1
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Dadwal S, Heneka MT. Microglia heterogeneity in health and disease. FEBS Open Bio 2024; 14:217-229. [PMID: 37945346 PMCID: PMC10839410 DOI: 10.1002/2211-5463.13735] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/12/2023] [Accepted: 11/08/2023] [Indexed: 11/12/2023] Open
Abstract
Microglia, the resident immune cells of the central nervous system (CNS), have received significant attention due to their critical roles in maintaining brain homeostasis and mediating cerebral immune responses. Understanding the origin of microglia has been a subject of great interest, and emerging evidence suggests that microglia consist of multiple subpopulations with unique molecular and functional characteristics. These subpopulations of microglia may exhibit specialized roles in response to different environmental cues as in disease conditions. The newfound understanding of microglial heterogeneity has significant implications for elucidating their roles in both physiological and pathological conditions. In the context of disease, microglia have been studied rigorously as they play a very important role in neuroinflammation. Dysregulated microglial activation and function contribute to chronic inflammation. Further exploration of microglial heterogeneity and their interactions with other cell types in the CNS will undoubtedly pave the way to novel therapeutic strategies targeting microglia-mediated pathologies. In this review, we discuss the latest advances in the field of microglia research, focusing specifically on the origin and subpopulations of microglia, the populations of microglia types in the brains of patients with neurodegenerative diseases, and how microglia are regulated in the healthy CNS.
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Affiliation(s)
- Shilauni Dadwal
- Luxembourg Centre for Systems BiomedicineUniversity of LuxembourgBelvalLuxembourg
| | - Michael T. Heneka
- Luxembourg Centre for Systems BiomedicineUniversity of LuxembourgBelvalLuxembourg
- Division of Infectious Diseases and ImmunologyUniversity of Massachusetts Medical SchoolWorcesterMAUSA
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2
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Harry GJ. Developmental Associations between Neurovascularization and Microglia Colonization. Int J Mol Sci 2024; 25:1281. [PMID: 38279280 PMCID: PMC10816009 DOI: 10.3390/ijms25021281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/28/2024] Open
Abstract
The temporal and spatial pattern of microglia colonization and vascular infiltration of the nervous system implies critical associated roles in early stages of nervous system development. Adding to existing reviews that cover a broad spectrum of the various roles of microglia during brain development, the current review will focus on the developmental ontogeny and interdependency between the colonization of the nervous system with yolk sac derived macrophages and vascularization. Gaining a better understanding of the timing and the interdependency of these two processes will significantly contribute to the interpretation of data generated regarding alterations in either process during early development. Additionally, such knowledge should provide a framework for understanding the influence of the early gestational environmental and the impact of genetics, disease, disorders, or exposures on the early developing nervous system and the potential for long-term and life-time effects.
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Affiliation(s)
- G Jean Harry
- Mechanistic Toxicology Branch, Division of Translational Toxicology, National Institute Environmental Health Sciences, 111 T.W. Alexander Drive, Research Triangle Park, Durham, NC 27709, USA
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3
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Dermitzakis I, Manthou ME, Meditskou S, Tremblay MÈ, Petratos S, Zoupi L, Boziki M, Kesidou E, Simeonidou C, Theotokis P. Origin and Emergence of Microglia in the CNS-An Interesting (Hi)story of an Eccentric Cell. Curr Issues Mol Biol 2023; 45:2609-2628. [PMID: 36975541 PMCID: PMC10047736 DOI: 10.3390/cimb45030171] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/19/2023] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
Microglia belong to tissue-resident macrophages of the central nervous system (CNS), representing the primary innate immune cells. This cell type constitutes ~7% of non-neuronal cells in the mammalian brain and has a variety of biological roles integral to homeostasis and pathophysiology from the late embryonic to adult brain. Its unique identity that distinguishes its "glial" features from tissue-resident macrophages resides in the fact that once entering the CNS, it is perennially exposed to a unique environment following the formation of the blood-brain barrier. Additionally, tissue-resident macrophage progenies derive from various peripheral sites that exhibit hematopoietic potential, and this has resulted in interpretation issues surrounding their origin. Intensive research endeavors have intended to track microglial progenitors during development and disease. The current review provides a corpus of recent evidence in an attempt to disentangle the birthplace of microglia from the progenitor state and underlies the molecular elements that drive microgliogenesis. Furthermore, it caters towards tracking the lineage spatiotemporally during embryonic development and outlining microglial repopulation in the mature CNS. This collection of data can potentially shed light on the therapeutic potential of microglia for CNS perturbations across various levels of severity.
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Affiliation(s)
- Iasonas Dermitzakis
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Maria Eleni Manthou
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Soultana Meditskou
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Steven Petratos
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Lida Zoupi
- Centre for Discovery Brain Sciences & Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Marina Boziki
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece
| | - Evangelia Kesidou
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece
- Laboratory of Experimental Physiology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Constantina Simeonidou
- Laboratory of Experimental Physiology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Paschalis Theotokis
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece
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4
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Cuadros MA, Sepulveda MR, Martin-Oliva D, Marín-Teva JL, Neubrand VE. Microglia and Microglia-Like Cells: Similar but Different. Front Cell Neurosci 2022; 16:816439. [PMID: 35197828 PMCID: PMC8859783 DOI: 10.3389/fncel.2022.816439] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/17/2022] [Indexed: 12/12/2022] Open
Abstract
Microglia are the tissue-resident macrophages of the central nervous parenchyma. In mammals, microglia are thought to originate from yolk sac precursors and posteriorly maintained through the entire life of the organism. However, the contribution of microglial cells from other sources should also be considered. In addition to “true” or “bona-fide” microglia, which are of embryonic origin, the so-called “microglia-like cells” are hematopoietic cells of bone marrow origin that can engraft the mature brain mainly under pathological conditions. These cells implement great parts of the microglial immune phenotype, but they do not completely adopt the “true microglia” features. Because of their pronounced similarity, true microglia and microglia-like cells are usually considered together as one population. In this review, we discuss the origin and development of these two distinct cell types and their differences. We will also review the factors determining the appearance and presence of microglia-like cells, which can vary among species. This knowledge might contribute to the development of therapeutic strategies aiming at microglial cells for the treatment of diseases in which they are involved, for example neurodegenerative disorders like Alzheimer’s and Parkinson’s diseases.
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Affiliation(s)
- Miguel A Cuadros
- Department of Cell Biology, Faculty of Science, University of Granada, Granada, Spain
| | - M Rosario Sepulveda
- Department of Cell Biology, Faculty of Science, University of Granada, Granada, Spain
| | - David Martin-Oliva
- Department of Cell Biology, Faculty of Science, University of Granada, Granada, Spain
| | - José L Marín-Teva
- Department of Cell Biology, Faculty of Science, University of Granada, Granada, Spain
| | - Veronika E Neubrand
- Department of Cell Biology, Faculty of Science, University of Granada, Granada, Spain
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5
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Maternal immune activation induces sustained changes in fetal microglia motility. Sci Rep 2020; 10:21378. [PMID: 33288794 PMCID: PMC7721716 DOI: 10.1038/s41598-020-78294-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 11/20/2020] [Indexed: 12/17/2022] Open
Abstract
Maternal infection or inflammation causes abnormalities in brain development associated with subsequent cognitive impairment and in an increased susceptibility to schizophrenia and autism spectrum disorders. Maternal immune activation (MIA) and increases in serum cytokine levels mediates this association via effects on the fetal brain, and microglia can respond to maternal immune status, but consensus on how microglia may respond is lacking and no-one has yet examined if microglial process motility is impaired. In this study we investigated how MIA induced at two different gestational ages affected microglial properties at different developmental stages. Immune activation in mid-pregnancy increased IL-6 expression in embryonic microglia, but failed to cause any marked changes in morphology either at E18 or postnatally. In contrast MIA, particularly when induced earlier (at E12), caused sustained alterations in the patterns of microglial process motility and behavioral deficits. Our research has identified an important microglial property that is altered by MIA and which may contribute to the underlying pathophysiological mechanisms linking maternal immune status to subsequent risks for cognitive disease.
