack efficacious therapies. The development of an ultrathin polymer coating is described to sustain the delivery of siRNA for up to 2 weeks in vitro and in vivo. This technology successfully reduces the expression of MMP-9 within the wounds of diabetic mice, significantly accelerating the wound healing process and improving the quality of tissue formed.

A pilot study evaluating protein abundance in pressure ulcer fluid from people with and without spinal cord injury

OBJECTIVE

To determine whether the biochemistry of chronic pressure ulcers differs between patients with and without chronic spinal cord injury (SCI) through measurement and comparison of the concentration of wound fluid inflammatory mediators, growth factors, cytokines, acute phase proteins, and proteases.

DESIGN

Survey.

SETTING

Tertiary spinal cord rehabilitation center and skilled nursing facilities.

PARTICIPANTS

Twenty-nine subjects with SCI and nine subjects without SCI (>18 years) with at least one chronic pressure ulcer Stage II, III, or IV were enrolled.

OUTCOME MEASURES

Total protein and 22 target analyte concentrations including inflammatory mediators, growth factors, cytokines, acute phase proteins, and proteases were quantified in the wound fluid and blood serum samples. Blood samples were tested for complete blood count, albumin, hemoglobin A1c, total iron binding capacity, iron, percent (%) saturation, C-reactive protein, and erythrocyte sedimentation rate.

RESULTS

Wound fluid concentrations were significantly different between subjects with SCI and subjects without SCI for total protein concentration and nine analytes, MMP-9, S100A12, S100A8, S100A9, FGF2, IL-1b, TIMP-1, TIMP-2, and TGF-b1. Subjects without SCI had higher values for all significantly different analytes measured in wound fluid except FGF2, TGF-b1, and wound fluid total protein. Subject-matched circulating levels of analytes and the standardized local concentration of the same proteins in the wound fluid were weakly or not correlated.

CONCLUSIONS

The biochemical profile of chronic pressure ulcers is different between SCI and non-SCI populations. These differences should be considered when selecting treatment options. Systemic blood serum properties may not represent the local wound environment.

Adamts5 deletion blocks murine dermal repair through CD44-mediated aggrecan accumulation and modulation of transforming growth factor β1 (TGFβ1) signaling

ADAMTS5 has been implicated in the degradation of cartilage aggrecan in human osteoarthritis. Here, we describe a novel role for the enzyme in the regulation of TGFβ1 signaling in dermal fibroblasts both in vivo and in vitro. Adamts5(-/-) mice, generated by deletion of exon 2, exhibit impaired contraction and dermal collagen deposition in an excisional wound healing model. This was accompanied by accumulation in the dermal layer of cell aggregates and fibroblastic cells surrounded by a pericellular matrix enriched in full-length aggrecan. Adamts5(-/-) wounds exhibit low expression (relative to wild type) of collagen type I and type III but show a persistently elevated expression of tgfbRII and alk1. Aggrecan deposition and impaired dermal repair in Adamts5(-/-) mice are both dependent on CD44, and Cd44(-/-)/Adamts5(-/-) mice display robust activation of TGFβ receptor II and collagen type III expression and the dermal regeneration seen in WT mice. TGFβ1 treatment of newborn fibroblasts from wild type mice results in Smad2/3 phosphorylation, whereas cells from Adamts5(-/-) mice phosphorylate Smad1/5/8. The altered TGFβ1 response in the Adamts5(-/-) cells is dependent on the presence of aggrecan and expression of CD44, because Cd44(-/-)/Adamts5(-/-) cells respond like WT cells. We propose that ADAMTS5 deficiency in fibrous tissues results in a poor repair response due to the accumulation of aggrecan in the pericellular matrix of fibroblast progenitor cells, which prevents their transition to mature fibroblasts. Thus, the capacity of ADAMTS5 to modulate critical tissue repair signaling events suggests a unique role for this enzyme, which sets it apart from other members of the ADAMTS family of proteases.

Wound Healing Versus Regeneration: Role of the Tissue Environment in Regenerative Medicine

One of the major challenges in the field of regenerative medicine is how to optimize tissue regeneration in the body by therapeutically manipulating its natural ability to form scar at the time of injury or disease. It is often the balance between tissue regeneration, a process that is activated at the onset of disease, and scar formation, which develops as a result of the disease process that determines the ability of the tissue or organ to be functional. Using biomaterials as scaffolds often can provide a "bridge" for normal tissue edges to regenerate over small distances, usually up to 1 cm. Larger tissue defect gaps typically require both scaffolds and cells for normal tissue regeneration to occur without scar formation. Various strategies can help to modulate the scar response and can potentially enhance tissue regeneration. Understanding the mechanistic basis of such multivariate interactions as the scar microenvironment, the immune system, extracellular matrix, and inflammatory cytokines may enable the design of tissue engineering and wound healing strategies that directly modulate the healing response in a manner favorable to regeneration.

