Metabolomic changes in adults with status epilepticus: A human case-control study.

OBJECTIVE: Status epilepticus (SE) is a life-threatening prolonged epileptic seizure that affects ~40 per 100 000 people yearly worldwide. The persistence of seizures may lead to excitotoxic processes, neuronal loss, and neuroinflammation, resulting in long-term neurocognitive and functional disabilities. A better understanding of the pathophysiological mechanisms underlying SE consequences is crucial for improving SE management and preventing secondary neuronal injury. METHODS: We conducted a comprehensive untargeted metabolomic analysis, using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), on plasma and cerebrospinal fluid (CSF) samples from 78 adult patients with SE and 107 control patients without SE, including 29 with CSF for both groups. The metabolomic fingerprints were compared between patients with SE and controls. Metabolites with differences in relative abundances that could not be attributed to treatment or nutrition provided in the intensive care unit were isolated. Enrichment analysis was performed on these metabolites to identify the most affected pathways. RESULTS: We identified 76 metabolites in the plasma and 37 in the CSF that exhibited differential expression in patients with SE compared to controls. The enrichment analysis revealed that metabolic dysregulations in patients with SE affected primarily amino acid metabolism (including glutamate, alanine, tryptophan, glycine, and serine metabolism), pyrimidine metabolism, and lipid homeostasis. Specifically, patients with SE had elevated levels of pyruvate, quinolinic acid, and keto butyric acid levels, along with lower levels of arginine, N-acetylaspartylglutamate (NAAG), tryptophan, uracil, and uridine. The tryptophan kynurenine pathway was identified as the most significantly altered in SE, resulting in the overproduction of quinolinic acid, an N-methyl-d-aspartate (NMDA) receptor agonist with pro-inflammatory properties. SIGNIFICANCE: This study has identified several pathways that may play pivotal roles in SE consequences, such as the tryptophan kynurenine pathway. These findings offer novel perspectives for the development of neuroprotective therapeutics.

Intravenous abciximab as a rescue therapy for immediate reocclusion after successful mechanical thrombectomy in acute ischemic stroke patients.

Immediate reocclusion after mechanical thrombectomy (MT) for acute ischemic stroke (AIS) is a rare but devastating condition associated with poor functional outcome. The aim of this study was to gain insights into the mechanisms underlying immediate reocclusion, and to evaluate the efficacy and safety of the glycoprotein IIb/IIIa antagonist abciximab, for its treatment. Clinical data were collected from April 2015 to April 2019 in a monocentric prospective registry of AIS patients treated by MT. All patients with immediate reocclusion were retrospectively selected and subdivided into 2 groups according to abciximab treatment status. In vitro, the separate and combined effects of abciximab and alteplase on clot formation in whole blood under flow conditions were further investigated in microfluidic chambers. From 929 MT-treated patients, 21 had post-MT immediate reocclusion. Abciximab treatment in reocclusion patients (n = 10) led to higher rate of final recanalization (p < .001) while it did not increase bleeding complications. Flow chamber experiments revealed that, in contrast to alteplase, abciximab efficiently limits thrombus accretion from flowing blood by blocking platelet aggregation. Our results underscore a key role for platelet aggregation and the potential of Glycoprotein IIb/IIIa antagonists as a rescue therapy in post-MT immediate reocclusion.

Glenzocimab does not impact glycoprotein VI-dependent inflammatory haemostasis.

Not available.

Protective Effect of ApoA1 (Apolipoprotein A1)-Milano in a Rat Model of Large Vessel Occlusion Stroke.

