Destructive Effects of Pyroptosis on Homeostasis of Neuron Survival Associated with the Dysfunctional BBB-Glymphatic System and Amyloid-Beta Accumulation after Cerebral Ischemia/Reperfusion in Rats.
TL;DR: In this paper, the authors used lipopolysaccharide and glycine as the agonist and inhibitor of pyroptosis, respectively, for detecting the detection of pyproptosis and AQP-4, and Aβ1-42 oligomers.
Abstract: Neuroinflammation-related amyloid-beta peptide (Aβ) accumulation after cerebral ischemia/reperfusion (I/R) accounts for cerebral I/R injuries and poststroke dementia. Recently, pyroptosis, a proinflammatory cell death, has been identified as a crucial pathological link of cerebral I/R injuries. However, whether pyroptosis acts as a trigger of Aβ accumulation after cerebral I/R has not yet been demonstrated. Blood-brain barrier (BBB) and glymphatic system mediated by aquaporin-4 (AQP-4) on astrocytic endfeet are important pathways for the clearance of Aβ in the brain, and pyroptosis especially occurring in astrocytes after cerebral I/R potentially damages BBB integrity and glymphatic function and thus influences Aβ clearance and brain homeostasis. In present study, the method of middle cerebral artery occlusion/reperfusion (MCAO/R) was used for building models of focal cerebral I/R injuries in rats. Then, we used lipopolysaccharide and glycine as the agonist and inhibitor of pyroptosis, respectively, Western blotting for detections of pyroptosis, AQP-4, and Aβ1-42 oligomers, laser confocal microscopy for observations of pyroptosis and Aβ locations, and immunohistochemical stainings of SMI 71 (a specific marker for BBB integrity)/AQP-4 and Nissl staining for evaluating, respectively, BBB-glymphatic system and neuronal damage. The results showed that pyroptosis obviously promoted the loss of BBB integrity and AQP-4 polarization, brain edema, Aβ accumulation, and the formation of Aβ1-42 oligomers and thus increased neuronal damage after cerebral I/R. However, glycine could inhibit cerebral I/R-induced pyroptosis by alleviating cytomembrane damage and downregulating expression levels of cleaved caspase-11/1, N-terminal gasdermin D, NLRP3 (nucleotide-binding domain, leucine-rich repeat containing protein 3), interleukin-6 (IL-6) and IL-1β and markedly abate above pathological changes. Our study revealed that pyroptosis is a considerable factor causing toxic Aβ accumulation, dysfunctional BBB-glymphatic system, and neurological deficits after cerebral I/R, suggesting that targeting pyroptosis is a potential strategy for the prevention of ischemic stroke sequelae including dementia.
Citations
More filters
TL;DR: Quercetin, the active ingredient of the Xiaoyao Kangai Jieyu Formula, effectively mitigated the progression of BCRD by inhibiting pyroptosis, promoting immune response, and improving serum metabolism.
Abstract: Background Breast cancer-related depression (BCRD) seriously inhibits the life quality of patients with breast cancer. The Xiaoyao Kangai Jieyu Formula is known to inhibit the progression of depression. However, the detailed function of the Xiaoyao Kangai Jieyu Formula in BCRD remains unclear. Methods Network pharmacology was constructed to assess the downstream target of the Xiaoyao Kangai Jieyu Formula in BCRD. In addition, the tail suspension test, sucrose preference test, and forced swimming test were used to test the symptom of depression in mice. Fluoro-Jade B staining was performed to observe the structure of neurons. RT-qPCR and western blot were applied to evaluate mRNA and protein levels. Besides, ELISA was performed to test the inflammatory responses and the immune response-related cytokines. Results Quercetin was identified as the key component of the Xiaoyao Kangai Jieyu Formula. Quercetin significantly inhibited BCRD-induced neuron pyroptosis via downregulation of PYD and card domain containing (ASC), NLR family pyrin domain containing 3 (NLRP3), and caspase-1, and quercetin could reverse BCRD-caused inhibition of neuron viability. Quercetin significantly attenuated the symptom of BCRD in mice, and it could reverse the contents of 5-hydroxytryptamine (5-HT), dopamine (DA), and neutrophil elastase (NE) in mice. Moreover, quercetin could promote the immune responses in xenograft mice via upregulation of interleukin- (IL-) 2, interferon-γ (IFN-γ), and IL-10. Conclusion Quercetin, the active ingredient of the Xiaoyao Kangai Jieyu Formula, effectively mitigated the progression of BCRD by inhibiting pyroptosis, promoting immune response, and improving serum metabolism.
