Matrix metalloproteinase-10 effectively reduces infarct size in experimental stroke by enhancing fibrinolysis via a thrombin-activatable fibrinolysis inhibitor-mediated mechanism

Different Anti-inflammatory Drugs on High-Sensitivity C-Reactive Protein in Patients After Percutaneous Coronary Intervention: A Pilot Randomized Clinical Trial

ABSTRACT

Colchicine reduces atherothrombotic cardiovascular events in coronary artery disease because of its anti-inflammatory effect. However, the effects of the other anti-inflammatory drugs in coronary artery disease remain unclear. This study included 132 patients aged 18-80 years who completed the planned percutaneous coronary interventions and were treated with aggressive secondary prevention strategies for 4 weeks. The subjects were randomly assigned to 1 of the following treatment groups for 4 weeks: (1) control: no additional intervention; (2) colchicine: 0.5 mg once a day; (3) tranilast: 0.1 g thrice a day; or (4) oridonin: 0.5 g thrice a day. The primary outcome was the percentage change in high-sensitivity C-reactive protein (hsCRP) levels at the end of 4 weeks. In total, 109 patients completed the study. The mean age was 58.33 years, 81 (74.31%) were male, and 28 (25.69%) were female. The percentage changes in hsCRP after 4 weeks of treatment were -11.62%, -48.28%, -21.60%, and -7.81%, in the control, colchicine, tranilast, and the oridonin groups, respectively. Compared with the control group, only the colchicine group showed significantly greater reduction in hsCRP levels ( P = 0.022). In targeted proteomic analysis, proteins associated with neutrophil activation (azurocidin, myeloperoxidase, and myeloblastin), platelet aggregation (glycoprotein VI), and endothelial damage (galectin-3) were reduced with colchicine therapy. These results show that of 3 anti-inflammatory drugs only colchicine could reduce hsCRP in patients after percutaneous coronary interventions.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

CM-352 EFFICACY IN A MOUSE MODEL OF ANTICOAGULANT-ASSOCIATED INTRACRANIAL HAEMORRHAGE

BACKGROUND

Intracranial haemorrhage (ICH) is one of the major devastating complications of anticoagulation. Matrix metalloproteinases (MMPs) inhibition has been proposed as a novel pharmacological approach for ICH treatment.

OBJECTIVES

We evaluated the effects of CM-352 (MMPs-fibrinolysis inhibitor) in an experimental ICH model associated with oral anticoagulants as compared with clinically used prothrombin concentrate complex (PCC).

METHODS

ICH was induced by collagenase injection into the striatum of WT (C57BL/6J) anticoagulated mice (warfarin or rivaroxaban) and Mmp10 -/- mice. Hematoma volume and neurological deficits were measured 24h later by diaminobenzidine staining and different behavioural test. Circulating plasminogen activator inhibitor-1 (PAI-1) activity and interleukin-6 (IL-6) were measured in plasma samples and local inflammation was assessed by neutrophil infiltration. Finally, fibrinolytic effects of MMP-10 and rivaroxaban were evaluated by thromboelastometry and thrombin-activatable fibrinolysis inhibitor (TAFI) activation assays.

RESULTS

Only PCC reduced haemorrhage volume and improved functional outcome in warfarin-ICH, but both, PCC and CM-352 treatments, diminished haemorrhage volume (46%, p<0.01 and 64%, p<0.001, respectively) and ameliorated functional outcome in rivaroxaban-ICH. We further demonstrated that CM-352, but not PCC decreased neutrophil infiltration in the haemorrhage area at 24h. The effect of CM-352 could be related to MMP-10 inhibition since Mmp10-/- mice showed lower haemorrhage volume, better neurological score, reduced IL-6 levels and neutrophil infiltration, and increased PAI-1 after experimental ICH. Finally, we found that CM-352 reduced MMP-10 and rivaroxaban-related fibrinolytic effects in thromboelastometry and TAFI activation.

CONCLUSIONS

CM-352 treatment, by diminishing MMPs and rivaroxaban-associated fibrinolytic effects, might be a novel antihaemorrhagic strategy for rivaroxaban-associated ICH.

Molecular and Cellular Mechanisms of Delayed Fracture Healing in Mmp10 (Stromelysin 2) Knockout Mice

The remodeling of the extracellular matrix is a central function in endochondral ossification and bone homeostasis. During secondary fracture healing, vascular invasion and bone growth requires the removal of the cartilage intermediate and the coordinate action of the collagenase matrix metalloproteinase (MMP)-13, produced by hypertrophic chondrocytes, and the gelatinase MMP-9, produced by cells of hematopoietic lineage. Interfering with these MMP activities results in impaired fracture healing characterized by cartilage accumulation and delayed vascularization. MMP-10, Stromelysin 2, a matrix metalloproteinase with high homology to MMP-3 (Stromelysin 1), presents a wide range of putative substrates identified in vitro, but its targets and functions in vivo and especially during fracture healing and bone homeostasis are not well defined. Here, we investigated the role of MMP-10 through bone regeneration in C57BL/6 mice. During secondary fracture healing, MMP-10 is expressed by hematopoietic cells and its maximum expression peak is associated with cartilage resorption at 14 days post fracture (dpf). In accordance with this expression pattern, when Mmp10 is globally silenced, we observed an impaired fracture-healing phenotype at 14 dpf, characterized by delayed cartilage resorption and TRAP-positive cell accumulation. This phenotype can be rescued by a non-competitive transplant of wild-type bone marrow, indicating that MMP-10 functions are required only in cells of hematopoietic linage. In addition, we found that this phenotype is a consequence of reduced gelatinase activity and the lack of proMMP-9 processing in macrophages. Our data provide evidence of the in vivo function of MMP-10 during endochondral ossification and defines the macrophages as the lead cell population in cartilage removal and vascular invasion. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

MMP-10 rs17435959 Polymorphism is Associated with the Formation and Stability of Carotid Atherosclerosis Plaque: A Case-Control Study

BACKGROUND

Matrix metalloproteinase 10 (MMP-10) has a close relationship with carotid atherosclerosis (CAS) and cerebral infarction. The MMP-10 rs17435959 polymorphism causes a leucine to valine transition at codon 4 in exon 1 of the MMP-10 gene and may have functional effects.

OBJECTIVES

To investigate the relationship between the MMP-10 rs17435959 polymorphism and the formation and stability of CAS plaques.

MATERIALS AND METHODS

The present case-control study contains 738 visitors who came to our health examination center for the first time. According to the carotid ultrasound examinations, visitors were classified into the vulnerable plaque group (41-86 years old, 141 male, 105 female), the stable plaque group (41-86 years old, 141 male, 105 female) and the no plaque group (41-85 years old, 141 male, 105 female). All visitors in the three groups were sex- and- age-matched, and cardiovascular and cerebrovascular diseases were absent. The polymorphism was genotyped by real-time polymerase chain reaction- restriction.

RESULTS

Compared to the GG genotype, the frequency of the CC and CG genotypes was significantly more common in the vulnerable plaque group than in the no plaque group (18.7% vs. 7.7%, unadjusted P = 0.002). Moreover, compared to the G allele, the frequency of the C allele was significantly more common in the vulnerable plaque group than in the no plaque group (10.4% vs. 3.9%, unadjusted P = 0.000) and in the vulnerable plaque group than in the stable plaque group (10.4% vs. 5.1%, unadjusted P = 0.008). Binary logistic regression showed that the CC and CG genotype was independent risk factor for the formation (P = 0.019, OR = 1.961, 95% CI [1.117, 3.444]) and vulnerability (P = 0.035, OR = 1.842, 95% CI [1.045, 3.247]) of CAS plaques. Moreover, individuals who have the C allele showed a higher level of fibrinogen, which was an independent risk factor for the formation of CAS plaques (P = 0.000, OR = 2.425, 95% CI [1.475, 3.985]).

CONCLUSIONS

The rs17435959 polymorphism was associated with the formation and vulnerability of CAS plaques. Individuals who had variant-type MMP-10 showed higher levels of fibrinogen, which promoted the formation of CAS plaques.

