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Brockie S, Zhou C, Fehlings MG. Resident immune responses to spinal cord injury: role of astrocytes and microglia. Neural Regen Res 2024; 19:1678-1685. [PMID: 38103231 PMCID: PMC10960308 DOI: 10.4103/1673-5374.389630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/08/2023] [Accepted: 10/18/2023] [Indexed: 12/18/2023] Open
Abstract
Spinal cord injury can be traumatic or non-traumatic in origin, with the latter rising in incidence and prevalence with the aging demographics of our society. Moreover, as the global population ages, individuals with co-existent degenerative spinal pathology comprise a growing number of traumatic spinal cord injury cases, especially involving the cervical spinal cord. This makes recovery and treatment approaches particularly challenging as age and comorbidities may limit regenerative capacity. For these reasons, it is critical to better understand the complex milieu of spinal cord injury lesion pathobiology and the ensuing inflammatory response. This review discusses microglia-specific purinergic and cytokine signaling pathways, as well as microglial modulation of synaptic stability and plasticity after injury. Further, we evaluate the role of astrocytes in neurotransmission and calcium signaling, as well as their border-forming response to neural lesions. Both the inflammatory and reparative roles of these cells have eluded our complete understanding and remain key therapeutic targets due to their extensive structural and functional roles in the nervous system. Recent advances have shed light on the roles of glia in neurotransmission and reparative injury responses that will change how interventions are directed. Understanding key processes and existing knowledge gaps will allow future research to effectively target these cells and harness their regenerative potential.
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Affiliation(s)
- Sydney Brockie
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Cindy Zhou
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Michael G. Fehlings
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery and Spine Program, Department of Surgery, University of Toronto, Toronto, ON, Canada
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2
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Lau K, Kotzur R, Richter F. Blood-brain barrier alterations and their impact on Parkinson's disease pathogenesis and therapy. Transl Neurodegener 2024; 13:37. [PMID: 39075566 PMCID: PMC11285262 DOI: 10.1186/s40035-024-00430-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 07/11/2024] [Indexed: 07/31/2024] Open
Abstract
There is increasing evidence for blood-brain barrier (BBB) alterations in Parkinson's disease (PD), the second most common neurodegenerative disorder with rapidly rising prevalence. Altered tight junction and transporter protein levels, accumulation of α-synuclein and increase in inflammatory processes lead to extravasation of blood molecules and vessel degeneration. This could result in a self-perpetuating pathophysiology of inflammation and BBB alteration, which contribute to neurodegeneration. Toxin exposure or α-synuclein over-expression in animal models has been shown to initiate similar pathologies, providing a platform to study underlying mechanisms and therapeutic interventions. Here we provide a comprehensive review of the current knowledge on BBB alterations in PD patients and how rodent models that replicate some of these changes can be used to study disease mechanisms. Specific challenges in assessing the BBB in patients and in healthy controls are discussed. Finally, a potential role of BBB alterations in disease pathogenesis and possible implications for therapy are explored. The interference of BBB alterations with current and novel therapeutic strategies requires more attention. Brain region-specific BBB alterations could also open up novel opportunities to target specifically vulnerable neuronal subpopulations.
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Affiliation(s)
- Kristina Lau
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
| | - Rebecca Kotzur
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany
| | - Franziska Richter
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.
- Center for Systems Neuroscience, Hannover, Germany.
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Floriddia E. In conversation with Ukpong Eyo. Nat Neurosci 2024; 27:1-3. [PMID: 38052908 DOI: 10.1038/s41593-023-01532-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
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4
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Canepa E, Parodi-Rullan R, Vazquez-Torres R, Gamallo-Lana B, Guzman-Hernandez R, Lemon NL, Angiulli F, Debure L, Ilies MA, Østergaard L, Wisniewski T, Gutiérrez-Jiménez E, Mar AC, Fossati S. FDA-approved carbonic anhydrase inhibitors reduce amyloid β pathology and improve cognition, by ameliorating cerebrovascular health and glial fitness. Alzheimers Dement 2023; 19:5048-5073. [PMID: 37186121 PMCID: PMC10600328 DOI: 10.1002/alz.13063] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/09/2023] [Accepted: 03/09/2023] [Indexed: 05/17/2023]
Abstract
INTRODUCTION Cerebrovascular pathology is an early and causal hallmark of Alzheimer's disease (AD), in need of effective therapies. METHODS Based on the success of our previous in vitro studies, we tested for the first time in a model of AD and cerebral amyloid angiopathy (CAA), the carbonic anhydrase inhibitors (CAIs) methazolamide and acetazolamide, Food and Drug Administration-approved against glaucoma and high-altitude sickness. RESULTS Both CAIs reduced cerebral, vascular, and glial amyloid beta (Aβ) accumulation and caspase activation, diminished gliosis, and ameliorated cognition in TgSwDI mice. The CAIs also improved microvascular fitness and induced protective glial pro-clearance pathways, resulting in the reduction of Aβ deposition. Notably, we unveiled that the mitochondrial carbonic anhydrase-VB (CA-VB) is upregulated in TgSwDI brains, CAA and AD+CAA human subjects, and in endothelial cells upon Aβ treatment. Strikingly, CA-VB silencing specifically reduces Aβ-mediated endothelial apoptosis. DISCUSSION This work substantiates the potential application of CAIs in clinical trials for AD and CAA.
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Affiliation(s)
- Elisa Canepa
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Rebecca Parodi-Rullan
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Rafael Vazquez-Torres
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Begona Gamallo-Lana
- Department of Neuroscience and Physiology, Neuroscience Institute, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Roberto Guzman-Hernandez
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Nicole L. Lemon
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Federica Angiulli
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
| | - Ludovic Debure
- Department on Neurology, Center for Cognitive Neurology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Marc A. Ilies
- Department of Pharmaceutical Sciences and Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Temple University, Philadelphia, PA, 19140, USA
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark
| | - Thomas Wisniewski
- Department on Neurology, Center for Cognitive Neurology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Eugenio Gutiérrez-Jiménez
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark
| | - Adam C. Mar
- Department of Neuroscience and Physiology, Neuroscience Institute, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Silvia Fossati
- Alzheimer’s Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, 19140, USA
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5
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Brazhe A, Verisokin A, Verveyko D, Postnov D. Astrocytes: new evidence, new models, new roles. Biophys Rev 2023; 15:1303-1333. [PMID: 37975000 PMCID: PMC10643736 DOI: 10.1007/s12551-023-01145-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/08/2023] [Indexed: 11/19/2023] Open
Abstract
Astrocytes have been in the limelight of active research for about 3 decades now. Over this period, ideas about their function and role in the nervous system have evolved from simple assistance in energy supply and homeostasis maintenance to a complex informational and metabolic hub that integrates data on local neuronal activity, sensory and arousal context, and orchestrates many crucial processes in the brain. Rapid progress in experimental techniques and data analysis produces a growing body of data, which can be used as a foundation for formulation of new hypotheses, building new refined mathematical models, and ultimately should lead to a new level of understanding of the contribution of astrocytes to the cognitive tasks performed by the brain. Here, we highlight recent progress in astrocyte research, which we believe expands our understanding of how low-level signaling at a cellular level builds up to processes at the level of the whole brain and animal behavior. We start our review with revisiting data on the role of noradrenaline-mediated astrocytic signaling in locomotion, arousal, sensory integration, memory, and sleep. We then briefly review astrocyte contribution to the regulation of cerebral blood flow regulation, which is followed by a discussion of biophysical mechanisms underlying astrocyte effects on different brain processes. The experimental section is closed by an overview of recent experimental techniques available for modulation and visualization of astrocyte dynamics. We then evaluate how the new data can be potentially incorporated into the new mathematical models or where and how it already has been done. Finally, we discuss an interesting prospect that astrocytes may be key players in important processes such as the switching between sleep and wakefulness and the removal of toxic metabolites from the brain milieu.
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Affiliation(s)
- Alexey Brazhe
- Department of Biophysics, Biological Faculty, Lomonosov Moscow State University, Leninskie Gory, 1/24, Moscow, 119234 Russia
- Department of Molecular Neurobiology, Institute of Bioorganic Chemistry RAS, GSP-7, Miklukho-Maklay Str., 16/10, Moscow, 117997 Russia
| | - Andrey Verisokin
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, Kursk, 305000 Russia
| | - Darya Verveyko
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, Kursk, 305000 Russia
| | - Dmitry Postnov
- Department of Optics and Biophotonics, Saratov State University, Astrakhanskaya st., 83, Saratov, 410012 Russia
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Shahbazi A, Sepehrinezhad A, Vahdani E, Jamali R, Ghasempour M, Massoudian S, Sahab Negah S, Larsen FS. Gut Dysbiosis and Blood-Brain Barrier Alteration in Hepatic Encephalopathy: From Gut to Brain. Biomedicines 2023; 11:1272. [PMID: 37238943 PMCID: PMC10215854 DOI: 10.3390/biomedicines11051272] [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: 02/04/2023] [Revised: 03/20/2023] [Accepted: 03/28/2023] [Indexed: 05/28/2023] Open
Abstract
A common neuropsychiatric complication of advanced liver disease, hepatic encephalopathy (HE), impacts the quality of life and length of hospital stays. There is new evidence that gut microbiota plays a significant role in brain development and cerebral homeostasis. Microbiota metabolites are providing a new avenue of therapeutic options for several neurological-related disorders. For instance, the gut microbiota composition and blood-brain barrier (BBB) integrity are altered in HE in a variety of clinical and experimental studies. Furthermore, probiotics, prebiotics, antibiotics, and fecal microbiota transplantation have been shown to positively affect BBB integrity in disease models that are potentially extendable to HE by targeting gut microbiota. However, the mechanisms that underlie microbiota dysbiosis and its effects on the BBB are still unclear in HE. To this end, the aim of this review was to summarize the clinical and experimental evidence of gut dysbiosis and BBB disruption in HE and a possible mechanism.
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Affiliation(s)
- Ali Shahbazi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 1449614535, Iran; (A.S.); (S.M.)
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran;
| | - Ali Sepehrinezhad
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 1449614535, Iran; (A.S.); (S.M.)
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran;
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad 9919191778, Iran
| | - Edris Vahdani
- Department of Microbiology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari 4815733971, Iran;
| | - Raika Jamali
- Research Development Center, Sina Hospital, Tehran University of Medical Sciences, Tehran 1417653761, Iran
- Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran 1417653761, Iran
| | - Monireh Ghasempour
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran;
| | - Shirin Massoudian
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 1449614535, Iran; (A.S.); (S.M.)
| | - Sajad Sahab Negah
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad 9919191778, Iran
- Department of Neuroscience, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad 9919191778, Iran
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran 9815733169, Iran
| | - Fin Stolze Larsen
- Department of Intestinal Failure and Liver Diseases, Rigshospitalet, Inge Lehmanns Vej 5, 2100 Copenhagen, Denmark
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Lia A, Di Spiezio A, Speggiorin M, Zonta M. Two decades of astrocytes in neurovascular coupling. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:1162757. [PMID: 37078069 PMCID: PMC10106690 DOI: 10.3389/fnetp.2023.1162757] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/23/2023] [Indexed: 04/05/2023]
Abstract
The brain is a highly energy demanding organ, which accounts in humans for the 20% of total energy consumption at resting state although comprising only 2% of the body mass. The necessary delivery of nutrients to brain parenchyma is ensured by the cerebral circulatory system, through the exchange of glucose and oxygen (O2) at the capillary level. Notably, a tight spatial and temporal correlation exists between local increases in neuronal activity and the subsequent changes in regional cerebral blood flow. The recognized concept of neurovascular coupling (NVC), also named functional hyperemia, expresses this close relationship and stands at the basis of the modern functional brain imaging techniques. Different cellular and molecular mechanisms have been proposed to mediate this tight coupling. In this context, astrocytes are ideally positioned to act as relay elements that sense neuronal activity through their perisynaptic processes and release vasodilator agents at their endfeet in contact with brain parenchymal vessels. Two decades after the astrocyte involvement in neurovascular coupling has been proposed, we here review the experimental evidence that contributed to unraveling the molecular and cellular mechanisms underlying cerebral blood flow regulation. While traveling through the different controversies that moved the research in this field, we keep a peculiar focus on those exploring the role of astrocytes in neurovascular coupling and conclude with two sections related to methodological aspects in neurovascular research and to some pathological conditions resulting in altered neurovascular coupling.