Background and Purpose- Previous experimental studies found that the infusion of human purified nascent HDL (high-density lipoprotein) significantly reduced infarct volume and hemorrhagic transformation rate by decreasing neutrophil recruitment. ApoA1-M (apolipoprotein A1-Milano) is a natural variant of human ApoA1 that confers protection against atherosclerosis. Recombinant ApoA1-M has been formulated as a complex with phospholipids to mimic the properties of nascent HDL. The aim of this study was to assess the impact of intravenous ApoA1-M in a transient middle cerebral artery occlusion stroke model in rats. Methods- In a first experiment, rats were subjected to 120-minute transient middle cerebral artery occlusion and intravenous ApoA1-M was infused immediately or 4 hours after occlusion. In a second experiment, rats were subjected to 240-minute transient middle cerebral artery occlusion and intravenous ApoA1-M was infused with or without recombinant tPA (tissue-type plasminogen activator) immediately after recanalization. Primary outcome criteria were the infarct volume and hemorrhagic transformation rate measured at 24 hours. Platelets, coagulation, and neutrophil activation biomarkers were measured in brain homogenates and plasma. Additional in vitro experiments studied the effects of ApoA1-M on platelet aggregation and platelet-neutrophil interactions. Results- The infusion of ApoA1-M immediately or 4 hours after 120-minute transient middle cerebral artery occlusion significantly reduced the infarct volume compared with saline (P=0.034 and P=0.036, respectively). Compared with tPA alone, co-administration of ApoA1-M and tPA showed similar rates of hemorrhagic transformation. ApoA1-M had no significant inhibition effect on neutrophil activation biomarkers. Platelet activation was slightly decreased in rats treated with ApoA1-M compared with saline. In vitro, the incubation of human and rat platelet-rich plasma with ApoA1-M significantly reduced ADP-induced platelet aggregation (P=0.001 and P=0.02, respectively). Conclusions- ApoA1-Milano significantly decreased the infarct volume through an inhibition of platelet aggregation but did not reduce hemorrhagic transformation and neutrophils activation as expected after previous experimental studies with nascent HDL. Visual Overview- An online visual overview is available for this article.

DNA Content in Ischemic Stroke Thrombi Can Help Identify Cardioembolic Strokes Among Strokes of Undetermined Cause.

BACKGROUND AND PURPOSE: Identification of acute ischemic stroke (AIS) cause is crucial for guidance of secondary prevention. Previous studies have yielded inconsistent results regarding possible correlations between AIS cause and thrombus composition, as assessed by semiquantitative histological analysis. Here, we performed a correlation analysis between AIS cause and AIS thrombus cellular composition and content, as assessed using quantitative biochemical assays. METHODS: Homogenates of 250 patients with AIS thrombi were prepared by mechanical grinding. Platelet, red blood cell, and leukocyte content of AIS thrombi were estimated by quantification of GP (glycoprotein) VI, heme, and DNA in thrombus homogenates. AIS cause was defined as cardioembolic, noncardioembolic, or embolic stroke of undetermined source, according to the TOAST classification (Trial of ORG 10172 in Acute Stroke Treatment). RESULTS: Cardioembolic thrombi were richer in DNA (35.8 versus 13.8 ng/mg, P<0.001) and poorer in GPVI (0.104 versus 0.117 ng/mg, P=0.045) than noncardioembolic ones. The area under the receiver operating characteristic curve of DNA content to discriminate cardioembolic thrombi from noncardioembolic was 0.72 (95% CI, 0.63-0.81). With a threshold of 44.7 ng DNA/mg thrombus, 47% of thrombi from undetermined cause would be classified as cardioembolic with a specificity of 90%. CONCLUSIONS: Thrombus DNA content may provide an accurate biomarker for identification of cardioembolic thrombi in patients with AIS with embolic stroke of undetermined source. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03268668.

Intracranial Extension of Extracranial Vertebral Dissection Is Associated With an Increased Risk of Ischemic Events.

Background and Purpose- Intracranial artery dissection can eventually lead to subarachnoid or intracerebral hemorrhage. Little is known about the clinical features and risks associated with extracranial vertebral artery dissection that extends intracranially. The clinical and imaging characteristics of extracranial vertebral artery dissection (eVAD) with (e+iVAD) or without (eVAD) intracranial extension were analyzed. Methods- The frequency of ischemic events, including ischemic strokes and transient ischemic attacks, was compared between e+iVAD and eVAD patients from a monocentric cohort study. Results- Among 328 patients with cervical artery dissection, vertebral artery dissection was diagnosed in 153 individuals. Twenty-nine patients had e+iVAD (19%) and 124 patients had only eVAD (81%). Cardiovascular risk factors did not differ between these 2 groups, but ischemic events were more frequent in patients with e+iVAD than in patients with eVAD (86% versus 48%, P=0.0002). Subarachnoid hemorrhage occurred in 1 patient with e+iVAD and in 9 with eVAD (6% versus 3%, P=0.53). Intracranial extension was an independent factor associated with ischemic stroke at admission (odds ratio, 6.43; 95% CI, -1.96 to 21.08; P=0.002) after adjustment for cardiovascular risk factors and imaging findings. Conclusions- In a large cohort of patients with vertebral artery dissection, intracranial extension of the vessel dissection appears associated with an increased risk of ischemic stroke.