Thrombolytic strategies for ischemic stroke in the thrombectomy era

Twenty-five years ago, intravenous thrombolysis has revolutionized the care of patients with acute ischemic stroke. Since 2015, randomized clinical trials have demonstrated that mechanical thrombectomy improves functional outcome in stroke patients over intravenous thrombolysis alone. More recently, three randomized clinical trials have suggested that mechanical thrombectomy alone is noninferior to a combined strategy with both intravenous thrombolysis and mechanical thrombectomy. In the present review, we will present the last clinical and preclinical studies on the use of thrombolysis in stroke patients in the modern thrombectomy era. At the cost of a potential increased risk of hemorrhagic transformation, thrombolysis may promote arterial recanalization before thrombectomy, improve the rate of successful recanalization after thrombectomy, and restore microcirculation patency downstream of the main thrombus. Besides, new thrombolytic strategies targeting tissue-type plasminogen activator resistant thrombi are being developed, which could strengthen the beneficial effects of thrombolysis without carrying additional pro-hemorrhagic effects. For instance, tenecteplase has shown improved rate of recanalization compared with tissue-type plasminogen activator (alteplase). Beyond fibrinolysis, DNA- and von Willebrand factor-targeted thrombolytic strategies have shown promising results in experimental models of ischemic stroke. New combined strategies, improved thrombolytics, and dedicated clinical trials in selected patients are eagerly awaited to further improve functional outcome in stroke.

The Bone Regeneration Capacity of BMP-2 + MMP-10 Loaded Scaffolds Depends on the Tissue Status

Biomaterials-mediated bone formation in osteoporosis (OP) is challenging as it requires tissue growth promotion and adequate mineralization. Based on our previous findings, the development of scaffolds combining bone morphogenetic protein 2 (BMP-2) and matrix metalloproteinase 10 (MMP-10) shows promise for OP management. To test our hypothesis, scaffolds containing BMP-2 + MMP-10 at variable ratios or BMP-2 + Alendronate (ALD) were prepared. Systems were characterized and tested in vitro on healthy and OP mesenchymal stem cells and in vivo bone formation was studied on healthy and OP animals. Therapeutic molecules were efficiently encapsulated into PLGA microspheres and embedded into chitosan foams. The use of PLGA (poly(lactic-co-glycolic acid)) microspheres as therapeutic molecule reservoirs allowed them to achieve an in vitro and in vivo controlled release. A beneficial effect on the alkaline phosphatase activity of non-OP cells was observed for both combinations when compared with BMP-2 alone. This effect was not detected on OP cells where all treatments promoted a similar increase in ALP activity compared with control. The in vivo results indicated a positive effect of the BMP-2 + MMP-10 combination at both of the doses tested on tissue repair for OP mice while it had the opposite effect on non-OP animals. This fact can be explained by the scaffold’s slow-release rate and degradation that could be beneficial for delayed bone regeneration conditions but had the reverse effect on healthy animals. Therefore, the development of adequate scaffolds for bone regeneration requires consideration of the tissue catabolic/anabolic balance to obtain biomaterials with degradation/release behaviors suited for the existing tissue status.

Inside the Thrombus: Association of Hemostatic Parameters With Outcomes in Large Vessel Stroke Patients

Background: Actual clinical management of ischemic stroke (IS) is based on restoring cerebral blood flow using tissue plasminogen activator (tPA) and/or endovascular treatment (EVT). Mechanical thrombectomy has permitted the analysis of thrombus structural and cellular classic components. Nevertheless, histological assessment of hemostatic parameters such as thrombin-activatable fibrinolysis inhibitor (TAFI) and matrix metalloproteinase 10 (MMP-10) remains unknown, although their presence could determine thrombus stability and its response to thrombolytic treatment, improving patient's outcome.

Methods: We collected thrombi (n = 45) from large vessel occlusion (LVO) stroke patients (n = 53) and performed a histological analysis of different hemostatic parameters [TAFI, MMP-10, von Willebrand factor (VWF), and fibrin] and cellular components (erythrocytes, leukocytes, macrophages, lymphocytes, and platelets). Additionally, we evaluated the association of these parameters with plasma levels of MMP-10, TAFI and VWF activity and recorded clinical variables.

Results: In this study, we report for the first time the presence of MMP-10 and TAFI in all thrombi collected from LVO patients. Both proteins were localized in regions of inflammatory cells, surrounded by erythrocyte and platelet-rich areas, and their content was significantly associated (r = 0.41, p < 0.01). Thrombus TAFI was lower in patients who died during the first 3 months after stroke onset [odds ratio (OR) (95%CI); 0.59 (0.36–0.98), p = 0.043]. Likewise, we observed that thrombus MMP-10 was inversely correlated with the amount of VWF (r = −0.30, p < 0.05). Besides, VWF was associated with the presence of leukocytes (r = 0.37, p < 0.05), platelets (r = 0.32, p < 0.05), and 3 months mortality [OR (95%CI); 4.5 (1.2–17.1), p = 0.029]. Finally, plasma levels of TAFI correlated with circulating and thrombus platelets, while plasma MMP-10 was associated with cardiovascular risk factors and functional dependence at 3 months.

Conclusions: The present study suggests that the composition and distribution of thrombus hemostatic components might have clinical impact by influencing the response to pharmacological and mechanical therapies as well as guiding the development of new therapeutic strategies.

Serum Protein Changes in Pediatric Sepsis Patients Identified With an Aptamer-Based Multiplexed Proteomic Approach

OBJECTIVES

Sepsis, a life-threatening organ dysfunction caused by a dysregulated host response to infection, is a leading cause of death and disability among children worldwide. Identifying sepsis in pediatric patients is difficult and can lead to treatment delay. Our objective was to assess the host proteomic response to infection utilizing an aptamer-based multiplexed proteomics approach to identify novel serum protein changes that might help distinguish between pediatric sepsis and infection-negative systemic inflammation and hence can potentially improve sensitivity and specificity of the diagnosis of sepsis over current clinical criteria approaches.

DESIGN

Retrospective, observational cohort study.

SETTING

PICU and cardiac ICU, Seattle Children's Hospital, Seattle, WA.

PATIENTS

A cohort of 40 children with clinically overt sepsis and 30 children immediately postcardiopulmonary bypass surgery (infection-negative systemic inflammation control subjects) was recruited. Children with sepsis had a confirmed or suspected infection, two or more systemic inflammatory response syndrome criteria, and at least cardiovascular and/or pulmonary organ dysfunction.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serum samples from 35 of the sepsis and 28 of the bypass surgery subjects were available for screening with an aptamer-based proteomic platform that measures 1,305 proteins to search for large-scale serum protein expression pattern changes in sepsis. A total of 111 proteins were significantly differentially expressed between the sepsis and control groups, using the linear models for microarray data (linear modeling) and Boruta (decision trees) R packages, with 55 being previously identified in sepsis patients. Weighted gene correlation network analysis helped identify 76 proteins that correlated highly with clinical sepsis traits, 27 of which had not been previously reported in sepsis.

CONCLUSIONS

The serum protein changes identified with the aptamer-based multiplexed proteomics approach used in this study can be useful to distinguish between sepsis and noninfectious systemic inflammation.

Neuroinflammation and fibrosis in stroke: The good, the bad and the ugly

Stroke is the leading cause of death and the main cause of disability in surviving patients. The detrimental interaction between immune cells, glial cells, and matrix components in stroke pathology results in persistent inflammation that progresses to fibrosis. A substantial effort is being directed toward understanding the exact neuroinflammatory events that take place as a result of stroke. The initiation of a potent cytokine response, along with immune cell activation and infiltration in the ischemic core, has massive acute deleterious effects, generally exacerbated by comorbid inflammatory conditions. There is secondary neuroinflammation that promotes further injury, resulting in cell death, but conversely plays a beneficial role, by promoting recovery. This highlights the need for a better understanding of the neuroinflammatory and fibrotic processes, as well as the need to identify new mechanisms and potential modulators. In this review, we summarize several aspects of stroke-induced inflammation, fibrosis, and include a discussion of cytokine inhibitors/inducers, immune cells, and fibro-inflammation signaling inhibitors in order to identify new pharmacological means of intervention.

