Hemorrhagic Transformation Of Ischemic Stroke Research Articles

Spot Sign in Hemorrhagic Transformation of Ischemic Stroke.

Spot Sign in Hemorrhagic Transformation of Ischemic Stroke.

Alleviating Recombinant Tissue Plasminogen Activator-induced Hemorrhagic Transformation in Ischemic Stroke via Targeted Delivery of a Ferroptosis Inhibitor.

Intravenous thrombolysis with recombinant tissue plasminogen activator (rtPA) is the primary treatment for ischemic stroke. However, rtPA treatment can substantially increase blood-brain barrier (BBB) permeability and susceptibility to hemorrhagic transformation. Herein, the mechanism underlying the side effects of rtPA treatment is investigated and demonstrated that ferroptosis plays an important role. The ferroptosis inhibitor, liproxstatin-1 (Lip) is proposed to alleviate the side effects. A well-designed macrocyclic carrier, glucose-modified azocalix[4]arene (GluAC4A), is prepared to deliver Lip to the ischemic site. GluAC4A bound tightly to Lip and markedly improved its solubility. Glucose, modified at the upper rim of GluAC4A, imparts BBB targeting to the drug delivery system owing to the presence of glucose transporter 1 on the BBB surface. The responsiveness of GluAC4A to hypoxia due to the presence of azo groups enabled the targeted release of Lip at the ischemic site. GluAC4A successfully improved drug accumulation in the brain, and Lip@GluAC4A significantly reduced ferroptosis, BBB leakage, and neurological deficits induced by rtPA in vivo. These findings deepen the understanding of the side effects of rtPA treatment and provide a novel strategy for their effective mitigation, which is of great significance for the treatment and prognosis of patients with ischemic stroke.

YTHDF2-regulated matrilin-3 mitigates post-reperfusion hemorrhagic transformation in ischemic stroke via the PI3K/AKT pathway.

Hemorrhagic transformation can complicate ischemic strokes after recanalization treatment within a time window that requires early intervention. To determine potential therapeutic effects of matrilin-3, rat cerebral ischemia-reperfusion was produced using transient middle cerebral artery occlusion (tMCAO); intracranial hemorrhage and infarct volumes were assayed through hemoglobin determination and 2,3,5-triphenyltetrazoliumchloride (TTC) staining, respectively. Oxygen-glucose deprivation (OGD) modeling of ischemia was performed on C8-D1A cells. Interactions between matrilin-3 and YTH N6-methyladenosine RNA binding protein F2 (YTHDF2) were determined using RNA immunoprecipitation assay and actinomycin D treatment. Reperfusion after tMCAO modeling increased hemorrhage, hemoglobin content, and infarct volumes; these were alleviated by matrilin treatment. Matrilin-3 was expressed at low levels and YTHDF2 was expressed at high levels in ischemic brains. In OGD-induced cells, matrilin-3 was negatively regulated by YTHDF2. Matrilin-3 overexpression downregulated p-PI3K/PI3K, p-AKT/AKT, ZO-1, VE-cadherin and occludin, and upregulated p-JNK/JNK in ischemic rat brains; these effects were reversed by LY294002 (a PI3K inhibitor). YTHDF2 knockdown inactivated the PI3K/AKT pathway, inhibited inflammation and decreased blood-brain barrier-related protein levels in cells; these effects were reversed by matrilin-3 deficiency. These results indicate that YTHDF2-regulated matrilin-3 protected ischemic rats against post-reperfusion hemorrhagic transformation via the PI3K/AKT pathway and that matrilin may have therapeutic potential in ischemic stroke.

The role of neuro-inflammatory in the pathogenesis of brain edema and hemorrhagic transformation in ischemic stroke: mechanisms and therapeutic target

