1
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Morris GP, Foster CG, Sutherland BA, Grubb S. Microglia contact cerebral vasculature through gaps between astrocyte endfeet. J Cereb Blood Flow Metab 2024:271678X241280775. [PMID: 39253821 DOI: 10.1177/0271678x241280775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
The close spatial relationship between microglia and cerebral blood vessels implicates microglia in vascular development, homeostasis and disease. In this study we used the publicly available Cortical MM^3 electron microscopy dataset to systematically investigate microglial interactions with the vasculature. Our analysis revealed that approximately 20% of microglia formed direct contacts with blood vessels through gaps between adjacent astrocyte endfeet. We termed these contact points "plugs". Plug-forming microglia exhibited closer proximity to blood vessels than non-plug forming microglia and formed multiple plugs, predominantly near the soma, ranging in surface area from ∼0.01 μm2 to ∼15 μm2. Plugs were enriched at the venule end of the vascular tree and displayed a preference for contacting endothelial cells over pericytes at a ratio of 3:1. In summary, we provide novel insights into the ultrastructural relationship between microglia and the vasculature, laying a foundation for understanding how these contacts contribute to the functional cross-talk between microglia and cells of the vasculature in health and disease.
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Affiliation(s)
- Gary P Morris
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Catherine G Foster
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Brad A Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Søren Grubb
- Center for Translational Neuromedicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark
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2
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Profaci CP, Harvey SS, Bajc K, Zhang TZ, Jeffrey DA, Zhang AZ, Nemec KM, Davtyan H, O'Brien CA, McKinsey GL, Longworth A, McMullen TP, Capocchi JK, Gonzalez JG, Lawson DA, Arnold TD, Davalos D, Blurton-Jones M, Dabertrand F, Bennett FC, Daneman R. Microglia are not necessary for maintenance of blood-brain barrier properties in health, but PLX5622 alters brain endothelial cholesterol metabolism. Neuron 2024; 112:2910-2921.e7. [PMID: 39142282 DOI: 10.1016/j.neuron.2024.07.015] [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: 11/07/2022] [Revised: 05/03/2024] [Accepted: 07/21/2024] [Indexed: 08/16/2024]
Abstract
Microglia, the resident immune cells of the central nervous system, are intimately involved in the brain's most basic processes, from pruning neural synapses during development to preventing excessive neuronal activity throughout life. Studies have reported both helpful and harmful roles for microglia at the blood-brain barrier (BBB) in the context of disease. However, less is known about microglia-endothelial cell interactions in the healthy brain. To investigate the role of microglia at a healthy BBB, we used the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 to deplete microglia and analyzed the BBB ultrastructure, permeability, and transcriptome. Interestingly, we found that, despite their direct contact with endothelial cells, microglia are not necessary for the maintenance of BBB structure, function, or gene expression in the healthy brain. However, we found that PLX5622 treatment alters brain endothelial cholesterol metabolism. This effect was independent from microglial depletion, suggesting that PLX5622 has off-target effects on brain vasculature.
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Affiliation(s)
- Caterina P Profaci
- Department of Pharmacology, University of California, San Diego, La Jolla, San Diego, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, San Diego, CA, USA.
| | - Sean S Harvey
- Department of Pharmacology, University of California, San Diego, La Jolla, San Diego, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, San Diego, CA, USA
| | - Kaja Bajc
- Department of Pharmacology, University of California, San Diego, La Jolla, San Diego, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, San Diego, CA, USA
| | - Tony Z Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, San Diego, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, San Diego, CA, USA
| | - Danielle A Jeffrey
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Alexander Z Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, San Diego, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, San Diego, CA, USA
| | - Kelsey M Nemec
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hayk Davtyan
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA; Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, USA
| | - Carleigh A O'Brien
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gabriel L McKinsey
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Aaron Longworth
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Timothy P McMullen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Joia K Capocchi
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA; Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, USA
| | - Jessica G Gonzalez
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Devon A Lawson
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Thomas D Arnold
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Dimitrios Davalos
- Department of Neurosciences, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA
| | - Mathew Blurton-Jones
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA; Sue and Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA, USA; Department of Neurobiology & Behavior, University of California, Irvine, Irvine, CA, USA
| | - Fabrice Dabertrand
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - F Chris Bennett
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Richard Daneman
- Department of Pharmacology, University of California, San Diego, La Jolla, San Diego, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, San Diego, CA, USA
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3
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Calado M, Ferreira R, Pires D, Santos-Costa Q, Anes E, Brites D, Azevedo-Pereira JM. Unravelling the triad of neuroinvasion, neurodissemination, and neuroinflammation of human immunodeficiency virus type 1 in the central nervous system. Rev Med Virol 2024; 34:e2534. [PMID: 38588024 DOI: 10.1002/rmv.2534] [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: 11/22/2023] [Revised: 03/05/2024] [Accepted: 03/28/2024] [Indexed: 04/10/2024]
Abstract
Since the identification of human immunodeficiency virus type 1 (HIV-1) in 1983, many improvements have been made to control viral replication in the peripheral blood and to treat opportunistic infections. This has increased life expectancy but also the incidence of age-related central nervous system (CNS) disorders and HIV-associated neurodegeneration/neurocognitive impairment and depression collectively referred to as HIV-associated neurocognitive disorders (HAND). HAND encompasses a spectrum of different clinical presentations ranging from milder forms such as asymptomatic neurocognitive impairment or mild neurocognitive disorder to a severe HIV-associated dementia (HAD). Although control of viral replication and suppression of plasma viral load with combination antiretroviral therapy has reduced the incidence of HAD, it has not reversed milder forms of HAND. The objective of this review, is to describe the mechanisms by which HIV-1 invades and disseminates in the CNS, a crucial event leading to HAND. The review will present the evidence that underlies the relationship between HIV infection and HAND. Additionally, recent findings explaining the role of neuroinflammation in the pathogenesis of HAND will be discussed, along with prospects for treatment and control.
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Affiliation(s)
- Marta Calado
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Rita Ferreira
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - David Pires
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Center for Interdisciplinary Research in Health, Católica Medical School, Universidade Católica Portuguesa, Estrada Octávio Pato, Rio de Mouro, Portugal
| | - Quirina Santos-Costa
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Elsa Anes
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Dora Brites
- Neuroinflammation, Signaling and Neuroregeneration Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - José Miguel Azevedo-Pereira
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
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4
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Lénárt N, Cserép C, Császár E, Pósfai B, Dénes Á. Microglia-neuron-vascular interactions in ischemia. Glia 2024; 72:833-856. [PMID: 37964690 DOI: 10.1002/glia.24487] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/24/2023] [Accepted: 10/24/2023] [Indexed: 11/16/2023]
Abstract
Cerebral ischemia is a devastating condition that results in impaired blood flow in the brain leading to acute brain injury. As the most common form of stroke, occlusion of cerebral arteries leads to a characteristic sequence of pathophysiological changes in the brain tissue. The mechanisms involved, and comorbidities that determine outcome after an ischemic event appear to be highly heterogeneous. On their own, the processes leading to neuronal injury in the absence of sufficient blood supply to meet the metabolic demand of the cells are complex and manifest at different temporal and spatial scales. While the contribution of non-neuronal cells to stroke pathophysiology is increasingly recognized, recent data show that microglia, the main immune cells of the central nervous system parenchyma, play previously unrecognized roles in basic physiological processes beyond their inflammatory functions, which markedly change during ischemic conditions. In this review, we aim to discuss some of the known microglia-neuron-vascular interactions assumed to contribute to the acute and delayed pathologies after cerebral ischemia. Because the mechanisms of neuronal injury have been extensively discussed in several excellent previous reviews, here we focus on some recently explored pathways that may directly or indirectly shape neuronal injury through microglia-related actions. These discoveries suggest that modulating gliovascular processes in different forms of stroke and other neurological disorders might have presently unexplored therapeutic potential in combination with neuroprotective and flow restoration strategies.
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Affiliation(s)
- Nikolett Lénárt
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Csaba Cserép
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Eszter Császár
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Pósfai
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Ádám Dénes
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
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5
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Harry GJ. Developmental Associations between Neurovascularization and Microglia Colonization. Int J Mol Sci 2024; 25:1281. [PMID: 38279280 PMCID: PMC10816009 DOI: 10.3390/ijms25021281] [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: 12/30/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/28/2024] Open
Abstract
The temporal and spatial pattern of microglia colonization and vascular infiltration of the nervous system implies critical associated roles in early stages of nervous system development. Adding to existing reviews that cover a broad spectrum of the various roles of microglia during brain development, the current review will focus on the developmental ontogeny and interdependency between the colonization of the nervous system with yolk sac derived macrophages and vascularization. Gaining a better understanding of the timing and the interdependency of these two processes will significantly contribute to the interpretation of data generated regarding alterations in either process during early development. Additionally, such knowledge should provide a framework for understanding the influence of the early gestational environmental and the impact of genetics, disease, disorders, or exposures on the early developing nervous system and the potential for long-term and life-time effects.
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Affiliation(s)
- G Jean Harry
- Mechanistic Toxicology Branch, Division of Translational Toxicology, National Institute Environmental Health Sciences, 111 T.W. Alexander Drive, Research Triangle Park, Durham, NC 27709, USA
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6
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Harry GJ. Microglia Colonization Associated with Angiogenesis and Neural Cell Development. ADVANCES IN NEUROBIOLOGY 2024; 37:163-178. [PMID: 39207692 DOI: 10.1007/978-3-031-55529-9_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
The temporal and spatial pattern of microglia colonization of the nervous system implies a role in early stages of organ development including cell proliferation, differentiation, and neurovascularization. As microglia colonize and establish within the developing nervous system, they assume a neural-specific identity and contribute to key developmental events. Their association around blood vessels implicates them in development of the vascular system or vice versa. A similar association has been reported for neural cell proliferation and associated phenotypic shifts and for cell fate differentiation to neuronal or glial phenotypes. These processes are accomplished by phagocytic activities, cell-cell contact relationships, and secretion of various factors. This chapter will present data currently available from studies evaluating the dynamic and interactive nature of these processes throughout the progression of nervous system development.
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Affiliation(s)
- G Jean Harry
- Mechanistic Toxicology Branch, Division of Translational Toxicology, National Institute Environmental Health Sciences, Research Triangle Park, NC, USA.
