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Yao Y, Chen Y, Tomer R, Silver R. Capillary connections between sensory circumventricular organs and adjacent parenchyma enable local volume transmission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605849. [PMID: 39211092 PMCID: PMC11361043 DOI: 10.1101/2024.07.30.605849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Among contributors to diffusible signaling are portal systems which join two capillary beds through connecting veins (Dorland 2020). Portal systems allow diffusible signals to be transported in high concentrations directly from one capillary bed to the other without dilution in the systemic circulation. Two portal systems have been identified in the brain. The first was discovered almost a century ago and connects the median eminence to the anterior pituitary gland (Popa & Fielding 1930). The second was discovered a few years ago, and links the suprachiasmatic nucleus to the organum vasculosum of the lamina terminalis, a sensory circumventricular organ (CVO) (Yao et al. 2021). Sensory CVOs bear neuronal receptors for sensing signals in the fluid milieu (McKinley et al. 2003). They line the surface of brain ventricles and bear fenestrated capillaries, thereby lacking blood brain barriers. It is not known whether the other sensory CVOs, namely the subfornical organ (SFO), and area postrema (AP) form portal neurovascular connections with nearby parenchymal tissue. This has been difficult to establish as the structures lie at the midline and protrude into the ventricular space. To preserve the integrity of the vasculature of CVOs and their adjacent neuropil, we combined iDISCO clearing and light-sheet microscopy to acquire volumetric images of blood vessels. The results indicate that there is a portal pathway linking the capillary vessels of the SFO and the posterior septal nuclei, namely the septofimbrial nucleus and the triangular nucleus of the septum. Unlike the latter arrangement, the AP and the nucleus of the solitary tract share their capillary beds. Taken together, the results reveal that all three sensory circumventricular organs bear specialized capillary connections to adjacent neuropil, providing a direct route for diffusible signals to travel from their source to their targets.
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2
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Shen K, Shi Y, Wang X, Leung SW. Cellular Components of the Blood-Brain Barrier and Their Involvement in Aging-Associated Cognitive Impairment. Aging Dis 2024:AD.202.0424. [PMID: 39122454 DOI: 10.14336/ad.202.0424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Accepted: 07/01/2024] [Indexed: 08/12/2024] Open
Abstract
Human life expectancy has been significantly extended, which poses major challenges to our healthcare and social systems. Aging-associated cognitive impairment is attributed to endothelial dysfunction in the cardiovascular system and neurological dysfunction in the central nervous system. The central nervous system is considered an immune-privileged tissue due to the exquisite protection provided by the blood-brain barrier. The present review provides an overview of the structure and function of blood-brain barrier, extending the cell components of blood-brain barrier from endothelial cells and pericytes to astrocytes, perivascular macrophages and oligodendrocyte progenitor cells. In particular, the pathological changes in the blood-brain barrier in aging, with special focus on the underlying mechanisms and molecular changes, are presented. Furthermore, the potential preventive/therapeutic strategies against aging-associated blood-brain barrier disruption are discussed.
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Affiliation(s)
- Kaiyuan Shen
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yi Shi
- Institute of Clinical Science, Zhongshan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Organ Transplantation, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xin Wang
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Susan Ws Leung
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
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3
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Muzio L, Perego J. CNS Resident Innate Immune Cells: Guardians of CNS Homeostasis. Int J Mol Sci 2024; 25:4865. [PMID: 38732082 PMCID: PMC11084235 DOI: 10.3390/ijms25094865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 04/22/2024] [Accepted: 04/25/2024] [Indexed: 05/13/2024] Open
Abstract
Although the CNS has been considered for a long time an immune-privileged organ, it is now well known that both the parenchyma and non-parenchymal tissue (meninges, perivascular space, and choroid plexus) are richly populated in resident immune cells. The advent of more powerful tools for multiplex immunophenotyping, such as single-cell RNA sequencing technique and upscale multiparametric flow and mass spectrometry, helped in discriminating between resident and infiltrating cells and, above all, the different spectrum of phenotypes distinguishing border-associated macrophages. Here, we focus our attention on resident innate immune players and their primary role in both CNS homeostasis and pathological neuroinflammation and neurodegeneration, two key interconnected aspects of the immunopathology of multiple sclerosis.
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Affiliation(s)
- Luca Muzio
- Neuroimmunology Lab, IRCCS San Raffaele Scientific Institute, Institute of Experimental Neurology, 20133 Milan, Italy;
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Singh S, Paul D, Nath V, A R. Exosomes: current knowledge and future perspectives. Tissue Barriers 2024; 12:2232248. [PMID: 37439246 PMCID: PMC11042064 DOI: 10.1080/21688370.2023.2232248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 06/27/2023] [Indexed: 07/14/2023] Open
Abstract
Exosomes are membrane-bound micro-vesicles that possess endless therapeutic potential for treatment of numerous pathologies including autoimmune, cardiovascular, ocular, and nervous disorders. Despite considerable knowledge about exosome biogenesis and secretion, still, there is a lack of information regarding exosome uptake by cell types and internal signaling pathways through which these exosomes process cellular response. Exosomes are key components of cell signaling and intercellular communication. In central nervous system (CNS), exosomes can penetrate BBB and maintain homeostasis by myelin sheath regulation and the waste products elimination. Therefore, the current review summarizes role of exosomes and their use as biomarkers in cardiovascular, nervous and ocular disorders. This aspect of exosomes provides positive hope to monitor disease development and enable early diagnosis and treatment optimization. In this review, we have summarized recent findings on physiological and therapeutic effects of exosomes and also attempt to provide insights about stress-preconditioned exosomes and stem cell-derived exosomes.
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Affiliation(s)
- Swati Singh
- College of Pharmacy, JSS Academy of Technical Sciences, Noida, Uttar Pradesh, India
| | - Deepraj Paul
- College of Pharmacy, JSS Academy of Technical Sciences, Noida, Uttar Pradesh, India
| | - Virendra Nath
- Department of Pharmacy, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, Ajmer, India
| | - Rohini A
- College of Pharmacy, JSS Academy of Technical Sciences, Noida, Uttar Pradesh, India
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5
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Uchikawa H, Uekawa K, Hasegawa Y. Perivascular macrophages in cerebrovascular diseases. Exp Neurol 2024; 374:114680. [PMID: 38185314 DOI: 10.1016/j.expneurol.2024.114680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 12/10/2023] [Accepted: 01/02/2024] [Indexed: 01/09/2024]
Abstract
Cerebrovascular diseases are a major cause of stroke and dementia, both requiring long-term care. These diseases involve multiple pathophysiologies, with mitochondrial dysfunction being a crucial contributor to the initiation of inflammation, apoptosis, and oxidative stress, resulting in injuries to neurovascular units that include neuronal cell death, endothelial cell death, glial activation, and blood-brain barrier disruption. To maintain brain homeostasis against these pathogenic conditions, brain immune cells, including border-associated macrophages and microglia, play significant roles as brain innate immunity cells in the pathophysiology of cerebrovascular injury. Although microglia have long been recognized as significant contributors to neuroinflammation, attention has recently shifted to border-associated macrophages, such as perivascular macrophages (PVMs), which have been studied based on their crucial roles in the brain. These cells are strategically positioned around the walls of brain vessels, where they mainly perform critical functions, such as perivascular drainage, cerebrovascular flexibility, phagocytic activity, antigen presentation, activation of inflammatory responses, and preservation of blood-brain barrier integrity. Although PVMs act as scavenger and surveillant cells under normal conditions, these cells exert harmful effects under pathological conditions. PVMs detect mitochondrial dysfunction in injured cells and implement pathological changes to regulate brain homeostasis. Therefore, PVMs are promising as they play a significant role in mitochondrial dysfunction and, in turn, disrupt the homeostatic condition. Herein, we summarize the significant roles of PVMs in cerebrovascular diseases, especially ischemic and hemorrhagic stroke and dementia, mainly in correlation with inflammation. A better understanding of the biology and pathobiology of PVMs may lead to new insights on and therapeutic strategies for cerebrovascular diseases.
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Affiliation(s)
- Hiroki Uchikawa
- Department of Translational Neuroscience, Barrow Aneurysm and AVM Research Center, Barrow Neurological Institute, Phoenix, AZ, USA; Department of Neurosurgery, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan
| | - Ken Uekawa
- Department of Neurosurgery, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan
| | - Yu Hasegawa
- Department of Pharmaceutical Science, School of Pharmacy at Fukuoka, International University of Health and Welfare, Okawa, Fukuoka, Japan.
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6
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Kaur J, Boyd ED, Ding G, Zhang L, Luo H, Li Q, Li L, Wei M, Landschoot-Ward J, Chopp M, Zhang Z, Jiang Q. The Association between Glymphatic System and Perivascular Macrophages in Brain Waste Clearance. Diagnostics (Basel) 2024; 14:731. [PMID: 38611644 PMCID: PMC11011895 DOI: 10.3390/diagnostics14070731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 04/14/2024] Open
Abstract
The glymphatic system suggests the convective bulk flow of cerebrospinal fluid (CSF) through perivascular spaces and the interstitial spaces of the brain parenchyma for the rapid removal of toxic waste solutes from the brain. However, the presence of convective bulk flow within the brain interstitial spaces is still under debate. We first addressed this argument to determine the involvement of the glymphatic system in brain waste clearance utilizing contrast-enhanced 3D T1-weighted imaging (T1WI), diffusion tensor imaging (DTI), and confocal microscopy imaging. Furthermore, perivascular macrophages (PVMs), which are immune cells located within perivascular spaces, have not been thoroughly explored for their association with the glymphatic system. Therefore, we investigated tracer uptake by PVMs in the perivascular spaces of both the arteries/arterioles and veins/venules and the potential association of PVMs in assisting the glymphatic system for interstitial waste clearance. Our findings demonstrated that both convective bulk flow and diffusion are responsible for the clearance of interstitial waste solutes from the brain parenchyma. Furthermore, our results suggested that PVMs may play an important function in glymphatic system-mediated interstitial waste clearance. The glymphatic system and PVMs could be targeted to enhance interstitial waste clearance in patients with waste-associated neurological conditions and aging.
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Affiliation(s)
- Jasleen Kaur
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physics, Oakland University, Rochester, MI 48309, USA
| | - Edward D. Boyd
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
| | - Guangliang Ding
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
| | - Li Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
| | - Hao Luo
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Qingjiang Li
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Lian Li
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Min Wei
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Julie Landschoot-Ward
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
| | - Michael Chopp
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physics, Oakland University, Rochester, MI 48309, USA
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
- Department of Neurology, Wayne State University, Detroit, MI 48202, USA
| | - Zhenggang Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
- Department of Neurology, Wayne State University, Detroit, MI 48202, USA
| | - Quan Jiang
- Department of Neurology, Henry Ford Health System, Detroit, MI 48202, USA; (J.K.); (E.D.B.); (G.D.); (L.Z.); (H.L.); (Q.L.); (L.L.); (M.W.); (J.L.-W.); (M.C.); (Z.Z.)