Significance of lipid mediators in corneal injury and repair

Corneal injury induces an inflammatory reaction and damages the sensory nerves that exert trophic influences in the corneal epithelium. Alterations in normal healing disrupt the integrity and function of the tissue with undesirable consequences, ranging from dry eye and loss of transparency to ulceration and perforation. Lipids play important roles in this complex process. Whereas lipid mediators such as platelet activating factor (PAF) and cyclooxygenease-2 metabolites contribute to tissue damage and neovascularization, other mediators, such as the lipoxygenase (LOX) derivatives from arachidonic acid, 12- and 15-hydroxy/hydroperoxyeicosatetraenoic acids, and lipoxin A4, act as second messengers for epidermal growth factor to promote proliferation and repair. Stimulation of the cornea with pigment epithelial derived factor in the presence of docosahexaenoic acid gives rise to the synthesis of neuroprotectin D1, a derivative of LOX activity, and increases regeneration of corneal nerves. More knowledge about the role that lipids play in corneal wound healing can provide insight into the development of new therapeutic approaches for treating corneal injuries. PAF antagonists, lipoxins, and neuroprotectins can be effective therapeutic tools for maintaining the integrity of the cornea.

Delayed wound healing in elderly people

Our ability to heal wounds deteriorates with age, leading in many cases to a complete lack of repair and development of a chronic wound. Moreover, as the elderly population continues to grow the prevalence of non-healing chronic wounds is escalating. Cutaneous wound repair occurs through a combination of overlapping phases, including an initial inflammatory response, a proliferative phase and a final remodelling phase. In elderly subjects the inflammatory response is delayed, macrophage and fibroblast function compromised, angiogenesis reduced and re-epithelialization inhibited. Whilst a large body of historic research describes the defective processes that lead to delayed healing, only recently have the molecular mechanisms by which these defects arise begun to be elucidated. Current therapies available for treatment of chronic wounds in elderly people are surprisingly limited and generally ineffective. Thus there is an urgent need to develop new therapeutic strategies based on these recent molecular and cellular insights.

Mechanical strain enhances survivability of collagen micronetworks in the presence of collagenase: implications for load-bearing matrix growth and stability

There has been great interest in understanding the methods by which collagen-based load-bearing tissue is constructed, grown and maintained in vertebrate animals. To date, the responsibility for this process has largely been placed with mesenchymal fibroblastic cells that are thought to fully control the morphology of load-bearing extracellular matrix (ECM). However, given clear limitations in the ability of fibroblastic cells to precisely place or remove single collagen molecules to sculpt tissue, we have hypothesized that the material itself must play a critical role in the determination of the form of structural ECM. We here demonstrate directly, using live, dynamic, differential interference contrast imaging, that mechanically strained networks of collagen fibrils, exposed to collagenase (Clostridium histolyticum), degrade preferentially. Specifically, unstrained fibrils are removed 'quickly', while strained fibrils persist significantly longer. The demonstration supports the idea that collagen networks are mechanosensitive in that they are stabilized by mechanical strain. Thus, collagen molecules (together with their complement enzymes) may comprise the basis of a smart, load-adaptive, structural material system. This concept has the potential to drastically simplify the assumed role of the fibroblast, which would need only to provide ECM molecules and mechanical force to sculpt collagenous tissue.

In vivo effect of hyperbaric oxygen on wound angiogenesis and epithelialization

Hyperbaric oxygen (HBO) therapy is increasingly being used in different areas of medical practice. While demonstrated to be effective in several settings, its mechanism of action is not well understood. In the present study, we determined the effects of HBO on wound epithelialization and neovascularization in an in vivo hairless mouse ear "impaired" wound model. To impair wound healing, macrophages were depleted by pretreatment with iota-carrageenan. Wound epithelialization and neovascularization were measured using intravital microscopy and computerized planimetry. Metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and tumor necrosis factor-alpha (TNF-alpha) were measured on days 2 and 7 using immunohistochemistry. In nonimpaired healing wounds, the rate of epithelialization and neovascularization was significantly accelerated in the groups treated with HBO. Time to wound closure was significantly delayed in impaired compared with nonimpaired healing wounds and HBO treatment completely reversed this delay. Neither HBO treatment nor macrophage depletion caused significant alterations in MMP-2 expression in wounds. In contrast, TNF-alpha, MMP-9, and TIMP-1 were significantly up-regulated in the impaired healing group receiving HBO treatment. These results show that HBO therapy effectively reversed the negative effect exerted by macrophage reduction on wound epithelialization and neovascularization. This beneficial effect could be due to stimulation of TNF-alpha production and, to a lesser degree due to release of metalloproteinases.

