Project description:The risk of ischemic stroke increases substantially with age, making it the third leading cause of death and the leading cause of long-term disability in the world. Numerous studies demonstrated that genes, RNAs, and proteins are involved in the occurrence and development of stroke. Current studies found that microRNAs (miRNAs or miRs) are also closely related to the pathological process of stroke. miRNAs are a group of short, noncoding RNA molecules playing important role in posttranscriptional regulation of gene expression and they have emerged as regulators of ischemic preconditioning and ischemic postconditioning. Here we give an overview of the expression and function of miRNAs in the brain, miRNAs as biomarkers during cerebral ischemia, and clinical applications and limitations of miRNAs. Future prospects of miRNAs are also discussed.
Project description:Cerebral ischemia is caused by perturbations in blood flow to the brain that trigger sequential and complex metabolic and cellular pathologies. This leads to brain tissue damage, including neuronal cell death and cerebral infarction, manifesting clinically as ischemic stroke, which is the cause of considerable morbidity and mortality worldwide. To analyze the underlying biological mechanisms and identify potential biomarkers of ischemic stroke, various in vitro and in vivo experimental models have been established investigating different molecular aspects, such as genes, microRNAs, and proteins. Yet, the metabolic and cellular pathologies of ischemic brain injury remain not fully elucidated, and the relationships among various pathological mechanisms are difficult to establish due to the heterogeneity and complexity of the disease. Metabolome-based techniques can provide clues about the cellular pathologic status of a condition as metabolic disturbances can represent an endpoint in biological phenomena. A number of investigations have analyzed metabolic changes in samples from cerebral ischemia patients and from various in vivo and in vitro models. We previously analyzed levels of amino acids and organic acids, as well as polyamine distribution in an in vivo rat model, and identified relationships between metabolic changes and cellular functions through bioinformatics tools. This review focuses on the metabolic and cellular changes in cerebral ischemia that offer a deeper understanding of the pathology underlying ischemic strokes and contribute to the development of new diagnostic and therapeutic approaches.
Project description:Treatment efficacy for ischemic stroke represents a major challenge. Despite fundamental advances in the understanding of stroke etiology, therapeutic options to improve functional recovery remain limited. However, growing knowledge in the field of epigenetics has dramatically changed our understanding of gene regulation in the last few decades. According to the knowledge gained from animal models, the manipulation of epigenetic players emerges as a highly promising possibility to target diverse neurologic pathologies, including ischemia. By altering transcriptional regulation, epigenetic modifiers can exert influence on all known pathways involved in the complex course of ischemic disease development. Beneficial transcriptional effects range from attenuation of cell death, suppression of inflammatory processes, and enhanced blood flow, to the stimulation of repair mechanisms and increased plasticity. Most striking are the results obtained from pharmacological inhibition of histone deacetylation in animal models of stroke. Multiple studies suggest high remedial qualities even upon late administration of histone deacetylase inhibitors (HDACi). In this review, the role of epigenetic mechanisms, including histone modifications as well as DNA methylation, is discussed in the context of known ischemic pathways of damage, protection, and regeneration.
Project description:Stroke is a highly prevalent and devastating disease with limited therapeutic options. Most efforts to develop treatments for stroke have thus far met with limited success in large clinical trials. The brain has an enormous capacity for self-preservation, and elucidating how the brain protects itself may provide novel insights into stroke treatment. Ischemic tolerance (IT), a phenomenon in which application of sub-lethal stress [preconditioning (PC) stimulus; PC] induces a state of tolerance to a subsequent ischemic insult, represents an example of endogenous neuroprotection. IT can be induced in brain by systemic administration of the Toll-like receptor-4 ligand lipopolysaccharide (LPS). Different populations of immune cell could potentially play a role in PC induced by LPS. In particular, monocytes, which are the main target of LPS, can exert a powerful protective effect either directly or by modulating the immune system.
Project description:In ischemic stroke, DWI-T2 mismatch (positive signals on DWI but negative signals on T2) indicates ischemia within 4.5 h. However, the molecular expression pattern of this region remains elusive. This project aimed to reveal the proteomics profiling of the brain tissues at DWI-T2 mismatch, T2(+), and contralateral regions of brain within 4.5 h after middle cerebral artery occlusion compared with naïve brains of mice.
