51
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Rasmussen PM, Aamand R, Weitzberg E, Christiansen M, Østergaard L, Lund TE. APOE gene-dependent BOLD responses to a breath-hold across the adult lifespan. NEUROIMAGE-CLINICAL 2019; 24:101955. [PMID: 31408838 PMCID: PMC6699560 DOI: 10.1016/j.nicl.2019.101955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/21/2019] [Accepted: 07/19/2019] [Indexed: 11/03/2022]
Abstract
Age and apolipoprotein E (APOE) e4 genotype are two of the strongest known risk factors for sporadic Alzheimer's disease (AD). Neuroimaging has shown hemodynamic response changes with age, in asymptomatic carriers of the APOE e4 allele, and in AD. In this study, we aimed to characterize and differentiate age- and APOE gene-specific hemodynamic changes to breath-hold and visual stimulation. A further aim was to study whether these responses were modulated by 3-day intake of nitrate, a nitric oxide (NO) source. The study was designed as a randomized, double-blinded, placebo-controlled crossover study, and the study cohort comprised 41 APOE e4 carriers (e3/e4 or e4/e4 genotype) and 40 non-carriers (e3/e3 genotype) aged 30-70 years at enrollment. The participants underwent two scanning sessions, each preceded by ingestion of sodium nitrate or sodium chloride (control). During functional magnetic resonance imaging (fMRI) sessions, participants performed two concurrent tasks; a breath-hold task to probe cerebrovascular reactivity and a visual stimulation task to evoke functional hyperemia, respectively. We found that the blood oxygenation level dependent (BOLD) hemodynamic response to breath-hold was altered in APOE e4 carriers relative to non-carriers. Mid-aged (50-60 years of age) e4 carriers exhibited a significantly increased peak time relative to mid-aged e3 carriers, and peak time for younger (30-40 years of age) e4 carriers was significantly shorter than that of mid-aged e4 carriers. The response width was significantly increased for e4 carriers. The response peak magnitude significantly decreased with age. For the visual stimulation task, we found age-related changes, with reduced response magnitude with age but no significant effect of APOE allele type. We found no effect of nitrate ingestion on BOLD responses evoked by the breath-hold and visual stimulation tasks. The APOE gene-dependent response to breath-hold may reflect NO-independent differences in vascular function.
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Affiliation(s)
- Peter M Rasmussen
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
| | - Rasmus Aamand
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Eddie Weitzberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Michael Christiansen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Torben E Lund
- Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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52
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Frösen J, Joutel A. Smooth muscle cells of intracranial vessels: from development to disease. Cardiovasc Res 2019; 114:501-512. [PMID: 29351598 DOI: 10.1093/cvr/cvy002] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Accepted: 01/12/2018] [Indexed: 02/02/2023] Open
Abstract
Cerebrovascular diseases that cause ischaemic or haemorrhagic stroke with subsequent loss of life or functional capacity due to damage of the brain tissue are among the leading causes of human suffering and economic burden inflicted by diseases in the developed world. Diseases affecting intracranial vessels are significant contributors to ischaemic and haemorrhagic strokes. Brain arteriovenous malformations, which are a collection of abnormal blood vessels connecting arteries to veins, are the most common cause of intracranial haemorrhage in children and young adults. Saccular intracranial aneurysms, which are pathological saccular dilations mainly occurring at bifurcations of the large intracranial arteries near the circle of Willis, are highly prevalent in the middle-aged population, causing significant anxiety and concern; their rupture, although rare, is a significant cause of intracranial haemorrhage in those past middle age that is associated with a very sinister prognosis. Cerebral small-vessel disease, which comprise all pathological processes affecting vessels <500 microns in diameter, account for the majority of intracerebral haemorrhages and ∼25% of ischaemic strokes and 45% of dementias in the elderly. In this review, we summarize the developmental, structural, and functional features of intracranial vessels. We then describe the role of smooth muscle cells in brain arteriovenous malformations, intracranial aneurysms, and small-vessel diseases, and discuss how the peculiar ontogeny, structure, and function of intracranial vessels are related to the development of these diseases.
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Affiliation(s)
- Juhana Frösen
- Hemorrhagic Brain Pathology Research Group, NeuroCenter, Kuopio University Hospital, Kuopio 70029, Finland.,Department of Neurosurgery, Kuopio University Hospital, Kuopio 70029, Finland
| | - Anne Joutel
- Genetics and Pathogenesis of Cerebrovascular Diseases, INSERM, Université Paris Diderot-Paris 7, 10 av de Verdun, Paris 75010, France.,DHU NeuroVasc, Sorbonne Paris Cité, Paris 75010, France
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53
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Hachinski V, Einhäupl K, Ganten D, Alladi S, Brayne C, Stephan BCM, Sweeney MD, Zlokovic B, Iturria-Medina Y, Iadecola C, Nishimura N, Schaffer CB, Whitehead SN, Black SE, Østergaard L, Wardlaw J, Greenberg S, Friberg L, Norrving B, Rowe B, Joanette Y, Hacke W, Kuller L, Dichgans M, Endres M, Khachaturian ZS. Preventing dementia by preventing stroke: The Berlin Manifesto. Alzheimers Dement 2019; 15:961-984. [PMID: 31327392 PMCID: PMC7001744 DOI: 10.1016/j.jalz.2019.06.001] [Citation(s) in RCA: 185] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The incidence of stroke and dementia are diverging across the world, rising for those in low- and middle-income countries and falling in those in high-income countries. This suggests that whatever factors cause these trends are potentially modifiable. At the population level, neurological disorders as a group account for the largest proportion of disability-adjusted life years globally (10%). Among neurological disorders, stroke (42%) and dementia (10%) dominate. Stroke and dementia confer risks for each other and share some of the same, largely modifiable, risk and protective factors. In principle, 90% of strokes and 35% of dementias have been estimated to be preventable. Because a stroke doubles the chance of developing dementia and stroke is more common than dementia, more than a third of dementias could be prevented by preventing stroke. Developments at the pathological, pathophysiological, and clinical level also point to new directions. Growing understanding of brain pathophysiology has unveiled the reciprocal interaction of cerebrovascular disease and neurodegeneration identifying new therapeutic targets to include protection of the endothelium, the blood-brain barrier, and other components of the neurovascular unit. In addition, targeting amyloid angiopathy aspects of inflammation and genetic manipulation hold new testable promise. In the meantime, accumulating evidence suggests that whole populations experiencing improved education, and lower vascular risk factor profiles (e.g., reduced prevalence of smoking) and vascular disease, including stroke, have better cognitive function and lower dementia rates. At the individual levels, trials have demonstrated that anticoagulation of atrial fibrillation can reduce the risk of dementia by 48% and that systolic blood pressure lower than 140 mmHg may be better for the brain. Based on these considerations, the World Stroke Organization has issued a proclamation, endorsed by all the major international organizations focused on global brain and cardiovascular health, calling for the joint prevention of stroke and dementia. This article summarizes the evidence for translation into action.
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Affiliation(s)
- Vladimir Hachinski
- Department of Clinical Neurological Sciences, Western University, Ontario, Canada.
| | - Karl Einhäupl
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Detlev Ganten
- Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Suvarna Alladi
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India
| | - Carol Brayne
- Department of Public Health and Primary Care in the University of Cambridge, Cambridge, UK
| | - Blossom C M Stephan
- Institute of Mental Health, Division of Psychiatry and Applied Psychology, School of Medicine, University of Nottingham, Nottingham, UK
| | - Melanie D Sweeney
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Berislav Zlokovic
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Yasser Iturria-Medina
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - Costantino Iadecola
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Nozomi Nishimura
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Chris B Schaffer
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Shawn N Whitehead
- Department of Anatomy and Cell Biology, Western University, Ontario, Canada
| | - Sandra E Black
- Department of Medicine (Neurology), Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - Leif Østergaard
- Department of Clinical Medicine, Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark; Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark
| | - Joanna Wardlaw
- Centre for Clinical Brain Sciences, Edinburgh Imaging, UK Dementia Research Institute, University of Edinburgh, Scotland, UK
| | - Steven Greenberg
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Leif Friberg
- Department of Clinical Sciences, Karolinska Institute, Stockholm, Sweden
| | - Bo Norrving
- Department of Clinical Sciences, Neurology, Lund University, Lund, Sweden
| | - Brian Rowe
- Department of Emergency Medicine and School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - Yves Joanette
- Canadian Institute of Health and Research, Ottawa, Canada
| | - Werner Hacke
- Department of Neurology, Heidelberg University, Heidelberg, Germany
| | - Lewis Kuller
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Martin Dichgans
- Institute for Stroke and Dementia Research (ISD), University Hospital, Ludwig-Maximilians-Universität LMU, Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; German Center for Neurodegenerative Diseases (DZNE, Munich), Munich, Germany
| | - Matthias Endres
- Department of Neurology with Experimental Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany; ExcellenceCluster NeuroCure, Charité-Universitätsmedizin Berlin, Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE), partner site Berlin, Berlin, Germany; German Centre for Cardiovascular Research (DZHK), partner site Berlin, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
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54
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Govindpani K, McNamara LG, Smith NR, Vinnakota C, Waldvogel HJ, Faull RL, Kwakowsky A. Vascular Dysfunction in Alzheimer's Disease: A Prelude to the Pathological Process or a Consequence of It? J Clin Med 2019; 8:E651. [PMID: 31083442 PMCID: PMC6571853 DOI: 10.3390/jcm8050651] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/29/2019] [Accepted: 05/06/2019] [Indexed: 12/19/2022] Open
Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia. Despite decades of research following several theoretical and clinical lines, all existing treatments for the disorder are purely symptomatic. AD research has traditionally been focused on neuronal and glial dysfunction. Although there is a wealth of evidence pointing to a significant vascular component in the disease, this angle has been relatively poorly explored. In this review, we consider the various aspects of vascular dysfunction in AD, which has a significant impact on brain metabolism and homeostasis and the clearance of β-amyloid and other toxic metabolites. This may potentially precede the onset of the hallmark pathophysiological and cognitive symptoms of the disease. Pathological changes in vessel haemodynamics, angiogenesis, vascular cell function, vascular coverage, blood-brain barrier permeability and immune cell migration may be related to amyloid toxicity, oxidative stress and apolipoprotein E (APOE) genotype. These vascular deficits may in turn contribute to parenchymal amyloid deposition, neurotoxicity, glial activation and metabolic dysfunction in multiple cell types. A vicious feedback cycle ensues, with progressively worsening neuronal and vascular pathology through the course of the disease. Thus, a better appreciation for the importance of vascular dysfunction in AD may open new avenues for research and therapy.
