Mitochondria, oxidative metabolism and cell death in stroke
TL;DR: Pharmacological interventions and genetic modifications in rodent models strongly implicate caspase-dependent and caspases-independent apoptosis and the mitochondrial permeability transition as important contributors to tissue damage, particularly when induced by short periods of temporary focal ischemia.
About: This article is published in Biochimica et Biophysica Acta.The article was published on 2010-01-01 and is currently open access. It has received 624 citations till now. The article focuses on the topics: Mitochondrial permeability transition pore & Reperfusion injury.
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TL;DR: Evidence is provided that the NLRP1 and NLRP3 inflammasomes have a major role in neuronal cell death and behavioral deficits in stroke, and that IVIg treatment can protect brain cells against ischemic damage, suggesting a potential clinical benefit of therapeutic interventions that targetinflammasome assembly and activity.
Abstract: Multi-protein complexes called inflammasomes have recently been identified and shown to contribute to cell death in tissue injury. Intravenous immunoglobulin (IVIg) is an FDA-approved therapeutic modality used for various inflammatory diseases. The objective of this study is to investigate dynamic responses of the NLRP1 and NLRP3 inflammasomes in stroke and to determine whether the NLRP1 and NLRP3 inflammasomes can be targeted with IVIg for therapeutic intervention. Primary cortical neurons were subjected to glucose deprivation (GD), oxygen–glucose deprivation (OGD) or simulated ischemia-reperfusion (I/R). Ischemic stroke was induced in C57BL/6J mice by middle cerebral artery occlusion, followed by reperfusion. Neurological assessment was performed, brain tissue damage was quantified, and NLRP1 and NLRP3 inflammasome protein levels were evaluated. NLRP1 and NLRP3 inflammasome components were also analyzed in postmortem brain tissue samples from stroke patients. Ischemia-like conditions increased the levels of NLRP1 and NLRP3 inflammasome proteins, and IL-1β and IL-18, in primary cortical neurons. Similarly, levels of NLRP1 and NLRP3 inflammasome proteins, IL-1β and IL-18 were elevated in ipsilateral brain tissues of cerebral I/R mice and stroke patients. Caspase-1 inhibitor treatment protected cultured cortical neurons and brain cells in vivo in experimental stroke models. IVIg treatment protected neurons in experimental stroke models by a mechanism involving suppression of NLRP1 and NLRP3 inflammasome activity. Our findings provide evidence that the NLRP1 and NLRP3 inflammasomes have a major role in neuronal cell death and behavioral deficits in stroke. We also identified NLRP1 and NLRP3 inflammasome inhibition as a novel mechanism by which IVIg can protect brain cells against ischemic damage, suggesting a potential clinical benefit of therapeutic interventions that target inflammasome assembly and activity.
399 citations
TL;DR: The NVU system offers an in vitro approach for probing transport, efficacy, mechanism of action and toxicity of neuroactive drugs, and to identify previously unknown metabolic coupling between the BBB and neurons.
Abstract: The neurovascular unit (NVU) regulates metabolic homeostasis as well as drug pharmacokinetics and pharmacodynamics in the central nervous system. Metabolic fluxes and conversions over the NVU rely on interactions between brain microvascular endothelium, perivascular pericytes, astrocytes and neurons, making it difficult to identify the contributions of each cell type. Here we model the human NVU using microfluidic organ chips, allowing analysis of the roles of individual cell types in NVU functions. Three coupled chips model influx across the blood-brain barrier (BBB), the brain parenchymal compartment and efflux across the BBB. We used this linked system to mimic the effect of intravascular administration of the psychoactive drug methamphetamine and to identify previously unknown metabolic coupling between the BBB and neurons. Thus, the NVU system offers an in vitro approach for probing transport, efficacy, mechanism of action and toxicity of neuroactive drugs.
284 citations
TL;DR: Using a mouse hippocampal brain slice model of cerebral ischemia, it is shown that ceria nanoparticles reduce ischemic cell death by approximately 50% and suggests that scavenging of peroxynitrite may be an important mechanism by which cerium oxide nanoparticles mitigate isChemic brain injury.
248 citations
TL;DR: An overview of some of the molecular mechanisms and potential therapies involved in the alteration of cellular energetics with aging and injury with a neurobiological perspective is provided.
