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Barry-Carroll L, Gomez-Nicola D. The molecular determinants of microglial developmental dynamics. Nat Rev Neurosci 2024; 25:414-427. [PMID: 38658739 DOI: 10.1038/s41583-024-00813-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2024] [Indexed: 04/26/2024]
Abstract
Microglia constitute the largest population of parenchymal macrophages in the brain and are considered a unique subset of central nervous system glial cells owing to their extra-embryonic origins in the yolk sac. During development, microglial progenitors readily proliferate and eventually colonize the entire brain. In this Review, we highlight the origins of microglial progenitors and their entry routes into the brain and discuss the various molecular and non-molecular determinants of their fate, which may inform their specific functions. Specifically, we explore recently identified mechanisms that regulate microglial colonization of the brain, including the availability of space, and describe how the expansion of highly proliferative microglial progenitors facilitates the occupation of the microglial niche. Finally, we shed light on the factors involved in establishing microglial identity in the brain.
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Affiliation(s)
- Liam Barry-Carroll
- Nutrineuro, UMR 1286 INRAE, Bordeaux University, Bordeaux INP, Bordeaux, France
| | - Diego Gomez-Nicola
- School of Biological Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
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2
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Fu YW, Jin SY, Li JT, Li XW, Gao TM, Yang JM. Mature astrocytes as source for astrocyte repopulation after deletion in the medial prefrontal cortex: Implications for depression. Glia 2024. [PMID: 38801194 DOI: 10.1002/glia.24573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/31/2024] [Accepted: 05/13/2024] [Indexed: 05/29/2024]
Abstract
The adult brain retains a high repopulation capacity of astrocytes after deletion, and both mature astrocytes in the neocortex and neural stem cells in neurogenic regions possess the potential to generate astrocytes. However, the origin and the repopulation dynamics of the repopulating astrocytes after deletion remain largely unclear. The number of astrocytes is reduced in the medial prefrontal cortex (mPFC) of patients with depression, and selective elimination of mPFC astrocytes is sufficient to induce depression-like behaviors in rodents. However, whether astrocyte repopulation capacity is impaired in depression is unknown. In this study, we used different transgenic mouse lines to genetically label different cell types and demonstrated that in the mPFC of normal adult mice of both sexes, mature astrocytes were a major source of the repopulating astrocytes after acute deletion induced by an astrocyte-specific toxin, L-alpha-aminoadipic acid (L-AAA), and astrocyte regeneration was accomplished within two weeks accompanied by reversal of depression-like behaviors. Furthermore, re-ablation of mPFC astrocytes post repopulation led to reappearance of depression-like behaviors. In adult male mice subjected to 14-day chronic restraint stress, a well-validated mouse model of depression, the number of mPFC astrocytes was reduced; however, the ability of mPFC astrocytes to repopulate after L-AAA-induced deletion was largely unaltered. Our study highlights a potentially beneficial role for repopulating astrocytes in depression and provides novel therapeutic insights into enhancing local mature astrocyte generation in depression.