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Affiliation(s)
- Karan Govindpani
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Laura G McNamara
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Nicholas R Smith
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Chitra Vinnakota
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Richard Lm Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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55
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Novel Therapeutic Potentials of Taxifolin for Amyloid-β-associated Neurodegenerative Diseases and Other Diseases: Recent Advances and Future Perspectives. Int J Mol Sci 2019; 20:ijms20092139. [PMID: 31052203 PMCID: PMC6539020 DOI: 10.3390/ijms20092139] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 04/17/2019] [Accepted: 04/27/2019] [Indexed: 12/21/2022] Open
Abstract
Amyloid-β (Aβ) has been closely implicated in the pathogenesis of cerebral amyloid angiopathy (CAA) and Alzheimer’s disease (AD), the major causes of dementia. Thus, Aβ could be a target for the treatment of these diseases, for which, currently, there are no established effective treatments. Taxifolin is a bioactive catechol-type flavonoid present in various plants, such as herbs, and it exhibits pleiotropic effects including anti-oxidant and anti-glycation activities. Recently, we have demonstrated that taxifolin inhibits Aβ fibril formation in vitro and have further shown that it improves cerebral blood flow, facilitating Aβ clearance in the brain and suppressing cognitive decline in a mouse model of CAA. These findings suggest the novel therapeutic potentials of taxifolin for CAA. Furthermore, recent extensive studies have reported several novel aspects of taxifolin supporting its potential as a therapeutic drug for AD and metabolic diseases with a high risk for dementia as well as for CAA. In this review, we have summarized the recent advances in taxifolin research based on in vitro, in vivo, and in silico approaches. Furthermore, we have discussed future research directions on the potential of taxifolin for use in novel therapeutic strategies for CAA, AD, and metabolic diseases with an increased risk for dementia.
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56
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Mechanisms Associated with Type 2 Diabetes as a Risk Factor for Alzheimer-Related Pathology. Mol Neurobiol 2019; 56:5815-5834. [PMID: 30684218 DOI: 10.1007/s12035-019-1475-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/10/2019] [Indexed: 12/19/2022]
Abstract
Current evidence suggests dementia and pathology in Alzheimer's Disease (AD) are both dependent and independent of amyloid processing and can be induced by multiple 'hits' on vital neuronal functions. Type 2 diabetes (T2D) poses the most important risk factor for developing AD after ageing and dysfunctional IR/PI3K/Akt signalling is a major contributor in both diseases. We developed a model of T2D, coupling subdiabetogenic doses of streptozotocin (STZ) with a human junk food (HJF) diet to more closely mimic the human condition. Over 35 weeks, this induced classic signs of T2D (hyperglycemia and insulin dysfunction) and a modest, but stable deficit in spatial recognition memory, with very little long-term modification of proteins in or associated with IR/PI3K/Akt signalling in CA1 of the hippocampus. Intracerebroventricular infusion of soluble amyloid beta 42 (Aβ42) to mimic the early preclinical rise in Aβ alone induced a more severe, but short-lasting deficits in memory and deregulation of proteins. Infusion of Aβ on the T2D phenotype exacerbated and prolonged the memory deficits over approximately 4 months, and induced more severe aberrant regulation of proteins associated with autophagy, inflammation and glucose uptake from the periphery. A mild form of environmental enrichment transiently rescued memory deficits and could reverse the regulation of some, but not all protein changes. Together, these data identify mechanisms by which T2D could create a modest dysfunctional neuronal milieu via multiple and parallel inputs that permits the development of pathological events identified in AD and memory deficits when Aβ levels are transiently effective in the brain.
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57
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Lazic D, Sagare AP, Nikolakopoulou AM, Griffin JH, Vassar R, Zlokovic BV. 3K3A-activated protein C blocks amyloidogenic BACE1 pathway and improves functional outcome in mice. J Exp Med 2019; 216:279-293. [PMID: 30647119 PMCID: PMC6363429 DOI: 10.1084/jem.20181035] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/05/2018] [Accepted: 10/30/2018] [Indexed: 12/29/2022] Open
Abstract
3K3A-activated protein C (APC), a cell-signaling analogue of endogenous blood serine protease APC, exerts vasculoprotective, neuroprotective, and anti-inflammatory activities in rodent models of stroke, brain injury, and neurodegenerative disorders. 3K3A-APC is currently in development as a neuroprotectant in patients with ischemic stroke. Here, we report that 3K3A-APC inhibits BACE1 amyloidogenic pathway in a mouse model of Alzheimer's disease (AD). We show that a 4-mo daily treatment of 3-mo-old 5XFAD mice with murine recombinant 3K3A-APC (100 µg/kg/d i.p.) prevents development of parenchymal and cerebrovascular amyloid-β (Aβ) deposits by 40-50%, which is mediated through NFκB-dependent transcriptional inhibition of BACE1, resulting in blockade of Aβ generation in neurons overexpressing human Aβ-precursor protein. Consistent with reduced Aβ deposition, 3K3A-APC normalized hippocampus-dependent behavioral deficits and cerebral blood flow responses, improved cerebrovascular integrity, and diminished neuroinflammatory responses. Our data suggest that 3K3A-APC holds potential as an effective anti-Aβ prevention therapy for early-stage AD.
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Affiliation(s)
- Divna Lazic
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.,Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA.,Department of Neurobiology, Institute for Biological Research, University of Belgrade, Belgrade, Republic of Serbia
| | - Abhay P Sagare
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.,Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Angeliki M Nikolakopoulou
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.,Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - John H Griffin
- The Scripps Research Institute, La Jolla, CA.,Department of Medicine, University of California, San Diego, San Diego, CA
| | - Robert Vassar
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | - Berislav V Zlokovic
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA .,Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA
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58
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Leira Y, Rodríguez‐Yáñez M, Arias S, López‐Dequidt I, Campos F, Sobrino T, D'Aiuto F, Castillo J, Blanco J. Periodontitis is associated with systemic inflammation and vascular endothelial dysfunction in patients with lacunar infarct. J Periodontol 2018; 90:465-474. [DOI: 10.1002/jper.18-0560] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/21/2018] [Accepted: 10/23/2018] [Indexed: 01/30/2023]
Affiliation(s)
- Yago Leira
- Periodontology UnitFaculty of Medicine and OdontologyUniversity of Santiago de CompostelaMedical‐Surgical Dentistry (OMEQUI) Research GroupHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
- Periodontology UnitUCL Eastman Dental Institute and HospitalUniversity College London London UK
| | - Manuel Rodríguez‐Yáñez
- Clinical Neurosciences Research LaboratoryDepartment of NeurologyClinical University HospitalHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
| | - Susana Arias
- Clinical Neurosciences Research LaboratoryDepartment of NeurologyClinical University HospitalHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
| | - Iria López‐Dequidt
- Clinical Neurosciences Research LaboratoryDepartment of NeurologyClinical University HospitalHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
| | - Francisco Campos
- Clinical Neurosciences Research LaboratoryDepartment of NeurologyClinical University HospitalHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
| | - Tomás Sobrino
- Clinical Neurosciences Research LaboratoryDepartment of NeurologyClinical University HospitalHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
| | - Francesco D'Aiuto
- Periodontology UnitUCL Eastman Dental Institute and HospitalUniversity College London London UK
| | - José Castillo
- Clinical Neurosciences Research LaboratoryDepartment of NeurologyClinical University HospitalHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
| | - Juan Blanco
- Periodontology UnitFaculty of Medicine and OdontologyUniversity of Santiago de CompostelaMedical‐Surgical Dentistry (OMEQUI) Research GroupHealth Research Institute of Santiago de Compostela (IDIS) Santiago de Compostela Spain
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59
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Tayler HM, Palmer JC, Thomas TL, Kehoe PG, Paton JF, Love S. Cerebral Aβ 40 and systemic hypertension. J Cereb Blood Flow Metab 2018; 38:1993-2005. [PMID: 28782443 PMCID: PMC6259324 DOI: 10.1177/0271678x17724930] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mid-life hypertension and cerebral hypoperfusion may be preclinical abnormalities in people who later develop Alzheimer's disease. Although accumulation of amyloid-beta (Aβ) is characteristic of Alzheimer's disease and is associated with upregulation of the vasoconstrictor peptide endothelin-1 within the brain, it is unclear how this affects systemic arterial pressure. We have investigated whether infusion of Aβ40 into ventricular cerebrospinal fluid modulates blood pressure in the Dahl salt-sensitive rat. The Dahl salt-sensitive rat develops hypertension if given a high-salt diet. Intracerebroventricular infusion of Aβ induced a progressive rise in blood pressure in rats with pre-existing hypertension produced by a high-salt diet ( p < 0.0001), but no change in blood pressure in normotensive rats. The elevation in arterial pressure in high-salt rats was associated with an increase in low frequency spectral density in systolic blood pressure, suggesting autonomic imbalance, and reduced cardiac baroreflex gain. Our results demonstrate the potential for intracerebral Aβ to exacerbate hypertension, through modulation of autonomic activity. Present findings raise the possibility that mid-life hypertension in people who subsequently develop Alzheimer's disease may in some cases be a physiological response to reduced cerebral perfusion complicating the accumulation of Aβ within the brain.
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Affiliation(s)
- Hannah M Tayler
- 1 School of Clinical Sciences, University of Bristol, Bristol, UK
| | | | - Taya L Thomas
- 1 School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Patrick G Kehoe
- 1 School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Julian Fr Paton
- 2 School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK
| | - Seth Love
- 1 School of Clinical Sciences, University of Bristol, Bristol, UK
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60
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Cheng J, Korte N, Nortley R, Sethi H, Tang Y, Attwell D. Targeting pericytes for therapeutic approaches to neurological disorders. Acta Neuropathol 2018; 136:507-523. [PMID: 30097696 PMCID: PMC6132947 DOI: 10.1007/s00401-018-1893-0] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/30/2018] [Accepted: 07/31/2018] [Indexed: 12/13/2022]
Abstract
Many central nervous system diseases currently lack effective treatment and are often associated with defects in microvascular function, including a failure to match the energy supplied by the blood to the energy used on neuronal computation, or a breakdown of the blood–brain barrier. Pericytes, an under-studied cell type located on capillaries, are of crucial importance in regulating diverse microvascular functions, such as angiogenesis, the blood–brain barrier, capillary blood flow and the movement of immune cells into the brain. They also form part of the “glial” scar isolating damaged parts of the CNS, and may have stem cell-like properties. Recent studies have suggested that pericytes play a crucial role in neurological diseases, and are thus a therapeutic target in disorders as diverse as stroke, traumatic brain injury, migraine, epilepsy, spinal cord injury, diabetes, Huntington’s disease, Alzheimer’s disease, diabetes, multiple sclerosis, glioma, radiation necrosis and amyotrophic lateral sclerosis. Here we report recent advances in our understanding of pericyte biology and discuss how pericytes could be targeted to develop novel therapeutic approaches to neurological disorders, by increasing blood flow, preserving blood–brain barrier function, regulating immune cell entry to the CNS, and modulating formation of blood vessels in, and the glial scar around, damaged regions.
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Affiliation(s)
- Jinping Cheng
- Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, 107 Yan Jiang Xi Rd, Guangzhou, 510120, People's Republic of China
| | - Nils Korte
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ross Nortley
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Huma Sethi
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Yamei Tang
- Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, 107 Yan Jiang Xi Rd, Guangzhou, 510120, People's Republic of China.