Acute cerebrovascular accident is one of the leading causes of disability and death worldwide. Given the significant increase in life expectancy of the population, stroke will remain a serious medical and social problem in the next few decades. Among the various causes of stroke, ischemic brain damage predominates. Ischemic stroke is based on a decrease in the intensity of blood supply to the brain tissues, as a result of which there is a decrease in the delivery to neurons of the required amount of glucose and oxygen, which are required to ensure the normal function of this organ. At the same time, in many cases, spontaneous or medical restoration of blood flow after a period of ischemia is accompanied by a paradoxical increase in damage, and therefore it is advisable to consider the process of damage to brain tissue during circulatory disorders in the context of ischemic-reperfusion injury (IRI). One of the key mechanisms of brain IRP is the inflammatory response. In the process of secondary immune damage to the brain, both mechanisms of innate immunity, manifested by leukocyte infiltration of the damaged brain area, and antigen-dependent reactions of adaptive immunity are involved. One of the most important manifestations of neuroinflammation in cerebral IRI is an increase in transand paracellular permeability of the blood-brain barrier, which underlies the development of vasogenic cerebral edema and hemorrhagic transformation of the focus. This review considers current ideas about the molecular mechanisms that link aseptic inflammation, edema, and hemorrhagic transformation.

Sertraline Pre-Treatment Attenuates Hemorrhagic Transformation Induced in Rats after Cerebral Ischemia Reperfusion via Down Regulation of Neuronal CD163: Involvement of M1/M2 Polarization Interchange and Inhibiting Autophagy

Cerebral ischemia reperfusion (I/R) is one of the neurovascular diseases which leads to severe brain deterioration. Haemorrhagic transformation (HT) is the main complication of ischemic stroke. It exacerbates by reperfusion, causing a more deleterious effect on the brain and death. The current study explored the protective effect of sertraline (Sert) against cerebral I/R in rats by inhibiting HT, together with the molecular pathways involved in this effect. Forty-eight wister male rats were divided into 4 groups: Sham, Sert + Sham, I/R, and Sert + I/R. The ischemic model was induced by bilateral occlusion of the common carotid artery for 20 min, then reperfusion for 24 h. Sertraline (20 mg/kg, p.o.) was administrated for 14 days before exposure to ischemia. Pre-treatment with Sert led to a significant attenuation of oxidative stress and inflammation. In addition, Sert attenuated phosphorylation of extracellular regulated kinases and nuclear factor kappa—p65 expression, consequently modulating microglial polarisation to M2 phenotype. Moreover, Sert prevented the hemorrhagic transformation of ischemic stroke as indicated by the notable decrease in neuronal expression of CD163, activity of Heme oxygenase-2 and matrix metalloproteinase-2 and 9 levels. In the same context, Sert decreased levels of autophagy and apoptotic markers. Furthermore, histological examination, Toluidine blue, and Prussian blue stain aligned with the results. In conclusion, Sert protected against cerebral I/R damage by attenuating oxidative stress, inflammation, autophagy, and apoptotic process. It is worth mentioning that our study was the first to show that Sert inhibited hemorrhagic transformation.Graphical The protective effect of sertraline against injury induced by cerebral ischemia reperfusion via inhibiting Hemorrhagic transformation.

Escin avoids hemorrhagic transformation in ischemic stroke by protecting BBB through the AMPK/Cav-1/MMP-9 pathway.

Hemorrhagic transformation (HT) seriously affects the clinical application of recombinant tissue plasminogen activator (rt-PA). The main strategy for combating HT is to keep the blood-brain barrier (BBB) stable. Escin is the active ingredient of Aesculus hippocastanum and a natural mixture of triterpene saponins, and may play a part in mitigation of HT. This study sought to investigate the effect of Escin in improving rt-PA-induced HT, explore possible mechanisms, and provide new ideas for the treatment of clinical HT. In in vivo experiments, transient middle cerebral artery occlusion (tMCAO) was undertaken in 6-week-old and 12-month-old mice, and rt-PA was administered to induce HT injury. The inhibitory effect of Escin on HT and its protective effect on neurobehavior, the BBB, and cerebrovascular endothelial cells was determined. In in vitro experiments, bEnd.3 cells were injured by oxygen-glucose deprivation/reperfusion (OGD/R) and rt-PA. The protective effect of Escin was measured by the CCK8 assay, release of lactate dehydrogenase (LDH), and expression of tight junction (TJ) proteins. In mechanistic studies, the effect of Escin on the adenosine monophosphate-activated kinase / caveolin-1 / matrix metalloprotease-9 (AMPK/Cav-1/MMP-9) pathway was investigated by employing AMPK inhibitor and Cav-1 siRNA. In mice suffering from ischemia, rt-PA caused HT as well as damage to the BBB and cerebrovascular endothelial cells. Escin reduced the infarct volume, cerebral hemorrhage, improved neurobehavioral deficits, and maintained BBB integrity in rt-PA-treated tMCAO mice while attenuating bEnd.3 cells damage caused by rt-PA and OGD/R injury. Under physiological and pathological conditions, Escin increased the expression of p-AMPK and Cav-1, leading to decreased expression of MMP-9, which further attenuated damage to cerebrovascular endothelial cells, and these effects were verified with AMPK inhibitor and Cav-1 siRNA. We revealed important details of how Escin protects cerebrovascular endothelial cells from HT, these effects were associated with the AMPK/Cav-1/MMP-9 pathway. This study provides experimental foundation for the development of new drugs to mitigate rt-PA-induced HT and the discovery of new clinical application for Escin.