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6
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A Developmental Analysis of Juxtavascular Microglia Dynamics and Interactions with the Vasculature. J Neurosci 2020; 40:6503-6521. [PMID: 32661024 DOI: 10.1523/jneurosci.3006-19.2020] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 11/21/2022] Open
Abstract
Microglia, a resident CNS macrophage, are dynamic cells, constantly extending and retracting their processes as they contact and functionally regulate neurons and other glial cells. There is far less known about microglia-vascular interactions, particularly under healthy steady-state conditions. Here, we use the male and female mouse cerebral cortex to show that a higher percentage of microglia associate with the vasculature during the first week of postnatal development compared with older ages and that the timing of these associations is dependent on the fractalkine receptor (CX3CR1). Similar developmental microglia-vascular associations were detected in the human brain. Using live imaging in mice, we found that juxtavascular microglia migrated when microglia are actively colonizing the cortex and became stationary by adulthood to occupy the same vascular space for nearly 2 months. Further, juxtavascular microglia at all ages associate with vascular areas void of astrocyte endfeet, and the developmental shift in microglial migratory behavior along vessels corresponded to when astrocyte endfeet more fully ensheath vessels. Together, our data provide a comprehensive assessment of microglia-vascular interactions. They support a mechanism by which microglia use the vasculature to migrate within the developing brain parenchyma. This migration becomes restricted on the arrival of astrocyte endfeet such that juxtavascular microglia become highly stationary and stable in the mature cortex.SIGNIFICANCE STATEMENT We report the first extensive analysis of juxtavascular microglia in the healthy, developing, and adult brain. Live imaging revealed that juxtavascular microglia within the cortex are highly motile and migrate along vessels as they are colonizing cortical regions. Using confocal, expansion, super-resolution, and electron microscopy, we determined that microglia associate with the vasculature at all ages in areas lacking full astrocyte endfoot coverage and motility of juxtavascular microglia ceases as astrocyte endfeet more fully ensheath the vasculature. Our data lay the fundamental groundwork to investigate microglia-astrocyte cross talk and juxtavascular microglial function in the healthy and diseased brain. They further provide a potential mechanism by which vascular interactions facilitate microglial colonization of the brain to later regulate neural circuit development.
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7
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Mass E. Delineating the origins, developmental programs and homeostatic functions of tissue-resident macrophages. Int Immunol 2019; 30:493-501. [PMID: 29986024 DOI: 10.1093/intimm/dxy044] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 07/04/2018] [Indexed: 12/22/2022] Open
Abstract
A literature covering 150 years of research indicates that macrophages are a diverse family of professional phagocytes that continuously explore their environment, recognize and scavenge pathogens, unfit cells, cell debris as well as metabolites, and produce a large range of bioactive molecules and growth factors. A new paradigm suggests that most tissue-resident macrophages originate from fetal precursors that colonize developing organs and self-maintain independently of bone marrow-derived cells throughout life. The differentiation of these precursors is driven by a core macrophage transcriptional program and immediately followed by their specification through expression of tissue-specific transcriptional regulators early during embryogenesis. Despite our increasing understanding of ontogeny and genetic programs that shape differentiation processes and functions of macrophages, the precise developmental trajectories of tissue-resident macrophages remain undefined. Here, I review current models of fetal hematopoietic waves, possible routes of macrophage development and their roles during homeostasis. Further, transgenic mouse models are discussed providing a toolset to study the developmentally and functionally distinct arms of the phagocyte system in vivo.
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Affiliation(s)
- Elvira Mass
- Developmental Biology of the Innate Immune System, LIMES-Institute, University of Bonn, Bonn, Germany
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8
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Cool T, Forsberg EC. Chasing Mavericks: The quest for defining developmental waves of hematopoiesis. Curr Top Dev Biol 2019; 132:1-29. [PMID: 30797507 DOI: 10.1016/bs.ctdb.2019.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hematopoiesis is the process by which mature blood and immune cells are produced from hematopoietic stem and progenitor cells (HSCs and HSPCs). The last several decades of research have shed light on the origin of HSCs, as well as the heterogeneous pools of fetal progenitors that contribute to lifelong hematopoiesis. The overarching concept that hematopoiesis occurs in dynamic, overlapping waves throughout development, with each wave contributing to both continuous and developmentally limited cell types, has been solidified over the years. However, recent advances in our ability to track the production of hematopoietic cells in vivo have challenged several long-held dogmas on the origin and persistence of distinct hematopoietic cell types. In this review, we highlight emerging concepts in hematopoietic development and identify unanswered questions.
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Affiliation(s)
- Taylor Cool
- Institute for the Biology of Stem Cells, Program in Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - E Camilla Forsberg
- Institute for the Biology of Stem Cells, Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, CA, United States.
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9
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Abstract
Research during the last decade has generated numerous insights on the presence, phenotype, and function of myeloid cells in cardiovascular organs. Newer tools with improved detection sensitivities revealed sizable populations of tissue-resident macrophages in all major healthy tissues. The heart and blood vessels contain robust numbers of these cells; for instance, 8% of noncardiomyocytes in the heart are macrophages. This number and the cell's phenotype change dramatically in disease conditions. While steady-state macrophages are mostly monocyte independent, macrophages residing in the inflamed vascular wall and the diseased heart derive from hematopoietic organs. In this review, we will highlight signals that regulate macrophage supply and function, imaging applications that can detect changes in cell numbers and phenotype, and opportunities to modulate cardiovascular inflammation by targeting macrophage biology. We strive to provide a systems-wide picture, i.e., to focus not only on cardiovascular organs but also on tissues involved in regulating cell supply and phenotype, as well as comorbidities that promote cardiovascular disease. We will summarize current developments at the intersection of immunology, detection technology, and cardiovascular health.
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Affiliation(s)
- Vanessa Frodermann
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School , Boston, Massachusetts ; and Cardiovascular Research Center, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Matthias Nahrendorf
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School , Boston, Massachusetts ; and Cardiovascular Research Center, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
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10
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Demy DL, Tauzin M, Lancino M, Le Cabec V, Redd M, Murayama E, Maridonneau-Parini I, Trede N, Herbomel P. Trim33 is essential for macrophage and neutrophil mobilization to developmental or inflammatory cues. J Cell Sci 2017; 130:2797-2807. [PMID: 28724755 DOI: 10.1242/jcs.203471] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 07/10/2017] [Indexed: 01/04/2023] Open
Abstract
Macrophages infiltrate and establish in developing organs from an early stage, often before these have become vascularized. Similarly, leukocytes, in general, can quickly migrate through tissues to any site of wounding. This unique capacity is rooted in their characteristic amoeboid motility, the genetic basis of which is poorly understood. Trim33 (also known as Tif1-γ), a nuclear protein that associates with specific DNA-binding transcription factors to modulate gene expression, has been found to be mainly involved in hematopoiesis and gene regulation mediated by TGF-β. Here, we have discovered that in Trim33-deficient zebrafish embryos, primitive macrophages are unable to colonize the central nervous system to become microglia. Moreover, both macrophages and neutrophils of Trim33-deficient embryos display a reduced basal mobility within interstitial tissues, and a profound lack of a response to inflammatory recruitment signals, including local bacterial infections. Correlatively, Trim33-deficient mouse bone marrow-derived macrophages display a strongly reduced three-dimensional amoeboid mobility in fibrous collagen gels. The transcriptional regulator Trim33 is thus revealed as being essential for the navigation of macrophages and neutrophils towards developmental or inflammatory cues within vertebrate tissues.
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Affiliation(s)
- Doris Lou Demy
- Institut Pasteur, Department of Developmental & Stem Cell Biology, 25 rue du Dr Roux, 75015 Paris, France.,CNRS, UMR3738, 25 rue du Dr Roux, 75015 Paris, France
| | - Muriel Tauzin
- Institut Pasteur, Department of Developmental & Stem Cell Biology, 25 rue du Dr Roux, 75015 Paris, France.,CNRS, UMR3738, 25 rue du Dr Roux, 75015 Paris, France
| | - Mylène Lancino
- Institut Pasteur, Department of Developmental & Stem Cell Biology, 25 rue du Dr Roux, 75015 Paris, France.,CNRS, UMR3738, 25 rue du Dr Roux, 75015 Paris, France
| | - Véronique Le Cabec
- CNRS UMR5089, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne BP64182, 31077 Toulouse, France.,Université de Toulouse, UPS, IPBS, 31077 Toulouse, France
| | - Michael Redd
- University of Utah, Huntsman Cancer Institute, 2000 Circle of Hope Drive, Salt Lake City, UT 94112, USA
| | - Emi Murayama
- Institut Pasteur, Department of Developmental & Stem Cell Biology, 25 rue du Dr Roux, 75015 Paris, France.,CNRS, UMR3738, 25 rue du Dr Roux, 75015 Paris, France
| | - Isabelle Maridonneau-Parini
- CNRS UMR5089, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne BP64182, 31077 Toulouse, France.,Université de Toulouse, UPS, IPBS, 31077 Toulouse, France
| | - Nikolaus Trede
- University of Utah, Huntsman Cancer Institute, 2000 Circle of Hope Drive, Salt Lake City, UT 94112, USA
| | - Philippe Herbomel
- Institut Pasteur, Department of Developmental & Stem Cell Biology, 25 rue du Dr Roux, 75015 Paris, France .,CNRS, UMR3738, 25 rue du Dr Roux, 75015 Paris, France
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11
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Gerri C, Marín-Juez R, Marass M, Marks A, Maischein HM, Stainier DYR. Hif-1α regulates macrophage-endothelial interactions during blood vessel development in zebrafish. Nat Commun 2017; 8:15492. [PMID: 28524872 PMCID: PMC5493593 DOI: 10.1038/ncomms15492] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 04/01/2017] [Indexed: 12/21/2022] Open
Abstract
Macrophages are known to interact with endothelial cells during developmental and pathological angiogenesis but the molecular mechanisms modulating these interactions remain unclear. Here, we show a role for the Hif-1α transcription factor in this cellular communication. We generated hif-1aa;hif-1ab double mutants in zebrafish, hereafter referred to as hif-1α mutants, and find that they exhibit impaired macrophage mobilization from the aorta-gonad-mesonephros (AGM) region as well as angiogenic defects and defective vascular repair. Importantly, macrophage ablation is sufficient to recapitulate the vascular phenotypes observed in hif-1α mutants, revealing for the first time a macrophage-dependent angiogenic process during development. Further substantiating our observations of vascular repair, we find that most macrophages closely associated with ruptured blood vessels are Tnfα-positive, a key feature of classically activated macrophages. Altogether, our data provide genetic evidence that Hif-1α regulates interactions between macrophages and endothelial cells starting with the mobilization of macrophages from the AGM. The molecular mechanism regulating macrophage interaction with endothelial cells during development is unclear. Here, the authors show that in zebrafish mutation of hypoxia-inducible factor-1α impairs macrophage mobilization from the aorta-gonad-mesonephros, causing defects in angiogenesis and vessel repair.