A Role for MMP-10 (Matrix Metalloproteinase-10) in Calcific Aortic Valve Stenosis

OBJECTIVE

Aortic valve (AV) calcification plays an important role in the progression of aortic stenosis (AS). MMP-10 (matrix metalloproteinase-10 or stromelysin-2) is involved in vascular calcification in atherosclerosis. We hypothesize that MMP-10 may play a pathophysiological role in calcific AS. Approach and Results: Blood samples (n=112 AS and n=349 controls) and AVs (n=88) from patients undergoing valve replacement were analyzed. Circulating MMP-10 was higher in patients with AS compared with controls (P<0.001) and correlated with TNFα (tumor necrosis factor α; r_S=0.451; P<0.0001). MMP-10 was detected by immunochemistry in AVs from patients with AS colocalized with aortic valve interstitial cells markers α-SMA (α-smooth muscle actin) and vimentin and with calcification markers Runx2 (Runt-related transcription factor 2) and SRY (sex-determining region Y)-box 9. MMP-10 expression in AVs was further confirmed by RT-qPCR and western blot. Ex vivo, MMP-10 was elevated in the conditioned media of AVs from patients with AS and associated with interleukin-1β (r_S=0.5045, P<0.001) and BMP (bone morphogenetic protein)-2 (r_S=0.5003, P<0.01). In vitro, recombinant human MMP-10 induced the overexpression of inflammatory, fibrotic, and osteogenic markers (interleukin-1β, α-SMA, vimentin, collagen, BMP-4, Sox9, OPN [osteopontin], BMP-9, and Smad 1/5/8; P<0.05) and cell mineralization in aortic valve interstitial cells isolated from human AVs, in a mechanism involving Akt (protein kinase B) phosphorylation. These effects were prevented by TIMP-1 (tissue inhibitor of metalloproteinases type 1), a physiological MMP inhibitor, or specifically by an anti-MMP-10 antibody.

CONCLUSIONS

MMP-10, which is overexpressed in aortic valve from patients with AS, seems to play a central role in calcification in AS through Akt phosphorylation. MMP-10 could be a new therapeutic target for delaying the progression of aortic valve calcification in AS.

Neuroinflammation: friend and foe for ischemic stroke

Stroke, the third leading cause of death and disability worldwide, is undergoing a change in perspective with the emergence of new ideas on neurodegeneration. The concept that stroke is a disorder solely of blood vessels has been expanded to include the effects of a detrimental interaction between glia, neurons, vascular cells, and matrix components, which is collectively referred to as the neurovascular unit. Following the acute stroke, the majority of which are ischemic, there is secondary neuroinflammation that both promotes further injury, resulting in cell death, but conversely plays a beneficial role, by promoting recovery. The proinflammatory signals from immune mediators rapidly activate resident cells and influence infiltration of a wide range of inflammatory cells (neutrophils, monocytes/macrophages, different subtypes of T cells, and other inflammatory cells) into the ischemic region exacerbating brain damage. In this review, we discuss how neuroinflammation has both beneficial as well as detrimental roles and recent therapeutic strategies to combat pathological responses. Here, we also focus on time-dependent entry of immune cells to the ischemic area and the impact of other pathological mediators, including oxidative stress, excitotoxicity, matrix metalloproteinases (MMPs), high-mobility group box 1 (HMGB1), arachidonic acid metabolites, mitogen-activated protein kinase (MAPK), and post-translational modifications that could potentially perpetuate ischemic brain damage after the acute injury. Understanding the time-dependent role of inflammatory factors could help in developing new diagnostic, prognostic, and therapeutic neuroprotective strategies for post-stroke inflammation.

Matrix Metalloproteinases in Renal Diseases: A Critical Appraisal

Matrix metalloproteinases (MMPs) are endopeptidases within the metzincin protein family that not only cleave extracellular matrix (ECM) components, but also process the non-ECM molecules, including various growth factors and their binding proteins. MMPs participate in cell to ECM interactions, and MMPs are known to be involved in cell proliferation mechanisms and most probably apoptosis. These proteinases are grouped into six classes: collagenases, gelatinases, stromelysins, matrilysins, membrane type MMPs, and other MMPs. Various mechanisms regulate the activity of MMPs, inhibition by tissue inhibitors of metalloproteinases being the most important. In the kidney, intrinsic glomerular cells and tubular epithelial cells synthesize several MMPs. The measurement of circulating MMPs can provide valuable information in patients with kidney diseases. They play an important role in many renal diseases, both acute and chronic. This review attempts to summarize the current knowledge of MMPs in the kidney and discusses recent data from patient and animal studies with reference to specific diseases. A better understanding of the MMPs' role in renal remodeling may open the way to new interventions favoring deleterious renal changes in a number of kidney diseases.

Combined sustained release of BMP2 and MMP10 accelerates bone formation and mineralization of calvaria critical size defect in mice

The effect of dual delivery of bone morphogenetic protein-2 (BMP-2) and matrix metalloproteinase 10 (MMP10) on bone regeneration was investigated in a murine model of calvarial critical-size defect, hypothesizing that it would result in an enhanced bone formation. Critical-size calvarial defects (4 mm diameter) were created in mice and PLGA microspheres preloaded with either BMP-2, MMP10 or a microsphere combination of both were transplanted into defect sites at different doses. Empty microspheres were used as the negative control. Encapsulation efficiency was assessed and in vivo release kinetics of BMP-2 and MMP10 were examined over 14 days. Histological analyses were used to analyze bone formation after four and eight weeks. Combination with MMP10 (30 ng) significantly enhanced BMP-2 (600 ng)-mediated osteogenesis, as confirmed by the increase in percentage of bone fill (p < .05) at four weeks. Moreover, it also increased mineral apposition rate (p < .05), measured by double labeling with tetracycline and calceine. MMP10 accelerates bone repair by enhancing BMP-2-promoted bone healing and improving the mineralization rate. In conclusion combination of MMP10 and BMP-2 may become a promising strategy for repair and regeneration of bone defects.

MMP10 Promotes Efficient Thrombolysis After Ischemic Stroke in Mice with Induced Diabetes

Diabetes is an important risk factor for ischemic stroke (IS). Tissue-type plasminogen activator (tPA) has been associated with less successful revascularization and poor functional outcome in diabetes. We assessed whether a new thrombolytic strategy based on MMP10 was more effective than tPA in a murine IS model of streptozotocin (STZ)-induced diabetes. Wild-type mice were administered a single dose of streptozotocin (STZ) (180 mg/kg) to develop STZ-induced diabetes mellitus. Two weeks later, IS was induced by thrombin injection into the middle cerebral artery and the effect of recombinant MMP10 (6.5 μg/kg), tPA (10 mg/kg) or tPA/MMP10 on brain damage and functional outcome were analysed. Motor activity was assessed using the open field test. Additionally, we studied plasminogen activator inhibitor-1 (PAI-1) and thrombin-antithrombin complex levels (TAT) by ELISA and oxidative stress and blood-brain barrier (BBB) integrity by immunohistochemistry and western blot. MMP10 treatment was more effective at reducing infarct size and neurodegeneration than tPA 24 h and 3 days after IS in diabetic mice. Locomotor activity was impaired by hyperglycemia and ischemic injury, but not by the thrombolytic treatments. Additionally, TAT, oxidative stress and BBB permeability were reduced by MMP10 treatment, whereas brain bleeding or PAI-1 expression did not differ between treatments. Thrombolytic treatment with MMP10 was more effective than tPA at reducing stroke and neurodegeneration in a diabetic murine model of IS, without increasing haemorrhage. Thus, we propose MMP10 as a potential candidate for the clinical treatment of IS in diabetic patients.

New thrombolytic strategy providing neuroprotection in experimental ischemic stroke: MMP10 alone or in combination with tissue-type plasminogen activator

Aims

Early reperfusion with tissue-type plasminogen activator (tPA) is an effective therapeutic strategy to treat acute ischemic stroke, but only 1/3 of tPA-treated patients recover and are free from disability. tPA has also shown neurotoxicity in experimental models of cerebral ischemia. Considering that MMP-10 improves stroke injury, we have examined the therapeutic and protective effect of MMP10 and tPA/MMP10 as clot-dissolving and neuroprotective agent in an experimental model of ischemic stroke and studied in vitro the molecular pathways involved in MMP10-mediated effects.