8 citations
TL;DR: The basic concepts of these drainage systems, including drainage routes, physiological functions, regulatory mechanisms, and detection technologies, are summarized and information for potential novel strategies for treatment of stroke is provided.
6 citations
TL;DR: In this paper, Tongxinluo (TXL) was used to prevent and treat post-stroke dementia in rats by downregulating expression levels of cleaved caspase-11/1, N-terminal gasdermin D, nucleotide binding oligomerization domain-like receptors pyrin domain containing 3 (NLRP3), interleukin-6 (IL-6), and cleaved IL-1β and abated astrocytic pyroptosis after cerebral I/R.
Abstract: Amyloid-β peptide (Aβ) accumulation is a detrimental factor in cerebral ischemia/reperfusion (I/R) injuries accounting for dementia induced by ischemic stroke. In addition to blood brain barrier (BBB), the glymphatic system mediated by aquaporin-4 (AQP-4) on astrocytic endfeet functions as an important pathway for the clearance of Aβ in the brain. Cerebral I/R induced astrocytic pyroptosis potentially causes the AQP-4 polarization loss and dysfunctional BBB-glymphatic system exacerbating the accumulation of Aβ. Furthermore, Aβ toxicity has been identified as a trigger of pyroptosis and BBB damage, suggesting an amplified effect of Aβ accumulation after cerebral I/R. Therefore, based on our previous work, this study was designed to explore the intervention effects of Tongxinluo (TXL) on astrocytic pyroptosis and Aβ accumulation after cerebral I/R in rats. The results showed that TXL intervention obviously alleviated the degree of pyroptosis by downregulating expression levels of cleaved caspase-11/1, N-terminal gasdermin D, nucleotide-binding oligomerization domain-like receptors pyrin domain containing 3 (NLRP3), interleukin-6 (IL-6), and cleaved IL-1β and abated astrocytic pyroptosis after cerebral I/R. Moreover, TXL intervention facilitated to restore AQP-4 polarization and accordingly relieve Aβ accumulation around astrocytes in ischemic cortex and hippocampus as well as the formation of toxic Aβ (Aβ1–42 oligomer). Our study indicated that TXL intervention could exert protective effects on ischemic brain tissues against pyroptotic cell death, inhibit astrocytic pyroptosis, and reduce toxic Aβ accumulation around astrocytes in cerebral I/R injuries. Furthermore, our study provides biological evidence for the potential possibility of preventing and treating poststroke dementia with TXL in clinical practice.
5 citations
TL;DR: It is found that overexpression of AQP4 in the mouse brain can effectively improve post-SAH neuronal ferroptosis and brain injury, at least partly by inhibiting transferrin infiltration into the brain parenchyma in the glymphatic system.
Abstract: The infiltration of blood components into the brain parenchyma through the lymphoid system is an important cause of subarachnoid hemorrhage injury. AQP4, a water channel protein located at the astrocyte foot, has been reported to regulate blood–brain barrier integrity, and its polarization is disrupted after SAH. Neuronal ferroptosis is involved in subarachnoid hemorrhage- (SAH-) induced brain injury, but the inducing factors are not completely clear. Transferrin is one of the inducing factors of ferroptosis. This study is aimed at researching the role and mechanism of AQP4 in brain injury after subarachnoid hemorrhage in mice. An experimental mouse SAH model was established by endovascular perforation. An AAV vector encoding AQP4 with a GFAP-specific promoter was administered to mice to achieve specific overexpression of AQP4 in astrocytes. PI staining, Fer-1 intervention, and transmission electron microscopy were used to detect neuronal ferroptosis, and dextran (40 kD) leakage was used to detect BBB integrity. Western blot analysis of perfused brain tissue protein samples was used to detect transferrin infiltration. First, neuronal ferroptosis 24 h after SAH was observed by PI staining and Fer-1 intervention. Second, a significant increase in transferrin infiltration was found in the brain parenchyma 24 h after SAH modeling, while transferrin content was positively correlated with neuronal ferroptosis. Then, we observed that AQP4 overexpression effectively improved AQP depolarization and BBB injury induced by SAH and significantly reduced transferrin infiltration and neuronal ferroptosis after SAH. Finally, we found that AQP4 overexpression could effectively improve the neurobehavioral ability of SAH mice, and the neurobehavioral ability was negatively correlated with transferrin brain content. Taken together, these data indicate that overexpression of AQP4 in the mouse brain can effectively improve post-SAH neuronal ferroptosis and brain injury, at least partly by inhibiting transferrin infiltration into the brain parenchyma in the glymphatic system.