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Affiliation(s)
- Claudia Gerri
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Rubén Marín-Juez
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Michele Marass
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Alora Marks
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Hans-Martin Maischein
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Didier Y R Stainier
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
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12
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Wałajtys-Rode E, Dzik JM. Monocyte/Macrophage: NK Cell Cooperation-Old Tools for New Functions. Results Probl Cell Differ 2017; 62:73-145. [PMID: 28455707 DOI: 10.1007/978-3-319-54090-0_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Monocyte/macrophage and natural killer (NK) cells are partners from a phylogenetic standpoint of innate immune system development and its evolutionary progressive interaction with adaptive immunity. The equally conservative ways of development and differentiation of both invertebrate hemocytes and vertebrate macrophages are reviewed. Evolutionary conserved molecules occurring in macrophage receptors and effectors have been inherited by vertebrates after their common ancestor with invertebrates. Cytolytic functions of mammalian NK cells, which are rooted in immune cells of invertebrates, although certain NK cell receptors (NKRs) are mammalian new events, are characterized. Broad heterogeneity of macrophage and NK cell phenotypes that depends on surrounding microenvironment conditions and expression profiles of specific receptors and activation mechanisms of both cell types are discussed. The particular tissue specificity of macrophages and NK cells, as well as their plasticity and mechanisms of their polarization to different functional subtypes have been underlined. The chapter summarized studies revealing the specific molecular mechanisms and regulation of NK cells and macrophages that enable their highly specific cross-cooperation. Attention is given to the evolving role of human monocyte/macrophage and NK cell interaction in pathogenesis of hypersensitivity reaction-based disorders, including autoimmunity, as well as in cancer surveillance and progression.
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Affiliation(s)
- Elżbieta Wałajtys-Rode
- Faculty of Chemistry, Department of Drug Technology and Biotechnology, Warsaw University of Technology, Noakowskiego 3 Str, 00-664, Warsaw, Poland.
| | - Jolanta M Dzik
- Faculty of Agriculture and Biology, Department of Biochemistry, Warsaw University of Life Sciences-SGGW, Warsaw, Poland
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13
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Reemst K, Noctor SC, Lucassen PJ, Hol EM. The Indispensable Roles of Microglia and Astrocytes during Brain Development. Front Hum Neurosci 2016; 10:566. [PMID: 27877121 PMCID: PMC5099170 DOI: 10.3389/fnhum.2016.00566] [Citation(s) in RCA: 336] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/25/2016] [Indexed: 01/17/2023] Open
Abstract
Glia are essential for brain functioning during development and in the adult brain. Here, we discuss the various roles of both microglia and astrocytes, and their interactions during brain development. Although both cells are fundamentally different in origin and function, they often affect the same developmental processes such as neuro-/gliogenesis, angiogenesis, axonal outgrowth, synaptogenesis and synaptic pruning. Due to their important instructive roles in these processes, dysfunction of microglia or astrocytes during brain development could contribute to neurodevelopmental disorders and potentially even late-onset neuropathology. A better understanding of the origin, differentiation process and developmental functions of microglia and astrocytes will help to fully appreciate their role both in the developing as well as in the adult brain, in health and disease.
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Affiliation(s)
- Kitty Reemst
- Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
| | - Stephen C. Noctor
- Department of Psychiatry and Behavioral Sciences, UC Davis MIND InstituteSacramento, CA, USA
| | - Paul J. Lucassen
- Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
| | - Elly M. Hol
- Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
- Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center UtrechtUtrecht, Netherlands
- Netherlands Institute for NeuroscienceAmsterdam, Netherlands
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14
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Tissue-Resident Macrophage Ontogeny and Homeostasis. Immunity 2016; 44:439-449. [PMID: 26982352 DOI: 10.1016/j.immuni.2016.02.024] [Citation(s) in RCA: 1106] [Impact Index Per Article: 138.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 02/15/2016] [Accepted: 02/23/2016] [Indexed: 01/17/2023]
Abstract
Defining the origins and developmental pathways of tissue-resident macrophages should help refine our understanding of the role of these cells in various disease settings and enable the design of novel macrophage-targeted therapies. In recent years the long-held belief that macrophage populations in the adult are continuously replenished by monocytes from the bone marrow (BM) has been overturned with the advent of new techniques to dissect cellular ontogeny. The new paradigm suggests that several tissue-resident macrophage populations are seeded during waves of embryonic hematopoiesis and self-maintain independently of BM contribution during adulthood. However, the exact nature of the embryonic progenitors that give rise to adult tissue-resident macrophages is still debated, and the mechanisms enabling macrophage population maintenance in the adult are undefined. Here, we review the emergence of these concepts and discuss current controversies and future directions in macrophage biology.
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15
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Shemer A, Erny D, Jung S, Prinz M. Microglia Plasticity During Health and Disease: An Immunological Perspective. Trends Immunol 2015; 36:614-624. [DOI: 10.1016/j.it.2015.08.003] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/02/2015] [Accepted: 08/12/2015] [Indexed: 12/23/2022]
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16
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Homeostasis of Microglia in the Adult Brain: Review of Novel Microglia Depletion Systems. Trends Immunol 2015; 36:625-636. [DOI: 10.1016/j.it.2015.08.005] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 01/16/2023]
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17
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Quantitative assessment of angiogenesis, perfused blood vessels and endothelial tip cells in the postnatal mouse brain. Nat Protoc 2014; 10:53-74. [PMID: 25502884 DOI: 10.1038/nprot.2015.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
During development and in various diseases of the CNS, new blood vessel formation starts with endothelial tip cell selection and vascular sprout migration, followed by the establishment of functional, perfused blood vessels. Here we describe a method that allows the assessment of these distinct angiogenic steps together with antibody-based protein detection in the postnatal mouse brain. Intravascular and perivascular markers such as Evans blue (EB), isolectin B4 (IB4) or laminin (LN) are used alongside simultaneous immunofluorescence on the same sections. By using confocal laser-scanning microscopy and stereological methods for analysis, detailed quantification of the 3D postnatal brain vasculature for perfused and nonperfused vessels (e.g., vascular volume fraction, vessel length and number, number of branch points and perfusion status of the newly formed vessels) and characterization of sprouting activity (e.g., endothelial tip cell density, filopodia number) can be obtained. The entire protocol, from mouse perfusion to vessel analysis, takes ∼10 d.
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Monocytes and macrophages: developmental pathways and tissue homeostasis. Nat Rev Immunol 2014; 14:392-404. [DOI: 10.1038/nri3671] [Citation(s) in RCA: 1159] [Impact Index Per Article: 115.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
Microglia are critical nervous system-specific cells influencing brain development, maintenance of the neural environment, response to injury, and repair. They contribute to neuronal proliferation and differentiation, pruning of dying neurons, synaptic remodeling and clearance of debris and aberrant proteins. Colonization of the brain occurs during gestation with an expansion following birth with localization stimulated by programmed neuronal death, synaptic pruning, and axonal degeneration. Changes in microglia phenotype relate to cellular processes including specific neurotransmitter, pattern recognition, or immune-related receptor activation. Upon activation, microglia cells have the capacity to release a number of substances, e.g., cytokines, chemokines, nitric oxide, and reactive oxygen species, which could be detrimental or beneficial to the surrounding cells. With aging, microglia shift their morphology and may display diminished capacity for normal functions related to migration, clearance, and the ability to shift from a pro-inflammatory to an anti-inflammatory state to regulate injury and repair. This shift in microglia potentially contributes to increased susceptibility and neurodegeneration as a function of age. In the current review, information is provided on the colonization of the brain by microglia, the expression of various pattern recognition receptors to regulate migration and phagocytosis, and the shift in related functions that occur in normal aging.
