1
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Smets NG, Strijkers GJ, Vinje V, Bakker ENTP. Cerebrospinal fluid turnover as a driver of brain clearance. NMR IN BIOMEDICINE 2024; 37:e5029. [PMID: 37658736 DOI: 10.1002/nbm.5029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/30/2023] [Accepted: 08/05/2023] [Indexed: 09/05/2023]
Abstract
Cerebrospinal fluid (CSF) has historically been considered to function as a sink for brain-derived waste disposal. Recent work suggested that CSF interacts even more intensely with brain tissue than previously recognized, through perivascular spaces that penetrate the brain. Cardiac pulsations, vasomotion, and respiration have been suggested to drive CSF flow in these perivascular spaces, thereby enhancing waste clearance. However, the intrinsic role of CSF production in relation to its distribution volume (turnover) is not an explicit component of recent concepts on brain clearance. Here, we review the work on CSF turnover and volume, focusing on preclinical evidence. Herein, we highlight the use of MRI in establishing CSF-related parameters. We describe the impact of sleep, effect of anesthesia, aging, and hypertension on CSF turnover, and how this relates to brain clearance. Evaluation of the available evidence suggests that CSF turnover is a major determinant in brain clearance. In addition, we propose that several putative drivers of brain clearance, but also conditions associated with impaired clearance, such as aging, may actually relate to altered CSF turnover.
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Affiliation(s)
- Nina G Smets
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, the Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, the Netherlands
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, the Netherlands
| | | | - Erik N T P Bakker
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, the Netherlands
- Amsterdam Cardiovascular Sciences Research Institute, Amsterdam, the Netherlands
- Amsterdam Neuroscience Research Institute, Amsterdam, the Netherlands
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2
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Bojarskaite L, Nafari S, Ravnanger AK, Frey MM, Skauli N, Åbjørsbråten KS, Roth LC, Amiry-Moghaddam M, Nagelhus EA, Ottersen OP, Bogen IL, Thoren AE, Enger R. Role of aquaporin-4 polarization in extracellular solute clearance. Fluids Barriers CNS 2024; 21:28. [PMID: 38532513 DOI: 10.1186/s12987-024-00527-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 03/02/2024] [Indexed: 03/28/2024] Open
Abstract
Waste from the brain has been shown to be cleared via the perivascular spaces through the so-called glymphatic system. According to this model the cerebrospinal fluid (CSF) enters the brain in perivascular spaces of arteries, crosses the astrocyte endfoot layer, flows through the parenchyma collecting waste that is subsequently drained along veins. Glymphatic clearance is dependent on astrocytic aquaporin-4 (AQP4) water channels that are highly enriched in the endfeet. Even though the polarized expression of AQP4 in endfeet is thought to be of crucial importance for glymphatic CSF influx, its role in extracellular solute clearance has only been evaluated using non-quantitative fluorescence measurements. Here we have quantitatively evaluated clearance of intrastriatally infused small and large radioactively labeled solutes in mice lacking AQP4 (Aqp4-/-) or lacking the endfoot pool of AQP4 (Snta1-/-). We confirm that Aqp4-/- mice show reduced clearance of both small and large extracellular solutes. Moreover, we find that the Snta1-/- mice have reduced clearance only for the 500 kDa [3H]dextran, but not 0.18 kDa [3H]mannitol suggesting that polarization of AQP4 to the endfeet is primarily important for clearance of large, but not small molecules. Lastly, we observed that clearance of 500 kDa [3H]dextran increased with age in adult mice. Based on our quantitative measurements, we confirm that presence of AQP4 is important for clearance of extracellular solutes, while the perivascular AQP4 localization seems to have a greater impact on clearance of large versus small molecules.
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Affiliation(s)
- Laura Bojarskaite
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
- Department of Neurology, Oslo University Hospital, Oslo, 0027, Norway
| | - Sahar Nafari
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Anne Katrine Ravnanger
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Mina Martine Frey
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway
| | - Nadia Skauli
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway
| | - Knut Sindre Åbjørsbråten
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Lena Catherine Roth
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Mahmood Amiry-Moghaddam
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway
| | - Erlend A Nagelhus
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Ole Petter Ottersen
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Inger Lise Bogen
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
- Section for Drug Abuse Research, Department of Forensic Sciences, Oslo University Hospital, P.O. Box N-4950, Nydalen, Oslo, 0424, Norway
| | - Anna E Thoren
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway
| | - Rune Enger
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O.B. 1103, Oslo, 0317, Norway.
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3
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Jiang-Xie LF, Drieu A, Bhasiin K, Quintero D, Smirnov I, Kipnis J. Neuronal dynamics direct cerebrospinal fluid perfusion and brain clearance. Nature 2024; 627:157-164. [PMID: 38418877 DOI: 10.1038/s41586-024-07108-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024]
Abstract
The accumulation of metabolic waste is a leading cause of numerous neurological disorders, yet we still have only limited knowledge of how the brain performs self-cleansing. Here we demonstrate that neural networks synchronize individual action potentials to create large-amplitude, rhythmic and self-perpetuating ionic waves in the interstitial fluid of the brain. These waves are a plausible mechanism to explain the correlated potentiation of the glymphatic flow1,2 through the brain parenchyma. Chemogenetic flattening of these high-energy ionic waves largely impeded cerebrospinal fluid infiltration into and clearance of molecules from the brain parenchyma. Notably, synthesized waves generated through transcranial optogenetic stimulation substantially potentiated cerebrospinal fluid-to-interstitial fluid perfusion. Our study demonstrates that neurons serve as master organizers for brain clearance. This fundamental principle introduces a new theoretical framework for the functioning of macroscopic brain waves.
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Affiliation(s)
- Li-Feng Jiang-Xie
- Brain Immunology and Glia (BIG) Center, Washington University in St Louis, St Louis, MO, USA.
- Department of Pathology and Immunology, School of Medicine, Washington University in St Louis, St Louis, MO, USA.
| | - Antoine Drieu
- Brain Immunology and Glia (BIG) Center, Washington University in St Louis, St Louis, MO, USA
- Department of Pathology and Immunology, School of Medicine, Washington University in St Louis, St Louis, MO, USA
| | - Kesshni Bhasiin
- Brain Immunology and Glia (BIG) Center, Washington University in St Louis, St Louis, MO, USA
- Department of Pathology and Immunology, School of Medicine, Washington University in St Louis, St Louis, MO, USA
| | - Daniel Quintero
- Brain Immunology and Glia (BIG) Center, Washington University in St Louis, St Louis, MO, USA
- Department of Pathology and Immunology, School of Medicine, Washington University in St Louis, St Louis, MO, USA
| | - Igor Smirnov
- Brain Immunology and Glia (BIG) Center, Washington University in St Louis, St Louis, MO, USA
- Department of Pathology and Immunology, School of Medicine, Washington University in St Louis, St Louis, MO, USA
| | - Jonathan Kipnis
- Brain Immunology and Glia (BIG) Center, Washington University in St Louis, St Louis, MO, USA.
- Department of Pathology and Immunology, School of Medicine, Washington University in St Louis, St Louis, MO, USA.
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4
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Yaghoobi Z, Seyed Bagher Nazeri SS, Asadi A, Derafsh E, Talebi Taheri A, Tamtaji Z, Dadgostar E, Rahmati-Dehkordi F, Aschner M, Mirzaei H, Tamtaji OR, Nabavizadeh F. Non-coding RNAs and Aquaporin 4: Their Role in the Pathogenesis of Neurological Disorders. Neurochem Res 2024; 49:583-596. [PMID: 38114727 DOI: 10.1007/s11064-023-04067-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/10/2023] [Accepted: 11/14/2023] [Indexed: 12/21/2023]
Abstract
Neurological disorders are a major group of non-communicable diseases affecting quality of life. Non-Coding RNAs (ncRNAs) have an important role in the etiology of neurological disorders. In studies on the genesis of neurological diseases, aquaporin 4 (AQP4) expression and activity have both been linked to ncRNAs. The upregulation or downregulation of several ncRNAs leads to neurological disorder progression by targeting AQP4. The role of ncRNAs and AQP4 in neurological disorders is discussed in this review.
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Affiliation(s)
- Zahra Yaghoobi
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran
| | | | - Amir Asadi
- Psychiatry and Behavioral Sciences Research Center, School of Medicine, Addiction Institute, and Department of Psychiatry, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ehsan Derafsh
- Windsor University School of Medicine, Cayon, St Kitts and Nevis
| | - Abdolkarim Talebi Taheri
- Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zeinab Tamtaji
- Student Research Committee, Kashan University of Medical Sciences, Kashan, I.R. of Iran
| | - Ehsan Dadgostar
- Behavioral Sciences Research Center, Isfahan University of Medical Sciences, Isfahan, I.R. of Iran
- Student Research Committee, Isfahan University of Medical Sciences, Isfahan, I.R. of Iran
| | - Fatemeh Rahmati-Dehkordi
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, I.R. of Iran.
| | - Omid Reza Tamtaji
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
| | - Fatemeh Nabavizadeh
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
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5
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Alghanimy A, Work LM, Holmes WM. The glymphatic system and multiple sclerosis: An evolving connection. Mult Scler Relat Disord 2024; 83:105456. [PMID: 38266608 DOI: 10.1016/j.msard.2024.105456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 01/18/2024] [Indexed: 01/26/2024]
Abstract
Multiple sclerosis (MS) is a complex autoimmune disorder that affects the central nervous system, resulting in demyelination and an array of neurological manifestations. Recently, there has been significant scientific interest in the glymphatic system, which operates as a waste-clearance system for the brain. This article reviews the existing literature, and explores potential links between the glymphatic system and MS, shedding light on its evolving significance in the context of MS pathogenesis. The authors consider the pathophysiological implications of glymphatic dysfunction in MS, the impact of disrupted sleep on glymphatic function, and the bidirectional relationship between MS and sleep disturbances. By offering an understanding of the intricate interplay between the glymphatic system and MS, this review provides valuable insights which may lead to improved diagnostic techniques and more effective therapeutic interventions.
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Affiliation(s)
- Alaa Alghanimy
- School of Psychology and Neuroscience, College of Medicine, Veterinary and Life Science, University of Glasgow, Glasgow G61 1QH, United Kingdom; Radiological Sciences Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
| | - Lorraine M Work
- School of Cardiovascular and Metabolic Health, College of Medicine, Veterinary and Life Science, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - William M Holmes
- School of Psychology and Neuroscience, College of Medicine, Veterinary and Life Science, University of Glasgow, Glasgow G61 1QH, United Kingdom
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6
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Freund W, Weber F. The Function of Sleep and the Treatment of Primary Insomnia. DEUTSCHES ARZTEBLATT INTERNATIONAL 2023; 120:863-870. [PMID: 37942822 PMCID: PMC10840130 DOI: 10.3238/arztebl.m2023.0228] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 10/16/2023] [Accepted: 10/16/2023] [Indexed: 11/10/2023]
Abstract
BACKGROUND Approximately 21 900 women and 35 300 men developed lung cancer in Germany in 2018, and 16 999 women and 27 882 men died of it. The outcome mainly depends on the tumor stage. In early stages (stage I or II), treatment can be curative; unfortunately, because early-stage lung cancers are generally asymptom - atic, 74% of women and 77% of men already have advanced-stage disease (stage III or IV) at the time of diagnosis. Screening with low-dose computed tomography is an option enabling early diagnosis and curative treatment. METHODS This review is based on pertinent articles retrieved by a selective search of the literature on screening for lung cancer. RESULTS In the studies of lung cancer screening that have been published to date, sensitivity ranged from 68.5% to 93.8%, and specificity from 73.4% to 99.2%. A meta-analysis by the German Federal Office for Radiation Protection revealed a 15% reduction in lung cancer mortality when low-dose computed tomography was used in persons who were judged to be at high risk for lung cancer (risk ratio [RR] 0.85, 95% confidence interval [0.77; 0.95]). 1.9% of subjects died in the screening arm of the meta-analysis, and 2.2% in the control group. The observation periods ranged from 6.6 to 10 years; false-positive rates ranged from 84.9% to 96.4%. Malignant findings were confirmed in 45% to 70% of the biopsies or resective procedures that were performed. CONCLUSION Systematic lung cancer screening with low-dose CT lowers mortality from lung cancer in (current or former) heavy smokers. This benefit must be weighed against the high rate of false-positive findings and overdiagnoses.
