Association between tPA therapy and raised early matrix metalloproteinase-9 in acute stroke

Blood protein biomarkers as diagnostic tool for ischemic stroke: a systematic review

AIM

This systematic review provides a summary of the blood protein biomarkers that have been studied for the diagnosis of acute ischemic stroke.

MATERIALS & METHODS

An extensive MEDLINE (using PubMed) and Web of Knowledge search was performed. From the 354 articles found, 42 were eligible for further analysis and 25 protein biomarkers were examined.

RESULTS

Though many candidate blood-based protein biomarkers were examined, only two could significantly differentiate ischemic stroke patients from healthy controls, stroke mimics and hemorrhagic stroke patients.

CONCLUSION

The blood protein biomarkers, brain natriuretic peptide (BNP) and S100B, were promising biomarkers in diagnosing ischemic stroke. They could be used in cases of diagnostic uncertainty and/or when less experienced healthcare personnel are involved.

Vessel Wall Enhancement and Blood–Cerebrospinal Fluid Barrier Disruption After Mechanical Thrombectomy in Acute Ischemic Stroke

Background and Purpose—

Less than half of acute ischemic stroke patients treated with mechanical thrombectomy obtain permanent clinical benefits. Consequently, there is an urgent need to identify mechanisms implicated in the limited efficacy of early reperfusion. We evaluated the predictors and prognostic significance of vessel wall permeability impairment and its association with blood–cerebrospinal fluid barrier (BCSFB) disruption after acute stroke treated with thrombectomy.

Methods—

A prospective cohort of acute stroke patients treated with stent retrievers was analyzed. Vessel wall permeability impairment was identified as gadolinium vessel wall enhancement (GVE) in a 24- to 48-hour follow-up contrast-enhanced magnetic resonance imaging, and severe BCSFB disruption was defined as subarachnoid hemorrhage or gadolinium sulcal enhancement (present across >10 slices). Infarct volume was evaluated in follow-up magnetic resonance imaging, and clinical outcome was evaluated with the modified Rankin Scale at day 90.

Results—

A total of 60 patients (median National Institutes of Health Stroke Scale score, 18) were analyzed, of whom 28 (47%) received intravenous alteplase before mechanical thrombectomy. Overall, 34 (57%) patients had GVE and 27 (45%) had severe BCSFB disruption. GVE was significantly associated with alteplase use before thrombectomy and with more stent retriever passes, along with the presence of severe BCSFB disruption. GVE was associated with poor clinical outcome, and both GVE and severe BCSFB disruption were associated with increased final infarct volume.

Conclusions—

These findings may support the clinical relevance of direct vessel damage and BCSFB disruption after acute stroke and reinforce the need for further improvements in reperfusion strategies. Further validation in larger cohorts of patients is warranted.

MMP-12 and TIMP Behavior in Symptomatic and Asymptomatic Critical Carotid Artery Stenosis

OBJECTIVE

The aim of this study was to evaluate the levels of matrix metalloproteinase-12 (MMP-12) and tissue inhibitors of metalloproteinases (TIMP)-1, TIMP-2, TIMP-3, and TIMP-4 in patients with symptomatic and asymptomatic critical carotid artery stenosis (CAS).

METHODS

We enrolled 10 patients affected by symptomatic CAS within 12 hours from onset of stroke (S group) and 30 patients with asymptomatic CAS (CAS group); 31 patients matched for age, sex, and traditional cardiovascular risk factors were used as controls (RF group). Serum levels of MMP-12, TIMP-1, TIMP-2, TIMP-3, and TIMP-4 were assessed by Luminex.

RESULTS

MMP-12 levels were significantly higher both in the S and CAS groups than in the RF group (P < .001). We found a significant decrease of all TIMPs in the CAS group compared with the RF group, whereas a significant increase was observed in the S group compared with the CAS group. A significant increase of TIMP-3 and TIMP-4 levels was observed in the S group compared with all other groups.

CONCLUSION

MMP-12 is related to critical CAS both symptomatic and asymptomatic, being mainly released in the late stage of plaque development. Moreover, we suggest that a specific pattern of matrix degrading enzyme inhibitors arises during the early phases of stroke.

Plasma kallikrein mediates brain hemorrhage and edema caused by tissue plasminogen activator therapy in mice after stroke

Thrombolytic therapy using tissue plasminogen activator (tPA) in acute stroke is associated with increased risks of cerebral hemorrhagic transformation and angioedema. Although plasma kallikrein (PKal) has been implicated in contributing to both hematoma expansion and thrombosis in stroke, its role in the complications associated with the therapeutic use of tPA in stroke is not yet available. We investigated the effects of tPA on plasma prekallikrein (PPK) activation and the role of PKal on cerebral outcomes in a murine thrombotic stroke model treated with tPA. We show that tPA increases PKal activity in vitro in both murine and human plasma, via a factor XII (FXII)-dependent mechanism. Intravenous administration of tPA increased circulating PKal activity in mice. In mice with thrombotic occlusion of the middle cerebral artery, tPA administration increased brain hemorrhage transformation, infarct volume, and edema. These adverse effects of tPA were ameliorated in PPK (Klkb1)-deficient and FXII-deficient mice and in wild-type (WT) mice pretreated with a PKal inhibitor prior to tPA. tPA-induced brain hemisphere reperfusion after photothrombolic middle cerebral artery occlusion was increased in Klkb1^-/- mice compared with WT mice. In addition, PKal inhibition reduced matrix metalloproteinase-9 activity in brain following stroke and tPA therapy. These data demonstrate that tPA activates PPK in plasma and PKal inhibition reduces cerebral complications associated with tPA-mediated thrombolysis in stroke.

Matrix Metalloproteinase-9 and Recovery of Acute Ischemic Stroke

BACKGROUND

Stroke outcome can be predicted by clinical features, biochemical parameters, and some risk factors. Matrix metalloproteinase-9 (MMP-9) is involved in various stages of stroke pathology. MMP-9 inhibitors are potential stroke therapeutic agents. Little is known about the relation between MMP-9-after the acute stage-and clinical recovery.

OBJECTIVE

The study aimed to investigate the serum level of MMP-9 at stroke onset as predictor of stroke outcome and the relation between the level of MMP-9 after 30 days and stroke recovery.

METHODS

The National Institutes of Health Stroke Scale, modified Rankin Scale, and serum level of MMP-9 were assessed in 30 patients with acute ischemic stroke during the first 24 hours of onset and then a month later. None of the patients received thrombolytic therapy. Thirty normal volunteers of matched age and sex were included in the control group.

RESULTS

The serum level of MMP-9 at stroke onset was independently positively correlated with stroke outcome. The serum level of MMP-9 30 days after stroke onset was positively correlated with initial stroke severity and outcome, as well as with clinical recovery.

CONCLUSION

Higher serum level of MMP-9 at stroke onset can be a predictor of poor stroke outcome. However, beyond the acute stage, MMP-9 may play beneficial role in stroke recovery.

The Role of Matrix Metalloproteinase Polymorphisms in Ischemic Stroke

Stroke remains the fifth leading cause of mortality in the United States with an annual rate of over 128,000 deaths per year. Differences in incidence, pathogenesis, and clinical outcome have long been noted when comparing ischemic stroke among different ethnicities. The observation that racial disparities exist in clinical outcomes after stroke has resulted in genetic studies focusing on specific polymorphisms. Some studies have focused on matrix metalloproteinases (MMPs). MMPs are a ubiquitous group of proteins with extensive roles that include extracellular matrix remodeling and blood-brain barrier disruption. MMPs play an important role in ischemic stroke pathophysiology and clinical outcome. This review will evaluate the evidence for associations between polymorphisms in MMP-1, 2, 3, 9, and 12 with ischemic stroke incidence, pathophysiology, and clinical outcome. The role of polymorphisms in MMP genes may influence the presentation of ischemic stroke and be influenced by racial and ethnic background. However, contradictory evidence for the role of MMP polymorphisms does exist in the literature, and further studies will be necessary to consolidate our understanding of these multi-faceted proteins.