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Affiliation(s)
- Yi-Wen Fu
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Shi-Yang Jin
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jing-Ting Li
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Xiao-Wen Li
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Tian-Ming Gao
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- State Key Laboratory of Organ Failure Research, Southern Medical University, Guangzhou, China
| | - Jian-Ming Yang
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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3
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Surala M, Soso-Zdravkovic L, Munro D, Rifat A, Ouk K, Vida I, Priller J, Madry C. Lifelong absence of microglia alters hippocampal glutamatergic networks but not synapse and spine density. EMBO Rep 2024; 25:2348-2374. [PMID: 38589666 PMCID: PMC11094096 DOI: 10.1038/s44319-024-00130-9] [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: 02/27/2024] [Revised: 03/13/2024] [Accepted: 03/20/2024] [Indexed: 04/10/2024] Open
Abstract
Microglia sculpt developing neural circuits by eliminating excess synapses in a process called synaptic pruning, by removing apoptotic neurons, and by promoting neuronal survival. To elucidate the role of microglia during embryonic and postnatal brain development, we used a mouse model deficient in microglia throughout life by deletion of the fms-intronic regulatory element (FIRE) in the Csf1r locus. Surprisingly, young adult Csf1rΔFIRE/ΔFIRE mice display no changes in excitatory and inhibitory synapse number and spine density of CA1 hippocampal neurons compared with Csf1r+/+ littermates. However, CA1 neurons are less excitable, receive less CA3 excitatory input and show altered synaptic properties, but this does not affect novel object recognition. Cytokine profiling indicates an anti-inflammatory state along with increases in ApoE levels and reactive astrocytes containing synaptic markers in Csf1rΔFIRE/ΔFIRE mice. Notably, these changes in Csf1rΔFIRE/ΔFIRE mice closely resemble the effects of acute microglial depletion in adult mice after normal development. Our findings suggest that microglia are not mandatory for synaptic pruning, and that in their absence pruning can be achieved by other mechanisms.
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Affiliation(s)
- Michael Surala
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany
| | - Luna Soso-Zdravkovic
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany
| | - David Munro
- University of Edinburgh and UK Dementia Research Institute, Edinburgh, EH16 4TJ, UK
| | - Ali Rifat
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Koliane Ouk
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Neuropsychiatry and Laboratory of Molecular Psychiatry, Charitéplatz 1, 10117, Berlin, Germany
| | - Imre Vida
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute for Integrative Neuroanatomy, Charitéplatz 1, 10117, Berlin, Germany
| | - Josef Priller
- University of Edinburgh and UK Dementia Research Institute, Edinburgh, EH16 4TJ, UK.
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Neuropsychiatry and Laboratory of Molecular Psychiatry, Charitéplatz 1, 10117, Berlin, Germany.
- DZNE Berlin, 10117, Berlin, Germany.
- Department of Psychiatry and Psychotherapy; School of Medicine and Health, Technical University of Munich and German Center for Mental Health (DZPG), 81675, Munich, Germany.
| | - Christian Madry
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Institute of Neurophysiology, Charitéplatz 1, 10117, Berlin, Germany.
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4
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Verkerke M, Berdenis van Berlekom A, Donega V, Vonk D, Sluijs JA, Butt NF, Kistemaker L, de Witte LD, Pasterkamp RJ, Middeldorp J, Hol EM. Transcriptomic and morphological maturation of human astrocytes in cerebral organoids. Glia 2024; 72:362-374. [PMID: 37846809 DOI: 10.1002/glia.24479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 09/28/2023] [Accepted: 10/02/2023] [Indexed: 10/18/2023]
Abstract
Cerebral organoids (CerOrgs) derived from human induced pluripotent stem cells (iPSCs) are a valuable tool to study human astrocytes and their interaction with neurons and microglia. The timeline of astrocyte development and maturation in this model is currently unknown and this limits the value and applicability of the model. Therefore, we generated CerOrgs from three healthy individuals and assessed astrocyte maturation after 5, 11, 19, and 37 weeks in culture. At these four time points, the astrocyte lineage was isolated based on the expression of integrin subunit alpha 6 (ITGA6). Based on the transcriptome of the isolated ITGA6-positive cells, astrocyte development started between 5 and 11 weeks in culture and astrocyte maturation commenced after 11 weeks in culture. After 19 weeks in culture, the ITGA6-positive astrocytes had the highest expression of human mature astrocyte genes, and the predicted functional properties were related to brain homeostasis. After 37 weeks in culture, a subpopulation of ITGA6-negative astrocytes appeared, highlighting the heterogeneity within the astrocytes. The morphology shifted from an elongated progenitor-like morphology to the typical bushy astrocyte morphology. Based on the morphological properties, predicted functional properties, and the similarities with the human mature astrocyte transcriptome, we concluded that ITGA6-positive astrocytes have developed optimally in 19-week-old CerOrgs.