Thrombus Neutrophil Extracellular Traps Content Impair tPA-Induced Thrombolysis in Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Neutrophil Extracellular Traps (NETs) are DNA extracellular networks decorated with histones and granular proteins produced by activated neutrophils. NETs have been identified as major triggers and structural factors of thrombosis. A recent study designated extracellular DNA threads from NETs as a potential therapeutic target for improving tissue-type plasminogen activator (tPA)-induced thrombolysis in acute coronary syndrome. The aim of this study was to assess the presence of NETs in thrombi retrieved during endovascular therapy in patients with acute ischemic stroke (AIS) and their impact on tPA-induced thrombolysis. METHODS: We analyzed thrombi from 108 AIS patients treated with endovascular therapy. Thrombi were characterized by hematoxylin/eosin staining, immunostaining, and ex vivo enzymatic assay. Additionally, we assessed ex vivo the impact of deoxyribonuclease 1 (DNAse 1) on thrombolysis of AIS thrombi. RESULTS: Histological analysis revealed that NETs contributed to the composition of all AIS thrombi especially in their outer layers. Quantitative measurement of thrombus NETs content was not associated with clinical outcome or AIS pathogenesis but correlated significantly with endovascular therapy procedure length and device number of passes. Ex vivo, recombinant DNAse 1 accelerated tPA-induced thrombolysis, whereas DNAse 1 alone was ineffective. CONCLUSIONS: This study suggests that thrombus NETs content may be responsible for reperfusion resistance, including mechanical or pharmacological approaches with intravenous tPA, irrespectively of their etiology. The efficacy of a strategy involving an administration of DNAse 1 in addition to tPA should be explored in the setting of AIS. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02907736.

Exacerbation of Thromboinflammation by Hyperglycemia Precipitates Cerebral Infarct Growth and Hemorrhagic Transformation.

BACKGROUND AND PURPOSE: Admission hyperglycemia is associated with a poor outcome in acute ischemic stroke. How hyperglycemia impacts the pathophysiology of acute ischemic stroke remains largely unknown. We investigated how preexisting hyperglycemia increases ischemia/reperfusion cerebral injury. METHODS: Normoglycemic and streptozotocin-treated hyperglycemic rats were subjected to transient middle cerebral artery occlusion. Infarct growth and brain perfusion were assessed by magnetic resonance imaging. Markers of platelet, coagulation, and neutrophil activation were measured in brain homogenates and plasma. Downstream microvascular thromboinflammation (DMT) was investigated by intravital microscopy. RESULTS: Hyperglycemic rats had an increased infarct volume with an increased blood-brain barrier disruption and hemorrhagic transformation rate compared with normoglycemic rats. Magnetic resonance imaging scans revealed that hyperglycemia enhanced and accelerated lesion growth and was associated with hemorrhagic transformation originating from territories that were still not completely reperfused at 1 hour after middle cerebral artery recanalization. Intravital microscopy and analysis of brain homogenates showed that DMT began immediately after middle cerebral artery occlusion and was exacerbated by hyperglycemia. Measurement of plasma serotonin and matrix metalloproteinase-9 indicated that platelets and neutrophils were preactivated in hyperglycemic rats. Neutrophils from hyperglycemic diabetic patients showed increased adhesion to endothelial cells as compared with neutrophils from normoglycemic donors in flow chamber experiments. CONCLUSIONS: We show that hyperglycemia primes the thromboinflammatory cascade, thus, amplifying middle cerebral artery occlusion-induced DMT. DMT exacerbation in hyperglycemic rats impaired reperfusion and precipitated neurovascular damage, blood-brain barrier disruption, and hemorrhagic transformation. Our results designate DMT as a possible target for reduction of the deleterious impact of hyperglycemia in acute ischemic stroke.

