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

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.

Disease specific urinary biomarkers in the central nervous system

Urinary biomarkers can diagnose and monitor pathophysiologic conditions in the central nervous system (CNS). However, focus is often on single diseases, with limited data on discriminatory capability of this approach in a general setting. Here, we demonstrate that different classes of CNS disease exhibit distinct biomarker patterns, evidence of disease-specific "fingerprinting." Urine from 218 patients with pathology-confirmed tumors or cerebrovascular disease, controls (n = 33) were collected. ELISA and/or bead-based multiplexing quantified levels of 21 putative urinary biomarkers. Analysis identified biomarkers capable of distinguishing each disease from controls and other diseases. Mann-Whitney U tests identified biomarkers with differential expression between disease types and controls (P ≤ 0.001). Subsequent receiver-operating characteristic (ROC) analyses revealed distinguishing biomarkers with high sensitivity and specificity. Areas under the curve (AUCs) ranged 0.8563-1.000 (P values ≤ 0.0003), sensitivities ranged 80.00-100.00%, and specificities ranged 80.95-100.00%. These data demonstrate proof-of-principle evidence that disease-specific urinary biomarker signatures exist. In contrast to non-specific responses to ischemia or injury, these results suggest that urinary biomarkers accurately reflect unique biological processes distinct to different diseases. This work can be used to generate disease-specific panels for enhancing diagnosis, assisting less-invasive follow-up and herald utility by revealing putative disease-specific therapeutic targets.

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.

Wound Fluid Matrix Metalloproteinase-9 as a Potential Predictive Marker for the Poor Healing Outcome in Diabetic Foot Ulcers

Background and Objective

Evidence for the roles of matrix metalloproteinases-9 (MMP-9) in the healing process of diabetic foot ulcers has remained unclear. We therefore aimed to demonstrate the relationship of MMP-9 with the wound healing process and determine its potential usefulness in predicting the wound healing outcome.

Methods

Twenty-two patients with diabetic foot ulcer were recruited. The wound size was determined, and the wound fluid was collected for the measurement of MMP-9 levels using an ELISA during the 12-week follow-up period regularly. The patients were categorized as good healers and poor healers when the wound area reduction was ≥ 50% and < 50% at week 4 when compared to the initial wound size at week 0.

Results

Median wound fluid MMP-9 levels in the poor healer group were shown to be significantly higher than those in the good healer group (1.03 pg/µg protein vs. 0.06 pg/µg protein, p = 0.001), and the levels fluctuated throughout the 12-week follow-up period. In contrast to the poor healer group, the MMP-9 levels were demonstrated to be constantly low throughout the follow-up period in the good healer group. ROC analysis showed that the MMP-9 level of 0.38 pg/µg protein was able to predict the wound healing outcome with the sensitivity of 81.8%, the specificity of 64.6%, and the area under the curve of 0.901 (CI 0.78-1.03, p = 0.001).

Conclusion

These findings suggested that determination of wound fluid MMP-9 levels might become a promising biomarker predicting wound healing outcomes and a novel potential therapeutic target for diabetic foot ulcers.

In vitro molecular study of wound healing using biosynthesized bacteria nanocellulose/silver nanocomposite assisted by bioinformatics databases

Background

In recent years, bacterial nanocellulose (BNC) based nanocomposites have been developed to promote healing property and antibacterial activity of BNC wound dressing. Molecular study can help to better understanding about interaction of genes and pathways involved in healing progression.

Objectives

The aim of this study was to prepare bacterial nanocellulose/silver (BNC/Ag) nanocomposite films as ecofriendly wound dressing in order to assess their physical, cytotoxicity and antimicrobial properties. The in vitro molecular study was performed to evaluate expression of genes involved in healing of wounds after treatment with BNC/Ag biofilms.

Study design materials and methods

Silver nanoparticles were formed by using Citrullus colocynthis extract within new isolated bacterial nanocellulose (BNC) RM1. The nanocomposites were characterized using X-ray diffraction, Fourier transform infrared, and field emission scanning electron microscopy. Besides, swelling property and Ag release profile of the nanocomposites were studied. The ability of nanocomposites to promote wound healing of human dermal fibroblast cells in vitro was studied. Bioinformatics databases were used to identify genes with important healing effect. Key genes which interfered with healing were studied by quantitative real time PCR.

Results

Spherical silver nanoparticles with particle size ranging from 20 to 50 nm were synthesized and impregnated within the structure of BNC. The resulting nanocomposites showed significant antibacterial activities with inhibition zones ranging from 7±0.25 to 16.24±0.09 mm against skin pathogenic bacteria. Moreover, it was compatible with human fibroblast cells (HDF) and could promote in vitro wound healing after 48h. Based on bioinformatics databases, the genes of TGF-β1, MMP2, MMP9, CTNNB1, Wnt4, hsa-miR-29b-3p and hsa-miR-29c-3p played important role in wound healing. The nanocomposites had an effect in expression of the genes in healing. Thus, the BNC/Ag nanocomposite can be used to heal wound in a short period and simple manner.

Conclusion

This eco-friendly nanocomposite with excellent antibacterial activities and healing property confirming its utility as potential wound dressings.

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.

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.