Interactions between extracellular matrix and growth factors in wound healing

Dynamic interactions between growth factors and extracellular matrix (ECM) are integral to wound healing. These interactions take several forms that may be categorized as direct or indirect. The ECM can directly bind to and release certain growth factors (e.g., heparan sulfate binding to fibroblast growth factor-2), which may serve to sequester and protect growth factors from degradation, and/or enhance their activity. Indirect interactions include binding of cells to ECM via integrins, which enables cells to respond to growth factors (e.g., integrin binding is necessary for vascular endothelial growth factor-induced angiogenesis) and can induce growth factor expression (adherence of monocytes to ECM stimulates synthesis of platelet-derived growth factor). Additionally, matrikines, or subcomponents of ECM molecules, can bind to cell surface receptors in the cytokine, chemokine, or growth factor families and stimulate cellular activities (e.g., tenascin-C and laminin bind to epidermal growth factor receptors, which enhances fibroblast migration). Growth factors such as transforming growth factor-beta also regulate the ECM by increasing the production of ECM components or enhancing synthesis of matrix degrading enzymes. Thus, the interactions between growth factors and ECM are bidirectional. This review explores these interactions, discusses how they are altered in difficult to heal or chronic wounds, and briefly considers treatment implications.

Review: Finding the Culprit: A Review of the Influences of Proteases on the Chronic Wound Environment

Chronic leg ulcers are a complex medical condition with varied underlying causes and requiring diverse treatment strategies. It is generally accepted that chronic ulcers occur when the normal wound healing process is interrupted. These wounds are characterized by excessive protease activity, abundant granulation tissue, and decreased levels of growth factors, resulting in an overall poor prognosis for the patient. Many studies have focused on identifying the key proteases, specifically matrix metalloproteinases (MMPs), responsible for an ulcer's chronicity. Of note, the results of these studies are often conflicting. This report therefore focuses on a review of this literature to identify which MMPs are important in terms of ulcer prognosis and healing outcome. This has revealed that MMPs are clearly important in many biological processes in wound healing, hence are critical to consider when developing improved therapies to enhance both ulcer healing times and ulcer healing outcomes.

Enhanced angiogenesis and reduced contraction in thrombospondin-2-null wounds is associated with increased levels of matrix metalloproteinases-2 and -9, and soluble VEGF

Thrombospondin-2 (TSP2) is an inhibitor of angiogenesis with pro-apoptotic and anti-proliferative effects on endothelial cells. Mice deficient in this matricellular protein display improved recovery from ischemia and accelerated wound healing associated with alterations in angiogenesis and extracellular matrix remodeling. In this study, we probed the function of TSP2 by performing a detailed analysis of dermal wounds and wound-derived fibroblasts. Specifically, we analyzed incisional wounds by tensiometry and found no differences in strength recovery between wild-type and TSP2-null mice. In addition, analysis of full-thickness excisional wounds by terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling stain and MIB-5 immunohistochemistry revealed similar numbers of apoptotic and proliferating cells, respectively. In contrast, the levels of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitors of metalloproteinase (TIMP)-1, TIMP-2, and soluble vascular endothelial growth factor were increased in wounds of TSP2-null mice. Evaluation of the ability of TSP2-null wound fibroblasts to contract collagen gels revealed that it was compromised, even though TSP2-null wounds displayed normal myofibroblast content. Therefore, we conclude that the lack of TSP2 leads to aberrant extracellular matrix remodeling, increased neovascularization, and reduced contraction due in part to elevated levels of MMP-2 and MMP-9. These observations provide in vivo supporting evidence for a newly proposed function of TSP2 as a modulator of extracellular matrix remodeling.