- Department of Physics, Oakland University, Rochester, MI 48309, USA
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
- Department of Neurology, Wayne State University, Detroit, MI 48202, USA
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7
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Denes A, Hansen CE, Oezorhan U, Figuerola S, de Vries HE, Sorokin L, Planas AM, Engelhardt B, Schwaninger M. Endothelial cells and macrophages as allies in the healthy and diseased brain. Acta Neuropathol 2024; 147:38. [PMID: 38347307 PMCID: PMC10861611 DOI: 10.1007/s00401-024-02695-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/19/2024] [Accepted: 01/20/2024] [Indexed: 02/15/2024]
Abstract
Diseases of the central nervous system (CNS) are often associated with vascular disturbances or inflammation and frequently both. Consequently, endothelial cells and macrophages are key cellular players that mediate pathology in many CNS diseases. Macrophages in the brain consist of the CNS-associated macrophages (CAMs) [also referred to as border-associated macrophages (BAMs)] and microglia, both of which are close neighbours or even form direct contacts with endothelial cells in microvessels. Recent progress has revealed that different macrophage populations in the CNS and a subset of brain endothelial cells are derived from the same erythromyeloid progenitor cells. Macrophages and endothelial cells share several common features in their life cycle-from invasion into the CNS early during embryonic development and proliferation in the CNS, to their demise. In adults, microglia and CAMs have been implicated in regulating the patency and diameter of vessels, blood flow, the tightness of the blood-brain barrier, the removal of vascular calcification, and the life-time of brain endothelial cells. Conversely, CNS endothelial cells may affect the polarization and activation state of myeloid populations. The molecular mechanisms governing the pas de deux of brain macrophages and endothelial cells are beginning to be deciphered and will be reviewed here.
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Affiliation(s)
- Adam Denes
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Cathrin E Hansen
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Amsterdam UMC, Amsterdam, The Netherlands
- MS Center Amsterdam, Amsterdam UMC Location VU Medical Center, Amsterdam, The Netherlands
| | - Uemit Oezorhan
- Institute of Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany
| | - Sara Figuerola
- Department of Neuroscience and Experimental Therapeutics, Instituto de Investigaciones Biomedicas de Barcelona (IIBB), Consejo Superior de Investigaciones Cientificas (CSIC), 08036, Barcelona, Spain
- Cerebrovascular Research Group, Institut d'Investigacions Biomediques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
- Faculty of Medicine, University of Barcelona, Barcelona, Spain
| | - Helga E de Vries
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Amsterdam UMC, Amsterdam, The Netherlands
- MS Center Amsterdam, Amsterdam UMC Location VU Medical Center, Amsterdam, The Netherlands
| | - Lydia Sorokin
- Institute of Physiological Chemistry and Pathobiochemistry, University of Muenster, Munster, Germany
- Cells-in-Motion Interfaculty Centre (CIMIC), University of Münster, Münster, Germany
| | - Anna M Planas
- Department of Neuroscience and Experimental Therapeutics, Instituto de Investigaciones Biomedicas de Barcelona (IIBB), Consejo Superior de Investigaciones Cientificas (CSIC), 08036, Barcelona, Spain
- Cerebrovascular Research Group, Institut d'Investigacions Biomediques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
- Faculty of Medicine, University of Barcelona, Barcelona, Spain
| | | | - Markus Schwaninger
- Institute of Experimental and Clinical Pharmacology and Toxicology, Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany.
- German Research Centre for Cardiovascular Research (DZHK), Partner Site Hamburg, Lübeck, Kiel, Germany.
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8
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Lund H, Hunt MA, Kurtović Z, Sandor K, Kägy PB, Fereydouni N, Julien A, Göritz C, Vazquez-Liebanas E, Andaloussi Mäe M, Jurczak A, Han J, Zhu K, Harris RA, Lampa J, Graversen JH, Etzerodt A, Haglund L, Yaksh TL, Svensson CI. CD163+ macrophages monitor enhanced permeability at the blood-dorsal root ganglion barrier. J Exp Med 2024; 221:e20230675. [PMID: 38117255 PMCID: PMC10733632 DOI: 10.1084/jem.20230675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/04/2023] [Accepted: 11/27/2023] [Indexed: 12/21/2023] Open
Abstract
In dorsal root ganglia (DRG), macrophages reside close to sensory neurons and have largely been explored in the context of pain, nerve injury, and repair. However, we discovered that most DRG macrophages interact with and monitor the vasculature by sampling macromolecules from the blood. Characterization of the DRG vasculature revealed a specialized endothelial bed that transformed in molecular, structural, and permeability properties along the arteriovenous axis and was covered by macrophage-interacting pericytes and fibroblasts. Macrophage phagocytosis spatially aligned with peak endothelial permeability, a process regulated by enhanced caveolar transcytosis in endothelial cells. Profiling the DRG immune landscape revealed two subsets of perivascular macrophages with distinct transcriptome, turnover, and function. CD163+ macrophages self-maintained locally, specifically participated in vasculature monitoring, displayed distinct responses during peripheral inflammation, and were conserved in mouse and man. Our work provides a molecular explanation for the permeability of the blood-DRG barrier and identifies an unappreciated role of macrophages as integral components of the DRG-neurovascular unit.
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Affiliation(s)
- Harald Lund
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Matthew A. Hunt
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Zerina Kurtović
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
- Kancera AB, Karolinska Institutet Science Park, Stockholm, Sweden
| | - Katalin Sandor
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Paul B. Kägy
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Noah Fereydouni
- Department of Medicine, Rheumatology Unit, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Anais Julien
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Christian Göritz
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Elisa Vazquez-Liebanas
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Maarja Andaloussi Mäe
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Alexandra Jurczak
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Jinming Han
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Keying Zhu
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Robert A. Harris
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Jon Lampa
- Department of Medicine, Rheumatology Unit, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | | | - Anders Etzerodt
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lisbet Haglund
- Division of Orthopaedic Surgery, Department of Surgery, McGill University, Montreal, Canada
| | - Tony L. Yaksh
- Department of Anesthesiology, University of California, San Diego, CA, USA
| | - Camilla I. Svensson
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
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9
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Wen W, Cheng J, Tang Y. Brain perivascular macrophages: current understanding and future prospects. Brain 2024; 147:39-55. [PMID: 37691438 PMCID: PMC10766266 DOI: 10.1093/brain/awad304] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/28/2023] [Accepted: 08/07/2023] [Indexed: 09/12/2023] Open
Abstract
Brain perivascular macrophages are specialized populations of macrophages that reside in the space around cerebral vessels, such as penetrating arteries and venules. With the help of cutting-edge technologies, such as cell fate mapping and single-cell multi-omics, their multifaceted, pivotal roles in phagocytosis, antigen presentation, vascular integrity maintenance and metabolic regulation have more recently been further revealed under physiological conditions. Accumulating evidence also implies that perivascular macrophages are involved in the pathogenesis of neurodegenerative disease, cerebrovascular dysfunction, autoimmune disease, traumatic brain injury and epilepsy. They can act in either protective or detrimental ways depending on the disease course and stage. However, the underlying mechanisms of perivascular macrophages remain largely unknown. Therefore, we highlight potential future directions in research on perivascular macrophages, including the utilization of genetic mice and novel therapeutic strategies that target these unique immune cells for neuroprotective purposes. In conclusion, this review provides a comprehensive update on the current knowledge of brain perivascular macrophages, shedding light on their pivotal roles in central nervous system health and disease.
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Affiliation(s)
- Wenjie Wen
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan 528200, China
| | - Jinping Cheng
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan 528200, China
| | - Yamei Tang
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan 528200, China
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10
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Sosa MJ, Shih AY, Bonney SK. The elusive brain perivascular fibroblast: a potential role in vascular stability and homeostasis. Front Cardiovasc Med 2023; 10:1283434. [PMID: 38075961 PMCID: PMC10704358 DOI: 10.3389/fcvm.2023.1283434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 11/10/2023] [Indexed: 01/09/2024] Open
Abstract
In the brain, perivascular fibroblasts (PVFs) reside within the perivascular spaces (PVSs) of arterioles and large venules, however their physiological and pathophysiological roles remain largely unknown. PVFs express numerous extracellular matrix proteins that are found in the basement membrane and PVS surrounding large diameter vessels. PVFs are sandwiched between the mural cell layer and astrocytic endfeet, where they are poised to interact with mural cells, perivascular macrophages, and astrocytes. We draw connections between the more well-studied PVF pro-fibrotic response in ischemic injury and the less understood thickening of the vascular wall and enlargement of the PVS described in dementia and neurodegenerative diseases. We postulate that PVFs may be responsible for stability and homeostasis of the brain vasculature, and may also contribute to changes within the PVS during disease.
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Affiliation(s)
- Maria J. Sosa
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Andy Y. Shih
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Stephanie K. Bonney
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, United States
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11
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Silvin A, Qian J, Ginhoux F. Brain macrophage development, diversity and dysregulation in health and disease. Cell Mol Immunol 2023; 20:1277-1289. [PMID: 37365324 PMCID: PMC10616292 DOI: 10.1038/s41423-023-01053-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/01/2023] [Indexed: 06/28/2023] Open
Abstract
Brain macrophages include microglia in the parenchyma, border-associated macrophages in the meningeal-choroid plexus-perivascular space, and monocyte-derived macrophages that infiltrate the brain under various disease conditions. The vast heterogeneity of these cells has been elucidated over the last decade using revolutionary multiomics technologies. As such, we can now start to define these various macrophage populations according to their ontogeny and their diverse functional programs during brain development, homeostasis and disease pathogenesis. In this review, we first outline the critical roles played by brain macrophages during development and healthy aging. We then discuss how brain macrophages might undergo reprogramming and contribute to neurodegenerative disorders, autoimmune diseases, and glioma. Finally, we speculate about the most recent and ongoing discoveries that are prompting translational attempts to leverage brain macrophages as prognostic markers or therapeutic targets for diseases that affect the brain.
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Affiliation(s)
- Aymeric Silvin
- INSERM U1015, Gustave Roussy Cancer Campus, Villejuif, 94800, France
| | - Jiawen Qian
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Florent Ginhoux
- INSERM U1015, Gustave Roussy Cancer Campus, Villejuif, 94800, France.
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, 138648, Republic of Singapore.
- Translational Immunology Institute, SingHealth Duke-NUS Academic Medical Centre, Singapore, 169856, Singapore.