Importance of perioperative management for emergency carotid artery stenting within 24h after intravenous thrombolysis for acute ischemic stroke: Case report

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We report a patient treated successfully via endovascular surgery within 24 h after intravenous thrombolysis using recombinant tissue plasminogen activator for acute cervical internal carotid artery occlusion.

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Emergency carotid artery stenting for the acute internal carotid artery occlusion may be considered a safe procedure in preventing early stroke recurrence in selected patients.

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When trying to perform emergency carotid artery stenting within 24 h after intravenous recombinant tissue plasminogen activator administration, several issues require attention, such as the decisions regarding the type of stent and embolic protection device, the selection of antiplatelet therapy and the methods of preventing hyper perfusion syndrome.

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We administered aspirin and clopidogrel for the prevention of subacute thrombosis, and we used dexmedetomidine for preventing hyperperfusion syndrome, so that we also obtained a good result.

Introduction

We report a patient treated successfully via endovascular surgery within 24 h after intravenous thrombolysis using recombinant tissue plasminogen activator for acute cervical internal carotid artery occlusion.

Presentation of case

A 68-year-old man was admitted to our hospital. Neurological examination revealed severe left-sided motor weakness. Magnetic resonance imaging showed no cerebral infarction, but magnetic resonance angiography revealed complete occlusion of the right internal carotid artery. Systemic intravenous injection of recombinant tissue plasminogen activator was performed within 4 h after the onset. But, magnetic resonance angiography still revealed complete occlusion. Revascularization of the right cervical internal carotid artery was performed via endovascular surgery. The occluded artery was successfully recanalized using the Penumbra System^® and stent placement at the origin of the internal carotid artery. Immediately after surgery, dual antiplatelet therapy (aspirin and clopidogrel) was initiated, and then cilostazol was added on the following day. Carotid ultrasonography and three-dimensional computed tomographic angiography at 14 days revealed no further obstruction to flow.

Discussion

When trying to perform emergency carotid artery stenting within 24 h after intravenous recombinant tissue plasminogen activator administration, several issues require attention, such as the decisions regarding the type of stent and embolic protection device, the selection of antiplatelet therapy and the methods of preventing hyperperfusion syndrome.

Conclusion

Emergency carotid artery stenting for the acute internal carotid artery occlusion may be considered a safe procedure in preventing early stroke recurrence in selected patients.

Preventive Ceftriaxone in Patients with Stroke Treated with Intravenous Thrombolysis: Post Hoc Analysis of the Preventive Antibiotics in Stroke Study

BACKGROUND

The Preventive Antibiotics in Stroke Study (PASS), a randomized open-label masked endpoint trial, showed that preventive ceftriaxone did not improve functional outcome at 3 months in patients with acute stroke (adjusted common OR 0.95; 95% CI 0.82-1.09). Post-hoc analyses showed that among patients who received intravenous thrombolysis (IVT), patients who received ceftriaxone had a significantly better outcome as compared with the control group. This study aimed to gain more insight into the characteristics of these patients.

METHODS

In PASS, 2,550 patients were randomly assigned to preventive antibiotic treatment with ceftriaxone or standard care. In current post-hoc analysis, 836 patients who received IVT were included. Primary outcome included functional status on the modified Rankin Scale, analyzed with adjusted ordinal regression. Secondary outcomes included infection rate and symptomatic intracerebral hemorrhage (sICH) rate.

RESULTS

For all patients in PASS, the p value for the interaction between IVT and preventive ceftriaxone regarding functional outcome was 0.03. Of the 836 IVT-treated patients, 437 were administered ceftriaxone and 399 were allocated to the control group. Baseline characteristics were similar. In the IVT subgroup, preventive ceftriaxone was associated with a significant reduction in unfavorable outcome (adjusted common OR 0.77; 95% CI 0.61-0.99; p = 0.04). Mortality at 3 months was similar (OR 0.75; 95% CI 0.48-1.18). Preventive ceftriaxone was associated with a reduction in infections (OR 0.43; 95% CI 0.28-0.66), and a trend towards an increased risk for sICH (OR 3.09; 95% CI 0.85-11.31). Timing of ceftriaxone administration did not influence the outcome (aOR 1.00; 95% CI 0.98-1.03; p = 0.85).

CONCLUSIONS

According to the post-hoc analysis of PASS, preventive ceftriaxone may improve the functional outcome in IVT-treated patients with acute stroke, despite a trend towards an increased rate of post-IVT-sICH.

Phytochemicals in Ischemic Stroke

Stroke is the second foremost cause of mortality worldwide and a major cause of long-term disability. Due to changes in lifestyle and an aging population, the incidence of stroke continues to increase and stroke mortality predicted to exceed 12 % by the year 2030. However, the development of pharmacological treatments for stroke has failed to progress much in over 20 years since the introduction of the thrombolytic drug, recombinant tissue plasminogen activator. These alarming circumstances caused many research groups to search for alternative treatments in the form of neuroprotectants. Here, we consider the potential use of phytochemicals in the treatment of stroke. Their historical use in traditional medicine and their excellent safety profile make phytochemicals attractive for the development of therapeutics in human diseases. Emerging findings suggest that some phytochemicals have the ability to target multiple pathophysiological processes involved in stroke including oxidative stress, inflammation and apoptotic cell death. Furthermore, epidemiological studies suggest that the consumption of plant sources rich in phytochemicals may reduce stroke risk, and so reinforce the possibility of developing preventative or neuroprotectant therapies for stroke. In this review, we describe results of preclinical studies that demonstrate beneficial effects of phytochemicals in experimental models relevant to stroke pathogenesis, and we consider their possible mechanisms of action.

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.

Intraarterial administration of norcantharidin attenuates ischemic stroke damage in rodents when given at the time of reperfusion: novel uses of endovascular capabilities

OBJECT Matrix metalloprotease-9 (MMP-9) plays a critical role in infarct progression, blood-brain barrier (BBB) disruption, and vasogenic edema. While systemic administration of MMP-9 inhibitors has shown neuroprotective promise in ischemic stroke, there has been little effort to incorporate these drugs into endovascular modalities. By modifying the rodent middle cerebral artery occlusion (MCAO) model to allow local intraarterial delivery of drugs, one has the ability to mimic endovascular delivery of therapeutics. Using this model, the authors sought to maximize the protective potential of MMP-9 inhibition by intraarterial administration of an MMP-9 inhibitor, norcantharidin (NCTD). METHODS Spontaneously hypertensive rats were subjected to 90-minute MCAO followed immediately by local intraarterial administration of NCTD. The rats' neurobehavioral performances were scored according to the ladder rung walking test results and the Garcia neurological test for as long as 7 days after stroke. MRI was also conducted 24 hours after the stroke to assess infarct volume and BBB disruption. At the end of the experimental protocol, rat brains were used for active MMP-9 immunohistochemical analysis to assess the degree of MMP-9 inhibition. RESULTS NCTD-treated rats showed significantly better neurobehavioral scores for all days tested. MR images also depicted significantly decreased infarct volumes and BBB disruption 24 hours after stroke. Inhibition of MMP-9 expression in the ischemic region was depicted on immunohistochemical analysis, wherein treated rats showed decreased active MMP-9 staining compared with controls. CONCLUSIONS Intraarterial NCTD significantly improved outcome when administered at the time of reperfusion in a spontaneously hypertensive rat stroke model. This study suggests that supplementing endovascular revascularization with local neuroprotective drug therapy may be a viable therapeutic strategy.

White Matter Injury After Subarachnoid Hemorrhage: Role of Blood-Brain Barrier Disruption and Matrix Metalloproteinase-9

BACKGROUND AND PURPOSE

We recently observed early white matter injury after experimental subarachnoid hemorrhage (SAH), but the underlying mechanisms are uncertain. This study investigated the potential role of matrix metalloproteinase (MMP)-9 in blood-brain barrier (BBB) disruption and consequent white matter injury.