Angiogenic laminin-derived peptides stimulate wound healing

Acceleration of the wound healing process by using angiogenic peptides has been demonstrated previously. Here we used select laminin-111 peptides, A13 and C16, from the laminin alpha1 and gamma1 chain, respectively, to test whether they are able to stimulate wound healing in a rat full thickness wound model. The 12-mer peptides C16 and A13 are highly angiogenic and bind to integrins alphavbeta3 and alpha5beta1. We show that A13 increases wound re-epithelialization as much as 17% over controls by day 4 and C16 increases coverage by 11%. Contraction of the treated wounds was increased as much as 11% for A13 and 8% for C16 at day 4. No differences were observed at day 7 with either peptide. The peptides also stimulated fibroblast migration in Boyden chamber assays. A13 increased cell migration as much as 2.4-fold on uncoated filters and as much as 16-fold on collagen type IV-coated filters over negative controls. Similarly, C16 also stimulated migration 1.8-fold on uncoated filters and as much as 12-fold on collagen-coated filters. A13 and C16 significantly decreased expression of the pro and active forms of matrix metalloproteinase 2 in foreskin fibroblasts indicating their role in collagen accumulation. We conclude that small bioactive angiogenic peptides can promote dermal wound healing and may offer a new class of stable and chemically manipulable therapeutics for wound healing.

Comparison of matrix metalloproteinase 9 and brain natriuretic peptide as clinical biomarkers in chronic heart failure

BACKGROUND

Matrix metalloproteinase 9 (MMP-9) may serve as a biomarker of ventricular remodeling in selected populations, but few studies have assessed its performance in clinical practice. We tested MMP-9 as a biomarker of remodeling and predictor of outcomes in a systolic heart failure cohort derived from clinical practice and compared its performance to brain natriuretic peptide (BNP).

METHODS

Plasma MMP-9 and BNP levels were measured in 395 outpatients with systolic heart failure who participated in the Penn Heart Failure Study. We tested for (1) cross-sectional associations between biomarker levels, left ventricular end-diastolic dimension index (LVEDDI), and ejection fraction (EF), and (2) associations between baseline biomarker levels and risk of subsequent cardiac hospitalization or death over 3 years of follow-up.

RESULTS

Matrix metalloproteinase 9 had no significant correlation with LVEDDI (rho = 0.04, P = not significant) or EF (rho = -0.06, P = not significant), whereas BNP showed highly significant correlations (LVEDDI: rho = -0.27, P < .0001; EF: rho = -0.35, P < .0001). In multivariate linear regression models, MMP-9 again showed no significant associations with LVEDDI (P = .6) or EF (P = .14), whereas BNP showed strong independent associations (LVEDDI: P < .001; EF: P = .002). Kaplan-Meier analyses showed no difference in hospital-free survival by baseline MMP-9 tertile (P = .7), whereas higher BNP tertile predicted worse survival (P < .0001). In multivariate Cox models, baseline MMP-9 level did not predict risk of adverse outcome (hazard ratio for log increase 0.98, P = .9), whereas BNP was a significant independent predictor (hazard ratio for log increase 1.15, P = .02).

CONCLUSION

Compared to BNP, MMP-9 is a poor clinical biomarker of remodeling and outcome in patients with systolic heart failure derived from clinical practice.

Incarcerated massive incisional hernia: extensive necrosis of the colon in a very obese patient. Surgical treatment and vacuum-assisted closure therapy: a case report

We discuss a diabetic obese patient with an extensive necrosis of the ascending and transverse colon plus segmental necrosis of the small bowel incarcerated in a massive median incisional hernia below the umbilicus. After a blood test and an abdominal CT scan (without contrast dial), the patient underwent an urgent operation. We performed an extended right hemicolectomy, multiple segmental small bowel resections and a terminal ileostomy. The defect of the abdominal wall was treated with vacuum-assisted closure (VAC) therapy with good results.

Proteolytic activation of matrix metalloproteinase-9 in skin wound healing is inhibited by alpha-1-antichymotrypsin