Factors influencing hemorrhagic transformation in ischemic stroke patients with atrial fibrillation: a hospital based-study

BackgroundPatients with ischemic stroke and atrial fibrillation (AF) are at high risk of developing hemorrhagic transformation (HT). The aim of the current study is to evaluate the incidence of hemorrhagic transformation and associated risk factors in a hospital-based sample with ischemic stroke and AF patients. A prospective study with a total of 234 stroke patients with AF was consecutively recruited. HT incidence was determined by computed tomography (CT) or magnetic resonance imaging (MRI). Risk factors associated with HT was identified by comparing patients with and without HT.ResultsThe incidence of HT in ischemic stroke with AF was 22.6%. Univariate analysis established that old age, hypertension, diabetes mellitus, anticoagulant medications, NIHSS, cerebral microbleeds (CMB), superficial siderosis (SS) and size of infarction were significantly more frequent with HT. Multivariable logistic regression analysis demonstrated that old age [odds ratio (OR): 1.05, confidence interval (CI) 1.01–1.09], size of infarction (OR: 2.57, CI 1.06–6.27) and CMB ≥ 10 (OR: 4.68, CI 1.71–12.84) were significantly associated with the risk of HT.ConclusionsOlder age, larger infarction size, and CMB ≥ 10 were risk factors significantly associated with HT.

Cold Case of Thrombolysis: Cold Recombinant Tissue Plasminogen Activator Confers Enhanced Neuroprotection in Experimental Stroke.

Background Thrombolysis and endovascular thrombectomy are the primary treatment for ischemic stroke. However, due to the limited time window and the occurrence of adverse effects, only a small number of patients can genuinely benefit from recanalization. Intraarterial injection of rtPA (recombinant tissue plasminogen activator) based on arterial thrombectomy could improve the prognosis of patients with acute ischemic stroke, but it could not reduce the incidence of recanalization-related adverse effects. Recently, selective brain hypothermia has been shown to offer neuroprotection against stroke. To enhance the recanalization rate of ischemic stroke and reduce the adverse effects such as tiny thrombosis, brain edema, and hemorrhage, we described for the first time a combined approach of hypothermia and thrombolysis via intraarterial hypothermic rtPA. Methods and Results We initially established the optimal regimen of hypothermic rtPA in adult rats subjected to middle cerebral artery occlusion. Subsequently, we explored the mechanism of action mediating hypothermic rtPA by probing reduction of brain tissue temperature, attenuation of blood-brain barrier damage, and sequestration of inflammation coupled with untargeted metabolomics. Hypothermic rtPA improved neurological scores and reduced infarct volume, while limiting hemorrhagic transformation in middle cerebral artery occlusion rats. These therapeutic outcomes of hypothermic rtPA were accompanied by reduced brain temperature, glucose metabolism, and blood-brain barrier damage. A unique metabolomic profile emerged in hypothermic rtPA-treated middle cerebral artery occlusion rats characterized by downregulated markers for energy metabolism and inflammation. Conclusions The innovative use of hypothermic rtPA enhances their combined, as opposed to stand-alone, neuroprotective effects, while reducing hemorrhagic transformation in ischemic stroke.

Unlocking the Potential of Stroke Blood Biomarkers: Early Diagnosis, Ischemic vs. Haemorrhagic Differentiation and Haemorrhagic Transformation Risk: A Comprehensive Review.