METHODS

SAH was induced by endovascular perforation in adult male mice. The following 3 experiments were devised: (1) mice underwent magnetic resonance imaging at 24 h after SAH and were euthanized to determine BBB disruption and MMP-9 activation in white matter; (2) to investigate the role of MMP-9 in BBB disruption, lesion volumes on magnetic resonance imaging were compared between wild-type (WT) and MMP-9 knockout (MMP-9-/-) mice at 24 h after SAH; (3) WT and MMP-9-/- mice underwent magnetic resonance imaging at 1 and 8 days after SAH to detect time-dependent changes in brain injury. Brains were used to investigate myelin integrity in white matter.

RESULTS

In WT mice with SAH, white matter showed BBB disruption (albumin leakage) and T2 hyperintensity on magnetic resonance imaging. MMP-9 activity was elevated at 24 h after SAH. MMP-9-/- mice had less white matter T2 hyperintensity after SAH than WT mice. At 8 days after SAH, WT mice had decreased myelin integrity and MMP-9-/- mice developed less white matter injury.

CONCLUSIONS

SAH causes BBB disruption and consequent injury in white matter. MMP-9 plays an important role in those pathologies and could be a therapeutic target for SAH-induced white matter injury.

Proteinase 3 Induces Neuronal Cell Death Through Microglial Activation

Proteinase 3 (PR3) is released from neutrophil granules and is involved in the inflammatory process. PR3 is implicated in antimicrobial defense and cell death, but the exact role of PR3 in the brain is less defined. Microglia is the major immune effector cells in the CNS and is activated by brain injury. In the present study, the effect of PR3 on glial activation was investigated. Microglial activation was assessed by the intracellular level of reactive oxygen species and expression of inflammatory cytokines. The conditioned media from activated microglia by PR3 was used for measuring the neurotoxic effects of PR3-stimulated microglia. The effects of PR3 in vivo were measured by microinjecting PR3 into the rat brain. Herein we show that PR3 increased the inflammatory responses including the intracellular ROS and pro-inflammatory cytokine production in rat primary microglia. Conditioned media from PR3-treated microglia induced neuronal cell death in a concentration dependent manner. Furthermore, microinjected PR3 into the striatum of the rat brain induced microglial activation and neuronal cell death. Interestingly treatment with anti-PR3 monoclonal antibody and protease inhibitors ameliorated microglial activation induced by PR3 in primary microglia and striatum, which also prevented neuronal cell death in both conditions. The data presented here suggest that PR3 is a direct modulator of microglial activation and causes neuronal death through the augmentation of inflammatory responses. We suggest that PR3 could be a new modulator of neuroinflammation, and blocking PR3 would be a promising novel therapeutic target for neuroinflammatory disease such as stroke and Alzheimer's disease.

Targeting neutrophils in ischemic stroke: translational insights from experimental studies

Neutrophils have key roles in ischemic brain injury, thrombosis, and atherosclerosis. As such, neutrophils are of great interest as targets to treat and prevent ischemic stroke. After stroke, neutrophils respond rapidly promoting blood-brain barrier disruption, cerebral edema, and brain injury. A surge of neutrophil-derived reactive oxygen species, proteases, and cytokines are released as neutrophils interact with cerebral endothelium. Neutrophils also are linked to the major processes that cause ischemic stroke, thrombosis, and atherosclerosis. Thrombosis is promoted through interactions with platelets, clotting factors, and release of prothrombotic molecules. In atherosclerosis, neutrophils promote plaque formation and rupture by generating oxidized-low density lipoprotein, enhancing monocyte infiltration, and degrading the fibrous cap. In experimental studies targeting neutrophils can improve stroke. However, early human studies have been met with challenges, and suggest that selective targeting of neutrophils may be required. Several properties of neutrophil are beneficial and thus may important to preserve in patients with stroke including antimicrobial, antiinflammatory, and neuroprotective functions.

Treatment with recombinant tissue plasminogen activator (r-TPA) induces neutrophil degranulation in vitro via defined pathways

Thrombolysis is recommended for reperfusion following acute ischemic stroke (AIS), but its effects on stroke-associated injury remain to be clarified. Here, we investigated the effects of recombinant tissue plasminogen activator (r-tPA) on neutrophil pathophysiology in vitro and in a case-control study with AIS patients submitted (n=60) or not (n=30) to thrombolysis. Patients underwent radiological and clinical examination as well as blood sampling at admission and after 1, 7 and 90days. In vitro, 30-min incubation with 0.1-1 mg/ml r-tPA induced neutrophil degranulation in different substrate cultures. Pre-incubation with kinase inhibitors and Western blot documented that degranulation was associated with activation of PI3K/Akt and ERK1/2 pathways in Teflon dishes and PI3K/Akt in polystyrene. In thrombolysed patients, a peak of neutrophil degranulation products (matrix metalloproteinase [MMP]-9, MMP-8, neutrophil elastase and myeloperoxidase), was shown during the first hours from drug administration. This was accompanied by serum augmentation of protective tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. An increased rate of haemorrhagic transformations on day 1 after AIS was shown in thrombolysed patients as compared to non-thrombolysed controls. In conclusion, r-tPA treatment was associated with in vitro neutrophil degranulation, indicating these cells as potential determinants in early haemorrhagic complications after thrombolysis in AIS patients.

Glyburide is associated with attenuated vasogenic edema in stroke patients

BACKGROUND

Brain edema is a serious complication of ischemic stroke that can lead to secondary neurological deterioration and death. Glyburide is reported to prevent brain swelling in preclinical rodent models of ischemic stroke through inhibition of a non-selective channel composed of sulfonylurea receptor 1 and transient receptor potential cation channel subfamily M member 4. However, the relevance of this pathway to the development of cerebral edema in stroke patients is not known.

METHODS

Using a case-control design, we retrospectively assessed neuroimaging and blood markers of cytotoxic and vasogenic edema in subjects who were enrolled in the glyburide advantage in malignant edema and stroke-pilot (GAMES-Pilot) trial. We compared serial brain magnetic resonance images (MRIs) to a cohort with similar large volume infarctions. We also compared matrix metalloproteinase-9 (MMP-9) plasma level in large hemispheric stroke.

RESULTS

We report that IV glyburide was associated with T2 fluid-attenuated inversion recovery signal intensity ratio on brain MRI, diminished the lesional water diffusivity between days 1 and 2 (pseudo-normalization), and reduced blood MMP-9 level.

CONCLUSIONS

Several surrogate markers of vasogenic edema appear to be reduced in the setting of IV glyburide treatment in human stroke. Verification of these potential imaging and blood biomarkers is warranted in the context of a randomized, placebo-controlled trial.

Monitoring biomarkers of cellular injury and death in acute brain injury

BACKGROUND

Molecular biomarkers have revolutionalized diagnosis and treatment of many diseases, such as troponin use in myocardial infarction. Urgent need for high-fidelity biomarkers in neurocritical care has resulted in numerous studies reporting potential candidate biomarkers.

METHODS

We performed an electronic literature search and systematic review of English language articles on cellular/molecular biomarkers associated with outcome and with disease-specific secondary complications in adult patients with acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), traumatic brain injury (TBI), and post-cardiac arrest hypoxic ischemic encephalopathic injuries (HIE).

RESULTS

A total of 135 articles were included. Though a wide variety of potential biomarkers have been identified, only neuron-specific enolase has been validated in large cohorts and shows 100% specificity for poor outcome prediction in HIE patients not treated with therapeutic hypothermia. There are many promising candidate blood and CSF biomarkers in SAH, AIS, ICH, and TBI, but none yet meets criteria for routine clinical use.

CONCLUSION

Current studies vary significantly in patient selection, biosample collection/processing, and biomarker measurement protocols, thereby limiting the generalizability of overall results. Future large prospective studies with standardized treatment, biosample collection, and biomarker measurement and validation protocols are necessary to identify high-fidelity biomarkers in neurocritical care.