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12
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Kaur J, Boyd E, Ding G, Zhang L, Luo H, Li Q, Li L, Wei M, Landschoot-Ward J, Chopp M, Zhang Z, Jiang Q. The Association between Glymphatic System and Perivascular Macrophages in Brain Waste Clearance. RESEARCH SQUARE 2023:rs.3.rs-3390074. [PMID: 37886481 PMCID: PMC10602168 DOI: 10.21203/rs.3.rs-3390074/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The glymphatic system suggests the convective bulk flow of cerebrospinal fluid (CSF) through perivascular spaces and the interstitial spaces of the brain parenchyma for the rapid removal of toxic waste solutes from the brain. However, the presence of convective bulk flow within the brain interstitial spaces is still under debate. We first addressed this argument to determine the involvement of the glymphatic system in brain waste clearance utilizing contrast-enhanced 3D T1-weighted imaging (T1WI), diffusion tensor imaging (DTI), and confocal microscopy imaging. Furthermore, perivascular macrophages (PVMs), which are immune cells located within perivascular spaces, have not been thoroughly explored for their association with the glymphatic system. Therefore, we investigated tracer uptake by PVMs in the perivascular spaces of both the arteries/arterioles and veins/venules and the potential association of PVMs in assisting the glymphatic system for interstitial waste clearance. Our findings demonstrated that both convective bulk flow and diffusion are responsible for the clearance of interstitial waste solutes from the brain parenchyma. Furthermore, our results suggested that PVMs play an important function in glymphatic system-mediated interstitial waste clearance. The glymphatic system and PVMs could be targeted to enhance interstitial waste clearance in patients with waste-associated neurological conditions and aging.
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Affiliation(s)
- Jasleen Kaur
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physics, Oakland University, Rochester, MI, USA
| | - Edward Boyd
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Radiology, Michigan State University, Lasing, MI, USA
| | - Guangliang Ding
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Radiology, Michigan State University, Lasing, MI, USA
| | - Li Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physiology, Michigan State University, Lasing, MI, USA
| | - Hao Luo
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Qingjiang Li
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Lian Li
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Min Wei
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | | | - Michael Chopp
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physics, Oakland University, Rochester, MI, USA
- Department of Physiology, Michigan State University, Lasing, MI, USA
- Department of Neurology, Wayne State University, Detroit, MI, USA
| | - Zhenggang Zhang
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physiology, Michigan State University, Lasing, MI, USA
- Department of Neurology, Wayne State University, Detroit, MI, USA
| | - Quan Jiang
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
- Department of Physics, Oakland University, Rochester, MI, USA
- Department of Radiology, Michigan State University, Lasing, MI, USA
- Department of Neurology, Wayne State University, Detroit, MI, USA
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13
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Goertz JE, Garcia-Bonilla L, Iadecola C, Anrather J. Immune compartments at the brain's borders in health and neurovascular diseases. Semin Immunopathol 2023; 45:437-449. [PMID: 37138042 PMCID: PMC10279585 DOI: 10.1007/s00281-023-00992-6] [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: 02/07/2023] [Accepted: 03/14/2023] [Indexed: 05/05/2023]
Abstract
Recent evidence implicates cranial border immune compartments in the meninges, choroid plexus, circumventricular organs, and skull bone marrow in several neuroinflammatory and neoplastic diseases. Their pathogenic importance has also been described for cardiovascular diseases such as hypertension and stroke. In this review, we will examine the cellular composition of these cranial border immune niches, the potential pathways through which they might interact, and the evidence linking them to cardiovascular disease.
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Affiliation(s)
- Jennifer E Goertz
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61St Street; RR-405, New York, NY, 10065, USA
| | - Lidia Garcia-Bonilla
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61St Street; RR-405, New York, NY, 10065, USA
| | - Costantino Iadecola
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61St Street; RR-405, New York, NY, 10065, USA
| | - Josef Anrather
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61St Street; RR-405, New York, NY, 10065, USA.
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14
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Chen S, Li J, Meng S, He T, Shi Z, Wang C, Wang Y, Cao H, Huang Y, Zhang Y, Gong Y, Gao Y. Microglia and macrophages in the neuro-glia-vascular unit: From identity to functions. Neurobiol Dis 2023; 179:106066. [PMID: 36889483 DOI: 10.1016/j.nbd.2023.106066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Although both are myeloid cells located surrounding cerebral vasculature, vessel-associated microglia (VAM) and perivascular macrophages (PVMs) can be distinguished by their distinct morphologies, signatures and microscopic location. As key component of neuro-glia-vascular unit (NGVU), they play prominent roles in neurovasculature development and pathological process of various central nervous system (CNS) diseases, including phagocytosis, angiogenesis, vessel damage/protection and blood flow regulation, therefore serving as potential targets for therapeutics of a broad array of CNS diseases. Herein, we will provide a comprehensive overview of heterogeneity of VAM/PVMs, highlight limitations of current understanding in this field, and discuss possible directions of future investigations.
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Affiliation(s)
- Shuning Chen
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Jiaying Li
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Shan Meng
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Tingyu He
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Ziyu Shi
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Chenran Wang
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yana Wang
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Hui Cao
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yichen Huang
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yue Zhang
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Ye Gong
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China.
| | - Yanqin Gao
- Department of Critical Care Medicine of Huashan Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, China.
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15
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McArthur S. Regulation of Physiological Barrier Function by the Commensal Microbiota. Life (Basel) 2023; 13:life13020396. [PMID: 36836753 PMCID: PMC9964120 DOI: 10.3390/life13020396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/27/2023] [Accepted: 01/29/2023] [Indexed: 02/04/2023] Open
Abstract
A fundamental characteristic of living organisms is their ability to separate the internal and external environments, a function achieved in large part through the different physiological barrier systems and their component junctional molecules. Barrier integrity is subject to multiple influences, but one that has received comparatively little attention to date is the role of the commensal microbiota. These microbes, which represent approximately 50% of the cells in the human body, are increasingly recognized as powerful physiological modulators in other systems, but their role in regulating barrier function is only beginning to be addressed. Through comparison of the impact commensal microbes have on cell-cell junctions in three exemplar physiological barriers-the gut epithelium, the epidermis and the blood-brain barrier-this review will emphasize the important contribution microbes and microbe-derived mediators play in governing barrier function. By extension, this will highlight the critical homeostatic role of commensal microbes, as well as identifying the puzzles and opportunities arising from our steadily increasing knowledge of this aspect of physiology.
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Affiliation(s)
- Simon McArthur
- Institute of Dentistry, Faculty of Medicine & Dentistry, Queen Mary University of London, Blizard Institute, 4, Newark Street, London E1 2AT, UK
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16
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Gerganova G, Riddell A, Miller AA. CNS border-associated macrophages in the homeostatic and ischaemic brain. Pharmacol Ther 2022; 240:108220. [PMID: 35667516 DOI: 10.1016/j.pharmthera.2022.108220] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 05/17/2022] [Accepted: 05/31/2022] [Indexed: 12/14/2022]
Abstract
CNS border-associated macrophages (BAMs) are a small population of specialised macrophages localised in the choroid plexus, meningeal and perivascular spaces. Until recently, the function of this elusive cell type was poorly understood and largely overlooked, especially in comparison to microglia, the primary brain resident immune cell. However, the recent single cell immunophenotyping or transcriptomic analysis of BAM subsets in the homeostatic brain, coupled with the rapid emergence of new studies exploring BAM functions in various cerebral pathologies, including Alzheimer's disease, hypertension-induced neurovascular and cognitive dysfunction, and ischaemic stroke, has unveiled previously unrecognised heterogeneity and spatial-temporal complexity in BAM populations as well as their contributions to brain homeostasis and disease. In this review, we discuss the implications of this new-found knowledge on our current understanding of BAM function in ischaemic stroke. We first provide a comprehensive overview and discussion of the cell-surface expression profiles, transcriptional signatures and potential functional phenotypes of homeostatic BAM subsets described in recent studies. Evidence for their putative physiological roles is examined, including their involvement in immunological surveillance, waste clearance, and vascular permeability. We discuss the evidence supporting the accumulation and genetic transformation of BAMs in response to ischaemia and appraise the experimental evidence that BAM function might be deleterious in the acute phase of stroke, while considering the mechanisms by which BAMs may influence stroke outcomes in the longer term. Finally, we review the therapeutic potential of immunomodulatory strategies as an approach to stroke management, highlighting current challenges in the field and key issues relating to BAMs, and how BAMs could be harnessed experimentally to support future translational research.
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Affiliation(s)
- Gabriela Gerganova
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Alexandra Riddell
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Alyson A Miller
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow G12 8TA, United Kingdom.
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17
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Mundt S, Greter M, Becher B. The CNS mononuclear phagocyte system in health and disease. Neuron 2022; 110:3497-3512. [PMID: 36327896 DOI: 10.1016/j.neuron.2022.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/21/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022]
Abstract
CNS-resident macrophages-including parenchymal microglia and border-associated macrophages (BAMs)-contribute to neuronal development and health, vascularization, and tissue integrity at steady state. Border-patrolling mononuclear phagocytes such as dendritic cells and monocytes confer important immune functions to the CNS, protecting it from pathogenic threats including aberrant cell growth and brain malignancies. Even though we have learned much about the contribution of lymphocytes to CNS pathologies, a better understanding of differential roles of tissue-resident and -invading phagocytes is slowly emerging. In this perspective, we propose that in CNS neuroinflammatory diseases, tissue-resident macrophages (TRMs) contribute to the clearing of debris and resolution of inflammation, whereas blood-borne phagocytes are drivers of immunopathology. We discuss the remaining challenges to resolve which specialized mononuclear phagocyte populations are driving or suppressing immune effector function, thereby potentially dictating the outcome of autoimmunity or brain cancer.
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Affiliation(s)
- Sarah Mundt
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Melanie Greter
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Burkhard Becher
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland.