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Affiliation(s)
- G Jean Harry
- National Toxicology Program Laboratory, National Institute of Environmental Health Sciences, MD C1-04, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA.
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Hellwig S, Heinrich A, Biber K. The brain's best friend: microglial neurotoxicity revisited. Front Cell Neurosci 2013; 7:71. [PMID: 23734099 PMCID: PMC3655268 DOI: 10.3389/fncel.2013.00071] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 04/26/2013] [Indexed: 01/13/2023] Open
Abstract
One long standing aspect of microglia biology was never questioned; their involvement in brain disease. Based on morphological changes (retracted processes and amoeboid shape) that inevitably occur in these cells in case of damage in the central nervous system, microglia in the diseased brain were called “activated.” Because “activated” microglia were always found in direct neighborhood to dead or dying neuron, and since it is known now for more than 20 years that cultured microglia release numerous factors that are able to kill neurons, microglia “activation” was often seen as a neurotoxic process. From an evolutionary point of view, however, it is difficult to understand why an important, mostly post-mitotic and highly vulnerable organ like the brain would host numerous potential killers. This review is aimed to critically reconsider the term microglia neurotoxicity and to discuss experimental problems around microglia biology, that often have led to the conclusion that microglia are neurotoxic cells.
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Affiliation(s)
- Sabine Hellwig
- Department of Psychiatry and Psychotherapy, University Hospital Freiburg Freiburg, Germany
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Ginhoux F, Lim S, Hoeffel G, Low D, Huber T. Origin and differentiation of microglia. Front Cell Neurosci 2013; 7:45. [PMID: 23616747 PMCID: PMC3627983 DOI: 10.3389/fncel.2013.00045] [Citation(s) in RCA: 550] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/30/2013] [Indexed: 12/30/2022] Open
Abstract
Microglia are the resident macrophage population of the central nervous system (CNS). Adequate microglial function is crucial for a healthy CNS. Microglia are not only the first immune sentinels of infection, contributing to both innate and adaptive immune responses locally, but are also involved in the maintenance of brain homeostasis. Emerging data are showing new and fundamental roles for microglia in the control of neuronal proliferation and differentiation, as well as in the formation of synaptic connections. While microglia have been studied for decades, a long history of experimental misinterpretation meant that their true origins remained debated. However, recent studies on microglial origin indicate that these cells in fact arise early during development from progenitors in the embryonic yolk sac (YS) that seed the brain rudiment and, remarkably, appear to persist there into adulthood. Here, we review the history of microglial cells and discuss the latest advances in our understanding of their origin, differentiation, and homeostasis, which provides new insights into their roles in health and disease.
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Affiliation(s)
- Florent Ginhoux
- Singapore Immunology Network, Agency for Science, Technology, and ResearchSingapore
| | - Shawn Lim
- Genome Institute Singapore, Agency for Science, Technology, and ResearchSingapore
| | - Guillaume Hoeffel
- Singapore Immunology Network, Agency for Science, Technology, and ResearchSingapore
| | - Donovan Low
- Singapore Immunology Network, Agency for Science, Technology, and ResearchSingapore
| | - Tara Huber
- Genome Institute Singapore, Agency for Science, Technology, and ResearchSingapore
- Department of Biological Science, National University of SingaporeSingapore
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Gomez Perdiguero E, Schulz C, Geissmann F. Development and homeostasis of "resident" myeloid cells: the case of the microglia. Glia 2012; 61:112-20. [PMID: 22847963 DOI: 10.1002/glia.22393] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 06/26/2012] [Indexed: 12/12/2022]
Abstract
Microglia, macrophages of the central nervous system, play an important role in brain homeostasis. Their origin has been unclear. Recent fate-mapping experiments have established that microglia mostly originate from Myb-independent, FLT3-independent, but PU.1-dependent precursors that express the CSF1-receptor at E8.5 of embryonic development. These precursors are presumably located in the yolk sac (YS) at this time before invading the embryo between E9.5 and E10.5 and colonizing the fetal liver. Indeed, the E14.5 fetal liver contains a large population of Myb-independent YS-derived myeloid cells. This myeloid lineage is distinct from hematopoietic stem cells (HSCs), which require the transcription factor Myb for their development and maintenance. This "yolky" beginning and the independence from conventional HSCs are not unique to microglia. Indeed, several other populations of F4/80-positive macrophages develop also from YS Myb-independent precursors, such as Kupffer cells in the liver, Langerhans cells in the epidermis, and macrophages in the spleen, kidney, pancreas, and lung. Importantly, microglia and the other Myb-independent macrophages persist, at least in part, in adult mice and likely self-renew within their respective tissues of residence, independently of bone marrow HSCs. This suggests the existence of tissue resident macrophage "stem cells" within tissues such as the brain, and opens a new era for the molecular and cellular understanding of myeloid cells responses during acute and chronic inflammation.
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Affiliation(s)
- Elisa Gomez Perdiguero
- Centre for Molecular and Cellular Biology of Inflammation, King's College London, Great Maze Pond, London, United Kingdom
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Ponomarev ED, Veremeyko T, Weiner HL. MicroRNAs are universal regulators of differentiation, activation, and polarization of microglia and macrophages in normal and diseased CNS. Glia 2012; 61:91-103. [PMID: 22653784 DOI: 10.1002/glia.22363] [Citation(s) in RCA: 251] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 12/17/2022]
Abstract
MicroRNAs (miRNAs) are a class of small (∼22 nucleotides) noncoding RNAs involved in the regulation of gene expression at the post-translational level. It is estimated that 30-90% of human genes are regulated by miRNAs, which makes these molecules of great importance for cell growth, activation, and differentiation. Microglia is CNS-resident cells of a myeloid lineage that play an important role in immune surveillance and are actively involved in many neurologic pathologies. Although the exact origin of microglia remains enigmatic, it is established that primitive macrophages from a yolk sac populate the brain and spinal cord in normal conditions throughout development. During various pathological events such as neuroinflammation, bone marrow derived myeloid cells also migrate into the CNS. Within the CNS, both primitive macrophages from the yolk sac and bone marrow derived myeloid cells acquire a specific phenotype upon interaction with other cell types within the CNS microenvironment. The factors that drive differentiation of progenitors into microglia and control the state of activation of microglia and bone marrow-derived myeloid cells within the CNS are not well understood. In this review we will summarize the role of miRNAs during activation and differentiation of myeloid cells. The role of miR-124 in the adaptation of microglia and macrophages to the CNS microenvironment will be further discussed. We will also summarize the role of miRNAs as modulators of activation of microglia and microphages. Finally, we will describe the role of miR-155 and miR-124 in the polarization of macrophages towards classically and alternatively activated phenotypes.
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Affiliation(s)
- Eugene D Ponomarev
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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Abstract
Microglia, the brain's innate immune cell type, are cells of mesodermal origin that populate the central nervous system (CNS) during development. Undifferentiated microglia, also called ameboid microglia, have the ability to proliferate, phagocytose apoptotic cells and migrate long distances toward their final destinations throughout all CNS regions, where they acquire a mature ramified morphological phenotype. Recent studies indicate that ameboid microglial cells not only have a scavenger role during development but can also promote the death of some neuronal populations. In the mature CNS, adult microglia have highly motile processes to scan their territorial domains, and they display a panoply of effects on neurons that range from sustaining their survival and differentiation contributing to their elimination. Hence, the fine tuning of these effects results in protection of the nervous tissue, whereas perturbations in the microglial response, such as the exacerbation of microglial activation or lack of microglial response, generate adverse situations for the organization and function of the CNS. This review discusses some aspects of the relationship between microglial cells and neuronal death/survival both during normal development and during the response to injury in adulthood.
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Pont-Lezica L, Béchade C, Belarif-Cantaut Y, Pascual O, Bessis A. Physiological roles of microglia during development. J Neurochem 2011; 119:901-8. [PMID: 21951310 DOI: 10.1111/j.1471-4159.2011.07504.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In all the species examined thus far, the behavior of microglia during development appears to be highly stereotyped. This reproducibility supports the notion that these cells have a physiological role in development. Microglia are macrophages that migrate from the yolk sac and colonize the central nervous system early during development. The first invading yolk-sac macrophages are highly proliferative and their role has not yet been addressed. At later developmental stages, microglia can be found throughout the brain and tend to preferentially reside at specific locations that are often associated with known developmental processes. Thus, it appears that microglia concentrate in areas of cell death, in proximity of developing blood vessels, in the marginal layer, which contains developing axon fascicles, and in close association with radial glial cells. This review describes the main features of brain colonization by microglia and discusses the possible physiological roles of these cells during development.
