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Feng L, Sun J, Xia L, Shi Q, Hou Y, Zhang L, Li M, Fan C, Sun B. Ferroptosis mechanism and Alzheimer's disease. Neural Regen Res 2024; 19:1741-1750. [PMID: 38103240 PMCID: PMC10960301 DOI: 10.4103/1673-5374.389362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/05/2023] [Accepted: 09/09/2023] [Indexed: 12/18/2023] Open
Abstract
Regulated cell death is a genetically determined form of programmed cell death that commonly occurs during the development of living organisms. This process plays a crucial role in modulating homeostasis and is evolutionarily conserved across a diverse range of living organisms. Ferroptosis is a classic regulatory mode of cell death. Extensive studies of regulatory cell death in Alzheimer's disease have yielded increasing evidence that ferroptosis is closely related to the occurrence, development, and prognosis of Alzheimer's disease. This review summarizes the molecular mechanisms of ferroptosis and recent research advances in the role of ferroptosis in Alzheimer's disease. Our findings are expected to serve as a theoretical and experimental foundation for clinical research and targeted therapy for Alzheimer's disease.
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Affiliation(s)
- Lina Feng
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
| | - Jingyi Sun
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
| | - Ling Xia
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
| | - Qiang Shi
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
| | - Yajun Hou
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
| | - Lili Zhang
- Department of Internal Medicine, Taian Traffic Hospital, Taian, Shandong Province, China
| | - Mingquan Li
- Department of Neurology, the Third Affiliated Clinical Hospital of Changchun University of Chinese Medicine, Changchun, Jilin Province, China
| | - Cundong Fan
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
| | - Baoliang Sun
- Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control, the Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong Province, China
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2
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Tsering W, Prokop S. Neuritic Plaques - Gateways to Understanding Alzheimer's Disease. Mol Neurobiol 2024; 61:2808-2821. [PMID: 37940777 PMCID: PMC11043180 DOI: 10.1007/s12035-023-03736-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 10/21/2023] [Indexed: 11/10/2023]
Abstract
Extracellular deposits of amyloid-β (Aβ) in the form of plaques are one of the main pathological hallmarks of Alzheimer's disease (AD). Over the years, many different Aβ plaque morphologies such as neuritic plaques, dense cored plaques, cotton wool plaques, coarse-grain plaques, and diffuse plaques have been described in AD postmortem brain tissues, but correlation of a given plaque type with AD progression or AD symptoms is not clear. Furthermore, the exact trigger causing the development of one Aβ plaque morphological subtype over the other is still unknown. Here, we review the current knowledge about neuritic plaques, a subset of Aβ plaques surrounded by swollen or dystrophic neurites, which represent the most detrimental and consequential Aβ plaque morphology. Neuritic plaques have been associated with local immune activation, neuronal network dysfunction, and cognitive decline. Given that neuritic plaques are at the interface of Aβ deposition, tau aggregation, and local immune activation, we argue that understanding the exact mechanism of neuritic plaque formation is crucial to develop targeted therapies for AD.
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Affiliation(s)
- Wangchen Tsering
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, USA
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, USA
- McKnight Brain Institute, University of Florida, Gainesville, USA
| | - Stefan Prokop
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, USA.
- McKnight Brain Institute, University of Florida, Gainesville, USA.
- Department of Pathology, University of Florida, Gainesville, USA.
- Fixel Institute for Neurological Diseases, University of Florida, Gainesville, USA.
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Luo JJ, Wallace W, Kusiak JW. A tough trek in the development of an anti-amyloid therapy for Alzheimer's disease: Do we see hope in the distance? J Neurol Sci 2022; 438:120294. [DOI: 10.1016/j.jns.2022.120294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/27/2022] [Accepted: 05/18/2022] [Indexed: 12/17/2022]
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4
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Streit WJ, Rotter J, Winter K, Müller W, Khoshbouei H, Bechmann I. Droplet Degeneration of Hippocampal and Cortical Neurons Signifies the Beginning of Neuritic Plaque Formation. J Alzheimers Dis 2021; 85:1701-1720. [PMID: 34958037 DOI: 10.3233/jad-215334] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Neuritic plaques contain neural and microglial elements, and amyloid-β protein (Aβ), but their pathogenesis remains unknown. OBJECTIVE Elucidate neuritic plaque pathogenesis. METHODS Histochemical visualization of hyperphosphorylated-tau positive (p-tau+) structures, microglia, Aβ, and iron. RESULTS Disintegration of large projection neurons in human hippocampus and neocortex presents as droplet degeneration: pretangle neurons break up into spheres of numerous p-tau+ droplets of various sizes, which marks the beginning of neuritic plaques. These droplet spheres develop in the absence of colocalized Aβ deposits but once formed become encased in diffuse Aβ with great specificity. In contrast, neurofibrillary tangles often do not colocalize with Aβ. Double-labelling for p-tau and microglia showed a lack of microglial activation or phagocytosis of p-tau+ degeneration droplets but revealed massive upregulation of ferritin in microglia suggesting presence of high levels of free iron. Perl's Prussian blue produced positive staining of microglia, droplet spheres, and Aβ plaque cores supporting the suggestion that droplet degeneration of pretangle neurons in the hippocampus and cortex represents ferroptosis, which is accompanied by the release of neuronal iron extracellularly. CONCLUSION Age-related iron accumulation and ferroptosis in the CNS likely trigger at least two endogenous mechanisms of neuroprotective iron sequestration and chelation, microglial ferritin expression and Aβ deposition, respectively, both contributing to the formation of neuritic plaques. Since neurofibrillary tangles and Aβ deposits colocalize infrequently, tangle formation likely does not involve release of neuronal iron extracellularly. In human brain, targeted deposition of Aβ occurs specifically in response to ongoing ferroptotic droplet degeneration thereby producing neuritic plaques.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, USA
| | - Jonas Rotter
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Karsten Winter
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Wolf Müller
- Department of Neuropathology, Leipzig University, Leipzig, Germany
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, USA
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, Germany
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Huang YM, Hong XZ, Shen J, Geng LJ, Pan YH, Ling W, Zhao HL. Amyloids in Site-Specific Autoimmune Reactions and Inflammatory Responses. Front Immunol 2020; 10:2980. [PMID: 31993048 PMCID: PMC6964640 DOI: 10.3389/fimmu.2019.02980] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 12/04/2019] [Indexed: 12/15/2022] Open
Abstract
Amyloid deposition is a histological hallmark of common human disorders including Alzheimer's disease (AD) and type 2 diabetes. Although some reports highlight that amyloid fibrils might activate the innate immunity system via pattern recognition receptors, here, we provide multiple lines of evidence for the protection by site-specific amyloid protein analogs and fibrils against autoimmune attacks: (1) strategies targeting clearance of the AD-related brain amyloid plaque induce high risk of deadly autoimmune destructions in subjects with cognitive dysfunction; (2) administration of amyloidogenic peptides with either full length or core hexapeptide structure consistently ameliorates signs of experimental autoimmune encephalomyelitis; (3) experimental autoimmune encephalomyelitis is exacerbated following genetic deletion of amyloid precursor proteins; (4) absence of islet amyloid coexists with T-cell-mediated insulitis in autoimmune diabetes and autoimmune polyendocrine syndrome; (5) use of islet amyloid polypeptide agonists rather than antagonists improves diabetes care; and (6) common suppressive signaling pathways by regulatory T cells are activated in both local and systemic amyloidosis. These findings indicate dual modulation activity mediated by amyloid protein monomers, oligomers, and fibrils to maintain immune homeostasis. The protection from autoimmune destruction by amyloid proteins offers a novel therapeutic approach to regenerative medicine for common degenerative diseases.