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7
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McDonald B, Barth K, Schmidt MHH. The origin of brain malignancies at the blood-brain barrier. Cell Mol Life Sci 2023; 80:282. [PMID: 37688612 PMCID: PMC10492883 DOI: 10.1007/s00018-023-04934-1] [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: 05/17/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/11/2023]
Abstract
Despite improvements in extracranial therapy, survival rate for patients suffering from brain metastases remains very poor. This is coupled with the incidence of brain metastases continuing to rise. In this review, we focus on core contributions of the blood-brain barrier to the origin of brain metastases. We first provide an overview of the structure and function of the blood-brain barrier under physiological conditions. Next, we discuss the emerging idea of a pre-metastatic niche, namely that secreted factors and extracellular vesicles from a primary tumor site are able to travel through the circulation and prime the neurovasculature for metastatic invasion. We then consider the neurotropic mechanisms that circulating tumor cells possess or develop that facilitate disruption of the blood-brain barrier and survival in the brain's parenchyma. Finally, we compare and contrast brain metastases at the blood-brain barrier to the primary brain tumor, glioma, examining the process of vessel co-option that favors the survival and outgrowth of brain malignancies.
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Affiliation(s)
- Brennan McDonald
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany.
| | - Kathrin Barth
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany
| | - Mirko H H Schmidt
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany
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8
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Morris GP, Foster CG, Courtney J, Collins JM, Cashion JM, Brown LS, Howells DW, DeLuca GC, Canty AJ, King AE, Ziebell JM, Sutherland BA. Microglia directly associate with pericytes in the central nervous system. Glia 2023; 71:1847-1869. [PMID: 36994950 PMCID: PMC10952742 DOI: 10.1002/glia.24371] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/15/2023] [Accepted: 03/20/2023] [Indexed: 03/31/2023]
Abstract
Cerebral blood flow (CBF) is important for the maintenance of brain function and its dysregulation has been implicated in Alzheimer's disease (AD). Microglia associations with capillaries suggest they may play a role in the regulation of CBF or the blood-brain-barrier (BBB). We explored the relationship between microglia and pericytes, a vessel-resident cell type that has a major role in the control of CBF and maintenance of the BBB, discovering a spatially distinct subset of microglia that closely associate with pericytes. We termed these pericyte-associated microglia (PEM). PEM are present throughout the brain and spinal cord in NG2DsRed × CX3 CR1+/GFP mice, and in the human frontal cortex. Using in vivo two-photon microscopy, we found microglia residing adjacent to pericytes at all levels of the capillary tree and found they can maintain their position for at least 28 days. PEM can associate with pericytes lacking astroglial endfeet coverage and capillary vessel width is increased beneath pericytes with or without an associated PEM, but capillary width decreases if a pericyte loses a PEM. Deletion of the microglia fractalkine receptor (CX3 CR1) did not disrupt the association between pericytes and PEM. Finally, we found the proportion of microglia that are PEM declines in the superior frontal gyrus in AD. In summary, we identify microglia that specifically associate with pericytes and find these are reduced in number in AD, which may be a novel mechanism contributing to vascular dysfunction in neurodegenerative diseases.
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Affiliation(s)
- Gary P. Morris
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Catherine G. Foster
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jo‐Maree Courtney
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jessica M. Collins
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jake M. Cashion
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Lachlan S. Brown
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - David W. Howells
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Gabriele C. DeLuca
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Alison J. Canty
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
- Global Brain Health InstituteTrinity CollegeDublinIreland
| | - Anna E. King
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Jenna M. Ziebell
- Wicking Dementia Research and Education Centre, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
| | - Brad A. Sutherland
- Tasmanian School of Medicine, College of Health and MedicineUniversity of TasmaniaHobartTasmaniaAustralia
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Critical Role of Neuronal Vps35 in Blood Vessel Branching and Maturation in Developing Mouse Brain. Biomedicines 2022; 10:biomedicines10071653. [PMID: 35884959 PMCID: PMC9313219 DOI: 10.3390/biomedicines10071653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/17/2022] Open
Abstract
Vps35 (vacuolar protein sorting 35), a key component of retromer, plays a crucial role in selective retrieval of transmembrane proteins from endosomes to trans-Golgi networks. Dysfunctional Vps35/retromer is a risk factor for the development of neurodegenerative diseases. Vps35 is highly expressed in developing pyramidal neurons, both in the mouse neocortex and hippocampus, Although embryonic neuronal Vps35’s function in promoting neuronal terminal differentiation and survival is evident, it remains unclear whether and how neuronal Vps35 communicates with other types of brain cells, such as blood vessels (BVs), which are essential for supplying nutrients to neurons. Dysfunctional BVs contribute to the pathogenesis of various neurodegenerative disorders. Here, we provide evidence for embryonic neuronal Vps35 as critical for BV branching and maturation in the developing mouse brain. Selectively knocking out (KO) Vps35 in mouse embryonic, not postnatal, neurons results in reductions in BV branching and density, arteriole diameter, and BV-associated pericytes and microglia but an increase in BV-associated reactive astrocytes. Deletion of microglia by PLX3397 enhances these BV deficits in mutant mice. These results reveal the function of neuronal Vps35 in neurovascular coupling in the developing mouse brain and implicate BV-associated microglia as underlying this event.
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10
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Barkaway A, Attwell D, Korte N. Immune-vascular mural cell interactions: consequences for immune cell trafficking, cerebral blood flow, and the blood-brain barrier. NEUROPHOTONICS 2022; 9:031914. [PMID: 35581998 PMCID: PMC9107322 DOI: 10.1117/1.nph.9.3.031914] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
Brain barriers are crucial sites for cerebral energy supply, waste removal, immune cell migration, and solute exchange, all of which maintain an appropriate environment for neuronal activity. At the capillary level, where the largest area of brain-vascular interface occurs, pericytes adjust cerebral blood flow (CBF) by regulating capillary diameter and maintain the blood-brain barrier (BBB) by suppressing endothelial cell (EC) transcytosis and inducing tight junction expression between ECs. Pericytes also limit the infiltration of circulating leukocytes into the brain where resident microglia confine brain injury and provide the first line of defence against invading pathogens. Brain "waste" is cleared across the BBB into the blood, phagocytosed by microglia and astrocytes, or removed by the flow of cerebrospinal fluid (CSF) through perivascular routes-a process driven by respiratory motion and the pulsation of the heart, arteriolar smooth muscle, and possibly pericytes. "Dirty" CSF exits the brain and is probably drained around olfactory nerve rootlets and via the dural meningeal lymphatic vessels and possibly the skull bone marrow. The brain is widely regarded as an immune-privileged organ because it is accessible to few antigen-primed leukocytes. Leukocytes enter the brain via the meninges, the BBB, and the blood-CSF barrier. Advances in genetic and imaging tools have revealed that neurological diseases significantly alter immune-brain barrier interactions in at least three ways: (1) the brain's immune-privileged status is compromised when pericytes are lost or lymphatic vessels are dysregulated; (2) immune cells release vasoactive molecules to regulate CBF, modulate arteriole stiffness, and can plug and eliminate capillaries which impairs CBF and possibly waste clearance; and (3) immune-vascular interactions can make the BBB leaky via multiple mechanisms, thus aggravating the influx of undesirable substances and cells. Here, we review developments in these three areas and briefly discuss potential therapeutic avenues for restoring brain barrier functions.
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Affiliation(s)
- Anna Barkaway
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - David Attwell
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Nils Korte
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
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11
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McKenna M, Filteau JR, Butler B, Sluis K, Chungyoun M, Schimek N, Nance E. Organotypic whole hemisphere brain slice models to study the effects of donor age and oxygen-glucose-deprivation on the extracellular properties of cortical and striatal tissue. J Biol Eng 2022; 16:14. [PMID: 35698088 PMCID: PMC9195469 DOI: 10.1186/s13036-022-00293-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/21/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The brain extracellular environment is involved in many critical processes associated with neurodevelopment, neural function, and repair following injury. Organization of the extracellular matrix and properties of the extracellular space vary throughout development and across different brain regions, motivating the need for platforms that provide access to multiple brain regions at different stages of development. We demonstrate the utility of organotypic whole hemisphere brain slices as a platform to probe regional and developmental changes in the brain extracellular environment. We also leverage whole hemisphere brain slices to characterize the impact of cerebral ischemia on different regions of brain tissue. RESULTS Whole hemisphere brain slices taken from postnatal (P) day 10 and P17 rats retained viable, metabolically active cells through 14 days in vitro (DIV). Oxygen-glucose-deprivation (OGD), used to model a cerebral ischemic event in vivo, resulted in reduced slice metabolic activity and elevated cell death, regardless of slice age. Slices from P10 and P17 brains showed an oligodendrocyte and microglia-driven proliferative response after OGD exposure, higher than the proliferative response seen in DIV-matched normal control slices. Multiple particle tracking in oxygen-glucose-deprived brain slices revealed that oxygen-glucose-deprivation impacts the extracellular environment of brain tissue differently depending on brain age and brain region. In most instances, the extracellular space was most difficult to navigate immediately following insult, then gradually provided less hindrance to extracellular nanoparticle diffusion as time progressed. However, changes in diffusion were not universal across all brain regions and ages. CONCLUSIONS We demonstrate whole hemisphere brain slices from P10 and P17 rats can be cultured up to two weeks in vitro. These brain slices provide a viable platform for studying both normal physiological processes and injury associated mechanisms with control over brain age and region. Ex vivo OGD impacted cortical and striatal brain tissue differently, aligning with preexisting data generated in in vivo models. These data motivate the need to account for both brain region and age when investigating mechanisms of injury and designing potential therapies for cerebral ischemia.
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Affiliation(s)
- Michael McKenna
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Jeremy R Filteau
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Brendan Butler
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Kenneth Sluis
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Michael Chungyoun
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA
| | - Nels Schimek
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Elizabeth Nance
- Department of Chemical Engineering, University of Washington, 105 Benson Hall, Box 351750, Seattle, WA, 98195-1750, USA. .,e-Science Institute, University of Washington, Seattle, WA, USA. .,Department of Bioengineering, University of Washington, Seattle, WA, USA.
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12
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Miller-Rhodes P, Li H, Velagapudi R, Chiang W, Terrando N, Gelbard HA. URMC-099 prophylaxis prevents hippocampal vascular vulnerability and synaptic damage in an orthopedic model of delirium superimposed on dementia. FASEB J 2022; 36:e22343. [PMID: 35535564 PMCID: PMC9175136 DOI: 10.1096/fj.202200184rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 11/11/2022]
Abstract
Systemic perturbations can drive a neuroimmune cascade after surgical trauma, including affecting the blood-brain barrier (BBB), activating microglia, and contributing to cognitive deficits such as delirium. Delirium superimposed on dementia (DSD) is a particularly debilitating complication that renders the brain further vulnerable to neuroinflammation and neurodegeneration, albeit these molecular mechanisms remain poorly understood. Here, we have used an orthopedic model of tibial fracture/fixation in APPSwDI/mNos2-/- AD (CVN-AD) mice to investigate relevant pathogenetic mechanisms underlying DSD. We conducted the present study in 6-month-old CVN-AD mice, an age at which we speculated amyloid-β pathology had not saturated BBB and neuroimmune functioning. We found that URMC-099, our brain-penetrant anti-inflammatory neuroprotective drug, prevented inflammatory endothelial activation, breakdown of the BBB, synapse loss, and microglial activation in our DSD model. Taken together, our data link post-surgical endothelial activation, microglial MafB immunoreactivity, and synapse loss as key substrates for DSD, all of which can be prevented by URMC-099.