5 citations
TL;DR: An "anchor" opinion is proposed, where Aβ42 aggregates in the ECM serve as the adverse "anchors" in the brain for anchoring neurons and for making neural cells inert, which causes their dysfunction.
3 citations
References
More filters
TL;DR: Seven of eight rats that underwent permanent occlusion of the MCA had resolving moderately severe neurologic deficits and unilateral infarcts averaging 37.6 +/- 5.5% of the coronal sectional area at 72 hours after the onset of Occlusion.
Abstract: To develop a simple, relatively noninvasive small-animal model of reversible regional cerebral ischemia, we tested various methods of inducing infarction in the territory of the right middle cerebral artery (MCA) by extracranial vascular occlusion in rats. In preliminary studies, 60 rats were anesthetized with ketamine and different combinations of vessels were occluded; blood pressure and arterial blood gases were monitored. Neurologic deficit, mortality rate, gross pathology, and in some instances, electroencephalogram and histochemical staining results were evaluated in all surviving rats. The principal procedure consisted of introducing a 4-0 nylon intraluminal suture into the cervical internal carotid artery (ICA) and advancing it intracranially to block blood flow into the MCA; collateral blood flow was reduced by interrupting all branches of the external carotid artery (ECA) and all extracranial branches of the ICA. In some groups of rats, bilateral vertebral or contralateral carotid artery occlusion was also performed. India ink perfusion studies in 20 rats documented blockage of MCA blood flow in 14 rats subjected to permanent occlusion and the restoration of blood flow to the MCA territory in six rats after withdrawal of the suture from the ICA. The best method of MCA occlusion was then selected for further confirmatory studies, including histologic examination, in five additional groups of rats anesthetized with halothane. Seven of eight rats that underwent permanent occlusion of the MCA had resolving moderately severe neurologic deficits (Grade 2 of 4) and unilateral infarcts averaging 37.6 +/- 5.5% of the coronal sectional area at 72 hours after the onset of occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)
6,428 citations
TL;DR: The NALP3 inflammasome is identified as a sensor of Aβ in a process involving the phagocytosis of A β and subsequent lysosomal damage and release of cathepsin B.
Abstract: The events leading to the inflammation and tissue damage associated with Alzheimer's disease are unclear. Golenbock and colleagues now show that amyloid-β activates the NALP3 inflammasome, which triggers the release of proinflammatory and neurotoxic factors. The fibrillar peptide amyloid-β (Aβ) has a chief function in the pathogenesis of Alzheimer's disease. Interleukin 1β (IL-1β) is a key cytokine in the inflammatory response to Aβ. Insoluble materials such as crystals activate the inflammasome formed by the cytoplasmic receptor NALP3, which results in the release of IL-1β. Here we identify the NALP3 inflammasome as a sensor of Aβ in a process involving the phagocytosis of Aβ and subsequent lysosomal damage and release of cathepsin B. Furthermore, the IL-1β pathway was essential for the microglial synthesis of proinflammatory and neurotoxic factors, and the inflammasome, caspase-1 and IL-1β were critical for the recruitment of microglia to exogenous Aβ in the brain. Our findings suggest that activation of the NALP3 inflammasome is important for inflammation and tissue damage in Alzheimer's disease.