Methods and results

Cerebral ischemia was induced by the local injection of thrombin into the middle cerebral artery followed by reperfusion with MMP10 (6.5 µg/kg) and tPA (10 mg/kg) alone or in combination with MMP10. Cell cultures were also performed to determine the effect of MMP10 and tPA/MMP10 on brain endothelial cells and neurons. tPA/MMP10 significantly reduced the infarct size in the ischemic stroke model compared with tPA alone (P < 0.05). In vitro, MMP10 reduced the tPA-promoted endothelial ionic permeability, preserved the expression of claudin-5 and decreased ERK1/2 activation. Moreover, combination of tPA/MMP10 prevented tPA-mediated neuronal excitotoxicity and calcium influx. These effects were reversed by blocking MMP10 activity with a monoclonal antibody.

Conclusion

These results show that MMP10, either alone or in combination with tPA, might represent a new strategy for thrombolysis in ischemic stroke, providing higher protection against cerebrovascular damage.

Phenotypic Screening To Discover Novel Chemical Series as Efficient Antihemorrhagic Agents

In an effort to find novel chemical series as antifibrinolytic agents, we explore α-phenylsulfonyl-α-spiropiperidines bearing different zinc-binding groups (ZBGs) to target those metalloproteinases involved in the fibrinolytic process: MMP3 and MMP10. Surprisingly, all these new chemical series were inactive against these metalloproteinases; however, several new molecules retained the antifibrinolytic activity in a phenotypic functional assay using thromboelastometry and human whole blood. Further optimization led to compound 38 as a potent antifibrinolytic agent in vivo, three times more efficacious than the current standard-of-care (tranexamic acid, TXA) at 300 times lower dose. Finally, in order to decipher the underlying mode-of-action leading to this phenotypic response, an affinity-based probe 39 was successfully designed to identify the target involved in this response: a potentially unknown mechanism-of-action in the fibrinolytic process.

Post-stroke mRNA expression profile of MMPs: effect of genetic deletion of MMP-12

Background and purpose

Recent reports from our laboratory demonstrated the post-ischaemic expression profile of various matrix metalloproteinases (MMPs) in rats and the detrimental role of MMP-12 in post-stroke brain damage. We hypothesise that the post-stroke dysregulation of MMPs is similar across species and that genetic deletion of MMP-12 would not affect the post-stroke expression of other MMPs. We tested our hypothesis by determining the pre-ischaemic and post-ischaemic expression profile of MMPs in wild-type and MMP-12 knockout mice.

Methods

Focal cerebral ischaemia was induced in wild-type and MMP-12 knockout mice by middle cerebral artery occlusion procedure by insertion of a monofilament suture. One hour after ischaemia, reperfusion was initiated by removing the monofilament. One day after reperfusion, ischaemic brain tissues from various groups of mice were collected, and total RNA was isolated and subjected to cDNA synthesis followed by PCR analysis.

Results

Although the post-stroke expression profile of MMPs in the ischaemic brain of mice is different from rats, there is a clear species similarity in the expression of MMP-12, which was found to be predominantly upregulated in both species. Further, the post-stroke induction or inhibition of various MMPs in MMP-12 knockout mice is different from their respective expression profile in wild-type mice. Moreover, the brain mRNA expression profile of various MMPs in MMP-12 knockout mice under normal conditions is also different to their expression in wild-type mice.

Conclusions

In the ischaemic brain, MMP-12 upregulates several fold higher than any other MMP. Mice derived with the genetic deletion of MMP-12 are constitutive and have altered MMP expression profile both under normal and ischaemic conditions.

Temporal analysis of blood-brain barrier disruption and cerebrospinal fluid matrix metalloproteinases in rhesus monkeys subjected to transient ischemic stroke

Blood-brain barrier (BBB) disruption plays an important role in pathophysiological progress of ischemic stroke. However, our knowledge of the dynamic change of BBB permeability and its mechanism remains limited. In the current study, we used a non-human primate (NHP) MCAO model and a serial CSF sampling method that allowed us to determine the dynamic change of BBB permeability by calculating the CSF/serum albumin ratio (AR). We showed that AR increased rapidly and significantly after ischemia, and the fold increase of AR is highly correlated with the infarction size during the subacute phase. Moreover, we determined the temporal change of MMP-1, MMP-2, MMP-3, MMP-9, MMP-10, MMP-13, TIMP-1, and TIMP-2 in CSF and serum. Each MMP and TIMP showed different change patterns when comparing their values in CSF and serum. Based on the longitudinal dataset, we showed that the fold increase of MMP-9 in serum and CSF are both correlated to infarction size. Among the measured MMPs and TIMPs, only MMP-2, MMP-13, and TIMP-2 in CSF correlated with AR to some extent. Our data suggest there is no single MMP or TIMP fully responsible for BBB breakdown, which is regulated by a much more complicated signal network and further investigations of the mechanisms are needed.

CM352 Reduces Brain Damage and Improves Functional Recovery in a Rat Model of Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is an acute neurological disorder with high mortality and no effective treatment. In addition to the initial bleeding event, rebleeding and hematoma expansion are associated with poor outcome in these patients. We studied the effectiveness of the new antifibrinolytic agent CM352, a short-half-life matrix metalloproteinase inhibitor, for achieving early hemostasis and improving functional recovery in a rat model of collagenase-induced ICH.

METHODS AND RESULTS

ICH was induced by striatal injection of collagenase, and 1 hour later, rats received an intravenous injection of saline (n=6) or CM352 (1 mg/kg, n=6). Hematoma (basal and after 3 and 24 hours) and lesion (14 days) volumes were quantified on T2-weighted (T2) magnetic resonance images. Neurological and functional recovery was evaluated by using Bederson score and a cylinder test (basal, 24 hours, and 14 days). Early treatment (1 hour) with CM352 was efficient reducing hematoma expansion at 3 hours (P<0.01) and, more markedly, at 24 hours (P<0.01). Decreased bleeding after antifibrinolytic treatment was accompanied by reduced interleukin-6 levels at 3 hours (P<0.05) and smaller lesion volume at 14 days (P<0.01). CM352 drastically reduced sensorimotor impairment (cylinder test) after ICH in rats at 24 hours (P<0.01) and 14 days (P<0.01). Similarly, it also attenuated neurological deficit (Bederson scale) at 24 hours (P<0.01) and 14 days (P<0.01). Interestingly, late (3 hours) CM352 administration also resulted in reduced lesion size and better functional outcome.

CONCLUSIONS

CM352, a new antifibrinolytic agent and matrix metalloproteinase inhibitor, effectively prevented hematoma growth and reduced lesion size in ICH in association with improved functional and neurological recovery.

A pharmacogenomic profile of human neural progenitors undergoing differentiation in the presence of the traditional Chinese medicine NeuroAiD

NeuroAiD, a traditional Chinese medicine widely used to treat stroke patients in China, was recently demonstrated in rodent models and in clinical trials to possess neuroregenerative and neuroprotective properties. In order to understand the mechanisms employed by NeuroAiD to bring about its neuroproliferative and neuroprotective effects, we investigated the impact of MLC901, a reformulated version of MLC601, on human neural progenitors undergoing neural differentiation at the molecular level by performing three independent microarray experiments. Functional annotations of the genes regulated by MLC901 that were associated with neurogenesis were found to be enriched. We also identified potential targets (FGF19, GALR2, MMP10, FGF3 and TDO2) of MLC901 that could promote neurogenesis and neuroprotection in the human brain. This work highlighted some interesting targets and offered some insights into the possible mechanism of action of MLC901. The discovery could also provide a platform to the development of future therapeutic targets.