The effects of previous statin treatment on plasma matrix metalloproteinase-9 level in Chinese stroke patients undergoing thrombolysis

It is unclear whether previous statin therapy influences the prognosis, hemorrhagic transformation, and plasma matrix metalloproteinases (MMP)-9 levels in Chinese stroke patients receiving intravenous thrombolysis. We conduct a prospective cohort study of 193 patients treated with intravenous thrombolysis. All the enrolled patients were divided into 2 groups (the control group and the statin group), according to the previous history of statin use. The plasma MMP-9 levels were detected before and at 6 hours, 12 hours, 24 hours, and 72 hours after intravenous thrombolysis. The clinical outcome of stroke was measured in terms of the functional outcome and occurrence of symptomatic intracerebral hemorrhage. The MMP-9 levels increased after thrombolysis in statin group and control group. No significant intergroup difference was found in the MMP-9 levels before and at 6 hours after thrombolysis, but the levels were significantly lower in the statin group than in the control group at 12, 24, and 72 hours (P < .001) after thrombolysis. Similarly, no significant intergroup difference was noted in the occurrence of symptomatic intracranial hemorrhage as was the case with the modified Rankin scale (assessed by the Mann-Whitney U test) at 7 days (P = .428) and 90 days (P = .419) after thrombolysis. Our results indicate that pretreatment with statin can inhibit the thrombolysis-induced increase in plasma MMP-9 levels but does not significantly affect the prognosis of acute ischemic stroke patients undergoing intravenous thrombolysis.

Impact of the neutrophil response to granulocyte colony-stimulating factor on the risk of hemorrhage when used in combination with tissue plasminogen activator during the acute phase of experimental stroke

Background

Granulocyte colony-stimulating factor (G-CSF) is a pharmacologic agent inducing neutrophil mobilization and a new candidate for neuroprotection and neuroregeneration in stroke. Its effects when used in combination with tissue plasminogen activator (tPA) were explored during the acute phase of ischemic stroke.

Methods

We used a middle cerebral artery occlusion (MCAO) model of cerebral ischemia, associated with treatment with tPA, in male spontaneously hypertensive rats (SHR). Granulocyte colony-stimulating factor (G-CSF; 60 μg/kg) was injected just before tPA. Neutrophil response in peripheral blood and in the infarct area was quantified in parallel to the infarct volume. Protease matrix metallopeptidase 9 (MMP-9) release from circulating neutrophils was analyzed by immunochemistry and zymography. Vascular reactivity and hemorrhagic volume in the infarct area was also assessed.

Results

Twenty four hours after ischemia and tPA, G-CSF administration induced a significant increase of neutrophils in peripheral blood (P <0.05). At 72 hours post-ischemia, G-CSF was significantly associated with an increased risk of hemorrhage in the infarct area (2.5 times more likely; P <0.05) and significant cerebral endothelium-dependent dysfunction. Ex vivo, an increased MMP-9 release from neutrophils after tPA administration correlated to the increased hemorrhagic risk (P <0.05). In parallel, G-CSF administration was associated with a decreased neutrophil infiltration in the infarct area (-50%; P <0.05), with a concomitant significant neuroprotective effect (infarct volume: -40%; P <0.05).

Conclusions

We demonstrate that G-CSF potentiates the risk of hemorrhage in experimental stroke when used in combination with tPA by inducing neutrophilia. This effect is concomitant to an increased MMP-9 release from peripheral neutrophils induced by the tPA treatment. These results highlight the potential hemorrhagic risk of associating G-CSF to thrombolysis during the acute phase of stroke.

Fluid-attenuated inversion recovery hyperintensity correlates with matrix metalloproteinase-9 level and hemorrhagic transformation in acute ischemic stroke

BACKGROUND AND PURPOSE

Matrix metalloproteinase-9 (MMP-9) is elevated in patients with acute stroke who later develop hemorrhagic transformation (HT). It is controversial whether early fluid-attenuated inversion recovery (FLAIR) hyperintensity on brain MRI predicts hemorrhagic transformation (HT). We assessed whether FLAIR hyperintensity was associated with MMP-9 and HT.

METHODS

We analyzed a prospectively collected cohort of acute stroke subjects with acute brain MRI images and MMP-9 values within the first 12 hours after stroke onset. FLAIR hyperintensity was measured using a signal intensity ratio between the stroke lesion and corresponding normal contralateral hemisphere. MMP-9 was measured using enzyme-linked immunosorbent assay. The relationships between FLAIR ratio (FR), MMP-9, and HT were evaluated.

RESULTS

A total of 180 subjects were available for analysis. Patients were imaged with brain MRI at 5.6±4.3 hours from last seen well time. MMP-9 blood samples were drawn within 7.7±4.0 hours from last seen well time. The time to MRI (r=0.17, P=0.027) and MMP-9 level (r=0.29, P<0.001) were each associated with FR. The association between MMP-9 and FR remained significant after multivariable adjustment (P<0.001). FR was also associated with HT and symptomatic hemorrhage (P=0.012).

CONCLUSIONS

FR correlates with both MMP-9 level and risk of hemorrhage. FLAIR changes in the acute phase of stroke may predict hemorrhagic transformation, possibly as a reflection of altered blood-brain barrier integrity.

Intravenous tissue-type plasminogen activator therapy is an independent risk factor for symptomatic intracerebral hemorrhage after carotid endarterectomy

BACKGROUND

Carotid endarterectomy (CEA) for symptomatic carotid artery stenosis and intravenous tissue-type plasminogen activator (IV-tPA) for acute ischemic stroke are proven therapies; however, the safety of CEA in stroke patients who recently received IV-tPA has not been established.

OBJECTIVE

To evaluate the safety of CEA in stroke patients who recently received IV-tPA.

METHODS

A retrospective review of patients who underwent CEA for symptomatic carotid artery stenosis was performed. The primary end point was postoperative symptomatic intracerebral hemorrhage (sICH). A univariate analysis of potential risk factors for sICH, including IV-tPA therapy, timing of CEA, degree of stenosis, and stroke severity, was performed. Factors with a value of P < .1 on univariate analysis were tested further.

RESULTS

Among 142 patients, 3 suffered sICH after CEA: 2 of 11 patients treated with IV-tPA (18.2%) and 1 of 131 patients not treated with IV-tPA (0.8%). Both IV-tPA patients suffering sICH underwent CEA within 3 days of tPA administration. On univariate analysis, IV-tPA (P = .02), female sex (P = .09), shorter time between ischemic event and CEA (P = .06), and lower mean arterial pressure during the first 48 hours of admission (P = .08) were identified as risk factors for sICH. On multivariate analysis, IV-tPA was the only significant risk factor (P = .002 by stepwise logistic regression; P = .03 by nominal logistic regression).

CONCLUSION

This study indicates that IV-tPA is an independent risk factor for sICH after CEA. This suggests that CEA should be pursued cautiously in patients who recently received IV-tPA. Early surgery may be associated with an increased risk for sICH.

ABBREVIATIONS

CEA, carotid endarterectomyIV-tPA, intravenous recombinant tissue-type plasminogen activatorMAP, mean arterial pressureNASCET, North American Symptomatic Carotid Endarterectomy TrialNIHSS, National Institutes of Health Stroke ScaleNINDS, National Institute of Neurological Disorders and StrokesICH, symptomatic intracerebral hemorrhageTIA, transient ischemic attack.

Mmp-9 inhibition: a therapeutic strategy in ischemic stroke

Ischemic stroke is a leading cause of disability worldwide. In cerebral ischemia there is an enhanced expression of matrix metallo-proteinase-9 (MMP-9), which has been associated with various complications including excitotoxicity, neuronal damage, apoptosis, blood-brain barrier (BBB) opening leading to cerebral edema, and hemorrhagic transformation. Moreover, the tissue plasminogen activator (tPA), which is the only US-FDA approved treatment of ischemic stroke, has a brief 3 to 4 h time window and it has been proposed that detrimental effects of tPA beyond the 3 h since the onset of stroke are derived from its ability to activate MMP-9 that in turn contributes to the breakdown of BBB. Therefore, the available literature suggests that MMP-9 inhibition can be of therapeutic importance in ischemic stroke. Hence, combination therapies of MMP-9 inhibitor along with tPA can be beneficial in ischemic stroke. In this review we will discuss the current status of various strategies which have shown neuroprotection and extension of thrombolytic window by directly or indirectly inhibiting MMP-9 activity. In the introductory part of the review, we briefly provide an overview on ischemic stroke, commonly used models of ischemic stroke and a role of MMP-9 in ischemia. In next part, the literature is organized as various approaches which have proven neuroprotective effects through direct or indirect decrease in MMP-9 activity, namely, using biotherapeutics, involving MMP-9 gene inhibition using viral vectors; using endogenous inhibitor of MMP-9, repurposing of old drugs such as minocycline, new chemical entities like DP-b99, and finally other approaches like therapeutic hypothermia.