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Affiliation(s)
- Marloes Verkerke
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Amber Berdenis van Berlekom
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Psychiatry, University Medical Center Utrecht, Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Vanessa Donega
- Amsterdam UMC location Vrije Universiteit Amsterdam, Anatomy & Neurosciences, section Clinical Neuroanatomy and Biobanking, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Cellular and Molecular Mechanisms, Amsterdam, The Netherlands
| | - Daniëlle Vonk
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Jacqueline A Sluijs
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Nayab F Butt
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Lois Kistemaker
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Lot D de Witte
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Jinte Middeldorp
- Department of Neurobiology & Aging, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Elly M Hol
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
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Luo Y, Wang Z. The Impact of Microglia on Neurodevelopment and Brain Function in Autism. Biomedicines 2024; 12:210. [PMID: 38255315 PMCID: PMC10813633 DOI: 10.3390/biomedicines12010210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/29/2023] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Microglia, as one of the main types of glial cells in the central nervous system (CNS), are widely distributed throughout the brain and spinal cord. The normal number and function of microglia are very important for maintaining homeostasis in the CNS. In recent years, scientists have paid widespread attention to the role of microglia in the CNS. Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder, and patients with ASD have severe deficits in behavior, social skills, and communication. Most previous studies on ASD have focused on neuronal pathological changes, such as increased cell proliferation, accelerated neuronal differentiation, impaired synaptic development, and reduced neuronal spontaneous and synchronous activity. Currently, more and more research has found that microglia, as immune cells, can promote neurogenesis and synaptic pruning to maintain CNS homeostasis. They can usually reduce unnecessary synaptic connections early in life. Some researchers have proposed that many pathological phenotypes of ASD may be caused by microglial abnormalities. Based on this, we summarize recent research on microglia in ASD, focusing on the function of microglia and neurodevelopmental abnormalities. We aim to clarify the essential factors influenced by microglia in ASD and explore the possibility of microglia-related pathways as potential research targets for ASD.
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Affiliation(s)
- Yuyi Luo
- State Key Laboratory of Primate Biomedical Research, Institute of Primate Translational Medicine, Kunming University of Science and Technology, Kunming 650500, China;
- Yunnan Key Laboratory of Primate Biomedical Research, Kunming 650500, China
| | - Zhengbo Wang
- State Key Laboratory of Primate Biomedical Research, Institute of Primate Translational Medicine, Kunming University of Science and Technology, Kunming 650500, China;
- Yunnan Key Laboratory of Primate Biomedical Research, Kunming 650500, China
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6
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Xu P, Yu Y, Wu P. Role of microglia in brain development after viral infection. Front Cell Dev Biol 2024; 12:1340308. [PMID: 38298216 PMCID: PMC10825034 DOI: 10.3389/fcell.2024.1340308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 01/04/2024] [Indexed: 02/02/2024] Open
Abstract
Microglia are immune cells in the brain that originate from the yolk sac and enter the developing brain before birth. They play critical roles in brain development by supporting neural precursor proliferation, synaptic pruning, and circuit formation. However, microglia are also vulnerable to environmental factors, such as infection and stress that may alter their phenotype and function. Viral infection activates microglia to produce inflammatory cytokines and anti-viral responses that protect the brain from damage. However, excessive or prolonged microglial activation impairs brain development and leads to long-term consequences such as autism spectrum disorder and schizophrenia spectrum disorder. Moreover, certain viruses may attack microglia and deploy them as "Trojan horses" to infiltrate the brain. In this brief review, we describe the function of microglia during brain development and examine their roles after infection through microglia-neural crosstalk. We also identify limitations for current studies and highlight future investigated questions.
