ALDH2, a novel protector against stroke?
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ABSTRACT:
SUBMITTER: Sun A
PROVIDER: S-EPMC3698642 | biostudies-other | 2013 Jul
REPOSITORIES: biostudies-other
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Project description:Ischemic stroke (IS) is one of the leading causes of death and disability resulting in inevitable burden globally. Ischemic injury initiates cascade of pathological events comprising energy dwindling, failure of ionic gradients, failure of blood brain barrier (BBB), vasogenic edema, calcium over accumulation, excitotoxicity, increased oxidative stress, mitochondrial dysfunction, inflammation and eventually cell death. In spite of such complexity of the disease, the only treatment approved by US Food and Drug Administration (FDA) is tissue plasminogen activator (t-PA). This therapy overcome blood deficiency in the brain along with side effects of reperfusion which are responsible for considerable tissue injury. Therefore, there is urgent need of novel therapeutic perspectives that can protect the integrity of BBB and salvageable brain tissue. Advancement in nanomedicine is empowering new approaches that are potent to improve the understanding and treatment of the IS. Herein, we focus nanomaterial mediated drug delivery systems (DDSs) and their role to bypass and cross BBB especially via intranasal drug delivery. The various nanocarriers used in DDSs are also discussed. In a nut shell, the objective is to provide an overview of use of nanomedicine in the diagnosis and treatment of IS to facilitate the research from benchtop to bedside.
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Project description:To investigate the effects of peroxisome proliferator-activated receptor (PPAR)? in the cerebral vasculature following stroke-induced brain injury.Here, we report a novel finding that selective PPAR? genetic deletion in vascular smooth muscle cells (VSMCs) resulted in increased cerebrovascular permeability and brain infarction in mice after middle cerebral artery occlusion (MCAO). Mechanistically, we revealed for the first time that PPAR? expression is reduced, but matrix metalloproteinase (MMP)-9 activity is increased in cultured VSMCs after oxygen-glucose deprivation and also in the cerebral cortex of mice following MCAO. Moreover, gain- and loss of PPAR? function in VSMCs significantly reduces and increases oxygen-glucose deprivation-induced MMP-9 activity, respectively. We have further identified that MMP-9 is a direct target of PPAR?-mediated transrepression by chromatin immunoprecipitation and PPAR? transcriptional activity assays. Furthermore, inhibition of MMP-9 activity by lentiviral MMP-9 short hairpin RNA effectively improves cerebrovascular permeability and reduces brain infarction in VSMC-selective PPAR? conditional knockout mice after MCAO.Our data demonstrate that PPAR? in VSMCs can prevent ischemic brain injury by inhibition of MMP-9 activation and attenuation of postischemic inflammation. The pharmacological activation of PPAR? may provide a new therapeutic strategy to treat stroke-induced vascular and neuronal damage.
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Project description:Excessive and unresolved neuroinflammation is part of the pathological cascade in brain injuries such as acute ischemia, as well as neurodegenerative diseases, including multiple sclerosis and Alzheimer’s disease. Particularly, timely resolution of inflammation is critical for the recovery and repair after brain injury. The nuclear factor-κB (NF-κB) signaling plays a central role in neuroinflammation through transcriptional induction of proinflammatory genes. Here, we report that TRIM9, a brain-specific member of the TRIpartite motif (TRIM) family with ubiquitin E3 ligase activity, is upregulated in the peri-infarct cortical areas of mouse brain upon ischemic stroke, and governs the resolution of NF-κB-mediated neuroinflammation. Mechanistically, neuronal TRIM9 sequestered β-TrCP, a component of the Skp-Cullin-F-box (SCF) E3 ligase complex, from ubiquitinating IκBα, thereby mitigating NF-κB-dependent inflammatory responses including production of proinflammatory mediators and infiltration of immune cells. Consequently, Trim9 deficient mice were highly vulnerable to ischemia, manifesting uncontrolled neuroinflammation and exacerbated neuropathological and neurological outcomes. Systemic administration of recombinant adeno-associated virus (AAV)-PHP.B, allowing brain-wide enriched TRIM9 expression, effectively resolved neuroinflammation and alleviated neuronal death in aging mice. This reveals that TRIM9 is essential for fine tuning of NF-κB-dependent neuroinflammation, and TRIM9-potentiation based therapy may offer a new approach for the treatment of stroke and inflammation-related neurological disorders.