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Affiliation(s)
- Wolfgang Freund
- Neurocenter Biberach
- Diagnostic and Interventional Radiology, Ulm University Hospital, Ulm
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7
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Wyart C, Carbo-Tano M, Cantaut-Belarif Y, Orts-Del'Immagine A, Böhm UL. Cerebrospinal fluid-contacting neurons: multimodal cells with diverse roles in the CNS. Nat Rev Neurosci 2023; 24:540-556. [PMID: 37558908 DOI: 10.1038/s41583-023-00723-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2023] [Indexed: 08/11/2023]
Abstract
The cerebrospinal fluid (CSF) is a complex solution that circulates around the CNS, and whose composition changes as a function of an animal's physiological state. Ciliated neurons that are bathed in the CSF - and thus referred to as CSF-contacting neurons (CSF-cNs) - are unusual polymodal interoceptive neurons. As chemoreceptors, CSF-cNs respond to variations in pH and osmolarity and to bacterial metabolites in the CSF. Their activation during infections of the CNS results in secretion of compounds to enhance host survival. As mechanosensory neurons, CSF-cNs operate together with an extracellular proteinaceous polymer known as the Reissner fibre to detect compression during spinal curvature. Once activated, CSF-cNs inhibit motor neurons, premotor excitatory neurons and command neurons to enhance movement speed and stabilize posture. At longer timescales, CSF-cNs instruct morphogenesis throughout life via the release of neuropeptides that act over long distances on skeletal muscle. Finally, recent evidence suggests that mouse CSF-cNs may act as neural stem cells in the spinal cord, inspiring new paths of investigation for repair after injury.
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Affiliation(s)
- Claire Wyart
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France.
| | - Martin Carbo-Tano
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France
| | - Yasmine Cantaut-Belarif
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France
| | | | - Urs L Böhm
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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8
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Maroli N. Aquaporin-4 Mediated Aggregation of Alzheimer's Amyloid β-Peptide. ACS Chem Neurosci 2023; 14:2683-2698. [PMID: 37486638 DOI: 10.1021/acschemneuro.3c00233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023] Open
Abstract
Clearance of Alzheimer's amyloid oligomers from the brain is crucial for preventing cell toxicity. Dementia complications arise as a result of apoptosis, which is caused by peptide plaques on the lipid surface of cells. Here, we employed all-atom and coarse-grained molecular dynamics simulations to investigate the aggregation of amyloid peptides at the lipid surface and the role of aquaporin-4 (AQP4) in facilitating peptide clearance from astrocytes. The network of protein-protein interactions through text mining revealed that the expression of AQP4 and amyloid aggregation were strongly correlated. It has also been revealed that the role of aquaporins in the etiology of Alzheimer's disease involves several interconnected proteins and pathways. The nature of aggregation at the surface of the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayer was revealed by the interaction of amyloid oligomers. The membrane-bound pore region of AQP4 interacts with the peptide and slows its aggregation. This interaction maintains the helical content of the peptide while lowering its toxicity at the lipid surface. The hydrophobicity of the peptide also decreased because of these interactions, which may help in the removal of the peptide from astrocytes. Long-term coarse-grained MD simulations demonstrated different features of oligomer aggregation at the surface and strong oligomer attraction to AQP4, which inhibited aggregation. Additionally, the water dynamics of aquaporins demonstrate how the selectivity filter is broken to disrupt water flow. Our findings also provide insight into the physiological alterations in brain tissue associated with Alzheimer's disease, including water retention and increased water flow in the CSF. Furthermore, in vitro thioflavin fluorescence spectroscopy revealed a slower aggregation of the peptide in the presence of AQP4.
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Affiliation(s)
- Nikhil Maroli
- Computational Biology Division, DRDO Center for Life Science, Bharathiar University Campus, Coimbatore 641046, Tamil Nadu, India
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9
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Kim D, Gan Y, Nedergaard M, Kelley DH, Tithof J. Image Analysis Techniques for In Vivo Quantification of Cerebrospinal Fluid Flow. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.20.549937. [PMID: 37546970 PMCID: PMC10401935 DOI: 10.1101/2023.07.20.549937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Over the last decade, there has been a tremendously increased interest in understanding the neurophysiology of cerebrospinal fluid (CSF) flow, which plays a crucial role in clearing metabolic waste from the brain. This growing interest was largely initiated by two significant discoveries: the glymphatic system (a pathway for solute exchange between interstitial fluid deep within the brain and the CSF surrounding the brain) and meningeal lymphatic vessels (lymphatic vessels in the layer of tissue surrounding the brain that drain CSF). These two CSF systems work in unison, and their disruption has been implicated in several neurological disorders including Alzheimer's disease, stoke, and traumatic brain injury. Here, we present experimental techniques for in vivo quantification of CSF flow via direct imaging of fluorescent microspheres injected into the CSF. We discuss detailed image processing methods, including registration and masking of stagnant particles, to improve the quality of measurements. We provide guidance for quantifying CSF flow through particle tracking and offer tips for optimizing the process. Additionally, we describe techniques for measuring changes in arterial diameter, which is an hypothesized CSF pumping mechanism. Finally, we outline how these same techniques can be applied to cervical lymphatic vessels, which collect fluid downstream from meningeal lymphatic vessels. We anticipate that these fluid mechanical techniques will prove valuable for future quantitative studies aimed at understanding mechanisms of CSF transport and disruption, as well as for other complex biophysical systems.
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Affiliation(s)
- Daehyun Kim
- Department of Mechanical Engineering, University of Minnesota, 111 Church St SE, Minneapolis, MN, 55455, United States
| | - Yiming Gan
- Department of Mechanical Engineering, University of Rochester, Hopeman Engineering Bldg, Rochester, NY, 14627, United States
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, United States
| | - Douglas H. Kelley
- Department of Mechanical Engineering, University of Rochester, Hopeman Engineering Bldg, Rochester, NY, 14627, United States
| | - Jeffrey Tithof
- Department of Mechanical Engineering, University of Minnesota, 111 Church St SE, Minneapolis, MN, 55455, United States
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10
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Mehta RI, Carpenter JS, Mehta RI, Haut MW, Wang P, Ranjan M, Najib U, D'Haese PF, Rezai AR. Ultrasound-mediated blood-brain barrier opening uncovers an intracerebral perivenous fluid network in persons with Alzheimer's disease. Fluids Barriers CNS 2023; 20:46. [PMID: 37328855 DOI: 10.1186/s12987-023-00447-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 05/31/2023] [Indexed: 06/18/2023] Open
Abstract
BACKGROUND Focused ultrasound (FUS)-mediated blood-brain barrier (BBB) opening is under investigation as a therapeutic modality for neurodegeneration, yet its effects in humans are incompletely understood. Here, we assessed physiologic responses to FUS administered in multifocal brain sites of persons with Alzheimer's disease (AD). METHODS At a tertiary neuroscience institute, eight participants with AD (mean age 65, 38% F) enrolled in a phase 2 clinical trial underwent three successive targeted BBB opening procedures at 2 week intervals using a 220 kHz FUS transducer in combination with systemically administered microbubbles. In all, 77 treatment sites were evaluated and encompassed hippocampal, frontal, and parietal brain regions. Post-FUS imaging changes, including susceptibility effects and spatiotemporal gadolinium-based contrast agent enhancement patterns, were analyzed using serial 3.0-Tesla MRI. RESULTS Post-FUS MRI revealed expected intraparenchymal contrast extravasation due to BBB opening at all targeted brain sites. Immediately upon BBB opening, hyperconcentration of intravenously-administered contrast tracer was consistently observed around intracerebral veins. Following BBB closure, within 24-48 h of FUS intervention, permeabilization of intraparenchymal veins was observed and persisted for up to one week. Notably, extraparenchymal meningeal venous permeabilization and associated CSF effusions were also elicited and persisted up to 11 days post FUS treatment, prior to complete spontaneous resolution in all participants. Mild susceptibility effects were detected, however no overt intracranial hemorrhage or other serious adverse effects occurred in any participant. CONCLUSIONS FUS-mediated BBB opening is safely and reproducibly achieved in multifocal brain regions of persons with AD. Post-FUS tracer enhancement phenomena suggest the existence of a brain-wide perivenous fluid efflux pathway in humans and demonstrate reactive physiological changes involving these conduit spaces in the delayed, subacute phase following BBB disruption. The delayed reactive venous and perivenous changes are consistent with a dynamic, zonal exudative response to upstream capillary manipulation. Further preclinical and clinical investigations of these FUS-related imaging phenomena and of intracerebral perivenous compartment changes are needed to elucidate physiology of this pathway as well as biological effects of FUS administered with and without adjuvant neurotherapeutics. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT03671889, registered 9/14/2018.
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Affiliation(s)
- Rashi I Mehta
- Department of Neuroradiology, West Virginia University, 1 Medical Center Dr, Morgantown, WV, 26506, USA.
- Department of Neuroscience, West Virginia University, Morgantown, WV, 26506, USA.
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA.
| | - Jeffrey S Carpenter
- Department of Neuroradiology, West Virginia University, 1 Medical Center Dr, Morgantown, WV, 26506, USA
- Department of Neuroscience, West Virginia University, Morgantown, WV, 26506, USA
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA
| | - Rupal I Mehta
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, 60612, USA
- Department of Pathology, Rush University Medical Center, Chicago, IL, 60612, USA
| | - Marc W Haut
- Department of Neuroscience, West Virginia University, Morgantown, WV, 26506, USA
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA
- Department of Behavioral Medicine and Psychiatry, West Virginia University, Morgantown, WV, 26506, USA
- Department of Neurology, West Virginia University, Morgantown, WV, 26506, USA
| | - Peng Wang
- Department of Neuroradiology, West Virginia University, 1 Medical Center Dr, Morgantown, WV, 26506, USA
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA
| | - Manish Ranjan
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA
- Department of Neurosurgery, West Virginia University, Morgantown, WV, 26506, USA
| | - Umer Najib
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA
- Department of Neurology, West Virginia University, Morgantown, WV, 26506, USA
| | | | - Ali R Rezai
- Department of Neuroscience, West Virginia University, Morgantown, WV, 26506, USA
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, 26506, USA
- Department of Neurosurgery, West Virginia University, Morgantown, WV, 26506, USA
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11
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Jia Y, Xu S, Han G, Wang B, Wang Z, Lan C, Zhao P, Gao M, Zhang Y, Jiang W, Qiu B, Liu R, Hsu YC, Sun Y, Liu C, Liu Y, Bai R. Transmembrane water-efflux rate measured by magnetic resonance imaging as a biomarker of the expression of aquaporin-4 in gliomas. Nat Biomed Eng 2023; 7:236-252. [PMID: 36376487 DOI: 10.1038/s41551-022-00960-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 10/10/2022] [Indexed: 11/16/2022]
Abstract
The water-selective channel protein aquaporin-4 (AQP4) contributes to the migration and proliferation of gliomas, and to their resistance to therapy. Here we show, in glioma cell cultures, in subcutaneous and orthotopic gliomas in rats, and in glioma tumours in patients, that transmembrane water-efflux rate is a sensitive biomarker of AQP4 expression and can be measured via conventional dynamic-contrast-enhanced magnetic resonance imaging. Water-efflux rates correlated with stages of glioma proliferation as well as with changes in the heterogeneity of intra-tumoural and inter-tumoural AQP4 in rodent and human gliomas following treatment with temozolomide and with the AQP4 inhibitor TGN020. Regions with low water-efflux rates contained higher fractions of stem-like slow-cycling cells and therapy-resistant cells, suggesting that maps of water-efflux rates could be used to identify gliomas that are resistant to therapies.