Periodontitis in ischemic stroke: impact of Porphyromonas gingivalis on thrombus composition and ischemic stroke outcomes.

Background: Periodontitis is associated with an increased risk of ischemic stroke, but the mechanisms underlying this association remain unclear. Objectives: Our objective was to determine whether Porphyromonas gingivalis (Pg), a periodontal bacterium, could be detected within thrombus aspirates, modify thrombus composition, and endovascular therapy responses. Methods: The presence of Pg gingipain in 175 consecutive thrombi from patients with large vessel occlusion stroke enrolled in the multicenter research cohort compoCLOT was investigated by immunostaining. Thrombus blood cell composition according to gingipain status was analyzed in a subset of 63 patients. Results: Pg gingipain immunostaining was positive in 33.7% of thrombi (95% CI, 26.7%-40.8%). The percentage of near to complete reperfusion (modified Thrombolysis in Cerebral Infarction Score 2c/3) at the end of the procedure was lower in the Pgpos group than the Pgneg group (39.0% vs 57.8% respectively; adjusted odds ratio, 0.38; 95% CI, 0.19-0.77). At 3 months, 35.7% of patients in the Pgpos group had a favorable neurological outcome vs 49.5% in the Pgneg group (odds ratio, 0.65; 95% CI, 0.30-1.40). Quantitative analysis of a subset of 63 thrombi showed that neutrophil elastase content was significantly (P < .05) higher in Pgpos thrombi than in Pgneg thrombi. Conclusion: Our results indicate that intrathrombus Pg gingipain is associated with increased neutrophil content and resistance to endovascular therapy.

Neutrophil activation in patients treated with endovascular therapy is associated with unfavorable outcomes and mitigated by intravenous thrombolysis.

BACKGROUND: Accumulating evidence indicates that neutrophil activation (NA) contributes to microvascular thromboinflammation in acute ischemic stroke (AIS) due to a large vessel occlusion. Preclinical data have suggested that intravenous thrombolysis (IVT) before endovascular therapy (EVT) could dampen microvascular thromboinflammation. In this study we investigated the association between NA dynamics and stroke outcome, and the impact of IVT on NA in patients with AIS treated with EVT. METHODS: A single-center prospective study was carried out, including patients treated with EVT for whom three blood samples (before, within 1 hour, 24 hours post-EVT) were drawn to measure plasma myeloperoxidase (MPO) concentration as a marker of NA. Unfavorable outcome was defined as a modified Rankin score of 3-6 at 3 months. RESULTS: Between 2016 and 2020, 179 patients were included. The plasma MPO concentration peaked significantly 1 hour post-EVT (median increase 21.0 ng/mL (IQR -2.1-150)) and returned to pre-EVT baseline values 24 hours after EVT (median change from baseline -0.8 ng/mL (IQR -7.6-6.7)). This peak was strongly associated with unfavorable outcomes at 3 months (aOR 0.53 (95% CI 0.34 to 0.84), P=0.007). IVT before EVT abolished this 1 hour post-EVT MPO peak. Changes in plasma MPO concentration (baseline to 1 hour post-EVT) were associated with unfavorable outcomes only in patients not treated with IVT before EVT (aOR 0.54 (95% CI 0.33 to 0.88, P=0.013). However, we found no significant heterogeneity in the associations between changes in plasma MPO concentration and outcomes. CONCLUSIONS: A peak in plasma MPO concentration occurs early after EVT and is associated with unfavorable outcomes. IVT abolished the post-EVT MPO peak and may modulate the association between NA and outcomes.

Composition and Organization of Acute Ischemic Stroke Thrombus: A Wealth of Information for Future Thrombolytic Strategies.