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Affiliation(s)
- Lorena Pont-Lezica
- Institut de Biologie de l'Ecole Normale Supérieure, INSERM 1024 - CNRS 8197, Paris, France
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26
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Ginhoux F, Greter M, Leboeuf M, Nandi S, See P, Gokhan S, Mehler MF, Conway SJ, Ng LG, Stanley ER, Samokhvalov IM, Merad M. Fate mapping analysis reveals that adult microglia derive from primitive macrophages. Science 2010; 330:841-5. [PMID: 20966214 DOI: 10.1126/science.1194637] [Citation(s) in RCA: 3431] [Impact Index Per Article: 245.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Microglia are the resident macrophages of the central nervous system and are associated with the pathogenesis of many neurodegenerative and brain inflammatory diseases; however, the origin of adult microglia remains controversial. We show that postnatal hematopoietic progenitors do not significantly contribute to microglia homeostasis in the adult brain. In contrast to many macrophage populations, we show that microglia develop in mice that lack colony stimulating factor-1 (CSF-1) but are absent in CSF-1 receptor-deficient mice. In vivo lineage tracing studies established that adult microglia derive from primitive myeloid progenitors that arise before embryonic day 8. These results identify microglia as an ontogenically distinct population in the mononuclear phagocyte system and have implications for the use of embryonically derived microglial progenitors for the treatment of various brain disorders.
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Affiliation(s)
- Florent Ginhoux
- Department of Gene and Cell Medicine and the Immunology Institute, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA.
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27
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Tissue macrophages act as cellular chaperones for vascular anastomosis downstream of VEGF-mediated endothelial tip cell induction. Blood 2010; 116:829-40. [PMID: 20404134 DOI: 10.1182/blood-2009-12-257832] [Citation(s) in RCA: 780] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Blood vessel networks expand in a 2-step process that begins with vessel sprouting and is followed by vessel anastomosis. Vessel sprouting is induced by chemotactic gradients of the vascular endothelial growth factor (VEGF), which stimulates tip cell protrusion. Yet it is not known which factors promote the fusion of neighboring tip cells to add new circuits to the existing vessel network. By combining the analysis of mouse mutants defective in macrophage development or VEGF signaling with live imaging in zebrafish, we now show that macrophages promote tip cell fusion downstream of VEGF-mediated tip cell induction. Macrophages therefore play a hitherto unidentified and unexpected role as vascular fusion cells. Moreover, we show that there are striking molecular similarities between the pro-angiogenic tissue macrophages essential for vascular development and those that promote the angiogenic switch in cancer, including the expression of the cell-surface proteins TIE2 and NRP1. Our findings suggest that tissue macrophages are a target for antiangiogenic therapies, but that they could equally well be exploited to stimulate tissue vascularization in ischemic disease.
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28
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Streit WJ, Xue QS. Life and death of microglia. J Neuroimmune Pharmacol 2009; 4:371-9. [PMID: 19680817 DOI: 10.1007/s11481-009-9163-5] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Accepted: 06/30/2009] [Indexed: 01/05/2023]
Abstract
The importance of microglial cells in the maintenance of a well-functioning central nervous system (CNS) cannot be overstated. As descendants of the myelomonocytic lineage they are industrious housekeepers and watchful sentries that safeguard a homeostatic environment through a number of mechanisms designed to provide protection of fastidious neurons at all times. Microglia become particularly active after homeostasis has been perturbed by physical injury or other insults and they enter into a state of activation which is determined largely by the nature and severity of the lesion. Microglial activation is the main cellular event in acute neuroinflammation and essential for wound healing in the CNS. Recent studies from this laboratory have been focused on microglia in the aging brain and identified structural abnormalities, termed microglial dystrophy, that are consistent with cell senescence and progress to a form of accidental cell death that is marked by cytoplasmic degeneration and has been termed cytorrhexis. Cytorrhexis of microglia is infrequent in the normally aged human brain and non-detectable in aged rodents, but its occurrence increases dramatically during neurodegenerative conditions, including Alzheimer's disease (AD) in humans and motoneuron disease in transgenic rats. The identification of degenerating microglia has given rise to a novel theory of AD pathogenesis, the microglial dysfunction hypothesis, which views the loss of microglial neuroprotection as a central event in neurodegenerative disease development.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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Tomlinson ML, Garcia-Morales C, Abu-Elmagd M, Wheeler GN. Three matrix metalloproteinases are required in vivo for macrophage migration during embryonic development. Mech Dev 2008; 125:1059-70. [PMID: 18684398 DOI: 10.1016/j.mod.2008.07.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 07/08/2008] [Accepted: 07/09/2008] [Indexed: 11/19/2022]
Abstract
Macrophages are essential in development, repair and pathology of a variety of tissues via their roles in tissue remodelling, wound healing and inflammation. These biological functions are also associated with a number of human diseases, for example tumour associated macrophages have well defined functions in cancer progression. Xenopus embryonic macrophages arise from a haematopoietic stem cell population by direct differentiation and act as the main mechanism of host defence, before lymphoid cells and a circulatory system have developed. This function is conserved in mouse and human development. Macrophages express a number of matrix metalloproteinases (MMPs), which are central to their function. MMPs are a large family of zinc-dependent endoproteases with multiple roles in extracellular matrix remodelling and the modulation of signalling pathways. We have previously shown MMP-7 to be expressed by Xenopus embryonic macrophages. Here we investigate the role of MMP-7 and two other MMPs (MMP-18 and MMP-9) that are also expressed in the migrating macrophages. Using morpholino (MO) mediated knockdown of each of the MMPs we demonstrate that they are necessary for normal macrophage migration in vivo. The loss-of-function effect can be rescued using the specific MMPs, altered to be resistant to morpholinos but not by overexpression of the other MMPs. Double and triple morpholino knockdowns further suggest that these MMPs act combinatorily to promote embryonic macrophage migration. Thus, our results imply that these three MMPs have distinct functions, which together are crucial to mediate macrophage migration in the developing embryo. This demonstrates conclusively that MMPs are required for normal macrophage cell migration in the whole organism.
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Affiliation(s)
- Matthew L Tomlinson
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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30
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Alyahya K, Chen CT, Mangan BG, Gionfriddo JR, Legare ME, Dubielzig RR, Madl JE. Microvessel loss, vascular damage and glutamate redistribution in the retinas of dogs with primary glaucoma. Vet Ophthalmol 2007; 10 Suppl 1:70-7. [DOI: 10.1111/j.1463-5224.2007.00562.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Xu H, Chen M, Mayer EJ, Forrester JV, Dick AD. Turnover of resident retinal microglia in the normal adult mouse. Glia 2007; 55:1189-98. [PMID: 17600341 DOI: 10.1002/glia.20535] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The retina contains two distinct populations of monocyte-derived cells: perivascular cells (macrophages) and parenchymal cells (microglia), important in homeostasis, neuroinflammation, degeneration, and injury. The turnover of these cells in the retina and their repopulation in normal physiological conditions have not been clarified. Bone marrow (BM) cells from EGFP-transgenic mice were adoptively transferred into lethally irradiated normal adult C57BL/6 mice. Eight, 14, and 26 weeks later mice were sacrificed and retinal flatmounts were prepared. Retinal microglia were identified by F4/80, CD45, and Iba-1 immunostaining. BrdU was injected into normal mice for 3-14 days and cell proliferation was examined by confocal microscopy of retinal flatmounts. Few (6.15 +/- 2.02 cells/retina) BrdU(+) cells were detected and of these some coexpressed CD11b (1.67 +/- 0.62 cells/retina) or F4/80 (0.57 +/- 0.30 cells/retina). BM-derived EGFP(+) cells were detected by 8-weeks post-transplantation. By 6 months, all retinal myeloid cells were EGFP(+). Consecutively, donor BM-EGFP(+) cells were demonstrated within the: (1) peripheral and juxtapapillary retina, (2) ganglion cell layer, (3) inner and outer plexiform layers, and (4) photoreceptor layer. EGFP(+) cells within the ganglion layer were amoeboid in shape and F4/80(high)CD45(high)Iba-1(high), whereas cells in the inner and outer plexiform layers were ramified and F4/80(low) CD45(low)Iba-1(low). Perivascular macrophages expressed less F4/80, CD45, and Iba-1 compared with parenchymal microglia. Our results suggest that BM-derived monocyte precursor cells are able to migrate across the BRB and replace retinal microglia/macrophages. The complete replacement of retinal microglia/macrophages takes about 6 months. In situ proliferation was predominantly of nonhemopoetic retinal cells.
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Affiliation(s)
- Heping Xu
- Department of Ophthalmology, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK.