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Affiliation(s)
- Yinhang Jia
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Shangchen Xu
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Guangxu Han
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Bao Wang
- Department of Radiology, Qilu Hospital of Shandong University, Jinan, China
| | - Zejun Wang
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Chuanjin Lan
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Peng Zhao
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Meng Gao
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Yi Zhang
- Department of Radiology, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Wenhong Jiang
- Zhejiang University School of Medicine, Hangzhou, China
| | - Biying Qiu
- Zhejiang University School of Medicine, Hangzhou, China
| | - Rui Liu
- Zhejiang University School of Medicine, Hangzhou, China
| | - Yi-Cheng Hsu
- MR Collaboration, Siemens Healthcare, Shanghai, China
| | - Yi Sun
- MR Collaboration, Siemens Healthcare, Shanghai, China
| | - Chong Liu
- MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Yingchao Liu
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China.
- Shandong National Center for Applied Mathematics, Shandong University, Jinan, China.
| | - Ruiliang Bai
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China.
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China.
- MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China.
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12
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Gomolka RS, Hablitz LM, Mestre H, Giannetto M, Du T, Hauglund NL, Xie L, Peng W, Martinez PM, Nedergaard M, Mori Y. Loss of aquaporin-4 results in glymphatic system dysfunction via brain-wide interstitial fluid stagnation. eLife 2023; 12:82232. [PMID: 36757363 PMCID: PMC9995113 DOI: 10.7554/elife.82232] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 02/08/2023] [Indexed: 02/10/2023] Open
Abstract
The glymphatic system is a fluid transport network of cerebrospinal fluid (CSF) entering the brain along arterial perivascular spaces, exchanging with interstitial fluid (ISF), ultimately establishing directional clearance of interstitial solutes. CSF transport is facilitated by the expression of aquaporin-4 (AQP4) water channels on the perivascular endfeet of astrocytes. Mice with genetic deletion of AQP4 (AQP4 KO) exhibit abnormalities in the brain structure and molecular water transport. Yet, no studies have systematically examined how these abnormalities in structure and water transport correlate with glymphatic function. Here, we used high-resolution 3D magnetic resonance (MR) non-contrast cisternography, diffusion-weighted MR imaging (MR-DWI) along with intravoxel-incoherent motion (IVIM) DWI, while evaluating glymphatic function using a standard dynamic contrast-enhanced MR imaging to better understand how water transport and glymphatic function is disrupted after genetic deletion of AQP4. AQP4 KO mice had larger interstitial spaces and total brain volumes resulting in higher water content and reduced CSF space volumes, despite similar CSF production rates and vascular density compared to wildtype mice. The larger interstitial fluid volume likely resulted in increased slow but not fast MR diffusion measures and coincided with reduced glymphatic influx. This markedly altered brain fluid transport in AQP4 KO mice may result from a reduction in glymphatic clearance, leading to enlargement and stagnation of fluid in the interstitial space. Overall, diffusion MR is a useful tool to evaluate glymphatic function and may serve as valuable translational biomarker to study glymphatics in human disease.
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Affiliation(s)
| | - Lauren M Hablitz
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
- Department of Neurology, University of PennsylvaniaPhiladelphiaUnited States
| | - Michael Giannetto
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
| | - Ting Du
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
- School of Pharmacy, China Medical UniversityShenyangChina
| | | | - Lulu Xie
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
| | - Weiguo Peng
- Center for Translational Neuromedicine, University of CopenhagenCopenhagenDenmark
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
| | | | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of CopenhagenCopenhagenDenmark
- Center for Translational Neuromedicine, University of Rochester Medical CenterRochesterUnited States
| | - Yuki Mori
- Center for Translational Neuromedicine, University of CopenhagenCopenhagenDenmark
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13
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Bah TM, Siler DA, Ibrahim AH, Cetas JS, Alkayed NJ. Fluid dynamics in aging-related dementias. Neurobiol Dis 2023; 177:105986. [PMID: 36603747 DOI: 10.1016/j.nbd.2022.105986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/22/2022] [Accepted: 12/31/2022] [Indexed: 01/03/2023] Open
Abstract
Recent human and animal model experimental studies revealed novel pathways for fluid movement, immune cell trafficking and metabolic waste clearance in CNS. These studies raise the intriguing possibility that the newly discovered pathways, including the glymphatic system, lymphatic meningeal vessels and skull-brain communication channels, are impaired in aging and neurovascular and neurodegenerative diseases associated with dementia, including Alzheimer's disease (AD) and AD-related dementia. We provide an overview of the glymphatic and dural meningeal lymphatic systems, review current methods and approaches used to study glymphatic flow in humans and animals, and discuss current evidence and controversies related to its role in CNS flow homeostasis under physiological and pathophysiological conditions. Non-invasive imaging approaches are needed to fully understand the mechanisms and pathways driving fluid movement in CNS and their roles across lifespan including healthy aging and aging-related dementia.
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Affiliation(s)
- Thierno M Bah
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA
| | - Dominic A Siler
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Aseel H Ibrahim
- Department of Neurosurgery, University of Arizona, Tucson, AZ, USA
| | - Justin S Cetas
- Department of Neurosurgery, University of Arizona, Tucson, AZ, USA
| | - Nabil J Alkayed
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA; Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, USA.
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14
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Semyachkina-Glushkovskaya OV, Postnov DE, Khorovodov AP, Navolokin NA, Kurthz JHG. Lymphatic Drainage System of the Brain: a New Player in Neuroscience. J EVOL BIOCHEM PHYS+ 2023. [DOI: 10.1134/s0022093023010015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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15
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Soden PA, Henderson AR, Lee E. A Microfluidic Model of AQP4 Polarization Dynamics and Fluid Transport in the Healthy and Inflamed Human Brain: The First Step Towards Glymphatics-on-a-Chip. Adv Biol (Weinh) 2022; 6:e2200027. [PMID: 35922370 PMCID: PMC9771879 DOI: 10.1002/adbi.202200027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 07/01/2022] [Indexed: 01/28/2023]
Abstract
Dysfunction of the aquaporin-4 (AQP4)-dependent glymphatic waste clearance pathway has recently been implicated in the pathogenesis of several neurodegenerative diseases. However, it is difficult to unravel the causative relationship between glymphatic dysfunction, AQP4 depolarization, protein aggregation, and inflammation in neurodegeneration using animal models alone. There is currently a clear, unmet need for in vitro models of the brain's waterscape, and the first steps towards a bona fide "glymphatics-on-a-chip" are taken in the present study. It is demonstrated that chronic exposure to lipopolysaccharide (LPS), amyloid-β(1-42) oligomers, and an AQP4 inhibitor impairs the drainage of fluid and amyloid-β(1-40) tracer in a gliovascular unit (GVU)-on-a-chip model containing human astrocytes and brain microvascular endothelial cells. The LPS-induced drainage impairment is partially retained following cell lysis, indicating that neuroinflammation induces parallel changes in cell-dependent and matrisome-dependent fluid transport pathways in GVU-on-a-chip. Additionally, AQP4 depolarization is observed following LPS treatment, suggesting that LPS-induced drainage impairments on-chip may be driven in part by changes in AQP4-dependent fluid dynamics.
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Affiliation(s)
- Paul A Soden
- College of Human Ecology, Cornell University, Ithaca, NY, 14853, USA
| | - Aria R Henderson
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Esak Lee
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
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16
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Could dexmedetomidine be repurposed as a glymphatic enhancer? Trends Pharmacol Sci 2022; 43:1030-1040. [PMID: 36280451 DOI: 10.1016/j.tips.2022.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 09/26/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022]
Abstract
Cerebrospinal fluid (CSF) flows through the central nervous system (CNS) via the glymphatic pathway to clear the interstitium of metabolic waste. In preclinical studies, glymphatic fluid flow rate increases with low central noradrenergic tone and slow-wave activity during natural sleep and general anesthesia. By contrast, sleep deprivation reduces glymphatic clearance and leads to intracerebral accumulation of metabolic waste, suggesting an underlying mechanism linking sleep disturbances with neurodegenerative diseases. The selective α2-adrenergic agonist dexmedetomidine is a sedative drug that induces slow waves in the electroencephalogram, suppresses central noradrenergic tone, and preserves glymphatic outflow. As recently developed dexmedetomidine formulations enable self-administration, we suggest that dexmedetomidine could serve as a sedative-hypnotic drug to enhance clearance of harmful waste from the brain of those vulnerable to neurodegeneration.
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17
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Zhao L, Tannenbaum A, Bakker ENTP, Benveniste H. Physiology of Glymphatic Solute Transport and Waste Clearance from the Brain. Physiology (Bethesda) 2022; 37:0. [PMID: 35881783 PMCID: PMC9550574 DOI: 10.1152/physiol.00015.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/12/2022] [Accepted: 07/20/2022] [Indexed: 12/25/2022] Open
Abstract
This review focuses on the physiology of glymphatic solute transport and waste clearance, using evidence from experimental animal models as well as from human studies. Specific topics addressed include the biophysical characteristics of fluid and solute transport in the central nervous system, glymphatic-lymphatic coupling, as well as the role of cerebrospinal fluid movement for brain waste clearance. We also discuss the current understanding of mechanisms underlying increased waste clearance during sleep.
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Affiliation(s)
- Lucy Zhao
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Allen Tannenbaum
- Departments of Computer Science and Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York City, New York
| | - Erik N T P Bakker
- Department of Biomedical Engineering and Physics, Amsterdam UMC, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
- Department of Biomedical Engineering, Yale School of Medicine, New Haven, Connecticut
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18
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Transport in the Brain Extracellular Space: Diffusion, but Which Kind? Int J Mol Sci 2022; 23:ijms232012401. [PMID: 36293258 PMCID: PMC9604357 DOI: 10.3390/ijms232012401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 11/17/2022] Open
Abstract
The mechanisms of transport of substances in the brain parenchyma have been a hot topic in scientific discussion in the past decade. This discussion was triggered by the proposed glymphatic hypothesis, which assumes a directed flow of cerebral fluid within the parenchyma, in contrast to the previous notion that diffusion is the main mechanism. However, when discussing the issue of “diffusion or non-diffusion”, much less attention was given to the question that diffusion itself can have a different character. In our opinion, some of the recently published results do not fit into the traditional understanding of diffusion. In this regard, we outline the relevant new theoretical approaches on transport processes in complex random media such as concepts of diffusive diffusivity and time-dependent homogenization, which expands the understanding of the forms of transport of substances based on diffusion.
