Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0038454 (stroke)
147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The haemorrhagic transformation in ischemic stroke involves disruption of the integrity of the microvascular beds, partially based on the action of matrix metalloproteinases (MMPs). The objective of the present study was to evaluate the contribution of microvascular endothelial cells from human brain (HBECs) to MMPs' expression and regulation under conditions relevant to brain ischemia. MMPs and their inhibitors were examined with zymography, Western-blotting, ELISA and MMP-activity assay in cultured HBECs. Four-hour hypoxia (pO(2)=60 mmHg) elevated the level of MMP-9 in the supernatant of the HBECs and this early response required collagen-matrix. Active oxygen species sustained the increased MMP-9 activity for at least 24 h. In the post-hypoxic period 20 micro mol/L H(2)O(2) caused a 6-fold increase in the specific activity of MMP-9 over the normoxic cells and a comparable effect was exerted by thrombin (50 nmol/L) and leukocyte elastase (10 nmol/L). The role of NF-kappaB, a redox-state sensitive transcription factor, was evaluated with immunofluorescence confocal microscopy and immunoblotting of nuclear and cytoplasmic extracts. The oxidative stress-dependent MMP-9 induction was accompanied by a significant increase in the NF-kappaB localized in the nuclei and these responses were blunted with a proteasome inhibitor (MG132). Consequently, according to our in vitro data HBECs are a source of MMP-9, which is under the control of triggers relevant to the ischemic/reperfused brain (reactive oxygen species, thrombus and inflammation related proteases) and this regulation is partially based on NF-kappaB activation. The reported regulation of endothelium-derived MMP-9 supports its potential involvement in the post-hypoxic disturbances of the cerebral microcirculation.
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PMID:Matrix metalloproteinase-9 expression in post-hypoxic human brain capillary endothelial cells: H2O2 as a trigger and NF-kappaB as a signal transducer. 1295 23

Although thrombolysis with tissue plasminogen activator (tPA) is a stroke therapy approved by the US Food and Drug Administration, its efficacy may be limited by neurotoxic side effects. Recently, proteolytic damage involving matrix metalloproteinases (MMPs) have been implicated. In experimental embolic stroke models, MMP inhibitors decreased cerebral hemorrhage and injury after treatment with tPA. MMPs comprise a family of zinc endopeptidases that can modify several components of the extracellular matrix. In particular, the gelatinases MMP-2 and MMP-9 can degrade neurovascular matrix integrity. MMP-9 promotes neuronal death by disrupting cell-matrix interactions, and MMP-9 knockout mice have reduced blood-brain barrier leakage and infarction after cerebral ischemia. Hence it is possible that tPA upregulates MMPs in the brain, and that subsequent matrix degradation causes brain injury. Here we show that tPA upregulates MMP-9 in cell culture and in vivo. MMP-9 levels were lower in tPA knockouts compared with wild-type mice after focal cerebral ischemia. In human cerebral microvascular endothelial cells, MMP-9 was upregulated when recombinant tPA was added. RNA interference (RNAi) suggested that this response was mediated by the low-density lipoprotein receptor-related protein (LRP), which avidly binds tPA and possesses signaling properties. Targeting the tPA-LRP signaling pathway in brain may offer new approaches for decreasing neurotoxicity and improving stroke therapy.
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PMID:Lipoprotein receptor-mediated induction of matrix metalloproteinase by tissue plasminogen activator. 1296 Sep 61

The inflammatory response that exacerbates cerebral injury after ischemia is an attractive therapeutic target: it progresses over days and strongly contributes to worsening of the neurologic outcome. The authors show that, after transient ischemic injury to the rat brain, systemic application of interferon-beta (IFN-beta), a cytokine with antiinflammatory properties, attenuated the development of brain infarction. Serial magnetic resonance imaging (MRI) showed that IFN-beta treatment reduced lesion volume on diffusion-weighted MRI by 70% (P < 0.01) at 1 day after stroke. IFN-beta attenuated the leakage of contrast agent through the blood-brain barrier (P < 0.005), indicating a better-preserved blood-brain barrier integrity. Both control and IFN-beta-treated animals showed a similar degree of relative hyperperfusion of the lesioned hemisphere, indicating that neuroprotection by IFN-beta was not mediated by improved cerebral perfusion as assessed 24 hours after stroke onset. IFN-beta treatment resulted in an 85% reduction (P < 0.0001) in infarct volume 3 weeks later, as determined from T2-weighted MRI and confirmed by histology. This effect was achieved even when treatment was started 6 hours after stroke onset. Quantitative immunohistochemistry at 24 hours after stroke onset showed that IFN-beta almost completely prevented the infiltration of neutrophils and monocytes into the brain. Gelatinase zymography showed that this effect was associated with a decrease in matrix metalloproteinase-9 expression. In conclusion, treatment with the antiinflammatory cytokine IFN-beta affords significant neuroprotection against ischemia/reperfusion injury, and within a relatively long treatment window. Because IFN-beta has been approved for clinical use, it may be rapidly tested in a clinical trial for its efficacy against human stroke.
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PMID:Interferon-beta blocks infiltration of inflammatory cells and reduces infarct volume after ischemic stroke in the rat. 1297 19

