Translational Stroke Research最新文献

Conventional rat models of thromboembolic stroke do not allow control of infarct size or spontaneous recanalization. We aimed to develop a novel rat thromboembolic stroke model that ensures highly reproducible infarct sizes and locations within the MCA territory and does not require arterial ligation. Twenty male Sprague-Dawley rats and two sham-operated rats were included. A microcatheter was navigated from the caudal ventral artery to the internal carotid artery using digital subtraction angiography. A blood clot (diameter, 0.86 mm; length, 3 mm) containing zirconium dioxide was advanced in the catheter. Fluoroscopy was performed at 1, 3, 6, and 24 h after stroke model creation, and TTC staining was conducted at 24 h. Neurological deficit scores were measured. In all embolized rats, the ACA and MCA bifurcation were selective. Median operating time was 6 min. The position of the radiopaque blood clot remained unchanged for 24 h after model creation in 19/20 rats. Median infarct volume was 242 mm³ (IQR, 239-262 mm³). We present a novel rat model of highly reproducible focal infarct in only the MCA territory. Fluoroscopy effectively identified any blood clot migration. This model could contribute to the development of new thrombolytic agents.

Cerebrovascular stroke patients exhibit an increased incidence of cardiac arrhythmias. The pathomechanisms underlying post-traumatic cardiac dysfunction include a surge of catecholamines and an increased systemic inflammatory response, but whether inflammasome activation contributes to cardiac dysfunction remains unexplored. Here, we used a mouse model of photothrombotic stroke (PTS) to investigate the role of inflammasome activation in post-stroke cardiac dysfunction by catecholamines and to evaluate the effectiveness of the inflammasome inhibitor IC100 on inflammasome activation. To evaluate functional electrophysiological changes in the heart by catecholamine treatment, we recorded action potential duration in excised zebrafish hearts with and without IC100 treatment. We show that PTS induced AIM2 inflammasome activation in atria and ventricles that was significantly reduced by administration of IC100. Injection of epinephrine into naïve mice induced a significant increase in AIM2, IL-1b and caspase-8 in atria. Treatment of excised zebrafish hearts with epinephrine shortened the action potential duration and this shortening that was reduced by IC100. These findings indicate that stroke initiates a catecholamine surge that induces inflammasome activation and pyroptosis in the heart that is blocked by IC100, thus providing a framework for the development of therapeutics for stroke-related cardiovascular injury.

Intracranial atherosclerotic disease (ICAD) is a major cause of stroke globally, with mechanisms presumed to be shared with atherosclerosis in other vascular regions. Due to the scarcity of relevant animal models, testing biological hypotheses specific to ICAD is challenging. We developed a workflow to create patient-specific models of the middle cerebral artery (MCA) from neuroimaging studies, such as CT angiography. These models, which can be endothelialized with human endothelial cells and subjected to flow forces, provide a reproducible ICAD model. Using imaging from the SAMMPRIS clinical trial, we validated this novel model. Computational fluid dynamics flow velocities correlated strongly with particle-derived flow, regardless of stenosis degree. Post-stenotic flow disruption varied with stenosis severity. Single-cell RNA-seq identified flow-dependent endothelial gene expression and specific endothelial subclusters in diseased MCA segments, including upregulated genes linked to atherosclerosis. Confocal microscopy revealed flow-dependent changes in endothelial cell proliferation and morphology in vessel segments related to stenosis. This platform, rooted in the specific anatomy of cerebral circulation, enables detailed modeling of ICAD lesions and pathways. Given the high stroke risk associated with ICAD and the lack of effective treatments, these experimental models are crucial for developing new ICAD-related stroke therapies.