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18
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Miyata S. Glial functions in the blood-brain communication at the circumventricular organs. Front Neurosci 2022; 16:991779. [PMID: 36278020 PMCID: PMC9583022 DOI: 10.3389/fnins.2022.991779] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
The circumventricular organs (CVOs) are located around the brain ventricles, lack a blood-brain barrier (BBB) and sense blood-derived molecules. This review discusses recent advances in the importance of CVO functions, especially glial cells transferring periphery inflammation signals to the brain. The CVOs show size-limited vascular permeability, allowing the passage of molecules with molecular weight <10,000. This indicates that the lack of an endothelial cell barrier does not mean the free movement of blood-derived molecules into the CVO parenchyma. Astrocytes and tanycytes constitute a dense barrier at the distal CVO subdivision, preventing the free diffusion of blood-derived molecules into neighboring brain regions. Tanycytes in the CVOs mediate communication between cerebrospinal fluid and brain parenchyma via transcytosis. Microglia and macrophages of the CVOs are essential for transmitting peripheral information to other brain regions via toll-like receptor 2 (TLR2). Inhibition of TLR2 signaling or depletion of microglia and macrophages in the brain eliminates TLR2-dependent inflammatory responses. In contrast to TLR2, astrocytes and tanycytes in the CVOs of the brain are crucial for initiating lipopolysaccharide (LPS)-induced inflammatory responses via TLR4. Depletion of microglia and macrophages augments LPS-induced fever and chronic sickness responses. Microglia and macrophages in the CVOs are continuously activated, even under normal physiological conditions, as they exhibit activated morphology and express the M1/M2 marker proteins. Moreover, the microglial proliferation occurs in various regions, such as the hypothalamus, medulla oblongata, and telencephalon, with a marked increase in the CVOs, due to low-dose LPS administration, and after high-dose LPS administration, proliferation is seen in most brain regions, except for the cerebral cortex and hippocampus. A transient increase in the microglial population is beneficial during LPS-induced inflammation for attenuating sickness response. Transient receptor potential receptor vanilloid 1 expressed in astrocytes and tanycytes of the CVOs is responsible for thermoregulation upon exposure to a warm environment less than 37°C. Alternatively, Nax expressed in astrocytes and tanycytes of the CVOs is crucial for maintaining body fluid homeostasis. Thus, recent findings indicate that glial cells in the brain CVOs are essential for initiating neuroinflammatory responses and maintaining body fluid and thermal homeostasis.
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19
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Zheng L, Guo Y, Zhai X, Zhang Y, Chen W, Zhu Z, Xuan W, Li P. Perivascular macrophages in the CNS: From health to neurovascular diseases. CNS Neurosci Ther 2022; 28:1908-1920. [PMID: 36128654 PMCID: PMC9627394 DOI: 10.1111/cns.13954] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/15/2022] [Accepted: 07/22/2022] [Indexed: 02/06/2023] Open
Abstract
Brain perivascular macrophages (PVMs) are attracting increasing attention as this emerging cell population in the brain has multifaced roles in supporting the central nervous system structure, brain development, and maintaining physiological functions. They also widely participate in neurological diseases such as neurodegeneration and ischemic stroke. Moreover, PVMs have been reported to have both beneficial and detrimental effects under different pathological contexts. Advanced research technologies allowed the further in-depth study of PVMs and revealed novel concepts in their origins, differentiation, and regulatory mechanisms. Deepened understanding of the roles of PVMs in different brain pathological conditions can reveal novel phenotypic changes and regulatory signaling, which might pave the way for the development of novel treatment strategies targeting PVMs.
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Affiliation(s)
- Li Zheng
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Yunlu Guo
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Xiaozhu Zhai
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Yueman Zhang
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Weijie Chen
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Ziyu Zhu
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Wei Xuan
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
| | - Peiying Li
- Department of Anesthesiology, State Key Laboratory of Oncogenes and Related GenesShanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
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20
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Matsuoka RL, Buck LD, Vajrala KP, Quick RE, Card OA. Historical and current perspectives on blood endothelial cell heterogeneity in the brain. Cell Mol Life Sci 2022; 79:372. [PMID: 35726097 PMCID: PMC9209386 DOI: 10.1007/s00018-022-04403-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/18/2022] [Accepted: 05/25/2022] [Indexed: 11/28/2022]
Abstract
Dynamic brain activity requires timely communications between the brain parenchyma and circulating blood. Brain-blood communication is facilitated by intricate networks of brain vasculature, which display striking heterogeneity in structure and function. This vascular cell heterogeneity in the brain is fundamental to mediating diverse brain functions and has long been recognized. However, the molecular basis of this biological phenomenon has only recently begun to be elucidated. Over the past century, various animal species and in vitro systems have contributed to the accumulation of our fundamental and phylogenetic knowledge about brain vasculature, collectively advancing this research field. Historically, dye tracer and microscopic observations have provided valuable insights into the anatomical and functional properties of vasculature across the brain, and these techniques remain an important approach. Additionally, recent advances in molecular genetics and omics technologies have revealed significant molecular heterogeneity within brain endothelial and perivascular cell types. The combination of these conventional and modern approaches has enabled us to identify phenotypic differences between healthy and abnormal conditions at the single-cell level. Accordingly, our understanding of brain vascular cell states during physiological, pathological, and aging processes has rapidly expanded. In this review, we summarize major historical advances and current knowledge on blood endothelial cell heterogeneity in the brain, and discuss important unsolved questions in the field.
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Affiliation(s)
- Ryota L Matsuoka
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA. .,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA.
| | - Luke D Buck
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Keerti P Vajrala
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA.,Kansas City University College of Osteopathic Medicine, Kansas City, MO 64106, USA
| | - Rachael E Quick
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Olivia A Card
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA
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21
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Mendes NF, Velloso LA. Perivascular macrophages in high-fat diet-induced hypothalamic inflammation. J Neuroinflammation 2022; 19:136. [PMID: 35681242 PMCID: PMC9185933 DOI: 10.1186/s12974-022-02519-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/01/2022] [Indexed: 02/06/2023] Open
Abstract
Brain macrophages and microglia are centrally involved in immune surveillance of the central nervous system. Upon inflammatory stimuli, they become reactive and release key molecules to prevent further damage to the neuronal network. In the hypothalamic area, perivascular macrophages (PVMs) are the first line of host defence against pathogenic organisms, particles and/or substances from the blood. They are distributed throughout the circumventricular organ median eminence, wrapping endothelial cells from fenestrated portal capillaries and in the hypothalamic vascular network, where they are localised in the perivascular space of the blood-brain barrier (BBB). Some studies have indicated that PVMs from the hypothalamus increase the expression of inducible nitric oxide synthase and vascular endothelial growth factor upon feeding for a long time on a high-fat diet. This adaptive response contributes to the impairment of glucose uptake, facilitates BBB leakage and leads to increased lipid and inflammatory cell influx towards the hypothalamic parenchyma. Despite these early findings, there is still a lack of studies exploring the mechanisms by which PVMs contribute to the development of obesity-related hypothalamic dysfunction, particularly at the early stages when there is chemotaxis of peripheral myeloid cells into the mediobasal hypothalamus. Here, we reviewed the studies involving the ontogeny, hallmarks and main features of brain PVMs in vascular homeostasis, inflammation and neuroendocrine control. This review provides a framework for understanding the potential involvement of PVMs in diet-induced hypothalamic inflammation.
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Affiliation(s)
- Natalia F Mendes
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Rua Carl Von Linnaeus s/n, Instituto de Biologia - Bloco Z. Campus Universitário Zeferino Vaz - Barão Geraldo, Campinas, SP, 13083-864, Brazil.
| | - Licio A Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Rua Carl Von Linnaeus s/n, Instituto de Biologia - Bloco Z. Campus Universitário Zeferino Vaz - Barão Geraldo, Campinas, SP, 13083-864, Brazil.,National Institute of Science and Technology on Neuroimmunomodulation, Rio de Janeiro, Brazil
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22
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Mildenberger W, Stifter SA, Greter M. Diversity and function of brain-associated macrophages. Curr Opin Immunol 2022; 76:102181. [DOI: 10.1016/j.coi.2022.102181] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/18/2022] [Accepted: 03/19/2022] [Indexed: 02/07/2023]
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23
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Glial Modulation of Energy Balance: The Dorsal Vagal Complex Is No Exception. Int J Mol Sci 2022; 23:ijms23020960. [PMID: 35055143 PMCID: PMC8779587 DOI: 10.3390/ijms23020960] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/11/2022] [Accepted: 01/13/2022] [Indexed: 02/04/2023] Open
Abstract
The avoidance of being overweight or obese is a daily challenge for a growing number of people. The growing proportion of people suffering from a nutritional imbalance in many parts of the world exemplifies this challenge and emphasizes the need for a better understanding of the mechanisms that regulate nutritional balance. Until recently, research on the central regulation of food intake primarily focused on neuronal signaling, with little attention paid to the role of glial cells. Over the last few decades, our understanding of glial cells has changed dramatically. These cells are increasingly regarded as important neuronal partners, contributing not just to cerebral homeostasis, but also to cerebral signaling. Our understanding of the central regulation of energy balance is part of this (r)evolution. Evidence is accumulating that glial cells play a dynamic role in the modulation of energy balance. In the present review, we summarize recent data indicating that the multifaceted glial compartment of the brainstem dorsal vagal complex (DVC) should be considered in research aimed at identifying feeding-related processes operating at this level.
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Heidarzadeh M, Gürsoy-Özdemir Y, Kaya M, Eslami Abriz A, Zarebkohan A, Rahbarghazi R, Sokullu E. Exosomal delivery of therapeutic modulators through the blood-brain barrier; promise and pitfalls. Cell Biosci 2021; 11:142. [PMID: 34294165 PMCID: PMC8296716 DOI: 10.1186/s13578-021-00650-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/05/2021] [Indexed: 12/16/2022] Open
Abstract
Nowadays, a large population around the world, especially the elderly, suffers from neurological inflammatory and degenerative disorders/diseases. Current drug delivery strategies are facing different challenges because of the presence of the BBB, which limits the transport of various substances and cells to brain parenchyma. Additionally, the low rate of successful cell transplantation to the brain injury sites leads to efforts to find alternative therapies. Stem cell byproducts such as exosomes are touted as natural nano-drug carriers with 50-100 nm in diameter. These nano-sized particles could harbor and transfer a plethora of therapeutic agents and biological cargos to the brain. These nanoparticles would offer a solution to maintain paracrine cell-to-cell communications under healthy and inflammatory conditions. The main question is that the existence of the intact BBB could limit exosomal trafficking. Does BBB possess some molecular mechanisms that facilitate the exosomal delivery compared to the circulating cell? Although preliminary studies have shown that exosomes could cross the BBB, the exact molecular mechanism(s) beyond this phenomenon remains unclear. In this review, we tried to compile some facts about exosome delivery through the BBB and propose some mechanisms that regulate exosomal cross in pathological and physiological conditions.
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Affiliation(s)
- Morteza Heidarzadeh
- Koç University Research Center for Translational Medicine (KUTTAM), Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey
| | - Yasemin Gürsoy-Özdemir
- Koç University Research Center for Translational Medicine (KUTTAM), Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey.,Neurology Department, Koç University School of Medicine, Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey
| | - Mehmet Kaya
- Koç University Research Center for Translational Medicine (KUTTAM), Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey.,Physiology Department, Koç University School of Medicine, Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey
| | - Aysan Eslami Abriz
- Department of Medical Nanotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Amir Zarebkohan
- Department of Medical Nanotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Reza Rahbarghazi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. .,Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Emel Sokullu
- Koç University Research Center for Translational Medicine (KUTTAM), Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey. .,Biophysics Department, Koç University School of Medicine, Rumeli Feneri, 34450, Sariyer, Istanbul, Turkey.