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Affiliation(s)
- Annamaria Lia
- Neuroscience Institute, National Research Council (CNR), Padua, Italy
| | - Alessandro Di Spiezio
- Neuroscience Institute, National Research Council (CNR), Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | | | - Micaela Zonta
- Neuroscience Institute, National Research Council (CNR), Padua, Italy
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8
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Miao SH, Gao SQ, Li HX, Zhuang YS, Wang X, Li T, Gao CC, Han YL, Qiu JY, Zhou ML. Increased NOX2 expression in astrocytes leads to eNOS uncoupling through dihydrofolate reductase in endothelial cells after subarachnoid hemorrhage. Front Mol Neurosci 2023; 16:1121944. [PMID: 37063365 PMCID: PMC10097896 DOI: 10.3389/fnmol.2023.1121944] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
IntroductionEndothelial nitric oxide synthase (eNOS) uncoupling plays a significant role in acute vasoconstriction during early brain injury (EBI) after subarachnoid hemorrhage (SAH). Astrocytes in the neurovascular unit extend their foot processes around endothelia. In our study, we tested the hypothesis that increased nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) expression in astrocytes after SAH leads to eNOS uncoupling.MethodsWe utilized laser speckle contrast imaging for monitoring cortical blood flow changes in mice, nitric oxide (NO) kits to measure the level of NO, and a co-culture system to study the effect of astrocytes on endothelial cells. Moreover, the protein levels were assessed by Western blot and immunofluorescence staining. We used CCK-8 to measure the viability of astrocytes and endothelial cells, and we used the H2O2 kit to measure the H2O2 released from astrocytes. We used GSK2795039 as an inhibitor of NOX2, whereas lentivirus and adeno-associated virus were used for dihydrofolate reductase (DHFR) knockdown in vivo and in vitro.ResultsThe expression of NOX2 and the release of H2O2 in astrocytes are increased, which was accompanied by a decrease in endothelial DHFR 12 h after SAH. Moreover, the eNOS monomer/dimer ratio increased, leading to a decrease in NO and acute cerebral ischemia. All of the above were significantly alleviated after the administration of GSK2795039. However, after knocking down DHFR both in vivo and in vitro, the protective effect of GSK2795039 was greatly reversed.DiscussionThe increased level of NOX2 in astrocytes contributes to decreased DHFR in endothelial cells, thus aggravating eNOS uncoupling, which is an essential mechanism underlying acute vasoconstriction after SAH.
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Affiliation(s)
- Shu-Hao Miao
- Department of Neurosurgery, Jinling Hospital, Jinling School of Clinical Medicine, Nanjing Medical University, Nanjing, China
| | - Sheng-Qing Gao
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Hui-Xin Li
- Department of Gynecology, Women’s Hospital of Nanjing Medical University, Nanjing, China
| | - Yun-Song Zhuang
- Department of Neurosurgery, Jinling Hospital, Jinling School of Clinical Medicine, Nanjing Medical University, Nanjing, China
| | - Xue Wang
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Tao Li
- Department of Neurosurgery, Jinling Hospital, Jinling School of Clinical Medicine, Nanjing Medical University, Nanjing, China
| | - Chao-Chao Gao
- Department of Neurosurgery, Jinling Hospital, Jinling School of Clinical Medicine, Nanjing Medical University, Nanjing, China
| | - Yan-Ling Han
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Jia-Yin Qiu
- Department of Neurosurgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Meng-Liang Zhou
- Department of Neurosurgery, Jinling Hospital, Jinling School of Clinical Medicine, Nanjing Medical University, Nanjing, China
- *Correspondence: Meng-Liang Zhou,
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Human mini-blood-brain barrier models for biomedical neuroscience research: a review. Biomater Res 2022; 26:82. [PMID: 36527159 PMCID: PMC9756735 DOI: 10.1186/s40824-022-00332-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
The human blood-brain barrier (BBB) is a unique multicellular structure that is in critical demand for fundamental neuroscience studies and therapeutic evaluation. Despite substantial achievements in creating in vitro human BBB platforms, challenges in generating specifics of physiopathological relevance are viewed as impediments to the establishment of in vitro models. In this review, we provide insight into the development and deployment of in vitro BBB models that allow investigation of the physiology and pathology of neurological therapeutic avenues. First, we highlight the critical components, including cell sources, biomaterial glue collections, and engineering techniques to reconstruct a miniaturized human BBB. Second, we describe recent breakthroughs in human mini-BBBs for investigating biological mechanisms in neurology. Finally, we discuss the application of human mini-BBBs to medical approaches. This review provides strategies for understanding neurological diseases, a validation model for drug discovery, and a potential approach for generating personalized medicine.
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Chen VY, Le CT, Pottenburgh J, Siddiqui A, Park A, Asanad S, Magder L, Im LT, Saeedi OJ. A Pilot Study Assessing Retinal Blood Flow Dysregulation in Glaucoma Using Erythrocyte Mediated Velocimetry. Transl Vis Sci Technol 2022; 11:19. [PMID: 36441132 PMCID: PMC9710491 DOI: 10.1167/tvst.11.11.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Purpose The purpose of this study was to compare autoregulation of retinal arteriolar and venular blood flow in patients with glaucoma, glaucoma suspect participants, and control participants using erythrocyte mediated velocimetry. Methods This prospective cohort pilot study included 7 eyes of 5 participants with glaucoma, 15 eyes of 8 glaucoma suspect participants, and 11 eyes of 6 control participants. Mean erythrocyte velocity in retinal arterioles and venules was measured using erythrocyte mediated velocimetry at room air and after oxygen supplementation. Change in erythrocyte velocity was compared among all groups using generalized estimating equations. Results In total, 64 vessels (18 with glaucoma, 31 that were glaucoma suspect, and 15 controls) of 33 eyes of 19 participants were analyzed. There was no significant difference in baseline velocities in arterioles or venules among the three groups. With induction of hyperoxia, mean arterial erythrocyte velocity decreased in glaucoma (-7.2 ± 13.7%), which differed from controls and glaucoma suspects where erythrocyte velocity increased with hyperoxia by 4.6 ± 13.3% (P = 0.002) and 7.2 ± 21.7% (P = 0.03), respectively. A higher baseline arteriolar velocity (β = -3.9% per mm/s, P = 0.002), glaucoma diagnosis (β = -21.1%, P = 0.03), and White race (β = -20.0%, P = 0.01) were associated with decreased velocity in response to arterial hyperoxia. Conclusions Hyperoxia increased erythrocyte velocity in control and glaucoma suspect participants, but decreased erythrocyte velocity in glaucoma participants, possibly due to impaired autoregulation. Baseline velocity, glaucoma diagnosis, and White race were associated with a decrease in velocity with induction of hyperoxia. Translational Relevance The European Medicines Agency (EMA) permits precision measurements of blood flow which may aid in the development of biomarkers of glaucoma-related dysregulation of blood flow.
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Affiliation(s)
| | | | | | - Ahmed Siddiqui
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ashley Park
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Samuel Asanad
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Laurence Magder
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Lily T. Im
- University of Maryland School of Medicine, Baltimore, MD, USA
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11
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Roy P, Tomassoni D, Nittari G, Traini E, Amenta F. Effects of choline containing phospholipids on the neurovascular unit: A review. Front Cell Neurosci 2022; 16:988759. [PMID: 36212684 PMCID: PMC9541750 DOI: 10.3389/fncel.2022.988759] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
The roles of choline and of choline-containing phospholipids (CCPLs) on the maintenance and progress of neurovascular unit (NVU) integrity are analyzed. NVU is composed of neurons, glial and vascular cells ensuring the correct homeostasis of the blood-brain barrier (BBB) and indirectly the function of the central nervous system. The CCPLs phosphatidylcholine (lecithin), cytidine 5′-diphosphocholine (CDP-choline), choline alphoscerate or α-glyceryl-phosphorylcholine (α-GPC) contribute to the modulation of the physiology of the NVU cells. A loss of CCPLs contributes to the development of neurodegenerative diseases such as Alzheimer’s disease, multiple sclerosis, Parkinson’s disease. Our study has characterized the cellular components of the NVU and has reviewed the effect of lecithin, of CDP-choline and α-GPC documented in preclinical studies and in limited clinical trials on these compounds. The interesting results obtained with some CCPLs, in particular with α-GPC, probably would justify reconsideration of the most promising molecules in larger attentively controlled studies. This can also contribute to better define the role of the NVU in the pathophysiology of brain disorders characterized by vascular impairment.
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Affiliation(s)
- Proshanta Roy
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Daniele Tomassoni
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Giulio Nittari
- School of Medicinal and Health Products Sciences, University of Camerino, Camerino, Italy
| | - Enea Traini
- School of Medicinal and Health Products Sciences, University of Camerino, Camerino, Italy
| | - Francesco Amenta
- School of Medicinal and Health Products Sciences, University of Camerino, Camerino, Italy
- *Correspondence: Francesco Amenta,
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12
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Shabani Z, Schuerger J, Su H. Cellular loci involved in the development of brain arteriovenous malformations. Front Hum Neurosci 2022; 16:968369. [PMID: 36211120 PMCID: PMC9532630 DOI: 10.3389/fnhum.2022.968369] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/31/2022] [Indexed: 11/13/2022] Open
Abstract
Brain arteriovenous malformations (bAVMs) are abnormal vessels that are prone to rupture, causing life-threatening intracranial bleeding. The mechanism of bAVM formation is poorly understood. Nevertheless, animal studies revealed that gene mutation in endothelial cells (ECs) and angiogenic stimulation are necessary for bAVM initiation. Evidence collected through analyzing bAVM specimens of human and mouse models indicate that cells other than ECs also are involved in bAVM pathogenesis. Both human and mouse bAVMs vessels showed lower mural cell-coverage, suggesting a role of pericytes and vascular smooth muscle cells (vSMCs) in bAVM pathogenesis. Perivascular astrocytes also are important in maintaining cerebral vascular function and take part in bAVM development. Furthermore, higher inflammatory cytokines in bAVM tissue and blood demonstrate the contribution of inflammatory cells in bAVM progression, and rupture. The goal of this paper is to provide our current understanding of the roles of different cellular loci in bAVM pathogenesis.