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19
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Hornkjøl M, Valnes LM, Ringstad G, Rognes ME, Eide PK, Mardal KA, Vinje V. CSF circulation and dispersion yield rapid clearance from intracranial compartments. Front Bioeng Biotechnol 2022; 10:932469. [PMID: 36172015 PMCID: PMC9510842 DOI: 10.3389/fbioe.2022.932469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
In this paper, we used a computational model to estimate the clearance of a tracer driven by the circulation of cerebrospinal fluid (CSF) produced in the choroid plexus (CP) located within the lateral ventricles. CSF was assumed to exit the subarachnoid space (SAS) via different outflow routes such as the parasagittal dura, cribriform plate, and/or meningeal lymphatics. We also modelled a reverse case where fluid was produced within the spinal canal and absorbed in the choroid plexus in line with observations on certain iNPH patients. No directional interstitial fluid flow was assumed within the brain parenchyma. Tracers were injected into the foramen magnum. The models demonstrate that convection in the subarachnoid space yields rapid clearance from both the SAS and the brain interstitial fluid and can speed up intracranial clearance from years, as would be the case for purely diffusive transport, to days.
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Affiliation(s)
- Martin Hornkjøl
- Department of Mathematics, University of Oslo, Blindern, Norway
- *Correspondence: Martin Hornkjøl,
| | - Lars Magnus Valnes
- Department of Neurosurgery, Oslo University Hospital–Rikshospitalet, Oslo, Norway
| | - Geir Ringstad
- Department of Radiology, Oslo University Hospital, Oslo, Norway
- Department of Geriatrics and Internal Medicine, Sorlandet Hospital, Arendal, Norway
| | - Marie E. Rognes
- Department of Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
- Department of Mathematics, University of Bergen, Bergen, Norway
| | - Per-Kristian Eide
- Department of Neurosurgery, Oslo University Hospital–Rikshospitalet, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Kent-André Mardal
- Department of Mathematics, University of Oslo, Blindern, Norway
- Department of Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
| | - Vegard Vinje
- Department of Numerical Analysis and Scientific Computing, Simula Research Laboratory, Oslo, Norway
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20
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Abstract
We review theoretical and numerical models of the glymphatic system, which circulates cerebrospinal fluid and interstitial fluid around the brain, facilitating solute transport. Models enable hypothesis development and predictions of transport, with clinical applications including drug delivery, stroke, cardiac arrest, and neurodegenerative disorders like Alzheimer’s disease. We sort existing models into broad categories by anatomical function: Perivascular flow, transport in brain parenchyma, interfaces to perivascular spaces, efflux routes, and links to neuronal activity. Needs and opportunities for future work are highlighted wherever possible; new models, expanded models, and novel experiments to inform models could all have tremendous value for advancing the field.
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21
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Lysosomal exocytosis releases pathogenic α-synuclein species from neurons in synucleinopathy models. Nat Commun 2022; 13:4918. [PMID: 35995799 PMCID: PMC9395532 DOI: 10.1038/s41467-022-32625-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Abstract
Considerable evidence supports the release of pathogenic aggregates of the neuronal protein α-Synuclein (αSyn) into the extracellular space. While this release is proposed to instigate the neuron-to-neuron transmission and spread of αSyn pathology in synucleinopathies including Parkinson’s disease, the molecular-cellular mechanism(s) remain unclear. To study this, we generated a new mouse model to specifically immunoisolate neuronal lysosomes, and established a long-term culture model where αSyn aggregates are produced within neurons without the addition of exogenous fibrils. We show that neuronally generated pathogenic species of αSyn accumulate within neuronal lysosomes in mouse brains and primary neurons. We then find that neurons release these pathogenic αSyn species via SNARE-dependent lysosomal exocytosis. The released aggregates are non-membrane enveloped and seeding-competent. Additionally, we find that this release is dependent on neuronal activity and cytosolic Ca2+. These results propose lysosomal exocytosis as a central mechanism for the release of aggregated and degradation-resistant proteins from neurons. Release of α-synuclein aggregates by neurons instigates spread of pathology in synucleinopathies, but the mechanism remains unclear. Here the authors show that neuronally generated α-synuclein aggregates accumulate within neuronal lysosomes and are released via SNARE-dependent lysosomal exocytosis.
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22
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The glymphatic system: implications for drugs for central nervous system diseases. Nat Rev Drug Discov 2022; 21:763-779. [PMID: 35948785 DOI: 10.1038/s41573-022-00500-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2022] [Indexed: 12/14/2022]
Abstract
In the past decade, evidence for a fluid clearance pathway in the central nervous system known as the glymphatic system has grown. According to the glymphatic system concept, cerebrospinal fluid flows directionally through the brain and non-selectively clears the interstitium of metabolic waste. Importantly, the glymphatic system may be modulated by particular drugs such as anaesthetics, as well as by non-pharmacological factors such as sleep, and its dysfunction has been implicated in central nervous system disorders such as Alzheimer disease. Although the glymphatic system is best described in rodents, reports using multiple neuroimaging modalities indicate that a similar transport system exists in the human brain. Here, we overview the evidence for the glymphatic system and its role in disease and discuss opportunities to harness the glymphatic system therapeutically; for example, by improving the effectiveness of intrathecally delivered drugs.
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23
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Proulx ST, Engelhardt B. Central nervous system zoning: How brain barriers establish subdivisions for CNS immune privilege and immune surveillance. J Intern Med 2022; 292:47-67. [PMID: 35184353 PMCID: PMC9314672 DOI: 10.1111/joim.13469] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The central nervous system (CNS) coordinates all our body functions. Neurons in the CNS parenchyma achieve this computational task by high speed communication via electrical and chemical signals and thus rely on a strictly regulated homeostatic environment, which does not tolerate uncontrolled entry of blood components including immune cells. The CNS thus has a unique relationship with the immune system known as CNS immune privilege. Previously ascribed to the presence of blood-brain barriers and the lack of lymphatic vessels in the CNS parenchyma prohibiting, respectively, efferent and afferent connections with the peripheral immune system, it is now appreciated that CNS immune surveillance is ensured by cellular and acellular brain barriers that limit immune cell and mediator accessibility to specific compartments at the borders of the CNS. CNS immune privilege is established by a brain barriers anatomy resembling the architecture of a medieval castle surrounded by two walls bordering a castle moat. Built for protection and defense this two-walled rampart at the outer perimeter of the CNS parenchyma allows for accommodation of different immune cell subsets and efficient monitoring of potential danger signals derived from inside or outside of the CNS parenchyma. It enables effective mounting of immune responses within the subarachnoid or perivascular spaces, while leaving the CNS parenchyma relatively undisturbed. In this study, we propose that CNS immune privilege rests on the proper function of the brain barriers, which allow for CNS immune surveillance but prohibit activation of immune responses from the CNS parenchyma unless it is directly injured.
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Affiliation(s)
- Steven T Proulx
- Theodor Kocher Institute, University of Bern, Bern, Switzerland
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24
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Xuan X, Zhou G, Chen C, Shao A, Zhou Y, Li X, Zhou J. Glymphatic System: Emerging Therapeutic Target for Neurological Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:6189170. [PMID: 35726332 PMCID: PMC9206554 DOI: 10.1155/2022/6189170] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/15/2022] [Accepted: 05/24/2022] [Indexed: 11/17/2022]
Abstract
The newly discovered glymphatic system acts as pseudolymphatic vessels subserving brain waste clearance and is functionally dependent on astrocytic aquaporin-4 channels. The glymphatic system primarily functions during sleep as an interchange between cerebrospinal fluid and interstitial fluid, with cerebrospinal fluid flowing into the parenchyma via the perivascular spaces and then exchanging with interstitial fluid. The discovery of meningeal lymphatics helps refine the conceptual framework of glymphatic pathway, as certain waste products collected alongside perivascular spaces ultimately drain into the cervical lymph nodes via meningeal lymphatics, whose function regulates the functioning of the glymphatic system. The glymphatic and meningeal lymphatic systems are critical for the homeostasis of central nervous system, and their malfunctions complicate cerebral dysfunction and diseases. The present review will shed light on the structure, regulation, functions, and interrelationships of the glymphatic system and meningeal lymphatics. We will also expound on their impairments and corresponding targeted intervention in neurodegenerative diseases, traumatic brain injury, stroke, and infectious/autoimmune diseases, offering valuable references for future research.
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Affiliation(s)
- Xianjun Xuan
- Department of Neurology, Hangzhou Ninth People's Hospital, Hangzhou, China
| | - Guoyi Zhou
- The Fourth School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Caihong Chen
- Department of Neurology, Hangzhou Ninth People's Hospital, Hangzhou, China
| | - Anwen Shao
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yunxiang Zhou
- Department of Surgical Oncology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaobo Li
- Department of Neurology, Hangzhou Ninth People's Hospital, Hangzhou, China
| | - Jiaqi Zhou
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, China
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25
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Szu JI, Binder DK. Mechanisms Underlying Aquaporin-4 Subcellular Mislocalization in Epilepsy. Front Cell Neurosci 2022; 16:900588. [PMID: 35734218 PMCID: PMC9207308 DOI: 10.3389/fncel.2022.900588] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
Epilepsy is a chronic brain disorder characterized by unprovoked seizures. Mechanisms underlying seizure activity have been intensely investigated. Alterations in astrocytic channels and transporters have shown to be a critical player in seizure generation and epileptogenesis. One key protein involved in such processes is the astrocyte water channel aquaporin-4 (AQP4). Studies have revealed that perivascular AQP4 redistributes away from astrocyte endfeet and toward the neuropil in both clinical and preclinical studies. This subcellular mislocalization significantly impacts neuronal hyperexcitability and understanding how AQP4 becomes dysregulated in epilepsy is beginning to emerge. In this review, we evaluate the role of AQP4 dysregulation and mislocalization in epilepsy.
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26
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Abstract
The brain harbors a unique ability to, figuratively speaking, shift its gears. During wakefulness, the brain is geared fully toward processing information and behaving, while homeostatic functions predominate during sleep. The blood-brain barrier establishes a stable environment that is optimal for neuronal function, yet the barrier imposes a physiological problem; transcapillary filtration that forms extracellular fluid in other organs is reduced to a minimum in brain. Consequently, the brain depends on a special fluid [the cerebrospinal fluid (CSF)] that is flushed into brain along the unique perivascular spaces created by astrocytic vascular endfeet. We describe this pathway, coined the term glymphatic system, based on its dependency on astrocytic vascular endfeet and their adluminal expression of aquaporin-4 water channels facing toward CSF-filled perivascular spaces. Glymphatic clearance of potentially harmful metabolic or protein waste products, such as amyloid-β, is primarily active during sleep, when its physiological drivers, the cardiac cycle, respiration, and slow vasomotion, together efficiently propel CSF inflow along periarterial spaces. The brain's extracellular space contains an abundance of proteoglycans and hyaluronan, which provide a low-resistance hydraulic conduit that rapidly can expand and shrink during the sleep-wake cycle. We describe this unique fluid system of the brain, which meets the brain's requisites to maintain homeostasis similar to peripheral organs, considering the blood-brain-barrier and the paths for formation and egress of the CSF.