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Affiliation(s)
- Yan-Mei Huang
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Center for Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin, China
| | - Xue-Zhi Hong
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Department of Rheumatology and Immunology, The First Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Jian Shen
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Department of Pathology, The First Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Li-Jun Geng
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Center for Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin, China
| | - Yan-Hong Pan
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Center for Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin, China
| | - Wei Ling
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Department of Endocrinology, Xiangya Medical School, Central South University, Changsha, China
| | - Hai-Lu Zhao
- Department of Immunology, Guangxi Area of Excellence, Guilin Medical University, Guilin, China.,Center for Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin, China.,Institute of Basic Medical Sciences, Faculty of Basic Medicine, Guilin Medical University, Guilin, China
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Ceylan H, Budak H, Kocpinar EF, Baltaci NG, Erdogan O. Examining the link between dose-dependent dietary iron intake and Alzheimer's disease through oxidative stress in the rat cortex. J Trace Elem Med Biol 2019; 56:198-206. [PMID: 31525623 DOI: 10.1016/j.jtemb.2019.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/01/2019] [Accepted: 09/08/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Neurodegenerative diseases such as Alzheimer's and Parkinson's disease are characterized by the progressive deterioration of the structure and function of the nervous system. A number of environmental risk factors including potentially toxic elements such as iron, lead to negative effects on many metabolic reactions as well as neuroprotection. The aim of this study is to reveal whether long-term iron overload is one of the underlying factors in the pathogenesis of Alzheimer's disease (AD). METHODS 15 young-adult male rats were randomly divided into 5 groups treated with iron through drinking water for 4 months. Following feeding, the iron content, reduced glutathione (GSH), and hydrogen peroxide (H2O2) levels of cortex tissues were measured. Specific enzyme activities were determined spectrophotometrically. mRNA expression profiles were measured using real-time PCR (qPCR). RESULTS Iron levels were elevated in case of non-toxic (0.87 and 3 μg/mL) iron administration. However, no changes were observed in toxic (30 and 300 μg/mL) iron administration. GSH and H2O2 levels altered with long-term iron overload. Glutathione peroxidase (GPx) enzyme activities significantly increased in all groups, while glutathione S-transferase (GST) activity increased only in case of 0.87 and 30 μg/mL iron administration. Expression levels of neuroprotective and AD-related genes were altered by 3 μg/mL iron overload in a dose-dependent manner. The expression and activity of acetylcholinesterase (AChE) were elevated at 3 μg/mL iron concentration. CONCLUSION The findings of the present study allow us to conclude that long-term dietary iron intake, especially at a dose of 3 μg/mL demonstrates negative effects on the rat cortex by provoking antioxidant metabolism and AD pathology in a dose-dependently.
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Affiliation(s)
- Hamid Ceylan
- Science Faculty, Department of Molecular Biology and Genetics, Atatürk University, Erzurum, Turkey.
| | - Harun Budak
- Science Faculty, Department of Molecular Biology and Genetics, Atatürk University, Erzurum, Turkey
| | - Enver Fehim Kocpinar
- Science Faculty, Department of Molecular Biology and Genetics, Atatürk University, Erzurum, Turkey; Vocational School, Department of Medical Services and Techniques, Muş Alparslan University, Mus, Turkey
| | - Nurdan Gonul Baltaci
- Science Faculty, Department of Molecular Biology and Genetics, Atatürk University, Erzurum, Turkey
| | - Orhan Erdogan
- Science Faculty, Department of Molecular Biology and Genetics, Atatürk University, Erzurum, Turkey
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8
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Teller S, Tahirbegi IB, Mir M, Samitier J, Soriano J. Magnetite-Amyloid-β deteriorates activity and functional organization in an in vitro model for Alzheimer's disease. Sci Rep 2015; 5:17261. [PMID: 26608215 PMCID: PMC4660300 DOI: 10.1038/srep17261] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/26/2015] [Indexed: 11/09/2022] Open
Abstract
The understanding of the key mechanisms behind human brain deterioration in Alzheimer' disease (AD) is a highly active field of research. The most widespread hypothesis considers a cascade of events initiated by amyloid-β peptide fibrils that ultimately lead to the formation of the lethal amyloid plaques. Recent studies have shown that other agents, in particular magnetite, can also play a pivotal role. To shed light on the action of magnetite and amyloid-β in the deterioration of neuronal circuits, we investigated their capacity to alter spontaneous activity patterns in cultured neuronal networks. Using a versatile experimental platform that allows the parallel monitoring of several cultures, the activity in controls was compared with the one in cultures dosed with magnetite, amyloid-β and magnetite-amyloid-β complex. A prominent degradation in spontaneous activity was observed solely when amyloid-β and magnetite acted together. Our work suggests that magnetite nanoparticles have a more prominent role in AD than previously thought, and may bring new insights in the understanding of the damaging action of magnetite-amyloid-β complex. Our experimental system also offers new interesting perspectives to explore key biochemical players in neurological disorders through a controlled, model system manner.