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Affiliation(s)
- Zahra Shabani
- Center for Cerebrovascular Research, University of California, San Francisco, San Francisco, CA, United States
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Joana Schuerger
- Center for Cerebrovascular Research, University of California, San Francisco, San Francisco, CA, United States
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Hua Su
- Center for Cerebrovascular Research, University of California, San Francisco, San Francisco, CA, United States
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
- *Correspondence: Hua Su, ; orcid.org/0000-0003-1566-9877
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13
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Liu Y, Hua Y, Park K, Volkow ND, Pan Y, Du C. Cocaine's cerebrovascular vasoconstriction is associated with astrocytic Ca 2+ increase in mice. Commun Biol 2022; 5:936. [PMID: 36097038 PMCID: PMC9468035 DOI: 10.1038/s42003-022-03877-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022] Open
Abstract
Human and animal studies have reported widespread reductions in cerebral blood flow associated with chronic cocaine exposures. However, the molecular and cellular mechanisms underlying cerebral blood flow reductions are not well understood. Here, by combining a multimodal imaging platform with a genetically encoded calcium indicator, we simultaneously measured the effects of acute cocaine on neuronal and astrocytic activity, tissue oxygenation, hemodynamics and vascular diameter changes in the mouse cerebral cortex. Our results showed that cocaine constricted blood vessels (measured by vessel diameter Φ changes), decreasing cerebral total blood volume (HbT) and temporally reducing tissue oxygenation. Cellular imaging showed that the mean astrocytic Ca2+ dependent fluorescence [Formula: see text] increase in response to cocaine was weaker but longer lasting than the mean neuronal Ca2+ dependent fluorescence [Formula: see text] changes. Interestingly, while cocaine-induced [Formula: see text] increase was temporally correlated with tissue oxygenation change, the [Formula: see text] elevation after cocaine was in temporal correspondence with the long-lasting decrease in arterial blood volumes. To determine whether the temporal association between astrocytic activation and cocaine induced vasoconstriction reflected a causal association we inhibited astrocytic Ca2+ using GFAP-DREADD(Gi). Inhibition of astrocytes attenuated the vasoconstriction resulting from cocaine, providing evidence that astrocytes play a critical role in cocaine's vasoconstrictive effects in the brain. These results indicate that neurons and astrocytes play different roles in mediating neurovascular coupling in response to cocaine. Our findings implicate neuronal activation as the main driver of the short-lasting reduction in tissue oxygenation and astrocyte long-lasting activation as the driver of the persistent vasoconstriction with cocaine. Understanding the cellular and vascular interaction induced by cocaine will be helpful for future putative treatments to reduce cerebrovascular pathology from cocaine use.
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Affiliation(s)
- Yanzuo Liu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Yueming Hua
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Kicheon Park
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Nora D Volkow
- National Institute on Drug Abuse, Bethesda, MD, 20852, USA.
| | - Yingtian Pan
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Congwu Du
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA.
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14
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Burboa PC, Puebla M, Gaete PS, Durán WN, Lillo MA. Connexin and Pannexin Large-Pore Channels in Microcirculation and Neurovascular Coupling Function. Int J Mol Sci 2022; 23:ijms23137303. [PMID: 35806312 PMCID: PMC9266979 DOI: 10.3390/ijms23137303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 01/27/2023] Open
Abstract
Microcirculation homeostasis depends on several channels permeable to ions and/or small molecules that facilitate the regulation of the vasomotor tone, hyperpermeability, the blood–brain barrier, and the neurovascular coupling function. Connexin (Cxs) and Pannexin (Panxs) large-pore channel proteins are implicated in several aspects of vascular physiology. The permeation of ions (i.e., Ca2+) and key metabolites (ATP, prostaglandins, D-serine, etc.) through Cxs (i.e., gap junction channels or hemichannels) and Panxs proteins plays a vital role in intercellular communication and maintaining vascular homeostasis. Therefore, dysregulation or genetic pathologies associated with these channels promote deleterious tissue consequences. This review provides an overview of current knowledge concerning the physiological role of these large-pore molecule channels in microcirculation (arterioles, capillaries, venules) and in the neurovascular coupling function.
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Affiliation(s)
- Pía C. Burboa
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, 185 South Orange Avenue, Newark, NJ 07103, USA; (P.C.B.); (W.N.D.)
- Departamento de Morfología y Función, Facultad de Salud y Ciencias Sociales, Sede Santiago Centro, Universidad de las Américas, Avenue República 71, Santiago 8370040, Chile;
| | - Mariela Puebla
- Departamento de Morfología y Función, Facultad de Salud y Ciencias Sociales, Sede Santiago Centro, Universidad de las Américas, Avenue República 71, Santiago 8370040, Chile;
| | - Pablo S. Gaete
- Department of Physiology and Membrane Biology, University of California at Davis, Davis, CA 95616, USA;
| | - Walter N. Durán
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, 185 South Orange Avenue, Newark, NJ 07103, USA; (P.C.B.); (W.N.D.)
- Rutgers School of Graduate Studies, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Mauricio A. Lillo
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, 185 South Orange Avenue, Newark, NJ 07103, USA; (P.C.B.); (W.N.D.)
- Correspondence:
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15
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Li L, Zhou J, Han L, Wu X, Shi Y, Cui W, Zhang S, Hu Q, Wang J, Bai H, Liu H, Guo W, Feng D, Qu Y. The Specific Role of Reactive Astrocytes in Stroke. Front Cell Neurosci 2022; 16:850866. [PMID: 35321205 PMCID: PMC8934938 DOI: 10.3389/fncel.2022.850866] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 02/15/2022] [Indexed: 01/05/2023] Open
Abstract
Astrocytes are essential in maintaining normal brain functions such as blood brain barrier (BBB) homeostasis and synapse formation as the most abundant cell type in the central nervous system (CNS). After the stroke, astrocytes are known as reactive astrocytes (RAs) because they are stimulated by various damage-associated molecular patterns (DAMPs) and cytokines, resulting in significant changes in their reactivity, gene expression, and functional characteristics. RAs perform multiple functions after stroke. The inflammatory response of RAs may aggravate neuro-inflammation and release toxic factors to exert neurological damage. However, RAs also reduce excitotoxicity and release neurotrophies to promote neuroprotection. Furthermore, RAs contribute to angiogenesis and axonal remodeling to promote neurological recovery. Therefore, RAs' biphasic roles and mechanisms make them an effective target for functional recovery after the stroke. In this review, we summarized the dynamic functional changes and internal molecular mechanisms of RAs, as well as their therapeutic potential and strategies, in order to comprehensively understand the role of RAs in the outcome of stroke disease and provide a new direction for the clinical treatment of stroke.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Yan Qu
- Department of Neurosurgery, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
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16
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Jackson JG, Krizman E, Takano H, Lee M, Choi GH, Putt ME, Robinson MB. Activation of Glutamate Transport Increases Arteriole Diameter in v ivo: Implications for Neurovascular Coupling. Front Cell Neurosci 2022; 16:831061. [PMID: 35308116 PMCID: PMC8930833 DOI: 10.3389/fncel.2022.831061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/24/2022] [Indexed: 11/21/2022] Open
Abstract
In order to meet the energetic demands of cell-to-cell signaling, increases in local neuronal signaling are matched by a coordinated increase in local blood flow, termed neurovascular coupling. Multiple different signals from neurons, astrocytes, and pericytes contribute to this control of blood flow. Previously, several groups demonstrated that inhibition/ablation of glutamate transporters attenuates the neurovascular response. However, it was not determined if glutamate transporter activation was sufficient to increase blood flow. Here, we used multiphoton imaging to monitor the diameter of fluorescently labeled cortical arterioles in anesthetized C57/B6J mice. We delivered vehicle, glutamate transporter substrates, or a combination of a glutamate transporter substrate with various pharmacologic agents via a glass micropipette while simultaneously visualizing changes in arteriole diameter. We developed a novel image analysis method to automate the measurement of arteriole diameter in these time-lapse analyses. Using this workflow, we first conducted pilot experiments in which we focally applied L-glutamate, D-aspartate, or L-threo-hydroxyaspartate (L-THA) and measured arteriole responses as proof of concept. We subsequently applied the selective glutamate transport substrate L-THA (applied at concentrations that do not activate glutamate receptors). We found that L-THA evoked a significantly larger dilation than that observed with focal saline application. This response was blocked by co-application of the potent glutamate transport inhibitor, L-(2S,3S)-3-[3-[4-(trifluoromethyl)-benzoylamino]benzyloxy]-aspartate (TFB-TBOA). Conversely, we were unable to demonstrate a reduction of this effect through co-application of a cocktail of glutamate and GABA receptor antagonists. These studies provide the first direct evidence that activation of glutamate transport is sufficient to increase arteriole diameter. We explored potential downstream mechanisms mediating this transporter-mediated dilation by using a Ca2+ chelator or inhibitors of reversed-mode Na+/Ca2+ exchange, nitric oxide synthetase, or cyclo-oxygenase. The estimated effects and confidence intervals suggested some form of inhibition for a number of these inhibitors. Limitations to our study design prevented definitive conclusions with respect to these downstream inhibitors; these limitations are discussed along with possible next steps. Understanding the mechanisms that control blood flow are important because changes in blood flow/energy supply are implicated in several neurodegenerative disorders and are used as a surrogate measure of neuronal activity in widely used techniques such as functional magnetic resonance imaging (fMRI).
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Affiliation(s)
- Joshua G. Jackson
- Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Pediatrics, University of Pennsylvania, Philadelphia, PA, United States
| | - Elizabeth Krizman
- Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Pediatrics, University of Pennsylvania, Philadelphia, PA, United States
| | - Hajime Takano
- Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States
| | - Meredith Lee
- Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Grace H. Choi
- Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania, Philadelphia, PA, United States
| | - Mary E. Putt
- Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania, Philadelphia, PA, United States
| | - Michael B. Robinson
- Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, United States
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17
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Takahashi S. Metabolic Contribution and Cerebral Blood Flow Regulation by Astrocytes in the Neurovascular Unit. Cells 2022; 11:cells11050813. [PMID: 35269435 PMCID: PMC8909328 DOI: 10.3390/cells11050813] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 02/17/2022] [Accepted: 02/24/2022] [Indexed: 12/10/2022] Open
Abstract
The neurovascular unit (NVU) is a conceptual framework that has been proposed to better explain the relationships between the neural cells and blood vessels in the human brain, focused mainly on the brain gray matter. The major components of the NVU are the neurons, astrocytes (astroglia), microvessels, pericytes, and microglia. In addition, we believe that oligodendrocytes should also be included as an indispensable component of the NVU in the white matter. Of all these components, astrocytes in particular have attracted the interest of researchers because of their unique anatomical location; these cells are interposed between the neurons and the microvessels of the brain. Their location suggests that astrocytes might regulate the cerebral blood flow (CBF) in response to neuronal activity, so as to ensure an adequate supply of glucose and oxygen to meet the metabolic demands of the neurons. In fact, the adult human brain, which accounts for only 2% of the entire body weight, consumes approximately 20–25% of the total amount of glucose and oxygen consumed by the whole body. The brain needs a continuous supply of these essential energy sources through the CBF, because there are practically no stores of glucose or oxygen in the brain; both acute and chronic cessation of CBF can adversely affect brain functions. In addition, another important putative function of the NVU is the elimination of heat and waste materials produced by neuronal activity. Recent evidence suggests that astrocytes play pivotal roles not only in supplying glucose, but also fatty acids and amino acids to neurons. Loss of astrocytic support can be expected to lead to malfunction of the NVU as a whole, which underlies numerous neurological disorders. In this review, we shall focus on historical and recent findings with regard to the metabolic contributions of astrocytes in the NVU.