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Affiliation(s)
- Patrick Miller-Rhodes
- Center for Neurotherapeutics Discovery, Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA.,Neuroscience Graduate Program, University of Rochester Medical Center, Rochester, New York, USA
| | - Herman Li
- Center for Neurotherapeutics Discovery, Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
| | - Ravikanth Velagapudi
- Department of Anesthesiology, Center for Translational Pain Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Wesley Chiang
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, USA
| | - Niccolò Terrando
- Department of Anesthesiology, Center for Translational Pain Medicine, Duke University Medical Center, Durham, North Carolina, USA.,Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.,Department of Immunology, Duke University Medical Center, Durham, North Carolina, USA
| | - Harris A Gelbard
- Center for Neurotherapeutics Discovery, Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA.,Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA.,Department of Neuroscience, University of Rochester Medical Center, Rochester, New York, USA.,Department of Pediatrics, University of Rochester Medical Center, Rochester, New York, USA.,Department of Microbiology & Immunology, University of Rochester Medical Center, Rochester, New York, USA
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13
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Spiteri AG, Wishart CL, Pamphlett R, Locatelli G, King NJC. Microglia and monocytes in inflammatory CNS disease: integrating phenotype and function. Acta Neuropathol 2022; 143:179-224. [PMID: 34853891 PMCID: PMC8742818 DOI: 10.1007/s00401-021-02384-2] [Citation(s) in RCA: 93] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/11/2021] [Accepted: 11/11/2021] [Indexed: 02/08/2023]
Abstract
In neurological diseases, the actions of microglia, the resident myeloid cells of the CNS parenchyma, may diverge from, or intersect with, those of recruited monocytes to drive immune-mediated pathology. However, defining the precise roles of each cell type has historically been impeded by the lack of discriminating markers and experimental systems capable of accurately identifying them. Our ability to distinguish microglia from monocytes in neuroinflammation has advanced with single-cell technologies, new markers and drugs that identify and deplete them, respectively. Nevertheless, the focus of individual studies on particular cell types, diseases or experimental approaches has limited our ability to connect phenotype and function more widely and across diverse CNS pathologies. Here, we critically review, tabulate and integrate the disease-specific functions and immune profiles of microglia and monocytes to provide a comprehensive atlas of myeloid responses in viral encephalitis, demyelination, neurodegeneration and ischemic injury. In emphasizing the differential roles of microglia and monocytes in the severe neuroinflammatory disease of viral encephalitis, we connect inflammatory pathways common to equally incapacitating diseases with less severe inflammation. We examine these findings in the context of human studies and highlight the benefits and inherent limitations of animal models that may impede or facilitate clinical translation. This enables us to highlight common and contrasting, non-redundant and often opposing roles of microglia and monocytes in disease that could be targeted therapeutically.
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14
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Augusto-Oliveira M, Arrifano GP, Delage CI, Tremblay MÈ, Crespo-Lopez ME, Verkhratsky A. Plasticity of microglia. Biol Rev Camb Philos Soc 2021; 97:217-250. [PMID: 34549510 DOI: 10.1111/brv.12797] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 02/06/2023]
Abstract
Microglial cells are the scions of foetal macrophages which invade the neural tube early during embryogenesis. The nervous tissue environment instigates the phenotypic metamorphosis of foetal macrophages into idiosyncratic surveilling microglia, which are generally characterised by a small cell body and highly ramified motile processes that constantly scan the nervous tissue for signs of changes in homeostasis and allow microglia to perform crucial homeostatic functions. The surveilling microglial phenotype is evolutionarily conserved from early invertebrates to humans. Despite this evolutionary conservation, microglia show substantial heterogeneity in their gene and protein expression, as well as morphological appearance. These differences are age, region and context specific and reflect a high degree of plasticity underlying the life-long adaptation of microglia, supporting the exceptional adaptive capacity of the central nervous system. Microgliocytes are essential elements of cellular network formation and refinement in the developing nervous tissue. Several distinct patrolling modes of microglial processes contribute to the formation, modification, and pruning of synapses; to the support and protection of neurones through microglial-somatic junctions; and to the control of neuronal and axonal excitability by specific microglia-axonal contacts. In pathology, microglia undergo proliferation and reactive remodelling known as microgliosis, which is context dependent, yet represents an evolutionarily conserved defence response. Microgliosis results in the emergence of multiple disease and context-specific reactive states; in addition, neuropathology is associated with the appearance of specific protective or recovery microglial forms. In summary, the plasticity of microglia supports the development and functional activity of healthy nervous tissue and provides highly sophisticated defences against disease.
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Affiliation(s)
- Marcus Augusto-Oliveira
- Laboratório de Farmacologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-110, Belém, Brazil
| | - Gabriela P Arrifano
- Laboratório de Farmacologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-110, Belém, Brazil
| | - Charlotte Isabelle Delage
- Division of Medical Sciences, Medical Sciences Building, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Marie-Ève Tremblay
- Division of Medical Sciences, Medical Sciences Building, University of Victoria, Victoria, BC, V8P 5C2, Canada.,Axe Neurosciences, Centre de Recherche du CHU de Québec-Université Laval, 2705 Boulevard Laurier, Québec City, QC, G1V 4G2, Canada.,Neurology and Neurosurgery Department, McGill University, 3801 University Street, Montreal, QC, H3A 2B4, Canada.,Department of Molecular Medicine, Université Laval, Pavillon Ferdinand-Vandry, Bureau 4835, 1050 Avenue de la Médecine, Québec City, QC, G1V 0A6, Canada.,Department of Biochemistry and Molecular Biology, The University of British Columbia, Life Sciences Center, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Maria Elena Crespo-Lopez
- Laboratório de Farmacologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-110, Belém, Brazil
| | - Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT, U.K.,Achucarro Center for Neuroscience, IKERBASQUE, 48011, Bilbao, Spain.,Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania
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15
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Microglia-Derived Exosomes Improve Spinal Cord Functional Recovery after Injury via Inhibiting Oxidative Stress and Promoting the Survival and Function of Endothelia Cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:1695087. [PMID: 34484559 PMCID: PMC8413072 DOI: 10.1155/2021/1695087] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/07/2021] [Indexed: 02/06/2023]
Abstract
Traumatic spinal cord injury (SCI) is a devastating disease of the central nervous system with long-term disability and high mortality worldwide. Revascularization following SCI provides nutritional supports to rebuild and maintain the homeostasis of neuronal networks, and the subsequent promotion of angiogenesis is beneficial for functional recovery. Oxidative stress drastically produced following SCI has been contributed to endothelial dysfunction and the limited endogenous repair of microvasculature. Recently, exosomes, being regarded as potential therapeutic candidates for many kinds of diseases, have attracted great attentions due to its high bioavailability, safety, and stability. Microglia have been reported to exhibit proangiogenic function and guide the forming of vasculature during tissue repair. However, the specific role of microglia-derived exosomes (MG-Exos) played in SCI is still largely unknown. In the present study, we aimed to evaluate whether MG-Exos could protect spinal cord microvascular endothelial cells (SCMECs) against the toxic effects of oxidative stress, thus promote SCMECs' survival and function. We also investigated the protective effects of MG-Exos in the mouse model of SCI to verify their capability. Our results demonstrated that MG-Exo treatment significantly decreased the level of oxidative stress (ROS), as well as did the protein levels of NOX2 when bEnd.3 cells were exposed to H2O2-induced oxidative stress in vitro and in vivo. Functional assays showed that MG-Exos could improve the survival and the ability of tube formation and migration in H2O2-induced bEnd.3 in vitro. Moreover, MG-Exos exhibited the positive effects on vascular regeneration and cell proliferation, as well as functional recovery, in the mouse model of SCI. Mechanically, the keap1/Nrf2/HO-1 signaling pathway was also investigated in order to unveil its molecular mechanism, and the results showed that MG-Exos could increase the protein levels of Nrf2 and HO-1 via inhibiting the keap1; they also triggered the expression of its downstream antioxidative-related genes, such as NQo1, Gclc, Cat, and Gsx1. Our findings indicated that MG-Exos exerted an antioxidant effect and positively modulated vascular regeneration and neurological functional recovery post-SCI by activating keap1/Nrf2/HO-1 signaling.
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16
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Hanslik KL, Marino KM, Ulland TK. Modulation of Glial Function in Health, Aging, and Neurodegenerative Disease. Front Cell Neurosci 2021; 15:718324. [PMID: 34531726 PMCID: PMC8439422 DOI: 10.3389/fncel.2021.718324] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/27/2021] [Indexed: 01/15/2023] Open
Abstract
In the central nervous system (CNS), glial cells, such as microglia and astrocytes, are normally associated with support roles including contributions to energy metabolism, synaptic plasticity, and ion homeostasis. In addition to providing support for neurons, microglia and astrocytes function as the resident immune cells in the brain. The glial function is impacted by multiple aspects including aging and local CNS changes caused by neurodegeneration. During aging, microglia and astrocytes display alterations in their homeostatic functions. For example, aged microglia and astrocytes exhibit impairments in the lysosome and mitochondrial function as well as in their regulation of synaptic plasticity. Recent evidence suggests that glia can also alter the pathology associated with many neurodegenerative disorders including Alzheimer's disease (AD) and Parkinson's disease (PD). Shifts in the microbiome can impact glial function as well. Disruptions in the microbiome can lead to aberrant microglial and astrocytic reactivity, which can contribute to an exacerbation of disease and neuronal dysfunction. In this review, we will discuss the normal physiological functions of microglia and astrocytes, summarize novel findings highlighting the role of glia in aging and neurodegenerative diseases, and examine the contribution of microglia and astrocytes to disease progression.
