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Hyperglycemia promotes tissue plasminogen activator-induced hemorrhage by Increasing superoxide production.

ABSTRACT: Risk of intracerebral hemorrhage is the primary factor limiting use of tissue plasminogen activator (tPA) for stroke. Clinical studies have established an association between admission hyperglycemia and the risk of hemorrhage with tPA use, independent of prior diabetes. Here we used an animal model of tPA-induced reperfusion hemorrhage to determine if this clinical association reflects a true causal relationship.Rats underwent 90 minutes of focal ischemia, and tPA infusion was begun 10 minutes prior to vessel reperfusion. Glucose was administered during ischemia to generate blood levels ranging from 5.9 ± 1.8mM (normoglycemia) to 21 ± 2.3mM. In some studies, apocynin was administered to block superoxide production by nicotinamide adenine dinucleotide phosphate (NADPH). Brains were harvested 1 hour or 3 days after reperfusion to evaluate the effects of hyperglycemia and apocynin on oxidative stress, blood-brain barrier breakdown, infarct volume, and hemorrhage volume.Rats that were hyperglycemic during tPA infusion had diffusely increased blood-brain barrier permeability in the postischemic territory, and a 3- to 5-fold increase in intracerebral hemorrhage volumes. The hyperglycemic rats also showed increased superoxide formation in the brain parenchyma and vasculature during reperfusion. The effects of hyperglycemia on superoxide production, blood-brain barrier disruption, infarct size, and hemorrhage were all attenuated by apocynin.These findings demonstrate a causal relationship between hyperglycemia and hemorrhage in an animal model of tPA stroke treatment, and suggest that this effect of hyperglycemia is mediated through an increase in superoxide production by NADPH oxidase.

SUBMITTER: Won SJ

PROVIDER: S-EPMC4554391 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Hyperglycemia promotes tissue plasminogen activator-induced hemorrhage by Increasing superoxide production.

Won Seok Joon SJ Tang Xian Nan XN Suh Sang Won SW Yenari Midori A MA Swanson Raymond A RA

Annals of neurology 20111014 4

<h4>Objective</h4>Risk of intracerebral hemorrhage is the primary factor limiting use of tissue plasminogen activator (tPA) for stroke. Clinical studies have established an association between admission hyperglycemia and the risk of hemorrhage with tPA use, independent of prior diabetes. Here we used an animal model of tPA-induced reperfusion hemorrhage to determine if this clinical association reflects a true causal relationship.<h4>Methods</h4>Rats underwent 90 minutes of focal ischemia, and t ...[more]

PMID: 22002675

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Project description:Background: Thrombolysis with tissue plasminogen activator (tPA) remains the only approved drug therapy for acute ischemic stroke. However, delayed tPA treatment is associated with an increased risk of brain hemorrhage. In this study, we assessed whether QiShenYiQi (QSYQ), a compound Chinese medicine, can attenuate tPA-induced brain edema and hemorrhage in an experimental stroke model. Methods: Male mice were subjected to ferric chloride-induced carotid artery thrombosis followed by mechanical detachment of thrombi. Then mice were treated with QSYQ at 2.5 h followed by administration of tPA (10 mg/kg) at 4.5 h. Hemorrhage, infarct size, neurological score, cerebral blood flow, Evans blue extravasation, FITC-labeled albumin leakage, tight and adherens junction proteins expression, basement membrane proteins expression, matrix metalloproteinases (MMPs) expression, leukocyte adhesion, and leukocyte infiltration were assessed 24 h after tPA administration. Results: Compared with tPA alone treatments, the combination therapy of QSYQ and tPA significantly reduced hemorrhage, infarction, brain edema, Evans blue extravasation, albumin leakage, leukocyte adhesion, MMP-9 expression, and leukocyte infiltration at 28.5 h after stroke. The combination also significantly improved the survival rate, cerebral blood flow, tight and adherens junction proteins (occludin, claudin-5, junctional adhesion molecule-1, zonula occludens-1, VE-cadherin, α-catenin, β-catenin) expression, and basement membrane proteins (collagen IV, laminin) expression. Addition of QSYQ protected the downregulated ATP 5D and upregulated p-Src and Caveolin-1 after tPA treatment. Conclusion: Our results show that QSYQ inhibits tPA-induced brain edema and hemorrhage by protecting the blood-brain barrier integrity, which was partly attributable to restoration of energy metabolism, protection of inflammation and Src/Caveolin signaling activation. The present study supports QSYQ as an effective adjunctive therapy to increase the safety of delayed tPA thrombolysis for ischemic stroke.

Project description:The neurovascular unit provides a dynamic interface between the circulation and central nervous system. Disruption of neurovascular integrity occurs in numerous brain pathologies including neurotrauma and ischaemic stroke. Tissue plasminogen activator is a serine protease that converts plasminogen to plasmin, a protease that dissolves blood clots. Besides its role in fibrinolysis, tissue plasminogen activator is abundantly expressed in the brain where it mediates extracellular proteolysis. However, proteolytically active tissue plasminogen activator also promotes neurovascular disruption after ischaemic stroke; the molecular mechanisms of this process are still unclear. Tissue plasminogen activator is naturally inhibited by serine protease inhibitors (serpins): plasminogen activator inhibitor-1, neuroserpin or protease nexin-1 that results in the formation of serpin:protease complexes. Proteases and serpin:protease complexes are cleared through high-affinity binding to low-density lipoprotein receptors, but their binding to these receptors can also transmit extracellular signals across the plasma membrane. The matrix metalloproteinases are the second major proteolytic system in the mammalian brain, and like tissue plasminogen activators are pivotal to neurological function but can also degrade structures of the neurovascular unit after injury. Herein, we show that tissue plasminogen activator potentiates neurovascular damage in a dose-dependent manner in a mouse model of neurotrauma. Surprisingly, inhibition of activity following administration of plasminogen activator inhibitor-1 significantly increased cerebrovascular permeability. This led to our finding that formation of complexes between tissue plasminogen activator and plasminogen activator inhibitor-1 in the brain parenchyma facilitates post-traumatic cerebrovascular damage. We demonstrate that following trauma, the complex binds to low-density lipoprotein receptors, triggering the induction of matrix metalloproteinase-3. Accordingly, pharmacological inhibition of matrix metalloproteinase-3 attenuates neurovascular permeability and improves neurological function in injured mice. Our results are clinically relevant, because concentrations of tissue plasminogen activator: plasminogen activator inhibitor-1 complex and matrix metalloproteinase-3 are significantly elevated in cerebrospinal fluid of trauma patients and correlate with neurological outcome. In a separate study, we found that matrix metalloproteinase-3 and albumin, a marker of cerebrovascular damage, were significantly increased in brain tissue of patients with neurotrauma. Perturbation of neurovascular homeostasis causing oedema, inflammation and cell death is an important cause of acute and long-term neurological dysfunction after trauma. A role for the tissue plasminogen activator-matrix metalloproteinase axis in promoting neurovascular disruption after neurotrauma has not been described thus far. Targeting tissue plasminogen activator: plasminogen activator inhibitor-1 complex signalling or downstream matrix metalloproteinase-3 induction may provide viable therapeutic strategies to reduce cerebrovascular permeability after neurotrauma.

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Hyperglycemia promotes tissue plasminogen activator-induced hemorrhage by Increasing superoxide production.

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Hyperglycemia promotes tissue plasminogen activator-induced hemorrhage by Increasing superoxide production.

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