Stroke, a complex and heterogeneous disease, is a leading cause of morbidity and mortality worldwide. The timely therapeutic intervention significantly impacts patient outcomes, but early stroke diagnosis is challenging due to the lack of specific diagnostic biomarkers. This review critically examines the literature for potential biomarkers that may aid in early diagnosis, differentiation between ischemic and hemorrhagic stroke, and prediction of hemorrhagic transformation in ischemic stroke. After a thorough analysis, four promising biomarkers were identified: Antithrombin III (ATIII), fibrinogen, and ischemia-modified albumin (IMA) for diagnostic purposes; glial fibrillary acidic protein (GFAP), micro RNA 124-3p, and a panel of 11 metabolites for distinguishing between ischemic and hemorrhagic stroke; and matrix metalloproteinase-9 (MMP-9), s100b, and interleukin 33 for predicting hemorrhagic transformation. We propose a biomarker panel integrating these markers, each reflecting different pathophysiological stages of stroke, that could significantly improve stroke patients' early detection and treatment. Despite promising results, further research and validation are needed to demonstrate the clinical utility of this proposed panel for routine stroke treatment.

Hemorrhagic transformation of ischemic stroke in a patient with Fahr’s disease

BackgroundFahr’s disease is a very rare inherited neurodegenerative disorder characterized by diffuse and symetric intracranial calcification of the bilateral basal ganglia and cerebellum. Although the disease is slowly progressive, several acute forms have been described. We would like to present a very rare case of Fahr’s disease with an ischemic stroke and its hemorrhagic transformation.Case presentationA 70-year-old woman presented to our emergency department with rapid cognitive decline, dysarthria and right limb weakness. Cranial computed tomography showed diffuse and symmetric hyperdense areas at the level of the bilateral dentate nuclei of cerebellar hemispheres and basal ganglia, suggestive of calcification consistent with Fahr's disease on a background of thyroidectomy history, and effacement in the left caudate region. The patient was admitted to the intensive care unit with suspected left cerebral ischemic stroke. Because of clinical deterioration with increasing drowsiness and right hemiplegia, a control computed tomography scan was performed. Upon detection of a 6 * 8 cm lesion corresponding to an intracerebral hematoma in the left temporoparietal area with intraventricular component, she underwent surgery. The patient did not become hemodynamically stable and died on post-operative day 3.ConclusionsThe calcium deposits in the walls of the cerebral vessels in Fahr’s disease may exacerbate inflammatory processes leading to disruption of the blood-brain barrier. In addition, peripheral blood extravasation into the disrupted blood brain barrier due to ischemic stroke may lead to hemorrhagic transformation.

Abstract 295: Anti-coagulation Choice in Patient with Atrial Fibrillation and Acute Ischemic Stroke

To prevent embolic stroke, patients with atrial fibrillation are risk stratified, and started on anticoagulation accordingly. This poses a management challenge when these patients present to the hospital with ischemic stroke. Often, anticoagulation is held due to risk of hemorrhagic conversion. The optimal choice of anticoagulation to reduce the risk of hemorrhagic transformation of ischemic stroke in patients with atrial fibrillation is poorly studied. This study evaluates the risk of hemorrhagic conversion between different anticoagulation therapies in patients with atrial fibrillation who present to the hospital for ischemic stroke. Retrospectively, 8,596 acute stroke patients with atrial fibrillation were studied. Patients were subdivided into three groups depending on their home anticoagulation: apixaban, rivaroxaban, and warfarin. Binary logistic regression was used to predict the likelihood of an outcome for a binary variable. The outcome measured in this study was incidents of hemorrhagic conversion and ICU admission. Patients who were taking apixaban and rivaroxaban were less likely to have hemorrhagic conversion compared to the warfarin group (Odds Ratio 0.608 [0.467, 0.493], p<0.0001 and 0.734 [0.054, 0.493] p=0.0471). There was no significant difference when comparing the incidence of hemorrhagic conversion between apixaban and rivaroxaban. Patients who were taking apixaban were 0.787 times as likely to be admitted to the ICU compared to rivaroxaban group [0.679, 0.911], p=0.0003. Patient who were taking apixaban were 0.758 times as likely to be admitted to the ICU compare to Warfarin [0.662, 0.868], p= <0.0001. This study suggests that hemorrhagic conversion risk is higher in the warfarin group compared to apixaban and rivaroxaban groups. Additionally, patients who were taking apixaban experienced significantly less ICU admissions. Because this is a retrospective study, we cannot conclude a causative relationship. However, based on the results of this study, it is reasonable to consider alternatives to warfarin (such as apixaban and rivaroxaban) in patients with atrial fibrillation who present with ischemic stroke.