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Affiliation(s)
- Shinichi Takahashi
- Department of Neurology and Stroke, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka-shi 350-1298, Japan; ; Tel.: +81-42-984-4111 (ext. 7412) or +81-3-3353-1211 (ext. 62613); Fax: +81-42-984-0664 or +81-3-3357-5445
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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18
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van Vliet EA, Marchi N. Neurovascular unit dysfunction as a mechanism of seizures and epilepsy during aging. Epilepsia 2022; 63:1297-1313. [PMID: 35218208 PMCID: PMC9321014 DOI: 10.1111/epi.17210] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/23/2022] [Accepted: 02/23/2022] [Indexed: 11/30/2022]
Abstract
The term neurovascular unit (NVU) describes the structural and functional liaison between specialized brain endothelium, glial and mural cells, and neurons. Within the NVU, the blood‐brain barrier (BBB) is the microvascular structure regulating neuronal physiology and immune cross‐talk, and its properties adapt to brain aging. Here, we analyze a research framework where NVU dysfunction, caused by acute insults or disease progression in the aging brain, represents a converging mechanism underlying late‐onset seizures or epilepsy and neurological or neurodegenerative sequelae. Furthermore, seizure activity may accelerate brain aging by sustaining regional NVU dysfunction, and a cerebrovascular pathology may link seizures to comorbidities. Next, we focus on NVU diagnostic approaches that could be tailored to seizure conditions in the elderly. We also examine the impending disease‐modifying strategies based on the restoration of the NVU and, more in general, the homeostatic control of anti‐ and pro‐inflammatory players. We conclude with an outlook on current pre‐clinical knowledge gaps and clinical challenges pertinent to seizure onset and conditions in an aging population.
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Affiliation(s)
- Erwin A van Vliet
- Amsterdam UMC, University of Amsterdam, dept. of (Neuro)pathology, Amsterdam, the Netherlands.,University of Amsterdam, Swammerdam Institute for Life Sciences, Center for Neuroscience, Amsterdam, the Netherlands
| | - Nicola Marchi
- Cerebrovascular and Glia Research, Department of Neuroscience, Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
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19
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Kouki MA, Pritchard AB, Alder JE, Crean S. Do Periodontal Pathogens or Associated Virulence Factors Have a Deleterious Effect on the Blood-Brain Barrier, Contributing to Alzheimer's Disease? J Alzheimers Dis 2021; 85:957-973. [PMID: 34897087 DOI: 10.3233/jad-215103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The central nervous system (CNS) is protected by a highly selective barrier, the blood-brain barrier (BBB), that regulates the exchange and homeostasis of bloodborne molecules, excluding xenobiotics. This barrier forms the first line of defense by prohibiting pathogens from crossing to the CNS. Aging and chronic exposure of the BBB to pathogens renders it permeable, and this may give rise to pathology in the CNS such as Alzheimer's disease (AD). Researchers have linked pathogens associated with periodontitis to neuroinflammation and AD-like pathology in vivo and in vitro. Although the presence of periodontitis-associated bacteria has been linked to AD in several clinical studies as DNA and virulence factors were confirmed in brain samples of human AD subjects, the mechanism by which the bacteria traverse to the brain and potentially influences neuropathology is unknown. In this review, we present current knowledge about the association between periodontitis and AD, the mechanism whereby periodontal pathogens might provoke neuroinflammation and how periodontal pathogens could affect the BBB. We suggest future studies, with emphasis on the use of human in vitro models of cells associated with the BBB to unravel the pathway of entry for these bacteria to the CNS and to reveal the molecular and cellular pathways involved in initiating the AD-like pathology. In conclusion, evidence demonstrate that bacteria associated with periodontitis and their virulence factors are capable of inflecting damage to the BBB and have a role in giving rise to pathology similar to that found in AD.
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Affiliation(s)
- Mhd Ammar Kouki
- Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, UK
| | - Anna Barlach Pritchard
- Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Jane Elizabeth Alder
- Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, UK
| | - StJohn Crean
- Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
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20
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Whelan R, Hargaden GC, Knox AJS. Modulating the Blood-Brain Barrier: A Comprehensive Review. Pharmaceutics 2021; 13:1980. [PMID: 34834395 PMCID: PMC8618722 DOI: 10.3390/pharmaceutics13111980] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 12/23/2022] Open
Abstract
The highly secure blood-brain barrier (BBB) restricts drug access to the brain, limiting the molecular toolkit for treating central nervous system (CNS) diseases to small, lipophilic drugs. Development of a safe and effective BBB modulator would revolutionise the treatment of CNS diseases and future drug development in the area. Naturally, the field has garnered a great deal of attention, leading to a vast and diverse range of BBB modulators. In this review, we summarise and compare the various classes of BBB modulators developed over the last five decades-their recent advancements, advantages and disadvantages, while providing some insight into their future as BBB modulators.
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Affiliation(s)
- Rory Whelan
- School of Biological and Health Sciences, Technological University Dublin, Central Quad, Grangegorman, D07 XT95 Dublin, Ireland;
- Chemical and Structural Biology, Environmental Sustainability and Health Institute, Technological University Dublin, D07 H6K8 Dublin, Ireland
| | - Grainne C. Hargaden
- School of Chemical and Pharmaceutical Sciences, Technological University Dublin, Central Quad, Grangegorman, D07 XT95 Dublin, Ireland;
| | - Andrew J. S. Knox
- School of Biological and Health Sciences, Technological University Dublin, Central Quad, Grangegorman, D07 XT95 Dublin, Ireland;
- Chemical and Structural Biology, Environmental Sustainability and Health Institute, Technological University Dublin, D07 H6K8 Dublin, Ireland
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21
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Troy AM, Cheng HM. Human microvascular reactivity: a review of vasomodulating stimuli and non-invasive imaging assessment. Physiol Meas 2021; 42. [PMID: 34325417 DOI: 10.1088/1361-6579/ac18fd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/29/2021] [Indexed: 11/11/2022]
Abstract
The microvasculature serves an imperative function in regulating perfusion and nutrient exchange throughout the body, adaptively altering blood flow to preserve hemodynamic and metabolic homeostasis. Its normal functioning is vital to tissue health, whereas its dysfunction is present in many chronic conditions, including diabetes, heart disease, and cognitive decline. As microvascular dysfunction often appears early in disease progression, its detection can offer early diagnostic information. To detect microvascular dysfunction, one uses imaging to probe the microvasculature's ability to react to a stimulus, also known as microvascular reactivity (MVR). An assessment of MVR requires an integrated understanding of vascular physiology, techniques for stimulating reactivity, and available imaging methods to capture the dynamic response. Practical considerations, including compatibility between the selected stimulus and imaging approach, likewise require attention. In this review, we provide a comprehensive foundation necessary for informed imaging of MVR, with a particular focus on the challenging endeavor of assessing microvascular function in deep tissues.
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Affiliation(s)
- Aaron M Troy
- Institute of Biomedical Engineering, University of Toronto, Toronto, CANADA
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22
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Liu X, Shen L, Han B, Yao H. Involvement of noncoding RNA in blood-brain barrier integrity in central nervous system disease. Noncoding RNA Res 2021; 6:130-138. [PMID: 34377876 PMCID: PMC8327137 DOI: 10.1016/j.ncrna.2021.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 02/06/2023] Open
Abstract
Given the important role of the blood-brain barrier (BBB) in the central nervous system (CNS), increasing studies have been carried out to determine how the structural and functional integrity of the BBB impacts the pathogenesis of CNS diseases such as stroke, traumatic brain injuries (TBIs), and gliomas. Emerging studies have revealed that noncoding RNAs (ncRNAs) help to maintain the integrity and permeability of the BBB, thereby mediating CNS homeostasis. This review summarizes recent studies that focus on the effects of ncRNAs on the BBB in CNS diseases, including regulating the biological processes of inflammation, necrosis, and apoptosis of cells, affecting the translational dysfunction of proteins and regulating tight junctions (TJs). A comprehensive and detailed understanding of the interaction between ncRNAs and the BBB will lay a solid foundation for the development of early diagnostic methods and effective treatments for CNS diseases.
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Affiliation(s)
- Xi Liu
- School of Medicine, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Ling Shen
- School of Medicine, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Bing Han
- School of Medicine, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Honghong Yao
- School of Medicine, Southeast University, Nanjing, 210009, Jiangsu, China
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23
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Delivery of Therapeutic Agents to the Central Nervous System and the Promise of Extracellular Vesicles. Pharmaceutics 2021; 13:pharmaceutics13040492. [PMID: 33916841 PMCID: PMC8067091 DOI: 10.3390/pharmaceutics13040492] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/26/2021] [Accepted: 03/30/2021] [Indexed: 12/17/2022] Open
Abstract
The central nervous system (CNS) is surrounded by the blood–brain barrier (BBB), a semipermeable border of endothelial cells that prevents pathogens, solutes and most molecules from non-selectively crossing into the CNS. Thus, the BBB acts to protect the CNS from potentially deleterious insults. Unfortunately, the BBB also frequently presents a significant barrier to therapies, impeding passage of drugs and biologicals to target cells within the CNS. This review provides an overview of different approaches to deliver therapeutics across the BBB, with an emphasis in extracellular vesicles as delivery vehicles to the CNS.
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24
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Institoris A, Murphy-Royal C, Tarantini S, Yabluchanskiy A, Haidey JN, Csiszar A, Ungvari Z, Gordon GR. Whole brain irradiation in mice causes long-term impairment in astrocytic calcium signaling but preserves astrocyte-astrocyte coupling. GeroScience 2021; 43:197-212. [PMID: 33094399 PMCID: PMC8050172 DOI: 10.1007/s11357-020-00289-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/14/2020] [Indexed: 11/29/2022] Open
Abstract
Whole brain irradiation (WBI) therapy is an important treatment for brain metastases and potential microscopic malignancies. WBI promotes progressive cognitive dysfunction in over half of surviving patients, yet, the underlying mechanisms remain obscure. Astrocytes play critical roles in the regulation of neuronal activity, brain metabolism, and cerebral blood flow, and while neurons are considered radioresistant, astrocytes are sensitive to γ-irradiation. Hallmarks of astrocyte function are the ability to generate stimulus-induced intercellular Ca2+ signals and to move metabolic substrates through the connected astrocyte network. We tested the hypothesis that WBI-induced cognitive impairment associates with persistent impairment of astrocytic Ca2+ signaling and/or gap junctional coupling. Mice were subjected to a clinically relevant protocol of fractionated WBI, and 12 to 15 months after irradiation, we confirmed persistent cognitive impairment compared to controls. To test the integrity of astrocyte-to-astrocyte gap junctional coupling postWBI, astrocytes were loaded with Alexa-488-hydrazide by patch-based dye infusion, and the increase of fluorescence signal in neighboring astrocyte cell bodies was assessed with 2-photon microscopy in acute slices of the sensory-motor cortex. We found that WBI did not affect astrocyte-to-astrocyte gap junctional coupling. Astrocytic Ca2+ responses induced by bath administration of phenylephrine (detected with Rhod-2/AM) were also unaltered by WBI. However, an electrical stimulation protocol used in long-term potentiation (theta burst), revealed attenuated astrocyte Ca2+ responses in the astrocyte arbor and soma in WBI. Our data show that WBI causes a long-lasting decrement in synaptic-evoked astrocyte Ca2+ signals 12-15 months postirradiation, which may be an important contributor to cognitive decline seen after WBI.