Project description:Global brain ischemia/reperfusion induces neuronal damage in vulnerable brain regions, leading to mitochondrial dysfunction and subsequent neuronal death. Induction of neuronal death is mediated by release of cytochrome c (cyt c) from the mitochondria though a well-characterized increase in outer mitochondrial membrane permeability. However, for cyt c to be released it is first necessary for cyt c to be liberated from the cristae junctions which are gated by Opa1 oligomers. Opa1 has two known functions: maintenance of the cristae junction and mitochondrial fusion. These roles suggest that Opa1 could play a central role in both controlling cyt c release and mitochondrial fusion/fission processes during ischemia/reperfusion. To investigate this concept, we first utilized in vitro real-time imaging to visualize dynamic changes in mitochondria. Oxygen-glucose deprivation (OGD) of neurons grown in culture induced a dual-phase mitochondrial fragmentation profile: (i) fragmentation during OGD with no apoptosis activation, followed by fusion of mitochondrial networks after reoxygenation and a (ii) subsequent extensive fragmentation and apoptosis activation that preceded cell death. We next evaluated changes in mitochondrial dynamic state during reperfusion in a rat model of global brain ischemia. Evaluation of mitochondrial morphology with confocal and electron microscopy revealed a similar induction of fragmentation following global brain ischemia. Mitochondrial fragmentation aligned temporally with specific apoptotic events, including cyt c release, caspase 3/7 activation, and interestingly, release of the fusion protein Opa1. Moreover, we uncovered evidence of loss of Opa1 complexes during the progression of reperfusion, and electron microscopy micrographs revealed a loss of cristae architecture following global brain ischemia. These data provide novel evidence implicating a temporal connection between Opa1 alterations and dysfunctional mitochondrial dynamics following global brain ischemia.
Project description:The imaging workup for patients with suspected acute ischemic stroke has advanced significantly over the past few years. Evaluation is no longer limited to noncontrast computed tomography, but now frequently also includes vascular and perfusion imaging. Although acute stroke imaging has made significant progress in the last few decades with the development of multimodal approaches, there are still many unanswered questions regarding their appropriate use in the setting of daily patient care. It is important for all physicians taking care of stroke patients to be familiar with current multimodal computed tomography and magnetic resonance imaging techniques, including their strengths, limitations, and their role in guiding therapy.
Project description:The sulfonylurea receptor 1 (Sur1)-transient receptor potential 4 (Trpm4) channel is an important molecular element in focal cerebral ischemia. The channel is upregulated in all cells of the neurovascular unit following ischemia, and is linked to microvascular dysfunction that manifests as edema formation and secondary hemorrhage, which cause brain swelling. Activation of the channel is a major molecular mechanism of cytotoxic edema and "accidental necrotic cell death." Blockade of Sur1 using glibenclamide has been studied in different types of rat models of stroke: (i) in conventional non-lethal models (thromboembolic, 1-2 h temporary, or permanent middle cerebral artery occlusion), glibenclamide reduces brain swelling and infarct volume and improves neurological function; (ii) in lethal models of malignant cerebral edema, glibenclamide reduces edema, brain swelling, and mortality; (iii) in models with rtPA, glibenclamide reduces swelling, hemorrhagic transformation, and death. Retrospective studies of diabetic patients who present with stroke have shown that those whose diabetes is managed with a sulfonylurea drug and who are maintained on the sulfonylurea drug during hospitalization for stroke have better outcomes at discharge and are less likely to suffer hemorrhagic transformation. Here, we provide a comprehensive review of the basic science, preclinical experiments, and retrospective clinical studies on glibenclamide in focal cerebral ischemia and stroke. We also compare the preclinical work in stroke models to the updated recommendations of the Stroke Therapy Academic Industry Roundtable (STAIR). The findings reviewed here provide a strong foundation for a translational research program to study glibenclamide in patients with ischemic stroke.
Project description:Autophagy has evolved as a conserved process for the bulk degradation and recycling of cytosolic components, such as long-lived proteins and organelles. In neurons, autophagy is important for homeostasis and protein quality control and is maintained at relatively low levels under normal conditions, while it is upregulated in response to pathophysiological conditions, such as cerebral ischemic injury. However, the role of autophagy is more complex. It depends on age or brain maturity, region, severity of insult, and the stage of ischemia. Whether autophagy plays a beneficial or a detrimental role in cerebral ischemia depends on various pathological conditions. In this review, we elucidate the role of neuronal autophagy in cerebral ischemia.
Project description:Background and Purpose: Long noncoding RNAs (lncRNAs) are an emerging class of genomic regulatory molecules reported in neurodevelopment and many diseases. Despite extensive studies have identified lncRNAs and discovered their functions in CNS diseases, the function of lncRNAs in ischemia stroke remains poorly understood. Method: Ischemia was induced by transient middle cerebral artery occlusion. Expression profiles of lncRNAs, miRNAs and mRNAs after ischemia stroke were obtained using high throughput sequencing technology. A correlation network was constructed to predict lncRNA functions. LncRNA-miRNA-mRNA network was constructed to discover ceRNAs. Results: 1924 novel lncRNAs were identified, indicating that the ischemia stroke has a complex effect on lncRNAs. The top 10 regulated lncRNAs was validated by qRT-PCR. We have also predicted function of lncRNAs, and subjected them to gene co-expression network analysis, revealing the involvement of lncRNAs in many important biological process including injury and repair that are implicated in the regulation of ischemia stroke. Furthermore, lncRNAs mediated SMD (Staufen1-mediated mRNA decay) was analyzed and ceRNA (competitive endogenous RNAs) network was constructed in ischemia stroke. Conclusions: This study reports the genome-wide lncRNA profiles in ischemia stroke using high throughput sequencing and constructs a systematic lncRNA-miRNA-mRNA network which reveals a complex functional noncoding RNA regulatory network in ischemia stroke.