During the last decade, significant progress has been made in understanding thrombus composition and organization in the setting of acute ischemic stroke (AIS). In particular, thrombus organization is now described as highly heterogeneous but with 2 preserved characteristics: the presence of (1) two distinct main types of areas in the core-red blood cell (RBC)-rich and platelet-rich areas in variable proportions in each thrombus-and (2) an external shell surrounding the core composed exclusively of platelet-rich areas. In contrast to RBC-rich areas, platelet-rich areas are highly complex and are mainly responsible for the thrombolysis resistance of these thrombi for the following reasons: the presence of platelet-derived fibrinolysis inhibitors in large amounts, modifications of the fibrin network structure resistant to the tissue plasminogen activator (tPA)-induced fibrinolysis, and the presence of non-fibrin extracellular components, such as von Willebrand factor (vWF) multimers and neutrophil extracellular traps. From these studies, new therapeutic avenues are in development to increase the fibrinolytic efficacy of intravenous (IV) tPA-based therapy or to target non-fibrin thrombus components, such as platelet aggregates, vWF multimers, or the extracellular DNA network.

Impact of COVID-19 on thrombus composition and response to thrombolysis: Insights from a monocentric cohort population of COVID-19 patients with acute ischemic stroke.

BACKGROUND: Resistance to fibrinolysis, levels of procoagulant/antifibrinolytic neutrophil extracellular traps (NETs), and the severity of acute ischemic stroke (AIS) are increased by COVID-19. Whether NETs are components of AIS thrombi from COVID-19 patients and whether COVID-19 impacts the susceptibility of these thrombi to thrombolytic treatments remain unknown, however. OBJECTIVES: We aimed to characterize AIS thrombi from COVID-19 patients by immunohistology and to compare their response to thrombolysis to that of AIS thrombi from non-COVID-19 patients. PATIENTS/METHODS: For this monocentric cohort study, 14 thrombi from COVID-19 AIS patients and 16 thrombi from non-COVID-19 patients, all recovered by endovascular therapy, were analyzed by immunohistology or subjected to ex vivo thrombolysis by tissue-type plasminogen (tPA)/plasminogen. RESULTS: COVID-19 AIS thrombi were rich in neutrophils and contained NETs, but not spike protein. Thrombolysis assays revealed a mean resistance profile to tPA/plasminogen of COVID-19 AIS thrombi similar to that of non-COVID-19 AIS thrombi. The addition of DNase 1 successfully improved thrombolysis by potentiating fibrinolysis irrespective of COVID-19 status. Levels of neutrophil, NETs, and platelet markers in lysis supernatants were comparable between AIS thrombi from non-COVID-19 and COVID-19 patients. CONCLUSIONS: These results show that COVID-19 does not impact NETs content or worsen fibrinolysis resistance of AIS thrombi, a therapeutic hurdle that could be overcome by DNase 1 even in the context of SARS-CoV-2 infection.

High thrombus platelet content is associated with a lower rate of first pass effect in stroke treated by endovascular therapy.

Background and purpose: First pass effect (FPE), the occurrence of complete reperfusion after one pass with no rescue attempt during endovascular therapy (EVT), is associated with the best clinical outcome after an acute ischemic stroke (AIS). Previous studies evaluating FPE occurrence according to EVT technical strategies, occlusion locations, or thrombus composition have provided controversial results. Here, we performed a correlation analysis between FPE occurrence and AIS thrombus cellular composition, as assessed using quantitative biochemical assays. Patients and methods: Homogenates of AIS thrombi from 250 patients were prepared by mechanical grinding. Platelet, red blood cell (RBC), and leukocyte contents of AIS thrombi were respectively estimated by quantification of GP (glycoprotein) VI, heme, and DNA in thrombus homogenates. FPE was defined as a modified Thrombolysis in Cerebral Infraction (mTICI) score of 2C or 3 after a single EVT device pass. Results: AIS thrombi successfully removed after a single pass were poorer in GPVI (0.098 ± 0.023 vs 0.111 ± 0.024 ng/mg, p < 0.001) compared to those whose removal had required several passes. GPVI content was also significantly associated with a higher number of device passes and a longer procedure time. No such significant correlation was found with DNA and heme content. Discussion and conclusion: Thrombus platelet content may hamper thrombus removal by EVT. This result suggests that adjunctive therapies or functionalization of retrieval devices targeting platelets may improve EVT efficacy.