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25
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Oliveira-Giacomelli Á, Petiz LL, Andrejew R, Turrini N, Silva JB, Sack U, Ulrich H. Role of P2X7 Receptors in Immune Responses During Neurodegeneration. Front Cell Neurosci 2021; 15:662935. [PMID: 34122013 PMCID: PMC8187565 DOI: 10.3389/fncel.2021.662935] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/26/2021] [Indexed: 01/16/2023] Open
Abstract
P2X7 receptors are ion-gated channels activated by ATP. Under pathological conditions, the extensive release of ATP induces sustained P2X7 receptor activation, culminating in induction of proinflammatory pathways with inflammasome assembly and cytokine release. These inflammatory conditions, whether occurring peripherally or in the central nervous system (CNS), increase blood-brain-barrier (BBB) permeability. Besides its well-known involvement in neurodegeneration and neuroinflammation, the P2X7 receptor may induce BBB disruption and chemotaxis of peripheral immune cells to the CNS, resulting in brain parenchyma infiltration. For instance, despite common effects on cytokine release, P2X7 receptor signaling is also associated with metalloproteinase secretion and activation, as well as migration and differentiation of T lymphocytes, monocytes and dendritic cells. Here we highlight that peripheral immune cells mediate the pathogenesis of Multiple Sclerosis and Parkinson's and Alzheimer's disease, mainly through T lymphocyte, neutrophil and monocyte infiltration. We propose that P2X7 receptor activation contributes to neurodegenerative disease progression beyond its known effects on the CNS. This review discusses how P2X7 receptor activation mediates responses of peripheral immune cells within the inflamed CNS, as occurring in the aforementioned diseases.
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Affiliation(s)
| | - Lyvia Lintzmaier Petiz
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Roberta Andrejew
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Natalia Turrini
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Jean Bezerra Silva
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Ulrich Sack
- Institute of Clinical Immunology, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
- Institute of Clinical Immunology, Medical Faculty, University of Leipzig, Leipzig, Germany
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26
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Ivan DC, Walthert S, Berve K, Steudler J, Locatelli G. Dwellers and Trespassers: Mononuclear Phagocytes at the Borders of the Central Nervous System. Front Immunol 2021; 11:609921. [PMID: 33746939 PMCID: PMC7973121 DOI: 10.3389/fimmu.2020.609921] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 12/29/2020] [Indexed: 01/02/2023] Open
Abstract
The central nervous system (CNS) parenchyma is enclosed and protected by a multilayered system of cellular and acellular barriers, functionally separating glia and neurons from peripheral circulation and blood-borne immune cells. Populating these borders as dynamic observers, CNS-resident macrophages contribute to organ homeostasis. Upon autoimmune, traumatic or neurodegenerative inflammation, these phagocytes start playing additional roles as immune regulators contributing to disease evolution. At the same time, pathological CNS conditions drive the migration and recruitment of blood-borne monocyte-derived cells across distinct local gateways. This invasion process drastically increases border complexity and can lead to parenchymal infiltration of blood-borne phagocytes playing a direct role both in damage and in tissue repair. While recent studies and technical advancements have highlighted the extreme heterogeneity of these resident and CNS-invading cells, both the compartment-specific mechanism of invasion and the functional specification of intruding and resident cells remain unclear. This review illustrates the complexity of mononuclear phagocytes at CNS interfaces, indicating how further studies of CNS border dynamics are crucially needed to shed light on local and systemic regulation of CNS functions and dysfunctions.
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27
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A Binary Cre Transgenic Approach Dissects Microglia and CNS Border-Associated Macrophages. Immunity 2020; 54:176-190.e7. [PMID: 33333014 DOI: 10.1016/j.immuni.2020.11.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/09/2020] [Accepted: 11/16/2020] [Indexed: 02/06/2023]
Abstract
The developmental and molecular heterogeneity of tissue macrophages is unravelling, as are their diverse contributions to physiology and pathophysiology. Moreover, also given tissues harbor macrophages in discrete anatomic locations. Functional contributions of specific cell populations can in mice be dissected using Cre recombinase-mediated mutagenesis. However, single promoter-based Cre models show limited specificity for cell types. Focusing on macrophages in the brain, we establish here a binary transgenic system involving complementation-competent NCre and CCre fragments whose expression is driven by distinct promoters: Sall1ncre: Cx3cr1ccre mice specifically target parenchymal microglia and compound transgenic Lyve1ncre: Cx3cr1ccre animals target vasculature-associated macrophages, in the brain, as well as other tissues. We imaged the respective cell populations and retrieved their specific translatomes using the RiboTag in order to define them and analyze their differential responses to a challenge. Collectively, we establish the value of binary transgenesis to dissect tissue macrophage compartments and their functions.
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28
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Ross JM, Kim C, Allen D, Crouch EE, Narsinh K, Cooke DL, Abla AA, Nowakowski TJ, Winkler EA. The Expanding Cell Diversity of the Brain Vasculature. Front Physiol 2020; 11:600767. [PMID: 33343397 PMCID: PMC7744630 DOI: 10.3389/fphys.2020.600767] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/10/2020] [Indexed: 12/12/2022] Open
Abstract
The cerebrovasculature is essential to brain health and is tasked with ensuring adequate delivery of oxygen and metabolic precursors to ensure normal neurologic function. This is coordinated through a dynamic, multi-directional cellular interplay between vascular, neuronal, and glial cells. Molecular exchanges across the blood-brain barrier or the close matching of regional blood flow with brain activation are not uniformly assigned to arteries, capillaries, and veins. Evidence has supported functional segmentation of the brain vasculature. This is achieved in part through morphologic or transcriptional heterogeneity of brain vascular cells-including endothelium, pericytes, and vascular smooth muscle. Advances with single cell genomic technologies have shown increasing cell complexity of the brain vasculature identifying previously unknown cell types and further subclassifying transcriptional diversity in cardinal vascular cell types. Cell-type specific molecular transitions or zonations have been identified. In this review, we summarize emerging evidence for the expanding vascular cell diversity in the brain and how this may provide a cellular basis for functional segmentation along the arterial-venous axis.
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Affiliation(s)
- Jayden M. Ross
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, United States
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, United States
- The Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States
| | - Chang Kim
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, United States
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, United States
- The Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States
| | - Denise Allen
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, United States
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, United States
- The Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States
| | - Elizabeth E. Crouch
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, United States
| | - Kazim Narsinh
- Department of Radiology, University of California, San Francisco, San Francisco, CA, United States
| | - Daniel L. Cooke
- Department of Radiology, University of California, San Francisco, San Francisco, CA, United States
| | - Adib A. Abla
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Tomasz J. Nowakowski
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, United States
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, United States
- The Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States
- Department of Radiology, University of California, San Francisco, San Francisco, CA, United States
| | - Ethan A. Winkler
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
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Verheggen ICM, de Jong JJA, van Boxtel MPJ, Postma AA, Verhey FRJ, Jansen JFA, Backes WH. Permeability of the windows of the brain: feasibility of dynamic contrast-enhanced MRI of the circumventricular organs. Fluids Barriers CNS 2020; 17:66. [PMID: 33115484 PMCID: PMC7594295 DOI: 10.1186/s12987-020-00228-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 10/17/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Circumventricular organs (CVOs) are small structures without a blood-brain barrier surrounding the brain ventricles that serve homeostasic functions and facilitate communication between the blood, cerebrospinal fluid and brain. Secretory CVOs release peptides and sensory CVOs regulate signal transmission. However, pathogens may enter the brain through the CVOs and trigger neuroinflammation and neurodegeneration. We investigated the feasibility of dynamic contrast-enhanced (DCE) MRI to assess the CVO permeability characteristics in vivo, and expected significant contrast uptake in these regions, due to blood-brain barrier absence. METHODS Twenty healthy, middle-aged to older males underwent brain DCE MRI. Pharmacokinetic modeling was applied to contrast concentration time-courses of CVOs, and in reference to white and gray matter. We investigated whether a significant and positive transfer from blood to brain could be measured in the CVOs, and whether this differed between secretory and sensory CVOs or from normal-appearing brain matter. RESULTS In both the secretory and sensory CVOs, the transfer constants were significantly positive, and all secretory CVOs had significantly higher transfer than each sensory CVO. The transfer constants in both the secretory and sensory CVOs were higher than in the white and gray matter. CONCLUSIONS Current measurements confirm the often-held assumption of highly permeable CVOs, of which the secretory types have the strongest blood-to-brain transfer. The current study suggests that DCE MRI could be a promising technique to further assess the function of the CVOs and how pathogens can potentially enter the brain via these structures. TRIAL REGISTRATION Netherlands Trial Register number: NL6358, date of registration: 2017-03-24.
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Affiliation(s)
- Inge C M Verheggen
- Department of Psychiatry and Neuropsychology, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands.
- Alzheimer Center Limburg, Maastricht, The Netherlands.
| | - Joost J A de Jong
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Martin P J van Boxtel
- Department of Psychiatry and Neuropsychology, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands
- Alzheimer Center Limburg, Maastricht, The Netherlands
| | - Alida A Postma
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Frans R J Verhey
- Department of Psychiatry and Neuropsychology, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands
- Alzheimer Center Limburg, Maastricht, The Netherlands
| | - Jacobus F A Jansen
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Walter H Backes
- School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
- School for Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
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30
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Depletion of microglia and macrophages with clodronate liposomes attenuates zymosan-induced Fos expression and hypothermia in the adult mouse. J Neuroimmunol 2020; 344:577244. [DOI: 10.1016/j.jneuroim.2020.577244] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/04/2020] [Accepted: 04/14/2020] [Indexed: 12/14/2022]
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31
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Yang T, Guo R, Zhang F. Brain perivascular macrophages: Recent advances and implications in health and diseases. CNS Neurosci Ther 2019; 25:1318-1328. [PMID: 31749316 PMCID: PMC7154594 DOI: 10.1111/cns.13263] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 12/20/2022] Open
Abstract
Brain perivascular macrophages (PVMs) belong to a distinct population of brain‐resident myeloid cells located within the perivascular space surrounding arterioles and venules. Their characterization depends on the combination of anatomical localization, phagocytic capacity, and molecular markers. Under physiological status, they provide structural and functional support for maintaining brain homeostasis, including facilitation of blood‐brain barrier integrity and lymphatic drainage, and exertion of immune functions such as phagocytosis and antigen presentation. Increasing evidence also implicates their specific roles in diseased brain, ranging from cerebrovascular diseases, Aβ pathologies, infections, and autoimmunity. Collectively, PVMs are key components of the brain‐resident immune system, actively participate in a broad‐spectrum of processes in normal and diseased status. Details of the processes are largely underexplored. Targeting PVMs would lead to new insights and be a promising strategy for a broad array of human diseases.