MiR-671-5p Upregulation Attenuates Blood–Brain Barrier Disruption in the Ischemia Stroke Model Via the NF-кB/MMP-9 Signaling Pathway

Blood-brain barrier (BBB) disruption can induce further hemorrhagic transformation in ischemic stroke (IS). miR-671-5p, a micro-RNA, is abundant in the cortex of mammalian brains. Herein, we investigated the roles and potential mechanisms for the effects of miR-671-5p on BBB permeability in IS. Results showed that miR-671-5p levels were significantly downregulated in the cerebral cortex of middle cerebral artery occlusion/reperfusion (MCAO/R) C57/BL6 mice in vivo. miR-671-5p agomir administration via right intracerebroventricular injection significantly reduced infarct volume, improved neurological deficits, the axon of neurons and nerve fiber, attenuated cell injury and apoptosis, as well as reduced BBB permeability in MCAO/R mice. Treatment with miR-671-5p agomir alleviated tight junction proteins degradation, including claudin, occludin, and ZO-1 in MCAO/R mice, and these effects were reversed following NF-κB overexpression. Bend.3 brain endothelial cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) treatment in vivo, and then miR-671-5p agomir was transfected into the cells. This resulted in reduction of cytotoxicity, improved cell viability, trans-endothelial electrical resistance, reduced fluorescein sodium permeability, and inhibited tight junction degradation in Bend.3 OGD/R cells. However, these effects were reversed following NF-κB overexpression. These results demonstrated that upregulation of miR-671-5p in IS models in vivo and in vitro alleviated BBB permeability by targeting NF-κB/MMP-9. In summary, miR-671-5p is a potential therapeutic target for protecting BBB permeability in IS to minimize cerebral hemorrhage transformation.

Abstract Number: LBA16 Does Intracranial Hemorrhage Associated with Tenecteplase Occur Exclusively Within the Stroke Burden?

Introduction As IV tenecteplase (TNK) is becoming an alternative to IV alteplase in acute ischemic stroke (AIS), establishing the incidence of intracranial hemorrhage (ICH) complications is important. Given the higher fibrin specificity of TNK as compared to alteplase, our aim was to distinguish hemorrhage within the stroke burden versus spontaneous ICH in patients with AIS with TNK‐associated ICH. Methods Retrospective chart review of patients presenting from February 2020 to January 2022 with anterior circulation AIS to our comprehensive stroke center who received TNK was performed to evaluate for associated ICH. ECASS‐3 criteria was used to define hemorrhagic transformation and ICH score was used for primary, spontaneous ICH. Fisher exact test statistic was used to evaluate for significant differences in ASPECTS score, medium versus versus large vessel occlusion, angiographic recanalization, IV eptifibatide use, pre‐morbid antiplatelet use, and association with symptomatic versus asymptomatic hemorrhage. A benchmark less than 5% symptomatic ICH incidence was set based on historical alteplase rates within our network. Social science statistics software was used for data analysis. Results Out of 77 subjects who received TNK, 20.7% (n = 16) developed ICH, 9.1% (n = 7) of which were symptomatic ICH with a temporally‐related increase in NIHSS of at least 4 or greater. Seven subjects (43.75%) were male. Mean age was 73.38 (95% CI 65.92, 80.83). Median initial NIHSS was 16, 95% CI [11.74, 21.51]. Median ASPECTS was 9, 95% CI [8.74, 9.89]. Two subjects developed spontaneous, primary ICH (n = 1 symptomatic ICH, n = 1 non‐symptomatic ICH) in the absence of hemorrhagic transformation of ischemic stroke. No significant difference between subjects with asymptomatic hemorrhage versus symptomatic hemorrhage was found when comparing ASPECTS > = 7 versus < 7 (Fisher value = 1), angiographic recanalization (Fisher value = 1), use of IV eptifibatide (Fisher value = 1), pre‐morbid antiplatelet use (Fisher value = 0.13), or medium vessel occlusion (Fisher value = ‐0.63). Conclusions Expected rates of hemorrhagic transformation were higher in tenecteplase than our historical benchmark rate for alteplase. Spontaneous hemorrhage unrelated to ischemic stroke area were seen in 2 subjects without known hematological disorders. Larger, prospective studies are needed to validate safety of tenecteplase in real world settings.