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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61
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Sweeney MD, Kisler K, Montagne A, Toga AW, Zlokovic BV. The role of brain vasculature in neurodegenerative disorders. Nat Neurosci 2018; 21:1318-1331. [PMID: 30250261 PMCID: PMC6198802 DOI: 10.1038/s41593-018-0234-x] [Citation(s) in RCA: 542] [Impact Index Per Article: 90.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 07/20/2018] [Indexed: 12/12/2022]
Abstract
Adequate supply of blood and structural and functional integrity of blood vessels are key to normal brain functioning. On the other hand, cerebral blood flow shortfalls and blood-brain barrier dysfunction are early findings in neurodegenerative disorders in humans and animal models. Here we first examine molecular definition of cerebral blood vessels, as well as pathways regulating cerebral blood flow and blood-brain barrier integrity. Then we examine the role of cerebral blood flow and blood-brain barrier in the pathogenesis of Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. We focus on Alzheimer's disease as a platform of our analysis because more is known about neurovascular dysfunction in this disease than in other neurodegenerative disorders. Finally, we propose a hypothetical model of Alzheimer's disease biomarkers to include brain vasculature as a factor contributing to the disease onset and progression, and we suggest a common pathway linking brain vascular contributions to neurodegeneration in multiple neurodegenerative disorders.
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Affiliation(s)
- Melanie D Sweeney
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Kassandra Kisler
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Axel Montagne
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Arthur W Toga
- Laboratory of Neuro Imaging, Stevens Institute for Neuroimaging and Informatics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Berislav V Zlokovic
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
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Jian WX, Zhang Z, Chu SF, Peng Y, Chen NH. Potential roles of brain barrier dysfunctions in the early stage of Alzheimer’s disease. Brain Res Bull 2018; 142:360-367. [DOI: 10.1016/j.brainresbull.2018.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/03/2018] [Accepted: 08/17/2018] [Indexed: 02/07/2023]
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Kelly P, Hudry E, Hou SS, Bacskai BJ. In Vivo Two Photon Imaging of Astrocytic Structure and Function in Alzheimer's Disease. Front Aging Neurosci 2018; 10:219. [PMID: 30072889 PMCID: PMC6060286 DOI: 10.3389/fnagi.2018.00219] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 06/26/2018] [Indexed: 12/17/2022] Open
Abstract
The physiological function of the neurovascular unit is critically dependent upon the complex structure and functions of astrocytes for optimal preservation of cerebral homeostasis. While it has been shown that astrocytes exhibit aberrant changes in both structure and function in transgenic murine models of Alzheimer’s disease (AD), it is not fully understood how this altered phenotype contributes to the pathogenesis of AD or whether this alteration predicts a therapeutic target in AD. The mechanisms underlying the spatiotemporal relationship between astrocytes, neurons and the vasculature in their orchestrated regulation of local cerebral flow in active brain regions has not been fully elucidated in brain physiology and in AD. As there is an incredible urgency to identify therapeutic targets that are well-tolerated and efficacious in protecting the brain against the pathological impact of AD, here we use the current body of literature to evaluate the hypothesis that pathological changes in astrocytes are central to the pathogenesis of AD. We also examine the current tools available to assess astrocytic calcium signaling in the living murine brain as it has an important role in the complex interaction between astrocytes, neurons and the vasculature. Furthermore, we discuss the altered function of astrocytes in their interaction with neurons in the preservation of glutamate homeostasis and additionally address the role of astrocytes at the vascular interface and their contribution to functional hyperemia within the living murine brain in health and in AD.
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Affiliation(s)
- Patricia Kelly
- Massachusetts Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Harvard University, Boston, MA, United States
| | - Eloise Hudry
- Massachusetts Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Harvard University, Boston, MA, United States
| | - Steven S Hou
- Massachusetts Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Harvard University, Boston, MA, United States
| | - Brian J Bacskai
- Massachusetts Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Harvard University, Boston, MA, United States
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64
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Kisler K, Lazic D, Sweeney MD, Plunkett S, Khatib ME, Vinogradov SA, Boas DA, Sakadžić S, Zlokovic BV. In vivo imaging and analysis of cerebrovascular hemodynamic responses and tissue oxygenation in the mouse brain. Nat Protoc 2018; 13:1377-1402. [PMID: 29844521 PMCID: PMC6402338 DOI: 10.1038/nprot.2018.034] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cerebrovascular dysfunction has an important role in the pathogenesis of multiple brain disorders. Measurement of hemodynamic responses in vivo can be challenging, particularly as techniques are often not described in sufficient detail and vary between laboratories. We present a set of standardized in vivo protocols that describe high-resolution two-photon microscopy and intrinsic optical signal (IOS) imaging to evaluate capillary and arteriolar responses to a stimulus, regional hemodynamic responses, and oxygen delivery to the brain. The protocol also describes how to measure intrinsic NADH fluorescence to understand how blood O2 supply meets the metabolic demands of activated brain tissue, and to perform resting-state absolute oxygen partial pressure (pO2) measurements of brain tissue. These methods can detect cerebrovascular changes at far higher resolution than MRI techniques, although the optical nature of these techniques limits their achievable imaging depths. Each individual procedure requires 1-2 h to complete, with two to three procedures typically performed per animal at a time. These protocols are broadly applicable in studies of cerebrovascular function in healthy and diseased brain in any of the existing mouse models of neurological and vascular disorders. All these procedures can be accomplished by a competent graduate student or experienced technician, except the two-photon measurement of absolute pO2 level, which is better suited to a more experienced, postdoctoral-level researcher.
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Affiliation(s)
- Kassandra Kisler
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089
| | - Divna Lazic
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089
- Department of Neurobiology, Institute for Biological Research, University of Belgrade, Belgrade, Republic of Serbia
| | - Melanie D. Sweeney
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089
| | - Shane Plunkett
- Departments of Biochemistry and Biophysics and of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Mirna El Khatib
- Departments of Biochemistry and Biophysics and of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Sergei A. Vinogradov
- Departments of Biochemistry and Biophysics and of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - David A. Boas
- Optics Division, MGH/HMS/MIT Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, MA 02129
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215
| | - Sava Sakadžić
- Optics Division, MGH/HMS/MIT Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, MA 02129
| | - Berislav V. Zlokovic
- Department of Physiology and Neuroscience and the Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089
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65
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Hecht M, Krämer LM, von Arnim CAF, Otto M, Thal DR. Capillary cerebral amyloid angiopathy in Alzheimer's disease: association with allocortical/hippocampal microinfarcts and cognitive decline. Acta Neuropathol 2018; 135:681-694. [PMID: 29574591 DOI: 10.1007/s00401-018-1834-y] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 01/03/2023]
Abstract
Cerebral amyloid angiopathy (CAA) is caused by the deposition of the amyloid β-protein (Aβ) in the wall of cerebral and leptomeningeal blood vessels and is related to Alzheimer's disease (AD). Capillary Aβ deposition is observed in a subset of CAA cases and represents a distinct type of CAA named capillary CAA or CAA type 1. This type of CAA is strongly associated with the presence of the apolipoprotein E ε4 allele. CAA type 1-associated AD cases often exhibit a more severe Aβ plaque pathology but less widespread neurofibrillary tangle (NFT) pathology. The objective of this study was to analyze whether capillary CAA and its effects on cerebral blood flow have an impact on dementia. To address this objective, we performed neuropathological evaluation of 284 autopsy cases of demented and non-demented individuals. We assessed the presence of CAA and its subtypes as well as for that of hemorrhages and infarcts. Capillary CAA and CAA severity were associated with allocortical microinfarcts, comprising the CA1 region of the hippocampus. Allocortical microinfarcts, capillary CAA and CAA severity were, thereby, associated with cognitive decline. In conclusion, allocortical microinfarcts, CAA severity, and the capillary type of CAA were associated with one another and with the development of cognitive decline. Thus, AD cases with CAA type 1 (capillary CAA) appear to develop dementia symptoms not only due to AD-related Aβ plaque and NFT pathology but also due to hippocampal microinfarcts that are associated with CAA type 1 and CAA severity, and that damage a brain region important for memory function.
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Affiliation(s)
- Moritz Hecht
- Laboratory of Neuropathology, Institute of Pathology, University of Ulm, Ulm, Germany
| | - Lara Maria Krämer
- Laboratory of Neuropathology, Institute of Pathology, University of Ulm, Ulm, Germany
| | - Christine A F von Arnim
- Department of Neurology, University of Ulm, Ulm, Germany
- Clinic for Neurogeriatrics and neurological Rehabilitation, University- und Rehabilitation Hospital Ulm (RKU), Ulm, Germany
| | - Markus Otto
- Department of Neurology, University of Ulm, Ulm, Germany
| | - Dietmar Rudolf Thal
- Laboratory of Neuropathology, Institute of Pathology, University of Ulm, Ulm, Germany.
- Departement Neurowetenschappen, Katholieke Universiteit Leuven, Herestraat 49, Leuven, Belgium.
- Departement Pathologische Ontleedkunde, UZ Leuven, Leuven, Belgium.
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66
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Nagai M, Dote K, Kato M, Sasaki S, Oda N, Kagawa E, Nakano Y, Yamane A, Higashihara T, Miyauchi S, Tsuchiya A. Visit-to-Visit Blood Pressure Variability and Alzheimer's Disease: Links and Risks. J Alzheimers Dis 2018; 59:515-526. [PMID: 28598842 DOI: 10.3233/jad-161172] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
While hypertension has been shown to be a risk factor for vascular dementia, several studies have also demonstrated that hypertension also increases the risk of Alzheimer's disease (AD). Although the relationship between visit-to-visit blood pressure variability (VVV) and cognitive impairment, including AD, have been provided, the mechanisms remain poorly understood. This review paper focuses on the relationship of VVV with AD and summarizes the pathophysiology underlying that relationship, which appears to be mediated by arterial stiffness.
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Affiliation(s)
- Michiaki Nagai
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Keigo Dote
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Masaya Kato
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Shota Sasaki
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Noboru Oda
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Eisuke Kagawa
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Yoshinori Nakano
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Aya Yamane
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | | | - Shunsuke Miyauchi
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Akane Tsuchiya
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
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67
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Kehoe PG, Blair PS, Howden B, Thomas DL, Malone IB, Horwood J, Clement C, Selman LE, Baber H, Lane A, Coulthard E, Passmore AP, Fox NC, Wilkinson IB, Ben-Shlomo Y. The Rationale and Design of the Reducing Pathology in Alzheimer's Disease through Angiotensin TaRgeting (RADAR) Trial. J Alzheimers Dis 2018; 61:803-814. [PMID: 29226862 DOI: 10.3233/jad-170101] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Anti-hypertensives that modify the renin angiotensin system may reduce Alzheimer's disease (AD) pathology and reduce the rate of disease progression. OBJECTIVE To conduct a phase II, two arm, double-blind, placebo-controlled, randomized trial of losartan to test the efficacy of Reducing pathology in Alzheimer's Disease through Angiotensin TaRgeting (RADAR). METHODS Men and women aged at least 55 years with mild-to-moderate AD will be randomly allocated 100 mg encapsulated generic losartan or placebo once daily for 12 months after successful completion of a 2-week open-label phase and 2-week placebo washout to establish drug tolerability. 228 participants will provide at least 182 subjects with final assessments to provide 84% power to detect a 25% difference in atrophy rate (therapeutic benefit) change over 12 months at an alpha level of 0.05. We will use intention-to-treat analysis, estimating between-group differences in outcomes derived from appropriate (linear or logistic) multivariable regression models adjusting for minimization variables. RESULTS The primary outcome will be rate of whole brain atrophy as a surrogate measure of disease progression. Secondary outcomes will include changes to 1) white matter hyperintensity volume and cerebral blood flow; 2) performance on a standard series of assessments of memory, cognitive function, activities of daily living, and quality of life. Major assessments (for all outcomes) and relevant safety monitoring of blood pressure and bloods will be at baseline and 12 months. Additional cognitive assessment will also be conducted at 6 months along with safety blood pressure and blood monitoring. Monitoring of blood pressure, bloods, and self-reported side effects will occur during the open-label phase and during the majority of the post-randomization dispensing visits. CONCLUSION This study will identify whether losartan is efficacious in the treatment of AD and whether definitive Phase III trials are warranted.