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Affiliation(s)
- Tuo Yang
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ruiming Guo
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Feng Zhang
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh, Pittsburgh, Pennsylvania
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Sou K, Le DL, Sato H. Nanocapsules for Programmed Neurotransmitter Release: Toward Artificial Extracellular Synaptic Vesicles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900132. [PMID: 30887709 DOI: 10.1002/smll.201900132] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/20/2019] [Indexed: 06/09/2023]
Abstract
Nanocapsules present a promising platform for delivering chemicals and biomolecules to a site of action in a living organism. Because the biological action of the encapsulated molecules is blocked until they are released from the nanocapsules, the encapsulation structure enables triggering of the topical and timely action of the molecules at the target site. A similar mechanism seems promising for the spatiotemporal control of signal transduction triggered by the release of signal molecules in neuronal, metabolic, and immune systems. From this perspective, nanocapsules can be regarded as practical tools to apply signal molecules such as neurotransmitters to intervene in signal transduction. However, spatiotemporal control of the payload release from nanocapsules persists as a key technical issue. Stimulus-responsive nanocapsules that release payloads in response to external input of physical stimuli are promising platforms to enable programmed payload release. These programmable nanocapsules encapsulating neurotransmitters are expected to lead to new insights and perspectives related to artificial extracellular synaptic vesicles that might provide an experimental and therapeutic strategy for neuromodulation and nervous system disorders.
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Affiliation(s)
- Keitaro Sou
- Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo, 169-8555, Japan
| | - Duc Long Le
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Hirotaka Sato
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
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Plenge-Tellechea LF, Hernández-Ramos ÁD, Muñoz JM, Barraza-Garza G, Rico-Escobar E, Meléndez-Martínez D. Acanthocytosis and brain damage in area postrema and choroid plexus: Description of novel signs of Loxosceles apachea envenomation in rats. PLoS One 2019; 14:e0211689. [PMID: 30730934 PMCID: PMC6366775 DOI: 10.1371/journal.pone.0211689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 01/18/2019] [Indexed: 01/30/2023] Open
Abstract
Loxocelism is a neglected medical problem that depends on its severity, can cause a cutaneous or viscero-cutaneous syndrome. This syndrome is characterized by hemostatic effects and necrosis, and the severity of the loxoscelism depends on the amount of venom injected, the zone of inoculation, and the species. In the Chihuahuan desert, the most abundant species is L. apachea. Its venom and biological effects are understudied, including neurological effects. Thus, our aim is to explore the effect of this regional species of medical interest in the United States-Mexico border community, using rat blood and central nervous system (CNS), particularly, two brain structures involved in brain homeostasis, Area postrema (AP) and Choroid plexus (PC). L. apachea specimens were collected and venom was obtained. Different venom concentrations (0, 0.178 and 0.87 μg/g) were inoculated into Sprague-Dawley rats (intraperitoneal injection). Subsequently, blood was extracted and stained with Wright staining; coronal sections of AP were obtained and stained with Hematoxylin-Eosin (HE) staining and laminin γ immunolabelling, the same was done with CP sections. Blood, AP and CP were observed under the microscope and abnormalities in erythrocytes and fluctuation in leukocyte types were described and quantified in blood. Capillaries were also quantified in AP and damage was described in CP. L. apachea venom produced a segmented neutrophil increment (neutrophilia), lymphocyte diminishment (leukopenia) and erythrocytes presented membrane abnormalities (acanthocytosis). Extravasated erythrocytes were observed in HE stained sections from both, AP and CP, which suggest that near to this section a hemorrhage is present; through immunohistofluorescence, a diminishment of laminin γ was observed in AP endothelial cells and in CP ependymal cells when these structures were exposed to L. apachea venom. In conclusion, L. apachea venom produced leukopenia, netrophilia and acanthocytosis in rat peripheral blood, and also generated hemorrhages on AP and CP through degradation of laminin γ.
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Affiliation(s)
- Luis Fernando Plenge-Tellechea
- Laboratorio de Biología Molecular y Bioquímica, Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México
- * E-mail:
| | - Ángel Daniel Hernández-Ramos
- Laboratorio de Biología Molecular y Bioquímica, Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México
| | - Juan Manuel Muñoz
- Laboratorio de Biología Molecular y Bioquímica, Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México
| | - Guillermo Barraza-Garza
- Laboratorio de Biología Molecular y Bioquímica, Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México
| | - Edna Rico-Escobar
- Laboratorio de Biología Molecular y Bioquímica, Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México
| | - David Meléndez-Martínez
- Laboratorio de Biología Molecular y Bioquímica, Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México
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Bentivoglio M, Kristensson K, Rottenberg ME. Circumventricular Organs and Parasite Neurotropism: Neglected Gates to the Brain? Front Immunol 2018; 9:2877. [PMID: 30619260 PMCID: PMC6302769 DOI: 10.3389/fimmu.2018.02877] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 11/22/2018] [Indexed: 12/20/2022] Open
Abstract
Circumventricular organs (CVOs), neural structures located around the third and fourth ventricles, harbor, similarly to the choroid plexus, vessels devoid of a blood-brain barrier (BBB). This enables them to sense immune-stimulatory molecules in the blood circulation, but may also increase chances of exposure to microbes. In spite of this, attacks to CVOs by microbes are rarely described. It is here highlighted that CVOs and choroid plexus can be infected by pathogens circulating in the bloodstream, providing a route for brain penetration, as shown by infections with the parasites Trypanosoma brucei. Immune responses elicited by pathogens or systemic infections in the choroid plexus and CVOs are briefly outlined. From the choroid plexus trypanosomes can seed into the ventricles and initiate accelerated infiltration of T cells and parasites in periventricular areas. The highly motile trypanosomes may also enter the brain parenchyma from the median eminence, a CVO located at the base of the third ventricle, by crossing the border into the BBB-protected hypothalamic arcuate nuclei. A gate may, thus, be provided for trypanosomes to move into brain areas connected to networks of regulation of circadian rhythms and sleep-wakefulness, to which other CVOs are also connected. Functional imbalances in these networks characterize human African trypanosomiasis, also called sleeping sickness. They are distinct from the sickness response to bacterial infections, but can occur in common neuropsychiatric diseases. Altogether the findings lead to the question: does the neglect in reporting microbe attacks to CVOs reflect lack of awareness in investigations or of gate-opening capability by microbes?
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Affiliation(s)
- Marina Bentivoglio
- Department of Neuroscience Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | | | - Martin E. Rottenberg
- Department Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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35
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Alpár A, Benevento M, Romanov RA, Hökfelt T, Harkany T. Hypothalamic cell diversity: non-neuronal codes for long-distance volume transmission by neuropeptides. Curr Opin Neurobiol 2018; 56:16-23. [PMID: 30471413 DOI: 10.1016/j.conb.2018.10.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 10/24/2018] [Indexed: 11/24/2022]
Abstract
Volume transmission is a mode of intercellular communication using cerebral liquor to deliver signal molecules over long distances and allow their action for extended periods. For hypothalamic neuropeptides, nerve endings amongst ependymal cells are seen as a site of release into the cerebrospinal fluid. Recent single-cell RNA-seq data identify tanycytes and ventricular ependyma as alternative sources by being unexpectedly rich in neuroactive substances. This notion, coupled with circuit analysis showing regionalized innervation of periventricular ependyma by intrahypothalamic neurons, could allow for the integration of hypothalamic neuronal activity patterns with brain-wide activity changes upon metabolic challenges through phasic volume transmission primed by neuron-ependyma coupling. Here, we discuss emerging data for an ependymal interface and its breaches in neuropsychiatric disease.
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Affiliation(s)
- Alán Alpár
- SE NAP Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, H-1085 Budapest, Hungary; Department of Anatomy, Histology, and Embryology, Semmelweis University, H-1085 Budapest, Hungary
| | - Marco Benevento
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria
| | - Roman A Romanov
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria
| | - Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, SE-17165 Solna, Sweden
| | - Tibor Harkany
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria; Department of Neuroscience, Karolinska Institutet, SE-17165 Solna, Sweden.
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Takagi S, Furube E, Nakano Y, Morita M, Miyata S. Microglia are continuously activated in the circumventricular organs of mouse brain. J Neuroimmunol 2017; 331:74-86. [PMID: 29107327 DOI: 10.1016/j.jneuroim.2017.10.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 10/13/2017] [Accepted: 10/13/2017] [Indexed: 12/11/2022]
Abstract
Microglia are the primary resident immune cells of the brain parenchyma and transform into the amoeboid form in the "activated state" under pathological conditions from the ramified form in the "resting state" under physiologically healthy conditions. In the present study, we found that microglia in the circumventricular organs (CVOs) of adult mice displayed the amoeboid form with fewer branched cellular processes even under normal conditions; however, those in other brain regions showed the ramified form, which is characterized by well-branched and dendritic cellular processes. Moreover, microglia in the CVOs showed the strong protein expression of the M1 markers CD16/32 and CD86 and M2 markers CD206 and Ym1 without any pathological stimulation. Thus, the present results indicate that microglia in the CVOs of adult mice are morphologically and functionally activated under normal conditions, possibly due to the specialized features of the CVOs, namely, the entry of blood-derived molecules into parenchyma through fenestrated capillaries and the presence of neural stem cells.
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Affiliation(s)
- Shohei Takagi
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Eriko Furube
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yousuke Nakano
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; Department of Anatomy and Brain Science, Kansai Medical University, Hirakata, Japan
| | - Mitsuhiro Morita
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Seiji Miyata
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
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Konishi H, Kobayashi M, Kunisawa T, Imai K, Sayo A, Malissen B, Crocker PR, Sato K, Kiyama H. Siglec-H is a microglia-specific marker that discriminates microglia from CNS-associated macrophages and CNS-infiltrating monocytes. Glia 2017; 65:1927-1943. [PMID: 28836308 DOI: 10.1002/glia.23204] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/25/2017] [Accepted: 07/25/2017] [Indexed: 01/06/2023]
Abstract
Several types of myeloid cell are resident in the CNS. In the steady state, microglia are present in the CNS parenchyma, whereas macrophages reside in boundary regions of the CNS, such as perivascular spaces, the meninges and choroid plexus. In addition, monocytes infiltrate into the CNS parenchyma from circulation upon blood-brain barrier breakdown after CNS injury and inflammation. Although several markers, such as CD11b and ionized calcium-binding adapter molecule 1 (Iba1), are frequently used as microglial markers, they are also expressed by other types of myeloid cell and microglia-specific markers were not defined until recently. Previous transcriptome analyses of isolated microglia identified a transmembrane lectin, sialic acid-binding immunoglobulin-like lectin H (Siglec-H), as a molecular signature for microglia; however, this was not confirmed by histological studies in the nervous system and the reliability of Siglec-H as a microglial marker remained unclear. Here, we demonstrate that Siglec-H is an authentic marker for microglia in mice by immunohistochemistry using a Siglec-H-specific antibody. Siglec-H was expressed by parenchymal microglia from developmental stages to adulthood, and the expression was maintained in activated microglia under injury or inflammatory condition. However, Siglec-H expression was absent from CNS-associated macrophages and CNS-infiltrating monocytes, except for a minor subset of cells. We also show that the Siglech gene locus is a feasible site for specific targeting of microglia in the nervous system. In conclusion, Siglec-H is a reliable marker for microglia that will allow histological identification of microglia and microglia-specific gene manipulation in the nervous system.