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Affiliation(s)
- Kendra L. Hanslik
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Kaitlyn M. Marino
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Tyler K. Ulland
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
- Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI, United States
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17
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Borst K, Prinz M. Deciphering the heterogeneity of myeloid cells during neuroinflammation in the single-cell era. Brain Pathol 2020; 30:1192-1207. [PMID: 33058309 PMCID: PMC8018048 DOI: 10.1111/bpa.12910] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 08/23/2020] [Accepted: 10/12/2020] [Indexed: 12/13/2022] Open
Abstract
Multiple sclerosis (MS) is a disabling neuroinflammatory disease, which is little understood and lacks a sufficient therapeutic regimen. Myeloid cells have repeatedly shown to play a pivotal role in the disease progression. During homeostasis, only the CNS‐resident microglia and CNS‐associated macrophages are present in the CNS. Neuroinflammation causes peripheral immune cells to infiltrate the CNS contributing to disease progression and neurological sequelae. The differential involvement of the diverse peripheral and resident myeloid cell subsets to the disease pathogenesis and outcome are highly debated and difficult to assess. However, novel technological advances (new mouse models, single‐cell RNA‐Sequencing, and CYTOF) have improved the depth of immune profiling, which allows the characterization of distinct myeloid subsets. This review provides an overview of current knowledge on the phenotypes and roles of these different myeloid subsets in neuroinflammatory disease and their therapeutic relevance.
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Affiliation(s)
- Katharina Borst
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Marco Prinz
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
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18
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Comer AL, Carrier M, Tremblay MÈ, Cruz-Martín A. The Inflamed Brain in Schizophrenia: The Convergence of Genetic and Environmental Risk Factors That Lead to Uncontrolled Neuroinflammation. Front Cell Neurosci 2020; 14:274. [PMID: 33061891 PMCID: PMC7518314 DOI: 10.3389/fncel.2020.00274] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/03/2020] [Indexed: 12/12/2022] Open
Abstract
Schizophrenia is a disorder with a heterogeneous etiology involving complex interplay between genetic and environmental risk factors. The immune system is now known to play vital roles in nervous system function and pathology through regulating neuronal and glial development, synaptic plasticity, and behavior. In this regard, the immune system is positioned as a common link between the seemingly diverse genetic and environmental risk factors for schizophrenia. Synthesizing information about how the immune-brain axis is affected by multiple factors and how these factors might interact in schizophrenia is necessary to better understand the pathogenesis of this disease. Such knowledge will aid in the development of more translatable animal models that may lead to effective therapeutic interventions. Here, we provide an overview of the genetic risk factors for schizophrenia that modulate immune function. We also explore environmental factors for schizophrenia including exposure to pollution, gut dysbiosis, maternal immune activation and early-life stress, and how the consequences of these risk factors are linked to microglial function and dysfunction. We also propose that morphological and signaling deficits of the blood-brain barrier, as observed in some individuals with schizophrenia, can act as a gateway between peripheral and central nervous system inflammation, thus affecting microglia in their essential functions. Finally, we describe the diverse roles that microglia play in response to neuroinflammation and their impact on brain development and homeostasis, as well as schizophrenia pathophysiology.
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Affiliation(s)
- Ashley L. Comer
- Graduate Program for Neuroscience, Boston University, Boston, MA, United States
- Department of Biology, Boston University, Boston, MA, United States
- Neurophotonics Center, Boston University, Boston, MA, United States
- Center for Systems Neuroscience, Boston University, Boston, MA, United States
| | - Micaël Carrier
- Axe Neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
| | - Marie-Ève Tremblay
- Axe Neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Alberto Cruz-Martín
- Graduate Program for Neuroscience, Boston University, Boston, MA, United States
- Department of Biology, Boston University, Boston, MA, United States
- Neurophotonics Center, Boston University, Boston, MA, United States
- Center for Systems Neuroscience, Boston University, Boston, MA, United States
- Department of Pharmacology and Experimental Therapeutics, Boston University, Boston, MA, United States
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19
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Joost E, Jordão MJC, Mages B, Prinz M, Bechmann I, Krueger M. Microglia contribute to the glia limitans around arteries, capillaries and veins under physiological conditions, in a model of neuroinflammation and in human brain tissue. Brain Struct Funct 2019; 224:1301-1314. [PMID: 30706162 DOI: 10.1007/s00429-019-01834-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/12/2019] [Indexed: 12/23/2022]
Abstract
Microglia represent resident immune cells of the central nervous system (CNS), which have been shown to be involved in the pathophysiology of practically every neuropathology. As microglia were described to participate in the formation of the astroglial glia limitans around CNS vessels, they are part of the neurovascular unit (NVU). Since the NVU is a highly specialized structure, being functionally and morphologically adapted to differing demands in the arterial, capillary, and venous segments, the present study was aimed to systematically investigate the microglial contribution to the glia limitans along the vascular tree. Thereby, the microglial participation in the glia limitans was demonstrated for arteries, capillaries, and veins by immunoelectron microscopy in wild-type mice. Furthermore, analysis by confocal laser scanning microscopy revealed the highest density of microglial endfeet contacting the glial basement membrane around capillaries, with significantly lower densities around arteries and veins. Importantly, this pattern appeared to be unaltered in the setting of experimental autoimmune encephalomyelitis (EAE) in CX3CR1CreERT2:R26-Tomato reporter mice, although perivascular infiltrates of blood-borne leukocytes predominantly occur at the level of post-capillary venules. However, EAE animals exhibited significantly increased contact sizes of individual microglial endfeet around arteries and veins. Noteworthy, under EAE conditions, the upregulation of MHC-II was not limited to microglia of the glia limitans of veins showing infiltrates of leukocytes, but also appeared at the capillary level. As a microglial contribution to the glia limitans was also observed in human brain tissue, these findings may help characterizing microglial alterations within the NVU in various neuropathologies.
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Affiliation(s)
- Emely Joost
- Institute of Anatomy, Leipzig University, Liebigstraße 13, 04103, Leipzig, Germany
| | - Marta J C Jordão
- Institute of Neuropathology, University of Freiburg, Breisacher Straße 64, 79106, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Bianca Mages
- Institute of Anatomy, Leipzig University, Liebigstraße 13, 04103, Leipzig, Germany
| | - Marco Prinz
- Institute of Neuropathology, University of Freiburg, Breisacher Straße 64, 79106, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Liebigstraße 13, 04103, Leipzig, Germany.
| | - Martin Krueger
- Institute of Anatomy, Leipzig University, Liebigstraße 13, 04103, Leipzig, Germany.
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20
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Stewart AN, Kendziorski G, Deak ZM, Bartosek NC, Rezmer BE, Jenrow K, Rossignol J, Dunbar GL. Transplantation of mesenchymal stem cells that overexpress NT-3 produce motor improvements without axonal regeneration following complete spinal cord transections in rats. Brain Res 2018; 1699:19-33. [DOI: 10.1016/j.brainres.2018.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/26/2018] [Accepted: 06/01/2018] [Indexed: 12/22/2022]
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21
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Yin J, Xu W, Ye M, Zhang Y, Wang H, Zhang J, Li Y, Wang Y. Up-regulated basigin-2 in microglia induced by hypoxia promotes retinal angiogenesis. J Cell Mol Med 2017; 21:3467-3480. [PMID: 28661035 PMCID: PMC5706566 DOI: 10.1111/jcmm.13256] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 04/20/2017] [Indexed: 11/29/2022] Open
Abstract
Retinal microglia cells contribute to vascular angiogenesis and vasculopathy induced by relative hypoxia. However, its concrete molecular mechanisms in shaping retinal angiogenesis have not been elucidated. Basigin, being involved in tumour neovasculogenesis, is explored to exert positive effects on retinal angiogenesis induced by microglia. Therefore, we set out to investigate the expression of basigin using a well-characterized mouse model of oxygen-induced retinopathy, which recapitulated hypoxia-induced aberrant neovessel growth. Our results elucidate that basigin is overexpressed in microglia, which accumulating in retinal angiogenic sprouts. In vitro, conditioned media from microglia BV2 under hypoxia treatment increase migration and tube formation of retinal capillary endothelia cells, compared with media from normoxic condition. The angiogenic capacity of BV2 is inhibited after basigin knockdown by small interfering RNAs. A new molecular mechanism for high angiogenic capacity, whereby microglia cells release basigin via up-regulation of PI3K-AKT and IGF-1 pathway to induce angiogenesis is unveiled. Collectively, our results demonstrate that basigin from hypoxic microglia plays a pivotal pro-angiogenic role, providing new insights into microglia-promoting retinal angiogenesis.
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Affiliation(s)
- Jie Yin
- Department of OphthalmologyEye Institute of China PLAXijing HospitalFourth Military Medical UniversityXi'anChina
- Department of OphthalmologyJinling HospitalNanjingChina
| | - Wen‐Qin Xu
- Department of OphthalmologyEye Institute of China PLAXijing HospitalFourth Military Medical UniversityXi'anChina
| | - Ming‐Xiang Ye
- Department of Pulmonary MedicineXijing HospitalFourth Military Medical UniversityXi'anChina
| | - Yong Zhang
- Department of Pulmonary MedicineXijing HospitalFourth Military Medical UniversityXi'anChina
| | - Hai‐Yan Wang
- Department of OphthalmologyEye Institute of China PLAXijing HospitalFourth Military Medical UniversityXi'anChina
| | - Jian Zhang
- Department of Biochemistry and Molecular BiologyFourth Military Medical UniversityXi'anChina
| | - Yu Li
- State Key Laboratory of Cancer BiologyCell Engineering Research Centre & Department of Cell BiologyFourth Military Medical UniversityXi'anChina
| | - Yu‐Sheng Wang
- Department of OphthalmologyEye Institute of China PLAXijing HospitalFourth Military Medical UniversityXi'anChina
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22
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Ontogeny and homeostasis of CNS myeloid cells. Nat Immunol 2017; 18:385-392. [PMID: 28323268 DOI: 10.1038/ni.3703] [Citation(s) in RCA: 292] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/30/2017] [Indexed: 12/12/2022]
Abstract
Myeloid cells in the central nervous system (CNS) represent a heterogeneous class of innate immune cells that contribute to the maintenance of tissue homeostasis differentially during development and adulthood. The subsets of CNS myeloid cells identified so far, including parenchymal microglia and non-parenchymal meningeal, perivascular and choroid-plexus macrophages, as well as disease-associated monocytes, have classically been distinguished on the basis of their surface epitope expression, localization and morphology. However, studies using cell-specific targeting, in vivo imaging, single-cell expression analysis and other sophisticated tools have now increased the depth of knowledge of this immune-cell compartment and call for reevaluation of the traditional views on the origin, fate and function of distinct CNS myeloid subsets. The concepts of CNS macrophage biology that are emerging from these new insights have broad implications for the understanding and treatment of CNS diseases.