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Affiliation(s)
- Adam Institoris
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Ciaran Murphy-Royal
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Stefano Tarantini
- Department of Biochemistry and Molecular Biology, Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Andriy Yabluchanskiy
- Department of Biochemistry and Molecular Biology, Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Jordan N Haidey
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Anna Csiszar
- Department of Biochemistry and Molecular Biology, Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Zoltan Ungvari
- Department of Biochemistry and Molecular Biology, Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Grant R Gordon
- Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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25
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Li C, Wang Y, Yan XL, Guo ZN, Yang Y. Pathological changes in neurovascular units: Lessons from cases of vascular dementia. CNS Neurosci Ther 2021; 27:17-25. [PMID: 33423390 PMCID: PMC7804924 DOI: 10.1111/cns.13572] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/13/2020] [Accepted: 12/14/2020] [Indexed: 12/11/2022] Open
Abstract
Vascular dementia (VD) is the second leading cause of dementia after Alzheimer's disease (AD). The decrease of cerebral blood flow (CBF) to different degrees is one of the main causes of VD. Neurovascular unit (NVU) is a vessel‐centered concept, emphasizing all the cellular components play an integrated role in maintaining the normal physiological functions of the brain. More and more evidence shows that reduced CBF causes a series of changes in NVU, such as impaired neuronal function, abnormal activation of glial cells, and changes in vascular permeability, all of which collectively play a role in the pathogenesis of VD. In this paper, we review NVU changes as CBF decreases, focusing on each cellular component of NVU. We also highlight remote ischemic preconditioning as a promising approach for VD prevention and treatment from the NVU perspective of view.
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Affiliation(s)
- Chao Li
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, the First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Yan Wang
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, the First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Xiu-Li Yan
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, the First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Zhen-Ni Guo
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, the First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Yi Yang
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, the First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
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Blood-brain barrier integrity in the pathogenesis of Alzheimer's disease. Front Neuroendocrinol 2020; 59:100857. [PMID: 32781194 DOI: 10.1016/j.yfrne.2020.100857] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 02/06/2023]
Abstract
The blood-brain barrier (BBB) tightly controls the molecular exchange between the brain parenchyma and blood. Accumulated evidence from transgenic animal Alzheimer's disease (AD) models and human AD patients have demonstrated that BBB dysfunction is a major player in AD pathology. In this review, we discuss the role of the BBB in maintaining brain integrity and how this is mediated by crosstalk between BBB-associated cells within the neurovascular unit (NVU). We then discuss the role of the NVU, in particular its endothelial cell, pericyte, and glial cell constituents, in AD pathogenesis. The effect of substances released by the neuroendocrine system in modulating BBB function and AD pathogenesis is also discussed. We perform a systematic review of currently available AD treatments specifically targeting pericytes and BBB glial cells. In summary, this review provides a comprehensive overview of BBB dysfunction in AD and a new perspective on the development of therapeutics for AD.
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Freitas-Andrade M, Raman-Nair J, Lacoste B. Structural and Functional Remodeling of the Brain Vasculature Following Stroke. Front Physiol 2020; 11:948. [PMID: 32848875 PMCID: PMC7433746 DOI: 10.3389/fphys.2020.00948] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
Maintenance of cerebral blood vessel integrity and regulation of cerebral blood flow ensure proper brain function. The adult human brain represents only a small portion of the body mass, yet about a quarter of the cardiac output is dedicated to energy consumption by brain cells at rest. Due to a low capacity to store energy, brain health is heavily reliant on a steady supply of oxygen and nutrients from the bloodstream, and is thus particularly vulnerable to stroke. Stroke is a leading cause of disability and mortality worldwide. By transiently or permanently limiting tissue perfusion, stroke alters vascular integrity and function, compromising brain homeostasis and leading to widespread consequences from early-onset motor deficits to long-term cognitive decline. While numerous lines of investigation have been undertaken to develop new pharmacological therapies for stroke, only few advances have been made and most clinical trials have failed. Overall, our understanding of the acute and chronic vascular responses to stroke is insufficient, yet a better comprehension of cerebrovascular remodeling following stroke is an essential prerequisite for developing novel therapeutic options. In this review, we present a comprehensive update on post-stroke cerebrovascular remodeling, an important and growing field in neuroscience, by discussing cellular and molecular mechanisms involved, sex differences, limitations of preclinical research design and future directions.
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Affiliation(s)
| | - Joanna Raman-Nair
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Baptiste Lacoste
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
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Yu X, Ji C, Shao A. Neurovascular Unit Dysfunction and Neurodegenerative Disorders. Front Neurosci 2020; 14:334. [PMID: 32410936 PMCID: PMC7201055 DOI: 10.3389/fnins.2020.00334] [Citation(s) in RCA: 113] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 03/20/2020] [Indexed: 12/11/2022] Open
Abstract
The neurovascular unit (NVU), composed of vascular cells, glial cells, and neurons, is the minimal functional unit of the brain. The NVU maintains integrity of the blood–brain barrier (BBB) and regulates supply of the cerebral blood flow (CBF), both of which are keys to maintaining normal brain function. BBB dysfunction and a decreased CBF are early pathophysiological changes in neurodegenerative disorders, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). In this review, we primarily focus on the NVU in AD as much research has been performed on the connection between NVU dysfunction and AD. We also discuss the role of NVU dysfunction in the pathophysiological mechanisms of PD and ALS. As most neurodegenerative diseases are difficult to treat, we discuss several potential drug targets that focus on the NVU that may inform novel vascular-targeted therapies for AD, PD, and ALS.
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Affiliation(s)
- Xing Yu
- Department of Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Caihong Ji
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Anwen Shao
- Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Bell AH, Miller SL, Castillo-Melendez M, Malhotra A. The Neurovascular Unit: Effects of Brain Insults During the Perinatal Period. Front Neurosci 2020; 13:1452. [PMID: 32038147 PMCID: PMC6987380 DOI: 10.3389/fnins.2019.01452] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/30/2019] [Indexed: 12/31/2022] Open
Abstract
The neurovascular unit (NVU) is a relatively recent concept in neuroscience that broadly describes the relationship between brain cells and their blood vessels. The NVU incorporates cellular and extracellular components involved in regulating cerebral blood flow and blood-brain barrier function. The NVU within the adult brain has attracted strong research interest and its structure and function is well described, however, the NVU in the developing brain over the fetal and neonatal period remains much less well known. One area of particular interest in perinatal brain development is the impact of known neuropathological insults on the NVU. The aim of this review is to synthesize existing literature to describe structure and function of the NVU in the developing brain, with a particular emphasis on exploring the effects of perinatal insults. Accordingly, a brief overview of NVU components and function is provided, before discussion of NVU development and how this may be affected by perinatal pathologies. We have focused this discussion around three common perinatal insults: prematurity, acute hypoxia, and chronic hypoxia. A greater understanding of processes affecting the NVU in the perinatal period may enable application of targeted therapies, as well as providing a useful basis for research as it expands further into this area.
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Affiliation(s)
- Alexander H. Bell
- Department of Paediatrics, Monash University, Melbourne, VIC, Australia
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Suzanne L. Miller
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Margie Castillo-Melendez
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Atul Malhotra
- Department of Paediatrics, Monash University, Melbourne, VIC, Australia
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Monash Newborn, Monash Children’s Hospital, Melbourne, VIC, Australia
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Abstract
The blood-brain barrier (BBB) protects the vertebrate central nervous system from harmful blood-borne, endogenous and exogenous substances to ensure proper neuronal function. The BBB describes a function that is established by endothelial cells of CNS vessels in conjunction with pericytes, astrocytes, neurons and microglia, together forming the neurovascular unit (NVU). Endothelial barrier function is crucially induced and maintained by the Wnt/β-catenin pathway and requires intact NVU for proper functionality. The BBB and the NVU are characterized by a specialized assortment of molecular specializations, providing the basis for tightening, transport and immune response functionality.The present chapter introduces state-of-the-art knowledge of BBB structure and function and highlights current research topics, aiming to understanding in more depth the cellular and molecular interactions at the NVU, determining functionality of the BBB in health and disease, and providing novel potential targets for therapeutic BBB modulation. Moreover, we highlight recent advances in understanding BBB and NVU heterogeneity within the CNS as well as their contribution to CNS physiology, such as neurovascular coupling, and pathophysiology, is discussed. Finally, we give an outlook onto new avenues of BBB research.
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Affiliation(s)
- Fabienne Benz
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stefan Liebner
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany.
- Excellence Cluster Cardio Pulmonary System (CPI), Partner Site Frankfurt, Frankfurt, Germany.
- German Center for Cardiovascular Research (DZHK), Partner Site Frankfurt/Mainz, Frankfurt, Germany.
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Dopaminergic neuroprotective effects of rotigotine via 5-HT1A receptors: Possibly involvement of metallothionein expression in astrocytes. Neurochem Int 2019; 132:104608. [PMID: 31765686 DOI: 10.1016/j.neuint.2019.104608] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 12/28/2022]
Abstract
Astrocytes exert neuroprotective effects through production of antioxidant molecules and neurotrophic factors. A recent study showed that stimulation of astrocyte serotonin 1A (5-HT1A) receptors promotes astrocyte proliferation and upregulation of the antioxidant molecules metallothionein (MT)-1,2, which protect dopaminergic neurons against oxidative stress. Rotigotine, an anti-parkinsonian drug, can bind to dopamine and 5-HT1A receptors. In this study, we examined neuroprotective effects of rotigotine in models of Parkinson's disease and involvement of astrocyte 5-HT1A receptors in neuroprotective effects of rotigotine against dopaminergic neurodegeneration. Rotigotine increased the number of astrocytes and MT-1,2 expression in cultured astrocytes. Pretreatment with conditioned media from rotigotine-treated astrocytes significantly inhibited 6-hydroxydopamine (6-OHDA)-induced dopaminergic neurotoxicity. These effects were completely blocked by a 5-HT1A antagonist or MT-1,2 specific antibody. Subcutaneous administration of rotigotine increased MT-1,2 expression in striatal astrocytes and prevented reduction of dopaminergic neurons in the substantia nigra of a 6-OHDA-lesioned mouse model of Parkinson's disease. These effects were blocked by co-administration with a 5-HT1A antagonist. These results suggest that rotigotine exerts neuroprotective effects through upregulation of MT expression in astrocytes by targeting 5-HT1A receptors. Our findings provide a possible therapeutic application of rotigotine to prevent dopaminergic neurodegeneration in Parkinson's disease.