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of amyloid-beta peptides within cerebral blood vessels, leading to neurovascular complications. Ischemic strokes result from acute disruptions in cerebral blood flow, triggering metabolic disturbances and neurodegeneration. Both conditions often co-occur and are associated with respiratory dysfunctions. The retrotrapezoid nucleus (RTN), which is crucial for CO₂ sensing and breathing regulation in the brainstem, may play a key role in breathing disorders seen in these conditions. This study aims to investigate the role of Transforming Growth Factor Beta (TGF-β) signaling in the RTN on respiratory and cognitive functions in CAA, both with and without concurrent ischemic stroke. Adult male Tg-SwDI (CAA model) mice and C57BL/6 wild-type controls underwent stereotaxic injections of lentivirus targeting TGF-βR2 in the RTN. Stroke was induced by middle cerebral artery occlusion using a monofilament. Respiratory functions were assessed using whole-body plethysmography, while cognitive functions were evaluated through the Barnes Maze and Novel Object Recognition Test (NORT). Immunohistochemical analysis was conducted to measure TGF-βR2 and GFAP expressions in the RTN. CAA mice exhibited significant respiratory dysfunctions, including reduced respiratory rates and increased apnea frequency, as well as impaired cognitive performance. TGF-βR2 silencing in the RTN improved respiratory functions and cognitive outcomes in CAA mice. In CAA mice with concurrent stroke, TGF-βR2 silencing similarly enhanced respiratory and cognitive functions. Immunohistochemistry confirmed reduced TGF-βR2 and GFAP expressions in the RTN following silencing. Our findings demonstrate that increased TGF-β signaling and gliosis in the RTN contribute to respiratory and cognitive dysfunctions in CAA and CAA with stroke. Targeting TGF-βR2 signaling in the RTN offers a promising therapeutic strategy to mitigate these impairments. This study is the first to report a causal link between brainstem gliosis and both respiratory and cognitive dysfunctions in CAA and stroke models.

Intracranial artery stenosis (ICAS) is a significant contributor to ischemic stroke, with the RNF213 p.Arg4810Lys variant identified as a related genetic factor. We explored the clinical outcomes of the RNF213 genotype in patients with asymptomatic ICAS. Between November 2011 and March 2019, 139 patients with asymptomatic ICAS were enrolled in this study. Genotyping for RNF213 p.Arg4810Lys was performed using Sanger sequencing. A comprehensive analysis was conducted to compare the RNF213 genotype with background characteristics and clinical outcomes such as ipsilateral ischemic cerebrovascular events and stenosis progression. RNF213 p.Arg4810Lys was found in 25% of cases, revealing distinct clinical features between carriers and non-carriers. The incidence of ipsilateral ischemic cerebrovascular events was 4.3% (6/139 cases), and stenosis progression was observed in 13% (18/139 cases) during a mean follow-up period of 58 months. Stenosis progression rates were notably higher in the RNF213 variant group (25.7%; 9/35 cases) than in the RNF213 wild-type group (8.7%; 9/104 cases). Cumulative stenosis progression rate was significantly higher in the RNF213 variant group than in the RNF213 wild-type group (log-rank test, P = 0.0004). Multivariate Cox regression analysis indicated a significant association between the RNF213 p.Arg4810Lys variant and an increased risk of stenosis progression (P = 0.03, odds ratio 3.2; 95% confidence interval, 1.1-9.0). The RNF213 p.Arg4810Lys variant exhibits clinical disparities in asymptomatic ICAS and is notably linked to a heightened risk of stenosis progression. These results suggest a distinct difference in the vascular stenosis mechanism associated with this variant, warranting further investigation into its clinical implications and potential mechanistic insights.