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23
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Harrison-Brown M, Liu GJ, Banati R. Checkpoints to the Brain: Directing Myeloid Cell Migration to the Central Nervous System. Int J Mol Sci 2016; 17:E2030. [PMID: 27918464 PMCID: PMC5187830 DOI: 10.3390/ijms17122030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 12/13/2022] Open
Abstract
Myeloid cells are a unique subset of leukocytes with a diverse array of functions within the central nervous system during health and disease. Advances in understanding of the unique properties of these cells have inspired interest in their use as delivery vehicles for therapeutic genes, proteins, and drugs, or as "assistants" in the clean-up of aggregated proteins and other molecules when existing drainage systems are no longer adequate. The trafficking of myeloid cells from the periphery to the central nervous system is subject to complex cellular and molecular controls with several 'checkpoints' from the blood to their destination in the brain parenchyma. As important components of the neurovascular unit, the functional state changes associated with lineage heterogeneity of myeloid cells are increasingly recognized as important for disease progression. In this review, we discuss some of the cellular elements associated with formation and function of the neurovascular unit, and present an update on the impact of myeloid cells on central nervous system (CNS) diseases in the laboratory and the clinic. We then discuss emerging strategies for harnessing the potential of site-directed myeloid cell homing to the CNS, and identify promising avenues for future research, with particular emphasis on the importance of untangling the functional heterogeneity within existing myeloid subsets.
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Affiliation(s)
- Meredith Harrison-Brown
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141, Australia.
- Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia.
| | - Guo-Jun Liu
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141, Australia.
- Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia.
| | - Richard Banati
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141, Australia.
- Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia.
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2006, Australia.
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24
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Filosa JA, Morrison HW, Iddings JA, Du W, Kim KJ. Beyond neurovascular coupling, role of astrocytes in the regulation of vascular tone. Neuroscience 2016; 323:96-109. [PMID: 25843438 PMCID: PMC4592693 DOI: 10.1016/j.neuroscience.2015.03.064] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 03/24/2015] [Accepted: 03/27/2015] [Indexed: 12/22/2022]
Abstract
The brain possesses two intricate mechanisms that fulfill its continuous metabolic needs: cerebral autoregulation, which ensures constant cerebral blood flow over a wide range of arterial pressures and functional hyperemia, which ensures rapid delivery of oxygen and glucose to active neurons. Over the past decade, a number of important studies have identified astrocytes as key intermediaries in neurovascular coupling (NVC), the mechanism by which active neurons signal blood vessels to change their diameter. Activity-dependent increases in astrocytic Ca(2+) activity are thought to contribute to the release of vasoactive substances that facilitate arteriole vasodilation. A number of vasoactive signals have been identified and their role on vessel caliber assessed both in vitro and in vivo. In this review, we discuss mechanisms implicating astrocytes in NVC-mediated vascular responses, limitations encountered as a result of the challenges in maintaining all the constituents of the neurovascular unit intact and deliberate current controversial findings disputing a main role for astrocytes in NVC. Finally, we briefly discuss the potential role of pericytes and microglia in NVC-mediated processes.
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Affiliation(s)
- J A Filosa
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States.
| | - H W Morrison
- University of Arizona, 1305 N. Martin Avenue, P.O. Box 210203, Tucson, AZ 85721, United States
| | - J A Iddings
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States
| | - W Du
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States
| | - K J Kim
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States
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Dudvarski Stankovic N, Teodorczyk M, Ploen R, Zipp F, Schmidt MHH. Microglia-blood vessel interactions: a double-edged sword in brain pathologies. Acta Neuropathol 2016; 131:347-63. [PMID: 26711460 DOI: 10.1007/s00401-015-1524-y] [Citation(s) in RCA: 194] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/09/2015] [Accepted: 12/12/2015] [Indexed: 12/12/2022]
Abstract
Microglia are long-living resident immune cells of the brain, which secure a stable chemical and physical microenvironment necessary for the proper functioning of the central nervous system (CNS). These highly dynamic cells continuously scan their environment for pathogens and possess the ability to react to damage-induced signals in order to protect the brain. Microglia, together with endothelial cells (ECs), pericytes and astrocytes, form the functional blood-brain barrier (BBB), a specialized endothelial structure that selectively separates the sensitive brain parenchyma from blood circulation. Microglia are in bidirectional and permanent communication with ECs and their perivascular localization enables them to survey the influx of blood-borne components into the CNS. Furthermore, they may stimulate the opening of the BBB, extravasation of leukocytes and angiogenesis. However, microglia functioning requires tight control as their dysregulation is implicated in the initiation and progression of numerous neurological diseases. Disruption of the BBB, changes in blood flow, introduction of pathogens in the sensitive CNS niche, insufficient nutrient supply, and abnormal secretion of cytokines or expression of endothelial receptors are reported to prime and attract microglia. Such reactive microglia have been reported to even escalate the damage of the brain parenchyma as is the case in ischemic injuries, brain tumors, multiple sclerosis, Alzheimer's and Parkinson's disease. In this review, we present the current state of the art of the causes and mechanisms of pathological interactions between microglia and blood vessels and explore the possibilities of targeting those dysfunctional interactions for the development of future therapeutics.
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Affiliation(s)
- Nevenka Dudvarski Stankovic
- Molecular Signal Transduction Laboratories, Institute for Microscopic Anatomy and Neurobiology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131, Mainz, Germany.
- German Cancer Consortium (DKTK), Heidelberg, Germany.
- German Cancer Research Center (DKFZ), Heidelberg, Germany.
| | - Marcin Teodorczyk
- Molecular Signal Transduction Laboratories, Institute for Microscopic Anatomy and Neurobiology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131, Mainz, Germany.
| | - Robert Ploen
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Research Center for Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
| | - Frauke Zipp
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Research Center for Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
| | - Mirko H H Schmidt
- Molecular Signal Transduction Laboratories, Institute for Microscopic Anatomy and Neurobiology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131, Mainz, Germany.
- German Cancer Consortium (DKTK), Heidelberg, Germany.
- German Cancer Research Center (DKFZ), Heidelberg, Germany.
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Johnsen KB, Moos T. Revisiting nanoparticle technology for blood–brain barrier transport: Unfolding at the endothelial gate improves the fate of transferrin receptor-targeted liposomes. J Control Release 2016; 222:32-46. [DOI: 10.1016/j.jconrel.2015.11.032] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 11/28/2015] [Accepted: 11/30/2015] [Indexed: 12/25/2022]
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Spanos JP, Hsu NJ, Jacobs M. Microglia are crucial regulators of neuro-immunity during central nervous system tuberculosis. Front Cell Neurosci 2015; 9:182. [PMID: 26041993 PMCID: PMC4435040 DOI: 10.3389/fncel.2015.00182] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/27/2015] [Indexed: 01/11/2023] Open
Abstract
Mycobacterium tuberculosis (M. tuberculosis) infection of the central nervous system (CNS) is the most devastating manifestation of tuberculosis (TB), with both high mortality and morbidity. Although research has been fueled by the potential therapeutic target microglia offer against neurodegenerative inflammation, their part in TB infection of the CNS has not been fully evaluated nor elucidated. Yet, as both the preferential targets of M. tuberculosis and the immune-effector cells of the CNS, microglia are likely to be key determinants of disease severity and clinical outcomes. Following pathogen recognition, bacilli are internalized and capable of replicating within microglia. Cellular activation ensues, utilizing signaling molecules that may be neurotoxic. Central to initiating, orchestrating and modulating the tuberculous immune response is microglial secretion of cytokines and chemokines. However, the neurological environment is unique in that inflammatory signals, which appear to be damaging in the periphery, could be beneficial by governing neuronal survival, regeneration and differentiation. Furthermore, microglia are important in the recruitment of peripheral immune cells and central to defining the pro-inflammatory milieu of which neurotoxicity may result from many of the participating local or recruited cell types. Microglia are capable of both presenting antigen to infiltrating CD4(+) T-lymphocytes and inducing their differentiation-a possible correlate of protection against M. tuberculosis infection. Clarifying the nature of the immune effector molecules secreted by microglia, and the means by which other CNS-specific cell types govern microglial activation or modulate their responses is critical if improved diagnostic and therapeutic strategies are to be attained. Therefore, this review evaluates the diverse roles microglia play in the neuro-immunity to M. tuberculosis infection of the CNS.
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Affiliation(s)
- Jonathan Paul Spanos
- Division of Immunology, Faculty of Health Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town Cape Town, South Africa
| | - Nai-Jen Hsu
- Division of Immunology, Faculty of Health Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town Cape Town, South Africa
| | - Muazzam Jacobs
- Division of Immunology, Faculty of Health Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town Cape Town, South Africa ; National Health Laboratory Service Johannesburg, South Africa
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Nga VDW, Lim J, Choy DKS, Nyein MA, Lu J, Chou N, Yeo TT, Teoh SH. Effects of polycaprolactone-based scaffolds on the blood-brain barrier and cerebral inflammation. Tissue Eng Part A 2015; 21:647-53. [PMID: 25335965 DOI: 10.1089/ten.tea.2013.0779] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Severe pathoanatomical and mechanical injuries compromise patient recovery and survival following penetrating brain injury (PBI). The realization that the blood-brain barrier (BBB) plays a major role in dictating post-PBI events has led to rising interests in possible therapeutic interventions through the BBB. Recently, the choroid plexus has also been suggested as a potential therapeutic target. The use of biocompatible scaffolds for the delivery of therapeutic agents, but little is known about their interaction with cerebral tissue, which has important clinical implications. Therefore, the authors have sought to investigate the effect of polycaprolactone (PCL) and PCL/tricalcium phosphate (PCL/TCP) scaffolds on the maintenance of BBB phenotype posttraumatic brain injury. Cranial defects of 3 mm depth were created in Sprague Dawley rats, and PCL and PCL/TCP scaffolds were subsequently implanted in predetermined locations for a period of 1 week and 1 month. Higher endothelial barrier antigen (EBA) expressions from PCL-based scaffold groups (p>0.05) were found, suggesting slight advantages over the sham group (no scaffold implantation). PCL/TCP scaffold group also expressed EBA to a higher degree (p>0.05) than PCL scaffolds. Importantly, higher capillary count and area as early as 1 week postimplantation suggested lowered ischemia from the PCL/TCP scaffold group as compared with PCL and sham. Evaluation of interlukin-1β expression suggested that the PCL and PCL/TCP scaffolds did not cause prolonged inflammation. BBB transport selectivity was evaluated by the expression of aquaporin-4 (AQP-4). Attenuated expression of AQP-4 in the PCL/TCP group (p<0.05) suggested that PCL/TCP scaffolds altered BBB selectivity to a lower degree as compared with sham and PCL groups, pointing to potential clinical implications in reducing cerebral edema. Taken together, the responses of PCL-based scaffolds with brain tissue suggested safety, and encourages further preclinical evaluation in PBI management with these scaffolds.