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Affiliation(s)
- Sara Teller
- Departament d’Estructura i Constituents de la Matèria, Universitat de Barcelona, Barcelona, E-08028, Spain
| | - Islam Bogachan Tahirbegi
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, E-08028, Spain
- Departament d’Electrònica, Universitat de Barcelona, Barcelona, E-08028, Spain
| | - Mònica Mir
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, E-08028, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, E-08028, Spain
| | - Josep Samitier
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, E-08028, Spain
- Departament d’Electrònica, Universitat de Barcelona, Barcelona, E-08028, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, E-08028, Spain
| | - Jordi Soriano
- Departament d’Estructura i Constituents de la Matèria, Universitat de Barcelona, Barcelona, E-08028, Spain
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Purushothuman S, Stone J. The reaction of cerebral cortex to a nearby lesion: damage, survival, self-protection. Brain Res 2015; 1601:52-63. [PMID: 25591482 DOI: 10.1016/j.brainres.2015.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/02/2015] [Indexed: 01/13/2023]
Abstract
A needlestick injury to cerebral cortex causes immediate damage along the track of the needle (haemorrhage, cell death) and sequelae (the formation of amyloid-positive plaques, extracellular deposits of hyperphosphorylated tau protein, microglial proliferation, astrogliosis) that are long lasting, and mimic the neuropathology associated with Alzheimer's disease. We report here that the same injury also elicits a distinctive response in the cortex flanking (up to 1mm from) the direct injury. Needlestick injury was made in the neo- and hippocampal cortex of young (3 months) healthy Sprague-Dawley rats. After survival times of up to 7d, the response of the cortex was assessed with histology, immunohistochemistry and stereology. Uptake of FluoroJade B at 1d survival and labelling for 4-hydroxynonenal (4-HNE) gave measures of membrane damage; labelling for 8-hydroxy-2'-deoxyguanosine (8-OHDG) gave a measure of DNA damage, and labelling with the AT8 antibody gave a measure of the hyperphosphorylation of tau. Two probes, for neuroglobin and basic fibroblast growth factor (FGF-2), gave measures of a self-protective response in the tissue. Results indicate that neurones in the flanking region are damaged by the nearby lesion, and within 1d upregulate self-protective mechanisms. Over the next 6d survival, evidence of neuronal damage reduces markedly. In summary, cells in the region flanking a lesion are stressed by the lesion, and react to the stress with a self-protective response, which prevents their death. This response may be an important, previously unrecognised feature of brain tissue close to a focus of stress, such as a microhaemorrhage.
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Affiliation(s)
- Sivaraman Purushothuman
- Discipline of Physiology and Bosch Institute, School of Medical Sciences, Faculty of Medicine, The University of Sydney, Camperdown, NSW 2006, Australia; Discipline of Clinical Ophthalmology & Save Sight Institute, The University of Sydney & Sydney Eye Hospital, Sydney NSW 2000, Australia.
| | - Jonathan Stone
- Discipline of Physiology and Bosch Institute, School of Medical Sciences, Faculty of Medicine, The University of Sydney, Camperdown, NSW 2006, Australia.
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Musunuri S, Wetterhall M, Ingelsson M, Lannfelt L, Artemenko K, Bergquist J, Kultima K, Shevchenko G. Quantification of the brain proteome in Alzheimer's disease using multiplexed mass spectrometry. J Proteome Res 2014; 13:2056-68. [PMID: 24606058 DOI: 10.1021/pr401202d] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We have compared the brain proteome in the temporal neocortex between Alzheimer's disease (AD) patients and non-AD individuals by using shotgun mass spectrometry based on a stable isotope dimethyl labeling. A total of 827 unique proteins were identified and quantitated. Of these, 227 proteins were found in at least 9 out of 10 AD/control pairs and were further subjected to statistical analysis. A total of 69 proteins showed different levels (p-value < 0.05) in AD versus control brain samples. Of these proteins, 37 were increased and 32 were decreased as compared to the non-AD subjects. Twenty-three proteins comprise novel proteins that have not previously been reported as related to AD, e.g., neuronal-specific septin-3, septin-2, septin-5, dihydropteridine reductase, and clathrin heavy chain 1. The proteins with altered levels in the AD brain represent a wide variety of pathways suggested to be involved in the disease pathogenesis, including energy metabolism, glycolysis, oxidative stress, apoptosis, signal transduction, and synaptic functioning. Apart from leading to new insights into the molecular mechanisms in AD, the findings provide us with possible novel candidates for future diagnostic and prognostic disease markers.
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Affiliation(s)
- Sravani Musunuri
- Analytical Chemistry, Department of Chemistry-BMC and ‡Department Public Health/Geriatrics, Uppsala University , Uppsala, Sweden
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Gilbert BJ. Republished: The role of amyloid β in the pathogenesis of Alzheimer's disease. Postgrad Med J 2014; 90:113-7. [DOI: 10.1136/postgradmedj-2013-201515rep] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Raha AA, Vaishnav RA, Friedland RP, Bomford A, Raha-Chowdhury R. The systemic iron-regulatory proteins hepcidin and ferroportin are reduced in the brain in Alzheimer's disease. Acta Neuropathol Commun 2013; 1:55. [PMID: 24252754 PMCID: PMC3893417 DOI: 10.1186/2051-5960-1-55] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 08/25/2013] [Indexed: 12/11/2022] Open
Abstract
Background The pathological features of the common neurodegenerative conditions, Alzheimer’s disease (AD), Parkinson’s disease and multiple sclerosis are all known to be associated with iron dysregulation in regions of the brain where the specific pathology is most highly expressed. Iron accumulates in cortical plaques and neurofibrillary tangles in AD where it participates in redox cycling and causes oxidative damage to neurons. To understand these abnormalities in the distribution of iron the expression of proteins that maintain systemic iron balance was investigated in human AD brains and in the APP-transgenic (APP-tg) mouse. Results Protein levels of hepcidin, the iron-homeostatic peptide, and ferroportin, the iron exporter, were significantly reduced in hippocampal lysates from AD brains. By histochemistry, hepcidin and ferroportin were widely distributed in the normal human brain and co-localised in neurons and astrocytes suggesting a role in regulating iron release. In AD brains, hepcidin expression was reduced and restricted to the neuropil, blood vessels and damaged neurons. In the APP-tg mouse immunoreactivity for ferritin light-chain, the iron storage isoform, was initially distributed throughout the brain and as the disease progressed accumulated in the core of amyloid plaques. In human and mouse tissues, extensive AD pathology with amyloid plaques and severe vascular damage with loss of pericytes and endothelial disruption was seen. In AD brains, hepcidin and ferroportin were associated with haem-positive granular deposits in the region of damaged blood vessels. Conclusion Our results suggest that the reduction in ferroportin levels are likely associated with cerebral ischaemia, inflammation, the loss of neurons due to the well-characterised protein misfolding, senile plaque formation and possibly the ageing process itself. The reasons for the reduction in hepcidin levels are less clear but future investigation could examine circulating levels of the peptide in AD and a possible reduction in the passage of hepcidin across damaged vascular endothelium. Imbalance in the levels and distribution of ferritin light-chain further indicate a failure to utilize and release iron by damaged and degenerating neurons.