Unsupervised Deep Learning for Stroke Lesion Segmentation on Follow-up CT Based on Generative Adversarial Networks.

Supervised deep learning is the state-of-the-art method for stroke lesion segmentation on NCCT. Supervised methods require manual lesion annotations for model development, while unsupervised deep learning methods such as generative adversarial networks do not. The aim of this study was to develop and evaluate a generative adversarial network to segment infarct and hemorrhagic stroke lesions on follow-up NCCT scans. Training data consisted of 820 patients with baseline and follow-up NCCT from 3 Dutch acute ischemic stroke trials. A generative adversarial network was optimized to transform a follow-up scan with a lesion to a generated baseline scan without a lesion by generating a difference map that was subtracted from the follow-up scan. The generated difference map was used to automatically extract lesion segmentations. Segmentation of primary hemorrhagic lesions, hemorrhagic transformation of ischemic stroke, and 24-hour and 1-week follow-up infarct lesions were evaluated relative to expert annotations with the Dice similarity coefficient, Bland-Altman analysis, and intraclass correlation coefficient. The median Dice similarity coefficient was 0.31 (interquartile range, 0.08-0.59) and 0.59 (interquartile range, 0.29-0.74) for the 24-hour and 1-week infarct lesions, respectively. A much lower Dice similarity coefficient was measured for hemorrhagic transformation (median, 0.02; interquartile range, 0-0.14) and primary hemorrhage lesions (median, 0.08; interquartile range, 0.01-0.35). Predicted lesion volume and the intraclass correlation coefficient were good for the 24-hour (bias, 3 mL; limits of agreement, -64-59 mL; intraclass correlation coefficient, 0.83; 95% CI, 0.78-0.88) and excellent for the 1-week (bias, -4 m; limits of agreement,-66-58 mL; intraclass correlation coefficient, 0.90; 95% CI, 0.83-0.93) follow-up infarct lesions. An unsupervised generative adversarial network can be used to obtain automated infarct lesion segmentations with a moderate Dice similarity coefficient and good volumetric correspondence.

Ca lâm sàng: Cơn cường giao cảm kịch phát sau đột quỵ nhồi máu não cấp

Background: Paroxysmal sympathetic hyperactivity (PSH) may occur after acute ischemic stroke. The clinical presentation of PSH results from increased sympathetic overdrive, including transient paroxysms of tachycardia, hypertension, hyperventilation, hyperthermia, dystonic posturing, and excessive sweating. The exact pathophysiology of PSH, however, remains unclear, and no definitive treatment is available. Case presentation: Herein, the authors report a case of PSH in a female patient who experienced an acute ischemic stroke, for which a good clinical outcome. An 88-year-old woman was admitted to 108 Military Central Hospital. She had a Glasgow Coma Scale (GCS) score of 9 (M4V2E3), right hemiplegia, NIHSS score of 29. At admission, computed tomography revealed a reduction in the density of the left hemisphere, the blood supply area of the left middle cerebral artery (ASPECT 2 points). 12 days after ischemic stroke, the patient was diagnosed with PSH based on PSH-AM score (19 points). Morphine, gabapentin, and baclofen were administered; the drug effect was sufficient. 17 days poststroke, the patient gradually recovered from the adrenergic symptoms of PSH, and head computed tomography performed 12 days after stroke revealed improvement. Ultimately, the patient recovered with GCS score of 12 (M5V3E4), NIHSS score of 16, and lived at home. Conclusion: The outcome of the present case demonstrates that PSH can be reversed if it is identified early and before it becomes irreversible, that is, post the development of hypoxic encephalopathy or hemorrhagic transformation in ischemic stroke. * Keywords: Paroxysmal sympathetic hyperactivity; Acute ischemic stroke.