Carotid webs in large vessel occlusion stroke: Clinical, radiological and thrombus histopathological findings.

BACKGROUND: Carotid webs are an under-recognized embolic source in patients with cryptogenic stroke. Limited resources currently exist to assist clinicians in stroke prevention for patients with symptomatic carotid webs (SCW). We aimed at analysing the clinical, radiological and procedural features of stroke patients with SCW undergoing endovascular thrombectomy (EVT), and to describe the histopathological composition of their occlusive thrombi. METHODS: In a single-center observational study on consecutive patients with ischemic stroke treated by EVT, carotid web was defined symptomatic when it was ipsilateral to the ischemic lesion in a patient classified with stroke of otherwise undetermined etiology. Clinical, radiological and procedural data of patients with SCW were evaluated. Histopathological examination of the retrieved thrombi was performed. RESULTS: Out of 1430 patients with large vessel occlusion stroke treated by EVT, 11(0.7%) were found to have a SCW. Patients with SCW had a median age of 47 years old (IQR 38-50), they were prevalently women (55%), mostly of African ethnicity (91%). Each of the 11 patients achieved successful angiographic reperfusion (mTICI 2b-3) after EVT. For secondary prevention, elective endovascular carotid stenting was performed in 5 (55%) patients, while 1 (9%) was treated by surgical endoarterectomy. Histological analysis of the retrieved thrombi performed in 4 patients showed a mixed composition with variable red blood cell content. CONCLUSIONS: EVT is feasible in large vessel occlusion stroke related to SCW. Procedures of carotid revascularization appear to be feasible therapeutic options for secondary prevention. The histopathological analysis of cerebral thrombi may provide new insights on stroke pathogenesis in patients with SCW.

A Novel Mouse Model for Cerebral Venous Sinus Thrombosis.

Cerebral venous sinus thrombosis (CVST) is an uncommon cause of stroke resulting in parenchymal injuries associated with heterogeneous clinical symptoms and prognosis. Therefore, an experimental animal model is required to further study underlying mechanisms involved in CVST. This study is aimed at developing a novel murine model suitable and relevant for evaluating injury patterns during CVST and studying its clinical aspects. CVST was achieved in C57BL/6J mice by autologous clot injection into the superior sagittal sinus (SSS) combined with bilateral ligation of external jugular veins. Clot was prepared ex vivo using thrombin before injection. On days 1 and 7 after CVST, SSS occlusion and associated-parenchymal lesions were monitored using different modalities: in vivo real-time intravital microscopy, magnetic resonance imaging (MRI), and immuno-histology. In addition, mice were subjected to a neurological sensory-motor evaluation. Thrombin-induced clot provided fibrin- and erythrocyte-rich thrombi that lead to reproducible SSS occlusion at day 1 after CVST induction. On day 7 post-CVST, venous occlusion monitoring (MRI, intravital microscopy) showed that initial injected-thrombus size did not significantly change demonstrating no early spontaneous recanalization. Microscopic histological analysis revealed that SSS occlusion resulted in brain edema, extensive fibrin-rich venular thrombotic occlusion, and ischemic and hemorrhagic lesions. Mice with CVST showed a significant lower neurological score on post-operative days 1 and 7, compared to the sham-operated group. We established a novel clinically CVST-relevant model with a persistent and reproducible SSS occlusion responsible for symptomatic ischemic and hemorrhagic lesions. This method provides a reliable model to study CVST physiopathology and evaluation of therapeutic new regimens.

NLRP3 Inflammasome Assembly in Neutrophils Is Supported by PAD4 and Promotes NETosis Under Sterile Conditions.