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Abstract
The amyloid-β peptide (Aβ) is widely considered to be the major toxic agent in the pathogenesis of Alzheimer's disease, a condition which afflicts approximately 36 million people worldwide. Despite a plethora of studies stretching back over two decades, identifying the toxic Aβ species has proved difficult. Debate has centred on the Aβ fibril and oligomer. Despite support from numerous experimental models, important questions linger regarding the role of the Aβ oligomer in particular. It is likely a huge array of oligomers, rather than a single species, which cause toxicity. Reappraisal of the role of the Aβ fibril points towards a dynamic relationship with the Aβ oligomer within an integrated system, as supported by evidence from microglia. However, some continue to doubt the pathological role of amyloid β, instead proposing a protective role. If the field is to progress, all Aβ oligomers should be characterised, the nomenclature revised and a consistent experimental protocol defined. For this to occur, collaboration will be required between major research groups and innovative analytical tools developed. Such action must surely be taken if amyloid-based therapeutic endeavour is to progress.
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Affiliation(s)
- Barnabas James Gilbert
- Medical Sciences Division, University of Oxford, Green Templeton College, 43 Woodstock Road, Summertown, Oxford OX2 6HG, UK.
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Sinha M, Bhowmick P, Banerjee A, Chakrabarti S. Antioxidant role of amyloid β protein in cell-free and biological systems: implication for the pathogenesis of Alzheimer disease. Free Radic Biol Med 2013; 56:184-92. [PMID: 23041348 DOI: 10.1016/j.freeradbiomed.2012.09.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 09/11/2012] [Accepted: 09/26/2012] [Indexed: 01/11/2023]
Abstract
In contrast to many studies showing the pro-oxidative nature of amyloid peptide, this work shows that aggregated Aβ42 peptide in varying concentrations (2-20 μM) in cell-free systems inhibits the formation of hydroxyl radicals and H(2)O(2) from a mixture of iron (20 μM FeSO(4)) and ascorbate (2mM) as measured by benzoate hydroxylation assay and coumarin carboxylic acid assay. Aggregated Aβ42 in similar concentrations further prevents protein and lipid oxidation in isolated rat brain mitochondria incubated alone or with FeSO(4) and ascorbate. Moreover, mitochondria exposed to FeSO(4) and ascorbate show enhanced formation of reactive oxygen species and this phenomenon is also abolished by aggregated Aβ42. It is suggested that the antioxidant property of Aβ42 in various systems is mediated by metal chelation and it is nearly as potent as a typical metal chelator, such as diethylenetriaminepentaacetic acid, in preventing oxidative damage. However, aggregated Aβ42 causes mitochondrial functional impairment in the form of membrane depolarization and a loss of phosphorylation capacity without involving reactive oxygen species in the process. Thus, the present results suggest that the amyloid peptide exhibits a protective antioxidant role in biological systems, but also has toxic actions independent of oxidative stress.
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Affiliation(s)
- Maitrayee Sinha
- Department of Biochemistry, Institute of Post Graduate Medical Education & Research, Kolkata 700 020, India
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15
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Coordination of redox active metal ions to the amyloid precursor protein and to amyloid-β peptides involved in Alzheimer disease. Part 1: An overview. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.03.037] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Chuang JY, Lee CW, Shih YH, Yang T, Yu L, Kuo YM. Interactions between amyloid-β and hemoglobin: implications for amyloid plaque formation in Alzheimer's disease. PLoS One 2012; 7:e33120. [PMID: 22412990 PMCID: PMC3295782 DOI: 10.1371/journal.pone.0033120] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 02/10/2012] [Indexed: 02/05/2023] Open
Abstract
Accumulation of amyloid-β (Aβ) peptides in the brain is one of the central pathogenic events in Alzheimer's disease (AD). However, why and how Aβ aggregates within the brain of AD patients remains elusive. Previously, we demonstrated hemoglobin (Hb) binds to Aβ and co-localizes with the plaque and vascular amyloid deposits in post-mortem AD brains. In this study, we further characterize the interactions between Hb and Aβ in vitro and in vivo and report the following observations: 1) the binding of Hb to Aβ required iron-containing heme; 2) other heme-containing proteins, such as myoglobin and cytochrome C, also bound to Aβ; 3) hemin-induced cytotoxicity was reduced in neuroblastoma cells by low levels of Aβ; 4) Hb was detected in neurons and glial cells of post-mortem AD brains and was up-regulated in aging and APP/PS1 transgenic mice; 5) microinjection of human Hb into the dorsal hippocampi of the APP/PS1 transgenic mice induced the formation of an envelope-like structure composed of Aβ surrounding the Hb droplets. Our results reveal an enhanced endogenous expression of Hb in aging brain cells, probably serving as a compensatory mechanism against hypoxia. In addition, Aβ binds to Hb and other hemoproteins via the iron-containing heme moiety, thereby reducing Hb/heme/iron-induced cytotoxicity. As some of the brain Hb could be derived from the peripheral circulation due to a compromised blood-brain barrier frequently observed in aged and AD brains, our work also suggests the genesis of some plaques may be a consequence of sustained amyloid accretion at sites of vascular injury.
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Affiliation(s)
- Jia-Ying Chuang
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Chu-Wan Lee
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yao-Hsiang Shih
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Tingting Yang
- Division of Neuroscience and Neuropathology, The School of Chinese Medicine for Post-Baccalaureate, I-Shou University, Kaohsiung, Taiwan
| | - Lung Yu
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
- Institute of Behavioral Medicine, National Cheng Kung University, Tainan, Taiwan
- * E-mail: (LY); (YK)
| | - Yu-Min Kuo
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
- Department of Cell Biology and Anatomy, National Cheng Kung University, Tainan, Taiwan
- * E-mail: (LY); (YK)
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Mir M, Tahirbegi IB, Valle-Delgado JJ, Fernàndez-Busquets X, Samitier J. In vitro study of magnetite-amyloid β complex formation. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2011; 8:974-80. [PMID: 22115601 DOI: 10.1016/j.nano.2011.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 10/28/2011] [Accepted: 11/11/2011] [Indexed: 01/31/2023]
Abstract
Biogenic magnetite (Fe(3)O(4)) has been identified in human brain tissue. However, abnormal concentration of magnetite nanoparticles in the brain has been observed in different neurodegenerative pathologies. In the case of Alzheimer's disease (AD), these magnetic nanoparticles have been identified attached to the characteristic brain plaques, which are mainly formed by fibrils of amyloid β peptide (Aβ). However, few clues about the formation of the magnetite-Aβ complex have been reported. We have investigated the interaction between these important players in AD with superconducting quantum interference, scanning electron microscope, surface plasmon resonance, and magnetic force microscopy. The results support the notion that the magnetite-Aβ complex is created before the synthesis of the magnetic nanoparticles, bringing a highly stable interaction of this couple. .
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Affiliation(s)
- Mònica Mir
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.