Thrombolytic tPA-induced hemorrhagic transformation of ischemic stroke is mediated by PKCβ phosphorylation of occludin

AbstractThe current standard of care for moderate to severe ischemic stroke is thrombolytic therapy with tissue plasminogen activator (tPA). Treatment with tPA can significantly improve neurologic outcomes; however, thrombolytic therapy is associated with an increased risk of intracerebral hemorrhage (ICH). The risk of hemorrhage significantly limits the use of thrombolytic therapy, and identifying pathways induced by tPA that increase this risk could provide new therapeutic options to extend thrombolytic therapy to a wider patient population. Here, we investigate the role of protein kinase Cβ (PKCβ) phosphorylation of the tight junction protein occludin during ischemic stroke and its role in cerebrovascular permeability. We show that activation of this pathway by tPA is associated with an increased risk of ICH. Middle cerebral artery occlusion (MCAO) increased phosphorylation of occludin serine 490 (S490) in the ischemic penumbra in a tPA-dependent manner, as tPA−/− mice were significantly protected from MCAO-induced occludin phosphorylation. Intraventricular injection of tPA in the absence of ischemia was sufficient to induce occludin phosphorylation and vascular permeability in a PKCβ-dependent manner. Blocking occludin phosphorylation, either by targeted expression of a non-phosphorylatable form of occludin (S490A) or by pharmacologic inhibition of PKCβ, reduced MCAO-induced permeability and improved functional outcome. Furthermore, inhibiting PKCβ after MCAO prevented ICH associated with delayed thrombolysis. These results show that PKCβ phosphorylation of occludin is a downstream mediator of tPA-induced cerebrovascular permeability and suggest that PKCβ inhibitors could improve stroke outcome and prevent ICH associated with delayed thrombolysis, potentially extending the window for thrombolytic therapy in stroke.

An alternative reduced dose regimen of ticagrelor for neuroendovascular patients.

There is a growing use of ticagrelor in patients undergoing neuroendovascular procedures, especially those who demonstrate clopidogrel resistance. While multiple dosages are studied in the cardiology literature, the optimal dose for patients with neurological pathology has yet to be established. Here, we describe a single center experience involving 39 patients who underwent neuroendovascular procedures that then received an adjusted lower dose of ticagrelor. A retrospective chart review was performed between 2013 and 2017 for patients on dual anti-platelet therapy (DAPT) for either cervical or intracranial vascular pathologies, as well as stenting of the neurovasculature, including carotid arteries. Patients were placed on ticagrelor if their measured P2Y12 reaction units (PRU) responses to clopidogrel were outside the expected range in our center using the VerifyNow™ P2Y12 test. All patients were maintained on a dose of 45mg twice daily except for one patient who received 22.5mg twice daily. Responsiveness to ticagrelor were measured utilizing the VerifyNow™ P2Y12 test. The mean number of days for follow-up post treatment initiation was 532days. A total of 39 patients were included in the analysis. Of these, 8 patients (21%) received implantation of intracranial stents (5 patients received pipeline embolization devices, 1 patient received stent-assisted coiling, and 2 patients received intracranial stents for atherosclerotic disease). Fourteen patients (35%) received carotid angioplasty and stenting. Seventeen patients (44%) did not receive permanent implantation of a stent. All patients on the lower dose ticagrelor of 45mg twice daily achieved responsiveness (i.e., PRU < 194). Hemorrhagic transformation of ischemic stroke occurred in one patient (2.5%). No other hemorrhagic complications were encountered. No thromboembolic events were recorded aside from one patient (2.5%) with intracranial atherosclerotic disease who had an ischemic event. A lower dose of ticagrelor (45mg twice daily) appears to be safe and effective in this small cohort of patients who are resistant to clopidogrel per P2Y12 testing and who have increased risk of ischemic or hemorrhagic strokes due to neurovascular pathologies and implants. Further randomized studies are required to confirm these findings.

GLP-1R Agonist Exendin-4 Protects Against Hemorrhagic Transformation Induced by rtPA After Ischemic Stroke via the Wnt/β-Catenin Signaling Pathway

Tissue plasminogen activator (tPA) is recommended by the FDA to dissolve intravascular clots after acute ischemic stroke (AIS). However, it may contribute to hemorrhagic transformation (HT). The Wnt/β-catenin signaling pathway plays an important role in regulating the blood–brain barrier (BBB) formation in the central nervous system. We explored whether glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (EX-4) reduces the risk of HT after rtPA treatment via the Wnt/β-catenin pathway by using a rat transient middle cerebral artery occlusion (MCAO) model in vivo and an oxygen–glucose deprivation plus reoxygenation (OGD/R) model in vitro. Our results showed that EX-4 attenuated neurological deficits, brain edema, infarct volume, BBB disruption, and rtPA-induced HT in ischemic stroke. EX-4 suppressed the production of ROS and the activation of MMP-9 to protect the integrity of the BBB by activating the Wnt/β-catenin signaling pathway. PRI-724, a selective inhibitor of β-catenin, was able to reverse the therapeutic effect of EX-4 in vivo and in vitro. Therefore, our results indicate that the GLP-1R agonist may be a potential therapeutic agent to decrease the risk of rtPA-induced HT after ischemic stroke via the Wnt/β-catenin signaling pathway.