An excessive amount of matrix metalloproteinase-9 (MMP-9) has been well documented in inflammatory diseases, including chronic wounds and cancers. Secreted as a zymogen, proMMP-9 can be irreversibly converted to a mature form through cleavage of the N-terminal propeptide domain. Although the converting enzyme for proMMP-9 in human tissues is unknown, we previously found that tumor necrosis factor-alpha (TNF-alpha) promotes activation of proMMP-9 in human skin, and characterized the converting activities as tissue-associated chymotrypsin-like proteinases. On the other hand, the pathophysiologic inhibitor to prevent proMMP-9 maturation also remains elusive. In this regard, we observed the presence of the inhibitory property in burn blister fluid that abrogates the skin extract-mediated activation of proMMP-9. Then we determined that alpha-1-antichymotrypsin (alpha-ACT), an acute-phase factor abundantly present in the blister, effectively inhibited proMMP-9 activation in human and rodent skin. In contrast, the aminophenylmercuric acetate-induced "cysteine switch" and activation of proMMP-9 were not affected by alpha-ACT. TNF-alpha-induced activation of proMMP-9 by the explants of human skin was inhibited by alpha-ACT but not by related alpha-1-antitrypsin. alpha-ACT specifically attenuated maturation of proMMP-9 but not proMMP-2 or proMMP-13. Furthermore, short peptides that mimic the reactive center loop (RCL) of alpha-ACT were sufficient to inhibit the conversion. Mutation analysis demonstrated that a conserved leucine within the RCL was critical for alpha-ACT-exerted inhibition. In chronic wounds, a large amount of mature MMP-9 was associated with fragmentation and inactivation of alpha-ACT. Taken together, these results demonstrate that, to the best of our knowledge, alpha-ACT is a previously unreported pathophysiologic inhibitor that controls proMMP-9 activation in skin tissue.

The effects of chymase on matrix metalloproteinase-2 activation in neointimal hyperplasia after balloon injury in dogs

Chymase is known to generate angiotensin II in the vascular wall. In this study we investigated a novel role for chymase other than angiotensin II production in vascular proliferation after balloon injury. Chymase promoted the migration of vascular smooth muscle cells in the matrix-coated invasion chambers and activated promatrix metalloproteinase-2 obtained from the culture medium of vascular smooth muscle cells. Two weeks after balloon injury, significant neointimal formation was found in dog carotid arteries. After injury, active matrix metalloproteinase-2 was increased in parallel with the augmentation of chymase activity that was seen in the proliferating region of the vascular wall. The oral administration of NK3201 (1 mg/kg per day), a chymase inhibitor, prevented neointimal formation and significantly suppressed both active matrix metalloproteinase-2 and chymase activities 2 weeks after injury. These results suggest that chymase inhibitors can prevent the development of intimal hyperplasia via the inhibition of matrix metalloproteinase-2 activation in balloon-injured arteries.

Influence of the surface structure of a multiblock copolymer on the cellular behavior of primary cell cultures of the upper aerodigestive tractin vitro

The influence of the surface topography of a biodegradable copolymer on adhesion, proliferation, and cellular activity of primary cell cultures of the upper aerodigestive tract (ADT) was investigated. On the basis of the important functions of matrix metalloproteinases (MMPs) and their endogenous inhibitors, tissue inhibitor of MMPs (TIMPs) in regulating extracellular matrix remodeling, cellular adhesion and growth, the appearance and kinetics of these enzymes were investigated in primary cells of the upper ADT seeded on different surfaces of a polymeric biomaterial. Primary cell cultures of the upper ADT of Sprague-Dawley rats were seeded on different surfaces (smooth versus rough surface) of a biodegradable multiblock copolymer and on polystyrene surface as control. Conditioned media of the primary cells were analyzed for MMPs and TIMPs by both zymography and radiometric enzyme assay. Cell adhesion and proliferation as well as the kinetics of appearance and activity level of MMP-1, MMP-2, and TIMPs were significantly different depending on the cell type and the surface structure of the multiblock copolymer. In this study, the data obtained indicated that surface topography governed the biological response to biomaterials. Knowledge as to how cells interact with the interface of biomaterials will be necessary in order to eventually design the "ideal" surface of biomaterials, which will be both tissue and organ-optimized in order to best provide clinicians with specific and viable novel therapeutical options in medicine.

Expression of matrix metalloproteinases and growth factors in diabetic foot wounds treated with a protease absorbent dressing

Wound healing in diabetes is impaired, and nonhealing ulceration represent clinically relevant complications. Persistently high levels of matrix metalloproteases (MMPs) contribute to wound chronicity. Thus, the topical use of protease inhibitors might influence wound healing and promote transition from a chronic to an acute wound.