229 citations
TL;DR: The involvement of mitochondrial (dys)function in various neurological disorders is described and the putative link between mitochondrial function and neuroinflammation is discussed.
214 citations
Cites background from "Mitochondria, oxidative metabolism ..."
...stroke-related research (for review, see Niizuma et al., 2009; Sims and Muyderman, 2010), as mitochondrial changes following glu-...
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...Mitochondria are and have been the focus of a vast amount of stroke-related research (for review, see Niizuma et al., 2009; Sims and Muyderman, 2010), as mitochondrial changes following glucose–oxygen deprivation, such as decreased ATP production and increased ROS production, contribute to…...
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References
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TL;DR: The basic components of the death machinery are reviewed, how they interact to regulate apoptosis in a coordinated manner is described, and the main pathways that are used to activate cell death are discussed.
Abstract: Apoptosis - the regulated destruction of a cell - is a complicated process. The decision to die cannot be taken lightly, and the activity of many genes influence a cell's likelihood of activating its self-destruction programme. Once the decision is taken, proper execution of the apoptotic programme requires the coordinated activation and execution of multiple subprogrammes. Here I review the basic components of the death machinery, describe how they interact to regulate apoptosis in a coordinated manner, and discuss the main pathways that are used to activate cell death.
7,255 citations
TL;DR: Once MMP has been induced, it causes the release of catabolic hydrolases and activators of such enzymes (including those of caspases) from mitochondria, meaning that mitochondria coordinate the late stage of cellular demise.
Abstract: Irrespective of the morphological features of end-stage cell death (that may be apoptotic, necrotic, autophagic, or mitotic), mitochondrial membrane permeabilization (MMP) is frequently the decisive event that delimits the frontier between survival and death. Thus mitochondrial membranes constitute the battleground on which opposing signals combat to seal the cell's fate. Local players that determine the propensity to MMP include the pro- and antiapoptotic members of the Bcl-2 family, proteins from the mitochondrialpermeability transition pore complex, as well as a plethora of interacting partners including mitochondrial lipids. Intermediate metabolites, redox processes, sphingolipids, ion gradients, transcription factors, as well as kinases and phosphatases link lethal and vital signals emanating from distinct subcellular compartments to mitochondria. Thus mitochondria integrate a variety of proapoptotic signals. Once MMP has been induced, it causes the release of catabolic hydrolases and activators of such enzymes (including those of caspases) from mitochondria. These catabolic enzymes as well as the cessation of the bioenergetic and redox functions of mitochondria finally lead to cell death, meaning that mitochondria coordinate the late stage of cellular demise. Pathological cell death induced by ischemia/reperfusion, intoxication with xenobiotics, neurodegenerative diseases, or viral infection also relies on MMP as a critical event. The inhibition of MMP constitutes an important strategy for the pharmaceutical prevention of unwarranted cell death. Conversely, induction of MMP in tumor cells constitutes the goal of anticancer chemotherapy.
3,340 citations
"Mitochondria, oxidative metabolism ..." refers background in this paper
...IAPs inhibit caspase-3, caspase-7 and caspase-9....
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...Endonuclease G, another protein released from mitochondria, can interact with AIF under some conditions and can directly cause caspase-independent apoptosis [3,25,26]....
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...Interactions of AIF with the protein, cyclophin A in the cytosol and co-translocation of the two proteins lead to DNA degradation [3,25,26,100]....
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...1), which result from mitochondrial release of apoptosis inducing factor (AIF) and perhaps other proteins [3,25,26], have also been implicated in focal ischemic damage (see section 5....
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...Omi/HtrA2 but not Smac/DIABLO has a proteolytic activity that contributes to the inhibitory effects on IAPs [3,25]....
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TL;DR: Cyclophilin D and the mitochondrial permeability transition are required for mediating Ca2+- and oxidative damage-induced cell death, but not Bcl-2 family member-regulated death.