Cerebral hemorrhage associated with antithrombotic and thrombolytic therapy in acute stroke continues to present a major clinical problem. Rupture of the cerebral microvasculature involves the degradation and remodeling of extracellular matrix. Here we demonstrated that the delayed administration of heparin 3 hours after photothrombotic middle cerebral artery occlusion (MCAO) caused cerebral hemorrhage in wild-type (WT) mice but not in tissue plasminogen activator (tPA)-deficient knockout (KO) mice. Heparin administration increased tPA activity and its mRNA expression at 6 and 12 hours after MCAO in the ischemic hemispheres of WT mice. The expression of tPA was enhanced in microglial cells in the ischemic border zone. We also observed an exacerbation of matrix metalloproteinase (MMP) 9 expression at the mRNA level and its conversion to an active form after heparin administration in the ischemic hemisphere in WT mice but not in tPA KO mice. The increased MMP 9 expression was localized in microglial cells and endothelial cells. These findings suggest that endogenous tPA, through the enhancement of MMP 9 expression and proteolytic activation, plays an essential role in the pathogenesis of heparin-produced cerebral hemorrhage. Targeting tPA, MMP 9, or both may provide a new approach for preventing cerebral hemorrhage associated with antithrombotic therapy for stroke in humans.
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PMID:Essential role of endogenous tissue plasminogen activator through matrix metalloproteinase 9 induction and expression on heparin-produced cerebral hemorrhage after cerebral ischemia in mice. 1463 Aug 14

Sixteen patients with acute middle cerebral artery stroke were studied to correlate neuroinflammatory markers with perfusion- and diffusion-weighted magnetic resonance imaging (MRI) lesion volumes (PWI and DWI). At arrival (less than 6 hours), plasmatic matrix metalloproteinase (MMP)-9, MMP-2, interleukin (IL)-6, IL-8, intercellular adhesion molecule (ICAM)-1, and tumor necrosis factor (TNF)-alpha were serially measured (by ELISA), and MRI was performed. In cerebral ischemia, tissue destruction seems related to matrix metalloproteinases expression because baseline MMP-9 was the only predictor of the infarct volume measured as a DWI lesion (lineal regression: b = 0.50, 0.25-0.74; P < 0.001). Moreover, the extent of hypoperfused brain area (PWI) was associated with a proinflammatory cytokine release in the next hours (TNF-alpha and IL-6).
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PMID:Plasmatic level of neuroinflammatory markers predict the extent of diffusion-weighted image lesions in hyperacute stroke. 1466 35

An important step in the cascade leading to neuronal cell death is degradation of laminin and other components of the brain extracellular matrix by microglia-derived proteases. Excitotoxic cell death of murine hippocampal neurones in vivo can be prevented by inhibitors of tissue plasminogen activator (tPA) or by inhibitors of plasmin. Plasmin is a potent activator of the matrix metalloproteinases (MMPs), which are made by resident and recruited leukocytes following CNS injury. In this study, we show, using Taqman RT-PCR, that MMP mRNAs, but not other calcium-dependent proteases such as calpain mRNAs, are acutely up-regulated after an excitotoxic challenge in vivo. alpha(2)-antiplasmin or BB-3103, a broad-spectrum inhibitor of the MMPs, co-injected with kainic acid into the striatum, inhibits excitotoxic cell death in the rat striatum, and reduces both the number of recruited macrophages and the size of the lesion. We also show that leukocyte populations differentially express MMPs, which may account, in part, for the expression profile we observe in the challenged brain. Our results show that inhibition of the MMPs in the rat will prevent kainic acid-induced cell death in the brain. These studies suggest that MMP inhibitors have therapeutic potential for use in stroke, and support the increasing evidence that microglial activation may contribute to neuronal cell death.
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PMID:Reduction of excitotoxicity and associated leukocyte recruitment by a broad-spectrum matrix metalloproteinase inhibitor. 1518 40

Activation of the 5-lipoxygenase (5-LO) pathway leads to the biosynthesis of proinflammatory leukotriene lipid mediators. Genetic studies have associated 5-LO and its accessory protein, 5-LO-activating protein, with cardiovascular disease, myocardial infarction and stroke. Here we show that 5-LO-positive macrophages localize to the adventitia of diseased mouse and human arteries in areas of neoangiogenesis and that these cells constitute a main component of aortic aneurysms induced by an atherogenic diet containing cholate in mice deficient in apolipoprotein E. 5-LO deficiency markedly attenuates the formation of these aneurysms and is associated with reduced matrix metalloproteinase-2 activity and diminished plasma macrophage inflammatory protein-1alpha (MIP-1alpha; also called CCL3), but only minimally affects the formation of lipid-rich lesions. The leukotriene LTD(4) strongly stimulates expression of MIP-1alpha in macrophages and MIP-2 (also called CXCL2) in endothelial cells. These data link the 5-LO pathway to hyperlipidemia-dependent inflammation of the arterial wall and to pathogenesis of aortic aneurysms through a potential chemokine intermediary route.
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PMID:The 5-lipoxygenase pathway promotes pathogenesis of hyperlipidemia-dependent aortic aneurysm. 1534 Apr 8