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Affiliation(s)
- Patrick G Kehoe
- Dementia Research Group, Translational Health Sciences, Bristol Medical School, University of Bristol, Faculty of Health Sciences, Level 1 Learning and Research>, Southmead Hospital, Bristol, UK
| | - Peter S Blair
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Beth Howden
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - David L Thomas
- Leonard Wolfson Experimental Neurology Centre, UCL Institute of Neurology, Queen Square, London, UK
- Dementia Research Centre (DRC), Institute of Neurology, University College London, Queen Square, London, UK
| | - Ian B Malone
- Dementia Research Centre (DRC), Institute of Neurology, University College London, Queen Square, London, UK
| | - Jeremy Horwood
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Clare Clement
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Lucy E Selman
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Hannah Baber
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Athene Lane
- Bristol Randomised Trials Collaboration (BRTC), Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Elizabeth Coulthard
- ReMemBr Group, Translational Health Sciences, Bristol Medical School, University of Bristol, Faculty of Health Sciences, Brain Centre, Southmead Hospital, Bristol, UK
| | - Anthony Peter Passmore
- Institute of Clinical Sciences, Queens University Belfast, Royal Victoria Hospital, Belfast, UK
| | - Nick C Fox
- Dementia Research Centre (DRC), Institute of Neurology, University College London, Queen Square, London, UK
| | - Ian B Wilkinson
- Division of Experimental Medicine and Immunotherapeutics, School of Clinical Medicine, University of Cambridge, and Clinical Trials Unit, Addenbrookes Hospital, Cambridge, UK
| | - Yoav Ben-Shlomo
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
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68
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The Neurovascular Unit Coming of Age: A Journey through Neurovascular Coupling in Health and Disease. Neuron 2017; 96:17-42. [PMID: 28957666 DOI: 10.1016/j.neuron.2017.07.030] [Citation(s) in RCA: 1273] [Impact Index Per Article: 181.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 07/20/2017] [Accepted: 07/25/2017] [Indexed: 02/07/2023]
Abstract
The concept of the neurovascular unit (NVU), formalized at the 2001 Stroke Progress Review Group meeting of the National Institute of Neurological Disorders and Stroke, emphasizes the intimate relationship between the brain and its vessels. Since then, the NVU has attracted the interest of the neuroscience community, resulting in considerable advances in the field. Here the current state of knowledge of the NVU will be assessed, focusing on one of its most vital roles: the coupling between neural activity and blood flow. The evidence supports a conceptual shift in the mechanisms of neurovascular coupling, from a unidimensional process involving neuronal-astrocytic signaling to local blood vessels to a multidimensional one in which mediators released from multiple cells engage distinct signaling pathways and effector systems across the entire cerebrovascular network in a highly orchestrated manner. The recently appreciated NVU dysfunction in neurodegenerative diseases, although still poorly understood, supports emerging concepts that maintaining neurovascular health promotes brain health.
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69
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Charidimou A, Boulouis G, Gurol ME, Ayata C, Bacskai BJ, Frosch MP, Viswanathan A, Greenberg SM. Emerging concepts in sporadic cerebral amyloid angiopathy. Brain 2017; 140:1829-1850. [PMID: 28334869 DOI: 10.1093/brain/awx047] [Citation(s) in RCA: 296] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 01/17/2017] [Indexed: 12/27/2022] Open
Abstract
Sporadic cerebral amyloid angiopathy is a common, well-defined small vessel disease and a largely untreatable cause of intracerebral haemorrhage and contributor to age-related cognitive decline. The term 'cerebral amyloid angiopathy' now encompasses not only a specific cerebrovascular pathological finding, but also different clinical syndromes (both acute and progressive), brain parenchymal lesions seen on neuroimaging and a set of diagnostic criteria-the Boston criteria, which have resulted in increasingly detected disease during life. Over the past few years, it has become clear that, at the pathophysiological level, cerebral amyloid angiopathy appears to be in part a protein elimination failure angiopathy and that this dysfunction is a feed-forward process, which potentially leads to worsening vascular amyloid-β accumulation, activation of vascular injury pathways and impaired vascular physiology. From a clinical standpoint, cerebral amyloid angiopathy is characterized by individual focal lesions (microbleeds, cortical superficial siderosis, microinfarcts) and large-scale alterations (white matter hyperintensities, structural connectivity, cortical thickness), both cortical and subcortical. This review provides an interdisciplinary critical outlook on various emerging and changing concepts in the field, illustrating mechanisms associated with amyloid cerebrovascular pathology and neurological dysfunction.
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Affiliation(s)
- Andreas Charidimou
- Hemorrhagic Stroke Research Program, Department of Neurology, Massachusetts General Hospital Stroke Research Center, Harvard Medical School, Boston, MA, USA
| | - Gregoire Boulouis
- Hemorrhagic Stroke Research Program, Department of Neurology, Massachusetts General Hospital Stroke Research Center, Harvard Medical School, Boston, MA, USA
| | - M Edip Gurol
- Hemorrhagic Stroke Research Program, Department of Neurology, Massachusetts General Hospital Stroke Research Center, Harvard Medical School, Boston, MA, USA
| | - Cenk Ayata
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Brian J Bacskai
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 114, 16th St., Charlestown, MA 02129, USA
| | - Matthew P Frosch
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 114, 16th St., Charlestown, MA 02129, USA.,C.S. Kubik Laboratory for Neuropathology, Department of Pathology, Massachusetts General Hospital and Harvard Medical School, 114, 16th St., Charlestown, MA 02129, USA
| | - Anand Viswanathan
- Hemorrhagic Stroke Research Program, Department of Neurology, Massachusetts General Hospital Stroke Research Center, Harvard Medical School, Boston, MA, USA
| | - Steven M Greenberg
- Hemorrhagic Stroke Research Program, Department of Neurology, Massachusetts General Hospital Stroke Research Center, Harvard Medical School, Boston, MA, USA.,Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 114, 16th St., Charlestown, MA 02129, USA
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70
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Kisler K, Nelson AR, Montagne A, Zlokovic BV. Cerebral blood flow regulation and neurovascular dysfunction in Alzheimer disease. Nat Rev Neurosci 2017; 18:419-434. [PMID: 28515434 PMCID: PMC5759779 DOI: 10.1038/nrn.2017.48] [Citation(s) in RCA: 738] [Impact Index Per Article: 105.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cerebral blood flow (CBF) regulation is essential for normal brain function. The mammalian brain has evolved a unique mechanism for CBF control known as neurovascular coupling. This mechanism ensures a rapid increase in the rate of CBF and oxygen delivery to activated brain structures. The neurovascular unit is composed of astrocytes, mural vascular smooth muscle cells and pericytes, and endothelia, and regulates neurovascular coupling. This Review article examines the cellular and molecular mechanisms within the neurovascular unit that contribute to CBF control, and neurovascular dysfunction in neurodegenerative disorders such as Alzheimer disease.
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Affiliation(s)
- Kassandra Kisler
- Zilkha Neurogenetic Institute, 1501 San Pablo Street, Los Angeles, California 90089, USA
| | - Amy R Nelson
- Zilkha Neurogenetic Institute, 1501 San Pablo Street, Los Angeles, California 90089, USA
| | - Axel Montagne
- Zilkha Neurogenetic Institute, 1501 San Pablo Street, Los Angeles, California 90089, USA
| | - Berislav V Zlokovic
- Zilkha Neurogenetic Institute, 1501 San Pablo Street, Los Angeles, California 90089, USA
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71
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Park L, Uekawa K, Garcia-Bonilla L, Koizumi K, Murphy M, Pistik R, Younkin L, Younkin S, Zhou P, Carlson G, Anrather J, Iadecola C. Brain Perivascular Macrophages Initiate the Neurovascular Dysfunction of Alzheimer Aβ Peptides. Circ Res 2017; 121:258-269. [PMID: 28515043 DOI: 10.1161/circresaha.117.311054] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
RATIONALE Increasing evidence indicates that alterations of the cerebral microcirculation may play a role in Alzheimer disease, the leading cause of late-life dementia. The amyloid-β peptide (Aβ), a key pathogenic factor in Alzheimer disease, induces profound alterations in neurovascular regulation through the innate immunity receptor CD36 (cluster of differentiation 36), which, in turn, activates a Nox2-containing NADPH oxidase, leading to cerebrovascular oxidative stress. Brain perivascular macrophages (PVM) located in the perivascular space, a major site of brain Aβ collection and clearance, are juxtaposed to the wall of intracerebral resistance vessels and are a powerful source of reactive oxygen species. OBJECTIVE We tested the hypothesis that PVM are the main source of reactive oxygen species responsible for the cerebrovascular actions of Aβ and that CD36 and Nox2 in PVM are the molecular substrates of the effect. METHODS AND RESULTS Selective depletion of PVM using intracerebroventricular injection of clodronate abrogates the reactive oxygen species production and cerebrovascular dysfunction induced by Aβ applied directly to the cerebral cortex, administered intravascularly, or overproduced in the brain of transgenic mice expressing mutated forms of the amyloid precursor protein (Tg2576 mice). In addition, using bone marrow chimeras, we demonstrate that PVM are the cells expressing CD36 and Nox2 responsible for the dysfunction. Thus, deletion of CD36 or Nox2 from PVM abrogates the deleterious vascular effects of Aβ, whereas wild-type PVM reconstitute the vascular dysfunction in CD36-null mice. CONCLUSIONS The data identify PVM as a previously unrecognized effector of the damaging neurovascular actions of Aβ and unveil a new mechanism by which brain-resident innate immune cells and their receptors may contribute to the pathobiology of Alzheimer disease.
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Affiliation(s)
- Laibaik Park
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.).
| | - Ken Uekawa
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Lidia Garcia-Bonilla
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Kenzo Koizumi
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Michelle Murphy
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Rose Pistik
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Linda Younkin
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Steven Younkin
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Ping Zhou
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - George Carlson
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Josef Anrather
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.)
| | - Costantino Iadecola
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY (L.P., K.U., L.G.B., K.K., M.M., P.Z., J.A., C.I.); McLaughlin Research Institute, Great Falls, MT (R.P., G.C.); and Mayo Clinic Jacksonville, FL (L.Y., S.Y.).