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Dubois LG, Campanati L, Righy C, D'Andrea-Meira I, Spohr TCLDSE, Porto-Carreiro I, Pereira CM, Balça-Silva J, Kahn SA, DosSantos MF, Oliveira MDAR, Ximenes-da-Silva A, Lopes MC, Faveret E, Gasparetto EL, Moura-Neto V. Gliomas and the vascular fragility of the blood brain barrier. Front Cell Neurosci 2014; 8:418. [PMID: 25565956 PMCID: PMC4264502 DOI: 10.3389/fncel.2014.00418] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/18/2014] [Indexed: 12/22/2022] Open
Abstract
Astrocytes, members of the glial family, interact through the exchange of soluble factors or by directly contacting neurons and other brain cells, such as microglia and endothelial cells. Astrocytic projections interact with vessels and act as additional elements of the Blood Brain Barrier (BBB). By mechanisms not fully understood, astrocytes can undergo oncogenic transformation and give rise to gliomas. The tumors take advantage of the BBB to ensure survival and continuous growth. A glioma can develop into a very aggressive tumor, the glioblastoma (GBM), characterized by a highly heterogeneous cell population (including tumor stem cells), extensive proliferation and migration. Nevertheless, gliomas can also give rise to slow growing tumors and in both cases, the afflux of blood, via BBB is crucial. Glioma cells migrate to different regions of the brain guided by the extension of blood vessels, colonizing the healthy adjacent tissue. In the clinical context, GBM can lead to tumor-derived seizures, which represent a challenge to patients and clinicians, since drugs used for its treatment must be able to cross the BBB. Uncontrolled and fast growth also leads to the disruption of the chimeric and fragile vessels in the tumor mass resulting in peritumoral edema. Although hormonal therapy is currently used to control the edema, it is not always efficient. In this review we comment the points cited above, considering the importance of the BBB and the concerns that arise when this barrier is affected.
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Affiliation(s)
- Luiz Gustavo Dubois
- Instituto Estadual do Cérebro Paulo Niemeyer, Rua do Rezende Rio de Janeiro, Brazil
| | - Loraine Campanati
- Laboratório de Morfogênese Celular, Instituto de Ciências Biomédicas da, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Cassia Righy
- Instituto Estadual do Cérebro Paulo Niemeyer, Rua do Rezende Rio de Janeiro, Brazil
| | | | | | | | - Claudia Maria Pereira
- Programa de Pós-Graduação em Odontologia, Escola de Ciências da Saúde (ECS), Universidade do Grande Rio (UNIGRANRIO) Duque de Caxias, Brazil
| | - Joana Balça-Silva
- Centro de Neurociência e Biologia Celular, Faculdade de Medicina, Universidade de Coimbra Coimbra, Portugal
| | - Suzana Assad Kahn
- Instituto Estadual do Cérebro Paulo Niemeyer, Rua do Rezende Rio de Janeiro, Brazil
| | - Marcos F DosSantos
- Laboratório de Morfogênese Celular, Instituto de Ciências Biomédicas da, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | | | - Adriana Ximenes-da-Silva
- Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Alagoas, Maceió Alagoas, Brazil
| | - Maria Celeste Lopes
- Centro de Neurociência e Biologia Celular, Faculdade de Medicina, Universidade de Coimbra Coimbra, Portugal
| | - Eduardo Faveret
- Instituto Estadual do Cérebro Paulo Niemeyer, Rua do Rezende Rio de Janeiro, Brazil
| | | | - Vivaldo Moura-Neto
- Instituto Estadual do Cérebro Paulo Niemeyer, Rua do Rezende Rio de Janeiro, Brazil ; Laboratório de Morfogênese Celular, Instituto de Ciências Biomédicas da, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
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Onoda A, Umezawa M, Takeda K, Ihara T, Sugamata M. Effects of maternal exposure to ultrafine carbon black on brain perivascular macrophages and surrounding astrocytes in offspring mice. PLoS One 2014; 9:e94336. [PMID: 24722459 PMCID: PMC3983141 DOI: 10.1371/journal.pone.0094336] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/12/2014] [Indexed: 11/18/2022] Open
Abstract
Perivascular macrophages (PVMs) constitute a subpopulation of resident macrophages in the central nervous system (CNS). They are located at the blood-brain barrier and can contribute to maintenance of brain functions in both health and disease conditions. PVMs have been shown to respond to particle substances administered during the prenatal period, which may alter their phenotype over a long period. We aimed to investigate the effects of maternal exposure to ultrafine carbon black (UfCB) on PVMs and astrocytes close to the blood vessels in offspring mice. Pregnant mice were exposed to UfCB suspension by intranasal instillation on gestational days 5 and 9. Brains were collected from their offspring at 6 and 12 weeks after birth. PVM and astrocyte phenotypes were examined by Periodic Acid Schiff (PAS) staining, transmission electron microscopy and PAS-glial fibrillary acidic protein (GFAP) double staining. PVM granules were found to be enlarged and the number of PAS-positive PVMs was decreased in UfCB-exposed offspring. These results suggested that in offspring, “normal” PVMs decreased in a wide area of the CNS through maternal UfCB exposure. The increase in astrocytic GFAP expression level was closely related to the enlargement of granules in the attached PVMs in offspring. Honeycomb-like structures in some PVM granules and swelling of astrocytic end-foot were observed under electron microscopy in the UfCB group. The phenotypic changes in PVMs and astrocytes indicate that maternal UfCB exposure may result in changes to brain blood vessels and be associated with increased risk of dysfunction and disorder in the offspring brain.
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Affiliation(s)
- Atsuto Onoda
- Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
- Department of Pathology, Tochigi Institute of Clinical Pathology, Nogi, Tochigi, Japan
- * E-mail:
| | - Masakazu Umezawa
- Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
- The Center for Environmental Health Science for the Next Generation, Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Ken Takeda
- Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
- The Center for Environmental Health Science for the Next Generation, Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Tomomi Ihara
- Department of Pathology, Tochigi Institute of Clinical Pathology, Nogi, Tochigi, Japan
| | - Masao Sugamata
- Department of Pathology, Tochigi Institute of Clinical Pathology, Nogi, Tochigi, Japan
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Chodobski A, Zink BJ, Szmydynger-Chodobska J. Blood-brain barrier pathophysiology in traumatic brain injury. Transl Stroke Res 2013; 2:492-516. [PMID: 22299022 DOI: 10.1007/s12975-011-0125-x] [Citation(s) in RCA: 430] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The blood-brain barrier (BBB) is formed by tightly connected cerebrovascular endothelial cells, but its normal function also depends on paracrine interactions between the brain endothelium and closely located glia. There is a growing consensus that brain injury, whether it is ischemic, hemorrhagic, or traumatic, leads to dysfunction of the BBB. Changes in BBB function observed after injury are thought to contribute to the loss of neural tissue and to affect the response to neuroprotective drugs. New discoveries suggest that considering the entire gliovascular unit, rather than the BBB alone, will expand our understanding of the cellular and molecular responses to traumatic brain injury (TBI). This review will address the BBB breakdown in TBI, the role of blood-borne factors in affecting the function of the gliovascular unit, changes in BBB permeability and post-traumatic edema formation, and the major pathophysiological factors associated with TBI that may contribute to post-traumatic dysfunction of the BBB. The key role of neuroinflammation and the possible effect of injury on transport mechanisms at the BBB will also be described. Finally, the potential role of the BBB as a target for therapeutic intervention through restoration of normal BBB function after injury and/or by harnessing the cerebrovascular endothelium to produce neurotrophic growth factors will be discussed.
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Affiliation(s)
- Adam Chodobski
- Neurotrauma and Brain Barriers Research Laboratory, Department of Emergency Medicine, Alpert Medical School of Brown University, Providence, RI 02903, USA
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Khanna A, Kahle KT, Walcott BP, Gerzanich V, Simard JM. Disruption of ion homeostasis in the neurogliovascular unit underlies the pathogenesis of ischemic cerebral edema. Transl Stroke Res 2013; 5:3-16. [PMID: 24323726 DOI: 10.1007/s12975-013-0307-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/22/2013] [Accepted: 11/06/2013] [Indexed: 02/06/2023]
Abstract
Cerebral edema is a major cause of morbidity and mortality following ischemic stroke, but its underlying molecular pathophysiology is incompletely understood. Recent data have revealed the importance of ion flux via channels and transporters expressed in the neurogliovascular unit in the development of ischemia-triggered cytotoxic edema, vasogenic edema, and hemorrhagic conversion. Disruption of homeostatic mechanisms governing cell volume regulation and epithelial/endothelial ion transport due to ischemia-associated energy failure results in the thermodynamically driven re-equilibration of solutes and water across the CSF-blood and blood-brain barriers that ultimately increases the brain's extravascular volume. Additionally, hypoxia, inflammation, and other stress-triggered increases in the functional expression of ion channels and transporters normally expressed at low levels in the neurogliovascular unit cause disruptions in ion homeostasis that contribute to ischemic cerebral edema. Here, we review the pathophysiological significance of several molecular mediators of ion transport expressed in the neurogliovascular unit, including targets of existing FDA-approved drugs, which might be potential nodes for therapeutic intervention.
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Abstract
Microglia are critical nervous system-specific cells influencing brain development, maintenance of the neural environment, response to injury, and repair. They contribute to neuronal proliferation and differentiation, pruning of dying neurons, synaptic remodeling and clearance of debris and aberrant proteins. Colonization of the brain occurs during gestation with an expansion following birth with localization stimulated by programmed neuronal death, synaptic pruning, and axonal degeneration. Changes in microglia phenotype relate to cellular processes including specific neurotransmitter, pattern recognition, or immune-related receptor activation. Upon activation, microglia cells have the capacity to release a number of substances, e.g., cytokines, chemokines, nitric oxide, and reactive oxygen species, which could be detrimental or beneficial to the surrounding cells. With aging, microglia shift their morphology and may display diminished capacity for normal functions related to migration, clearance, and the ability to shift from a pro-inflammatory to an anti-inflammatory state to regulate injury and repair. This shift in microglia potentially contributes to increased susceptibility and neurodegeneration as a function of age. In the current review, information is provided on the colonization of the brain by microglia, the expression of various pattern recognition receptors to regulate migration and phagocytosis, and the shift in related functions that occur in normal aging.
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Affiliation(s)
- G Jean Harry
- National Toxicology Program Laboratory, National Institute of Environmental Health Sciences, MD C1-04, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA.