Recommendations for the management of cerebral and cerebellar infarction with swelling: a statement for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

There are uncertainties surrounding the optimal management of patients with brain swelling after an ischemic stroke. Guidelines are needed on how to manage this major complication, how to provide the best comprehensive neurological and medical care, and how to best inform families facing complex decisions on surgical intervention in deteriorating patients. This scientific statement addresses the early approach to the patient with a swollen ischemic stroke in a cerebral or cerebellar hemisphere.

METHODS

The writing group used systematic literature reviews, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge. The panel reviewed the most relevant articles on adults through computerized searches of the medical literature using MEDLINE, EMBASE, and Web of Science through March 2013. The evidence is organized within the context of the American Heart Association framework and is classified according to the joint American Heart Association/American College of Cardiology Foundation and supplementary American Heart Association Stroke Council methods of classifying the level of certainty and the class and level of evidence. The document underwent extensive American Heart Association internal peer review.

RESULTS

Clinical criteria are available for hemispheric (involving the entire middle cerebral artery territory or more) and cerebellar (involving the posterior inferior cerebellar artery or superior cerebellar artery) swelling caused by ischemic infarction. Clinical signs that signify deterioration in swollen supratentorial hemispheric ischemic stroke include new or further impairment of consciousness, cerebral ptosis, and changes in pupillary size. In swollen cerebellar infarction, a decrease in level of consciousness occurs as a result of brainstem compression and therefore may include early loss of corneal reflexes and the development of miosis. Standardized definitions should be established to facilitate multicenter and population-based studies of incidence, prevalence, risk factors, and outcomes. Identification of patients at high risk for brain swelling should include clinical and neuroimaging data. If a full resuscitative status is warranted in a patient with a large territorial stroke, admission to a unit with neurological monitoring capabilities is needed. These patients are best admitted to intensive care or stroke units attended by skilled and experienced physicians such as neurointensivists or vascular neurologists. Complex medical care includes airway management and mechanical ventilation, blood pressure control, fluid management, and glucose and temperature control. In swollen supratentorial hemispheric ischemic stroke, routine intracranial pressure monitoring or cerebrospinal fluid diversion is not indicated, but decompressive craniectomy with dural expansion should be considered in patients who continue to deteriorate neurologically. There is uncertainty about the efficacy of decompressive craniectomy in patients ≥60 years of age. In swollen cerebellar stroke, suboccipital craniectomy with dural expansion should be performed in patients who deteriorate neurologically. Ventriculostomy to relieve obstructive hydrocephalus after a cerebellar infarct should be accompanied by decompressive suboccipital craniectomy to avoid deterioration from upward cerebellar displacement. In swollen hemispheric supratentorial infarcts, outcome can be satisfactory, but one should anticipate that one third of patients will be severely disabled and fully dependent on care even after decompressive craniectomy. Surgery after a cerebellar infarct leads to acceptable functional outcome in most patients.

CONCLUSIONS

Swollen cerebral and cerebellar infarcts are critical conditions that warrant immediate, specialized neurointensive care and often neurosurgical intervention. Decompressive craniectomy is a necessary option in many patients. Selected patients may benefit greatly from such an approach, and although disabled, they may be functionally independent.

Fluorescent molecular peroxidation products: a prognostic biomarker of early neurologic deterioration after thrombolysis

BACKGROUND AND PURPOSE

Fluorescent molecular peroxidation products (FMPPs) are considered potential markers of molecular oxidative damage and may provoke increased permeability and disruption of the blood-brain barrier. This study aimed to determine the value of FMPPs as a biomarker to predict neurological worsening related to early hemorrhagic transformation.

METHODS

Baseline FMPP levels were measured in 186 consecutive acute ischemic stroke patients before tissue plasminogen activator treatment was administered. A serial FMPP profile (baseline before tissue plasminogen activator treatment, and 1, 2, 12, and 24 hours from treatment) was determined in a subset of 100 patients. Computed tomographic scans were performed at admission and repeated at 24 to 48 hours or after neurological worsening occurred. Symptomatic intracranial hemorrhage was defined as blood at any site in the brain associated with neurological deterioration.

RESULTS

Patients who worsened had higher median FMPP levels compared with those who did not (59.68 [48.63-85.73] versus 44.87 [36.37-58.90] Uf/mL; P=0.035) at baseline. After logistic regression multivariate analysis, FMPP >48.2 Uf/mL together with age, hypertension, and systolic blood pressure remained baseline predictors of worsening at 48 hours. Moreover, baseline FMPP determination helped to distinguish between patients who worsened and those who did not (Integrated Discrimination Improvement index, 5.7%; P=0.0004). Finally, within patients who had worsened at 48 hours, those with symptomatic intracranial hemorrhage had higher FMPP levels (P=0.038).

CONCLUSIONS

FMPPs might be a valuable biomarker of poor early neurological outcome and be related to the appearance of symptomatic intracranial hemorrhage in tissue plasminogen activator-treated patients, one of the most feared neurological complications after thrombolytic treatment of acute ischemic stroke.

Reduction of steroid-induced intraocular pressure elevation in sheep by tissue plasminogen activator

PURPOSE

To investigate whether tissue plasminogen activator (tPA) can prevent and/or reverse steroid-induced IOP elevation in an ovine model.

METHODS

Three animal groups were subjected to bilateral steroid-induced IOP elevation using thrice daily topical ocular prednisolone administration. In the first group (N = 8), one eye each of two sheep was injected intravitreally with 100 μg, 200 μg, 500 μg, or 1 mg human recombinant tPA, while contralateral eyes received vehicle. In the second group (N = 2), one eye was injected intravitreally with tPA (100 μg), while contralateral eyes received vehicle containing L-arginine. In the third group (N = 4), each animal received intravitreal tPA in one eye concurrently with initiation of bilateral steroid administration. IOP was monitored for the duration of the experiment. Tissues from eyes of the third group were used to determine relative gene expression.

RESULTS

In the first and second groups, IOP decreased by 9.7 (±2.8) and 9.7 (±1.6) mm Hg, respectively, 24 hours after tPA administration. In the third group, tPA-treated eyes did not develop IOP elevation with ΔIOP of 11.8 (±1.3) mm Hg 8 days later. In all tPA-treated eyes, IOP remained low until the end of the study. mRNA levels in the trabecular meshwork were decreased for plasminogen activator tissue (PLAT), increased for matrix-metalloproteinase 1 (MMP-1), and stable for plasminogen activator inhibitor 1 (PAI-1), MMP-2, MMP-9, and MMP-13 in tPA-treated eyes compared with contralateral controls. PAI-1 mRNA levels in ciliary processes also remained similar.

CONCLUSIONS

Recombinant human tPA is effective in both preventing and reversing steroid-induced IOP elevation in sheep. Tissue plasminogen activator may be useful as a therapeutic agent in steroid-induced glaucoma.

Pathogenesis of acute stroke and the role of inflammasomes

Inflammation is an innate immune response to infection or tissue damage that is designed to limit harm to the host, but contributes significantly to ischemic brain injury following stroke. The inflammatory response is initiated by the detection of acute damage via extracellular and intracellular pattern recognition receptors, which respond to conserved microbial structures, termed pathogen-associated molecular patterns or host-derived danger signals termed damage-associated molecular patterns. Multi-protein complexes known as inflammasomes (e.g. containing NLRP1, NLRP2, NLRP3, NLRP6, NLRP7, NLRP12, NLRC4, AIM2 and/or Pyrin), then process these signals to trigger an effector response. Briefly, signaling through NLRP1 and NLRP3 inflammasomes produces cleaved caspase-1, which cleaves both pro-IL-1β and pro-IL-18 into their biologically active mature pro-inflammatory cytokines that are released into the extracellular environment. This review will describe the molecular structure, cellular signaling pathways and current evidence for inflammasome activation following cerebral ischemia, and the potential for future treatments for stroke that may involve targeting inflammasome formation or its products in the ischemic brain.