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Affiliation(s)
- Martin Kaag Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
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Perivascular pumping in the mouse brain: Improved boundary conditions reconcile theory, simulation, and experiment. J Theor Biol 2022; 542:111103. [PMID: 35339513 DOI: 10.1016/j.jtbi.2022.111103] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 02/16/2022] [Accepted: 03/17/2022] [Indexed: 01/24/2023]
Abstract
Cerebrospinal fluid (CSF) flows through the perivascular spaces (PVSs) surrounding cerebral arteries. Revealing the mechanisms driving that flow could bring improved understanding of brain waste transport and insights for disorders including Alzheimer's disease and stroke. In vivo velocity measurements of CSF in surface PVSs in mice have been used to argue that flow is driven primarily by the pulsatile motion of artery walls - perivascular pumping. However, fluid dynamics theory and simulation have predicted that perivascular pumping produces flows differing from in vivo observations starkly, particularly in the phase and relative amplitude of flow oscillation. We show that coupling theoretical and simulated flows to more realistic end boundary conditions, using resistance and compliance values measured in mice instead of using periodic boundaries, results in velocities that match observations more closely in phase and relative amplitude of oscillation, while preserving the existing agreement in mean flow speed. This quantitative agreement among theory, simulation, and in vivo measurement further supports the idea that perivascular pumping is an important CSF driver in physiological conditions.
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Sunkaria A, Bhardwaj S. Sleep Disturbance and Alzheimer's Disease: The Glial Connection. Neurochem Res 2022; 47:1799-1815. [PMID: 35303225 DOI: 10.1007/s11064-022-03578-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/27/2022] [Accepted: 03/09/2022] [Indexed: 12/28/2022]
Abstract
Poor quality and quantity of sleep are very common in elderly people throughout the world. Growing evidence has suggested that sleep disturbances could accelerate the process of neurodegeneration. Recent reports have shown a positive correlation between sleep deprivation and amyloid-β (Aβ)/tau aggregation in the brain of Alzheimer's patients. Glial cells have long been implicated in the progression of Alzheimer's disease (AD) and recent findings have also suggested their role in regulating sleep homeostasis. However, how glial cells control the sleep-wake balance and exactly how disturbed sleep may act as a trigger for Alzheimer's or other neurological disorders have recently gotten attention. In an attempt to connect the dots, the present review has highlighted the role of glia-derived sleep regulatory molecules in AD pathogenesis. Role of glia in sleep disturbance and Alzheimer's progression.
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Affiliation(s)
- Aditya Sunkaria
- Department of Biotechnology, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
| | - Supriya Bhardwaj
- Department of Dermatology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India
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29
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Hladky SB, Barrand MA. The glymphatic hypothesis: the theory and the evidence. Fluids Barriers CNS 2022; 19:9. [PMID: 35115036 PMCID: PMC8815211 DOI: 10.1186/s12987-021-00282-z] [Citation(s) in RCA: 87] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022] Open
Abstract
The glymphatic hypothesis proposes a mechanism for extravascular transport into and out of the brain of hydrophilic solutes unable to cross the blood-brain barrier. It suggests that there is a circulation of fluid carrying solutes inwards via periarterial routes, through the interstitium and outwards via perivenous routes. This review critically analyses the evidence surrounding the mechanisms involved in each of these stages. There is good evidence that both influx and efflux of solutes occur along periarterial routes but no evidence that the principal route of outflow is perivenous. Furthermore, periarterial inflow of fluid is unlikely to be adequate to provide the outflow that would be needed to account for solute efflux. A tenet of the hypothesis is that flow sweeps solutes through the parenchyma. However, the velocity of any possible circulatory flow within the interstitium is too small compared to diffusion to provide effective solute movement. By comparison the earlier classical hypothesis describing extravascular transport proposed fluid entry into the parenchyma across the blood-brain barrier, solute movements within the parenchyma by diffusion, and solute efflux partly by diffusion near brain surfaces and partly carried by flow along "preferred routes" including perivascular spaces, white matter tracts and subependymal spaces. It did not suggest fluid entry via periarterial routes. Evidence is still incomplete concerning the routes and fate of solutes leaving the brain. A large proportion of the solutes eliminated from the parenchyma go to lymph nodes before reaching blood but the proportions delivered directly to lymph or indirectly via CSF which then enters lymph are as yet unclear. In addition, still not understood is why and how the absence of AQP4 which is normally highly expressed on glial endfeet lining periarterial and perivenous routes reduces rates of solute elimination from the parenchyma and of solute delivery to it from remote sites of injection. Neither the glymphatic hypothesis nor the earlier classical hypothesis adequately explain how solutes and fluid move into, through and out of the brain parenchyma. Features of a more complete description are discussed. All aspects of extravascular transport require further study.
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Affiliation(s)
- Stephen B. Hladky
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| | - Margery A. Barrand
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
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Elbert DL, Patterson BW, Lucey BP, Benzinger TLS, Bateman RJ. Importance of CSF-based Aβ clearance with age in humans increases with declining efficacy of blood-brain barrier/proteolytic pathways. Commun Biol 2022; 5:98. [PMID: 35087179 PMCID: PMC8795390 DOI: 10.1038/s42003-022-03037-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 12/27/2021] [Indexed: 12/21/2022] Open
Abstract
The kinetics of amyloid beta turnover within human brain is still poorly understood. We previously found a dramatic decline in the turnover of Aβ peptides in normal aging. It was not known if brain interstitial fluid/cerebrospinal fluid (ISF/CSF) fluid exchange, CSF turnover, blood-brain barrier function or proteolysis were affected by aging or the presence of β amyloid plaques. Here, we describe a non-steady state physiological model developed to decouple CSF fluid transport from other processes. Kinetic parameters were estimated using: (1) MRI-derived brain volumes, (2) stable isotope labeling kinetics (SILK) of amyloid-β peptide (Aβ), and (3) lumbar CSF Aβ concentration during SILK. Here we show that changes in blood-brain barrier transport and/or proteolysis were largely responsible for the age-related decline in Aβ turnover rates. CSF-based clearance declined modestly in normal aging but became increasingly important due to the slowing of other processes. The magnitude of CSF-based clearance was also lower than that due to blood-brain barrier function plus proteolysis. These results suggest important roles for blood-brain barrier transport and proteolytic degradation of Aβ in the development Alzheimer’s Disease in humans. To understand if brain interstitial fluid/cerebrospinal fluid (ISF/CSF) exchange, CSF turnover, blood-brain barrier function or proteolysis were affected by aging or the presence of β amyloid plaques, Elbert et al. develop a non-steady state physiological model using MRI-derived brain volumes, stable isotope labeling kinetics of Aβ, and lumbar CSF Aβ concentration. Their model suggests an important role for blood-brain barrier transport and proteolytic degradation of Aβ in the development Alzheimer’s Disease in humans.
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Affiliation(s)
- Donald L Elbert
- Department of Neurology, Dell Medical School, University of Texas at Austin, Austin, TX, USA.
| | - Bruce W Patterson
- Department of Medicine, Washington University in St. Louis, St. Louis, MO, USA
| | - Brendan P Lucey
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO, USA
| | - Tammie L S Benzinger
- Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO, USA.,Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Randall J Bateman
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO, USA
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31
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Yim Y, Moon WJ. An Enlarged Perivascular Space: Clinical Relevance and the Role of Imaging in Aging and Neurologic Disorders. JOURNAL OF THE KOREAN SOCIETY OF RADIOLOGY 2022; 83:538-558. [PMID: 36238506 PMCID: PMC9514531 DOI: 10.3348/jksr.2022.0049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 04/28/2022] [Accepted: 05/05/2022] [Indexed: 11/15/2022]
Affiliation(s)
- Younghee Yim
- Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea
| | - Won-Jin Moon
- Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea
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32
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Ray LA, Pike M, Simon M, Iliff JJ, Heys JJ. Quantitative analysis of macroscopic solute transport in the murine brain. Fluids Barriers CNS 2021; 18:55. [PMID: 34876169 PMCID: PMC8650464 DOI: 10.1186/s12987-021-00290-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/21/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Understanding molecular transport in the brain is critical to care and prevention of neurological disease and injury. A key question is whether transport occurs primarily by diffusion, or also by convection or dispersion. Dynamic contrast-enhanced (DCE-MRI) experiments have long reported solute transport in the brain that appears to be faster than diffusion alone, but this transport rate has not been quantified to a physically relevant value that can be compared to known diffusive rates of tracers. METHODS In this work, DCE-MRI experimental data is analyzed using subject-specific finite-element models to quantify transport in different anatomical regions across the whole mouse brain. The set of regional effective diffusivities ([Formula: see text]), a transport parameter combining all mechanisms of transport, that best represent the experimental data are determined and compared to apparent diffusivity ([Formula: see text]), the known rate of diffusion through brain tissue, to draw conclusions about dominant transport mechanisms in each region. RESULTS In the perivascular regions of major arteries, [Formula: see text] for gadoteridol (550 Da) was over 10,000 times greater than [Formula: see text]. In the brain tissue, constituting interstitial space and the perivascular space of smaller blood vessels, [Formula: see text] was 10-25 times greater than [Formula: see text]. CONCLUSIONS The analysis concludes that convection is present throughout the brain. Convection is dominant in the perivascular space of major surface and branching arteries (Pe > 1000) and significant to large molecules (> 1 kDa) in the combined interstitial space and perivascular space of smaller vessels (not resolved by DCE-MRI). Importantly, this work supports perivascular convection along penetrating blood vessels.
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Affiliation(s)
- Lori A Ray
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, USA
| | - Martin Pike
- Advanced Imaging Research Center, Oregon Health and Sciences University, Portland, USA
| | - Matthew Simon
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, USA
- Neuroscience Graduate Program, Oregon Health and Science University, Portland, USA
- Denali Therapeutics, San Francisco, USA
| | - Jeffrey J Iliff
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, Seattle, USA
- Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, USA
- Department of Neurology, University of Washington School of Medicine, Seattle, USA
| | - Jeffrey J Heys
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, USA.
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Klostranec JM, Vucevic D, Bhatia KD, Kortman HGJ, Krings T, Murphy KP, terBrugge KG, Mikulis DJ. Current Concepts in Intracranial Interstitial Fluid Transport and the Glymphatic System: Part II-Imaging Techniques and Clinical Applications. Radiology 2021; 301:516-532. [PMID: 34698564 DOI: 10.1148/radiol.2021204088] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The glymphatic system is a recently discovered network unique to the central nervous system that allows for dynamic exchange of interstitial fluid (ISF) and cerebrospinal fluid (CSF). As detailed in part I, ISF and CSF transport along paravascular channels of the penetrating arteries and possibly veins allow essential clearance of neurotoxic solutes from the interstitium to the CSF efflux pathways. Imaging tests to investigate this neurophysiologic function, although challenging, are being developed and are reviewed herein. These include direct visualization of CSF transport using postcontrast imaging techniques following intravenous or intrathecal administration of contrast material and indirect glymphatic assessment with detection of enlarged perivascular spaces. Application of MRI techniques, including intravoxel incoherent motion, diffusion tensor imaging, and chemical exchange saturation transfer, is also discussed, as are methods for imaging dural lymphatic channels involved with CSF efflux. Subsequently, glymphatic function is considered in the context of proteinopathies associated with neurodegenerative diseases and traumatic brain injury, cytotoxic edema following acute ischemic stroke, and chronic hydrocephalus after subarachnoid hemorrhage. These examples highlight the substantial role of the glymphatic system in neurophysiology and the development of certain neuropathologic abnormalities, stressing the importance of its consideration when interpreting neuroimaging investigations. © RSNA, 2021.