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18
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Bousejra-ElGarah F, Bijani C, Coppel Y, Faller P, Hureau C. Iron(II) binding to amyloid-β, the Alzheimer's peptide. Inorg Chem 2011; 50:9024-30. [PMID: 21800824 DOI: 10.1021/ic201233b] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Iron has been implicated in Alzheimer's disease, but until now no direct proof of Fe(II) binding to the amyloid-β peptide (Aβ) has been reported. We used NMR to evidence Fe(II) coordination to full-length Aβ40 and truncated Aβ16 peptides at physiological pH and to show that the Fe(II) binding site is located in the first 16 amino-acid residues. Fe(II) caused selective broadening of some NMR peaks that was dependent on the Fe:Aβ stoichiometry and temperature. Analysis of Fe(II) broadening effect in the (1)H, (13)C, and 2D NMR data established that Asp1, Glu3, the three His, but not Tyr10 nor Met35 are the residues mainly involved in Fe(II) coordination.
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Affiliation(s)
- Fatima Bousejra-ElGarah
- CNRS , LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, F-31077 Toulouse, France
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19
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Nunomura A, Tamaoki T, Tanaka K, Motohashi N, Nakamura M, Hayashi T, Yamaguchi H, Shimohama S, Lee HG, Zhu X, Smith MA, Perry G. Intraneuronal amyloid beta accumulation and oxidative damage to nucleic acids in Alzheimer disease. Neurobiol Dis 2009; 37:731-7. [PMID: 20034567 DOI: 10.1016/j.nbd.2009.12.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 11/26/2009] [Accepted: 12/14/2009] [Indexed: 01/21/2023] Open
Abstract
In an analysis of amyloid pathology in Alzheimer disease, we used an in situ approach to identify amyloid-beta (Abeta) accumulation and oxidative damage to nucleic acids in postmortem brain tissue of the hippocampal formation from subjects with Alzheimer disease. When carboxyl-terminal-specific antibodies directed against Abeta40 and Abeta42 were used for immunocytochemical analyses, Abeta42 was especially apparent within the neuronal cytoplasm, at sites not detected by the antibody specific to Abeta-oligomer. In comparison to the Abeta42-positive neurons, neurons bearing oxidative damage to nucleic acids were more widely distributed in the hippocampus. Comparative density measurements of the immunoreactivity revealed that levels of intraneuronal Abeta42 were inversely correlated with levels of intraneuronal 8-hydroxyguanosine, an oxidized nucleoside (r=- 0.61, p<0.02). Together with recent evidence that the Abeta peptide can act as an antioxidant, these results suggest that intraneuronal accumulation of non-oligomeric Abeta may be a compensatory response in neurons to oxidative stress in Alzheimer disease.
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Affiliation(s)
- Akihiko Nunomura
- Department of Neuropsychiatry, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
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20
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Cahill CM, Lahiri DK, Huang X, Rogers JT. Amyloid precursor protein and alpha synuclein translation, implications for iron and inflammation in neurodegenerative diseases. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1790:615-28. [PMID: 19166904 PMCID: PMC3981543 DOI: 10.1016/j.bbagen.2008.12.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 11/24/2008] [Accepted: 12/05/2008] [Indexed: 12/19/2022]
Abstract
Recent studies that alleles in the hemochromatosis gene may accelerate the onset of Alzheimer's disease by five years have validated interest in the model in which metals (particularly iron) accelerate disease course. Biochemical and biophysical measurements demonstrated the presence of elevated levels of neurotoxic copper zinc and iron in the brains of AD patients. Intracellular levels of APP holoprotein were shown to be modulated by iron by a mechanism that is similar to the translation control of the ferritin L- and H mRNAs by iron-responsive element (IRE) RNA stem loops in their 5' untranslated regions (5'UTRs). More recently a putative IRE-like sequence was hypothesized present in the Parkinsons's alpha synuclein (ASYN) transcript (see [A.L. Friedlich, R.E. Tanzi, J.T. Rogers, The 5'-untranslated region of Parkinson's disease alpha-synuclein messenger RNA contains a predicted iron responsive element, Mol. Psychiatry 12 (2007) 222-223. [6]]). Together with the demonstration of metal dependent translation of APP mRNA, the involvement of metals in the plaque of AD patients and of increased iron in striatal neurons in the substantia nigra (SN) of Parkinson's disease patients have stimulated the development of metal attenuating agents and iron chelators as a major new therapeutic strategy for the treatment of these neurodegenerative diseases. In the case of AD, metal based therapeutics may ultimately prove more cost effective than the use of an amyloid vaccine as the preferred anti-amyloid therapeutic strategy to ameliorate the cognitive decline of AD patients.
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Affiliation(s)
- Catherine M Cahill
- Neurochemistry Laboratory, Department of Psychiatry-Neuroscience, Massachusetts General Hospital (East), Harvard Medical School, CNY2, Building 149, Charlestown, MA 02129, USA
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21
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Castellani RJ, Zhu X, Lee HG, Smith MA, Perry G. Molecular pathogenesis of Alzheimer's disease: reductionist versus expansionist approaches. Int J Mol Sci 2009; 10:1386-1406. [PMID: 19399255 PMCID: PMC2672036 DOI: 10.3390/ijms10031386] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 03/20/2009] [Accepted: 03/23/2009] [Indexed: 12/17/2022] Open
Abstract
Alzheimer's disease (AD) is characterized clinically by dementia and pathologically by two hallmark lesions, senile plaques and neurofibrillary tangles. About a quarter century ago these hallmark lesions were purified and their protein constituents identified, precipitating an avalanche of molecular studies as well as substantial optimism about successful therapeutic intervention. In 2009, we now have copious knowledge on the biochemical cascades that produce these proteins, the different modifications and forms in which these proteins exist, and the ability to selectively target these proteins for therapeutic intervention on an experimental basis. At the same time, there has been no discernible alteration in the natural course of AD in humans. While it may be that the complexity of AD will exceed our capacity to make significant treatment progress for decades or more, a paradigm shift from the reductionism that defines amyloid-beta and tau hypotheses, to one that more accurately reflects the meaning of neuropathological changes, may be warranted. We and others have demonstrated that AD pathology is a manifestation of cellular adaptation, specifically as a defense against oxidative injury. As such, AD pathology is therefore a host response rather than a manifestation of cytotoxic protein injury, and is unlikely to be a fruitful target for therapeutic intervention. An "expansionist" view of the disease, we believe, with oxidative stress as a pleiotropic and upstream process, more aptly describes the relationship between various and numerous molecular alterations and clinical disease.