Implications of MMP9 for Blood Brain Barrier Disruption and Hemorrhagic Transformation Following Ischemic Stroke

Numerous studies have documented increases in matrix metalloproteinases (MMPs), specifically MMP-9 levels following stroke, with such perturbations associated with disruption of the blood brain barrier (BBB), increased risk of hemorrhagic complications, and worsened outcome. Despite this, controversy remains as to which cells release MMP-9 at the normal and pathological BBB, with even less clarity in the context of stroke. This may be further complicated by the influence of tissue plasminogen activator (tPA) treatment. The aim of the present review is to examine the relationship between neutrophils, MMP-9 and tPA following ischemic stroke to elucidate which cells are responsible for the increases in MMP-9 and resultant barrier changes and hemorrhage observed following stroke.

Association of matrix metalloproteinase-10 polymorphisms with susceptibility to pelvic organ prolapse

AIM

The aim of this study was to explore the correlation between genetic mutations in matrix metalloproteinase-10 (MMP-10) and susceptibility to pelvic organ prolapse (POP).

MATERIAL AND METHODS

From September 2011 to December 2013, 263 subjects were recruited, including 91 patients with POP (case group) and 172 non-POP patients (control group). Total MMP-10 concentrations in serum were measured by enzyme-linked immunosorbent assay. The genotyping of MMP-10 was achieved by quantitative real-time polymerase chain reaction. All data were analyzed with SPSS 18.0.

RESULTS

We found that parity, menopause, history of total hysterectomy, and family history of POP were all significantly higher in the POP group than in the control group (P = 0.017, P = 0.046, P = 0.0029 and P < 0.001, respectively). Serum MMP-10 levels were obviously higher in the POP group than in the control group (P < 0.05). In addition, there was a statistically significant difference between the two groups in the distribution frequency of the MMP-10 (rs17435959G/C) genotype (P < 0.05). However, the distribution frequency of the MMP-10 (rs17293607C/T) genotype between the two groups showed no significant differences (P > 0.05). Furthermore, the patients with parity > 2 and postmenopausal women had elevated serum MMP-10 levels, and the patients with parity > 2 and postmenopausal women who carried the G/C + C/C genotype in the MMP-10 gene had an increased risk of POP.

CONCLUSION

We support the view that the rs17435959 polymorphism of the MMP-10 gene may be associated with an increased risk of POP.

Activated protein C β-glycoform promotes enhanced noncanonical PAR1 proteolysis and superior resistance to ischemic injury

Activated protein C (APC) is an anticoagulant protease that initiates cell signaling via protease-activated receptor 1 (PAR1) to regulate vascular integrity and inflammatory response. In this study, a recombinant APC variant (APC(N329Q)) mimicking the naturally occurring APC-β plasma glycoform was found to exhibit superior PAR1 proteolysis at a cleavage site that selectively mediates cytoprotective signaling. APC(N329Q) also enhanced integrin αMβ2-dependent PAR1 proteolysis to exert significantly improved antiinflammatory activity on macrophages compared with wild-type APC. Recent therapeutic applications of recombinant APC in ischemic stroke models have used APC variants with limited anticoagulant activity to negate potential bleeding side effects. Using a mouse model of ischemic stroke and late t-PA intervention, the neuroprotective activity of a murine APC variant with limited anticoagulant activity (mAPC(PS)) was compared with an identical APC variant except for the absence of glycosylation at the APC-β sequon (mAPC(PS/N329Q)). Remarkably, mAPC(PS/N329Q) limited cerebral ischemic injury and reduced brain lesion volume significantly more effectively than mAPC(PS). Collectively, this study reveals the importance of APC glycosylation in controlling the efficacy of PAR1 proteolysis by APC and demonstrates the potential of novel APC variants with superior cytoprotective signaling function as enhanced therapeutic agents for the treatment of ischemic stroke.

Lack of TAFI increases brain damage and microparticle generation after thrombolytic therapy in ischemic stroke

BACKGROUND

Thrombin-activatable fibrinolysis inhibitor (TAFI) plays an important role in coagulation and fibrinolysis. Whereas TAFI deficiency may lead to a haemorrhagic tendency, data from TAFI knockout mice (TAFI-/-) are controversial and no differences have been reported in these animals after ischemic stroke. There are also no data regarding the role of circulating microparticles (MPs) in TAFI-/-.

OBJECTIVES

to examine the effect of tPA on the rate of intracranial haemorrhage (ICH) and on MPs generated in a model of ischemic stroke in TAFI-/- mice.

METHODS

Thrombin was injected into the middle cerebral artery (MCA) to analyse the effect of tPA (10mg/Kg) on the infarct size and haemorrhage in the absence of TAFI. Immunofluorescence for Fluoro-Jade C was performed on frozen brain slides to analyse neuronal degeneration after ischemia. MPs were isolated from mouse blood and their concentrations calculated by flow cytometry.

RESULTS

Compared with saline, tPA significantly increased the infarct size in TAFI-/- mice (p<0.05). Although plasma fibrinolytic activity (fibrin plate assay) was higher in these animals, no macroscopic or microscopic ICH was detected. A positive signal for apoptosis and degenerating neurons was observed in the infarct area, being significantly higher in tPA treated TAFI-/- mice (p<0.05). Interestingly, higher numbers of MPs were found in TAFI-/- plasma as compared to wild type, after stroke (p<0.05).

CONCLUSIONS

TAFI deficiency results in increased brain damage in a model of thrombolysis after ischemic stroke, which was not associated with bleeding but with neuronal degeneration and MP production.

Increased expression of angiogenic and inflammatory proteins in the vitreous of patients with ischemic central retinal vein occlusion

Background

Central retinal vein occlusion (CRVO) is a common disease characterized by a disrupted retinal blood supply and a high risk of subsequent vision loss due to retinal edema and neovascular disease. This study was designed to assess the concentrations of selected signaling proteins in the vitreous and blood of patients with ischemic CRVO.

Methods

Vitreous and blood samples were collected from patients undergoing surgery for ischemic CRVO (radial optic neurotomy (RON), n = 13), epiretinal gliosis or macular hole (control group, n = 13). Concentrations of 40 different proteins were determined by an ELISA-type antibody microarray.

Results

Expression of proteins enriched in the vitreous (CCL2, IGFBP2, MMP10, HGF, TNFRSF11B (OPG)) was localized by immunohistochemistry in eyes of patients with severe ischemic CRVO followed by secondary glaucoma. Vitreal expression levels were higher in CRVO patients than in the control group (CRVO / control; p < 0.05) for ADIPOQ (13.6), ANGPT2 (20.5), CCL2 (MCP1) (3.2), HGF (4.7), IFNG (13.9), IGFBP1 (14.7), IGFBP2 (1.8), IGFBP3 (4.1), IGFBP4 (1.7), IL6 (10.8), LEP (3.4), MMP3 (4.3), MMP9 (3.6), MMP10 (5.4), PPBP (CXCL7 or NAP2) (11.8), TIMP4 (3.8), and VEGFA (85.3). In CRVO patients, vitreal levels of CCL2 (4.2), HGF (23.3), IGFBP2 (1.23), MMP10 (2.47), TNFRSF11B (2.96), and VEGFA (29.2) were higher than the blood levels (vitreous / blood, p < 0.05). Expression of CCL2, IGFBP2, MMP10, HGF, and TNFRSF11B was preferentially localized to the retina and the retinal pigment epithelium (RPE).

Conclusion

Proteins related to hypoxia, angiogenesis, and inflammation were significantly elevated in the vitreous of CRVO patients. Moreover, some markers known to indicate atherosclerosis may be related to a basic vascular disease underlying RVO. This would imply that local therapeutic targeting might not be sufficient for a long term therapy in a systemic disease but hypothetically reduce local changes as an initial therapeutic approach.

Discovery and safety profiling of a potent preclinical candidate, (4-[4-[[(3R)-3-(hydroxycarbamoyl)-8-azaspiro[4.5]decan-3-yl]sulfonyl]phenoxy]-N-methylbenzamide) (CM-352), for the prevention and treatment of hemorrhage

Discovery of potent and safe therapeutics that improve upon currently available antifibrinolytics, e.g., tranexamic acid (TXA, 1) and aprotinin, has been challenging. Matrix metalloproteinases (MMPs) participate in thrombus dissolution. Then we designed a novel series of optimized MMP inhibitors that went through phenotypic screening consisting of thromboelastometry and mouse tail bleeding. Our optimized lead compound, CM-352 (2), inhibited fibrinolysis in human whole blood functional assays and was more effective than the current standard of care, 1, in the tail-bleeding model using a 30 000 times lower dose. Moreover, 2 reduced blood loss during liver hepatectomy, while 1 and aprotinin had no effect. Molecule 2 displayed optimal pharmacokinetic and safety profiles with no evidence of thrombosis or coagulation impairment. This novel mechanism of action, targeting MMP, defines a new class of antihemorrhagic agents without interfering with normal hemostatic function. Furthermore, 2 represents a preclinical candidate for the acute treatment of bleeding.