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Affiliation(s)
- Jesse M Klostranec
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - Diana Vucevic
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - Kartik D Bhatia
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - Hans G J Kortman
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - Timo Krings
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - Kieran P Murphy
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - Karel G terBrugge
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
| | - David J Mikulis
- From the Department of Diagnostic and Interventional Neuroradiology, Montréal Neurologic Institute and Hospital, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.), Department of Materials Science & Engineering, Faculty of Applied Science & Engineering (D.V.), and Division of Neurosurgery, Department of Surgery (T.K., K.G.t.B.), University of Toronto, Toronto, Canada; Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montréal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montréal, Montréal, Canada (J.M.K.); and Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.)
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Ouellette J, Lacoste B. From Neurodevelopmental to Neurodegenerative Disorders: The Vascular Continuum. Front Aging Neurosci 2021; 13:749026. [PMID: 34744690 PMCID: PMC8570842 DOI: 10.3389/fnagi.2021.749026] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Structural and functional integrity of the cerebral vasculature ensures proper brain development and function, as well as healthy aging. The inability of the brain to store energy makes it exceptionally dependent on an adequate supply of oxygen and nutrients from the blood stream for matching colossal demands of neural and glial cells. Key vascular features including a dense vasculature, a tightly controlled environment, and the regulation of cerebral blood flow (CBF) all take part in brain health throughout life. As such, healthy brain development and aging are both ensured by the anatomical and functional interaction between the vascular and nervous systems that are established during brain development and maintained throughout the lifespan. During critical periods of brain development, vascular networks remodel until they can actively respond to increases in neural activity through neurovascular coupling, which makes the brain particularly vulnerable to neurovascular alterations. The brain vasculature has been strongly associated with the onset and/or progression of conditions associated with aging, and more recently with neurodevelopmental disorders. Our understanding of cerebrovascular contributions to neurological disorders is rapidly evolving, and increasing evidence shows that deficits in angiogenesis, CBF and the blood-brain barrier (BBB) are causally linked to cognitive impairment. Moreover, it is of utmost curiosity that although neurodevelopmental and neurodegenerative disorders express different clinical features at different stages of life, they share similar vascular abnormalities. In this review, we present an overview of vascular dysfunctions associated with neurodevelopmental (autism spectrum disorders, schizophrenia, Down Syndrome) and neurodegenerative (multiple sclerosis, Huntington's, Parkinson's, and Alzheimer's diseases) disorders, with a focus on impairments in angiogenesis, CBF and the BBB. Finally, we discuss the impact of early vascular impairments on the expression of neurodegenerative diseases.
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Affiliation(s)
- Julie Ouellette
- Ottawa Hospital Research Institute, Neuroscience Program, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Baptiste Lacoste
- Ottawa Hospital Research Institute, Neuroscience Program, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
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35
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Klostranec JM, Vucevic D, Bhatia KD, Kortman HGJ, Krings T, Murphy KP, terBrugge KG, Mikulis DJ. Current Concepts in Intracranial Interstitial Fluid Transport and the Glymphatic System: Part I-Anatomy and Physiology. Radiology 2021; 301:502-514. [PMID: 34665028 DOI: 10.1148/radiol.2021202043] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Normal physiologic function of organs requires a circulation of interstitial fluid to deliver nutrients and clear cellular waste products. Lymphatic vessels serve as collectors of this fluid in most organs; however, these vessels are absent in the central nervous system. How the central nervous system maintains tight control of extracellular conditions has been a fundamental question in neuroscience until recent discovery of the glial-lymphatic, or glymphatic, system was made this past decade. Networks of paravascular channels surrounding pial and parenchymal arteries and veins were found that extend into the walls of capillaries to allow fluid transport and exchange between the interstitial and cerebrospinal fluid spaces. The currently understood anatomy and physiology of the glymphatic system is reviewed, with the paravascular space presented as an intrinsic component of healthy pial and parenchymal cerebral blood vessels. Glymphatic system behavior in animal models of health and disease, and its enhanced function during sleep, are discussed. The evolving understanding of glymphatic system characteristics is then used to provide a current interpretation of its physiology that can be helpful for radiologists when interpreting neuroimaging investigations.
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Affiliation(s)
- Jesse M Klostranec
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Diana Vucevic
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Kartik D Bhatia
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Hans G J Kortman
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Timo Krings
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Kieran P Murphy
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - Karel G terBrugge
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
| | - David J Mikulis
- From the Montreal Neurologic Institute and Hospital, Department of Diagnostic and Interventional Neuroradiology, McGill University Health Centre, 3801 Rue University, Montréal, QC, Canada H3A 2B4 (J.M.K.); Department of Medical Imaging, University of Toronto, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Division of Neuroradiology, Toronto Western Hospital, University Health Network, Toronto, Canada (J.M.K., D.V., K.D.B., H.G.J.K., T.K., K.P.M., K.G.t.B., D.J.M.); Centre Hospitalier de l'Université de Montreal (CHUM), Department of Radiology, Service of Neuroradiology, l'Université de Montreal, Montréal, Canada (J.M.K.); Department of Materials Science & Engineering, Faculty of Applied Science & Engineering, University of Toronto, Toronto, Canada (D.V.); Department of Medical Imaging, Sydney Children's Hospitals Network, Westmead, Australia (K.D.B.); and Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada (T.K., K.G.t.B.)
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36
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MacAulay N. Reply to 'Aquaporin 4 and glymphatic flow have central roles in brain fluid homeostasis'. Nat Rev Neurosci 2021; 22:651-652. [PMID: 34408335 DOI: 10.1038/s41583-021-00515-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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37
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Eide PK, Vinje V, Pripp AH, Mardal KA, Ringstad G. Sleep deprivation impairs molecular clearance from the human brain. Brain 2021; 144:863-874. [PMID: 33829232 DOI: 10.1093/brain/awaa443] [Citation(s) in RCA: 129] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/24/2020] [Accepted: 10/08/2020] [Indexed: 01/02/2023] Open
Abstract
It remains an enigma why human beings spend one-third of their life asleep. Experimental data suggest that sleep is required for clearance of waste products from brain metabolism. This has, however, never been verified in humans. The primary aim of the present study was to examine in vivo whether one night of total sleep deprivation affects molecular clearance from the human brain. Secondarily, we examined whether clearance was affected by subsequent sleep. Multiphase MRI with standardized T1 sequences was performed up to 48 h after intrathecal administration of the contrast agent gadobutrol (0.5 ml of 1 mmol/ml), which served as a tracer molecule. Using FreeSurfer software, we quantified tracer enrichment within 85 brain regions as percentage change from baseline of normalized T1 signals. The cerebral tracer enrichment was compared between two cohorts of individuals; one cohort (n = 7) underwent total sleep deprivation from Day 1 to Day 2 (sleep deprivation group) while an age and gender-matched control group (n = 17; sleep group) was allowed free sleep from Day 1 to Day 2. From Day 2 to 3 all individuals were allowed free sleep. The tracer enriched the brains of the two groups similarly. Sleep deprivation was the sole intervention. One night of sleep deprivation impaired clearance of the tracer substance from most brain regions, including the cerebral cortex, white matter and limbic structures, as demonstrated on the morning of Day 2 after intervention (sleep deprivation/sleep). Moreover, the impaired cerebral clearance in the sleep deprivation group was not compensated by subsequent sleep from Day 2 to 3. The present results provide in vivo evidence that one night of total sleep deprivation impairs molecular clearance from the human brain, and that humans do not catch up on lost sleep.
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Affiliation(s)
- Per Kristian Eide
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Neurosurgery, Oslo University Hospital - Rikshospitalet, Oslo, Norway
| | - Vegard Vinje
- Center for Biomedical Computing, Simula Research Laboratory, Lysaker, Norway
| | - Are Hugo Pripp
- Oslo Centre of Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital, Oslo, Norway
| | - Kent-Andre Mardal
- Center for Biomedical Computing, Simula Research Laboratory, Lysaker, Norway.,Department of Mathematics, University of Oslo, Oslo, Norway
| | - Geir Ringstad
- Department of Radiology, Oslo University Hospital - Rikshospitalet, Oslo, Norway
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38
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Che Mohd Nassir CMN, Damodaran T, Yusof SR, Norazit A, Chilla G, Huen I, K. N. BP, Mohamed Ibrahim N, Mustapha M. Aberrant Neurogliovascular Unit Dynamics in Cerebral Small Vessel Disease: A Rheological Clue to Vascular Parkinsonism. Pharmaceutics 2021; 13:1207. [PMID: 34452169 PMCID: PMC8398765 DOI: 10.3390/pharmaceutics13081207] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/29/2021] [Accepted: 08/03/2021] [Indexed: 12/26/2022] Open
Abstract
The distinctive anatomical assemble and functionally discrete multicellular cerebrovasculature dynamics confer varying rheological and blood-brain barrier permeabilities to preserve the integrity of cerebral white matter and its neural microenvironment. This homeostasis intricately involves the glymphatic system that manages the flow of interstitial solutes, metabolic waste, and clearance through the venous circulation. As a physiologically integrated neurogliovascular unit (NGVU) serving a particularly vulnerable cerebral white matter (from hypoxia, metabolic insults, infection, and inflammation), a likely insidious process over a lifetime could inflict microenvironment damages that may lead to pathological conditions. Two such conditions, cerebral small vessel disease (CSVD) and vascular parkinsonism (VaP), with poorly understood pathomechanisms, are frequently linked to this brain-wide NGVU. VaP is widely regarded as an atypical parkinsonism, described by cardinal motor manifestations and the presence of cerebrovascular disease, particularly white matter hyperintensities (WMHs) in the basal ganglia and subcortical region. WMHs, in turn, are a recognised imaging spectrum of CSVD manifestations, and in relation to disrupted NGVU, also include enlarged perivascular spaces. Here, in this narrative review, we present and discuss on recent findings that argue for plausible clues between CSVD and VaP by focusing on aberrant multicellular dynamics of a unique integrated NGVU-a crossroad of the immune-vascular-nervous system-which may also extend fresher insights into the elusive interplay between cerebral microvasculature and neurodegeneration, and the potential therapeutic targets.
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Affiliation(s)
- Che Mohd Nasril Che Mohd Nassir
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan, Malaysia;
| | - Thenmoly Damodaran
- Centre for Drug Research, Universiti Sains Malaysia, Minden 11800, Penang, Malaysia; (T.D.); (S.R.Y.)
| | - Siti R. Yusof
- Centre for Drug Research, Universiti Sains Malaysia, Minden 11800, Penang, Malaysia; (T.D.); (S.R.Y.)
| | - Anwar Norazit
- Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Selangor, Malaysia;
| | - Geetha Chilla
- A*STAR Institute of Bioengineering and Bioimaging, Helios, 11 Biopolis Way, Singapore 138667, Singapore; (G.C.); (I.H.); (B.P.K.N.)
| | - Isaac Huen
- A*STAR Institute of Bioengineering and Bioimaging, Helios, 11 Biopolis Way, Singapore 138667, Singapore; (G.C.); (I.H.); (B.P.K.N.)
| | - Bhanu Prakash K. N.