METHODS

In this study, 33 patients with chronic diabetic foot lesions (stage 2a of the University of Texas Wound Classification system) were included. Fifteen patients received redundant "good standard wound care." In addition, 18 patients were treated with a protease inhibitory modulating matrix (the OCR/collagen Promogran matrix, Ethicon) with dressings changed on a daily basis. Prior to treatment and at 4 and 8 days after treatment, two 3-mm punch biopsies were taken from the center of the wounds and analyzed using ELISA techniques for MMPs, tissue inhibitor of MMP-2 (TIMP-2), and interleukin-1beta (IL-1beta) levels. In addition, mRNA levels of MMPs as well as IL-1beta and TNF-alpha were detected using quantitative real-time polymerase chain reaction (TaqMan, Applied Biosystems, Weiterstadt, Germany).

RESULTS

No differences were detected between both groups and at the three time points for the mRNA levels of MMPs as well as of IL-1beta and TNF-alpha. In addition, MMP levels in wound tissue (analyzed by ELISA) were also not significantly different between both groups. However, IL-1beta was increased on day 8 in the treatment group (P=.01) only. Interestingly, we found a significant reduction of the MMP-9/TIMP-2 ratio in the group being treated with the ORC/collagen. These wounds exhibited a more rapid healing rate when treated with the ORC/collagen matrix.

CONCLUSIONS

The local treatment with a protease inhibitor has a beneficial effect on wound healing. In contrast to the data on wound fluid, our study demonstrated for the first time the unaltered mRNA levels of MMPs during treatment with a protease inhibitory modulating matrix. At the cellular level, MMPs were also not statistically different. However, the more relevant ratio of MMP-9/TIMP-2 was decreased in the treatment group. An equally important finding was that we did not detect a compensatory increase in the MMP-RNA expression even though wound size was clearly reduced.

Molecular balance of capillary tube formation versus regression in wound repair: role of matrix metalloproteinases and their inhibitors

In this review, we discuss the identification of distinct matrix metalloproteinases (MMPs) and their inhibitors that differentially control the processes of capillary tube formation (morphogenesis) versus capillary tube regression in three-dimensional (3D) collagen matrices. This work directly relates to both granulation tissue formation and regression during wound repair. The membrane metalloproteinase, MT1-MMP (MMP-14), is required for endothelial cell (EC) tube formation using in vitro assays that mimic vasculogenesis or angiogenic sprouting in 3D collagen matrices. These events are markedly blocked by small interfering RNA (siRNA) suppression of MT1-MMP in ECs or by addition of tissue inhibitor of metalloproteinases (TIMPs)-2,-3, and -4 but not TIMP-1. In contrast, MMP-1 and MMP-10 are strongly induced during EC tube formation to regulate the process of tube regression (following activation by serine proteases) rather than formation. TIMP-1, which selectively inhibits soluble MMPs, blocks tube regression by inhibiting MMP-1 and MMP-10 while having no influence on EC tube formation. siRNA suppression of MMP-1 and MMP-10 markedly blocks tube regression without affecting tube formation. Furthermore, we discuss that pericyte-induced stabilization of EC tube networks in our model system appears to occur through EC-derived TIMP-2 and pericyte-derived TIMP-3 to block both the capillary tube formation and regression pathways.

Increased expression of matrix metalloproteinase-9 in the eutopic endometrial tissue of women with endometriosis

BACKGROUND

Endometriosis is a disease where endometrial tissue implants in ectopic locations. Remodelling of the extracellular matrix (ECM) is a prerequisite for the implantation of this tissue to be possible.

METHODS

In this study, we detected immunoreactive matrix metalloproteinase-9 (MMP-9) throughout endometrial tissue and identified von Willebrand factor (vWF)-positive endothelial cells, CD45-positive leukocytes, CD3-positive T lymphocytes and CD68-positive macrophages as cells expressing MMP-9 in the stroma.

RESULTS

We found an increased expression of MMP-9 in the uterine endometrial tissue of women with endometriosis, as assessed by zymography and enzyme-linked immunosorbent assay (ELISA) (P < 0.05). However, RT-PCR did not show a statistically significant increase in MMP-9 mRNA expression in these tissues (P = 0.14). There was no significant difference between women with and without endometriosis in the expression of tissue inhibitor of MMPs (TIMP)-1, a known natural inhibitor of the pro- and active forms of MMP-9, whether tested by ELISA or by RT-PCR (P = 0.46 and 0.37, respectively). Interestingly, the ratio of MMP-9/TIMP-1 expression was significantly higher in women with endometriosis than in normal women both at the protein and the mRNA levels (P < 0.05).