Compartment-specific expression of collagens and their processing enzymes in intrapulmonary arteries of IPAH patients

Alterations in extracellular matrix (ECM) have been implicated in the pathophysiology of pulmonary hypertension. Here, we have undertaken a compartment-specific study to elucidate the expression profile of collagens and their processing enzymes in donor and idiopathic pulmonary arterial hypertension (IPAH) pulmonary arteries. Predominant intimal, but also medial and perivascular, remodeling and reduced lumen diameter were detected in IPAH pulmonary arteries. Two-photon microscopy demonstrated accumulation of collagen fibers. Quantification of collagen in pulmonary arteries revealed collagen accumulation mainly in the intima of IPAH pulmonary arteries compared with donors. Laser capture-microdissected pulmonary artery profiles (intima+media and perivascular tissue) were analyzed by real-time PCR for ECM gene expression. In the intima+media of IPAH vessels, collagens (COL4A5, COL14A1, and COL18A1), matrix metalloproteinase (MMP) 19, and a disintegrin and metalloprotease (ADAM) 33 were higher expressed, whereas MMP10, ADAM17, TIMP1, and TIMP3 were less abundant. Localization of COLXVIII, its cleavage product endostatin, and MMP10, ADAM33, and TIMP1 was confirmed in pulmonary arteries by immunohistochemistry. ELISA for collagen XVIII/endostatin demonstrated significantly elevated plasma levels in IPAH patients compared with donors, whereas circulating MMP10, ADAM33, and TIMP1 levels were similar between the two groups. Endostatin levels were correlated with pulmonary arterial wedge pressure, and established prognostic markers of IPAH, right atrial pressure, cardiac index, 6-min walking distance, NH2-terminal pro-brain natriuretic peptide, and uric acid. Expression of unstudied collagens, MMPs, ADAMs, and TIMPs were found to be significantly altered in IPAH intima+media. Elevated levels of circulating collagen XVIII/endostatin are associated with markers of a poor prognosis.

Matrix metalloproteinases in atherosclerosis: role of nitric oxide, hydrogen sulfide, homocysteine, and polymorphisms

Atherosclerosis is an inflammatory process that involves activation of matrix metalloproteinases (MMPs); MMPs degrade collagen and allow for smooth-muscle cell migration within a vessel. Moreover, this begets an accumulation of other cellular material, resulting in occlusion of the vessel and ischemic events to tissues in need of nutrients. Homocysteine has been shown to activate MMPs via an increase in oxidative stress and acting as a signaling molecule on receptors like the peroxisome proliferator activated receptor-γ and N-methyl-D-aspartate receptor. Nitric oxide has been shown to be beneficial in some cases of deactivating MMPs. However, in other cases, it has been shown to be harmful. Further studies are warranted on the scenarios that are beneficial versus destructive. Hydrogen sulfide (H₂S) has been shown to decrease MMP activities in all cases in the literature by acting as an antioxidant and vasodilator. Various MMP-knockout and gene-silencing models have been used to determine the function of the many different MMPs. This has allowed us to discern the role that each MMP has in promoting or alleviating pathological conditions. Furthermore, there has been some study into the MMP polymorphisms that exist in the population. The purpose of this review is to examine the role of MMPs and their polymorphisms on the development of atherosclerosis, with emphasis placed on pathways that involve nitric oxide, hydrogen sulfide, and homocysteine.

Design, synthesis, and biological evaluation of novel matrix metalloproteinase inhibitors as potent antihemorrhagic agents: from hit identification to an optimized lead

Growing evidence suggests that matrix metalloproteinases (MMP) are involved in thrombus dissolution; then, considering that new therapeutic strategies are required for controlling hemorrhage, we hypothesized that MMP inhibition may reduce bleeding by delaying fibrinolysis. Thus, we designed and synthesized a novel series of MMP inhibitors to identify potential candidates for acute treatment of bleeding. Structure-based and knowledge-based strategies were utilized to design this novel chemical series, α-spiropiperidine hydroxamates, of potent and soluble (>75 μg/mL) pan-MMP inhibitors. The initial hit, 12, was progressed to an optimal lead 19d. Racemic 19d showed a remarkable in vitro phenotypic response and outstanding in vivo efficacy; in fact, the mouse bleeding time at 1 mg/kg was 0.85 min compared to 29.28 min using saline. In addition, 19d displayed an optimal ADME and safety profile (e.g., no thrombus formation). Its corresponding enantiomers were separated, leading to the preclinical candidate 5 (described in Drug Annotations series, J. Med. Chem. 2015, ).

Cystamine improves functional recovery via axon remodeling and neuroprotection after stroke in mice

AIMS

Stroke is a leading cause of disability. However, there is no pharmacological therapy available for promoting recovery. Although treatment of stroke with cystamine has gained increasing interest, the detailed mechanisms underlying this process remain elusive. Thus, our aim is to examine the effect of cystamine on the function recovery after stroke and investigate further cystamine mechanisms.

METHODS

Adult male C57BL/6J mice were subjected to photothrombotic model of focal stroke or sham operation. Cystamine or saline was administered intraperitoneally at 24 h after stroke. Functional recovery was analyzed using behavioral tests; axon remodeling was analyzed using magnetic resonance diffusion tensor imaging (DTI) and histological assessment. ANA-12, an antagonist of tropomyosin-related kinase B (TrkB), was administrated to examine the mechanisms underlying the neuroprotection mediated by cystamine.

RESULTS

Treatment with cystamine resulted in amelioration of impaired function with concomitant enhancement of axonal remodeling. Cystamine treatment significantly increased brain-derived neurotrophic factor (BDNF) levels and phosphorylation of TrkB in brain after stroke. Cystamine significantly enhanced neuronal progenitor cell proliferation, neuronal survival, and plasticity through BDNF/TrkB pathway.

CONCLUSIONS

These data provide evidence to investigate the promising utility of cystamine for therapy of stroke in a variety of ways, acting principally through BDNF/TrkB pathway.

Functional MMP-10 is required for efficient tissue repair after experimental hind limb ischemia

We studied the role of matrix metalloproteinase-10 (MMP-10) during skeletal muscle repair after ischemia using a model of femoral artery excision in wild-type (WT) and MMP-10 deficient (Mmp10(-/-)) mice. Functional changes were analyzed by small animal positron emission tomography and tissue morphology by immunohistochemistry. Gene expression and protein analysis were used to study the molecular mechanisms governed by MMP-10 in hypoxia. Early after ischemia, MMP-10 deficiency resulted in delayed tissue reperfusion (10%, P < 0.01) and in increased necrosis (2-fold, P < 0.01), neutrophil (4-fold, P < 0.01), and macrophage (1.5-fold, P < 0.01) infiltration. These differences at early time points resulted in delayed myotube regeneration in Mmp10(-/-) soleus at later stages (regenerating myofibers: 30 ± 9% WT vs. 68 ± 10% Mmp10(-/-), P < 0.01). The injection of MMP-10 into Mmp10(-/-) mice rescued the observed phenotype. A molecular analysis revealed higher levels of Cxcl1 mRNA (10-fold, P < 0.05) and protein (30%) in the ischemic Mmp10(-/-) muscle resulting from a lack of transcriptional inhibition by MMP-10. This was further confirmed using siRNA against MMP-10 in vivo. Our results demonstrate an important role of MMP-10 for proper muscle repair after ischemia, and suggest that chemokine regulation such as Cxcl1 by MMP-10 is involved in muscle regeneration.

