Project description:AimsSirt3 is one member of the NAD+ -dependent protein deacetylase family and plays crucial roles in diverse aspects of mammalian biological function. Then the role of Sirt3 on ischemia stroke is unknown.MethodsTo examine the effect of Sirt3 on ischemic stroke, we performed transient middle cerebral artery occlusion (tMCAO) in adult male Sirt3 knockout (KO) and wild-type (WT) mice.ResultsThe level of Sirt3 in infarct region is decreased after ischemic stroke. In addition, we found that Sirt3 KO mice showed worse neurobehavioral outcome compared with WT mice, accompanied by decreased neurogenesis and angiogenesis as shown by the reduction in number of DCX+ /BrdU+ cells, NeuN+ /BrdU+ cells, and CD31+ /BrdU+ cells in the perifocal region during recovery phase after ischemic stroke. Furthermore, Sirt3 deficiency reduced the activation of vascular endothelial growth factor (VEGF), AKT, and extracellular signal-regulated kinases (ERK) signaling pathways.ConclusionOur results indicated that Sirt3 is beneficial to neurovascular and functional recovery following chronic ischemic stroke.
Project description:Although the innate immune response to induce postischemic inflammation is considered as an essential step in the progression of cerebral ischemia injury, the role of innate immunity mediator NLRP3 in the pathogenesis of ischemic stroke is unknown. In this study, focal ischemia was induced by middle cerebral artery occlusion in NLRP3(-/-), NOX2(-/-), or wild-type (WT) mice. By magnetic resonance imaging (MRI), Evans blue permeability, and electron microscopic analyses, we found that NLRP3 deficiency ameliorated cerebral injury in mice after ischemic stroke by reducing infarcts and blood-brain barrier (BBB) damage. We further showed that the contribution of NLRP3 to neurovascular damage was associated with an autocrine/paracrine pattern of NLRP3-mediated interleukin-1? (IL-1?) release as evidenced by increased brain microvessel endothelial cell permeability and microglia-mediated neurotoxicity. Finally, we found that NOX2 deficiency improved outcomes after ischemic stroke by mediating NLRP3 signaling. This study for the first time shows the contribution of NLRP3 to neurovascular damage and provides direct evidence that NLRP3 as an important target molecule links NOX2-mediated oxidative stress to neurovascular damage in ischemic stroke. Pharmacological targeting of NLRP3-mediated inflammatory response at multiple levels may help design a new approach to develop therapeutic strategies for prevention of deterioration of cerebral function and for the treatment of stroke.
Project description:The consequences of cerebrovascular disease are among the leading health issues worldwide. Large and small cerebral vessel disease can trigger stroke and contribute to the vascular component of other forms of neurological dysfunction and degeneration. Both forms of vascular disease are driven by diverse risk factors, with hypertension as the leading contributor. Despite the importance of neurovascular disease and subsequent injury after ischemic events, fundamental knowledge in these areas lag behind our current understanding of neuroprotection and vascular biology in general. The goal of this review is to address select key structural and functional changes in the vasculature that promote hypoperfusion and ischemia, while also affecting the extent of injury and effectiveness of therapy. In addition, as damage to the blood-brain barrier is one of the major consequences of ischemia, we discuss cellular and molecular mechanisms underlying ischemia-induced changes in blood-brain barrier integrity and function, including alterations in endothelial cells and the contribution of pericytes, immune cells, and matrix metalloproteinases. Identification of cell types, pathways, and molecules that control vascular changes before and after ischemia may result in novel approaches to slow the progression of cerebrovascular disease and lessen both the frequency and impact of ischemic events.