Tissue plasminogen activator in trabecular meshwork attenuates steroid induced outflow resistance in mice

Tissue plasminogen activator, a serine protease encoded by the PLAT gene is present in the trabecular meshwork (TM) and other ocular tissues and has been reported to be downregulated by treatment with steroids in vitro. Steroids are known to cause changes in outflow facility of aqueous humor in many species. In the present study, we tested whether overexpression of PLAT can prevent and/or reverse the outflow facility of mouse eyes treated with steroids. Animals received bilateral injection with 20 µl of triamcinolone acetonide (TA) (40 mg/ml) suspension subconjunctivally to induce outflow facility changes. Some animals received unilateral intracameral injection with 2 µl of adenoviral suspension [3-4 x 10(12) virus genomes per milliliter (vg/ml)] carrying sheep PLAT cDNA (AdPLAT) either concurrently with TA injection or one week after TA injection, whereas others received bilateral intracameral injection with 2 µl of adenoviral suspension (9 x 10(12) vg/ml) carrying no transgene (AdNull) concurrently with TA injection. Animals were sacrificed one week after AdPLAT or AdNull treatment. Endogenous mRNA expression levels of mouse PAI-1 and MMP-2, -9 and -13 were also measured using qRT-PCR. Outflow facility one week after AdPLAT administration was increased by 60% and 63% respectively for animals that had not or had been pretreated with steroids. Overexpression of PLAT significantly upregulated expression of PAI-1, MMP-2, -9 and -13 compared to the levels found in TA only treated eyes. These findings suggest that overexpression of PLAT in TM of mouse eyes can both prevent and reverse the decrease in outflow facility caused by steroid treatment and is associated with upregulation of MMPs.

Hypoxia-ischemia or excitotoxin-induced tissue plasminogen activator- dependent gelatinase activation in mice neonate brain microvessels

Hypoxia-ischemia (HI) and excitotoxicity are validated causes of neonatal brain injuries and tissue plasminogen activator (t-PA) participates in the processes through proteolytic and receptor-mediated pathways. Brain microvascular endothelial cells from neonates in culture, contain and release more t-PA and gelatinases upon glutamate challenge than adult cells. We have studied t-PA to gelatinase (MMP-2 and MMP-9) activity links in HI and excitotoxicity lesion models in 5 day–old pups in wild type and in t-PA or its inhibitor (PAI-1) genes inactivated mice. Gelatinolytic activities were detected in SDS-PAGE zymograms and by in situ fluorescent DQ-gelatin microscopic zymographies. HI was achieved by unilateral carotid ligature followed by a 40 min hypoxia (8%O₂). Excitotoxic lesions were produced by intra parenchymal cortical (i.c.) injections of 10 µg ibotenate (Ibo). Gel zymograms in WT cortex revealed progressive extinction of MMP-2 and MMP-9 activities near day 15 or day 8 respectively. MMP-2 expression was the same in all strains while MMP-9 activity was barely detectable in t-PA^−/− and enhanced in PAI-1^−/− mice. HI or Ibo produced activation of MMP-2 activities 6 hours post-insult, in cortices of WT mice but not in t-PA^−/− mice. In PAI-1^−/− mice, HI or vehicle i.c. injection increased MMP-2 and MMP-9 activities. In situ zymograms using DQ-gelatin revealed vessel associated gelatinolytic activity in lesioned areas in PAI-1^−/− and in WT mice. In WT brain slices incubated ex vivo, glutamate (200 µM) induced DQ-gelatin activation in vessels. The effect was not detected in t-PA^−/−mice, but was restored by concomitant exposure to recombinant t-PA (20 µg/mL). In summary, neonatal brain lesion paradigms and ex vivo excitotoxic glutamate evoked t-PA-dependent gelatinases activation in vessels. Both MMP-2 and MMP-9 activities appeared t-PA-dependent. The data suggest that vascular directed protease inhibition may have neuroprotection potential against neonatal brain injuries.

Reducing haemorrhagic transformation after thrombolysis for stroke: a strategy utilising minocycline

Haemorrhagic transformation (HT) of recently ischaemic brain is a feared complication of thrombolytic therapy that may be caused or compounded by ischaemia-induced activation of matrix metalloproteinases (MMPs). The tetracycline antibiotic minocycline inhibits matrix MMPs and reduces macroscopic HT in rodents with stroke treated with tissue plasminogen activator (tPA). The West Australian Intravenous Minocycline and TPA Stroke Study (WAIMATSS) aims to determine the safety and efficacy of adding minocycline to tPA in acute ischaemic stroke. The WAIMATSS is a multicentre, prospective, and randomised pilot study of intravenous minocycline, 200 mg 12 hourly for 5 doses, compared with standard care, in patients with ischaemic stroke treated with intravenous tPA. The primary endpoint is HT diagnosed by brain CT and MRI. Secondary endpoints include clinical outcome measures. Some illustrative cases from the early recruitment phase of this study will be presented, and future perspectives will be discussed.

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.

Exploring molecular mechanism underlying Chinese medicine syndrome: a study on correlation between Chinese medicine syndrome and biomarkers for ischemic stroke

OBJECTIVE

To investigate whether Chinese medicine (CM) syndrome is associated with particular molecular mechanism, we explored the correlation between CM syndrome and changes of intercellular adhesion molecule-1 (ICAM-1), matrix metalloproteinase 9 (MMP-9) and heat shock protein 70 (HSP70) in patients with ischemic stroke, which were reported to play an important role in the inflammatory and apoptosis cascade.

METHODS

CM syndrome factors of 175 patients with ischemic stroke were assessed using Ischemic Stroke CM Syndrome Factor Diagnostic Scale (ISTSFDS). The patients were grouped according to the main syndrome factor combinations at different time points based on distribution probability of syndrome factor combinations. Blood levels of ICAM-1, MMP-9 and HSP70 were quantified by enzyme-linked immunosorbent assay.

RESULTS

ICAM-1 expression was significantly higher in the internal-wind+phlegm-dampness+blood-stasis, phlegmdampness+ blood-stasis, internal-fire+phlegm-dampness+blood-stasis group than that in the blood-stasis+qideficiency group within 72 h from stroke onset (P <0.05); HSP70 expression was significantly lower in the phlegm-dampness+blood-stasis, internal-fire+phlegm-dampness+blood-stasis, blood-stasis group than that in the phlegm-dampness+blood-stasis+qi-deficiency group on the 7th day from stroke onset (P<0.05).

CONCLUSIONS

Phlegm-dampness and blood-stasis exist through the whole process of ischemic stroke. An increased level of ICAM-1 and a reduced level of HSP70 reflect the pathological state of phlegm-stasis mutual binding. These results suggest that inflammation and apoptosis induced by cerebral vascular injury in the pathological processes of ischemic stroke are more prominent in the excess syndrome state like phlegm-dampness and blood-stasis.

Fluorometric immunocapture assay for the specific measurement of matrix metalloproteinase-9 activity in biological samples: application to brain and plasma from rats with ischemic stroke

BACKGROUND

Matrix metalloproteinases are important factors in the molecular mechanisms leading to neuronal injury in many neurological disorders. Matrix metalloproteinase (MMP)-9 is up-regulated after cerebral ischemia and neuroinflammation and is actively involved in blood-brain barrier disruption. Current methods of measuring MMP-9 activity, such as gelatin-substrate zymography, are unspecific and arduous. Here we developed an immunocapture assay with high efficiency, specificity, and sensitivity for quantifying endogenously active as well as total MMP-9 activity.

RESULTS

A fluorescence resonance energy transfer (FRET) peptide-based immunocapture assay was developed that enables the accurate assessment of total and active forms of MMP-9 in complex biological samples. The FRET assay demonstrated correct and efficient binding of MMP-9 to a mouse monoclonal MMP-9 antibody and high specificity of the immunocapture antibody for MMP-9. Total and active levels of MMP-9 were measured in rat brain homogenates, plasma, human HT-1080 conditioned media, and RBE4 endothelial cell lysates. The FRET immunocapture assay yielded highly similar results for total MMP-9 activity when compared to gelatin-substrate zymography.