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Affiliation(s)
- Hiroyuki Konishi
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Masaaki Kobayashi
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Taikan Kunisawa
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Kenta Imai
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Akira Sayo
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.,Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Bernard Malissen
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS UMR, Marseille, 13288, France
| | - Paul R Crocker
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom
| | - Katsuaki Sato
- Division of Immunology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, 889-1692, Japan
| | - Hiroshi Kiyama
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
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Faraco G, Park L, Anrather J, Iadecola C. Brain perivascular macrophages: characterization and functional roles in health and disease. J Mol Med (Berl) 2017; 95:1143-1152. [PMID: 28782084 DOI: 10.1007/s00109-017-1573-x] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/21/2017] [Accepted: 07/28/2017] [Indexed: 12/12/2022]
Abstract
Perivascular macrophages (PVM) are a distinct population of resident brain macrophages characterized by a close association with the cerebral vasculature. PVM migrate from the yolk sac into the brain early in development and, like microglia, are likely to be a self-renewing cell population that, in the normal state, is not replenished by circulating monocytes. Increasing evidence implicates PVM in several disease processes, ranging from brain infections and immune activation to regulation of the hypothalamic-adrenal axis and neurovascular-neurocognitive dysfunction in the setting of hypertension, Alzheimer disease pathology, or obesity. These effects involve crosstalk between PVM and cerebral endothelial cells, interaction with circulating immune cells, and/or production of reactive oxygen species. Overall, the available evidence supports the idea that PVM are a key component of the brain-resident immune system with broad implications for the pathogenesis of major brain diseases. A better understanding of the biology and pathobiology of PVM may lead to new insights and therapeutic strategies for a wide variety of brain diseases.
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Affiliation(s)
- Giuseppe Faraco
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 E61st Street, New York, NY, USA.
| | - Laibaik Park
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 E61st Street, New York, NY, USA
| | - Josef Anrather
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 E61st Street, New York, NY, USA
| | - Costantino Iadecola
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 E61st Street, New York, NY, USA.
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Oliveira M, Fernández F, Solé J, Pumarola M. Morphological, histological and immunohistochemical study of the area postrema in the dog. Anat Sci Int 2017; 93:188-196. [PMID: 28063139 DOI: 10.1007/s12565-016-0388-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 12/10/2016] [Indexed: 02/05/2023]
Abstract
Circumventricular organs are specialized brain structures that are located mainly at the midsagittal line, around the third and fourth ventricles, often protruding into the lumen. They are positioned at the interface between the neuroparenchyma and the ventricular system of the brain. These highly vascularized nervous tissue structures differ from the brain parenchyma, as they lack a blood-brain barrier. Circumventricular organs have specialized sensory and secretory functions. It is essential for any pathologist who evaluates brain sections to have a solid knowledge of microscopic neuroanatomy and to recognize these numerous specialized structures within the nervous system as normal and not mistake them for pathological changes. The purpose of this study was to provide, for the first time, a detailed and complete histological description of the healthy canine area postrema and to determine its resemblance to that of other mammalian species. Anatomical dissections with routine histological and immunohistochemical techniques were carried out on ten canine brains. The cellular composition of area postrema proved to be largely comparable to that of other mammal species.
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Affiliation(s)
- Maria Oliveira
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. .,Fundació Hospital Clínic Veterinari, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. .,Pride Veterinary Centre, Derby, DE24 8HX, UK.
| | - Francisco Fernández
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Jordi Solé
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Martí Pumarola
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
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Miyata S. New aspects in fenestrated capillary and tissue dynamics in the sensory circumventricular organs of adult brains. Front Neurosci 2015; 9:390. [PMID: 26578857 PMCID: PMC4621430 DOI: 10.3389/fnins.2015.00390] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022] Open
Abstract
The blood-brain barrier (BBB) generally consists of endothelial tight junction barriers that prevent the free entry of blood-derived substances, thereby maintaining the extracellular environment of the brain. However, the circumventricular organs (CVOs), which are located along the midlines of the brain ventricles, lack these endothelial barriers and have fenestrated capillaries; therefore, they have a number of essential functions, including the transduction of information between the blood circulation and brain. Previous studies have demonstrated the extensive contribution of the CVOs to body fluid and thermal homeostasis, energy balance, the chemoreception of blood-derived substances, and neuroinflammation. In this review, recent advances have been discussed in fenestrated capillary characterization and dynamic tissue reconstruction accompanied by angiogenesis and neurogliogenesis in the sensory CVOs of adult brains. The sensory CVOs, including the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), and area postrema (AP), have size-selective and heterogeneous vascular permeabilities. Astrocyte-/tanycyte-like neural stem cells (NSCs) sense blood- and cerebrospinal fluid-derived information through the transient receptor potential vanilloid 1, a mechanical/osmotic receptor, Toll-like receptor 4, a lipopolysaccharide receptor, and Nax, a Na-sensing Na channel. They also express tight junction proteins and densely and tightly surround mature neurons to protect them from blood-derived neurotoxic substances, indicating that the NSCs of the CVOs perform BBB functions while maintaining the capacity to differentiate into new neurons and glial cells. In addition to neurogliogenesis, the density of fenestrated capillaries is regulated by angiogenesis, which is accompanied by the active proliferation and sprouting of endothelial cells. Vascular endothelial growth factor (VEGF) signaling may be involved in angiogenesis and neurogliogenesis, both of which affect vascular permeability. Thus, recent findings advocate novel concepts for the CVOs, which have the dynamic features of vascular and parenchymal tissues.
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Affiliation(s)
- Seiji Miyata
- Department of Applied Biology, Kyoto Institute of TechnologyKyoto, Japan
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41
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The Food Contaminant Mycotoxin Deoxynivalenol Inhibits the Swallowing Reflex in Anaesthetized Rats. PLoS One 2015; 10:e0133355. [PMID: 26192767 PMCID: PMC4507856 DOI: 10.1371/journal.pone.0133355] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 06/26/2015] [Indexed: 12/04/2022] Open
Abstract
Deoxynivalenol (DON), one of the most abundant mycotoxins found on cereals, is known to be implicated in acute and chronic illnesses in both humans and animals. Among the symptoms, anorexia, reduction of weight gain and decreased nutrition efficiency were described, but the mechanisms underlying these effects on feeding behavior are not yet totally understood. Swallowing is a major motor component of ingestive behavior which allows the propulsion of the alimentary bolus from the mouth to the esophagus. To better understand DON effects on ingestive behaviour, we have studied its effects on rhythmic swallowing in the rat, after intravenous and central administration. Repetitive electrical stimulation of the superior laryngeal nerve or of the tractus solitarius, induces rhythmic swallowing that can be recorded using electromyographic electrodes inserted in sublingual muscles. Here we provide the first demonstration that, after intravenous and central administration, DON strongly inhibits the swallowing reflex with a short latency and in a dose dependent manner. Moreover, using c-Fos staining, a strong neuronal activation was observed in the solitary tract nucleus which contains the central pattern generator of swallowing and in the area postrema after DON intravenous injection. Our data show that DON modifies swallowing and interferes with central neuronal networks dedicated to food intake regulation.
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Heterogeneous vascular permeability and alternative diffusion barrier in sensory circumventricular organs of adult mouse brain. Cell Tissue Res 2015; 363:497-511. [PMID: 26048259 DOI: 10.1007/s00441-015-2207-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 04/23/2015] [Indexed: 12/22/2022]
Abstract
Fenestrated capillaries of the sensory circumventricular organs (CVOs), including the organum vasculosum of the lamina terminalis, the subfornical organ and the area postrema, lack completeness of the blood-brain barrier (BBB) to sense a variety of blood-derived molecules and to convey the information into other brain regions. We examine the vascular permeability of blood-derived molecules and the expression of tight-junction proteins in sensory CVOs. The present tracer assays revealed that blood-derived dextran 10 k (Dex10k) having a molecular weight (MW) of 10,000 remained in the perivascular space between the inner and outer basement membranes, but fluorescein isothiocyanate (FITC; MW: 389) and Dex3k (MW: 3000) diffused into the parenchyma. The vascular permeability of FITC was higher at central subdivisions than at distal subdivisions. Neither FITC nor Dex3k diffused beyond the dense network of glial fibrillar acidic protein (GFAP)-positive astrocytes/tanycytes. The expression of tight-junction proteins such as occludin, claudin-5 and zonula occludens-1 (ZO-1) was undetectable at the central subdivisions of the sensory CVOs but some was expressed at the distal subdivisions. Electron microscopic observation showed that capillaries were surrounded with numerous layers of astrocyte processes and dendrites. The expression of occludin and ZO-1 was also observed as puncta on GFAP-positive astrocytes/tanycytes of the sensory CVOs. Our study thus demonstrates the heterogeneity of vascular permeability and expression of tight-junction proteins and indicates that the outer basement membrane and dense astrocyte/tanycyte connection are possible alternative mechanisms for a diffusion barrier of blood-derived molecules, instead of the BBB.
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43
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Vascular endothelial growth factor-dependent angiogenesis and dynamic vascular plasticity in the sensory circumventricular organs of adult mouse brain. Cell Tissue Res 2015; 359:865-84. [DOI: 10.1007/s00441-014-2080-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/25/2014] [Indexed: 12/11/2022]
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44
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Nakano Y, Furube E, Morita S, Wanaka A, Nakashima T, Miyata S. Astrocytic TLR4 expression and LPS-induced nuclear translocation of STAT3 in the sensory circumventricular organs of adult mouse brain. J Neuroimmunol 2015; 278:144-58. [DOI: 10.1016/j.jneuroim.2014.12.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/13/2014] [Accepted: 12/13/2014] [Indexed: 12/26/2022]
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45
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Edebali N, Tekin IÖ, Açıkgöz B, Açıkgöz S, Barut F, Sevinç N, Sümbüloğlu V. Apoptosis and necrosis in the circumventricular organs after experimental subarachnoid hemorrhage as detected with annexin V and caspase 3 immunostaining. Neurol Res 2014; 36:1114-20. [PMID: 25137492 DOI: 10.1179/1743132814y.0000000437] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES The circumventricular organs (CVOs) are essential for most autonomic and endocrine functions. Trauma and bleeding can affect their function. The aim of this study was to investigate apoptosis and necrosis in CVOs in the early period after experimental subarachnoid hemorrhage (SAH) in rats, using annexin V affinity and caspase 3 immunostaining. METHODS Three experimental groups were used: Days 1 and 2 after SAH, and a control group, seven Wistar albino rats each. Subarachnoid hemorrhage was accomplished by transclival basilar artery puncture. Rats were perfused with 0.9% NaCl and 0·1M phosphate buffer pH 7.4 until heart stoppage. Apoptosis and necrosis in CVOs were measured by flow cytometry with annexin V staining, and by caspase 3 immunostaining. RESULTS Apoptosis in the organum vasculosum lamina terminalis (OVLT), median eminence (ME), and area postrema (AP) was significantly higher in the Day 1 group than in the control group. Apoptosis in the subfornicial organ (SFO), OVLT, ME, and AP was significantly higher in the Day 2 group than in the control group. There were significant differences between the Day 1 and Day 2 groups, except for AP. Necrosis in SFO and OVLT was significantly higher in the Day 2 group than in the Day 1 or control groups, whereas necrosis in the ME and AP did not differ between the three groups. Caspase 3-positive cell density was more intense in the Day 2 group than in the Day 1 and control groups. DISCUSSION Prevention of apoptosis may potentially improve impaired functions of CVOs after SAH.