2,053 citations
TL;DR: The interrelationships between Neuroinflammation and amyloid and tau pathologies as well as the effect of neuroinflammation on the disease trajectory in AD are discussed, focusing on microglia as major players in neuro inflammation and how these cells could be modulated as a therapeutic strategy for AD.
Abstract: Alzheimer disease (AD) is the most common form of neurodegenerative disease, estimated to contribute 60–70% of all cases of dementia worldwide. According to the prevailing amyloid cascade hypothesis, amyloid-β (Aβ) deposition in the brain is the initiating event in AD, although evidence is accumulating that this hypothesis is insufficient to explain many aspects of AD pathogenesis. The discovery of increased levels of inflammatory markers in patients with AD and the identification of AD risk genes associated with innate immune functions suggest that neuroinflammation has a prominent role in the pathogenesis of AD. In this Review, we discuss the interrelationships between neuroinflammation and amyloid and tau pathologies as well as the effect of neuroinflammation on the disease trajectory in AD. We specifically focus on microglia as major players in neuroinflammation and discuss the spatial and temporal variations in microglial phenotypes that are observed under different conditions. We also consider how these cells could be modulated as a therapeutic strategy for AD. Accumulating evidence indicates important roles for microglial activation and neuroinflammation in Alzheimer disease (AD). Here, Leng and Edison describe the interplay between microglial activation and AD-related pathologies and discuss how microglial priming and activation might influence the trajectory of AD.
859 citations
TL;DR: Overall, these data demonstrate that GSDMD is the direct and final executor of pyroptotic cell death.
Abstract: Pyroptosis is a lytic type of cell death that is initiated by inflammatory caspases. These caspases are activated within multi-protein inflammasome complexes that assemble in response to pathogens and endogenous danger signals. Pyroptotic cell death has been proposed to proceed via the formation of a plasma membrane pore, but the underlying molecular mechanism has remained unclear. Recently, gasdermin D (GSDMD), a member of the ill-characterized gasdermin protein family, was identified as a caspase substrate and an essential mediator of pyroptosis. GSDMD is thus a candidate for pyroptotic pore formation. Here, we characterize GSDMD function in live cells and in vitro We show that the N-terminal fragment of caspase-1-cleaved GSDMD rapidly targets the membrane fraction of macrophages and that it induces the formation of a plasma membrane pore. In vitro, the N-terminal fragment of caspase-1-cleaved recombinant GSDMD tightly binds liposomes and forms large permeability pores. Visualization of liposome-inserted GSDMD at nanometer resolution by cryo-electron and atomic force microscopy shows circular pores with variable ring diameters around 20 nm. Overall, these data demonstrate that GSDMD is the direct and final executor of pyroptotic cell death.
762 citations
TL;DR: In this paper, the authors used pre-clinical testing and appropriate selection of study participants to overcome the barriers to progress in acute ischemic stroke research, and proposed safe and effective treatment strategies that combine neuroprotection reperfusion, better use of advanced brain imaging for patient selection, and wider implementation of pre-hospital conducted clinical trials.
Abstract: Summary Treatments for acute ischaemic stroke continue to evolve after the superior value of endovascular thrombectomy was confirmed over systemic thrombolysis. Unfortunately, numerous neuroprotective drugs have failed to show benefit in the treatment of acute ischaemic stroke, making the search for new treatments imperative. Increased awareness of the relevance of rigorous preclinical testing, and appropriate selection of study participants, might overcome the barriers to progress in stroke research. Relevant areas of interest include the search for safe and effective treatment strategies that combine neuroprotection reperfusion, better use of advanced brain imaging for patient selection, and wider implementation of prehospital conducted clinical trials. Randomised controlled trials of combination treatments completed within the past 5 years have included growth factors, hypothermia, minocycline, natalizumab, fingolimod, and uric acid; the latter two drugs with alteplase produced encouraging results. Blocking of excitotoxicity is also being reassessed in clinical trials with new approaches, such as the postsynaptic density-95 inhibitor NA-1, or peritoneal dialysis to remove excess glutamate. The findings of these randomised trials are anticipated to improve treatment options and clinical outcomes in of patients with acute stroke.
742 citations