Multimodal imaging of hemorrhagic transformation biomarkers in an ischemic stroke model.

Hemorrhagic transformation of ischemic stroke has devastating consequences, with high mortality and poor functional outcomes. Animal models of ischemic stroke also demonstrate the potential for hemorrhagic transformation, which complicates biochemical characterization, treatment studies, and hinders poststroke functional outcomes in affected subjects. The incidence of hemorrhagic transformation of ischemic stroke in animal model research is not commonly reported. The postmortem brain of such cases presents a complex milieu of biomarkers due to the presence of healthy cells, regions of varying degrees of ischemia, dead and dying cells, dysregulated metabolites, and blood components (especially reactive Fe species released from lysed erythrocytes). To improve the characterization of hemorrhage biomarkers on an ischemic stroke background, we have employed a combination of histology, X-ray fluorescence imaging (XFI), and Fourier transform infrared (FTIR) spectroscopic imaging to assess 122 photothrombotic (ischemic) stroke brains. Rapid freezing preserves brain biomarkers in situ and minimizes metabolic artifacts due to postmortem ischemia. Analysis revealed that 25% of the photothrombotic models had clear signs of hemorrhagic transformation. The XFI and FTIR metabolites provided a quantitative method to differentiate key metabolic regions in these models. Across all hemorrhage cases, it was possible to consistently differentiate otherwise healthy tissue from other metabolically distinct regions, including the ischemic infarct, the ischemic penumbra, blood vessels, sites of hemorrhage, and a region surrounding the hemorrhage core that contained elevated lipid oxidation. Chemical speciation of deposited Fe demonstrates the presence of heme-Fe and accumulation of ferritin.

Abstract TP148: An Alternative Reduced Dose Regimen Of Ticagrelor For Neuroendovascular Patients

Background: There is a growing use of Ticagrelor in patients undergoing neuroendovascular procedures, especially those who demonstrate Clopidogrel resistance. While multiple dosages are studied in the cardiology literature, the optimal dose for patients with neurological pathology has yet to be established. Here we describe a single center experience involving 39 patients who underwent neuroendovascular procedures that then received an adjusted lower dose of Ticagrelor Methods: A retrospective chart review was performed between 2013 and 2017 for patients on dual antiplatelet therapy (DAPT) for either cervical or intracranial vascular pathologies, as well as stenting of the neurovasculature, including carotid arteries. Patients were placed on Ticagrelor if their measured PRU responses to Clopidogrel were outside the expected range in our center using the P2Y12 test. All patients were maintained on a dose of 45mg BID except for one patient who received 22.5 mg BID. Responsiveness to Ticagrelor were measured utilizing the P2Y12 test Results: The mean number of days for follow up post treatment initiation was 532 days. A total of 39 patients were included in the analysis. Of these, 8 patients (21%) received implantation of intracranial stents (5 patients received pipeline embolization devices, 1 patient received stent assisted coiling, and 2 patients received intra-cranial stents for atherosclerotic disease). Fourteen patients (35%) received carotid angioplasty and stenting. Seventeen patients (44%) did not receive permanent implantation of a stent. All patients on the lower dose Ticagrelor of mg BID achieved responsiveness per the P2Y12 test. Hemorrhagic transformation of ischemic stroke occurred in one patient (2.5%). No other hemorrhagic complications were encountered. No thromboembolic events were recorded aside from one patient (2.5%) with intracranial atherosclerotic disease who had an ischemic event Conclusion: A lower dose of Ticagrelor (45 mg BID) appears to be a safe and effective in this small cohort of patients who are resistant to Clopidogrel per P2Y12 testing and who have increased risk of ischemic or hemorrhagic strokes due to neurovascular pathologies and implants. Further randomized studies are required to confirm these findings