Platelet aggregation is intimately associated with vascular inflammation and is commonly seen on routine histology studies of cerebral aneurysms. Platelets, when activated, have been shown to augment neutrophil response and the pro-inflammatory cascade. Platelet-neutrophil complexes have been found to aggravate atherosclerosis through a positive feedback loop. We hypothesized that targeting platelet aggregation and downstream inflammation could be used to prevent aneurysm formation and progression. First, we induced cerebral aneurysm formation in a previously described intracranial aneurysm model via carotid artery ligation, hypertension, and stereotactic elastase injection in C57BL/6 mice and analyzed vessels for lesion and thrombus formation. Raybiotech cytokine arrays were used to analyze 96 cytokines in induced murine aneurysms and 120 cytokines in human tissue samples. Cerebral aneurysm formation and inflammatory pathway were then studied in animals treated with IgG2 antibody (control), anti-GpIb antibody (platelet depletion), 1:10 DMSO:PBS (control), clopidogrel, anti-CXCR1/2 small molecule inhibitor, or anti-CXCL7 antibody. Bleeding assays and flow cytometry were used to evaluate platelet function in treated groups. CD31 + platelet aggregates are a common feature in human and mouse cerebral aneurysm specimens. Platelet ablation in mice prevents cerebral aneurysm formation (20% vs 100% in control antibody-treated mice, n = 5 each, p = 0.0476). Mice treated with 1 mg/kg clopidogrel develop significantly less aneurysms than controls (18% vs 73%, n = 11 and 11, respectively, p = 0.03). Semi-quantitative analysis of 96 different cytokines using Raybiotech arrays shows increased protein expression of CXCL7 in murine cerebral aneurysms when compared to controls. Treatment with clopidogrel results in reciprocal decrease in detected CXCL7. Targeting CXCL7-CXCR1/2 axis with 10 mg/kg reparixin (CXCR1/2 antagonist) significantly decreases cerebral aneurysm formation (11% vs 73%, n = 9 and 11, p = 0.0098) while treatment with 10 mg/kg SB225002 tends to decrease aneurysm formation (36% vs 73%, n = 11 vs n = 7, p = 0.11). Lastly, specific antibody blockade against CXCL7 using anti-CXCL7 antibody at 100 ug/mL significantly decreases cerebral aneurysm formation (29% vs 75%, n = 7 vs n = 8, p = 0.046). Platelet inflammation has an important role in cerebral aneurysm formation. Small molecule inhibitors targeting platelet CXCL7-CXCR1/2 inflammatory axis could be used to prevent cerebral aneurysm formation or progression.

Overweight/obese patients experience a lower incidence of subarachnoid hemorrhage (SAH) compared to non-overweight patients, even though elevated body mass index (BMI) has been associated with various SAH risk factors. Given that intracranial aneurysms are a primary cause of SAH, a potential protective effect of a high BMI on intracranial aneurysms is likely but remains insufficiently investigated. This population-based MRI study aims to conduct detailed analyses on risk factors associated with the incidence of unruptured intracranial aneurysms (UIA). Retrospective analysis of subjects enrolled in the prospective Hamburg City Health study who underwent intracranial magnetic resonance imaging (MRI) was done. MRI scans were screened for UIA using time-of-flight angiography. Subject data including medical history, laboratory examinations, and risk factors for UIA were collected, and a multivariable logistic regression model was used to investigate the relationship between risk factors and UIA incidence. 2688 subjects (mean (IQR) age, 65 (58-71); 1176 female (43.8%) were included. An UIA was detected in 214 subjects with an incidence of 10.6% (6.0%) in females (males). Determinants for UIA were female sex (OR 2.00, 95%CI 1.45-2.77, p < 0.001), hypertension (OR 1.48, 95%CI 1.08-2.04, p = 0.015), smoking (OR 1.41, 95%CI 1.03-1.95, p = 0.036), and BMI (OR 0.95, 95%CI 0.91-0.98, p = 0.004). Among subjects with UIA, 9.4% with a BMI > 25 had multiple aneurysms, compared to 21.6% with BMI ≤ 25 (p = 0.012). This study suggests that a high BMI exhibits a protective effect on UIA incidence and the development of multiple aneurysms. Additionally, the data confirms established risk factors for UIA development, such as female sex, hypertension, and smoking.