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72
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Acosta C, Anderson HD, Anderson CM. Astrocyte dysfunction in Alzheimer disease. J Neurosci Res 2017; 95:2430-2447. [PMID: 28467650 DOI: 10.1002/jnr.24075] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022]
Abstract
Astrocytes are glial cells that are distributed throughout the central nervous system in an arrangement optimal for chemical and physical interaction with neuronal synapses and brain blood supply vessels. Neurotransmission modulates astrocytic excitability by activating an array of cell surface receptors and transporter proteins, resulting in dynamic changes in intracellular Ca2+ or Na+ . Ionic and electrogenic astrocytic changes, in turn, drive vital cell nonautonomous effects supporting brain function, including regulation of synaptic activity, neuronal metabolism, and regional blood supply. Alzheimer disease (AD) is associated with aberrant oligomeric amyloid β generation, which leads to extensive proliferation of astrocytes with a reactive phenotype and abnormal regulation of these processes. Astrocytic morphology, Ca2+ responses, extracellular K+ removal, glutamate transport, amyloid clearance, and energy metabolism are all affected in AD, resulting in a deleterious set of effects that includes glutamate excitotoxicity, impaired synaptic plasticity, reduced carbon delivery to neurons for oxidative phosphorylation, and dysregulated linkages between neuronal energy demand and regional blood supply. This review summarizes how astrocytes are affected in AD and describes how these changes are likely to influence brain function. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Crystal Acosta
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada
| | - Hope D Anderson
- Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada.,College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Christopher M Anderson
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba, Canada
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73
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Ogoh S. Relationship between cognitive function and regulation of cerebral blood flow. J Physiol Sci 2017; 67:345-351. [PMID: 28155036 PMCID: PMC10717011 DOI: 10.1007/s12576-017-0525-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 01/23/2017] [Indexed: 12/11/2022]
Abstract
Ageing is the primary risk factor for cognitive deterioration. Given that the cerebral blood flow (CBF) or regulation of cerebral circulation is attenuated in the elderly, it could be expected that ageing-induced cognitive deterioration may be affected by a decrease in CBF as a result of brain ischemia and energy depletion. CBF regulation associated with cerebral metabolism thus likely plays an important role in the preservation of cognitive function. However, in some specific conditions (e.g. during exercise), change in CBF does not synchronize with that of cerebral metabolism. Our recent study demonstrated that cognitive function was more strongly affected by changes in cerebral metabolism than by changes in CBF during exercise. Therefore, it remains unclear how an alteration in CBF or its regulation affects cognitive function. In this review, I summarize current knowledge on previous investigations providing the possibility of an interaction between regulation of CBF or cerebral metabolism and cognitive function.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-Shi, Saitama, 350-8585, Japan.
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74
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Saito S, Yamamoto Y, Maki T, Hattori Y, Ito H, Mizuno K, Harada-Shiba M, Kalaria RN, Fukushima M, Takahashi R, Ihara M. Taxifolin inhibits amyloid-β oligomer formation and fully restores vascular integrity and memory in cerebral amyloid angiopathy. Acta Neuropathol Commun 2017; 5:26. [PMID: 28376923 PMCID: PMC5379578 DOI: 10.1186/s40478-017-0429-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/22/2017] [Indexed: 01/31/2023] Open
Abstract
Cerebral amyloid angiopathy (CAA) induces various forms of cerebral infarcts and hemorrhages from vascular amyloid-β accumulation, resulting in acceleration of cognitive impairment, which is currently untreatable. Soluble amyloid-β protein likely impairs cerebrovascular integrity as well as cognitive function in early stage Alzheimer’s disease. Taxifolin, a flavonol with strong anti-oxidative and anti-glycation activities, has been reported to disassemble amyloid-β in vitro but the in vivo relevance remains unknown. Here, we investigated whether taxifolin has therapeutic potential in attenuating CAA, hypothesizing that inhibiting amyloid-β assembly may facilitate its clearance through several elimination pathways. Vehicle- or taxifolin-treated Tg-SwDI mice (commonly used to model CAA) were used in this investigation. Cognitive and cerebrovascular function, as well as the solubility and oligomerization of brain amyloid-β proteins, were investigated. Spatial reference memory was assessed by water maze test. Cerebral blood flow was measured with laser speckle flowmetry and cerebrovascular reactivity evaluated by monitoring cerebral blood flow changes in response to hypercapnia. Significantly reduced cerebrovascular pan-amyloid-β and amyloid-β1-40 accumulation was found in taxifolin-treated Tg-SwDI mice compared to vehicle-treated counterparts (n = 5). Spatial reference memory was severely impaired in vehicle-treated Tg-SwDI mice but normalized after taxifolin treatment, with scoring similar to wild type mice (n = 10–17). Furthermore, taxifolin completely restored decreased cerebral blood flow and cerebrovascular reactivity in Tg-SwDI mice (n = 4–6). An in vitro thioflavin-T assay showed taxifolin treatment resulted in efficient inhibition of amyloid-β1-40 assembly. In addition, a filter trap assay and ELISA showed Tg-SwDI mouse brain homogenates exhibited significantly reduced levels of amyloid-β oligomers in vivo after taxifolin treatment (n = 4–5), suggesting the effects of taxifolin on CAA are attributable to the inhibition of amyloid-β oligomer formation. In conclusion, taxifolin prevents amyloid-β oligomer assembly and fully sustains cognitive and cerebrovascular function in a CAA model mice. Taxifolin thus appears a promising therapeutic approach for CAA.
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75
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Badhwar A, Brown R, Stanimirovic DB, Haqqani AS, Hamel E. Proteomic differences in brain vessels of Alzheimer's disease mice: Normalization by PPARγ agonist pioglitazone. J Cereb Blood Flow Metab 2017; 37:1120-1136. [PMID: 27339263 PMCID: PMC5363486 DOI: 10.1177/0271678x16655172] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cerebrovascular insufficiency appears years prior to clinical symptoms in Alzheimer's disease. The soluble, highly toxic amyloid-β species, generated from the amyloidogenic processing of amyloid precursor protein, are known instigators of the chronic cerebrovascular insufficiency observed in both Alzheimer's disease patients and transgenic mouse models. We have previously demonstrated that pioglitazone potently reverses cerebrovascular impairments in a mouse model of Alzheimer's disease overexpressing amyloid-β. In this study, we sought to characterize the effects of amyloid-β overproduction on the cerebrovascular proteome; determine how pioglitazone treatment affected the altered proteome; and analyze the relationship between normalized protein levels and recovery of cerebrovascular function. Three-month-old wildtype and amyloid precursor protein mice were treated with pioglitazone- (20 mg/kg/day, 14 weeks) or control-diet. Cerebral arteries were surgically isolated, and extracted proteins analyzed by gel-free and gel-based mass spectrometry. 193 cerebrovascular proteins were abnormally expressed in amyloid precursor protein mice. Pioglitazone treatment rescued a third of these proteins, mainly those associated with oxidative stress, promotion of cerebrovascular vasocontractile tone, and vascular compliance. Our results demonstrate that amyloid-β overproduction perturbs the cerebrovascular proteome. Recovery of cerebrovascular function with pioglitazone is associated with normalized levels of key proteins in brain vessel function, suggesting that pioglitazone-responsive cerebrovascular proteins could be early biomarkers of Alzheimer's disease.
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Affiliation(s)
- AmanPreet Badhwar
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Rebecca Brown
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Danica B Stanimirovic
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Arsalan S Haqqani
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
- Edith Hamel, Laboratory of Cerebrovascular research, Montreal Neurological Institute, 3801 University St., Montréal, QC, H3A 2B4, Canada.
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76
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Nagai M, Hoshide S, Dote K, Kario K. Visit-to-visit blood pressure variability and dementia. Geriatr Gerontol Int 2016; 15 Suppl 1:26-33. [PMID: 26671154 DOI: 10.1111/ggi.12660] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2015] [Indexed: 11/28/2022]
Abstract
Visit-to-visit blood pressure variability has been shown to be an independent risk factor for stroke and cognitive impairment. However, the underlying mechanisms are not fully understood. Artery remodeling and silent cerebral injury are suggested to be involved in the relationship between visit-to-visit blood pressure variability and cognitive impairment. The present review article summarizes the recent literature on these topics. Here we review visit-to-visit blood pressure variability, artery remodeling, silent cerebral injury and an issue regarding the impact of these components on dementia including Alzheimer's disease.
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Affiliation(s)
- Michiaki Nagai
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Satoshi Hoshide
- Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Keigo Dote
- Department of Cardiology, Hiroshima City Asa Hospital, Hiroshima, Japan
| | - Kazuomi Kario
- Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University School of Medicine, Tochigi, Japan
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77
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Love S, Miners J. Cerebral Hypoperfusion and the Energy Deficit in Alzheimer's Disease. Brain Pathol 2016; 26:607-17. [PMID: 27327656 PMCID: PMC8028913 DOI: 10.1111/bpa.12401] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 06/21/2016] [Accepted: 05/25/2016] [Indexed: 12/19/2022] Open
Abstract
There is a perfusion deficit in Alzheimer's disease (AD), commencing in the precuneus and spreading to other parts of the cerebral cortex. The deficit anticipates the development of dementia, contributes to brain damage, and is caused by both functional and structural abnormalities of the cerebral vasculature. Most of the abnormalities are probably secondary to the accumulation of Aβ but the consequent hypoperfusion may, in turn, increase Aβ production. In the early stages of disease, abnormalities that cause vasoconstriction predominate. These include cholinergic vascular denervation, inhibition of endothelial nitric oxide synthase, increased production of endothelin-1 production and possibly also of angiotensin II. Patients with AD also have an increased prevalence of structural disease of cerebral microvessels, particularly CAA and capillary damage, and particularly in the later stages of disease these are likely to make an important contribution to the cerebral hypoperfusion. The metabolic abnormalities that cause early vascular dysfunction offer several targets for therapeutic intervention. However, for intervention to be effective it probably needs to be early. Prolonged cerebral hypoperfusion may induce compensatory circulatory changes that are themselves damaging, including hypertension and small vessel disease. This has implications for the use of antihypertensive drugs once there is accumulation of Aβ within the brain.
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Affiliation(s)
- Seth Love
- Dementia Research Group, Institute of Clinical Neurosciences, School of Clinical SciencesUniversity of BristolBristolUnited Kingom
| | - J.Scott Miners
- Dementia Research Group, Institute of Clinical Neurosciences, School of Clinical SciencesUniversity of BristolBristolUnited Kingom
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78
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Daulatzai MA. Dysfunctional Sensory Modalities, Locus Coeruleus, and Basal Forebrain: Early Determinants that Promote Neuropathogenesis of Cognitive and Memory Decline and Alzheimer’s Disease. Neurotox Res 2016; 30:295-337. [DOI: 10.1007/s12640-016-9643-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 12/22/2022]
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79
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Hamel E, Royea J, Ongali B, Tong XK. Neurovascular and Cognitive failure in Alzheimer’s Disease: Benefits of Cardiovascular Therapy. Cell Mol Neurobiol 2016; 36:219-32. [DOI: 10.1007/s10571-015-0285-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/06/2015] [Indexed: 12/19/2022]
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80
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Batarseh YS, Duong QV, Mousa YM, Al Rihani SB, Elfakhri K, Kaddoumi A. Amyloid-β and Astrocytes Interplay in Amyloid-β Related Disorders. Int J Mol Sci 2016; 17:338. [PMID: 26959008 PMCID: PMC4813200 DOI: 10.3390/ijms17030338] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 02/14/2016] [Accepted: 02/24/2016] [Indexed: 12/17/2022] Open
Abstract
Amyloid-β (Aβ) pathology is known to promote chronic inflammatory responses in the brain. It was thought previously that Aβ is only associated with Alzheimer's disease and Down syndrome. However, studies have shown its involvement in many other neurological disorders. The role of astrocytes in handling the excess levels of Aβ has been highlighted in the literature. Astrocytes have a distinctive function in both neuronal support and protection, thus its involvement in Aβ pathological process may tip the balance toward chronic inflammation and neuronal death. In this review we describe the involvement of astrocytes in Aβ related disorders including Alzheimer's disease, Down syndrome, cerebral amyloid angiopathy, and frontotemporal dementia.