CONCLUSIONS

We suggest that the new FRET peptide-based immunocapture assay is a viable replacement of zymography for sensitive and high throughput quantification of MMP-9 activity in biological samples.

Neurovascular matrix metalloproteinases and the blood-brain barrier

Blood-brain barrier (BBB) leakage and brain edema is a critical part of stroke pathophysiology. In this mini-review, we briefly survey the potential role of matrix metalloproteinases (MMPs) in BBB dysfunction. A large body of data in both experimental models as well as clinical patient populations suggests that MMPs may disrupt BBB permeability and interfere with cell-cell signaling in the neurovascular unit. Hence, ongoing efforts are underway to validate MMPs as potential biomarkers in stroke as well as pursue MMP blockers as therapeutic opportunities. Because BBB perturbations may also occur in neurodegeneration, MMPs and associated neurovascular unit mechanisms may also be potential targets in a broader range of CNS disorders.

Application of proteomics to cerebrovascular disease

While neurovascular diseases such as ischemic and hemorrhagic stroke are the leading causes of disability in the world, the repertoire of therapeutic interventions has remained remarkably limited. There is a dire need to develop new diagnostic, prognostic, and therapeutic options. The study of proteomics is particularly enticing for cerebrovascular diseases such as stroke, which most likely involve multiple gene interactions resulting in a wide range of clinical phenotypes. Currently, rapidly progressing neuroproteomic techniques have been employed in clinical and translational research to help identify biologically relevant pathways, to understand cerebrovascular pathophysiology, and to develop novel therapeutics and diagnostics. Future integration of proteomic with genomic, transcriptomic, and metabolomic studies will add new perspectives to better understand the complexities of neurovascular injury. Here, we review cerebrovascular proteomics research in both preclinical (animal, cell culture) and clinical (blood, urine, cerebrospinal fluid, microdialyates, tissue) studies. We will also discuss the rewards, challenges, and future directions for the application of proteomics technology to the study of various disease phenotypes. To capture the dynamic range of cerebrovascular injury and repair with a translational targeted and discovery approach, we emphasize the importance of complementing innovative proteomic technology with existing molecular biology models in preclinical studies, and the need to advance pharmacoproteomics to directly probe clinical physiology and gauge therapeutic efficacy at the bedside.

Association of dimethylarginines and mediators of inflammation after acute ischemic stroke

Background

Elevated levels of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are accompanied by endothelial dysfunction and predict adverse outcome after ischemic stroke. Via induction of oxidative stress, dimethylarginines are possibly linked to the inflammatory cascade after stroke that is known to considerably contribute to secondary progression of brain injury. We sought to investigate the association between dimethylarginines and inflammatory mediators in patients with acute ischemic stroke.

Methods

Plasma levels of ADMA and SDMA were measured in prospectively collected blood samples of 58 patients with acute ischemic stroke. Blood samples were taken at 6 hours, 12 hours, 24 hours, 3 days and 7 days after onset of symptoms. Analyses of ADMA and SDMA were done by high-performance liquid chromatography-tandem mass spectrometry. Monocyte chemotactic protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), interleukin-6 (IL-6), C-reactive protein (CRP) and S100B as markers of inflammation and brain damage were determined by commercially available immunometric assays. Patient data were compared with control data from 32 age-adjusted healthy volunteers. Baseline stroke severity was evaluated by the National Institutes of Health Stroke Scale (NIHSS) (NIHSS 0 to 1: mild stroke; NIHSS 2 to 8: moderate stroke; NIHSS ≥9: severe stroke).

Results

Plasma ADMA and SDMA levels significantly correlated with blood levels of inflammatory mediators up to day 7 after stroke. On multiple stepwise linear regression analysis ADMA correlated with TIMP-1 at 6 hours, 24 hours, 3 days and 7 days, MMP-9 at 12 hours and IL-6 at 7 days (P <0.05) while SDMA correlated with MCP-1 at 6 hours, 24 hours, 3 days and 7 days as well as IL-6 at 3 days and 7 days (P <0.05).

Conclusions

The levels of the vasoactive compound ADMA as well as levels of its structural isomer SDMA are associated with levels of inflammatory mediators after acute ischemic stroke. Further studies need to elucidate the cause and effect relationship of these crucial players.

Does inhibiting Sur1 complement rt-PA in cerebral ischemia?

Hemorrhagic transformation (HT) associated with recombinant tissue plasminogen activator (rt-PA) complicates and limits its use in stroke. Here, we provide a focused review on the involvement of matrix metalloproteinase 9 (MMP-9) in rt-PA-associated HT in cerebral ischemia, and we review emerging evidence that the selective inhibitor of the sulfonylurea receptor 1 (Sur1), glibenclamide (U.S. adopted name, glyburide), may provide protection against rt-PA-associated HT in cerebral ischemia. Glyburide inhibits activation of MMP-9, ameliorates edema formation, swelling, and symptomatic hemorrhagic transformation, and improves preclinical outcomes in several clinically relevant models of stroke, both without and with rt-PA treatment. A retrospective clinical study comparing outcomes in diabetic patients with stroke treated with rt-PA showed that those who were previously on and were maintained on a sulfonylurea fared significantly better than those whose diabetes was managed without sulfonylureas. Inhibition of Sur1 with injectable glyburide holds promise for ameliorating rt-PA-associated HT in stroke.

CDP-choline treatment increases circulating endothelial progenitor cells in acute ischemic stroke

OBJECTIVES

The increase in circulating endothelial progenitor cells (EPCs) is associated with a better outcome in patients with acute ischemic stroke. CDP-choline (citicoline) increases brain plasticity after experimental stroke. Therefore, we study if citicoline treatment could increase the EPC concentration after ischemic stroke.

METHODS

Forty-eight patients with a first-ever non-lacunar ischemic stroke were consecutively included in the study within 12 hours of symptoms onset. Patients received treatment (n = 26) or non-treatment (n = 22) with oral citicoline (2000 mg/day) from acute phase of ischemic stroke and for 6 weeks. EPC colonies were quantified as early outgrowth colony forming unit-endothelial cell (CFU-EC) at admission (before citicoline treatment) and day 7. We defined the EPC increment during the first week as the difference in the numbers of CFU-EC between day 7 and admission.

RESULTS

CFU-ECs were similar at baseline between patients treated and non-treated with citicoline (7.7±6.1 versus 9.1±7.3 CFU-EC, P = 0.819). However, patients treated with citicoline and recombinant tissue-plasminogen activator (rt-PA) showed a higher EPC increment compared to patients treated only with citicoline or non-treated (35.4±15.9 versus 8.4 ± 8.1 versus 0.9 ± 10.2 CFU-EC, P < 0.0001). In a logistic model, citicoline treatment [odds ratio (OR), 17.6; confidence interval (CI) 95%, 2.3-137.5, P = 0.006] and co-treatment with citicoline and rt-PA (OR, 108.5; CI 95%, 2.9-1094.2, P = 0.001) were independently associated with an EPC increment⩾4 CFU-EC.

CONCLUSION

The administration of citicoline and the co-administration of citicoline and rt-PA increase EPC concentration in acute ischemic stroke.

Anticoagulants affect matrix metalloproteinase 9 levels in blood samples of stroke patients and healthy controls

OBJECTIVES

Matrix metalloproteinase-9 (MMP-9) represents a promising marker for acute stroke management. In clinical studies MMP-9 has been quantified by ELISA using differing protocols. We aimed to establish a valid protocol by evaluation of preanalytics.

DESIGN AND METHODS

Blood from stroke patients (n=28) and healthy controls (n=28) was drawn into tubes containing different anticoagulants (EDTA, citrate, lithium-heparin (heparin) and heparin with proteinase inhibitors) and processed after 0, 60 and 240 min. MMP-9 plasma protein and mRNA from mononuclear leukocytes were determined.