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Pinçon A, De Montgolfier O, Akkoyunlu N, Daneault C, Pouliot P, Villeneuve L, Lesage F, Levy BI, Thorin-Trescases N, Thorin É, Ruiz M. Non-Alcoholic Fatty Liver Disease, and the Underlying Altered Fatty Acid Metabolism, Reveals Brain Hypoperfusion and Contributes to the Cognitive Decline in APP/PS1 Mice. Metabolites 2019; 9:metabo9050104. [PMID: 31130652 PMCID: PMC6572466 DOI: 10.3390/metabo9050104] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/16/2019] [Accepted: 05/21/2019] [Indexed: 12/22/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD), the leading cause of chronic liver disease, is associated with cognitive decline in middle-aged adults, but the mechanisms underlying this association are not clear. We hypothesized that NAFLD would unveil the appearance of brain hypoperfusion in association with altered plasma and brain lipid metabolism. To test our hypothesis, amyloid precursor protein/presenilin-1 (APP/PS1) transgenic mice were fed a standard diet or a high-fat, cholesterol and cholate diet, inducing NAFLD without obesity and hyperglycemia. The diet-induced NAFLD disturbed monounsaturated and polyunsaturated fatty acid (MUFAs, PUFAs) metabolism in the plasma, liver, and brain, and particularly reduced n-3 PUFAs levels. These alterations in lipid homeostasis were associated in the brain with an increased expression of Tnfα, Cox2, p21, and Nox2, reminiscent of brain inflammation, senescence, and oxidative stress. In addition, compared to wild-type (WT) mice, while brain perfusion was similar in APP/PS1 mice fed with a chow diet, NAFLD in APP/PS1 mice reveals cerebral hypoperfusion and furthered cognitive decline. NAFLD reduced plasma β40- and β42-amyloid levels and altered hepatic but not brain expression of genes involved in β-amyloid peptide production and clearance. Altogether, our results suggest that in a mouse model of Alzheimer disease (AD) diet-induced NAFLD contributes to the development and progression of brain abnormalities through unbalanced brain MUFAs and PUFAs metabolism and cerebral hypoperfusion, irrespective of brain amyloid pathology that may ultimately contribute to the pathogenesis of AD.
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Affiliation(s)
- Anthony Pinçon
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada.
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
| | - Olivia De Montgolfier
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada.
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
| | - Nilay Akkoyunlu
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
| | - Caroline Daneault
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
| | - Philippe Pouliot
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
- Department of Electrical Engineering, Ecole Polytechnique de Montréal, Montreal, QC H3T 1J4, Canada.
| | - Louis Villeneuve
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
| | - Frédéric Lesage
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
- Department of Electrical Engineering, Ecole Polytechnique de Montréal, Montreal, QC H3T 1J4, Canada.
| | - Bernard I Levy
- Institut des Vaisseaux et du Sang, Hôpital Lariboisière, 75010 Paris, France.
| | | | - Éric Thorin
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada.
| | - Matthieu Ruiz
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, QC H1T 1C8, Canada.
- Department of Medecine, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada.
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Clark VD, Layson A, Charkviani M, Muradashvili N, Lominadze D. Hyperfibrinogenemia-mediated astrocyte activation. Brain Res 2018; 1699:158-165. [PMID: 30153459 DOI: 10.1016/j.brainres.2018.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/10/2018] [Accepted: 08/22/2018] [Indexed: 12/26/2022]
Abstract
Fibrinogen (Fg)-containing plaques are associated with memory loss during various inflammatory neurodegenerative diseases such as Alzheimer's disease, multiple sclerosis, stroke, and traumatic brain injury. However, mechanisms of its action in neurovascular unit are not clear. As Fg is a high molecular weight blood protein and cannot translocate far from the vessel after extravasation, we hypothesized that it may interact with astrocytes first causing their activation. Cultured mouse cortical astrocytes were treated with Fg in the presence or absence of function-blocking anti-mouse intercellular adhesion molecule 1 (ICAM-1) antibody, or with medium alone (control). Expressions of ICAM-1 and tyrosine receptor kinase B (TrkB) as markers of astrocyte activation, and phosphorylation of TrkB (pTrkB) were assessed. Fg dose-dependently increased activation of astrocytes defined by their shape change, retraction of processes, and enhanced expressions of ICAM-1 and TrkB, and increased pTrkB. Blocking of ICAM-1 function ameliorated these Fg effects. Data suggest that Fg interacts with astrocytes causing overexpression of ICAM-1 and TrkB, and TrkB phosphorylation, and thus, astrocyte activation. Since TrkB is known to be involved in neurodegeneration, interaction of Fg with astrocytes and the resultant activation of TrkB can be a possible mechanism involved in memory reduction, which were observed in previous studies and were associated with formation of complexes of Fg deposited in extravascular space with proteins such as Amyloid beta or prion, the proteins involved in development of dementia.
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Affiliation(s)
- Vincent D Clark
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA
| | - Ailey Layson
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA
| | - Mariam Charkviani
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA
| | - Nino Muradashvili
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA; Department of Basic Medicine, Caucasus International University, Tbilisi, Georgia
| | - David Lominadze
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA; Kentucky Spinal Cord Research Center, University of Louisville, School of Medicine, Louisville, KY, USA.
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Khennouf L, Gesslein B, Brazhe A, Octeau JC, Kutuzov N, Khakh BS, Lauritzen M. Active role of capillary pericytes during stimulation-induced activity and spreading depolarization. Brain 2018; 141:2032-2046. [PMID: 30053174 PMCID: PMC6022680 DOI: 10.1093/brain/awy143] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/05/2018] [Accepted: 04/07/2018] [Indexed: 12/27/2022] Open
Abstract
Spreading depolarization is assumed to be the mechanism of migraine with aura, which is accompanied by an initial predominant hyperaemic response followed by persistent vasoconstriction. Cerebral blood flow responses are impaired in patients and in experimental animals after spreading depolarization. Understanding the regulation of cortical blood vessels during and after spreading depolarization could help patients with migraine attacks, but our knowledge of these vascular mechanisms is still incomplete. Recent findings show that control of cerebral blood flow does not only occur at the arteriole level but also at capillaries. Pericytes are vascular mural cells that can constrict or relax around capillaries, mediating local cerebral blood flow control. They participate in the constriction observed during brain ischaemia and might be involved the disruption of the microcirculation during spreading depolarization. To further understand the regulation of cerebral blood flow in spreading depolarization, we examined penetrating arterioles and capillaries with respect to vascular branching order, pericyte location and pericyte calcium responses during somatosensory stimulation and spreading depolarization. Mice expressing a red fluorescent indicator and intravenous injections of FITC-dextran were used to visualize pericytes and vessels, respectively, under two-photon microscopy. By engineering a genetically encoded calcium indicator we could record calcium changes in both pericytes around capillaries and vascular smooth muscle cells around arterioles. We show that somatosensory stimulation evoked a decrease in cytosolic calcium in pericytes located on dilating capillaries, up to the second order capillaries. Furthermore, we show that prolonged vasoconstriction following spreading depolarization is strongest in first order capillaries, with a persistent increase in pericyte calcium. We suggest that the persistence of the 'spreading cortical oligaemia' in migraine could be caused by this constriction of cortical capillaries. After spreading depolarization, somatosensory stimulation no longer evoked changes in capillary diameter and pericyte calcium. Thus, calcium changes in pericytes located on first order capillaries may be a key determinant in local blood flow control and a novel vascular mechanism in migraine. We suggest that prevention or treatment of capillary constriction in migraine with aura, which is an independent risk factor for stroke, may be clinically useful.
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Affiliation(s)
- Lila Khennouf
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Copenhagen N, Denmark
| | - Bodil Gesslein
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Copenhagen N, Denmark
| | - Alexey Brazhe
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Copenhagen N, Denmark
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, Russia
| | - J Christopher Octeau
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Nikolay Kutuzov
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Copenhagen N, Denmark
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Martin Lauritzen
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Copenhagen N, Denmark
- Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark
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Shah N, Mohammad AS, Saralkar P, Sprowls SA, Vickers SD, John D, Tallman RM, Lucke-Wold BP, Jarrell KE, Pinti M, Nolan RL, Lockman PR. Investigational chemotherapy and novel pharmacokinetic mechanisms for the treatment of breast cancer brain metastases. Pharmacol Res 2018; 132:47-68. [PMID: 29604436 PMCID: PMC5997530 DOI: 10.1016/j.phrs.2018.03.021] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 02/08/2023]
Abstract
In women, breast cancer is the most common cancer diagnosis and second most common cause of cancer death. More than half of breast cancer patients will develop metastases to the bone, liver, lung, or brain. Breast cancer brain metastases (BCBM) confers a poor prognosis, as current therapeutic options of surgery, radiation, and chemotherapy rarely significantly extend life and are considered palliative. Within the realm of chemotherapy, the last decade has seen an explosion of novel chemotherapeutics involving targeting agents and unique dosage forms. We provide a historical overview of BCBM chemotherapy, review the mechanisms of new agents such as poly-ADP ribose polymerase inhibitors, cyclin-dependent kinase 4/6 inhibitors, phosphatidyl inositol 3-kinaseinhibitors, estrogen pathway antagonists for hormone-receptor positive BCBM; tyrosine kinase inhibitors, antibodies, and conjugates for HER2+ BCBM; repurposed cytotoxic chemotherapy for triple negative BCBM; and the utilization of these new agents and formulations in ongoing clinical trials. The mechanisms of novel dosage formulations such as nanoparticles, liposomes, pegylation, the concepts of enhanced permeation and retention, and drugs utilizing these concepts involved in clinical trials are also discussed. These new treatments provide a promising outlook in the treatment of BCBM.
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Affiliation(s)
- Neal Shah
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Afroz S Mohammad
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Pushkar Saralkar
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Samuel A Sprowls
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Schuyler D Vickers
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Devin John
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Rachel M Tallman
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Brandon P Lucke-Wold
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Katherine E Jarrell
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Mark Pinti
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Richard L Nolan
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
| | - Paul R Lockman
- West Virginia University, Health Sciences Center, School of Pharmacy, Department of Basic Pharmaceutical Sciences, Morgantown, WV 26506, USA.
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36
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The role of astrocytic calcium and TRPV4 channels in neurovascular coupling. J Comput Neurosci 2017; 44:97-114. [PMID: 29152668 DOI: 10.1007/s10827-017-0671-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 10/16/2017] [Accepted: 10/23/2017] [Indexed: 12/12/2022]
Abstract
Neuronal activity evokes a localised change in cerebral blood flow in a response known as neurovascular coupling (NVC). Although NVC has been widely studied the exact mechanisms that mediate this response remain unclear; in particular the role of astrocytic calcium is controversial. Mathematical modelling can be a useful tool for investigating the contribution of various signalling pathways towards NVC and for analysing the underlying cellular mechanisms. The lumped parameter model of a neurovascular unit with both potassium and nitric oxide (NO) signalling pathways and comprised of neurons, astrocytes, and vascular cells has been extended to include the glutamate induced astrocytic calcium pathway with epoxyeicosatrienoic acid (EET) signalling and the stretch dependent TRPV4 calcium channel on the astrocytic endfoot. Results show that the potassium pathway governs the fast onset of vasodilation while the NO pathway has a delayed response, maintaining dilation longer following neuronal stimulation. Increases in astrocytic calcium concentration via the calcium signalling pathway and/or TRPV4 channel to levels consistent with experimental data are insufficient for inducing either vasodilation or constriction, in contrast to a number of experimental results. It is shown that the astrocyte must depolarise in order to produce a significant potassium flux through the astrocytic BK channel. However astrocytic calcium is shown to strengthen potassium induced NVC by opening the BK channel further, consequently allowing more potassium into the perivascular space. The overall effect is vasodilation with a higher maximal vessel radius.