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Affiliation(s)
- Yazan S Batarseh
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA 70504, USA.
| | - Quoc-Viet Duong
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA 70504, USA.
| | - Youssef M Mousa
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA 70504, USA.
| | - Sweilem B Al Rihani
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA 70504, USA.
| | - Khaled Elfakhri
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA 70504, USA.
| | - Amal Kaddoumi
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA 70504, USA.
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81
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Iadecola C. Vascular and Metabolic Factors in Alzheimer's Disease and Related Dementias: Introduction. Cell Mol Neurobiol 2016; 36:151-4. [PMID: 26898551 PMCID: PMC4846525 DOI: 10.1007/s10571-015-0319-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 12/15/2015] [Indexed: 01/14/2023]
Affiliation(s)
- Costantino Iadecola
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, 407 East 61st Street, New York, NY, 10065, USA.
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82
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Østergaard L, Engedal TS, Moreton F, Hansen MB, Wardlaw JM, Dalkara T, Markus HS, Muir KW. Cerebral small vessel disease: Capillary pathways to stroke and cognitive decline. J Cereb Blood Flow Metab 2016; 36:302-25. [PMID: 26661176 PMCID: PMC4759673 DOI: 10.1177/0271678x15606723] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 07/30/2015] [Indexed: 01/18/2023]
Abstract
Cerebral small vessel disease (SVD) gives rise to one in five strokes worldwide and constitutes a major source of cognitive decline in the elderly. SVD is known to occur in relation to hypertension, diabetes, smoking, radiation therapy and in a range of inherited and genetic disorders, autoimmune disorders, connective tissue disorders, and infections. Until recently, changes in capillary patency and blood viscosity have received little attention in the aetiopathogenesis of SVD and the high risk of subsequent stroke and cognitive decline. Capillary flow patterns were, however, recently shown to limit the extraction efficacy of oxygen in tissue and capillary dysfunction therefore proposed as a source of stroke-like symptoms and neurodegeneration, even in the absence of physical flow-limiting vascular pathology. In this review, we examine whether capillary flow disturbances may be a shared feature of conditions that represent risk factors for SVD. We then discuss aspects of capillary dysfunction that could be prevented or alleviated and therefore might be of general benefit to patients at risk of SVD, stroke or cognitive decline.
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Affiliation(s)
- Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark
| | - Thorbjørn S Engedal
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Fiona Moreton
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Mikkel B Hansen
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Joanna M Wardlaw
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry and Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Hugh S Markus
- Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Keith W Muir
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
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83
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Reynolds MR, Singh I, Azad TD, Holmes BB, Verghese PB, Dietrich HH, Diamond M, Bu G, Han BH, Zipfel GJ. Heparan sulfate proteoglycans mediate Aβ-induced oxidative stress and hypercontractility in cultured vascular smooth muscle cells. Mol Neurodegener 2016; 11:9. [PMID: 26801396 PMCID: PMC4722750 DOI: 10.1186/s13024-016-0073-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 01/12/2016] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Substantial evidence suggests that amyloid-β (Aβ) species induce oxidative stress and cerebrovascular (CV) dysfunction in Alzheimer's disease (AD), potentially contributing to the progressive dementia of this disease. The upstream molecular pathways governing this process, however, are poorly understood. In this report, we examine the role of heparan sulfate proteoglycans (HSPG) in Aβ-induced vascular smooth muscle cell (VSMC) dysfunction in vitro. RESULTS Our results demonstrate that pharmacological depletion of HSPG (by enzymatic degradation with active, but not heat-inactivated, heparinase) in primary human cerebral and transformed rat VSMC mitigates Aβ(1-40⁻) and Aβ(1-42⁻)induced oxidative stress. This inhibitory effect is specific for HSPG depletion and does not occur with pharmacological depletion of other glycosaminoglycan (GAG) family members. We also found that Aβ(1-40) (but not Aβ(1-42)) causes a hypercontractile phenotype in transformed rat cerebral VSMC that likely results from a HSPG-mediated augmentation in intracellular Ca(2+) activity, as both Aβ(1-40⁻)induced VSMC hypercontractility and increased Ca(2+) influx are inhibited by pharmacological HSPG depletion. Moreover, chelation of extracellular Ca(2+) with ethylene glycol tetraacetic acid (EGTA) does not prevent the production of Aβ(1-40⁻) or Aβ(1-42⁻)mediated reactive oxygen species (ROS), suggesting that Aβ-induced ROS and VSMC hypercontractility occur through different molecular pathways. CONCLUSIONS Taken together, our data indicate that HSPG are critical mediators of Aβ-induced oxidative stress and Aβ(1-40⁻)induced VSMC dysfunction.
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Affiliation(s)
- Matthew R Reynolds
- Department of Neurological Surgery, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Campus Box 8057, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Itender Singh
- Department of Neurological Surgery, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Campus Box 8057, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Tej D Azad
- Department of Neurological Surgery, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Campus Box 8057, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Brandon B Holmes
- Department of Neurology, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, St. Louis, Missouri, USA
| | - Phillip B Verghese
- Department of Neurology, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, St. Louis, Missouri, USA
| | - Hans H Dietrich
- Department of Neurological Surgery, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Campus Box 8057, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Marc Diamond
- Center for Alzheimer's and Neurodegenerative Diseases, UT Southwestern, Dallas, Texas, USA
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA
| | - Byung Hee Han
- Department of Pharmacology, AT Still University Health Sciences, Kirksville, Missouri, USA
| | - Gregory J Zipfel
- Department of Neurological Surgery, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Campus Box 8057, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA.
- Department of Neurology, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, St. Louis, Missouri, USA.
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84
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Iulita MF, Girouard H. Treating Hypertension to Prevent Cognitive Decline and Dementia: Re-Opening the Debate. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 956:447-473. [DOI: 10.1007/5584_2016_98] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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85
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Yang SH, Li W, Sumien N, Forster M, Simpkins JW, Liu R. Alternative mitochondrial electron transfer for the treatment of neurodegenerative diseases and cancers: Methylene blue connects the dots. Prog Neurobiol 2015; 157:273-291. [PMID: 26603930 DOI: 10.1016/j.pneurobio.2015.10.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 09/10/2015] [Accepted: 10/20/2015] [Indexed: 12/21/2022]
Abstract
Brain has exceptional high requirement for energy metabolism with glucose as the exclusive energy source. Decrease of brain energy metabolism and glucose uptake has been found in patients of Alzheimer's, Parkinson's and other neurodegenerative diseases, providing a clear link between neurodegenerative disorders and energy metabolism. On the other hand, cancers, including glioblastoma, have increased glucose uptake and rely on aerobic glycolysis for energy metabolism. The switch of high efficient oxidative phosphorylation to low efficient aerobic glycolysis pathway (Warburg effect) provides macromolecule for biosynthesis and proliferation. Current research indicates that methylene blue, a century old drug, can receive electron from NADH in the presence of complex I and donates it to cytochrome c, providing an alternative electron transfer pathway. Methylene blue increases oxygen consumption, decrease glycolysis, and increases glucose uptake in vitro. Methylene blue enhances glucose uptake and regional cerebral blood flow in rats upon acute treatment. In addition, methylene blue provides protective effect in neuron and astrocyte against various insults in vitro and in rodent models of Alzheimer's, Parkinson's, and Huntington's disease. In glioblastoma cells, methylene blue reverses Warburg effect by enhancing mitochondrial oxidative phosphorylation, arrests glioma cell cycle at s-phase, and inhibits glioma cell proliferation. Accordingly, methylene blue activates AMP-activated protein kinase, inhibits downstream acetyl-coA carboxylase and cyclin-dependent kinases. In summary, there is accumulating evidence providing a proof of concept that enhancement of mitochondrial oxidative phosphorylation via alternative mitochondrial electron transfer may offer protective action against neurodegenerative diseases and inhibit cancers proliferation.
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Affiliation(s)
- Shao-Hua Yang
- Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
| | - Wenjun Li
- Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Nathalie Sumien
- Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Michael Forster
- Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - James W Simpkins
- Department of Physiology and Pharmacology, Center for Neuroscience, Health Science Center, West Virginia University, Medical Center Drive, Morgantown, WV 26506, USA
| | - Ran Liu
- Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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86
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Endothelial Dysfunction and Amyloid-β-Induced Neurovascular Alterations. Cell Mol Neurobiol 2015; 36:155-65. [PMID: 26328781 DOI: 10.1007/s10571-015-0256-9] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 08/20/2015] [Indexed: 01/08/2023]
Abstract
Alzheimer's disease (AD) and cerebrovascular diseases share common vascular risk factors that have disastrous effects on cerebrovascular regulation. Endothelial cells, lining inner walls of cerebral blood vessels, form a dynamic interface between the blood and the brain and are critical for the maintenance of neurovascular homeostasis. Accordingly, injury in endothelial cells is regarded as one of the earliest symptoms of impaired vasoregulatory mechanisms. Extracellular buildup of amyloid-β (Aβ) is a central pathogenic factor in AD. Aβ exerts potent detrimental effects on cerebral blood vessels and impairs endothelial structure and function. Recent evidence implicates vascular oxidative stress and activation of the non-selective cationic channel transient receptor potential melastatin (TRPM)-2 on endothelial cells in the mechanisms of Aβ-induced neurovascular dysfunction. Thus, Aβ triggers opening of TRPM2 channels in endothelial cells leading to intracellular Ca(2+) overload and vasomotor dysfunction. The cerebrovascular dysfunction may contribute to AD pathogenesis by reducing the cerebral blood supply, leading to increased susceptibility to vascular insufficiency, and by promoting Aβ accumulation. The recent realization that vascular factors contribute to AD pathobiology suggests new targets for the prevention and treatment of this devastating disease.