2018-12-31 | GSE114652 | GEO
Project description:Stroke is the most common type of cerebrovascular disease and is a leading cause of disability and death. Ischemic stroke accounts for approximately 80% of all strokes. The remaining 20% of strokes are hemorrhagic in nature. To date, therapeutic options for acute ischemic stroke are very limited. Recent research suggests that shifting microglial phenotype from the pro-inflammatory M1 state toward the anti-inflammatory and tissue-reparative M2 phenotype may be an effective therapeutic strategy for ischemic stroke. The dietary phytochemical curcumin has shown promise in experimental stroke models, but its effects on microglial polarization and long-term recovery after stroke are unknown. Here we address these gaps by subjecting mice to distal middle cerebral artery occlusion (dMCAO) and administering curcumin intraperitoneally (150 mg/kg) immediately after ischemia and 24 h later. Histological studies revealed that curcumin post-treatment significantly reduced cerebral ischemic damage 3 days after dMCAO. Sensorimotor functions-as measured by the adhesive removal test and modified Garcia scores-were superior in curcumin-treated mice at 3, 5, 7 and 10 days after stroke. RT-PCR measurements revealed an elevation of M2 microglia/macrophage phenotypic markers and a reduction in M1 markers in curcumin-treated brains 3 days after dMCAO. Immunofluorescent staining further showed that curcumin treatment significantly increased the number of CD206+Iba1+ M2 microglia/macrophages and reduced the number of CD16+Iba1+ M1 cells 10 days after stroke. In vitro studies using the BV2 microglial cell line confirmed that curcumin inhibited lipopolysaccharide (LPS) and interferon-γ (IFN-γ)-induced M1 polarization. Curcumin treatment concentration-dependently reduced the expression of pro-inflammatory cytokines, including TNF-α, IL-6 and IL-12p70, in the absence of any toxic effect on microglial cell survival. In conclusion, we demonstrate that curcumin has a profound regulatory effect on microglial responses, promoting M2 microglial polarization and inhibiting microglia-mediated pro-inflammatory responses. Curcumin post-treatment reduces ischemic stroke-induced brain damage and improves functional outcomes, providing new evidence that curcumin might be a promising therapeutic strategy for stroke.
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Project description:Microglia in hemorrhagic stroke contribute to both acute-phase exacerbation and late-phase attenuation of injury. Here, by using the mouse model, we reported that the shift in polarization of microglia from M1 to M2 phenotype could be altered by a past 'mini' stroke, resulting in better neurological function recovery, faster attenuation of lesion volume, and better survival. In mice with a previous stroke, M2 predominance appeared markedly in advance compared to mice without a previous stroke. Mechanistically, the RBC-mediated M2 polarization of microglia was synergistically enhanced by T cells: microglia cocultured with RBCs alone resulted in mild alterations to M2 markers, whereas in the presence of T cells, they expressed an early and sustained M2 response. These results suggest that by harnessing the microglia-mediated M2 polarization response, we could help mitigate devastating sequelae before a prospective hemorrhagic stroke even happens.