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Beaudin AE, Hartmann SE, Pun M, Poulin MJ. Human cerebral blood flow control during hypoxia: focus on chronic pulmonary obstructive disease and obstructive sleep apnea. J Appl Physiol (1985) 2017; 123:1350-1361. [DOI: 10.1152/japplphysiol.00352.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 08/01/2017] [Accepted: 08/07/2017] [Indexed: 01/06/2023] Open
Abstract
The brain is a vital organ that relies on a constant and adequate blood flow to match oxygen and glucose delivery with the local metabolic demands of active neurons. Thus exquisite regulation of cerebral blood flow (CBF) is particularly important under hypoxic conditions to prevent a detrimental decrease in the partial pressure of oxygen within the brain tissues. Cerebrovascular sensitivity to hypoxia, assessed as the change in CBF during a hypoxic challenge, represents the capacity of cerebral vessels to respond to, and compensate for, a reduced oxygen supply, and has been shown to be impaired or blunted in a number of conditions. For instance, this is observed with aging, and in clinical conditions such as untreated obstructive sleep apnea (OSA) and in healthy humans exposed to intermittent hypoxia. This review will 1) provide a brief overview of cerebral blood flow regulation and results of pharmacological intervention studies which we have performed to better elucidate the basic mechanisms of cerebrovascular regulation in humans; and 2) present data from studies in clinical and healthy populations, using a translational physiology approach, to investigate human CBF control during hypoxia. Results from studies in patients with chronic obstructive pulmonary disease and OSA will be presented to identify the effects of the disease processes on cerebrovascular sensitivity to hypoxia. Data emerging from experimental human models of intermittent hypoxia during wakefulness will also be reviewed to highlight the effects of intermittent hypoxia on the brain.
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Affiliation(s)
- Andrew E. Beaudin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Sara E. Hartmann
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Matiram Pun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Marc J. Poulin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Yamazaki Y, Kanekiyo T. Blood-Brain Barrier Dysfunction and the Pathogenesis of Alzheimer's Disease. Int J Mol Sci 2017; 18:ijms18091965. [PMID: 28902142 PMCID: PMC5618614 DOI: 10.3390/ijms18091965] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 01/22/2023] Open
Abstract
Brain capillary endothelial cells form the blood-brain barrier (BBB), which is covered with basement membranes and is also surrounded by pericytes and astrocyte end-feet in the neurovascular unit. The BBB tightly regulates the molecular exchange between the blood flow and brain parenchyma, thereby regulating the homeostasis of the central nervous system (CNS). Thus, dysfunction of the BBB is likely involved in the pathogenesis of several neurological diseases, including Alzheimer’s disease (AD). While amyloid-β (Aβ) deposition and neurofibrillary tangle formation in the brain are central pathological hallmarks in AD, cerebrovascular lesions and BBB alteration have also been shown to frequently coexist. Although further clinical studies should clarify whether BBB disruption is a specific feature of AD pathogenesis, increasing evidence indicates that each component of the neurovascular unit is significantly affected in the presence of AD-related pathologies in animal models and human patients. Conversely, since some portions of Aβ are eliminated along the neurovascular unit and across the BBB, disturbing the pathways may result in exacerbated Aβ accumulation in the brain. Thus, current evidence suggests that BBB dysfunction may causatively and consequently contribute to AD pathogenesis, forming a vicious cycle between brain Aβ accumulation and neurovascular unit impairments during disease progression.
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Affiliation(s)
- Yu Yamazaki
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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Sten S, Lundengård K, Witt S, Cedersund G, Elinder F, Engström M. Neural inhibition can explain negative BOLD responses: A mechanistic modelling and fMRI study. Neuroimage 2017; 158:219-231. [DOI: 10.1016/j.neuroimage.2017.07.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/03/2017] [Accepted: 07/02/2017] [Indexed: 12/13/2022] Open
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Li H, Bui BV, Cull G, Wang F, Wang L. Glial Cell Contribution to Basal Vessel Diameter and Pressure-Initiated Vascular Responses in Rat Retina. Invest Ophthalmol Vis Sci 2017; 58:1-8. [PMID: 28055098 PMCID: PMC5225997 DOI: 10.1167/iovs.16-20804] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to test the hypothesis that retinal glial cells modify basal vessel diameter and pressure-initiated vascular regulation in rat retina. Methods In rats, L-2-aminoadipic acid (LAA, 10 nM) was intravitreally injected to inhibit glial cell activity. Twenty-four hours following injection, retinal glial intracellular calcium (Ca2+) was labeled with the fluorescent calcium indicator Fluo-4/AM (F4, 1 mM). At 110 minutes after injection, intraocular pressure (IOP) was elevated from 20 to 50 mm Hg. Prior to and during IOP elevation, Ca2+ and retinal vessel diameter were assessed using a spectral-domain optical coherence tomography/confocal scanning laser ophthalmoscope. Dynamic changes in Ca2+ and diameter from IOP elevation were quantified. The response in LAA-treated eyes was compared with vehicle treated control eyes. Results L-2-Aminoadipic acid treatment significantly reduced F4-positive cells in the retina (LAA, 16 ± 20 vs. control, 55 ± 37 cells/mm2; P = 0.02). Twenty-four hours following LAA treatment, basal venous diameter was increased from 38.9 ± 3.9 to 51.8 ± 6.4 μm (P < 0.0001, n = 20), whereas arterial diameter was unchanged (from 30.3 ± 3.5 to 30.7 ± 2.8 μm; P = 0.64). In response to IOP elevation, LAA-treated eyes showed a smaller increase in glial cell Ca2+ around both arteries and veins in comparison with control (P < 0.001 for both). There was also significantly greater IOP-induced vasoconstriction in both vessel types (P = 0.05 and P = 0.02, respectively; n = 6 each). Conclusions The results suggest that glial cells can modulate basal retinal venous diameter and contribute to pressure-initiated vascular responses.
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Affiliation(s)
- Hui Li
- Department of Ophthalmology, The Tenth People's Hospital, Shanghai, Tongji University School of Medicine, Shanghai, China 2Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Grant Cull
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA
| | - Fang Wang
- Department of Ophthalmology, The Tenth People's Hospital, Shanghai, Tongji University School of Medicine, Shanghai, China
| | - Lin Wang
- Department of Ophthalmology, The Tenth People's Hospital, Shanghai, Tongji University School of Medicine, Shanghai, China 2Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA
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Theodorakis PE, Müller EA, Craster RV, Matar OK. Physical insights into the blood-brain barrier translocation mechanisms. Phys Biol 2017; 14:041001. [PMID: 28586313 DOI: 10.1088/1478-3975/aa708a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The number of individuals suffering from diseases of the central nervous system (CNS) is growing with an aging population. While candidate drugs for many of these diseases are available, most of these pharmaceutical agents cannot reach the brain rendering most of the drug therapies that target the CNS inefficient. The reason is the blood-brain barrier (BBB), a complex and dynamic interface that controls the influx and efflux of substances through a number of different translocation mechanisms. Here, we present these mechanisms providing, also, the necessary background related to the morphology and various characteristics of the BBB. Moreover, we discuss various numerical and simulation approaches used to study the BBB, and possible future directions based on multi-scale methods. We anticipate that this review will motivate multi-disciplinary research on the BBB aiming at the design of effective drug therapies.
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Oheim M, Schmidt E, Hirrlinger J. Local energy on demand: Are 'spontaneous' astrocytic Ca 2+-microdomains the regulatory unit for astrocyte-neuron metabolic cooperation? Brain Res Bull 2017; 136:54-64. [PMID: 28450076 DOI: 10.1016/j.brainresbull.2017.04.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/18/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022]
Abstract
Astrocytes are a neural cell type critically involved in maintaining brain energy homeostasis as well as signaling. Like neurons, astrocytes are a heterogeneous cell population. Cortical astrocytes show a complex morphology with a highly branched aborization and numerous fine processes ensheathing the synapses of neighboring neurons, and typically extend one process connecting to blood vessels. Recent studies employing genetically encoded fluorescent calcium (Ca2+) indicators have described 'spontaneous' localized Ca2+-transients in the astrocyte periphery that occur asynchronously, independently of signals in other parts of the cells, and that do not involve somatic Ca2+ transients; however, neither it is known whether these Ca2+-microdomains occur at or near neuronal synapses nor have their molecular basis nor downstream effector(s) been identified. In addition to Ca2+ microdomains, sodium (Na+) transients occur in astrocyte subdomains, too, most likely as a consequence of Na+ co-transport with the neurotransmitter glutamate, which also regulates mitochondrial movements locally - as do cytoplasmic Ca2+ levels. In this review, we cover various aspects of these local signaling events and discuss how structural and biophysical properties of astrocytes might foster such compartmentation. Astrocytes metabolically interact with neurons by providing energy substrates to active neurons. As a single astrocyte branch covers hundreds to thousands of synapses, it is tempting to speculate that these metabolic interactions could occur localized to specific subdomains of astrocytes, perhaps even at the level of small groups of synapses. We discuss how astrocytic metabolism might be regulated at this scale and which signals might contribute to its regulation. We speculate that the astrocytic structures that light up transiently as Ca2+-microdomains might be the functional units of astrocytes linking signaling and metabolic processes to adapt astrocytic function to local energy demands. The understanding of these local regulatory and metabolic interactions will be fundamental to fully appreciate the complexity of brain energy homeostasis as well as its failure in disease and may shed new light on the controversy about neuron-glia bi-directional signaling at the tripartite synapse.
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Affiliation(s)
- Martin Oheim
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France.
| | - Elke Schmidt
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany; Dept. of Neurogenetics, Max-Planck-Institute for Experimental Medicine, D-37075 Göttingen, Germany.
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Hemodynamic Changes Associated with Interictal Spikes Induced by Acute Models of Focal Epilepsy in Rats: A Simultaneous Electrocorticography and Near-Infrared Spectroscopy Study. Brain Topogr 2017; 30:390-407. [DOI: 10.1007/s10548-016-0541-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/15/2016] [Indexed: 02/07/2023]
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McConnell HL, Kersch CN, Woltjer RL, Neuwelt EA. The Translational Significance of the Neurovascular Unit. J Biol Chem 2016; 292:762-770. [PMID: 27920202 DOI: 10.1074/jbc.r116.760215] [Citation(s) in RCA: 194] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mammalian brain is supplied with blood by specialized vasculature that is structurally and functionally distinct from that of the periphery. A defining feature of this vasculature is a physical blood-brain barrier (BBB). The BBB separates blood components from the brain microenvironment, regulating the entry and exit of ions, nutrients, macromolecules, and energy metabolites. Over the last two decades, physiological studies of cerebral blood flow dynamics have demonstrated that substantial intercellular communication occurs between cells of the vasculature and the neurons and glia that abut the vasculature. These findings suggest that the BBB does not function independently, but as a module within the greater context of a multicellular neurovascular unit (NVU) that includes neurons, astrocytes, pericytes, and microglia as well as the blood vessels themselves. Here, we describe the roles of these NVU components as well as how they act in concert to modify cerebrovascular function and permeability in health and in select diseases.