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87
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Comparison of stimulus-evoked cerebral hemodynamics in the awake mouse and under a novel anesthetic regime. Sci Rep 2015. [PMID: 26218081 PMCID: PMC4517464 DOI: 10.1038/srep12621] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neural activity is closely followed by a localised change in cerebral blood flow, a process termed neurovascular coupling. These hemodynamic changes form the basis of contrast in functional magnetic resonance imaging (fMRI) and are used as a correlate for neural activity. Anesthesia is widely employed in animal fMRI and neurovascular studies, however anesthetics are known to profoundly affect neural and vascular physiology, particularly in mice. Therefore, we investigated the efficacy of a novel ‘modular’ anesthesia that combined injectable (fentanyl-fluanisone/midazolam) and volatile (isoflurane) anesthetics in mice. To characterize sensory-evoked cortical hemodynamic responses, we used optical imaging spectroscopy to produce functional maps of changes in tissue oxygenation and blood volume in response to mechanical whisker stimulation. Following fine-tuning of the anesthetic regime, stimulation elicited large and robust hemodynamic responses in the somatosensory cortex, characterized by fast arterial activation, increases in total and oxygenated hemoglobin, and decreases in deoxygenated hemoglobin. Overall, the magnitude and speed of evoked hemodynamic responses under anesthesia resembled those in the awake state, indicating that the novel anesthetic combination significantly minimizes the impact of anesthesia. Our findings have broad implications for both neurovascular research and longitudinal fMRI studies that increasingly require the use of genetically engineered mice.
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Winkler EA, Sagare AP, Zlokovic BV. The pericyte: a forgotten cell type with important implications for Alzheimer's disease? Brain Pathol 2015; 24:371-86. [PMID: 24946075 DOI: 10.1111/bpa.12152] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 05/13/2014] [Indexed: 12/13/2022] Open
Abstract
Pericytes are cells in the blood-brain barrier (BBB) that degenerate in Alzheimer's disease (AD), a neurodegenerative disorder characterized by early neurovascular dysfunction, elevation of amyloid β-peptide (Aβ), tau pathology and neuronal loss, leading to progressive cognitive decline and dementia. Pericytes are uniquely positioned within the neurovascular unit between endothelial cells of brain capillaries, astrocytes and neurons. Recent studies have shown that pericytes regulate key neurovascular functions including BBB formation and maintenance, vascular stability and angioarchitecture, regulation of capillary blood flow, and clearance of toxic cellular by-products necessary for normal functioning of the central nervous system (CNS). Here, we review the concept of the neurovascular unit and neurovascular functions of CNS pericytes. Next, we discuss vascular contributions to AD and review new roles of pericytes in the pathogenesis of AD such as vascular-mediated Aβ-independent neurodegeneration, regulation of Aβ clearance and contributions to tau pathology, neuronal loss and cognitive decline. We conclude that future studies should focus on molecular mechanisms and pathways underlying aberrant signal transduction between pericytes and its neighboring cells within the neurovascular unit, that is, endothelial cells, astrocytes and neurons, which could represent potential therapeutic targets to control pericyte degeneration in AD and the resulting secondary vascular and neuronal degeneration.
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Affiliation(s)
- Ethan A Winkler
- Zilkha Neurogenetic Institute, University of Southern California Keck School of Medicine, Los Angeles, CA; Department of Neurosurgery, University of California San Francisco, San Francisco, CA
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89
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Gupta A, Iadecola C. Impaired Aβ clearance: a potential link between atherosclerosis and Alzheimer's disease. Front Aging Neurosci 2015; 7:115. [PMID: 26136682 PMCID: PMC4468824 DOI: 10.3389/fnagi.2015.00115] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 05/29/2015] [Indexed: 11/14/2022] Open
Abstract
Alzheimer’s Disease (AD) and atherosclerosis remain two of the largest public health burdens in the world today. Although traditionally considered distinct pathological entities, mounting epidemiologic, clinical and experimental evidence suggests that cerebrovascular atherosclerosis and AD interact reciprocally to disrupt brain structure and function. Whereas the hypoperfusion and hypoxia caused by atherosclerosis of cerebral vessels may enhance the production of amyloid-β peptide (Aβ), a peptide central to AD pathology, Aβ, in turn, may promote formation of atherosclerotic lesions through vascular oxidative stress and endothelial dysfunction leading to additional vascular damage. Here, we briefly review evidence suggesting that impaired clearance of Aβ is an additional, simultaneously occurring mechanism by which AD and cerebrovascular disease may be causally linked. We examine the literature supporting mechanisms by which flow-limiting large-artery stenosis, arterial stiffening and microvascular dysfunction could contribute to AD pathophysiology by impairing Aβ clearance and elevating brain levels of Aβ. Finally, we highlight the need for further research to improve our understanding of the complex interactions of AD and atherosclerosis with Aβ clearance, which may ultimately serve to guide the development of novel diagnostic and therapeutic approaches for this devastating and highly prevalent condition.
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Affiliation(s)
- Ajay Gupta
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College New York, NY, USA ; Department of Radiology, Weill Cornell Medical College New York, NY, USA
| | - Costantino Iadecola
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College New York, NY, USA
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90
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Lourenço CF, Ledo A, Dias C, Barbosa RM, Laranjinha J. Neurovascular and neurometabolic derailment in aging and Alzheimer's disease. Front Aging Neurosci 2015; 7:103. [PMID: 26074816 PMCID: PMC4445047 DOI: 10.3389/fnagi.2015.00103] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/13/2015] [Indexed: 12/17/2022] Open
Abstract
The functional and structural integrity of the brain requires local adjustment of blood flow and regulated delivery of metabolic substrates to meet the metabolic demands imposed by neuronal activation. This process—neurovascular coupling—and ensued alterations of glucose and oxygen metabolism—neurometabolic coupling—are accomplished by concerted communication between neural and vascular cells. Evidence suggests that neuronal-derived nitric oxide (•NO) is a key player in both phenomena. Alterations in the mechanisms underlying the intimate communication between neural cells and vessels ultimately lead to neuronal dysfunction. Both neurovascular and neurometabolic coupling are perturbed during brain aging and in age-related neuropathologies in close association with cognitive decline. However, despite decades of intense investigation, many aspects remain poorly understood, such as the impact of these alterations. In this review, we address neurovascular and neurometabolic derailment in aging and Alzheimer's disease (AD), discussing its significance in connection with •NO-related pathways.
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Affiliation(s)
- Cátia F Lourenço
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Ana Ledo
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Cândida Dias
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Rui M Barbosa
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Faculty of Pharmacy, University of Coimbra Coimbra, Portugal
| | - João Laranjinha
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Faculty of Pharmacy, University of Coimbra Coimbra, Portugal
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91
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92
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Winkler EA, Nishida Y, Sagare AP, Rege SV, Bell RD, Perlmutter D, Sengillo JD, Hillman S, Kong P, Nelson AR, Sullivan JS, Zhao Z, Meiselman HJ, Wendy RB, Soto J, Abel ED, Makshanoff J, Zuniga E, De Vivo DC, Zlokovic BV. GLUT1 reductions exacerbate Alzheimer's disease vasculo-neuronal dysfunction and degeneration. Nat Neurosci 2015; 18:521-530. [PMID: 25730668 PMCID: PMC4734893 DOI: 10.1038/nn.3966] [Citation(s) in RCA: 442] [Impact Index Per Article: 49.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 01/30/2015] [Indexed: 12/13/2022]
Abstract
The glucose transporter GLUT1 at the blood-brain barrier (BBB) mediates glucose transport into the brain. Alzheimer's disease is characterized by early reductions in glucose transport associated with diminished GLUT1 expression at the BBB. Whether GLUT1 reduction influences disease pathogenesis remains, however, elusive. Here we show that GLUT1 deficiency in mice overexpressing amyloid β-peptide (Aβ) precursor protein leads to early cerebral microvascular degeneration, blood flow reductions and dysregulation and BBB breakdown, and to accelerated amyloid β-peptide (Aβ) pathology, reduced Aβ clearance, diminished neuronal activity, behavioral deficits, and progressive neuronal loss and neurodegeneration that develop after initial cerebrovascular degenerative changes. We also show that GLUT1 deficiency in endothelium, but not in astrocytes, initiates the vascular phenotype as shown by BBB breakdown. Thus, reduced BBB GLUT1 expression worsens Alzheimer's disease cerebrovascular degeneration, neuropathology and cognitive function, suggesting that GLUT1 may represent a therapeutic target for Alzheimer's disease vasculo-neuronal dysfunction and degeneration.
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Affiliation(s)
- Ethan A. Winkler
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA
| | - Yoichiro Nishida
- Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester School of Medicine & Dentistry, Rochester, NY
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Abhay P. Sagare
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Sanket V. Rege
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Robert D. Bell
- Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester School of Medicine & Dentistry, Rochester, NY
| | - David Perlmutter
- Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester School of Medicine & Dentistry, Rochester, NY
| | - Jesse D. Sengillo
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
- Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester School of Medicine & Dentistry, Rochester, NY
| | - Sara Hillman
- Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester School of Medicine & Dentistry, Rochester, NY
| | - Pan Kong
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Amy R. Nelson
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - John S. Sullivan
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Zhen Zhao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Herbert J. Meiselman
- Departrment of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Rosalinda B. Wendy
- Departrment of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Jamie Soto
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - E. Dale Abel
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Jacob Makshanoff
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Edward Zuniga
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Darryl C. De Vivo
- Colleen Giblin Laboratories for Pediatric Neurology Research, Columbia University New York, NY, USA
| | - Berislav V. Zlokovic
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
- Departrment of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA
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93
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Contribution of reactive oxygen species to cerebral amyloid angiopathy, vasomotor dysfunction, and microhemorrhage in aged Tg2576 mice. Proc Natl Acad Sci U S A 2015; 112:E881-90. [PMID: 25675483 DOI: 10.1073/pnas.1414930112] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Cerebral amyloid angiopathy (CAA) is characterized by deposition of amyloid β peptide (Aβ) within walls of cerebral arteries and is an important cause of intracerebral hemorrhage, ischemic stroke, and cognitive dysfunction in elderly patients with and without Alzheimer's Disease (AD). NADPH oxidase-derived oxidative stress plays a key role in soluble Aβ-induced vessel dysfunction, but the mechanisms by which insoluble Aβ in the form of CAA causes cerebrovascular (CV) dysfunction are not clear. Here, we demonstrate evidence that reactive oxygen species (ROS) and, in particular, NADPH oxidase-derived ROS are a key mediator of CAA-induced CV deficits. First, the NADPH oxidase inhibitor, apocynin, and the nonspecific ROS scavenger, tempol, are shown to reduce oxidative stress and improve CV reactivity in aged Tg2576 mice. Second, the observed improvement in CV function is attributed both to a reduction in CAA formation and a decrease in CAA-induced vasomotor impairment. Third, anti-ROS therapy attenuates CAA-related microhemorrhage. A potential mechanism by which ROS contribute to CAA pathogenesis is also identified because apocynin substantially reduces expression levels of ApoE-a factor known to promote CAA formation. In total, these data indicate that ROS are a key contributor to CAA formation, CAA-induced vessel dysfunction, and CAA-related microhemorrhage. Thus, ROS and, in particular, NADPH oxidase-derived ROS are a promising therapeutic target for patients with CAA and AD.