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Affiliation(s)
- Pei Xu
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX, United States
| | - Yongjia Yu
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, TX, United States
| | - Ping Wu
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX, United States
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7
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Tewari M, Michalski S, Egan TM. Modulation of Microglial Function by ATP-Gated P2X7 Receptors: Studies in Rat, Mice and Human. Cells 2024; 13:161. [PMID: 38247852 PMCID: PMC10814008 DOI: 10.3390/cells13020161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 01/23/2024] Open
Abstract
P2X receptors are a family of seven ATP-gated ion channels that trigger physiological and pathophysiological responses in a variety of cells. Five of the family members are sensitive to low concentrations of extracellular ATP, while the P2X6 receptor has an unknown affinity. The last subtype, the P2X7 receptor, is unique in requiring millimolar concentrations to fully activate in humans. This low sensitivity imparts the agonist with the ability to act as a damage-associated molecular pattern that triggers the innate immune response in response to the elevated levels of extracellular ATP that accompany inflammation and tissue damage. In this review, we focus on microglia because they are the primary immune cells of the central nervous system, and they activate in response to ATP or its synthetic analog, BzATP. We start by introducing purinergic receptors and then briefly consider the roles that microglia play in neurodevelopment and disease by referencing both original works and relevant reviews. Next, we move to the role of extracellular ATP and P2X receptors in initiating and/or modulating innate immunity in the central nervous system. While most of the data that we review involve work on mice and rats, we highlight human studies of P2X7R whenever possible.
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8
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Fan G, Ma J, Ma R, Suo M, Chen Y, Zhang S, Zeng Y, Chen Y. Microglia Modulate Neurodevelopment in Autism Spectrum Disorder and Schizophrenia. Int J Mol Sci 2023; 24:17297. [PMID: 38139124 PMCID: PMC10743577 DOI: 10.3390/ijms242417297] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
Neurodevelopmental disorders (NDDs) include various neurological disorders with high genetic heterogeneity, characterized by delayed or impaired cognition, communication, adaptive behavior, and psychomotor skills. These disorders result in significant morbidity for children, thus burdening families and healthcare/educational systems. However, there is a lack of early diagnosis and effective therapies. Therefore, a more connected approach is required to explore these disorders. Microglia, the primary phagocytic cells within the central nervous system, are crucial in regulating neuronal viability, influencing synaptic dynamics, and determining neurodevelopmental outcomes. Although the neurobiological basis of autism spectrum disorder (ASD) and schizophrenia (SZ) has attracted attention in recent decades, the role of microglia in ASD and SZ remains unclear and requires further discussion. In this review, the important and frequently multifaceted roles that microglia play during neurodevelopment are meticulously emphasized and potential microglial mechanisms that might be involved in conditions such as ASD and SZ are postulated. It is of utmost importance to acquire a comprehensive understanding of the complexities of the interplay between microglia and neurons to design effective, targeted therapeutic strategies to mitigate the effects of NDDs.
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Affiliation(s)
| | | | | | | | | | | | - Yan Zeng
- Brain Science and Advanced Technology Institute, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan 430065, China
| | - Yushan Chen
- Brain Science and Advanced Technology Institute, Hubei Province Key Laboratory of Occupational Hazard Identification and Control, School of Medicine, Wuhan University of Science and Technology, Wuhan 430065, China
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Matuleviciute R, Akinluyi ET, Muntslag TAO, Dewing JM, Long KR, Vernon AC, Tremblay ME, Menassa DA. Microglial contribution to the pathology of neurodevelopmental disorders in humans. Acta Neuropathol 2023; 146:663-683. [PMID: 37656188 PMCID: PMC10564830 DOI: 10.1007/s00401-023-02629-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 09/02/2023]
Abstract
Microglia are the brain's resident macrophages, which guide various developmental processes crucial for brain maturation, activity, and plasticity. Microglial progenitors enter the telencephalic wall by the 4th postconceptional week and colonise the fetal brain in a manner that spatiotemporally tracks key neurodevelopmental processes in humans. However, much of what we know about how microglia shape neurodevelopment comes from rodent studies. Multiple differences exist between human and rodent microglia warranting further focus on the human condition, particularly as microglia are emerging as critically involved in the pathological signature of various cognitive and neurodevelopmental disorders. In this article, we review the evidence supporting microglial involvement in basic neurodevelopmental processes by focusing on the human species. We next concur on the neuropathological evidence demonstrating whether and how microglia contribute to the aetiology of two neurodevelopmental disorders: autism spectrum conditions and schizophrenia. Next, we highlight how recent technologies have revolutionised our understanding of microglial biology with a focus on how these tools can help us elucidate at unprecedented resolution the links between microglia and neurodevelopmental disorders. We conclude by reviewing which current treatment approaches have shown most promise towards targeting microglia in neurodevelopmental disorders and suggest novel avenues for future consideration.