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Affiliation(s)
- Heather L McConnell
- From the Departments of Neurology, Pathology, Neurosurgery, and Veterans Affairs, Oregon Health & Science University, Portland, Oregon 97239-2941
| | - Cymon N Kersch
- From the Departments of Neurology, Pathology, Neurosurgery, and Veterans Affairs, Oregon Health & Science University, Portland, Oregon 97239-2941
| | - Randall L Woltjer
- From the Departments of Neurology, Pathology, Neurosurgery, and Veterans Affairs, Oregon Health & Science University, Portland, Oregon 97239-2941
| | - Edward A Neuwelt
- From the Departments of Neurology, Pathology, Neurosurgery, and Veterans Affairs, Oregon Health & Science University, Portland, Oregon 97239-2941
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Ravin R, Blank PS, Busse B, Ravin N, Vira S, Bezrukov L, Waters H, Guerrero-Cazares H, Quinones-Hinojosa A, Lee PR, Fields RD, Bezrukov SM, Zimmerberg J. Blast shockwaves propagate Ca(2+) activity via purinergic astrocyte networks in human central nervous system cells. Sci Rep 2016; 6:25713. [PMID: 27162174 PMCID: PMC4861979 DOI: 10.1038/srep25713] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 04/21/2016] [Indexed: 12/26/2022] Open
Abstract
In a recent study of the pathophysiology of mild, blast-induced traumatic brain injury (bTBI) the exposure of dissociated, central nervous system (CNS) cells to simulated blast resulted in propagating waves of elevated intracellular Ca2+. Here we show, in dissociated human CNS cultures, that these calcium waves primarily propagate through astrocyte-dependent, purinergic signaling pathways that are blocked by P2 antagonists. Human, compared to rat, astrocytes had an increased calcium response and prolonged calcium wave propagation kinetics, suggesting that in our model system rat CNS cells are less responsive to simulated blast. Furthermore, in response to simulated blast, human CNS cells have increased expressions of a reactive astrocyte marker, glial fibrillary acidic protein (GFAP) and a protease, matrix metallopeptidase 9 (MMP-9). The conjoint increased expression of GFAP and MMP-9 and a purinergic ATP (P2) receptor antagonist reduction in calcium response identifies both potential mechanisms for sustained changes in brain function following primary bTBI and therapeutic strategies targeting abnormal astrocyte activity.
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Affiliation(s)
- Rea Ravin
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA.,Celoptics Inc., Rockville, MD 20852, USA
| | - Paul S Blank
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
| | - Brad Busse
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
| | - Nitay Ravin
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA.,Celoptics Inc., Rockville, MD 20852, USA
| | - Shaleen Vira
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
| | - Ludmila Bezrukov
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
| | - Hang Waters
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
| | | | | | - Philip R Lee
- Section on Nervous System Development and Plasticity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3713, USA
| | - R Douglas Fields
- Section on Nervous System Development and Plasticity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3713, USA
| | - Sergey M Bezrukov
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-0924, USA
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
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Han L, Kong DK, Zheng MQ, Murikinati S, Ma C, Yuan P, Li L, Tian D, Cai Q, Ye C, Holden D, Park JH, Gao X, Thomas JL, Grutzendler J, Carson RE, Huang Y, Piepmeier JM, Zhou J. Increased Nanoparticle Delivery to Brain Tumors by Autocatalytic Priming for Improved Treatment and Imaging. ACS NANO 2016; 10:4209-18. [PMID: 26967254 PMCID: PMC5257033 DOI: 10.1021/acsnano.5b07573] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The blood-brain barrier (BBB) is partially disrupted in brain tumors. Despite the gaps in the BBB, there is an inadequate amount of pharmacological agents delivered into the brain. Thus, the low delivery efficiency renders many of these agents ineffective in treating brain cancer. In this report, we proposed an "autocatalytic" approach for increasing the transport of nanoparticles into the brain. In this strategy, a small number of nanoparticles enter into the brain via transcytosis or through the BBB gaps. After penetrating the BBB, the nanoparticles release BBB modulators, which enables more nanoparticles to be transported, creating a positive feedback loop for increased delivery. Specifically, we demonstrated that these autocatalytic brain tumor-targeting poly(amine-co-ester) terpolymer nanoparticles (ABTT NPs) can readily cross the BBB and preferentially accumulate in brain tumors at a concentration of 4.3- and 94.0-fold greater than that in the liver and in brain regions without tumors, respectively. We further demonstrated that ABTT NPs were capable of mediating brain cancer gene therapy and chemotherapy. Our results suggest ABTT NPs can prime the brain to increase the systemic delivery of therapeutics for treating brain malignancies.
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Affiliation(s)
- Liang Han
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Derek K. Kong
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Ming-qiang Zheng
- PET Center, Department of Diagnostic Radiology, Yale University, New Haven, CT 06510, USA
| | | | - Chao Ma
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Peng Yuan
- Department of Neurology, Yale University, New Haven, CT 06510, USA
| | - Liyuan Li
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Daofeng Tian
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Qiang Cai
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Chunlin Ye
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
| | - Daniel Holden
- PET Center, Department of Diagnostic Radiology, Yale University, New Haven, CT 06510, USA
| | - June-Hee Park
- Department of Neurology, Yale University, New Haven, CT 06510, USA
| | - Xiaobin Gao
- Department of Pathology, Yale University, New Haven, CT 06510, USA
| | - Jean-Leon Thomas
- Department of Neurology, Yale University, New Haven, CT 06510, USA
| | | | - Richard E. Carson
- PET Center, Department of Diagnostic Radiology, Yale University, New Haven, CT 06510, USA
| | - Yiyun Huang
- PET Center, Department of Diagnostic Radiology, Yale University, New Haven, CT 06510, USA
| | | | - Jiangbing Zhou
- Department of Neurosurgery, Yale University, New Haven, CT 06511, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
- Correspondence: Jiangbing Zhou, 310 Cedar Street, FMB 410, New Haven, CT 06510, Tel: 203-785-5327,
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Guyenet PG, Bayliss DA, Stornetta RL, Ludwig MG, Kumar NN, Shi Y, Burke PGR, Kanbar R, Basting TM, Holloway BB, Wenker IC. Proton detection and breathing regulation by the retrotrapezoid nucleus. J Physiol 2016; 594:1529-51. [PMID: 26748771 PMCID: PMC4799966 DOI: 10.1113/jp271480] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/04/2016] [Indexed: 01/26/2023] Open
Abstract
We discuss recent evidence which suggests that the principal central respiratory chemoreceptors are located within the retrotrapezoid nucleus (RTN) and that RTN neurons are directly sensitive to [H(+) ]. RTN neurons are glutamatergic. In vitro, their activation by [H(+) ] requires expression of a proton-activated G protein-coupled receptor (GPR4) and a proton-modulated potassium channel (TASK-2) whose transcripts are undetectable in astrocytes and the rest of the lower brainstem respiratory network. The pH response of RTN neurons is modulated by surrounding astrocytes but genetic deletion of RTN neurons or deletion of both GPR4 and TASK-2 virtually eliminates the central respiratory chemoreflex. Thus, although this reflex is regulated by innumerable brain pathways, it seems to operate predominantly by modulating the discharge rate of RTN neurons, and the activation of RTN neurons by hypercapnia may ultimately derive from their intrinsic pH sensitivity. RTN neurons increase lung ventilation by stimulating multiple aspects of breathing simultaneously. They stimulate breathing about equally during quiet wake and non-rapid eye movement (REM) sleep, and to a lesser degree during REM sleep. The activity of RTN neurons is regulated by inhibitory feedback and by excitatory inputs, notably from the carotid bodies. The latter input operates during normo- or hypercapnia but fails to activate RTN neurons under hypocapnic conditions. RTN inhibition probably limits the degree of hyperventilation produced by hypocapnic hypoxia. RTN neurons are also activated by inputs from serotonergic neurons and hypothalamic neurons. The absence of RTN neurons probably underlies the sleep apnoea and lack of chemoreflex that characterize congenital central hypoventilation syndrome.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Ruth L Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | | | - Natasha N Kumar
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Yingtang Shi
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Peter G R Burke
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Roy Kanbar
- Department of Pharmaceutical Sciences, Lebanese American University, Beyrouth, Lebanon
| | - Tyler M Basting
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Benjamin B Holloway
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Ian C Wenker
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
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Capani F, Quarracino C, Caccuri R, Sica REP. Astrocytes As the Main Players in Primary Degenerative Disorders of the Human Central Nervous System. Front Aging Neurosci 2016; 8:45. [PMID: 26973519 PMCID: PMC4777729 DOI: 10.3389/fnagi.2016.00045] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 12/23/2015] [Indexed: 12/22/2022] Open
Abstract
Along the last years it has been demonstrated that non-neural cells play a major role in the pathogenesis of the primary degenerative disorders (PDDs) of the human central nervous system. Among them, astrocytes coordinate and participate in many different and complex metabolic processes, in close interaction with neurons. Moreover, increasing experimental evidence hints an early astrocytic dysfunction in these diseases. In this mini review we summarize the astrocytic behavior in PDDs, with special consideration to the experimental observations where astrocytic pathology precedes the development of neuronal dysfunction. We also suggest a different approach that could be consider in human investigations in Alzheimer’s and Parkinson’s disease. We believe that the study of PDDs with human brain samples may hold the key of a paradigmatic physiopathological process in which astrocytes might be the main players.
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Affiliation(s)
- Francisco Capani
- Instituto de Investigaciones Cardiologicas ININCA UBA CONICETBuenos Aires, Argentina; Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de ChileTemuco, Chile
| | - Cecilia Quarracino
- Instituto de Investigaciones Cardiologicas ININCA UBA CONICET Buenos Aires, Argentina
| | - Roberto Caccuri
- Instituto de Investigaciones Cardiologicas ININCA UBA CONICET Buenos Aires, Argentina
| | - Roberto E P Sica
- Instituto de Investigaciones Cardiologicas ININCA UBA CONICET Buenos Aires, Argentina
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50
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Gordon GRJ, Howarth C, MacVicar BA. Bidirectional Control of Blood Flow by Astrocytes: A Role for Tissue Oxygen and Other Metabolic Factors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:209-19. [PMID: 27343099 DOI: 10.1007/978-1-4899-7678-9_15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Altering cerebral blood flow through the control of cerebral vessel diameter is critical so that the delivery of molecules important for proper brain functioning is matched to the activity level of neurons. Although the close relationship of brain glia known as astrocytes with cerebral blood vessels has long been recognized, it is only recently that these cells have been demonstrated to translate information on the activity level and energy demands of neurons to the vasculature. In particular, astrocytes respond to elevations in extracellular glutamate as a consequence of synaptic transmission through the activation of group 1 metabotropic glutamate receptors. These Gq-protein coupled receptors elevate intracellular calcium via IP3 signaling. A close examination of astrocyte endfeet calcium signals has been shown to cause either vasoconstriction or vasodilation. Common to both vasomotor responses is the generation of arachidonic acid in astrocytes by calcium sensitive phospholipase A2. Vasoconstriction ensues from the conversion of arachidonic acid to 20-hydroxyeicosatetraenoic acid, while vasodilation ensues from the production of epoxyeicosatrienoic acids or prostaglandins. Factors that determine whether constrictor or dilatory pathways predominate include brain oxygen, lactate, adenosine as well as nitric oxide. Changing the oxygen level itself leads to many downstream changes that facilitate the switch from vasoconstriction at high oxygen to vasodilation at low oxygen. These findings highlight the importance of astrocytes as sensors of neural activity and metabolism to coordinate the delivery of essential nutrients via the blood to the working cells.
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Affiliation(s)
- Grant R J Gordon
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
| | - Clare Howarth
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Brian A MacVicar
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
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