CONCLUSION

These findings make plausible the involvement of MMP-9/TIMP-1 imbalance in the invasiveness of the endometrial tissue of patients with endometriosis and the ectopic development of the disease.

Microdeformational Wound Therapy

The vacuum-assisted closure (VAC) device causes microdeformations of the wound surface in contact with the foam. Because angiogenesis and matrix metalloproteinase (MMP) activity are altered in chronic wounds, we hypothesized that microdeformations stimulate capillary formation and affect MMP activity. A VAC device was used to deliver microdeformational wound therapy (MDWT) to the chronic wounds of 3 debilitated patients. Debrided tissue was obtained from wound areas with and without foam contact. Microvessel density and MMP activity were determined by immunohistochemistry and zymography, respectively. Microvessel density of MDWT-treated wounds was 4.5% (+/-0.8) compared with areas not covered by foam [1.6% (+/-0.1)] (P = 0.05) during the first week of treatment and 2.7% (+/-0.3) compared with untreated tissue [1.3% (+/-0.1)] (P = 0.03) during the second treatment week. Wounds subjected to MDWT had greater microvessel density compared with the same wound prior to treatment [1.5% (+/-0.3)] (P = 0.02). MMP-9/NGAL (neutrophil gelatinase-associated lipocalin), MMP-9, latent MMP-2, and active MMP-2 were reduced by 15%-76% in MDWT-treated wounds. MDWT provides a favorable wound-healing environment by increasing angiogenesis and decreasing MMP activity in chronic wounds.

Interleukin-1alpha-induced proteolytic activation of metalloproteinase-9 by human skin

BACKGROUND

Increased activity of matrix metalloproteinase-9 (MMP-9) has been well documented in many diseases associated with inflammation, such as chronic wounds, bullous pemphigoid, liver failure, and tumor metastases. The mechanism for the proteolytic activation of pro-MMP-9 in human tissue still remains unknown.

METHODS

We investigated this mechanism through reconstitution of an inflammatory condition in normal human skin, and epidermal and dermal cells derived from skin. Normal human skin was cultured with exogenous cytokines associated with inflammation and tissue repair. MMP-9 induction and activation were measured, and potential mechanisms were probed by inhibitors.

RESULTS

Pathophysiologic concentrations of interleukin (IL)-1alpha rapidly induced pro-MMP-9 synthesis by human skin. In contrast, IL-1-induced activation of pro-MMP-9 was a slow process, which required 3 days. Tumor growth factor-beta induced pro-MMP-9 but failed to promote activation of the precursor. When the skin was stimulated with the combination of tumor growth factor-beta and IL-1alpha, substantial induction and activation of pro-MMP-9 occurred. This IL-1 induced activation of pro-MMP-9 was observed in intact skin but not in isolated dermal fibroblasts or keratinocytes. IL-1-induced activation of pro-MMP-9 was inhibited by chymostatin, a chymotrypsinlike proteinase inhibitor. Furthermore, IL-1alpha decreased tissue inhibitor of metalloproteinase 1 without changing MMP-9 activator activity.

CONCLUSIONS

The proteolytic activation of pro-MMP-9 in skin inflammatory diseases likely occurs via a pathway including IL-1alpha. The activation is mediated by downregulation of tissue inhibitor of MMP-1 and involves an as yet unidentified chymotrypsinlike proteinase.

Membrane independent activation of fibroblast proMMP-2 by snake venom: novel roles for venom proteinases

ProMMP-2 activation by Bothrops asper venom was investigated in mouse gastrocnemius muscle, mammalian cell culture and a cell-free system. Zymography revealed an increment of latent and activated forms of MMP-2 in muscle homogenates 1-3 days after venom injection. To clarify if venom can induce expression and activation of MMP-2, independently of the inflammatory response, venom was added to cultured human fibroblasts, endothelial and skeletal muscle cells, which expressed proMMP-2 constitutively. Venom activated proMMP-2 without promoting its expression. Venom also activated and degraded proMMP-2 in supernatants collected from fibroblast cultures, indicating that cells are not required for this activation. Pretreatment with EDTA increased MMP-2 activation and reduced degradation. Venom serine proteinases activated proMMP-2, whereas BaP1, a P-I metalloproteinase, predominantly degraded the latent and active forms of MMP-2. Moreover, pretreatment of conditioned medium with serine proteinase inhibitors greatly reduced the venom-induced activation, suggesting that venom proteinases activate MMP-2 via a serine proteinase secreted by fibroblasts. Venom also directly activated and degraded purified proMMP-2, albeit requiring a high concentration. Thus, B. asper venom proteinases activate and degrade proMMP-2 without inducing its synthesis. Serine proteinases play a dominant role in the activation, whereas metalloproteinases predominantly degrade MMP-2. Activation of proMMP-2 by snake venom proteinases, independently of the MT1-MMP/TIMP-2 pathway, extracellular matrix degradation or apoptosis, represents a novel mechanism in human fibroblasts.