Reperfusion therapy with tissue plasminogen activator (tPA) is a rational therapy for acute ischemic stroke. Properly titrated use of tPA improves clinical outcomes. However, there is also an associated risk of hemorrhagic transformation after tPA therapy. Emerging data now suggest that some of these potentially neurotoxic side effects of tPA may be due to its signaling actions in the neurovascular unit. Besides its intended role in clot lysis, tPA is also an extracellular protease and signaling molecule in brain. tPA mediates matrix remodeling during brain development and plasticity. By interacting with the NMDA-type glutamate receptor, tPA may amplify potentially excitotoxic calcium currents. At selected concentrations, tPA may be vasoactive. Finally, by augmenting matrix metalloproteinase (MMP) dysregulation after stroke, tPA may degrade extracellular matrix integrity and increase risks of neurovascular cell death, blood-brain barrier leakage, edema, and hemorrhage. Understanding these pleiotropic actions of tPA may reveal new therapeutic opportunities for combination stroke therapy.
Stroke 2004 Nov
PMID:Mechanisms of hemorrhagic transformation after tissue plasminogen activator reperfusion therapy for ischemic stroke. 1545 42

The aim in this study was to investigate whether our experimental model for stroke therapy, flushing the ischemic territory with saline prior to reperfusion, could ameliorate disruption of microvascular integrity by reducing matrix metalloproteinase (MMP) expression during reperfusion. Stroke in Sprague Dawley rats (n = 42) was induced by a 2-h right middle cerebral artery (MCA) occlusion using a novel intraluminal hollow filament. Prior to reperfusion, 24 of the ischemic rats received 6ml isotonic saline at 37 degrees C infused into the ischemic area through the filament. Brain edema was determined by comparing the percentage difference in brain volume between the right and left (contralateral to stroke site) hemispheres, while the expressions of MMP-2 and -9 mRNA were analyzed by real-time reverse transcriptase-polymerase chain reaction (real-time RT-PCR). A significant (p < 0.01) brain edema, determined by an increased brain volume of 19 +/- 4%, and overexpression of the mRNA encoding MMPs, determined by increased relative mRNA level ratio, were found in ischemic rats. The brain damage, in terms of brain edema (4 +/- 1%) and overexpression of MMPs, was significantly (p < 0.05) ameliorated as a result of saline flushing into the ischemic territory prior to reperfusion. This study has enhanced our understanding of the causal mechanisms by which the neuroprotective effect of ischemic area "flushing" can be achieved.
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PMID:Reduced brain edema and matrix metalloproteinase (MMP) expression by pre-reperfusion infusion into ischemic territory in rat. 1553 Oct 84

The spontaneously hypertensive stroke-prone rat (SHR-SP) is an experimental model of malignant hypertension which lead to secondary alterations of the extracellular matrix. Our aim was to determine ACE-inhibitor related changes of proteases involved in the reconstruction of the extracellular matrix in the brain. Twelve SHR-SP rats were randomized into two groups. Each group was treated with either an antihypertensive dose of ramipril or placebo for 6 months. Brain tissue plasminogen activator (t-PA) and urokinase (u-PA) were quantified by using casein-dependent plasminogen zymography, matrix metalloproteinase (MMP)-2 and MMP-9, by MMP-zymography, and tissue inhibitor of MMP (TIMP)-1 and -2, by reverse zymography. The amounts of u-PA, t-PA, and MMPs were significantly reduced in animals treated with ACE inhibitor. Plasminogen zymography showed a 39% reduction of u-PA in the basal ganglia (p < 0.0001); t-PA expression was reduced by 26% in the cortex and by 33% in the basal ganglia (p < 0.0001). MMP-2 expression was reduced by 15% in the cortex (p < 0.05) and by 10% in the basal ganglia (p < 0.05); MMP-9 expression significantly decreased by 37% in the cortex and by 25% in the basal ganglia (p < 0.0001 each). No differences were observed in the amount of TIMP-1 or TIMP-2. These findings provide new insights into the biochemical mechanisms underlying extracellular matrix proliferation and its modulation by ACE inhibitors. Therapeutic alterations that influence the proteolytic systems might prove important in the prevention of extracellular matrix accumulation and secondary microvascular vessel wall changes.
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PMID:ACE inhibition reduces activity of the plasminogen/plasmin and MMP systems in the brain of spontaneous hypertensive stroke-prone rats. 1572 Dec 22


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