RESULTS

In regard to anticoagulants used, samples showed different MMP-9 protein baseline values and kinetics. Stable MMP-9 protein concentrations were only measured from EDTA samples. Particularly in samples with proteinase inhibitors protein and mRNA concentrations increased over time. Kinetics did not differ between patients and controls.

CONCLUSIONS

Preanalytics plays a key role for determination of MMP-9. EDTA seems to be a valid anticoagulant for MMP-9 protein measurement.

Biomarkers in neurocritical care

The gold standard for assessing neurological function is the bedside clinical examination. However, in neurocritical patients, the signs and symptoms related to the severity of illness can often be ambiguous. It can be hard to distinguish between a severe but stable disease state and one that is dynamic and in a critical decline. Clinicians and family members alike may struggle with the uncertainty of functional outcome prediction. Intermediate biomarkers of brain injury can assist with ongoing clinical management of patients, and in some circumstances can guide prognosis. Used in the right setting, biomarkers in neurocritical care can also aid with decisions to intensify treatment or avoid prolonged and unnecessary therapy. The term biomarker is used in various ways, and here we use it to refer to 3 general types: 1) circulating blood macromolecules, 2) brain imaging, and 3) continuous invasive monitors. Despite its promise, biomarkers have several limitations and should be interpreted in the context of the overall clinical assessment.

Inflammatory and neuroendocrine biomarkers of prognosis after ischemic stroke

Stroke is the third leading cause of mortality in the USA and one of the leading causes of severe morbidity. It is important to provide stroke patients and physicians with the most accurate prognostic information to optimize care and allocation of healthcare resources. Reliable prognostic markers available during the initial phase after acute stroke may aid clinical decision-making. Several interesting candidate biomarkers have been studied to address prognostic questions; this article will focus on selected inflammatory and neuroendocrine markers. The utility of a biomarker is defined by its ability to improve clinical decision-making and add timely information beyond that readily available from clinical examination and routine imaging. This aim has not been completely achieved yet for any biomarkers, but promising data are available and further studies are ongoing.

Safety of early carotid artery stenting after systemic thrombolysis: a single center experience

Background. Patients with acute ischemic stroke due to internal carotid artery (ICA) disease are at high risk of early stroke recurrence. A combination of IV thrombolysis and early carotid artery stenting (CAS) may result in more effective secondary stroke prevention. Objective. We tested safety and durability of early CAS following IV thrombolysis in stroke patients with residual stenosis in the symptomatic ICA. Methods. Of consecutive patients treated with IV rtPA, those with residual ICA stenosis ≥70% or <70% with an ulcerated plaque underwent early CAS (>24 hours). The protocol included pre-rtPA MRI and MR angiography, and post-rtPA carotid ultrasound and CT angiography. Stroke severity was assessed by the NIH Stroke Scale (NIHSS). Three- and twelve-month stent patency was assessed by ultrasound. Twelve-month functional outcome was assessed by the modified Rankin Scale (mRS). Results. Of 145 consecutive IV rtPA-treated patients, 6 (4%) underwent early CAS. Median age was 76 (range 67-78) years, median NIHSS at stroke onset was 12 (range 9-16) and 7 (range 7-8) before CAS. Median onset-to-CAS time was 48 (range 30-94) hours. A single self-expandable stent was implanted to cover the entire lesion in all patients. The procedure was uneventful in all patients. After 12 months, all patients had stent patency, and the functional outcome was favourable (mRS ≤ 2) in all but 1 patient experiencing a recurrent stroke for new-onset atrial fibrillation. Conclusion. This small case series of a single centre suggests that early CAS may be considered a safe alternative to CEA after IV rtPA administration in selected patients at high risk of stroke recurrence.

Matrix metalloproteinase-9 in an exploratory trial of intravenous minocycline for acute ischemic stroke

BACKGROUND AND PURPOSE

Plasma matrix metalloproteinase-9 levels predict posttissue plasminogen activator (tPA) hemorrhage.

METHODS

The authors investigated the effect of minocycline on plasma matrix metalloproteinase-9 in acute ischemic stroke in the Minocycline to Improve Neurological Outcome in Stroke (MINOS) trial and a comparison group.

RESULTS

Matrix metalloproteinase-9 level decreased at 72 hours compared with baseline in MINOS (tPA, P=0.0022; non-tPA, P=0.0066) and was lower than in the non-MINOS comparison group at 24 hours (tPA, P<0.0001; non-tPA, P=0.0019).

CONCLUSIONS

Lower plasma matrix metalloproteinase-9 was seen among tPA-treated subjects in the MINOS trial. Combining minocycline with tPA may prevent the adverse consequences of thrombolytic therapy through suppression of matrix metalloproteinase-9 activity.

Association between neuroserpin and molecular markers of brain damage in patients with acute ischemic stroke

BACKGROUND

Neuroserpin has shown neuroprotective effects in animal models of cerebral ischemia and has been associated with functional outcome after ischemic stroke. Our aim was to study whether neuroserpin serum levels could be associated to biomarkers of excitotoxicity, inflammation and blood brain barrier disruption.

METHODS

We prospectively included 129 patients with ischemic stroke (58.1% male; mean age, 72.4 ± 9.6 years) not treated with tPA within 12 hours (h) of symptoms onset (mean time, 4.7 ± 2.1 h). Poor functional outcome at 3 months was considered as a modified Rankin scale score >2. Serum levels of neuroserpin, Interleukin 6 (IL-6), Intercellular adhesion molecule-1 (ICAM-1), active Matrix metalloproteinase 9 (MMP-9), and cellular fibronectin (cFn) (determined by ELISA) and glutamate (determined by HPLC) were measured on admission, 24 and 72 h. The main variable was considered the decrease of neuroserpin levels within the first 24 h. ROC analysis was used to select the best predictive value for neuroserpin to predict poor functional outcome due to a lack of linearity.

RESULTS

The decrease of neuroserpin levels within the first 24 h was negatively correlated with serum levels at 24 hours of glutamate (r = -0.642), IL-6 (r = -0.678), ICAM-1 (r = -0.345), MMP-9 (r = -0.554) and cFn (r = -0.703) (all P < 0.0001). In the multivariate analysis, serum levels of glutamate (OR, 1.04; CI95%, 1.01-1.06, p = 0.001); IL-6 (OR, 1.4; CI95%, 1.1-1.7, p = 0.001); and cFn (OR, 1.3; CI95%, 1.1-1.6, p = 0.002) were independently associated with a decrease of neuroserpin levels <70 ng/mL at 24 h after adjusting for confounding factors.

CONCLUSIONS

These findings suggest that neuroprotective properties of neuroserpin may be related to the inhibition of excitotoxicity, inflammation, as well as blood brain barrier disruption that occur after acute ischemic stroke.

Translational Stroke Research of the Combination of Thrombolysis and Antioxidant Therapy

Stroke is an enormous public health problem with an imperative need for more effective therapy. Recombinant tissue plasminogen activator is the only licensed drug for acute stroke, but its efficacy may be limited by the toxicity of the compound and by reperfusion injury. The coadministration of neuroprotective drugs could augment the value of thrombolytic therapy, but the evidence in support of this approach is scarce. The use of the free radical trapping NXY-059, either with or without recombinant tissue plasminogen activator, was not successful in Phase III studies. However, these results could reflect its weak antioxidant capacity, poor blood–brain barrier penetration, and lack of synergism with recombinant tissue plasminogen activator as well as the overly broad treatment window used in the reported trials. This article contends that further translational research should explore newer antioxidant drugs in combination with thrombolytic agents, but only if the combination yields additive or synergistic effects in preclinical thromboembolic models or in biomarker-assisted Phase II studies. Edaravone and novel nitrones endowed with a better pharmacokinetic profile or multitarget and thrombolytic activity are discussed as well as the latest research data on uric acid, a strong endogenous antioxidant in blood that is early consumed after acute stroke. The coadministration of uric acid and recombinant tissue plasminogen activator has shown to provide synergistic neuroprotection in experimental thromboembolic models and to lessen several biomarkers of oxidative stress in patients with acute stroke. The clinical efficacy of uric acid is currently under investigation in a Phase III trial that follows current recommendations of also evaluating surrogate biomarkers of treatment effects.