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Grabher C, Cliffe A, Miura K, Hayflick J, Pepperkok R, Rørth P, Wittbrodt J. Birth and life of tissue macrophages and their migration in embryogenesis and inflammation in medaka. J Leukoc Biol 2007; 81:263-71. [PMID: 17046968 DOI: 10.1189/jlb.0806526] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Macrophages detecting and migrating toward sites of injury and infection represent one of the first steps in an immune response. Here we directly image macrophage birth and migration in vivo in transgenic medaka fish. Macrophages are born as frequently dividing, immotile cells with spherical morphology that differentiate into flat, highly motile cells. They retain mitotic activity while spreading over the entire body. Cells follow restricted paths not only in directed migration, but also during patrolling. Along those paths the macrophages rapidly patrol the tissue and respond to wounding and bacterial infection from long distances. Upon injury they increase their speed and migratory persistence. Specifically targeting PI3-kinase isoforms efficiently blocks the wounding response and results in a distinct inhibition of cell motility and chemotaxis. Our study provides in situ insights into the properties of immature and migratory macrophages and presents a unique model to further test modulating compounds in vivo.
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Affiliation(s)
- Clemens Grabher
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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Ueno M, Katayama KI, Yamauchi H, Yasoshima A, Nakayama H, Doi K. Repair process of fetal brain after 5-azacytidine-induced damage. Eur J Neurosci 2006; 24:2758-68. [PMID: 17156202 DOI: 10.1111/j.1460-9568.2006.05161.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The fetal brain is susceptible to many extrinsic stresses. Some of these stresses induce excessive cell death in the prenatal stage, leading to anomalies in the neonatal brain. However, it is unclear how the developing brain responds to and repairs the prenatal tissue damage. We treated pregnant rats on day 13 of gestation with 5-azacytidine, one of the compounds that induces excessive cell death and inhibits proliferation in neural progenitor cells, to damage the fetal brain, and investigated the repair process up to 60 h after treatment. Histological analysis showed that 5-azacytidine induced strong apoptosis of neural cells. By 60 h, apoptotic cells disappeared and the tissue was repaired, although the telencephalic wall remained thinner than in controls. Flow cytometry analysis showed that the cell cycle distribution also returned to control levels at 60 h, suggesting that the repair process was completed around 60 h. During the repair period, amoeboid microglia infiltrated the brain and ingested the apoptotic cells. These microglial cells were positive for the multiple microglial markers, and mRNAs for the microglia-related cytokines tumor necrosis factor alpha, interleukin 1beta and macrophage colony stimulating factor (M-CSF) were up-regulated. DNA microarray analysis showed the up-regulation of genes relevant to glial cells, inflammation, the extracellular matrix, glycolysis, proliferation and neural development. We show here that the developing brain has the capacity to respond to the damage induced by extrinsic chemical stresses, including changing the expression of numerous genes and the induction of microglia to aid the repair process.
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Affiliation(s)
- Masaki Ueno
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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34
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Abstract
The signals that lead to the initiation of parturition have remained a mystery. We postulate that in humans and other mammals, uterine quiescence is maintained by increased progesterone receptor (PR) transcriptional activity, and spontaneous labor is initiated or facilitated by a concerted series of biochemical events that negatively impact PR function. In recent studies, we have obtained compelling evidence to suggest that the fetus signals the initiation of labor by secretion into amniotic fluid of major lung surfactant protein, SP-A. SP-A expression is developmentally regulated in fetal lung and is secreted into amniotic fluid in high concentrations near term (after 17 days postcoitum [dpc] in the mouse). We found that injection of exogenous SP-A into mouse amniotic fluid at 15 dpc caused preterm labor. SP-A activated amniotic fluid macrophages in vitro to express nuclear factor kappaB (NF-kappaB) and interleukin-1beta (IL-1beta). These macrophages, which are of fetal origin, migrate to the pregnant uterus causing an inflammatory response and increased uterine NF-kappaB activity. We suggest that the increase in NF-kappaB within the maternal uterus both directly increases expression of genes that promote uterine contractility and negatively impacts the capacity of the PR to maintain uterine quiescence, contributing to the onset of labor. Our findings, therefore, indicate that SP-A secreted into amniotic fluid by the maturing fetal lung serves as a hormone of parturition.
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Affiliation(s)
- Carole R Mendelson
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
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35
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Rezaie P, Dean A, Male D, Ulfig N. Microglia in the cerebral wall of the human telencephalon at second trimester. ACTA ACUST UNITED AC 2004; 15:938-49. [PMID: 15483047 DOI: 10.1093/cercor/bhh194] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have recently begun to gain a clearer understanding of the phasing and patterns of colonization of the developing human brain by microglia. In this study we investigated the distribution, morphology and phenotype of microglia specifically within the wall of the human telencephalon from 12 to 24 gestational weeks (gw), a period that corresponds to the development of thalamocortical fibres passing through the transient subplate region of the developing cerebral wall. Sections from a total of 45 human fetal brains were immunoreacted to detect CD68 and MHC class II antigens and histochemically reacted with RCA-1 and tomato lectins. These markers were differentially expressed by anatomically discrete populations of microglia in the cerebral wall: two cell populations were noted during the initial phase of colonization (12-14 gw): (i) CD68++ RCA-1+ MHC II- amoeboid cells aligned within the subplate, and (ii) RCA-1++ CD68- MHC II- progenitors in the marginal layer and lower cortical plate that progressively ramified within the subplate, without seemingly passing through an 'amoeboid' state. At this stage microglia were largely absent from the germinal layers and the intermediate zone. From 14 to 15 gw, however, MHC class II positive cells were also detected within germinal layers and in the corpus callosum, and these cells, which coexpressed CD68 antigen (a marker associated with phagocytosis), further populated the lower half of the telencephalon from 18 to 24 gw. These findings are discussed in relation to developmental events that take place during the second trimester within the wall of the telencephalon.
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Affiliation(s)
- Payam Rezaie
- Department of Biological Sciences, Faculty of Science, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
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Lian Q, Dheen ST, Liao D, Tay SSW. Enhanced inflammatory response in neural tubes of embryos derived from diabetic mice exposed to a teratogen. J Neurosci Res 2004; 75:554-64. [PMID: 14743439 DOI: 10.1002/jnr.20006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Exposure of embryos to the teratogen cyclophosphamide (CP) and maternal diabetes is linked to pathogenesis of neural tube defects during development. Maternal diabetes aggravates the teratogen-induced inflammatory reaction leading to increased risk of neural tube defects in mouse embryos. The inflammatory reaction in the developing neural tube has been characterized by the presence of activated amoeboid microglia/brain macrophages and altered expression levels of cytokines. Although there were no obvious anomalies observed in the neural tubes of embryos from CP-treated non-diabetic mice, the frequency of neural tube defects was increased significantly in embryos of CP-treated diabetic mice. Moreover, there were more activated amoeboid microglia in the forebrain of CP-treated diabetic embryos compared to that in CP-treated non-diabetic mice. The expression of cytokines such as tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in the fetal brain of normal and diabetic embryos was induced in the neural tubes after CP treatment. Furthermore, the mRNA expression levels of both genes were increased markedly in the neural tube of CP-treated diabetic embryos compared to that of CP-treated non-diabetic embryos as measured by quantitative real-time PCR. Immunohistochemically, more TNF-alpha- and TGF-beta1-positive cells, which included neurons and amoeboid microglia, were detected in CP-treated diabetic embryos than in CP-treated normal embryos. Maternal diabetes aggravates teratogen-induced inflammation, which is characterized in the developing neural tube by increased amoeboid microglia and enhanced expression of inflammatory cytokines. Although a definite link has yet to be elucidated, it is suggested that the increased rate of neural tube defects observed in CP-treated diabetic embryos may be due to upregulation of proinflammatory cytokines caused by maternal diabetes.
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Affiliation(s)
- Qizhou Lian
- Molecular Neurobiology Laboratory, Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore
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Aarum J, Sandberg K, Haeberlein SLB, Persson MAA. Migration and differentiation of neural precursor cells can be directed by microglia. Proc Natl Acad Sci U S A 2003; 100:15983-8. [PMID: 14668448 PMCID: PMC307679 DOI: 10.1073/pnas.2237050100] [Citation(s) in RCA: 337] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2003] [Indexed: 11/18/2022] Open
Abstract
Recent reports have supported the existence of neural stem cells in the adult mammalian CNS. Important features of such cells are self-renewal and multipotency, i.e., they can give rise to neurons, astrocytes, and oligodendrocytes and thus in principle replace lost cells in the CNS. Observations in several animal models of CNS diseases have shown that by unknown mechanisms endogenous as well as exogenous precursor cells preferentially migrate to damaged areas. Microglia are immunoreactive cells of nonneural lineage resident in the CNS. After injury to the CNS, microglia are rapidly activated and found concentrated at the sites of injury. In the present article we show, in two different assays, that soluble factors released from mouse microglial cells direct the migration of neural CNS precursor cells. We also provide evidence that microglia have the capacity to influence the differentiation of both adult and embryonic neural precursor cells toward a neuronal phenotype. Given that an invariant feature of pathological processes in CNS is the activation of microglia, these results indicate an important and unique role for microglia in directing the replacement of damaged or lost cells in the CNS.