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34
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Experimental measles encephalitis in Lewis rats: dissemination of infected neuronal cell subtypes. J Neurovirol 2013; 19:461-70. [DOI: 10.1007/s13365-013-0199-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 08/05/2013] [Accepted: 08/09/2013] [Indexed: 12/11/2022]
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The role of microglia and matrix metalloproteinases involvement in neuroinflammation and gliomas. Clin Dev Immunol 2013; 2013:914104. [PMID: 24023566 PMCID: PMC3759277 DOI: 10.1155/2013/914104] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 06/20/2013] [Indexed: 12/31/2022]
Abstract
Matrix metalloproteinases (MMPs) are involved in the pathogenesis of neuroinflammatory diseases (such as multiple sclerosis) as well as in the expansion of malignant gliomas because they facilitate penetration of anatomical barriers (such as the glia limitans) and migration within the neuropil. This review elucidates pathomechanisms and summarizes the current knowledge of the involvement of MMPs in neuroinflammation and glioma, invasion highlighting microglia as major sources of MMPs. The induction of expression, suppression, and multiple pathways of function of MMPs in these scenarios will also be discussed. Understanding the induction and action of MMPs might provide valuable information and reveal attractive targets for future therapeutic strategies.
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36
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Brosnan CF, Raine CS. The astrocyte in multiple sclerosis revisited. Glia 2013; 61:453-65. [DOI: 10.1002/glia.22443] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/02/2012] [Indexed: 12/18/2022]
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Svahn AJ, Graeber MB, Ellett F, Lieschke GJ, Rinkwitz S, Bennett MR, Becker TS. Development of ramified microglia from early macrophages in the zebrafish optic tectum. Dev Neurobiol 2013; 73:60-71. [PMID: 22648905 DOI: 10.1002/dneu.22039] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 05/24/2012] [Accepted: 05/24/2012] [Indexed: 01/11/2023]
Abstract
Microglia, the resident macrophage precursors of the brain, are necessary for the maintenance of tissue homeostasis and activated by a wide range of pathological stimuli. They have a key role in immune and inflammatory responses. Early microglia stem from primitive macrophages, however the transition from early motile forms to the ramified mature resident microglia has not been assayed in real time. In order to provide such an assay, we used zebrafish transgenic lines in which fluorescent reporter expression is driven by the promoter of macrophage expressed gene 1 (mpeg1; Ellet et al. [2011]: Blood 117(4): e49-e56,). This enabled the investigation of the development of these cells in live, intact larvae. We show that microglia develop from highly motile amoeboid cells that are engaged in phagocytosis of apoptotic cell bodies into a microglial cell type that rapidly morphs back and forth between amoeboid and ramified morphologies. These morphing microglia eventually settle into a typical mature ramified morphology. Developing microglia frequently come into contact with blood capillaries in the brain, and also frequently contact each other. Up to 10 days postfertilization, microglia were observed to undergo symmetric division. In the adult optic tectum, the microglia are highly branched, resembling mammalian microglia. In addition, the mpeg1 transgene also labeled highly branched cells in the skin overlying the optic tectum from 8-9 days postfertilization, which likely represent Langerhans cells. Thus, the development of zebrafish microglia and their cellular interactions was studied in the intact developing brain in real time and at cellular resolution.
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Affiliation(s)
- Adam J Svahn
- Brain and Mind Research Institute, Sydney Medical School, University of Sydney, 100 Mallett St., Camperdown, New South Wales 2050, Australia
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Derecki NC, Cronk JC, Kipnis J. The role of microglia in brain maintenance: implications for Rett syndrome. Trends Immunol 2012; 34:144-50. [PMID: 23122051 DOI: 10.1016/j.it.2012.10.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 09/29/2012] [Accepted: 10/02/2012] [Indexed: 12/14/2022]
Abstract
The role of microglia in central nervous system (CNS) pathology has been studied extensively, and more recently, examination of microglia in the healthy brain has yielded important insights into their many functions. It was long assumed that microglia were essentially quiescent cells, unless provoked into activation, which was considered a hallmark of disease. More recently, however, it has become increasingly clear that they are extraordinarily dynamic cells, constantly sampling their environment and adjusting to exquisitely delicate stimuli. Along these lines, our laboratory has identified a new and unexpected role for microglial phagocytosis - or lack thereof - in the pathophysiology of Rett syndrome, a neurodevelopmental disease caused by mutation of the gene encoding methyl-CpG binding protein (MECP)2. We have shown that specific expression of wild type Mecp2 in myeloid cells of Mecp2-null mice is sufficient to arrest major symptoms associated with this devastating disease. This beneficial effect, however, is abolished if phagocytic activity of microglia is inhibited. Here, we discuss microglial origins, the role of microglia in brain development and maintenance, and the phenomenon of microglial augmentation by myeloid progenitor cells in the adult brain. Finally, we address in some detail the beneficial roles of microglia as clinical targets in Rett syndrome and other neurological disorders.
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Affiliation(s)
- Noël C Derecki
- Center for Brain Immunology and Glia and Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA.
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Baeten KM, Akassoglou K. Extracellular matrix and matrix receptors in blood-brain barrier formation and stroke. Dev Neurobiol 2012; 71:1018-39. [PMID: 21780303 DOI: 10.1002/dneu.20954] [Citation(s) in RCA: 267] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The blood-brain barrier (BBB) is formed primarily to protect the brain microenvironment from the influx of plasma components, which may disturb neuronal functions. The BBB is a functional unit that consists mainly of specialized endothelial cells (ECs) lining the cerebral blood vessels, astrocytes, and pericytes. The BBB is a dynamic structure that is altered in neurologic diseases, such as stroke. ECs and astrocytes secrete extracellular matrix (ECM) proteins to generate and maintain the basement membranes (BMs). ECM receptors, such as integrins and dystroglycan, are also expressed at the brain microvasculature and mediate the connections between cellular and matrix components in physiology and disease. ECM proteins and receptors elicit diverse molecular signals that allow cell adaptation to environmental changes and regulate growth and cell motility. The composition of the ECM is altered upon BBB disruption and directly affects the progression of neurologic disease. The purpose of this review is to discuss the dynamic changes of ECM composition and integrin receptor expression that control BBB functions in physiology and pathology.
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Affiliation(s)
- Kim M Baeten
- Gladstone Institute of Neurological Disease, University of California, San Francisco, California 94158, USA
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Harry GJ, Kraft AD. Microglia in the developing brain: a potential target with lifetime effects. Neurotoxicology 2012; 33:191-206. [PMID: 22322212 DOI: 10.1016/j.neuro.2012.01.012] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/24/2012] [Accepted: 01/25/2012] [Indexed: 12/15/2022]
Abstract
Microglia are a heterogenous group of monocyte-derived cells serving multiple roles within the brain, many of which are associated with immune and macrophage like properties. These cells are known to serve a critical role during brain injury and to maintain homeostasis; yet, their defined roles during development have yet to be elucidated. Microglial actions appear to influence events associated with neuronal proliferation and differentiation during development, as well as, contribute to processes associated with the removal of dying neurons or cellular debris and management of synaptic connections. These long-lived cells display changes during injury and with aging that are critical to the maintenance of the neuronal environment over the lifespan of the organism. These processes may be altered by changes in the colonization of the brain or by inflammatory events during development. This review addresses the role of microglia during brain development, both structurally and functionally, as well as the inherent vulnerability of the developing nervous system. A framework is presented considering microglia as a critical nervous system-specific cell that can influence multiple aspects of brain development (e.g., vascularization, synaptogenesis, and myelination) and have a long term impact on the functional vulnerability of the nervous system to a subsequent insult, whether environmental, physical, age-related, or disease-related.
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Affiliation(s)
- G Jean Harry
- National Toxicology Program Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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Nayak D, Zinselmeyer BH, Corps KN, McGavern DB. In vivo dynamics of innate immune sentinels in the CNS. INTRAVITAL 2012; 1:95-106. [PMID: 24078900 PMCID: PMC3784260 DOI: 10.4161/intv.22823] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The innate immune system is comprised of cellular sentinels that often serve as the first responders to injury and invading pathogens. Our basic understanding of innate immunity is derived from research conducted in peripheral lymphoid tissues. However, it is now recognized that most non-lymphoid tissues throughout the body are equipped with specialized innate immune cells that are uniquely adapted to the niches in which they reside. The central nervous system (CNS) is a particularly interesting compartment because it contains a population of post-mitotic cells (neurons) that are intolerant of robust, cytopathic inflammatory responses observed in many peripheral tissues. Thus, evolutionary adaptations have fitted the CNS with a unique array of innate immune sentinels that facilitate the development of local inflammatory responses but attempt to do so in a manner that preserves the integrity of its post-mitotic residents. Interestingly, studies have even suggested that CNS resident innate immune cells contribute to the homeostasis of this compartment and promote neural activity. In this review we discuss recent advances in our understanding of CNS innate immune sentinels and how novel imaging approaches such as intravital two-photon laser scanning microscopy (TPLSM) have shed light on these cells during states of health and disease.
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Affiliation(s)
- Debasis Nayak
- National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda, MD USA
| | - Bernd H. Zinselmeyer
- National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda, MD USA
| | - Kara N. Corps
- National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda, MD USA
| | - Dorian B. McGavern
- National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda, MD USA
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Eilert-Olsen M, Haj-Yasein NN, Vindedal GF, Enger R, Gundersen GA, Hoddevik EH, Petersen PH, Haug FMS, Skare Ø, Adams ME, Froehner SC, Burkhardt JM, Thoren AE, Nagelhus EA. Deletion of aquaporin-4 changes the perivascular glial protein scaffold without disrupting the brain endothelial barrier. Glia 2011; 60:432-40. [PMID: 22131281 DOI: 10.1002/glia.22277] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 11/11/2011] [Indexed: 11/08/2022]
Abstract
Expression of the water channel aquaporin-4 (AQP4) at the blood-brain interface is dependent upon the dystrophin associated protein complex. Here we investigated whether deletion of the Aqp4 gene affects the molecular composition of this protein scaffold and the integrity of the blood-brain barrier. High-resolution immunogold cytochemistry revealed that perivascular expression of α-syntrophin was reduced by 60% in Aqp4(-/-) mice. Additionally, perivascular AQP4 expression was reduced by 88% in α-syn(-/-) mice, in accordance with earlier reports. Immunofluorescence showed that Aqp4 deletion also caused a modest reduction in perivascular dystrophin, whereas β-dystroglycan labeling was unaltered. Perivascular microglia were devoid of AQP4 immunoreactivity. Deletion of Aqp4 did not alter the ultrastructure of capillary endothelial cells, the expression of tight junction proteins (claudin-5, occludin, and zonula occludens 1), or the vascular permeability to horseradish peroxidase and Evans blue albumin dye. We conclude that Aqp4 deletion reduces the expression of perivascular glial scaffolding proteins without affecting the endothelial barrier. Our data also indicate that AQP4 and α-syntrophin are mutually dependent upon each other for proper perivascular expression.