- A*STAR Institute of Bioengineering and Bioimaging, Helios, 11 Biopolis Way, Singapore 138667, Singapore; (G.C.); (I.H.); (B.P.K.N.)
| | - Norlinah Mohamed Ibrahim
- Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Selangor, Malaysia;
| | - Muzaimi Mustapha
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan, Malaysia;
- Hospital Universiti Sains Malaysia, Jalan Raja Perempuan Zainab II, Kubang Kerian 16150, Kelantan, Malaysia
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39
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Smith AJ, Akdemir G, Wadhwa M, Song D, Verkman AS. Application of fluorescent dextrans to the brain surface under constant pressure reveals AQP4-independent solute uptake. J Gen Physiol 2021; 153:212385. [PMID: 34128962 PMCID: PMC8210582 DOI: 10.1085/jgp.202112898] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/11/2021] [Indexed: 12/26/2022] Open
Abstract
Extracellular solutes in the central nervous system are exchanged between the interstitial fluid, the perivascular compartment, and the cerebrospinal fluid (CSF). The "glymphatic" mechanism proposes that the astrocyte water channel aquaporin-4 (AQP4) is a major determinant of solute transport between the CSF and the interstitial space; however, this is controversial in part because of wide variance in experimental data on interstitial uptake of cisternally injected solutes. Here, we investigated the determinants of solute uptake in brain parenchyma following cisternal injection and reexamined the role of AQP4 using a novel constant-pressure method. In mice, increased cisternal injection rate, which modestly increased intracranial pressure, remarkably increased solute dispersion in the subarachnoid space and uptake in the cortical perivascular compartment. To investigate the role of AQP4 in the absence of confounding variations in pressure and CSF solute concentration over time and space, solutes were applied directly onto the brain surface after durotomy under constant external pressure. Pressure elevation increased solute penetration into the perivascular compartment but had little effect on parenchymal solute uptake. Solute penetration and uptake did not differ significantly between wild-type and AQP4 knockout mice. Our results offer an explanation for the variability in cisternal injection studies and indicate AQP4-independent solute transfer from the CSF to the interstitial space in mouse brain.
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Affiliation(s)
- Alex J Smith
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA.,Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA
| | - Gokhan Akdemir
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA
| | - Meetu Wadhwa
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA
| | - Dan Song
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA
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40
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Lv T, Zhao B, Hu Q, Zhang X. The Glymphatic System: A Novel Therapeutic Target for Stroke Treatment. Front Aging Neurosci 2021; 13:689098. [PMID: 34305569 PMCID: PMC8297504 DOI: 10.3389/fnagi.2021.689098] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/07/2021] [Indexed: 12/25/2022] Open
Abstract
The glymphatic system (GS) is a novel defined brain-wide perivascular transit network between cerebrospinal fluid (CSF) and interstitial solutes that facilitates the clearance of brain metabolic wastes. The complicated network of the GS consists of the periarterial CSF influx pathway, astrocytes-mediated convective transport of fluid and solutes supported by AQP4 water channels, and perivenous efflux pathway. Recent researches indicate that the GS dysfunction is associated with various neurological disorders, including traumatic brain injury, hydrocephalus, epilepsy, migraine, and Alzheimer’s disease (AD). Meanwhile, the GS also plays a pivotal role in the pathophysiological process of stroke, including brain edema, blood–brain barrier (BBB) disruption, immune cell infiltration, neuroinflammation, and neuronal apoptosis. In this review, we illustrated the key anatomical structures of the GS, the relationship between the GS and the meningeal lymphatic system, the interaction between the GS and the BBB, and the crosstalk between astrocytes and other GS cellular components. In addition, we contributed to the current knowledge about the role of the GS in the pathology of stroke and the role of AQP4 in stroke. We further discussed the potential use of the GS in early risk assessment, diagnostics, prognostics, and therapeutics of stroke.
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Affiliation(s)
- Tao Lv
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Bing Zhao
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qin Hu
- Central Laboratory, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaohua Zhang
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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41
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Kaur J, Fahmy LM, Davoodi-Bojd E, Zhang L, Ding G, Hu J, Zhang Z, Chopp M, Jiang Q. Waste Clearance in the Brain. Front Neuroanat 2021; 15:665803. [PMID: 34305538 PMCID: PMC8292771 DOI: 10.3389/fnana.2021.665803] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 06/15/2021] [Indexed: 12/15/2022] Open
Abstract
Waste clearance (WC) is an essential process for brain homeostasis, which is required for the proper and healthy functioning of all cerebrovascular and parenchymal brain cells. This review features our current understanding of brain WC, both within and external to the brain parenchyma. We describe the interplay of the blood-brain barrier (BBB), interstitial fluid (ISF), and perivascular spaces within the brain parenchyma for brain WC directly into the blood and/or cerebrospinal fluid (CSF). We also discuss the relevant role of the CSF and its exit routes in mediating WC. Recent discoveries of the glymphatic system and meningeal lymphatic vessels, and their relevance to brain WC are highlighted. Controversies related to brain WC research and potential future directions are presented.
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Affiliation(s)
- Jasleen Kaur
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
- Department of Physics, Oakland University, Rochester, MI, United States
| | - Lara M. Fahmy
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI, United States
| | - Esmaeil Davoodi-Bojd
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
- Department of Radiology, Henry Ford Health System, Detroit, MI, United States
| | - Li Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
| | - Guangliang Ding
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
| | - Jiani Hu
- Department of Radiology, Wayne State University, Detroit, MI, United States
| | - Zhenggang Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
- Department of Neurology, Wayne State University, Detroit, MI, United States
| | - Michael Chopp
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
- Department of Physics, Oakland University, Rochester, MI, United States
| | - Quan Jiang
- Department of Neurology, Henry Ford Health System, Detroit, MI, United States
- Department of Physics, Oakland University, Rochester, MI, United States
- Department of Neurology, Wayne State University, Detroit, MI, United States
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42
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Abstract
Cerebrospinal fluid flows around and into the brain, driven by intricate mechanisms, with profound implications for human health. According to the glymphatic hypothesis, in physiological conditions, cerebrospinal fluid flows primarily during sleep and serves to remove metabolic wastes like the amyloid-beta and tau proteins whose accumulation is believed to cause Alzheimer's disease. This paper reviews one research team's recent in vivo experiments and theoretical studies to better understand the fluid dynamics of brain cerebrospinal fluid flow. Driving mechanisms are considered, particularly arterial pulsation. Flow correlates closely with artery motion and changes when artery motion is manipulated. Though there are discrepancies between in vivo observations and predictions from simulations and theoretical studies of the mechanism, realistic boundary conditions bring closer agreement. Vessel shapes are considered, and have elongation that minimizes their hydraulic resistance, perhaps through evolutionary optimization. The pathological condition of stroke is considered. Much tissue damage after stroke is caused by swelling, and there is now strong evidence that early swelling is caused not by fluid from blood, as is commonly thought, but by cerebrospinal fluid. Finally, drug delivery is considered, and demonstrations show the glymphatic system could quickly deliver drugs across the blood-brain barrier. The paper closes with a discussion of future opportunities in the fast-changing field of brain fluid dynamics.
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Affiliation(s)
- Douglas H. Kelley
- Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627, USA
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43
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Lindstrom MR, Chavez MB, Gross-Sable EA, Hayden EY, Teplow DB. From reaction kinetics to dementia: A simple dimer model of Alzheimer's disease etiology. PLoS Comput Biol 2021; 17:e1009114. [PMID: 34280181 PMCID: PMC8321409 DOI: 10.1371/journal.pcbi.1009114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 07/29/2021] [Accepted: 05/25/2021] [Indexed: 11/19/2022] Open
Abstract
Oligomers of the amyloid β-protein (Aβ) have been implicated in the pathogenesis of Alzheimer's disease (AD) through their toxicity towards neurons. Understanding the process of oligomerization may contribute to the development of therapeutic agents, but this has been difficult due to the complexity of oligomerization and the metastability of the oligomers thus formed. To understand the kinetics of oligomer formation, and how that relates to the progression of AD, we developed models of the oligomerization process. Here, we use experimental data from cell viability assays and proxies for rate constants involved in monomer-dimer-trimer kinetics to develop a simple mathematical model linking Aβ assembly to oligomer-induced neuronal degeneration. This model recapitulates the rapid growth of disease incidence with age. It does so through incorporation of age-dependent changes in rates of Aβ monomer production and elimination. The model also describes clinical progression in genetic forms of AD (e.g., Down's syndrome), changes in hippocampal volume, AD risk after traumatic brain injury, and spatial spreading of the disease due to foci in which Aβ production is elevated. Continued incorporation of clinical and basic science data into the current model will make it an increasingly relevant model system for doing theoretical calculations that are not feasible in biological systems. In addition, terms in the model that have particularly large effects are likely to be especially useful therapeutic targets.
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Affiliation(s)
- Michael R. Lindstrom
- Department of Mathematics, University of California, Los Angeles, California, United States of America
| | - Manuel B. Chavez
- Department of Mathematics, University of California, Los Angeles, California, United States of America
| | - Elijah A. Gross-Sable
- Department of Mathematics, University of California, Los Angeles, California, United States of America
| | - Eric Y. Hayden
- Department of Neurology, David Geffen School of Medicine at the University of California, Los Angeles, California, United States of America
| | - David B. Teplow
- Department of Neurology, David Geffen School of Medicine at the University of California, Los Angeles, California, United States of America
- Molecular Biology Institute and Brain Research Institute, University of California, Los Angeles, California, United States of America
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44
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Ferris CF. Rethinking the Conditions and Mechanism for Glymphatic Clearance. Front Neurosci 2021; 15:624690. [PMID: 33897347 PMCID: PMC8060639 DOI: 10.3389/fnins.2021.624690] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 03/10/2021] [Indexed: 11/13/2022] Open
Abstract
Critical studies that form the foundation of the glymphatic system and the clearance of metabolic by-products of unwanted proteins from the brain are reviewed. Concerns are raised about studying glymphatic flow in anesthetized animals and making assumptions about the whole brain based upon data collected from a cranial window on the cortex. A new model is proposed arguing that the flow of cerebral spinal fluid and parenchymal clearance in the perivascular system of unwanted proteins is regulated by circadian changes in brain temperature and blood flow at the level of the microvasculature.
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Affiliation(s)
- Craig F Ferris
- Department Psychology and Pharmaceutical Sciences, Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
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45
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Raghunandan A, Ladron-de-Guevara A, Tithof J, Mestre H, Du T, Nedergaard M, Thomas JH, Kelley DH. Bulk flow of cerebrospinal fluid observed in periarterial spaces is not an artifact of injection. eLife 2021; 10:65958. [PMID: 33687330 PMCID: PMC7979157 DOI: 10.7554/elife.65958] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/08/2021] [Indexed: 12/24/2022] Open
Abstract
Cerebrospinal fluid (CSF) flowing through periarterial spaces is integral to the brain’s mechanism for clearing metabolic waste products. Experiments that track tracer particles injected into the cisterna magna (CM) of mouse brains have shown evidence of pulsatile CSF flow in perivascular spaces surrounding pial arteries, with a bulk flow in the same direction as blood flow. However, the driving mechanism remains elusive. Several studies have suggested that the bulk flow might be an artifact, driven by the injection itself. Here, we address this hypothesis with new in vivo experiments where tracer particles are injected into the CM using a dual-syringe system, with simultaneous injection and withdrawal of equal amounts of fluid. This method produces no net increase in CSF volume and no significant increase in intracranial pressure. Yet, particle-tracking reveals flows that are consistent in all respects with the flows observed in earlier experiments with single-syringe injection.