Previous studies have suggested that enlarged perivascular spaces (EPVSs) are potential radiological markers of cerebral ischemia in moyamoya disease (MMD). However, serial changes in EPVSs after surgical revascularization have not yet been clarified. We aimed to elucidate the postoperative changes in EPVSs in adult patients with MMD, clinical and radiological factors affecting the number of EPVSs, and the degree of postoperative changes. We counted the EPVSs in the centrum semiovale in each hemisphere on a T2-weighted MRI performed before surgery. EPVSs were quantified 3 months and 2 years after combined bypass surgery in surgically treated patients and compared with the number of EPVSs before surgery. We performed multivariate logistic regression analysis to identify the clinical and radiological factors associated with the number of EPVSs. This study included 120 hemispheres of 65 adults with MMD. Older age (P < 0.01), posterior cerebral artery (PCA) involvement (P < 0.01), and cerebral blood flow (CBF) impairment (P = 0.02) were significantly associated with a large number of EPVSs. The number of EPVSs markedly decreased at 3 months and 2 years after surgery compared with that before surgery (P < 0.01). PCA involvement (P = 0.04) and CBF impairment (P = 0.02) were independent predictors of the regression of EPVSs after surgery. The number of EPVSs in the centrum semiovale was closely associated with age, PCA involvement, and CBF impairment in adult patients with MMD, which remarkably regressed after surgical revascularization, especially in the hemispheres with PCA involvement and CBF impairment. EPVSs are reversible radiological markers reflecting impaired cerebral hemodynamics in adult patients with MMD.

Evidence indicates that the complement system is activated and plays a role in brain injury after intracerebral hemorrhage (ICH). Most studies have focused on the role of C3, C5 and the membrane attack complex. The purpose of this study was to investigate the potential impact of complement C1q, a key upstream component of the classical pathway, on ICH-induced brain injury. Wild-type (WT) and C1qa knock out (KO) mice were compared using an autologous blood injection ICH model. Magnetic resonance imaging (MRI) was performed on days 1, 3 and 7 and brains harvested on days 3 and 7 for immunohistochemistry to examine brain injury mechanisms. WT and C1qa KO mice also received an intracerebral injection of thrombin, a key factor in ICH-induced brain injury. Following MRI scans, brains were harvested for immunohistochemistry on day 1. In comparison to WT mice, C1qa KO mice had reduced hematoma erythrolysis and neutrophil infiltration after ICH. However, they also had delayed hematoma clearance, which was associated with reduced induction of phagocytic multinuclear giant cells, and increased perihematomal neuronal damage. After thrombin injection, C1qa KO mice had smaller lesion volumes, less neuronal loss, reduced neutrophil infiltration, and less BBB damage. C1qa knockout has beneficial and detrimental effects on ICH-induced brain injury mechanisms, but a consistent beneficial effect after thrombin injection. Strategies to balance the roles of C1q after ICH may represent a promising therapeutic direction.

Moyamoya disease (MMD) is a chronic cerebrovascular disorder that can lead to stroke and neurological dysfunctions. Given the largely sporadic nature and the role of gene-environment interactions in various diseases, we examined epigenetic modifications in MMD. We performed genome-wide DNA methylation using Illumina 850 K Methylation EPIC BeadChip, in two racially distinct adult female cohorts: a non-Asian cohort (13 MMD patients and 7 healthy controls) and an Asian cohort (14 MMD patients and 3 healthy controls). An additional external cohort with both sexes (females: 5 MMD patients and 5 healthy controls, males: 5 MMD patients and 5 healthy controls) was included for validation. Our findings revealed strikingly low DNA methylation variability between MMD patients and healthy controls, in both MMD female cohorts. In the non-Asian cohort, only 6 probes showed increased variability versus 647 probes that showed decreased variability. Similarly, in the Asian cohort, the MMD group also displayed a reduced methylation variability across all 2845 probes. Subsequent analysis showed that these differentially variable probes are located on genes involved in key biological processes such as methylation and transcription, DNA repair, cytoskeletal remodeling, natural killer cell signaling, cellular growth, and migration. These findings mark the first observation of low methylation variability in any disease, contrasting with the high variability observed in other disorders. This reduced methylation variability in MMD may hinder patients' adaptability to environmental shifts, such as hemodynamic stress, thereby influencing vascular homeostasis and contributing to MMD pathology. These findings offer new insights into the mechanisms of MMD and potential treatment strategies.