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Affiliation(s)
- Rudy J. Castellani
- Division of Neuropathology, University of Maryland, Baltimore, Maryland, USA
- Author to whom correspondence should be addressed; E-Mail:
| | - Xiongwei Zhu
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Hyoung-Gon Lee
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Mark A. Smith
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA
| | - George Perry
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA
- College of Sciences, University of Texas, San Antonio, Texas, USA
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22
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Abstract
PURPOSE OF REVIEW To explore the role of iron physiology in the brain of healthy adults and review how increased brain iron deposition has been associated with common neurodegenerative diseases that affect the elderly. RECENT FINDINGS Because iron plays a role in oxygen transportation, myelin synthesis, neurotransmitter production, and electron transfers, it serves as a crucial cofactor in normal central nervous metabolism. However, an increased level of brain iron may promote neurotoxicity due to free radical formation, lipid peroxidation, and ultimately, cellular death. Advanced neuroimaging techniques and pathological studies have demonstrated increased brain iron with aging, and increased iron deposition has also been observed in patients with a constellation of neurological diseases, including Alzheimer's disease, Parkinson's disease, and stroke. SUMMARY Pathologic and neurologic imaging coupled with experimentation have increased our understanding of the link between iron and neurodegeneration. A potential implication is that disease-modifying therapies aimed at removing excess iron may one day be part of the armamentarium employed by clinicians to decrease the burden of neurodegenerative diseases in the elderly.
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Affiliation(s)
- James M Stankiewicz
- Partners MS center, Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts 02445, USA.
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23
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Talmard C, Leuma Yona R, Faller P. Mechanism of zinc(II)-promoted amyloid formation: zinc(II) binding facilitates the transition from the partially alpha-helical conformer to aggregates of amyloid beta protein(1-28). J Biol Inorg Chem 2008; 14:449-55. [PMID: 19083027 DOI: 10.1007/s00775-008-0461-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 11/30/2008] [Indexed: 10/21/2022]
Abstract
The amyloidoses are a group of disorders characterized by aberrant protein folding and assembly, leading to the deposition of insoluble protein fibrils (amyloid), which provokes cell dysfunction and later cell death. One of the physiologically relevant environmental factors able to affect the conformation and hence the aggregation properties of amyloidogenic proteins/peptides is metal ions. Zn(II) promotes aggregation of most amyloidogenic peptides/proteins in vitro, including amyloid beta protein (Abeta), but the underlying mechanism is not known. To better understand this mechanism the present study focused on the partially alpha-helical conformer, supposed to be an intermediate in Abeta aggregation. This partially alpha-helical conformer is stabilized by 10-20% 2,2,2-trifluoroethanol (TFE): therefore, the influence of Zn binding on the aggregation of the amylidogenic model peptide Abeta(1-28) (Abeta28) was investigated at different TFE concentrations. The results showed a synergistic effect of Zn(II) and 10% TFE, i.e., that either Zn or 10% TFE accelerated Abeta28 aggregation on its own, but with them together an at least 10 times promotion of Abeta28 aggregation was observed. Further studies by thioflavin T fluorescence spectroscopy, transmission electron microscopy, and circular dichroism (CD) spectroscopy suggested that the aggregates of Zn-Abeta28 formed in 10%TFE contain a beta-sheet secondary structure and are more of the amyloid type. CD spectroscopy indicated that Zn binding disrupted partially the alpha-helical structure of Abeta28 in TFE. Thus, we propose that the promotion of Abeta28 aggregation by Zn is based on the transformation of the partially alpha-helical conformer (intermediate) towards the beta-sheet amyloid structure by a destabilization of the alpha-helix in the intermediate.
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Leuner K, Hauptmann S, Abdel-Kader R, Scherping I, Keil U, Strosznajder JB, Eckert A, Müller WE. Mitochondrial dysfunction: the first domino in brain aging and Alzheimer's disease? Antioxid Redox Signal 2007; 9:1659-75. [PMID: 17867931 DOI: 10.1089/ars.2007.1763] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
With the increasing average life span of humans and with decreasing cognitive function in elderly individuals, age-related cognitive disorders including dementia have become a major health problem in society. Aging-related mitochondrial dysfunction underlies many common neurodegenerative disorders diseases, including Alzheimer's disease (AD). AD is characterized by two major histopathological hallmarks, initially intracellular and with the progression of the disease extracellular accumulation of oligomeric and fibrillar beta-amyloid (Abeta) peptides and intracellular neurofibrillary tangles (NFT) composed of hyperphosphorylated tau protein. In this review, the authors focus on the latest findings in AD animal models indicating that these histopathological alterations induce deficits in the function of the complexes of the respiratory chain and therefore consecutively result in mitochondrial dysfunction. This parameter is intrinsically tied to oxidative stress. Both are early events in aging and especially in the pathogenesis of aging-related severe neurodegeneration. Ginkgo biloba extract seems to be of therapeutic benefit in the treatment of mild to moderate dementia of different etiology, although the data are quite heterogeneous. Herein, the authors suggest that mitochondrial protection and subsequent reduction of oxidative stress are important components of the neuroprotective activity of Ginkgo biloba extract.
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Affiliation(s)
- Kristina Leuner
- Department of Pharmacology, Zafes, Biocenter, University of Frankfurt, Germany.
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25
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Schenck JF, Zimmerman EA, Li Z, Adak S, Saha A, Tandon R, Fish KM, Belden C, Gillen RW, Barba A, Henderson DL, Neil W, O'Keefe T. High-field magnetic resonance imaging of brain iron in Alzheimer disease. Top Magn Reson Imaging 2007; 17:41-50. [PMID: 17179896 DOI: 10.1097/01.rmr.0000245455.59912.40] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVES Increased iron deposition in the brain may occur in several neurodegenerative diseases, including Alzheimer disease (AD). Iron deposits shorten T2 relaxation times on T2-weighted magnetic resonance (MR) images. Iron-dependent contrast increases with magnetic field strength. We hypothesized that T2 mapping using 3 T MR imaging (MRI) can disclose differences between normal controls and AD subjects. METHODS High-resolution brain imaging protocols were developed and applied to 24 AD patients and 20 age-matched controls using 3 T MRI. Eight anatomical regions of interest were manually segmented, and T2 histograms were computed. A visual analysis technique, the heat map, was modified and applied to the large image data sets generated by these protocols. RESULTS A large number (163) of features from these histograms were examined, and 38 of these were significantly different (P < 0.05) between the groups. In the hippocampus, evidence was found for AD-related increases in iron deposition (shortened T2) and in the concentration of free tissue water (lengthened T2). Imaging of a section of postmortem brain before and after chemically extracting the iron established the presence of MRI-detectable iron in the hippocampus, cortex, and white matter in addition to brain regions traditionally viewed as containing high iron concentrations.
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Affiliation(s)
- John F Schenck
- General Electric Global Research Center, Schenectady, NY 12309, USA.