Metalloproteinases and Wound Healing

Significance: Matrix metalloproteinases (MMPs) are present in both acute and chronic wounds. They play a pivotal role, with their inhibitors, in regulating extracellular matrix degradation and deposition that is essential for wound reepithelialization. The excess protease activity can lead to a chronic nonhealing wound. The timed expression and activation of MMPs in response to wounding are vital for successful wound healing. MMPs are grouped into eight families and display extensive homology within these families. This homology leads in part to the initial failure of MMP inhibitors in clinical trials and the development of alternative methods for modulating the MMP activity. MMP-knockout mouse models display altered wound healing responses, but these are often subtle phenotypic changes indicating the overlapping MMP substrate specificity and inter-MMP compensation. Recent Advances: Recent research has identified several new MMP modulators, including photodynamic therapy, protease-absorbing dressing, microRNA regulation, signaling molecules, and peptides. Critical Issues: Wound healing requires the controlled activity of MMPs at all stages of the wound healing process. The loss of MMP regulation is a characteristic of chronic wounds and contributes to the failure to heal. Future Directions: Further research into how MMPs are regulated should allow the development of novel treatments for wound healing.

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.

Polymeric implant materials for the reconstruction of tracheal and pharyngeal mucosal defects in head and neck surgery

The existing therapeutical options for the tracheal and pharyngeal reconstruction by use of implant materials are described. Inspite of a multitude of options and the availability of very different materials none of these methods applied for tracheal reconstruction were successfully introduced into the clinical routine. Essential problems are insufficiencies of anastomoses, stenoses, lack of mucociliary clearance and vascularisation. The advances in Tissue Engineering (TE) offer new therapeutical options also in the field of the reconstructive surgery of the trachea. In pharyngeal reconstruction far reaching developments cannot be recognized at the moment which would allow to give a prognosis of their success in clinical application. A new polymeric implant material consisting of multiblock copolymers was applied in our own work which was regarded as a promising material for the reconstruction of the upper aerodigestive tract (ADT) due to its physicochemical characteristics. In order to test this material for applications in the ADT under extreme chemical, enzymatical, bacterial and mechanical conditions we applied it for the reconstruction of a complete defect of the gastric wall in an animal model. In none of the animals tested either gastrointestinal complications or negative systemic events occurred, however, there was a multilayered regeneration of the gastric wall implying a regular structured mucosa.

In future the advanced stem cell technology will allow further progress in the reconstruction of different kind of tissues also in the field of head and neck surgery following the principles of Tissue Engineering.

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.

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.

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.

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.

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.

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.

Negative-pressure wound therapy: a snapshot of the evidence

Topical negative pressure (TNP) is a mode of therapy used to encourage wound healing. It can be used as a primary treatment for chronic/complex wounds or as an adjunct to surgery. Based on the evidence to date, the clinical effectiveness of negative-pressure therapy is still unclear. Although case reports and retrospective studies have demonstrated enhanced wound healing in acute/traumatic wounds, chronic wounds, infected wounds, wounds secondary to diabetes mellitus, sternal wounds and lower limb wounds, there are very few randomised controlled trials, with unclear results. The evidence is lacking for the use of TNP therapy for other indications to enhance wound healing such as patients with decubitus ulcers, diabetes and peripheral vascular disease and to improve skin graft take. There have been, as yet, no quality-of-life studies available for negative-pressure therapy. Despite this, the usage of TNP has increased. This review provides an overview of clinical studies using TNP and proposes avenues for further research to elucidate the exact mechanism of TNP, in addition to large randomised controlled clinical trials of patients undergoing this therapy.

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.

Transforming growth factor-beta - and tumor necrosis factor-alpha -mediated induction and proteolytic activation of MMP-9 in human skin

Both cytokines and matrix metalloproteinases (MMPs) are active during physiologic and pathologic processes such as cancer metastasis and wound repair. We have systematically studied cytokine-mediated MMP regulation. Cytokine-mediated proteinase induction and activation were initially investigated in organ-cultured human skin followed by determination of underlying cellular and molecular mechanisms using isolated skin cells. In this report we demonstrate that tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) synergistically induce pro-MMP-9 in human skin as well as isolated dermal fibroblasts and epidermal keratinocytes. Furthermore, TNF-alpha promotes proteolytic activation of pro-MMP-9 by conversion of the 92-kDa pro-MMP-9 to the 82-kDa active enzyme. This activation occurred only in skin organ culture and not by either isolated fibroblasts or keratinocyte, although the pro-MMP-9 activation could be measured in a cell-free system derived from TNF-alpha-activated skin. The cytokine-mediated induction of pro-MMP-9 in dermal fibroblasts was evident by increased mRNA. At the transcription level, we examined the cytokine-mediated transactivation of the 5'-region promoter of the human MMP-9 in dermal fibroblasts. The results demonstrated that TNF-alpha and TGF-beta could independently stimulate the 5'-flanking 670-base pair promoter. A TGF-beta-response element (-474) and an NF-kappaB-binding site (-601) were identified to be the cis-elements for TGF-beta or TNF-alpha activation, respectively. Taken together, these findings suggest a specific mechanism whereby multiple cytokines can regulate MMP-9 expression/activation in the cells of human skin. These results imply roles for these cytokines in the regulation of MMP-9 in physiologic and pathologic tissue remodeling.

Regulation of tissue injury responses by the exposure of matricryptic sites within extracellular matrix molecules

Extracellular matrix (ECM) is known to provide signals controlling cell shape, migration, proliferation, differentiation, morphogenesis, and survival. Recent data shows that some of these signals are derived from biologically active cryptic sites within matrix molecules (matricryptic sites) that are revealed after structural or conformational alteration of these molecules. We propose the name, matricryptins, for enzymatic fragments of ECM containing exposed matricryptic sites. Mechanisms regulating the exposure of matricryptic sites within ECM molecules include the major mechanism of enzymatic breakdown as well as others including ECM protein multimerization, adsorption to other molecules, cell-mediated mechanical forces, and ECM denaturation. Such matrix alterations occur during or as a result of tissue injury, and thus, the appearance of matricryptic sites within an injury site may provide important new signals to regulate the repair process. Here, we review the data supporting this concept and provide insight into why the increased exposure of matricryptic sites may be an important regulatory step in tissue responses to injury.