MMP-10 is required for efficient muscle regeneration in mouse models of injury and muscular dystrophy

Matrix metalloproteinases (MMPs), a family of endopeptidases that are involved in the degradation of extracellular matrix components, have been implicated in skeletal muscle regeneration. Among the MMPs, MMP-2 and MMP-9 are upregulated in Duchenne muscular dystrophy (DMD), a fatal X-linked muscle disorder. However, inhibition or overexpression of specific MMPs in a mouse model of DMD (mdx) has yielded mixed results regarding disease progression, depending on the MMP studied. Here, we have examined the role of MMP-10 in muscle regeneration during injury and muscular dystrophy. We found that skeletal muscle increases MMP-10 protein expression in response to damage (notexin) or disease (mdx mice), suggesting its role in muscle regeneration. In addition, we found that MMP-10-deficient muscles displayed impaired recruitment of endothelial cells, reduced levels of extracellular matrix proteins, diminished collagen deposition, and decreased fiber size, which collectively contributed to delayed muscle regeneration after injury. Also, MMP-10 knockout in mdx mice led to a deteriorated dystrophic phenotype. Moreover, MMP-10 mRNA silencing in injured muscles (wild-type and mdx) reduced muscle regeneration, while addition of recombinant human MMP-10 accelerated muscle repair, suggesting that MMP-10 is required for efficient muscle regeneration. Furthermore, our data suggest that MMP-10-mediated muscle repair is associated with VEGF/Akt signaling. Thus, our findings indicate that MMP-10 is critical for skeletal muscle maintenance and regeneration during injury and disease.

Matrix metalloproteinase-10 expression is induced during hepatic injury and plays a fundamental role in liver tissue repair

BACKGROUND & AIMS

Upon tissue injury, the liver mounts a potent reparative and regenerative response. A role for proteases, including serine and matrix metalloproteinases (MMPs), in this process is increasingly recognized. We have evaluated the expression and function of MMP10 (stromelysin-2) in liver wound healing and regeneration.

METHODS

The hepatic expression of MMP10 was examined in two murine models: liver regeneration after two-thirds partial hepatectomy (PH) and bile duct ligation (BDL). MMP10 was detected in liver tissues by qPCR, western blotting and immunohistochemistry. The effect of growth factors and toll-like receptor 4 (TLR4) agonists on MMP10 expression was studied in cultured parenchymal and biliary epithelial cells and macrophages respectively. The role of MMP10 was evaluated by comparing the response of Mmp10+/+ and Mmp10-/- mice to PH and BDL. The intrahepatic turnover of the extracellular matrix proteins fibrin (ogen) and fibronectin was examined.

RESULTS

MMP10 mRNA was readily induced after PH and BDL. MMP10 protein was detected in hepatocytes, cholangiocytes and macrophages. In cultured liver epithelial cells, MMP10 expression was additively induced by transforming growth factor-β and epidermal growth factor receptor ligands. TLR4 ligands also stimulated MMP10 expression in macrophages. Lack of MMP10 resulted in increased liver injury upon PH and BDL. Resolution of necrotic areas was impaired, and Mmp10-/- mice showed increased fibrogenesis and defective turnover of fibrin (ogen) and fibronectin.

CONCLUSIONS

MMP10 expression is induced during mouse liver injury and participates in the hepatic wound healing response. The profibrinolytic activity of MMP10 may be essential in this novel hepatoprotective role.

Genetic variations within metalloproteinases impact on the prophylaxis of depressive phases in bipolar patients

BACKGROUND

The genetic background of the antidepressant response to pharmacological treatment in bipolar disorder (BD) remains elusive. This issue is of primary relevance in that the depressive phases of BD are difficult to treat and they are associated with suicide.

AIM

We investigated the role of a set of genetic variations (single-nucleotide polymorphisms) harbored by matrix metalloproteinases (MMPs) as predictors of response to treatment in depressed BD patients.

METHODS

654 BD patients from the publicly available Systematic Treatment Enhancement Program for Bipolar Disorder study were investigated. The outcome was the number of depressive events corrected by the number of times patients were assessed. Clinical and sociodemographic variables were tested as possible stratification factors and included in the analysis if necessary. Genetic predictors were 43 SNPs harbored by 17 MMPs. Imputation, quality check and pruning were conducted according to standards. RESULTS were corrected for multitesting.

RESULTS

rs486055 (MMP-10) was associated with the outcome. TT homozygotes had 5.08 ± 3.51 events, CT had 3.47 ± 3.18 and CC had 2.57 ± 2.96 depressive events corrected for the times they had been assessed. The time during which BD patients were observed was not significantly different between the rs486055 genotypes. We found evidence that MMP-10 may be a mediator of the number of depressive phases during BD. Due to the limits of the study including the small-to-medium sample size, the naturalistic design and the possible occurrence of false-positive findings, independent analyses are warranted.

Matrix metalloproteinase-10 plays an active role in microvascular complications in type 1 diabetic patients

AIMS/HYPOTHESIS

The role of metalloproteinase-10 (MMP-10) in type 1 diabetes is not known. We hypothesise that it plays a role in the onset and progression of diabetic nephropathy and retinopathy.

METHODS

Serum MMP-10 levels from 269 patients with type 1 diabetes were measured, and their association with microvascular complications was analysed. We also studied whether knocking out the Mmp10 gene influenced the extent of renal injury and retinal damage in a streptozotocin-induced diabetic mouse model.

RESULTS

The risk of nephropathy and proliferative retinopathy associated with the highest vs the lowest MMP-10 tertile was increased three to four times independently of the classical risk factors. Accordingly, renal function and morphology were better preserved in diabetic Mmp10 −⁄− mice than in their Mmp10 +/+ counterparts. There were more kidney-infiltrating macrophages in diabetic Mmp10+/+ mice, suggesting that MMP-10 contributes to the inflammatory response leading to microvascular complications. The loss of neuronal cells in the retinas of diabetic Mmp10 +/+ mice was higher than in Mmp10 −⁄− mice. Retinal inflammation was decreased in Mmp10 −⁄− mice, as indicated by their reduced retinal caspase-1 levels.

CONCLUSIONS/INTERPRETATION

MMP-10 is involved in the development of microvascular complications in type 1 diabetes and emerges as a potential therapeutic target for slowing down the evolution of diabetic nephropathy and retinopathy.

proMetalloproteinase-10 is associated with brain damage and clinical outcome in acute ischemic stroke

BACKGROUND

Matrix metalloproteinases (MMPs) mediate tissue injury during stroke but also neurovascular remodeling and we have shown that MMP-10 is involved in atherothrombosis.

OBJECTIVE

The purpose of this study was to examine the relationship between proMMP-10 and clinical outcome, assessing inflammatory and proteolytic markers, in patients with acute ischemic stroke.

METHODS

We prospectively studied 76 patients with ischemic stroke treated with tPA within the first 3 h from symptom onset, compared with 202 non-tPA-treated ischemic stroke patients and 83 asymptomatic subjects. Stroke severity was assessed with the National Institutes of Health Stroke Scale (NIHSS). Hemorrhagic transformation (HT) and severe brain edema were diagnosed by cranial CT. Good functional outcome was defined as a modified Rankin scale score ≤ 2 at 90 days. Serum levels of MMP-9, proMMP-10, TIMP-1, tumor necrosis factor-α (TNFα), interleukin-6 and cellular fibronectin were measured at admission. The effect of TNFα on endothelial proMMP-10 was assessed in vitro.

RESULTS

Serum proMMP-10 concentration in ischemic stroke patients, non-treated or treated with t-PA, which was higher than age-matched healthy subjects (P < 0.0001), was independently associated with higher infarct volume, severe brain edema, neurological deterioration and poor functional outcome at 3 months (all P < 0.05), but not with HT. proMMP-10 levels were also independently and positively associated with circulating levels of TNFα (P < 0.0001), which induced its endothelial expression in vitro, both mRNA and protein. MMP-9, however, was only associated with HT and severe edema (all P < 0.05).

CONCLUSIONS

Increased serum proMMP-10 after acute ischemic stroke, associated with TNFα, is a new marker of brain damage and poor outcome.