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Affiliation(s)
- Johan Aarum
- Karolinska Institutet, Department of Medicine and Center for Molecular Medicine, Karolinska Hospital, 171 76 Stockholm, Sweden
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Dalmau I, Vela JM, González B, Finsen B, Castellano B. Dynamics of microglia in the developing rat brain. J Comp Neurol 2003; 458:144-57. [PMID: 12596255 DOI: 10.1002/cne.10572] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Entrance of mesodermal precursors into the developing CNS is the most well-accepted origin of microglia. However, the contribution of proliferation and death of recruited microglial precursors to the final microglial cell population remains to be elucidated. To investigate microglial proliferation and apoptosis during development, we combined proliferating cell nuclear antigen (PCNA) immunohistochemistry, in situ detection of nuclear DNA fragmentation (TUNEL), and caspase-3 immunohistochemistry with tomato lectin histochemistry, a selective microglial marker. The study was carried out in Wistar rats from embryonic day (E) 16 to postnatal day (P) 18 in cerebral cortex, subcortical white matter, and hippocampus. Proliferating microglial cells were found at all ages in the three brain regions and represented a significant fraction of the total microglial cell population. The percentage of microglia expressing PCNA progressively increased from the embryonic period (25-51% at E16) to a maximum at P9, when the great majority of microglia expressed PCNA (92-99%) in all the brain regions analyzed. In spite of the remarkable proliferation and expansion of the microglial population with time, the density of microglia remained quite constant in most brain regions because of the considerable growth of the brain during late prenatal and early postnatal periods. In contrast, apoptosis of microglia was detected only at certain times and was restricted to some ameboid cells in white matter and primitive ramified cells in gray matter, representing a small fraction of the microglial population. Therefore, our results point to proliferation of microglial precursors in the developing brain as a physiological mechanism contributing to the acquisition of the adult microglial cell population. In contrast, microglial apoptosis occurs only locally at certain developmental stages and thus seems less crucial for the establishment of the final density of microglia.
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Affiliation(s)
- Ishar Dalmau
- Departmet of Histology, Faculty of Medicine, Autonomous University of Barcelona, E-08193-Bellaterra, Spain
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Wang CC, Wu CH, Shieh JY, Wen CY. Microglial distribution and apoptosis in fetal rat brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 139:337-42. [PMID: 12480151 DOI: 10.1016/s0165-3806(02)00584-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
By histochemical and immunocytochemical techniques, this study aimed to determine the possible involvement of apoptosis in regulating the microglial distribution in fetal rat brain. While microglial cells were labeled with the isolectin Griffonia simplicifolia (GSA I-B4), apoptotic cells were detected by using terminal transferase-mediated dUTP nick end-labeling (TUNEL). TUNEL-labeled cells occurred mainly in the dorsal midline along its rostral-caudal axis of the brain where lectin-labeled microglia were also observed. Occasional TUNEL-labeled cells were observed in the intermediate zone lateral to the striatum (IZS) where lectin-labeled microglia were common from embryonic day 16 (E16) onwards. Some of lectin-labeled microglia showing different morphological forms ingested TUNEL-labeled bodies. In contrast, lectin-labeled microglia showing signs of apoptosis appeared to be lacking. These results clearly demonstrated that lectin-labeled microglia were distributed in areas with and without the occurrence of a large concentration of TUNEL-labeled cells. Our studies suggest that microglia in fetal rat brain will undergo differentiation and activation rather than apoptotic death to govern their population.
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Affiliation(s)
- Chao Chuan Wang
- Department of Anatomy, College of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, Taiwan.
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Herbomel P, Thisse B, Thisse C. Zebrafish early macrophages colonize cephalic mesenchyme and developing brain, retina, and epidermis through a M-CSF receptor-dependent invasive process. Dev Biol 2001; 238:274-88. [PMID: 11784010 DOI: 10.1006/dbio.2001.0393] [Citation(s) in RCA: 416] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The origin of resident (noninflammatory) macrophages in vertebrate tissues is still poorly understood. In the zebrafish embryo, we recently described a specific lineage of early macrophages that differentiate in the yolk sac before the onset of blood circulation. We now show that these early macrophages spread in the whole cephalic mesenchyme, and from there invade epithelial tissues: epidermis, retina, and brain--especially the optic tectum. In the panther mutant, which lacks a functional fms (M-CSF receptor) gene, early macrophages differentiate and behave apparently normally in the yolk sac, but then fail to invade embryonic tissues. Our video recordings then document for the first time the behavior of macrophages in the invaded tissues, revealing the striking propensity of early macrophages in epidermis and brain to wander restlessly among epithelial cells. This unexpected behavior suggests that tissue macrophages may be constantly "patrolling" for immune and possibly also developmental and trophic surveillance. At 60 h post-fertilization, all macrophages in the brain and retina undergo a specific phenotypic transformation, into "early (amoeboid) microglia": they become more highly endocytic, they down-regulate the L-plastin gene, and abruptly start expressing high levels of apolipoprotein E, a well-known neurotrophic lipid carrier.
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Affiliation(s)
- P Herbomel
- Unité de Génétique des Déficits Sensoriels, URA 1968 du CNRS, Département des Biotechnologies, Institut Pasteur, 25 rue du Dr Roux, Paris Cedex 15, 75724, France.
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Hubeau C, Puchelle E, Gaillard D. Distinct pattern of immune cell population in the lung of human fetuses with cystic fibrosis. J Allergy Clin Immunol 2001; 108:524-9. [PMID: 11590376 DOI: 10.1067/mai.2001.118516] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Airway inflammation and infection are early events in cystic fibrosis (CF) pathogenesis. The existence of an imbalance in the immune cell population of the CF fetal airway before infection remains completely unknown. OBJECTIVE The aim of this study was to determine whether early signs of inflammation are observed in CF airways during human fetal development. METHODS Tracheas and lungs were collected from 21 CF and 16 non-CF fetuses. In tissue sections, the numbers of neutrophils, mast cells, macrophages, and B and T lymphocytes were quantitatively analyzed by means of image cytometry. The presence of IL-4, IL-6, IL-8, IL-10, RANTES, IFN-gamma, TNF-alpha, and NF kappa B and its inhibitor I kappa B-alpha was qualitatively evaluated by immunofluorescent staining. RESULTS During fetal airway development, epithelial and glandular differentiation, as well as the distribution of inflammatory markers, was similar in CF and non-CF tissues. Significant differences between CF and non-CF fetal airways were observed only in the numbers of mast cells and macrophages. In the CF trachea, the mast cell number increased slowly but continuously, whereas in the non-CF trachea this number rapidly reached a plateau. In the CF lung, the macrophage number increased with time, whereas in the non-CF lung it decreased. CONCLUSION Although no intrinsic inflammation was demonstrated, we observed a distinct appearance of mast cells and macrophages in CF airways in comparison with non-CF airways during fetal development. These 2 cell populations were greater in CF airways at a late stage of fetal development, suggesting their possible involvement in the early onset of inflammation in CF infants.
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Affiliation(s)
- C Hubeau
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 514, Institut Fédératif de Recherche (IFR) 53, Université de Reims Champagne-Ardenne, Reims, France
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Abstract
An understanding of microglial functions during normal CNS development is prerequisite for understanding developmental neurotoxicology. This review provides a brief summary of previous work regarding the origin of microglia and addresses differences and similarities between microglia and brain macrophages. Current concepts and ideas which implicate microglia in diverse developmental processes, such as apoptosis, axon growth, and vasculogenesis are discussed. The study of reactive microgliosis may prove useful in the histopathological analysis of neurotoxicant-induced brain damage during development.
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Affiliation(s)
- W J Streit
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute, Gainesville 32611, USA.
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Cuadros MA, Navascués J. Early origin and colonization of the developing central nervous system by microglial precursors. PROGRESS IN BRAIN RESEARCH 2001; 132:51-9. [PMID: 11545016 DOI: 10.1016/s0079-6123(01)32065-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- M A Cuadros
- Departamento de Biología Celular, Facultad de Ciencias, Universidad de Granada, E-18071 Granada, Spain.