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26
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Lee HG, Zhu X, Castellani RJ, Nunomura A, Perry G, Smith MA. Amyloid-β in Alzheimer Disease: The Null versus the Alternate Hypotheses. J Pharmacol Exp Ther 2007; 321:823-9. [PMID: 17229880 DOI: 10.1124/jpet.106.114009] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
For nearly 20 years, the primary focus for researchers studying Alzheimer disease has been centered on amyloid-beta, such that the amyloid cascade hypothesis has become the "null hypothesis." Indeed, amyloid-beta is, by the current definition of the disease, an obligate player in pathophysiology, is toxic to neurons in vitro, and, perhaps most compelling, is increased by all of the human genetic influences on the disease. Therefore, targeting amyloid-beta is the focus of considerable basic and therapeutic interest. However, an increasingly vocal group of investigators are arriving at an "alternate hypothesis" stating that amyloid-beta, while certainly involved in the disease, is not an initiating event but rather is secondary to other pathogenic events. Furthermore and perhaps most contrary to current thinking, the alternate hypothesis proposes that the role of amyloid-beta is not as a harbinger of death but rather a protective response to neuronal insult. To determine which hypothesis relates best to Alzheimer disease requires a broader view of disease pathogenesis and is discussed herein.
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Affiliation(s)
- Hyoung-gon Lee
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
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27
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Nunomura A, Castellani RJ, Zhu X, Moreira PI, Perry G, Smith MA. Involvement of oxidative stress in Alzheimer disease. J Neuropathol Exp Neurol 2006; 65:631-41. [PMID: 16825950 DOI: 10.1097/01.jnen.0000228136.58062.bf] [Citation(s) in RCA: 377] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Genetic and lifestyle-related risk factors for Alzheimer disease (AD) are associated with an increase in oxidative stress, suggesting that oxidative stress is involved at an early stage of the pathologic cascade. Moreover, oxidative stress is mechanistically and chronologically associated with other key features of AD, namely, metabolic, mitochondrial, metal, and cell-cycle abnormalities. Contrary to the commonly held notion that pathologic hallmarks of AD signify etiology, several lines of evidence now indicate that aggregation of amyloid-beta and tau is a compensatory response to underlying oxidative stress. Therefore, removal of proteinaceous accumulations may treat the epiphenomenon rather than the disease and may actually enhance oxidative damage. Although some antioxidants have been shown to reduce the incidence of AD, the magnitude of the effect may be modified by individual factors such as genetic predisposition (e.g. apolipoprotein E genotype) and habitual behaviors. Because caloric restriction, exercise, and intellectual activity have been experimentally shown to promote neuronal survival through enhancement of endogenous antioxidant defenses, a combination of dietary regimen of low total calorie and rich antioxidant nutrients and maintaining physical and intellectual activities may ultimately prove to be one of the most efficacious strategies for AD prevention.
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Affiliation(s)
- Akihiko Nunomura
- Department of Psychiatry and Neurology, Asahikawa Medical College, Asahikawa, Japan
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28
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Alzheimer' s disease, oxidative stress and gammahydroxybutyrate. Neurobiol Aging 2006; 28:1340-60. [PMID: 16837107 DOI: 10.1016/j.neurobiolaging.2006.06.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2006] [Revised: 05/14/2006] [Accepted: 06/12/2006] [Indexed: 12/21/2022]
Abstract
Although the cause of Alzheimer's disease is unknown, oxidative stress, energy depletion, excitotoxicity and vascular endothelial pathology are all considered to play a part in its pathogenesis. In reaction to these adverse events, the Alzheimer brain appears to deploy a highly conserved biological response to tissue stress. Oxidative metabolism is turned down, the expression of antioxidative enzymes is increased and intermediary metabolism is shifted in the direction of the pentose phosphate shunt to promote reductive detoxification, repair and biosynthesis. Gathering evidence suggests that the release of beta-amyloid and the formation of neurofibrillary tangles, the two hallmarks of Alzheimer's disease, are components of this protective response. Gammahydroxybutyrate (GHB), an endogenous short chain fatty acid, may be able to buttress this response. GHB can reduce glucose utilization, shift intermediary metabolism in the direction the pentose phosphate shunt and generate NADPH, a key cofactor in the activity of many antioxidative and reductive enzymes. GHB has been shown to spare cerebral energy utilization, block excitotoxicity and maintain vascular integrity in the face of impaired perfusion. Most important, GHB has repeatedly been shown to prevent the tissue damaging effects of oxidative stress. It may therefore be possible to utilize GHB to strengthen the brain's innate defences against the pathological processes operating in the Alzheimer brain and, in this way, stem the advance of Alzheimer's disease.
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29
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Nunomura A, Castellani RJ, Lee HG, Moreira PI, Zhu X, Perry G, Smith MA. Neuropathology in Alzheimer's disease: awaking from a hundred-year-old dream. ACTA ACUST UNITED AC 2006; 2006:pe10. [PMID: 16672726 DOI: 10.1126/sageke.2006.8.pe10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
For one hundred years after Alois Alzheimer's first report of Alzheimer's disease (AD) in 1906, the pathological hallmarks of the disease, senile plaques and neurofibrillary tangles (NFTs), have been attractive targets for researchers. Therefore, not surprisingly, efforts to understand disease mechanisms have concentrated on the cell biology of amyloid-beta (Abeta) deposition as senile plaques or on the phosphorylation and aggregation of tau as NFTs. However, it now appears that this focus on pathology as a central contributor to disease may be misguided. Indeed, neurons associated with Abeta and NFTs in AD brain show a decrease in oxidative damage relative to those in vulnerable but morphologically intact areas of the brain, suggesting that neurodegenerative lesions are compensatory phenomena, and thus manifestations of cellular adaptation. That Abeta and tau accumulations indicate an age-related physiological reaction to chronic stress calls into question the rationale of current therapeutic efforts targeted toward lesion removal. Moreover, if this concept holds true for pathology in other neurodegenerative diseases, we may need to restructure our thinking and undergo a paradigm shift before substantial progress can be made in therapeutic intervention.
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Affiliation(s)
- Akihiko Nunomura
- Department of Psychiatry and Neurology, Asahikawa Medical College, Asahikawa 078-8510, Japan.