Matrix metalloproteinases and blood-brain barrier disruption in acute ischemic stroke

Ischemic stroke continues to be one of the most challenging diseases in translational neurology. Tissue plasminogen activator (tPA) remains the only approved treatment for acute ischemic stroke, but its use is limited to the first hours after stroke onset due to an increased risk of hemorrhagic transformation over time resulting in enhanced brain injury. In this review we discuss the role of matrix metalloproteinases (MMPs) in blood-brain barrier (BBB) disruption as a consequence of ischemic stroke. MMP-9 in particular appears to play an important role in tPA-associated hemorrhagic complications. Reactive oxygen species can enhance the effects of tPA on MMP activation through the loss of caveolin-1 (cav-1), a protein encoded in the cav-1 gene that serves as a critical determinant of BBB permeability. This review provides an overview of MMPs' role in BBB breakdown during acute ischemic stroke. The possible role of MMPs in combination treatment of acute ischemic stroke is also examined.

Inflammation in atherosclerosis: a cause or a result of vascular disorders?

Sound data support the concept that in atherosclerosis, inflammation and dyslipidemia intersect each other and that irrespective of the initiator, both participate from the early stages to the ultimate fate of the atheromatous plaque. The two partakers manoeuvre a vicious circle in atheroma formation: dyslipidaemia triggers an inflammatory process and inflammation elicits dyslipidaemia. Independent of the initial cause, the atherosclerotic lesions occur focally, in particular arterial-susceptible sites, by a process that, although continuous, can be arbitrarily divided into a sequence of consecutive stages that lead from fatty streak to the fibro-lipid plaque and ultimately to plaque rupture and thrombosis. In the process, the initial event is a change in endothelial cells (EC) constitutive properties. Then, the molecular alarm signals send by dysfunctional EC are decoded by specific blood immune cells (monocytes, T lymphocytes, neutrophils, mast cells) and by the resident vascular cells, that respond by initiating a robust inflammatory process, in which the cells and the factors they secrete hasten the atheroma development. Direct and indirect crosstalk between the cells housed within the nascent plaque, complemented by the increase in risk factors of atherosclerosis lead to atheroma development and outcome. The initial inflammatory response can be regarded as a defense/protective reaction mechanism, but its further amplification, speeds up atherosclerosis. In this review, we provide an overview on the role of inflammation and dyslipidaemia and their intersection in atherogenesis. The data may add to the foundation of a novel attitude in the diagnosis and treatment of atherosclerosis.

Role of matrix metalloproteinase-10 in the BMP-2 inducing osteoblastic differentiation

Fibrodysplasia ossificans progressiva (FOP) is a skeletal disorder with progressive heterotopic ossification in skeletal muscle. A mutation causing constitutive activation in a bone morphogenetic protein (BMP) type 1 receptor [ALK2(R206H)] is found in most patients with FOP. However, the details in the heterotopic ossification of muscle in FOP and the role of matrix metalloproteinase-10 (MMP-10) in bone remain to be fully elucidated. In the present study, we investigated the role of MMP-10 in the differentiation of mouse myoblastic C2C12 cells into osteoblasts. MMP-10 was extracted as a factor, whose expression was most extensively enhanced by ALK2 (R206H) transfection in C2C12 cells. MMP-10 significantly augmented the levels of Osterix, type 1 collagen, alkaline phosphatase (ALP) and osteocalcin mRNA as well as ALP activity enhanced by BMP-2 in C2C12 cells. Moreover, a reduction in endogenous MMP-10 levels by siRNA significantly decreased the levels of Runx2, Osterix, type 1 collagen, ALP and osteocalcin mRNA enhanced by BMP-2 in these cells. In addition, MMP-10 increased the phosphorylation of Smad1/5/8 as well as enhanced the levels of Smad6 and Smad7 mRNA induced by BMP-2. In conclusion, the present study first demonstrated that MMP-10 promotes the differentiation of myoblasts into osteoblasts by interacting with the BMP signaling pathway. MMP-10 may play some important role in the heterotopic ossification of muscle in FOP.

Induction of oxidative stress by oxidized LDL via meprinα-activated epidermal growth factor receptor in macrophages

AIMS

The aim of this study was to explore meprinα-mediated transactivation of the epidermal growth factor receptor (EGFR) and reactive oxygen species (ROS) production in macrophages.

METHODS AND RESULTS

Accelerated atherosclerotic lesions were established by administration of a high-fat diet in apolipoprotein E-deficient (apoE(-/-)) mice. Lentiviral overexpression of meprinα in the thoracic aortic artery during plaque formation enhanced intra-plaque macrophage induction of ROS as well as formation of atherosclerotic plaques, whereas AG1478 (specific inhibitor of the EGFR) treatment exerted the opposite effect. A meprinα inhibitor abrogated EGFR activation in mice. In cultured J774a.1 macrophages, oxidized low-density lipoprotein (OxLDL) increased ROS formation and EGFR activation through a ligand [heparin-binding epidermal growth factor-like growth factor (HB-EGF)]-dependent pathway. However, a meprinα inhibitor or specific siRNA inhibited ROS production and EGFR activation. Recombinant mouse meprinα enhanced OxLDL-stimulated production of ROS and induced HB-EGF. Inhibition of p38 mitogen-activated protein kinase by SB203580 decreased OxLDL-stimulated production of ROS. Conversely, inhibition of meprinα or PI3K-Rac1 inhibitors also decreased p38 activity in OxLDL-stimulated macrophages. In addition, inhibition of meprinα reversed OxLDL-stimulated activation of PI3K.

CONCLUSION

Meprinα promotes OxLDL-induced plaque formation and ROS release by transactivation of the EGFR, followed by activation of the PI3K/Rac1/p38 pathway.

Matrix metalloproteinases in kidney homeostasis and diseases

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that have been increasingly linked to both normal physiology and abnormal pathology in the kidney. Collectively able to degrade all components of the extracellular matrix, MMPs were originally thought to antagonize the development of fibrotic diseases solely through digestion of excessive matrix. However, increasing evidence has shown that MMPs play a wide variety of roles in regulating inflammation, epithelial-mesenchymal transition, cell proliferation, angiogenesis, and apoptosis. We now have robust evidence for MMP dysregulation in a multitude of renal diseases including acute kidney injury, diabetic nephropathy, glomerulonephritis, inherited kidney disease, and chronic allograft nephropathy. The goal of this review is to summarize current findings regarding the role of MMPs in kidney diseases as well as the mechanisms of action of this family of proteases.

The mouse dorsal skinfold chamber as a model for the study of thrombolysis by intravital microscopy

Although intravital microscopy models of thrombosis in mice have contributed to dissect the mechanisms of thrombus formation and stability, they have not been well adapted to study long-term evolution of occlusive thrombi. Here, we assessed the suitability of the dorsal skinfold chamber (DSC) for the study of thrombolysis and testing of thrombolytic agents by intravital microscopy. We show that induction of FeCl3-induced occlusive thrombosis is achievable in microvessels of DSCs, and that thrombi formed in DSCs can be visualised by intravital microscopy using brightfield transmitted light, or fluorescent staining of thrombus components such as fibrinogen, platelets, leukocytes, and von Willebrand factor. Direct application of control saline or recombinant tissue-plasminogen activator (rtPA) to FeCl3-produced thrombi in DSCs did not affect thrombus size or induce recanalisation. However, in the presence of hirudin, rtPA treatment caused a rapid dose-dependent lysis of occlusive thrombi, resulting in recanalisation within 1 hour after treatment. Skin haemorrhage originating from vessels located inside and outside the FeCl3-injured area was also observed in DSCs of rtPA-treated mice. We further show that rtPA-induced thrombolysis was enhanced in plasminogen activator inhibitor-1-deficient (PAI-1-/-) mice, and dropped considerably as the time between occlusion and treatment application increased. Together, our results show that by allowing visualization and measurement of thrombus lysis and potential bleeding complications of thrombolytic treatments, the DSC provides a model for studying endogenous fibrinolysis and for first-line screening of thrombolytic agents. Furthermore, using this system, we found that thrombin and clot aging impair the thrombolytic action of rtPA towards FeCl3-produced thrombi.