Project description:Genetic changes due to dietary intervention in the form of either calorie restriction (CR) or intermittent fasting (IF) are not reported in detail until now. However, it is well established that both CR and IF extend the lifespan and protect against neurodegenerative diseases and stroke. The current research aims were first to describe the transcriptomic changes in brains of IF mice and, second, to determine whether IF induces extensive transcriptomic changes following ischemic stroke to protect the brain from injury. Mice were randomly assigned to ad libitum feeding (AL), 12 (IF12) or 16 (IF16) h daily fasting. Each diet group was then subjected to sham surgery or middle cerebral artery occlusion and consecutive reperfusion. Mid-coronal sections of ipsilateral cerebral tissue were harvested at the end of the 1 h ischemic period or at 3, 12, 24 or 72 h of reperfusion, and genome-wide mRNA expression was quantified by RNA sequencing. The cerebral transcriptome of mice in AL group exhibited robust, sustained up-regulation of detrimental genetic pathways under ischemic stroke, but activation of these pathways was suppressed in IF16 group. Interestingly, the cerebral transcriptome of AL mice was largely unchanged during the 1 h of ischemia, whereas mice in IF16 group exhibited extensive up-regulation of genetic pathways involved in neuroplasticity and down-regulation of protein synthesis. Our data provide a genetic molecular framework for understanding how IF protects brain cells against damage caused by ischemic stroke, and reveal cellular signaling and bioenergetic pathways to target in the development of clinical interventions.
Project description:Ischemic stroke, which accounts for 87% of all strokes, constitutes the leading cause of morbidity and mortality in China. Although the genetics and epigenetics of stroke have been extensively investigated, few studies have examined their relationships at different stages of stroke. This study assessed the characteristics of transcriptome changes at different stages of ischemic stroke using a mouse model of transient middle cerebral artery occlusion (tMCAO) and bioinformatics analyses. Cerebral cortex tissues from tMCAO mice at days 1, 3, 7, 14, and 28 were removed for RNA-Seq and small RNA-Seq library construction, sequencing, and bioinformatics analysis. We identified differentially expressed (DE) genes and miRNAs and revealed an association of the up-regulated or down-regulated DEmiRNAs with the correspondingly altered DEgene targets at each time point. In addition, different biological pathways were activated at different time points; thus, three groups of miRNAs were verified that may represent potential clinical biomarkers corresponding to days 1, 3, and 7 after ischemic stroke. Notably, this represents the first functional association of some of these miRNAs with stroke, e.g., miR-2137, miR-874-5p, and miR-5099. Together, our findings lay the foundation for the transition from a single-point, single-drug stroke treatment approach to multiple-time-point multi-drug combination therapies.
Project description:BackgroundIschemic stroke is a disease with high rate of death and disability worldwide. CircRNAs, as a novel type of non-coding RNAs, lacking 5' caps and 3' poly-A tails, has been associated with ischemic stroke. This study aimed to investigate key circRNAs related to ischemic stroke.MethodsRNA sequencing was performed obtain the circRNA expression profiles from peripheral whole blood of three ischemic stroke patients and three healthy individuals. Through bioinformatic analysis, differentially expressed circRNAs (DEcircRNAs) were identified, and GO and pathway analyses for the host genes of DEcircRNAs were conducted. The expression levels of selected circRNAs were analyzed with qRT-PCR. To further explore the functions of key circRNAs, a DEcircRNA-miRNA interaction network was constructed.ResultsA total of 736 DEcircRNAs were detected in ischemic stroke. Functional annotation of host genes of DEcircRNAs revealed several significantly enriched pathways, including Fc epsilon RI signaling pathway, B cell receptor signaling pathway, and T cell receptor signaling pathway. The qRT-PCR results were largely in keeping with our RNA-seq data. The ROC curve analyses indicated that hsa_circ_0000745, hsa_circ_0001459, hsa_circ_0003694 and hsa_circ_0007706 with relatively high diagnostic value. A circRNA-miRNA network, including 1544 circRNA-miRNA pairs, 456 circRNAs and 4 miRNAs, was obtained.ConclusionsThe results of our study may help to elucidate the specific mechanism underlying ischemic stroke.