Abstract: Mitochondria play a critical role in mediating both apoptotic and necrotic cell death. The mitochondrial permeability transition (mPT) leads to mitochondrial swelling, outer membrane rupture and the release of apoptotic mediators. The mPT pore is thought to consist of the adenine nucleotide translocator, a voltage-dependent anion channel, and cyclophilin D (the Ppif gene product), a prolyl isomerase located within the mitochondrial matrix. Here we generated mice lacking Ppif and mice overexpressing cyclophilin D in the heart. Ppif null mice are protected from ischaemia/reperfusion-induced cell death in vivo, whereas cyclophilin D-overexpressing mice show mitochondrial swelling and spontaneous cell death. Mitochondria isolated from the livers, hearts and brains of Ppif null mice are resistant to mitochondrial swelling and permeability transition in vitro. Moreover, primary hepatocytes and fibroblasts isolated from Ppif null mice are largely protected from Ca2+-overload and oxidative stress-induced cell death. However, Bcl-2 family member-induced cell death does not depend on cyclophilin D, and Ppif null fibroblasts are not protected from staurosporine or tumour-necrosis factor-alpha-induced death. Thus, cyclophilin D and the mitochondrial permeability transition are required for mediating Ca2+- and oxidative damage-induced cell death, but not Bcl-2 family member-regulated death.
2,131 citations
TL;DR: The results indicate that the CypD-dependent mPT regulates some forms of necrotic death, but not apoptotic death, as indicated by resistance to ischaemia/reperfusion-induced cardiac injury.
Abstract: Mitochondria play an important role in energy production, Ca2+ homeostasis and cell death. In recent years, the role of the mitochondria in apoptotic and necrotic cell death has attracted much attention. In apoptosis and necrosis, the mitochondrial permeability transition (mPT), which leads to disruption of the mitochondrial membranes and mitochondrial dysfunction, is considered to be one of the key events, although its exact role in cell death remains elusive. We therefore created mice lacking cyclophilin D (CypD), a protein considered to be involved in the mPT, to analyse its role in cell death. CypD-deficient mice were developmentally normal and showed no apparent anomalies, but CypD-deficient mitochondria did not undergo the cyclosporin A-sensitive mPT. CypD-deficient cells died normally in response to various apoptotic stimuli, but showed resistance to necrotic cell death induced by reactive oxygen species and Ca2+ overload. In addition, CypD-deficient mice showed a high level of resistance to ischaemia/reperfusion-induced cardiac injury. Our results indicate that the CypD-dependent mPT regulates some forms of necrotic death, but not apoptotic death.
1,525 citations
TL;DR: It is suggested that the limited survival of the penumbra is due to periinfarct depolarizations, which result in repeated episodes of tissue hypoxia, because the increased metabolic workload is not coupled to an adequate increase of collateral blood supply.
Abstract: The classic concept of the viability thresholds of ischemia differentiates between two critical flow rates, the threshold of electrical failure and the threshold of membrane failure. These thresholds mark the upper and lower flow limits of the ischemic penumbra which is thought ot suffer only functional but not structural injury. Recent studies of the functional and metabolic disturbances suggest a more complex pattern of thresholds. At declining flow rates, protein synthesis is inhibited at first (at a threshold of about 0.55 ml/gm/min), followed by a stimulation of anaerobic glycolysis (at 0.35 ml/gm/min), the release of neurotransmitters and the beginning disturbance of energy metabolism (at about 0.20 ml/min), and finally the anoxic depolariztion (<0.15 ml/gm/min). The penumbra, as defined by the classic flow thresholds, does not remain viable for extended periods. Since viability of the tissue requires maintenance of energy-dependent metabolic processes, penumbra is redefined as a region of constrained blood supply in which the energy metabolism is preserved. Imaging of the penumbra by combining autoradiographic cerebral blood flow measurements with bioluminescent images of adenosine triphosphate (ATP) demonstrates a gradual expansion of the infarct core (in which ATP is depleted) into the penumbra until, after a few hours, the penumbra has disappeared. It is suggested that the limited survival of the penumbra is due to periinfarct depolarizations, which result in repeated episodes of tissue hypoxia, because the increased metabolic workload is not coupled to an adequate increase of collateral blood supply. This explains pharmacological suppression of periinfarct depolarizations lowering the threshold of metabolic disturbances and reducing the volume of the ischemic infarct.
1,367 citations
"Mitochondria, oxidative metabolism ..." refers background in this paper
...This “penumbral” or “perifocal” tissue typically exhibits reductions to approximately 20–40% of normal flow [8,9,12]....
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...Neurons in the penumbra are electrically silent for long periods, a response associated with hyperpolarization of the plasma membrane [8,12]....
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