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94
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Park L, Wang G, Moore J, Girouard H, Zhou P, Anrather J, Iadecola C. The key role of transient receptor potential melastatin-2 channels in amyloid-β-induced neurovascular dysfunction. Nat Commun 2014; 5:5318. [PMID: 25351853 DOI: 10.1038/ncomms6318] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/19/2014] [Indexed: 01/18/2023] Open
Abstract
Alzheimer's dementia is a devastating and incurable disease afflicting over 35 million people worldwide. Amyloid-β (Aβ), a key pathogenic factor in this disease, has potent cerebrovascular effects that contribute to brain dysfunction underlying dementia by limiting the delivery of oxygen and glucose to the working brain. However, the downstream pathways responsible for the vascular alterations remain unclear. Here we report that the cerebrovascular dysfunction induced by Aβ is mediated by DNA damage caused by vascular oxidative-nitrosative stress in cerebral endothelial cells, which, in turn, activates the DNA repair enzyme poly(ADP)-ribose polymerase. The resulting increase in ADP ribose opens transient receptor potential melastatin-2 (TRPM2) channels in endothelial cells leading to intracellular Ca(2+) overload and endothelial dysfunction. The findings provide evidence for a previously unrecognized mechanism by which Aβ impairs neurovascular regulation and suggest that TRPM2 channels are a potential therapeutic target to counteract cerebrovascular dysfunction in Alzheimer's dementia and related pathologies.
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Affiliation(s)
- L Park
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
| | - G Wang
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
| | - J Moore
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
| | - H Girouard
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
| | - P Zhou
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
| | - J Anrather
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
| | - C Iadecola
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York 10065, USA
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95
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Erb L, Cao C, Ajit D, Weisman GA. P2Y receptors in Alzheimer's disease. Biol Cell 2014; 107:1-21. [PMID: 25179475 DOI: 10.1111/boc.201400043] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 08/27/2014] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia, affecting more than 10% of people over the age of 65. Age is the greatest risk factor for AD, although a combination of genetic, lifestyle and environmental factors also contribute to disease development. Common features of AD are the formation of plaques composed of beta-amyloid peptides (Aβ) and neuronal death in brain regions involved in learning and memory. Although Aβ is neurotoxic, the primary mechanisms by which Aβ affects AD development remain uncertain and controversial. Mouse models overexpressing amyloid precursor protein and Aβ have revealed that Aβ has potent effects on neuroinflammation and cerebral blood flow that contribute to AD progression. Therefore, it is important to consider how endogenous signalling in the brain responds to Aβ and contributes to AD pathology. In recent years, Aβ has been shown to affect ATP release from brain and blood cells and alter the expression of G protein-coupled P2Y receptors that respond to ATP and other nucleotides. Accumulating evidence reveals a prominent role for P2Y receptors in AD pathology, including Aβ production and elimination, neuroinflammation, neuronal function and cerebral blood flow.
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Affiliation(s)
- Laurie Erb
- Department of Biochemistry, Life Sciences Center, University of Missouri, Columbia, MO, 65211, U.S.A
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96
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De Bock M, Decrock E, Wang N, Bol M, Vinken M, Bultynck G, Leybaert L. The dual face of connexin-based astroglial Ca(2+) communication: a key player in brain physiology and a prime target in pathology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2211-32. [PMID: 24768716 DOI: 10.1016/j.bbamcr.2014.04.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
For decades, studies have been focusing on the neuronal abnormalities that accompany neurodegenerative disorders. Yet, glial cells are emerging as important players in numerous neurological diseases. Astrocytes, the main type of glia in the central nervous system , form extensive networks that physically and functionally connect neuronal synapses with cerebral blood vessels. Normal brain functioning strictly depends on highly specialized cellular cross-talk between these different partners to which Ca(2+), as a signaling ion, largely contributes. Altered intracellular Ca(2+) levels are associated with neurodegenerative disorders and play a crucial role in the glial responses to injury. Intracellular Ca(2+) increases in single astrocytes can be propagated toward neighboring cells as intercellular Ca(2+) waves, thereby recruiting a larger group of cells. Intercellular Ca(2+) wave propagation depends on two, parallel, connexin (Cx) channel-based mechanisms: i) the diffusion of inositol 1,4,5-trisphosphate through gap junction channels that directly connect the cytoplasm of neighboring cells, and ii) the release of paracrine messengers such as glutamate and ATP through hemichannels ('half of a gap junction channel'). This review gives an overview of the current knowledge on Cx-mediated Ca(2+) communication among astrocytes as well as between astrocytes and other brain cell types in physiology and pathology, with a focus on the processes of neurodegeneration and reactive gliosis. Research on Cx-mediated astroglial Ca(2+) communication may ultimately shed light on the development of targeted therapies for neurodegenerative disorders in which astrocytes participate. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Center for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, B-1090 Brussels, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N-I bus 802, B-3000 Leuven, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
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97
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Abstract
Cerebrovascular dysfunction significantly contributes to the clinical presentation and pathoetiology of Alzheimer's disease (AD). Deposition and aggregation of β-amyloid (Aβ) within vascular smooth muscle cells leads to inflammation, oxidative stress, impaired vasorelaxation, and disruption of blood-brain barrier integrity. Midlife vascular risk factors, such as hypertension, cardiovascular disease, diabetes, and dyslipidemia, increase the relative risk for AD. These comorbidities are all characterized by low and/or dysfunctional high-density lipoproteins (HDL), which itself is a risk factor for AD. HDL performs a wide variety of critical functions in the periphery and CNS. In addition to lipid transport, HDL regulates vascular health via mediating vasorelaxation, inflammation, and oxidative stress and promotes endothelial cell survival and integrity. Here, we summarize clinical and preclinical data examining the involvement of HDL, originating from the circulation and from within the CNS, on AD and hypothesize potential synergistic actions between the two lipoprotein pools.
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98
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Sato N, Morishita R. Brain alterations and clinical symptoms of dementia in diabetes: aβ/tau-dependent and independent mechanisms. Front Endocrinol (Lausanne) 2014; 5:143. [PMID: 25250014 PMCID: PMC4155814 DOI: 10.3389/fendo.2014.00143] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 08/15/2014] [Indexed: 12/31/2022] Open
Abstract
Emerging evidence suggests that diabetes affects cognitive function and increases the incidence of dementia. However, the mechanisms by which diabetes modifies cognitive function still remains unclear. Morphologically, diabetes is associated with neuronal loss in the frontal and temporal lobes including the hippocampus, and aberrant functional connectivity of the posterior cingulate cortex and medial frontal/temporal gyrus. Clinically, diabetic patients show decreased executive function, information processing, planning, visuospatial construction, and visual memory. Therefore, in comparison with the characteristics of AD brain structure and cognition, diabetes seems to affect cognitive function through not only simple AD pathological feature-dependent mechanisms but also independent mechanisms. As an Aβ/tau-independent mechanism, diabetes compromises cerebrovascular function, increases subcortical infarction, and might alter the blood-brain barrier. Diabetes also affects glucose metabolism, insulin signaling, and mitochondrial function in the brain. Diabetes also modifies metabolism of Aβ and tau and causes Aβ/tau-dependent pathological changes. Moreover, there is evidence that suggests an interaction between Aβ/tau-dependent and independent mechanisms. Therefore, diabetes modifies cognitive function through Aβ/tau-dependent and independent mechanisms. Interaction between these two mechanisms forms a vicious cycle.
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Affiliation(s)
- Naoyuki Sato
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka University, Osaka, Japan
- Department of Geriatric Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
- *Correspondence: Naoyuki Sato, Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan e-mail:
| | - Ryuichi Morishita
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka University, Osaka, Japan
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99
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Thomason LAM, Stefanovic B, McLaurin J. Cerebrovascular contributions to Alzheimer's disease pathophysiology and potential therapeutic interventions in mouse models. Eur J Neurosci 2013; 37:1994-2004. [PMID: 23773069 DOI: 10.1111/ejn.12181] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 02/08/2013] [Accepted: 02/11/2013] [Indexed: 10/26/2022]
Abstract
The inter-relationship between vascular dysfunction and Alzheimer's disease pathology is not clearly understood; however, it is clear that the accumulation of amyloid-beta peptide and loss of vascular function contribute to the cognitive decline detected in patients. At present, imaging modalities can monitor the downstream effects of vascular dysfunction such as cerebral blood flow alterations, white and gray matter lacunes, and ischemic lesions; however, they cannot distinguish parenchymal plaques from cerebrovascular amyloid. Much of our understanding regarding the relationship between amyloid and vascular dysfunction has come from longitudinal population studies and mouse models. In this review, we will discuss the breadth of data generated on vascular function in mouse models of Alzheimer's disease and cerebrovascular amyloid angiopathy. We will also discuss therapeutic strategies targeting the reduction of cerebrovascular amyloid angiopathy and improvement of vascular function.
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Affiliation(s)
- Lynsie A M Thomason
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
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100
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Watson D, Castaño E, Kokjohn TA, Kuo YM, Lyubchenko Y, Pinsky D, Connolly ES, Esh C, Luehrs DC, Stine WB, Rowse LM, Emmerling MR, Roher AE. Physicochemical characteristics of soluble oligomeric Aβand their pathologic role in Alzheimer's disease. Neurol Res 2013; 27:869-81. [PMID: 16354549 DOI: 10.1179/016164105x49436] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extracellular fibrillar amyloid deposits are prominent and universal Alzheimer's disease (AD) features, but senile plaque abundance does not always correlate directly with the degree of dementia exhibited by AD patients. The mechanism(s) and dynamics of Abeta fibril genesis and deposition remain obscure. Enhanced Abeta synthesis rates coupled with decreased degradative enzyme production and accumulating physical modifications that dampen proteolysis may all enhance amyloid deposit formation. Amyloid accumulation may indirectly exert the greatest pathologic effect on the brain vasculature by destroying smooth muscle cells and creating a cascade of negative impacts on cerebral blood flow. The most visible manifestation of amyloid dis-equilibrium could actually be a defense mechanism employed to avoid serious vascular wall degradation while the major toxic effects to the gray and white matter neurons are mediated by soluble oligomeric Abeta peptides with high beta-sheet content. The recognition that dynamic soluble oligomeric Abeta pools exist in AD and are correlated to disease severity led to neurotoxicity and physical conformation studies. It is now recognized that the most basic soluble Abeta peptides are stable dimers with hydrophobic regions sequestered from the aqueous environment and are capable of higher order aggregations. Time course experiments employing a modified ELISA method able to detect Abeta oligomers revealed dynamic intermolecular interactions and additional experiments physically confirmed the presence of stable amyloid multimers. Amyloid peptides that are rich in beta-sheet structure are capable of creating toxic membrane ion channels and a capacity to self-assemble as annular structures was confirmed in vitro using atomic force microscopy. Biochemical studies have established that soluble Abeta peptides perturb metabolic processes, provoke release of deleterious reactive compounds, reduce blood flow, induce mitochondrial apoptotic toxicity and inhibit angiogenesis. While there is no question that gross amyloid deposition does contribute to AD pathology, the destructive potential now associated with soluble Abeta suggests that treatment strategies that target these molecules may be efficacious in preventing some of the devastating effects of AD.
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Affiliation(s)
- Desiree Watson
- Pfizer, Global Research and Development, Ann Arbor, MI 48106 USA
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