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Abstract
The postnatal development of rat microglia is marked by an important increase in the number of microglial cells and the growth of their ramified processes. We studied the role of thyroid hormone in microglial development. The distribution and morphology of microglial cells stained with isolectin B4 or monoclonal antibody ED1 were analyzed in cortical and subcortical forebrain regions of developing rats rendered hypothyroid by prenatal and postnatal treatment with methyl-thiouracil. Microglial processes were markedly less abundant in hypothyroid pups than in age-matched normal animals, from postnatal day 4 up to the end of the third postnatal week of life. A delay in process extension and a decrease in the density of microglial cell bodies, as shown by cell counts in the developing cingulate cortex of normal and hypothyroid animals, were responsible for these differences. Conversely, neonatal rat hyperthyroidism, induced by daily injections of 3,5,3'-triiodothyronine (T3), accelerated the extension of microglial processes and increased the density of cortical microglial cell bodies above physiological levels during the first postnatal week of life. Reverse transcription-PCR and immunological analyses indicated that cultured cortical ameboid microglial cells expressed the alpha1 and beta1 isoforms of nuclear thyroid hormone receptors. Consistent with the trophic and morphogenetic effects of thyroid hormone observed in situ, T3 favored the survival of cultured purified microglial cells and the growth of their processes. These results demonstrate that thyroid hormone promotes the growth and morphological differentiation of microglia during development.
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Hao AJ, Dheen ST, Ling EA. Response of amoeboid microglia/brain macrophages in fetal rat brain exposed to a teratogen. J Neurosci Res 2001; 64:79-93. [PMID: 11276054 DOI: 10.1002/jnr.1056] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study examined the time course response of amoeboid microglia/brain macrophages in the rat fetus induced by a single intraperitoneal injection of cyclophosphamide, a teratogen, into the mother rat at 13 days of gestation. Compared to the normal fetal brain, a marked increase in amoeboid microglia was observed in the telencephalon and diencephalon of experimental fetuses, especially in those killed at embryonic day 15. Conglomerations of microglia occurred in the dorsal and superior neuroepithelium of diencephalon, basal telencephalon, cortical neuroepithelium, and hippocampal formation as identified with OX-42, OX-18, and ED-1 by immunohistochemistry. Rhodamine isothiocynate (RhIc) as a tracer was injected via the tail vein into the pregnant rat to assess the phagocytic capability of these cells. Following the tracer injection, none of microglial cells in normal fetal brain was detectable. RhIc, however, was readily taken up by amoeboid microglia in fetal brain with injury insult. Double labeling has shown that the RhIc-labeled cells were immunoreactive with ED-1, OX-42, OX-18, and OX-6, confirming their microglial nature. Microglial proliferation was assessed by immunohistochemistry using bromodeoxyuridine, which showed a marked increase in mitotic activity. Confocal microscopic analysis revealed that a varying number of microglia coexpressed iNOS, macrophage colony-stimulating factor (M-CSF), and ICAM-1. RT-PCR analysis showed increased expression of M-CSF mRNA. Furthermore, colony-stimulating factor-1 receptor mRNA was localized in microglia by in situ hybridization. The present results suggest that NO along with M-CSF and ICAM-1 is involved in microglial proliferation in prenatal brain injury.
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Affiliation(s)
- A J Hao
- Molecular Neurobiology Laboratory, Department of Anatomy, Faculty of Medicine, National University of Singapore, Republic of Singapore 117597
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Calvo CF, Cesselin F, Gelman M, Glowinski J. Identification of an opioid peptide secreted by rat embryonic mixed brain cells as a promoter of macrophage migration. Eur J Neurosci 2000; 12:2676-84. [PMID: 10971611 DOI: 10.1046/j.1460-9568.2000.00145.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Conditioned media from embryonic mixed cells from the rat brain were used in a chemotaxis assay to look for potential chemotactic activity which could account for the infiltration of the developing central nervous system (CNS) by macrophage precursors. The most potent chemotactic activity was found in the conditioned medium from E17 mixed brain cells (E17-CM). Based upon checkerboard analysis, this activity was shown to be chemotactic rather than chemokinetic. This chemoattraction was not restricted to brain macrophages (BM) because it was as pronounced on bone marrow-derived macrophages. The implication of a peptide compound in this activity was suggested by its resistance to heat as well as acid treatments, and by its sensitivity to aminopeptidase M digestion. In agreement with the opioid nature of the peptide, not only naloxone, but also the delta opioid receptor antagonist ICI-174 reduced the migration of BM in response to E17-CM by 60%. This migratory activity was no longer effective when pertussis toxin-treated BM were used. When the chemotactic effects of selective opioid agonists were compared to that of E17-CM, DPDPE, the delta agonist, was the most efficient in attracting BM. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis indicated that delta as well as other known opioid receptors were expressed in both BM and E17 mixed brain cells. Finally, a Met-enkephalin-like reactivity was found by RIA in the E17-CM. Altogether, these observations suggest that a delta-like opioid peptide released from embryonic mixed brain cells could be responsible for the infiltration of the developing CNS by macrophages precursors.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Brain/cytology
- Brain/embryology
- Cells, Cultured
- Chemotaxis, Leukocyte/drug effects
- Chemotaxis, Leukocyte/physiology
- Culture Media, Conditioned/pharmacology
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Gene Expression Regulation, Developmental
- Macrophages/cytology
- Microglia/cytology
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Oligonucleotide Probes
- Oligopeptides/pharmacology
- Opioid Peptides/analysis
- Opioid Peptides/metabolism
- RNA, Messenger/analysis
- Rats
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/genetics
- Stem Cells/cytology
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Affiliation(s)
- C F Calvo
- Chaire de Neuropharmacologie, INSERM U114, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris CEDEX 05, France.
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48
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Abstract
To review the data on the origins, phenotype, and function of embryonic phagocytes that has accumulated over past decade. Most of the relevant articles were selected based on the PubMed database entries. In additional, the Interactive Fly database (http://sdb.bio. purdue.edu/fly/aimain/1aahome.htm), FlyBase (http://flybase.bio. indiana.edu:82/), and TBase (http://tbase.jax.org/) were used to search for relevant information and articles. Phagocytes in a vertebrate embryo develop in two sites (yolk sac and liver) and contribute to organogenesis in part through their ability to recognize and clear apoptotic cells. Yolk sac-derived phagocytes differ in differentiation pathway and marker gene expression from macrophages produced via classic hematopoietic progenitors in the liver. We argue that yolk sac-derived phagocytes constitute a separate cell lineage. This conclusion raises the question of whether primitive phagocytes persist into the adulthood.
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Affiliation(s)
- A M Lichanska
- Departments of Medical Genetics and Ophthalmology, Queen's University of Belfast, Belfast, United Kingdom
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Alliot F, Godin I, Pessac B. Microglia derive from progenitors, originating from the yolk sac, and which proliferate in the brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1999; 117:145-52. [PMID: 10567732 DOI: 10.1016/s0165-3806(99)00113-3] [Citation(s) in RCA: 581] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Microglia, the resident CNS macrophages, represent about 10% of the adult brain cell population. Although described a long time ago, their origin and developmental lineage is still debated. While del Rio-Hortega suggested that microglia originate from meningeal macrophages penetrating the brain during embryonic development, many authors claim that brain parenchymal microglia derive from circulating blood monocytes originating from bone marrow. We have previously reported that the late embryonic and adult mouse brain parenchyma contains potential microglial progenitors [F. Alliot, E. Lecain, B. Grima, B. Pessac, Microglial progenitors with a high proliferative capacity in the embryonic and the adult mouse brain, Proc. Natl. Acad. Sci. U.S.A. 88 (1991) 1541-1545]. We now report that they can be detected in the brain rudiment from embryonic day 8, after their appearance in the yolk sac and that their number increases until late gestation. We also show that microglia appear during embryonic development and that their number increases steadily during the first two postnatal weeks, when about 95% of microglia are born. Finally, the main finding of this study is that microglia is the result of in situ proliferation, as shown by the high proportion of parenchymal microglial cells that express PCNA, a marker of cell multiplication, in embryonic and postnatal brain. Taken together, our data support the hypothesis that terminally differentiated brain parenchymal microglia are derived from cells originating from the yolk sac whose progeny actively proliferates in situ during development.
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Affiliation(s)
- F Alliot
- UPR CNRS 9035 "Développement et Immunité du Système Nerveux Central" 15 rue de l'Ecole de Médecine, 75270, Paris, France
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Ono K, Takii T, Onozaki K, Ikawa M, Okabe M, Sawada M. Migration of exogenous immature hematopoietic cells into adult mouse brain parenchyma under GFP-expressing bone marrow chimera. Biochem Biophys Res Commun 1999; 262:610-4. [PMID: 10471372 DOI: 10.1006/bbrc.1999.1223] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bone marrow transplantation with GFP-expressing cells from GFP-transgenic mice resulted in migration of GFP-positive cells into peripheral tissues and brain parenchyma. Most of these cells were observed as colony-like clusters. GFP-positive clusters in the brain were stained by antibody for ER-MP12, but those in the peripheral tissues were not. Since ER-MP12 antigen has been reported as a marker for murine early-stage myeloid precursor, this might suggest that some parts of phagocytic cells in the brain parenchyma such as microglia are derived from undifferentiated pluripotent hematopoietic cells.
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Affiliation(s)
- K Ono
- Faculty of Pharmaceutical Sciences, Nagoya City University, Mizuho, Nagoya, Aichi, 467-8603, Japan
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