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46
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ENaC γ-expressing astrocytes in the circumventricular organs, white matter, and ventral medullary surface: sites for Na+ regulation by glial cells. J Chem Neuroanat 2013; 53:72-80. [PMID: 24145067 DOI: 10.1016/j.jchemneu.2013.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 10/02/2013] [Indexed: 12/19/2022]
Abstract
Using a double immunofluorescence procedure, we report the discovery of a novel group of fibrous astrocytes that co-express epithelial sodium channel (ENaC) γ-subunit protein along with glial acidic fibrillary protein (GFAP). These cells are concentrated along the borders of the sensory circumventricular organs (CVOs), embedded in the white matter (e.g., optic nerve/chiasm, anterior commissure, corpus callosum, pyramidal tract) and are components of the pia mater. In the CVOs, a compact collection of ENaC γ-immunoreactive glial fibers form the lamina terminalis immediately rostral to the organum vasculosum of the lamina terminalis (OVLT). Astrocyte processes can be traced into the median preoptic nucleus - a region implicated in regulation of sodium homeostasis. In the subfornical organ (SFO), ENaC γ-GFAP astrocytes lie in its lateral border, but not in the ventromedial core. In the area postrema (AP), a dense ENaC γ-GFAP glial fibers form the interface between the AP and nucleus tractus solitarius; this area is termed the subpostremal region. Antibodies against the ENaC α- or β-subunit proteins do not immunostain these regions. In contrast, the antibodies against the ENaC γ-subunit protein react weakly with neuronal cell bodies in the CVOs. Besides affecting glial-neural functions in the CVOs, the astrocytes found in the white matter may affect saltatory nerve conduction, serving as a sodium buffer. The ENaC γ-expressing astrocytes of the ventral medulla send processes into the raphe pallidus which intermingle with the serotoninergic (5-HT) neurons found in this region as well as with the other nearby 5-HT neurons distributed along ventral medullary surface.
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Willis CL, Camire RB, Brule SA, Ray DE. Partial recovery of the damaged rat blood-brain barrier is mediated by adherens junction complexes, extracellular matrix remodeling and macrophage infiltration following focal astrocyte loss. Neuroscience 2013; 250:773-85. [PMID: 23845748 PMCID: PMC4002262 DOI: 10.1016/j.neuroscience.2013.06.061] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/13/2013] [Accepted: 06/27/2013] [Indexed: 12/21/2022]
Abstract
Blood-brain barrier (BBB) dysfunction is a feature of many neurodegenerative disorders. The mechanisms and interactions between astrocytes, extracellular matrix and vascular endothelial cells in regulating the mature BBB are poorly understood. We have previously shown that transitory glial fibrillary acidic protein (GFAP)-astrocyte loss, induced by the systemic administration of 3-chloropropanediol, leads to reversible disruption of tight junction complexes and BBB integrity to a range of markers. However, early restoration of BBB integrity to dextran (10-70 kDa) and fibrinogen was seen in the absence of paracellular tight junction proteins claudin-5 and occludin. In the present study we show that in the GFAP-astrocyte-lesioned rat inferior colliculus, paracellular expression of adherens junction proteins (vascular endothelial (VE)-cadherin and β-catenin) was maintained in vascular endothelial cells that lacked paracellular claudin-5 expression and which showed reversible post-translational occludin modification. Claudin-1 expression paralleled the loss and recovery of claudin-5, while claudin-3 or -12 immunoreactivity was not detected. In addition, the extracellular matrix, as visualized by laminin and fibronectin, underwent extensive reversible remodeling and perivascular CD169 macrophages become abundant throughout the lesioned inferior colliculus. At a time that GFAP-astrocytes repopulated the lesion area and tight junction proteins were returned to paracellular domains, the extracellular matrix and leukocyte profiles normalized and resembled profiles seen in control tissue. This study supports the hypothesis that a combination of paracellular adherens junctional proteins, remodeled basement membrane and the presence of perivascular leukocytes provide a temporary barrier to limit the extravasation of macromolecules and potentially neurotoxic substances into the brain parenchyma until tight junction proteins are restored to paracellular domains.
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Affiliation(s)
- C L Willis
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, 11 Hills Beach Road, Biddeford, ME 04005, USA.
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48
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Morita S, Hourai A, Miyata S. Changes in pericytic expression of NG2 and PDGFRB and vascular permeability in the sensory circumventricular organs of adult mouse by osmotic stimulation. Cell Biochem Funct 2013; 32:51-61. [PMID: 23629811 DOI: 10.1002/cbf.2971] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 02/22/2013] [Accepted: 02/25/2013] [Indexed: 01/27/2023]
Abstract
The blood-brain barrier (BBB) is a barrier that prevents free access of blood-derived substances to the brain through the tight junctions and maintains a specialized brain environment. Circumventricular organs (CVOs) lack the typical BBB. The fenestrated vasculature of the sensory CVOs, including the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO) and area postrema (AP), allows parenchyma cells to sense a variety of blood-derived information, including osmotic ones. In the present study, we utilized immunohistochemistry to examine changes in the expression of NG2 and platelet-derived growth factor receptor beta (PDGFRB) in the OVLT, SFO and AP of adult mice during chronic osmotic stimulation. The expression of NG2 and PDGFRB was remarkably prominent in pericytes, although these angiogenesis-associated proteins are highly expressed at pericytes of developing immature vasculature. The chronic salt loading prominently increased the expression of NG2 in the OVLT and SFO and that of PDGFRB in the OVLT, SFO and AP. The vascular permeability of low-molecular-mass tracer fluorescein isothiocyanate was increased significantly by chronic salt loading in the OVLT and SFO but not AP. In conclusion, the present study demonstrates changes in pericyte expression of NG2 and PDGFRB and vascular permeability in the sensory CVOs by chronic osmotic stimulation, indicating active participation of the vascular system in osmotic homeostasis.
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Affiliation(s)
- Shoko Morita
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan; Department of Anatomy and Neuroscience, Faculty of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, Japan
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49
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Mannari T, Morita S, Furube E, Tominaga M, Miyata S. Astrocytic TRPV1 ion channels detect blood-borne signals in the sensory circumventricular organs of adult mouse brains. Glia 2013; 61:957-71. [PMID: 23468425 DOI: 10.1002/glia.22488] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 01/02/2013] [Accepted: 01/29/2013] [Indexed: 01/12/2023]
Abstract
The circumventricular organs (CVOs), including the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), and area postrema (AP) sense a variety of blood-borne molecules because they lack typical blood-brain barrier. Though a few signaling pathways are known, it is not known how endogenous ligands for transient receptor potential vanilloid receptor 1 ion channel (TRPV1) are sensed in the CVOs. In this study, we aimed to examine whether or not astrocytic TRPV1 senses directly blood-borne molecules in the OVLT, SFO, and AP of adult mice. The reverse transcription-polymerase chain reaction and Western analysis revealed the expression of TRPV1 in the CVOs. Confocal microscopic immunohistochemistry further showed that TRPV1 was localized prominently at thick cellular processes of astrocytes rather than fine cellular processes and cell bodies. TRPV1-expressing cellular processes of astrocytes surrounded the vasculature to constitute dense networks. The expression of TRPV1 was also found at neuronal dendrites but not somata in the CVOs. The intravenous administration of a TRPV1 agonist resiniferatoxin (RTX) prominently induced Fos expression at astrocytes in the OVLT, SFO, and AP and neurons in adjacent related nuclei of the median preoptic nuclei (MnPO) and nucleus of the solitary tract (Sol) of wild-type but not TRPV1-knockout mice. The intracerebroventricular infusion of RTX induced Fos expression at both astrocytes and neurons in the CVOs, MnPO, and Sol. Thus, this study demonstrates that blood-borne molecules are sensed directly by astrocytic TRPV1 of the CVOs in adult mammalians.
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Affiliation(s)
- Tetsuya Mannari
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
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50
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Morita S, Miyata S. Accessibility of low-molecular-mass molecules to the median eminence and arcuate hypothalamic nucleus of adult mouse. Cell Biochem Funct 2013; 31:668-77. [PMID: 23348371 DOI: 10.1002/cbf.2953] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 12/13/2012] [Accepted: 12/21/2012] [Indexed: 12/14/2022]
Abstract
Blood-derived molecules are able to access to the median eminence (ME) and arcuate hypothalamic nucleus (Arc) due to the lack of the blood-brain barrier. In the present study, we examined the accessibility of low-molecular-mass (LMM) molecules into parenchyma in the ME and Arc of adult mice by administration of Dextran 3000 (Dex3k), Dex10k, Evans blue (EB) and fluorescein isothiocyanate (FITC). In the external zone of the ME, the fluorescence of Dex3k, EB and FITC tracers generated an intensity gradient from fenestrated capillary, but that of Dex10k was detected only between the inner and outer basement membrane of pericapillary space. The fluorescence of FITC in the external zone of the ME was closely associated with axonal terminals and surrounded by cellular processes of tanycytes-like cells and astrocytes. In the ependymal/internal zone of the ME and Arc, the fluorescence of all LMM tracers was seen at tanycytes-like cells and neurons. The fluorescence of EB and FITC in these regions was not detected when brains were fixed during or before the administration of tracers. The inhomogeneity of accessibility for fluorescent tracers depended on routes for tracer administration. Thus, the present study indicates that the accessibility of LMM blood-derived molecules to parenchyma depends on fenestration of the capillary in the external zone of the ME and active transport of ependymal cells in the ependymal/internal zone of the ME and Arc.
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Affiliation(s)
- Shoko Morita
- Department of Anatomy & Neuroscience, Nara Medical University840 Shijyo-cho, Kashihara City, Nara, 634-8521, Japan
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