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30
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Luo Q, Ding Y, Watson K, Zhang J, Fan GH. N-Methyl-d-aspartate Attenuates CXCR2-Mediated Neuroprotection through Enhancing the Receptor Phosphorylation and Blocking the Receptor Recycling. Mol Pharmacol 2005; 68:528-37. [PMID: 15914698 DOI: 10.1124/mol.105.011197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Abnormal extracellular accumulations of beta-amyloid, a major component of the senile plaques, and of the excitatory amino acid glutamate are both believed to be associated with degeneration of nerve cells in the central nervous system of patients with Alzheimer's disease. The chemokine receptor CXCR2 has been shown to play a role in protecting neurons against beta-amyloid-induced injury in vitro, but it remains unclear whether CXCR2-mediated neuroprotection is affected by glutamate. We demonstrated that pretreatment of hippocampal neurons with a sublethal concentration of N-methyl-d-aspartate (NMDA) attenuated the macrophage inflammatory protein 2 (MIP2)-induced protection against beta-amyloid-induced neuronal death. The NMDA induced inhibition was blocked by (+)-5-methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801), a noncompetitive NMDA receptor antagonist, indicating the involvement of NMDA receptors in this process. A sublethal dose of NMDA pretreatment induced CXCR2 phosphorylation, although to a lesser extent than the receptor phosphorylation induced by MIP2, and differential serine residues were involved in NMDA- and MIP2-induced CXCR2 phosphorylation. Moreover, NMDA treatment reduced the CXCR2-mediated Ca(2+) mobilization, suggesting that NMDA induces cross-desensitization of CXCR2. CXCR2 underwent dephosphorylation after removal of the extracellular ligand, but the dephosphorylation rate was significantly reduced in the cells pretreated with NMDA. Treatment of the neuronal cells with NMDA retarded the recycling of CXCR2. In view of the critical role of receptor phosphorylation and recycling in the functional responsiveness of the chemokine receptor, these observations indicate a novel pathway through which glutamate may interfere with the neuroprotective function of chemokines.
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Affiliation(s)
- Qingwei Luo
- Department of Pharmacology, Meharry Medical College, 1005 Dr. D. B Todd Jr Blvd, Nashville, TN 37208, USA
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31
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Bishop GM, Robinson SR. The amyloid paradox: amyloid-beta-metal complexes can be neurotoxic and neuroprotective. Brain Pathol 2005; 14:448-52. [PMID: 15605992 PMCID: PMC8095825 DOI: 10.1111/j.1750-3639.2004.tb00089.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Senile plaques in the brains of people with Alzheimer disease (AD) are primarily composed of the amyloid-beta (Abeta) peptide and contain substantially elevated levels of iron, copper and zinc. These metals bind to Abeta and have been reported to increase the toxicity of Abeta to cultured neurones. Other reports have demonstrated that Abeta can reduce the neurotoxicity of metal ions, suggesting that the interaction can, under some circumstances, be protective. To investigate these apparently conflicting results, human Abeta1-42 was co-injected with iron, copper or zinc (at the concentrations found in plaques) into rat cerebral cortex, and the resulting numbers of dying neurones were compared. It was found that Abeta complexed with either iron or zinc was more toxic than Abeta alone. In contrast, Abeta-copper complexes were not neurotoxic. Surprisingly, we observed that when iron or copper were combined with Abeta, the neurotoxicity of these metals was substantially reduced, suggesting that Abeta may help to limit the toxicity of redox-active metal ions, thereby assisting the antioxidant defence of the brain. Thus paradoxical effects occur when Abeta complexes with metal ions, where Abeta-metal complexes are capable of being neurotoxic and neuroprotective.
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Affiliation(s)
- Glenda M Bishop
- School of Psychology, Psychiatry and Psychological Medicine, Monash University, Australia.
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32
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Schenck JF, Zimmerman EA. High-field magnetic resonance imaging of brain iron: birth of a biomarker? NMR IN BIOMEDICINE 2004; 17:433-445. [PMID: 15523705 DOI: 10.1002/nbm.922] [Citation(s) in RCA: 246] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The brain has an unusually high concentration of iron, which is distributed in an unusual pattern unlike that in any other organ. The physiological role of this iron and the reasons for this pattern of distribution are not yet understood. There is increasing evidence that several neurodegenerative diseases are associated with altered brain iron metabolism. Understanding these dysmetabolic conditions may provide important information for their diagnosis and treatment. For many years the iron distribution in the human brain could be studied effectively only under postmortem conditions. This situation was changed dramatically by the finding that T2-weighted MR imaging at high field strength (initially 1.5 T) appears to demonstrate the pattern of iron distribution in normal brains and that this imaging technique can detect changes in brain iron concentrations associated with disease states. Up to the present time this imaging capability has been utilized in many research applications but it has not yet been widely applied in the routine diagnosis and management of neurodegenerative disorders. However, recent advances in the basic science of brain iron metabolism, the clinical understanding of neurodegenerative diseases and in MRI technology, particularly in the availability of clinical scanners operating at the higher field strength of 3 T, suggest that iron-dependent MR imaging may soon provide biomarkers capable of characterizing the presence and progression of important neurological disorders. Such biomarkers may be of crucial assistance in the development and utilization of effective new therapies for Alzheimer's and Parkinson's diseases, multiple sclerosis and other iron-related CNS disorders which are difficult to diagnose and treat.
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Affiliation(s)
- John F Schenck
- General Electric Global Research Center, Schenectady, New York 12309, USA.
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Bishop GM, Robinson SR. Physiological Roles of Amyloid-?? and Implications for its Removal in Alzheimer???s Disease. Drugs Aging 2004; 21:621-30. [PMID: 15287821 DOI: 10.2165/00002512-200421100-00001] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The underlying pathological cause of Alzheimer's disease has been postulated to be an excess of amyloid-beta (Abeta) which aggregates into toxic fibrillar deposits within the extracellular space of the brain, thereby disrupting neuronal and synaptic function and eventually leading to neuronal degeneration and dementia. As a result, therapeutic strategies have been developed that are designed to remove Abeta from the brain. Caution needs to be exercised concerning such strategies because, in addition to its presence in neuritic plaques, Abeta has a widespread distribution through the brain and body, even in cognitively normal individuals. Evidence indicates that instead of being a toxic peptide, soluble Abeta serves a variety of physiological functions, including modulation of synaptic function, facilitation of neuronal growth and survival, protection against oxidative stress, and surveillance against neuroactive compounds, toxins and pathogens. These physiological functions must be taken into account when strategies are developed to reduce Abeta load in Alzheimer's disease. Ideally, such strategies should target forms of Abeta that are not bioavailable, such as fibrillar Abeta, or forms that are regarded to be overexpressed in Alzheimer's disease (such as oligomers) while leaving normal soluble Abeta1-40 and Abeta1-42 intact. At present none of the available therapeutic strategies appears to have such selectivity. Until these technical limitations and the uncertainties regarding the effect of depletion of Abeta from the brain are resolved, it would not be prudent to begin further clinical trials.
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Affiliation(s)
- Glenda M Bishop
- School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton, Victoria, Australia
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