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Affiliation(s)
- Rugile Matuleviciute
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Elizabeth T Akinluyi
- Division of Medical Sciences, University of Victoria, Victoria, Canada
- Department of Pharmacology and Therapeutics, Afe Babalola University, Ado Ekiti, Nigeria
| | - Tim A O Muntslag
- Princess Maxima Centre for Paediatric Oncology, Utrecht, The Netherlands
| | | | - Katherine R Long
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Anthony C Vernon
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | | | - David A Menassa
- Department of Neuropathology & The Queen's College, University of Oxford, Oxford, UK.
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.
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Sun M, You H, Hu X, Luo Y, Zhang Z, Song Y, An J, Lu H. Microglia-Astrocyte Interaction in Neural Development and Neural Pathogenesis. Cells 2023; 12:1942. [PMID: 37566021 PMCID: PMC10417796 DOI: 10.3390/cells12151942] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/22/2023] [Accepted: 07/24/2023] [Indexed: 08/12/2023] Open
Abstract
The interaction between microglia and astrocytes exhibits a relatively balanced state in order to maintain homeostasis in the healthy central nervous system (CNS). Disease stimuli alter microglia-astrocyte interaction patterns and elicit cell-type-specific responses, resulting in their contribution to various pathological processes. Here, we review the similarities and differences in the activation modes between microglia and astrocytes in various scenarios, encompassing different stages of neural development and a wide range of neural disorders. The aim is to provide a comprehensive understanding of their roles in neural development and regeneration and guiding new strategies for restoring CNS homeostasis.
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Affiliation(s)
- Meiqi Sun
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
| | - Hongli You
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
| | - Xiaoxuan Hu
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
- Department of Human Anatomy & Histoembryology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Yujia Luo
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
| | - Zixuan Zhang
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
- Department of Human Anatomy & Histoembryology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Yiqun Song
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
| | - Jing An
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
| | - Haixia Lu
- Department/Institute of Neurobiology, School of Basic Medical Science, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China; (M.S.); (H.Y.); (X.H.); (Y.L.); (Z.Z.); (Y.S.)
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11
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Hattori Y. The multifaceted roles of embryonic microglia in the developing brain. Front Cell Neurosci 2023; 17:988952. [PMID: 37252188 PMCID: PMC10213237 DOI: 10.3389/fncel.2023.988952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 04/03/2023] [Indexed: 05/31/2023] Open
Abstract
Microglia are the resident immune cells of the central nervous system (CNS). Microglia originate from erythromyeloid progenitors in the yolk sac at the early embryonic stage, and these progenitors then colonize the CNS through extensive migration and proliferation during development. Microglia account for 10% of all cells in the adult brain, whereas the proportion of these cells in the embryonic brain is only 0.5-1.0%. Nevertheless, microglia in the developing brain widely move their cell body within the structure by extending filopodia; thus, they can interact with surrounding cells, such as neural lineage cells and vascular-structure-composing cells. This active microglial motility suggests that embryonic microglia play a pivotal role in brain development. Indeed, recent increasing evidence has revealed diverse microglial functions at the embryonic stage. For example, microglia control differentiation of neural stem cells, regulate the population size of neural progenitors and modulate the positioning and function of neurons. Moreover, microglia exert functions not only on neural lineage cells but also on blood vessels, such as supporting vascular formation and integrity. This review summarizes recent advances in the understanding of microglial cellular dynamics and multifaceted functions in the developing brain, with particular focus on the embryonic stage, and discusses the fundamental molecular mechanisms underlying their behavior.