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Project description:Ischemic stroke is the leading cause of immortal disability and death worldwide. For treatment in the acute phase, it is necessary to control excessive reactive oxygen species (ROS) damage during ischemia/reperfusion (I/R). Microglia are well known to be closely associated with excessive ROS response in the early stage of I/R. However, the precise roles of microglia associated with mitigating ROS damage, and molecular markers of heterogenetic microglia in the I/R damaged brain has not been clarified. Here, we identified a new type of microglia associated with stroke in the I/R injured brain. Single-cell RNA sequencing (scRNA-seq) was used to assess transcriptional changes of microglia and immune cells in the contralateral (CL) and ipsilateral (IL) hemispheres after transient middle cerebral artery occlusion (tMCAO) surgery to mimic ischemic stroke. We classified a unique type of microglia with enhanced antioxidant function and markers similar to those of disease-associated microglia (DAM), designated them as stroke-associated microglia (SAM). The representative antioxidant enzyme, Peroxiredoxin-1 (Prdx1), was predominantly expressed in SAM and mediated ROS defense genes, including Txn1, Srx1, Mt1, and Mt2. In the Prdx1-/- I/R damaged brain, we observed significantly increased infarction, as assessed by TTC staining, and FACS analysis detected severe microglial cell death. Importantly, scRNA transcriptomics data showed that the SAM population was specifically decreased in Prdx1-/- mice and that these mice exhibited decreased ROS damage resistance. Inflammatory responses which were detected by ELISA and qPCR, were also increased in Prdx1-/- IL hemispheres. Finally, Prdx1-dependent antioxidative SAM were found to be essential for increasing the transcription levels of stroke-protective molecules, such as osteopontin and ferritin. A novel microglia type (SAM) is specifically activated in response to stroke I/R injury, and that Prdx1 expression is required for the activation and enhanced antioxidant function of SAM.
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Project description:Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that metabolizes ethanol and toxic aldehydes such as 4-hydroxy-2-nonenal (4-HNE). Using an unbiased proteomic search, we identified ALDH2 deficiency in stroke-prone spontaneously hypertensive rats (SHR-SP) as compared with spontaneously hypertensive rats (SHR). We concluded the causative role of ALDH2 deficiency in neuronal injury as overexpression or activation of ALDH2 conferred neuroprotection by clearing 4-HNE in in vitro studies. Further, ALDH2-knockdown rats revealed the absence of neuroprotective effects of PKCε. Moderate ethanol administration that is known to exert protection against stroke was shown to enhance the detoxification of 4-HNE, and to protect against ischemic cerebral injury through the PKCε-ALDH2 pathway. In SHR-SP, serum 4-HNE level was persistently elevated and correlated inversely with the lifespan. The role of 4-HNE in stroke in humans was also suggested by persistent elevation of its plasma levels for at least 6 months after stroke. Lastly, we observed that 21 of 1 242 subjects followed for 8 years who developed stroke had higher initial plasma 4-HNE levels than those who did not develop stroke. These findings suggest that activation of the ALDH2 pathway may serve as a useful index in the identification of stroke-prone subjects, and the ALDH2 pathway may be a potential target of therapeutic intervention in stroke.
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Project description:Following stroke, patients are commonly left with debilitating motor and speech impairments. This article reviews the state of the art in neurological repair for stroke and proposes a new model for the future. We suggest that stroke treatment--from the time of the ictus itself to living with the consequences--must be fundamentally neurological, from limiting the extent of injury at the outset, to repairing the consequent damage. Our model links brain and behaviour by targeting brain circuits, and we illustrate the model though action observation treatment, which aims to enhance brain network connectivity. The model is based on the assumptions that the mechanisms of neural repair inherently involve cellular and circuit plasticity, that brain plasticity is a synaptic phenomenon that is largely stimulus-dependent, and that brain repair required both physical and behavioural interventions that are tailored to reorganize specific brain circuits. We review current approaches to brain repair after stroke and present our new model, and discuss the biological foundations, rationales, and data to support our novel approach to upper-extremity and language rehabilitation. We believe that by enhancing plasticity at the level of brain network interactions, this neurological model for brain repair could ultimately lead to a cure for stroke.
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Project description:Stroke remains a leading cause of death and disability in the world. Over the past few decades our understanding of the pathophysiology of stroke has increased, but greater insight is required to advance the field of stroke recovery. Clinical treatments have improved in the acute time window, but long-term therapeutics remain limited. Complex neural circuits damaged by ischemia make restoration of function after stroke difficult. New therapeutic approaches, including cell transplantation or stimulation, focus on reestablishing these circuits through multiple mechanisms to improve circuit plasticity and remodeling. Other research targets intact networks to compensate for damaged regions. This review highlights several important mechanisms of stroke injury and describes emerging therapies aimed at improving clinical outcomes.
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