Project description:Background: Innate immune response to neuronal death is one of the key events of the pathogenesis of ischemic brain injury. Interleukin-1 receptor-associated kinase (IRAK)-M, encoded by gene Irak3, negatively regulates toll-like receptor signaling by interacting with the MyD88-IRAK-4-IRAK-1 complex and blocking the phosphorylation and dissociation of IRAK-1. Its function in the ischemic stroke is unknown. Objective: This study aims to investigate whether IRAK-M deficiency could exacerbate neuroinflammation and neurovascular injuries during cerebral ischemia and reperfusion. Methods: Male C57BL/6 mice and Irak3 knockout mice were subjected to 45 min of middle cerebral artery occlusion and 4 or 24 h of reperfusion. Transcription of Irak3 gene was evaluated by quantitative real-time PCR (qRT-PCR). Then, infarct volume, neurological score, brain water content, and Evans blue leakage were compared between knock-out and wild-type mice after reperfusion. Through the observation of gross brain specimen after cerebral ischemia, the incidence of hemorrhage transformation was compared between KO and WT mice. To explore underlying signaling pathways involved in IRAK-M deficiency, major proinflammatory cytokines and NF-?B signaling were measured by qRT-PCR and Western blot. Results: The expression of IRAK-M peaked at 1 h after reperfusion, and then gradually decreased within the first 24 h, which was abolished by blocking the expression of hypoxia induced factor 1?. IRAK-M deficiency increased infarct volume, brain edema, the incidence of hemorrhage transformation, and the permeability of blood-brain barrier. In addition, the NF-?B-mediated expressions of proinflammatory cytokines and the activation of microglia in the ipsilateral brain from knock-out mice were much higher than those in wild-type littermates. Conclusion: IRAK-M deletion exacerbates neurovascular damages which are related to the pronounced activation of NF-?B signaling and neuroinflammatory responses during cerebral ischemia-reperfusion in mice. Our study indicates that IRAK-M has neuroprotective effect and has potential to facilitate the development of new pharmaceuticals that reduce neurovascular complications.
Project description:BACKGROUND:In ischemic stroke, the function of the cerebral vasculature is impaired. This vascular structure is formed by the so-called neurovascular unit (NVU). A better understanding of the mechanisms involved in NVU dysfunction and recovery may lead to new insights for the development of highly sought therapeutic approaches. To date, there remains an unmet need for complex human in vitro models of the NVU to study ischemic events seen in the human brain. METHODS:We here describe the development of a human NVU on-a-chip model using a platform that allows culture of 40 chips in parallel. The model comprises a perfused vessel of primary human brain endothelial cells in co-culture with induced pluripotent stem cell derived astrocytes and neurons. Ischemic stroke was mimicked using a threefold approach that combines chemical hypoxia, hypoglycemia, and halted perfusion. RESULTS:Immunofluorescent staining confirmed expression of endothelial adherens and tight junction proteins, as well as astrocytic and neuronal markers. In addition, the model expresses relevant brain endothelial transporters and shows spontaneous neuronal firing. The NVU on-a-chip model demonstrates tight barrier function, evidenced by retention of small molecule sodium fluorescein in its lumen. Exposure to the toxic compound staurosporine disrupted the endothelial barrier, causing reduced transepithelial electrical resistance and increased permeability to sodium fluorescein. Under stroke mimicking conditions, brain endothelial cells showed strongly reduced barrier function (35-fold higher apparent permeability) and 7.3-fold decreased mitochondrial potential. Furthermore, levels of adenosine triphosphate were significantly reduced on both the blood- and the brain side of the model (4.8-fold and 11.7-fold reduction, respectively). CONCLUSIONS:The NVU on-a-chip model presented here can be used for fundamental studies of NVU function in stroke and other neurological diseases and for investigation of potential restorative therapies to fight neurological disorders. Due to the platform's relatively high throughput and compatibility with automation, the model holds potential for drug compound screening.