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Affiliation(s)
- Aditya Raghunandan
- Department of Mechanical Engineering, University of Rochester, Rochester, United States
| | - Antonio Ladron-de-Guevara
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States
| | - Jeffrey Tithof
- Department of Mechanical Engineering, University of Rochester, Rochester, United States.,Department of Mechanical Engineering, University of Minnesota, Minneapolis, United States
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States
| | - Ting Du
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, United States.,Center for Translational Neuromedicine, University of Copenhagen, Rochester, United States
| | - John H Thomas
- Department of Mechanical Engineering, University of Rochester, Rochester, United States
| | - Douglas H Kelley
- Department of Mechanical Engineering, University of Rochester, Rochester, United States
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Ji C, Yu X, Xu W, Lenahan C, Tu S, Shao A. The role of glymphatic system in the cerebral edema formation after ischemic stroke. Exp Neurol 2021; 340:113685. [PMID: 33676917 DOI: 10.1016/j.expneurol.2021.113685] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/25/2021] [Accepted: 03/01/2021] [Indexed: 12/20/2022]
Abstract
Cerebral edema following ischemic stroke is predictive of the severity of the eventual stroke related damage, however the effective treatment is limited. The glymphatic system is a recently identified waste clearance pathway in the brain, found in the paravascular space and mainly composed of astrocytes and their aquaporin-4 (AQP4) water channels. In this review, we primarily focus on the role of the glymphatic system in the formation of cerebral edema after ischemic stroke. There is still no definite conclusion whether the influx of cerebrospinal fluid (CSF) in the glymphatic system is increased or not after ischemic stroke. However, the reduced interstitial fluid (ISF) clearance after ischemic stroke is definite. Additionally, AQP4 as the most important part of glymphatic system plays a complex bimodal in cerebral edema after ischemic stroke. Most of the research has found that AQP4 deletion in animals reduces cerebral edema after acute ischemic stroke compared with wild type animal models. The mislocalization of astrocytic AQP4 was also presented after ischemic stroke. As the cerebral edema after ischemic stroke is difficult to treat, we discuss several potential treatment targets related to glymphatic system. More studies are needed to explore the role of glymphatic system in the formation of cerebral edema after ischemic stroke and develop probable treatment strategies.
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Affiliation(s)
- Caihong Ji
- Department of Neurology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xing Yu
- Department of Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Weilin Xu
- Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Cameron Lenahan
- Center for Neuroscience Research, Loma Linda University School of Medicine, Loma Linda, CA, USA; Burrell College of Osteopathic Medicine, Las Cruces, NM, USA
| | - Sheng Tu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Anwen Shao
- Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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47
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Steward CE, Venkatraman VK, Lui E, Malpas CB, Ellis KA, Cyarto EV, Vivash L, O'Brien TJ, Velakoulis D, Ames D, Masters CL, Lautenschlager NT, Bammer R, Desmond PM. Assessment of the DTI-ALPS Parameter Along the Perivascular Space in Older Adults at Risk of Dementia. J Neuroimaging 2021; 31:569-578. [PMID: 33556226 DOI: 10.1111/jon.12837] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Recently, there has been growing interest in the glymphatic system (the functional waste clearance pathway for the central nervous system and its role in flushing solutes (such as amyloid ß and tau), metabolic, and other cellular waste products in the brain. Herein, we investigate a recent potential biomarker for glymphatic activity (the diffusion tensor imaging along the perivascular space [DTI-ALPS] parameter) using diffusion MRI imaging in an elderly cohort comprising 10 cognitively normal, 10 mild cognitive impairment (MCI), and 16 Alzheimer's disease (AD). METHODS All 36 participants imaged on a Siemens 3.0T Tim Trio. Single-SE diffusion weighted Echo-planar imaging scans were acquired as well as T1 magnetization prepared rapid gradient echo, T2 axial, and susceptibility weighted imaging. Three millimeter regions of interest were drawn in the projection and association fibers adjacent to the medullary veins at the level of the lateral ventricle. The DTI-ALPS parameter was calculated in these regions and correlated with cognitive status, Mini-Mental State Examination (MMSE), and ADASCog11 measures. RESULTS Significant correlations were found between DTI-ALPS and MMSE and ADASCog11 in the right hemisphere adjusting for age, sex, and APoE ε4 status. Significant differences were also found in the right DTI-ALPS indices between cognitively normal and AD groups (P < .026) and MCI groups (P < .025) in a univariate general linear model corrected for age, sex, and APoE ε4. Significant differences in apparent diffusion coefficient between cognitively normal and AD groups were found in the right projection fibers (P = .028). CONCLUSION Further work is needed to determine the utility of DTI-ALPS index in larger elderly cohorts and whether it measures glymphatic activity.
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Affiliation(s)
- Christopher E Steward
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Vijay K Venkatraman
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Elaine Lui
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Charles B Malpas
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Neurology, Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Kathryn A Ellis
- Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia.,Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Lucy Vivash
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Neurology, Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Neurosciences, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Terence J O'Brien
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Neurosciences, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Dennis Velakoulis
- Neuropsychiatry Unit, Royal Melbourne Hospital & Melbourne Neuropsychiatry Centre, University of Melbourne, Melbourne, Victoria, Australia
| | - David Ames
- Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia.,National Ageing and Research Institute, Melbourne, Victoria, Australia.,St George's Hospital, Kew, Victoria, Australia
| | - Colin L Masters
- Florey Institute for Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Nicola T Lautenschlager
- Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia.,NorthWestern Mental Health, Melbourne Health, Melbourne, Victoria, Australia
| | - Roland Bammer
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Patricia M Desmond
- Department of Medicine and Radiology, University of Melbourne, Melbourne, Victoria, Australia
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48
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Mentink LJ, Thomas J, Melis RJF, Olde Rikkert MGM, Overeem S, Claassen JAHR. Home-EEG assessment of possible compensatory mechanisms for sleep disruption in highly irregular shift workers - The ANCHOR study. PLoS One 2020; 15:e0237622. [PMID: 33382689 PMCID: PMC7774973 DOI: 10.1371/journal.pone.0237622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 11/12/2020] [Indexed: 11/30/2022] Open
Abstract
Study objectives While poor sleep quality has been related to increased risk of Alzheimer’s disease, long-time shift workers (maritime pilots) did not manifest evidence of early Alzheimer’s disease in a recent study. We explored two hypotheses of possible compensatory mechanisms for sleep disruption: Increased efficiency in generating deep sleep during workweeks (model 1) and rebound sleep during rest weeks (model 2). Methods We used data from ten male maritime pilots (mean age: 51.6±2.4 years) with a history of approximately 18 years of irregular shift work. Subjective sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). A single lead EEG-device was used to investigate sleep in the home/work environment, quantifying total sleep time (TST), deep sleep time (DST), and deep sleep time percentage (DST%). Using multilevel models, we studied the sleep architecture of maritime pilots over time, at the transition of a workweek to a rest week. Results Maritime pilots reported worse sleep quality in workweeks compared to rest weeks (PSQI = 8.2±2.2 vs. 3.9±2.0; p<0.001). Model 1 showed a trend towards an increase in DST% of 0.6% per day during the workweek (p = 0.08). Model 2 did not display an increase in DST% in the rest week (p = 0.87). Conclusions Our findings indicated that increased efficiency in generating deep sleep during workweeks is a more likely compensatory mechanism for sleep disruption in the maritime pilot cohort than rebound sleep during rest weeks. Compensatory mechanisms for poor sleep quality might mitigate sleep disruption-related risk of developing Alzheimer’s disease. These results should be used as a starting point for future studies including larger, more diverse populations of shift workers.
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Affiliation(s)
- Lara J. Mentink
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
- * E-mail:
| | - Jana Thomas
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - René J. F. Melis
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marcel G. M. Olde Rikkert
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Sebastiaan Overeem
- Sleep Medicine Center Kempenhaeghe, Heeze, The Netherlands
- Biomedical Diagnostics Group, Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jurgen A. H. R. Claassen
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
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49
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Patel PD, Stafflinger JE, Marwitz JH, Niemeier JP, Ottens AK. Secreted Peptides for Diagnostic Trajectory Assessments in Brain Injury Rehabilitation. Neurorehabil Neural Repair 2020; 35:169-184. [PMID: 33331223 DOI: 10.1177/1545968320975428] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Rehabilitation following traumatic brain injury (TBI) significantly improves outcomes; yet TBI heterogeneity raises the need for molecular evidence of brain recovery processes to better track patient progress, evaluate therapeutic efficacy, and provide prognostication. OBJECTIVE Here, we assessed whether the trajectory of TBI-responsive peptides secreted into urine can produce a predictive model of functional recovery during TBI rehabilitation. METHODS The multivariate urinary peptidome of 12 individuals with TBI was examined using quantitative peptidomics. Measures were assessed upon admission and discharge from inpatient rehabilitation. A combination of Pavlidis template matching and partial least-squares discriminant analysis was used to build models on Disability Rating Scale (DRS) and Functional Independence Measure (FIM) scores, with participants bifurcated into more or less functional improvement groups. RESULTS The produced models exhibited high sensitivity and specificity with the area under the receiver operator curve being 0.99 for DRS- and 0.95 for FIM-based models using the top 20 discriminant peptides. Predictive ability for each model was assessed using robust leave-one-out cross-validation with Q2 statistics of 0.64 (P = .00012) and 0.62 (P = .011) for DRS- and FIM-based models, respectively, both with a high predictive accuracy of 0.875. Identified peptides that discriminated improved functional recovery reflected heightened neuroplasticity and synaptic refinement and diminished cell death and neuroinflammation, consistent with postacute TBI pathobiology. CONCLUSIONS Produced models of urine-based peptide measures reflective of ongoing recovery pathobiology can inform on rehabilitation progress after TBI, warranting further study to assess refined stratification across a larger population and efficacy in assessing therapeutic interventions.
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Affiliation(s)
- Parantap D Patel
- Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | | | | | - Janet P Niemeier
- Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Andrew K Ottens
- Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
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50
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Korte N, Nortley R, Attwell D. Cerebral blood flow decrease as an early pathological mechanism in Alzheimer's disease. Acta Neuropathol 2020; 140:793-810. [PMID: 32865691 PMCID: PMC7666276 DOI: 10.1007/s00401-020-02215-w] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/15/2020] [Accepted: 08/15/2020] [Indexed: 02/08/2023]
Abstract
Therapies targeting late events in Alzheimer's disease (AD), including aggregation of amyloid beta (Aβ) and hyperphosphorylated tau, have largely failed, probably because they are given after significant neuronal damage has occurred. Biomarkers suggest that the earliest event in AD is a decrease of cerebral blood flow (CBF). This is caused by constriction of capillaries by contractile pericytes, probably evoked by oligomeric Aβ. CBF is also reduced by neutrophil trapping in capillaries and clot formation, perhaps secondary to the capillary constriction. The fall in CBF potentiates neurodegeneration by upregulating the BACE1 enzyme that makes Aβ and by promoting tau hyperphosphorylation. Surprisingly, therefore, CBF reduction may play a crucial role in driving cognitive decline by initiating the amyloid cascade itself, or being caused by and amplifying Aβ production. Here, we review developments in this area that are neglected in current approaches to AD, with the aim of promoting novel mechanism-based therapeutic approaches.
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Affiliation(s)
- 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
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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