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Affiliation(s)
- Martine Eilert-Olsen
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
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Walsh JT, Kipnis J. Regulatory T cells in CNS injury: the simple, the complex and the confused. Trends Mol Med 2011; 17:541-7. [PMID: 21741881 DOI: 10.1016/j.molmed.2011.05.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 05/21/2011] [Accepted: 05/27/2011] [Indexed: 11/19/2022]
Abstract
Regulatory CD4(+)CD25(+)Foxp3(+) T cells (Tregs) have been the focus of significant attention for their role in controlling immune responses. Although knowledge of Treg biology has burgeoned, wide gaps remain in our understanding of Treg function under both normal and pathological conditions. Pioneering studies demonstrated roles for Tregs in cancer and autoimmune diseases, including experimental autoimmune encephalitis, and this knowledge is often applied to other pathologies including neurodegenerative conditions. However, differences between immunity in neurodegeneration and in malignancy or autoimmunity are often neglected. Thus, Treg manipulations in central nervous system (CNS) neurodegenerative conditions often yield unexpected outcomes. In this piece, we explore how the immunology of neurodegeneration differs from that of cancer and autoimmunity and how these differences create confusion about the role of Tregs in neurodegenerative conditions.
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Affiliation(s)
- James T Walsh
- Neuroscience Graduate Program and Medical Scientist Training Program, Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
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Vojdani A, Lambert J. The Role of Th17 in Neuroimmune Disorders: Target for CAM Therapy. Part II. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2011:984965. [PMID: 19622601 PMCID: PMC3137879 DOI: 10.1093/ecam/nep063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 05/22/2009] [Indexed: 12/23/2022]
Abstract
Decades of research went into understanding the role that Th1 autoreactive T-cells play in neuroinflammation. Here we describe another effector population, the IL-17-producing T-helper lineage (Th17), which drives the inflammatory process. Through the recruitment of inflammatory infiltration neutrophils and the activation of matrix metalloproteinases, IL-17, a cytokine secreted by Th17 cells, contributes to blood-brain barrier breakdown and the subsequent attraction of macrophages and monocytes into the nervous system. The entry of cells along with the local production of inflammatory cytokines leads to myelin and axonal damage. This activation of the inflammatory response system is induced by different pathogenic factors, such as gut bacterial endotoxins resulting in progressive neurodegeneration by Th17 cells. Through the understanding of the role of bacterial endotoxins and other pathogenic factors in the induction of autoimmune diseases by Th17 cells, CAM practitioners will be able to design CAM therapies targeting IL-17 activity. Targeted therapy can restore the integrity of the intestinal and blood-brain barriers using probiotics, N-acetyl-cysteine, α-lipoic acid, resveratrol and others for their patients with autoimmunities, in particular those with neuroinflammation and neurodegeneration.
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CD11c-expressing cells reside in the juxtavascular parenchyma and extend processes into the glia limitans of the mouse nervous system. Acta Neuropathol 2011; 121:445-58. [PMID: 21076838 DOI: 10.1007/s00401-010-0774-y] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 10/27/2010] [Accepted: 10/31/2010] [Indexed: 12/13/2022]
Abstract
Recent studies demonstrated that primary immune responses can be induced within the brain depending on vessel-associated cells expressing markers of dendritic cells (DC). Using mice transcribing the green fluorescent protein (GFP) under the promoter of the DC marker CD11c, we determined the distribution, phenotype, and source of CD11c+ cells in non-diseased brains. Predilection areas of multiple sclerosis (MS) lesions (periventricular area, adjacent fibre tracts, and optical nerve) were preferentially populated by CD11c+ cells. Most CD11c+ cells were located within the juxtavascular parenchyma rather than the perivascular spaces. Virtually all CD11c+ cells co-expressed ionized calcium-binding adaptor molecule 1 (IBA-1), CD11b, while detectable levels of major histocompatibility complex II (MHC-II) in non-diseased mice was restricted to CD11c+ cells of the choroid plexus. Cellular processes project into the glia limitans which may allow transport and/or presentation of intraparenchymal antigens to extravasated T cells in perivascular spaces. In chimeric mice bearing CD11c-GFP bone marrow, fluorescent cells appeared in the CNS between 8 and 12 weeks after transplantation. In organotypic slice cultures from CD11c-GFP mice, the number of fluorescent cells strongly increased within 72 h. Strikingly, using anti-CD209, an established marker for human DC, a similar population was detected in human brains. Thus, we show for the first time that CD11c+ cells can not only be recruited from the blood into the parenchyma, but also develop from an intraneural precursor in situ. Dysbalance in their recruitment/development may be an initial step in the pathogenesis of chronic (autoimmune) neuroinflammatory diseases such as MS.
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Mathiisen TM, Lehre KP, Danbolt NC, Ottersen OP. The perivascular astroglial sheath provides a complete covering of the brain microvessels: an electron microscopic 3D reconstruction. Glia 2010; 58:1094-103. [PMID: 20468051 DOI: 10.1002/glia.20990] [Citation(s) in RCA: 606] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The unravelling of the polarized distribution of AQP4 in perivascular astrocytic endfeet has revitalized the interest in the role of astrocytes in controlling water and ion exchange at the brain-blood interface. The importance of the endfeet is based on the premise that they constitute a complete coverage of the vessel wall. Despite a number of studies based on different microscopic techniques this question has yet to be resolved. We have made an electron microscopic 3D reconstruction of perivascular endfeet in CA1 (stratum moleculare) of rat hippocampus. The endfeet interdigitate and overlap, leaving no slits between them. Only in a few sites do processes--tentatively classified as processes of microglia--extend through the perivascular glial sheath to establish direct contact with the endothelial basal lamina. In contrast to the endfoot covering of the endothelial tube, the endfoot covering of the pericyte is incomplete, allowing neuropil elements to touch the basal lamina that enwraps this type of cell. The 3D reconstruction also revealed large bundles of mitochondria in the endfoot processes that came in close apposition to the perivascular endfoot membrane. Our data support the idea that in pathophysiological conditions, the perivascular astrocytic covering may control the exchange of water and solutes between blood and brain and that free diffusion is limited to narrow clefts between overlapping endfeet.
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Affiliation(s)
- Thomas Misje Mathiisen
- Centre for Molecular Biology and Neuroscience, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway
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Takatsuki H, Taguchi F, Nomura R, Kashiwazaki H, Watanabe M, Ikehara Y, Watanabe R. Cytopathy of an infiltrating monocyte lineage during the early phase of infection with murinecoronavirus in the brain. Neuropathology 2009; 30:361-71. [PMID: 20051016 PMCID: PMC7194124 DOI: 10.1111/j.1440-1789.2009.01082.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Viral spread during the early stages after infection was compared between a highly neurovirulent mouse hepatitis virus (MHV), JHMV cl-2 strain (cl-2), and its low-virulent mutant, soluble-receptor-resistant (srr)7. The infection of cells with srr7 (soluble-receptor-resistant mutant 7) is dependent on a known MHV receptor (MHVR), carcinoembryonic cell adhesion molecule 1a, whereas cl-2 shows MHVR-independent infection. Initial viral antigens were detected between 12 and 24 h post-inoculation (p.i) in the infiltrating cells that appeared in the subarachnoidal space of mouse brains infected with viruses. There were no significant differences in the intensity or spread of viral antigens in the inflammatory cells between the two viruses. However, 48 h after infection with cl-2, viral antigen-positive cells in the grey matter with the shape of neurons, which do not express MHVR, were detected, while srr7 infection was observed primarily in the white matter. Some of the viral antigen-positive inflammatory cells found in the subarachnoidal space during the early phase of infection reacted with anti-F4/80 or anti-CD11b monoclonal antibodies. Syncytial giant cells (SGCs) expressing viral and CD11b antigens were also detected among these inflammatory cells. These antigen-positive cells appeared in the subarachnoidal space prior to viral antigen spread into the brain parenchyma, indicating that viral encephalitis starts with the infection of infiltrating monocytes which express MHVR. Furthermore, the observation indicates that viral infection has cytopathic effects on the monocyte lineage, which plays a critical role in innate immunity, leading to the rapid spread of viruses during the early stage of infection.
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Affiliation(s)
- Hanae Takatsuki
- Department of Bioinformatics, Soka University, Hachioji, Tokyo
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Mathieu P, Battista D, Depino A, Roca V, Graciarena M, Pitossi F. The more you have, the less you get: the functional role of inflammation on neuronal differentiation of endogenous and transplanted neural stem cells in the adult brain. J Neurochem 2009; 112:1368-85. [PMID: 20028453 DOI: 10.1111/j.1471-4159.2009.06548.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The differentiation of neural stem cells toward a neuronal phenotype is determined by the extracellular and intracellular factors that form the neurogenic niche. In this review, we discuss the available data on the functional role of inflammation and in particular, pro- and anti-inflammatory cytokines, on neuronal differentiation from endogenous and transplanted neural stem/progenitor cells. In addition, we discuss the role of microglial cell activation on these processes and the fact that microglial cell activation is not univocally associated with a pro-inflammatory milieu. We conclude that brain cytokines could be regarded as part of the endogenous neurogenic niche. In addition, we propose that accumulating evidence suggests that pro-inflammatory cytokines have a negative effect on neuronal differentiation, while anti-inflammatory cytokines exert an opposite effect. The clarification of the functional role of cytokines on neuronal differentiation will be relevant not only to better understand adult neurogenesis, but also to envisage complementary treatments to modulate cytokine action that could increase the therapeutic benefit of future progenitor/stem cell-based therapies.
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Affiliation(s)
- Patricia Mathieu
- Institute Leloir Foundation-IIBBA-CONICET, Buenos Aires, Argentina
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49
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Ivey NS, MacLean AG, Lackner AA. Acquired immunodeficiency syndrome and the blood-brain barrier. J Neurovirol 2009; 15:111-22. [PMID: 19306229 DOI: 10.1080/13550280902769764] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The blood-brain barrier (BBB) plays a critical role in normal physiology of the central nervous system by regulating what reaches the brain from the periphery. The BBB also plays a major role in neurologic disease including neuropathologic sequelae associated with infection by human immunodeficiency virus (HIV) in humans and the closely related simian immunodeficiency virus (SIV) in macaques. In this review, we provide an overview of the function, structure, and components of the BBB, followed by a more detailed discussion of the subcellular structures and regulation of the tight junction. We then discuss the ways in which HIV/SIV affects the BBB, largely through infection of monocytes/macrophages, and how infected macrophages crossing the BBB ultimately results in breakdown of the barrier.
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Affiliation(s)
- Nathan S Ivey
- Tulane National Primate Research Center, Covington, LA 70433, USA
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50
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Yang P, Das PK, Kijlstra A. Localization and characterization of immunocompetent cells in the human retina. Ocul Immunol Inflamm 2009. [DOI: 10.1076/0927-3948(200009)831-kft149] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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