Effects of matrix metalloproteinase-3 gene transfer by electroporation in glaucoma filter surgery

To develop gene therapy that can be applied to glaucoma-filtering surgery, we studied effects of transfection of matrix metalloproteinase-3 (MMP-3) cDNA into rabbit conjunctiva by electroporation (EP) on changes of intraocular pressure (IOP) and bleb formation after glaucoma filtering surgery. pTracer-CMV2 vector containing MMP-3 cDNA was transfected into rabbit conjunctiva by EP and MMP-3 expression was studied by reverse transcription (RT)-PCR, zymography and western blot analysis. Three days after the EP transfection of MMP-3 cDNA or vector alone into rabbit conjunctiva, trabeculectomy was performed at the place of transfection in the presence or absence of 0.04% mitomycin C (MMC). Then changes in IOPs and bleb formation were compared with each other. Expression of MMP-3 was detected in conjunctiva until 30 days after transfection by EP. Trabeculectomy following MMP-3 transfection caused significantly longer survival of filtering bleb and decreased levels of IOP in comparison with controls (trabeculectomy alone or trabeculectomy following vector transfection), and these levels were almost identical to those of trabeculectomy with MMC. The present study indicates that EP is effective to transfect some genes that promote the filtering bleb formation in glaucoma surgery, such as MMP-3 gene, and this may be potentially applicable to glaucoma-filtering surgery in glaucoma patients.

Effects of Tumor Necrosis Factor-α (TNFα) in Epidermal Keratinocytes Revealed Using Global Transcriptional Profiling

Identification of tumor necrosis factor-alpha (TNF alpha) as the key agent in inflammatory disorders, e.g. rheumatoid arthritis, Crohn's disease, and psoriasis, led to TNF alpha-targeting therapies, which, although avoiding many of the side-effects of previous drugs, nonetheless causes other side-effects, including secondary infections and cancer. By controlling gene expression, TNF alpha orchestrates the cutaneous responses to environmental damage and inflammation. To define TNF alpha action in epidermis, we compared the transcriptional profiles of normal human keratinocytes untreated and treated with TNF alpha for 1, 4, 24, and 48 h by using oligonucleotide microarrays. We found that TNF alpha regulates not only immune and inflammatory responses but also tissue remodeling, cell motility, cell cycle, and apoptosis. Specifically, TNF alpha regulates innate immunity and inflammation by inducing a characteristic large set of chemokines, including newly identified TNF alpha targets, that attract neutrophils, macrophages, and skin-specific memory T-cells. This implicates TNF alpha in the pathogenesis of psoriasis, fixed drug eruption, atopic and allergic contact dermatitis. TNF alpha promotes tissue repair by inducing basement membrane components and collagen-degrading proteases. Unexpectedly, TNF alpha induces actin cytoskeleton regulators and integrins, enhancing keratinocyte motility and attachment, effects not previously associated with TNF alpha. Also unanticipated was the influence of TNF alpha upon keratinocyte cell fate by regulating cell-cycle and apoptosis-associated genes. Therefore, TNF alpha initiates not only the initiation of inflammation and responses to injury, but also the subsequent epidermal repair. The results provide new insights into the harmful and beneficial TNF alpha effects and define the mechanisms and genes that achieve these outcomes, both of which are important for TNF alpha-targeted therapies.

Weight loss-induced calciphylaxis: potential role of matrix metalloproteinases

Calciphylaxis is an uncommon and often devastating syndrome of calcification of small vessels, leading to tissue infarction. The mechanism of how calcium deposits on small vessels is unknown. Recently, metalloproteinase digestion of elastin has been shown to enhance deposition of calcium, suggesting a possible mechanism of calciphylaxis. We describe a case of a patient who developed calciphylaxis after rapid weight loss, but had normocalcemia and normal renal function. She was found to have high levels of matrix metalloproteinases, which may have chemically altered elastin, allowing deposition of calcium on small vessels. Inhibitors of matrix metalloproteinases may be useful in the prevention and treatment of calciphylaxis.