Neutrophil extracellular trap formation (NETosis) and the NLR family pyrin domain containing 3 (NLRP3) inflammasome assembly are associated with a similar spectrum of human disorders. While NETosis is known to be regulated by peptidylarginine deiminase 4 (PAD4), the role of the NLRP3 inflammasome in NETosis was not addressed. Here, we establish that under sterile conditions the cannonical NLRP3 inflammasome participates in NETosis. We show apoptosis-associated speck-like protein containing a CARD (ASC) speck assembly and caspase-1 cleavage in stimulated mouse neutrophils without LPS priming. PAD4 was needed for optimal NLRP3 inflammasome assembly by regulating NLRP3 and ASC protein levels post-transcriptionally. Genetic ablation of NLRP3 signaling resulted in impaired NET formation, because NLRP3 supported both nuclear envelope and plasma membrane rupture. Pharmacological inhibition of NLRP3 in either mouse or human neutrophils also diminished NETosis. Finally, NLRP3 deficiency resulted in a lower density of NETs in thrombi produced by a stenosis-induced mouse model of deep vein thrombosis. Altogether, our results indicate a PAD4-dependent formation of the NLRP3 inflammasome in neutrophils and implicate NLRP3 in NETosis under noninfectious conditions in vitro and in vivo.

Modeling Large Vessel Occlusion Stroke for the Evaluation of Endovascular Therapy According to Thrombus Composition.

More than 40% of endovascular therapy (EVT) fail to achieve complete reperfusion of the territory of the occluded artery in patients with acute ischemic stroke (AIS). Understanding factors influencing EVT could help overcome its limitations. Our objective was to study the impact of thrombus cell composition on EVT procedures, using a simulation system for modeling thrombus-induced large vessel occlusion (LVO) in flow conditions. In an open comparative trial, we analyzed the behavior of size-standardized platelet-rich and red blood cells (RBC)-rich thrombi during simulated stent retriever-mediated EVT procedures. Sixteen simulated EVT procedures were performed (8 RBC- vs. 8 platelet-rich thrombi). Platelet-rich thrombi were associated with a higher number of stent retriever passes (p = 0.03) and a longer procedure duration (p = 0.02) compared to RBC-rich thrombi. Conversely, RBC-rich thrombi released more embolic fragments than platelet-rich thrombi (p = 0.004). Both RBC-rich and platelet-rich thrombi underwent drastic compaction after being injected into the in vitro circulation model, and histologic analyses showed that these EVT-retrieved thrombi displayed features comparable to those previously observed in thrombi from patients with AIS patients having LVO, including a marked structural dichotomy between RBC- and platelet-rich areas. Our results show that the injection of in vitro-produced thrombi in artificial cerebrovascular arterial networks is suitable for testing recanalization efficacy and the risk of embolization of EVT devices and strategies in association with thrombus cell composition.

Selective inhibition of carboxypeptidase U may reduce microvascular thrombosis in rat experimental stroke.

BACKGROUND: Carboxypeptidase U (CPU, CPB2, TAFIa) is a potent attenuator of fibrinolysis. The inhibition of CPU is thus an interesting strategy for improving thrombolysis. OBJECTIVES: The time course of CPU generation and proCPU consumption were assessed in an experimental rat model of acute ischemic stroke (AIS). In addition, the effects of the selective CPU inhibitor AZD9684 on CPU kinetics, microvascular thrombosis (MT), and AIS outcome were evaluated. METHODS: Rats were subjected to transient middle cerebral artery occlusion (tMCAO) and received recombinant tissue-type plasminogen activator (tPA), a specific CPU inhibitor (AZD9684), combination therapy of tPA and AZD9684, or saline for 1 hour using a randomized treatment regime. CPU and proCPU levels were determined at five time points and assessed in light of outcome parameters (a.o.: infarct volume and fibrin[ogen] deposition as a measure for MT). RESULTS: Clear activation of the CPU system was observed after AIS induction, in both saline- and tPA-treated rats. Maximal CPU activities were observed at treatment cessation and were higher in tPA-treated animals compared to the saline group. Concomitant proCPU consumption was more pronounced in tPA-treated rats. AZD9684 suppressed the CPU activity and reduced fibrin(ogen) deposition, suggesting a reduction of MT. Nonetheless, a significant decrease in infarct volume was not observed. CONCLUSIONS: A pronounced activation of the CPU system was observed during tMCAO in rats. Selective inhibition of CPU with AZD9684 was able to reduce fibrin(ogen) deposition and brain edema, suggesting a reduction of MT but without a significant effect on final infarct volume.