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12
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Otero AM, Antonson AM. At the crux of maternal immune activation: Viruses, microglia, microbes, and IL-17A. Immunol Rev 2022; 311:205-223. [PMID: 35979731 PMCID: PMC9804202 DOI: 10.1111/imr.13125] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Inflammation during prenatal development can be detrimental to neurodevelopmental processes, increasing the risk of neuropsychiatric disorders. Prenatal exposure to maternal viral infection during pregnancy is a leading environmental risk factor for manifestation of these disorders. Preclinical animal models of maternal immune activation (MIA), established to investigate this link, have revealed common immune and microbial signaling pathways that link mother and fetus and set the tone for prenatal neurodevelopment. In particular, maternal intestinal T helper 17 cells, educated by endogenous microbes, appear to be key drivers of effector IL-17A signals capable of reaching the fetal brain and causing neuropathologies. Fetal microglial cells are particularly sensitive to maternally derived inflammatory and microbial signals, and they shift their functional phenotype in response to MIA. Resulting cortical malformations and miswired interneuron circuits cause aberrant offspring behaviors that recapitulate core symptoms of human neurodevelopmental disorders. Still, the popular use of "sterile" immunostimulants to initiate MIA has limited translation to the clinic, as these stimulants fail to capture biologically relevant innate and adaptive inflammatory sequelae induced by live pathogen infection. Thus, there is a need for more translatable MIA models, with a focus on relevant pathogens like seasonal influenza viruses.
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Affiliation(s)
- Ashley M. Otero
- Neuroscience ProgramUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
| | - Adrienne M. Antonson
- Department of Animal SciencesUniversity of Illinois Urbana‐ChampaignUrbanaIllinoisUSA
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13
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Advanced therapeutic strategies targeting microglia: beyond neuroinflammation. Arch Pharm Res 2022; 45:618-630. [PMID: 36166145 DOI: 10.1007/s12272-022-01406-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 09/19/2022] [Indexed: 11/02/2022]
Abstract
For a long time, microglia have been recognized as the main culprits of neuroinflammatory responses because they are primary phagocytes present in the parenchyma of the central nervous system (CNS). However, with the evolving concept of microglial biology, advanced and precise approaches, rather than the global inhibition of activated microglia, have been proposed in the management of neurological disorders. Yolk sac-derived resident microglia have heterogeneous composition according to brain region, sex, and diseases. They play a key role in the maintenance of CNS homeostasis and as primary phagocytes. The perturbation of microglia development can induce neurodevelopmental disorders. Microglia aggravate or alleviate neuroinflammation according to microenvironment and their spatiotemporal dynamics. They are long-lived cells and repopulate via their proliferation or external monocyte engraft. Based on this evolving concept, understanding advanced therapeutic strategies targeting microglia can give us an opportunity to discover novel therapies for neurological disorders.
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14
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Mehl LC, Manjally AV, Bouadi O, Gibson EM, Tay TL. Microglia in brain development and regeneration. Development 2022; 149:275253. [PMID: 35502782 PMCID: PMC9124570 DOI: 10.1242/dev.200425] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It has recently emerged that microglia, the tissue-resident macrophages of the central nervous system, play significant non-innate immune roles to support the development, maintenance, homeostasis and repair of the brain. Apart from being highly specialized brain phagocytes, microglia modulate the development and functions of neurons and glial cells through both direct and indirect interactions. Thus, recognizing the elements that influence the homeostasis and heterogeneity of microglia in normal brain development is crucial to understanding the mechanisms that lead to early disease pathogenesis of neurodevelopmental disorders. In this Review, we discuss recent studies that have elucidated the physiological development of microglia and summarize our knowledge of their non-innate immune functions in brain development and tissue repair.
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Affiliation(s)
- Lindsey C Mehl
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | | | - Ouzéna Bouadi
- Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany
| | - Erin M Gibson
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Tuan L Tay
- Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany.,BrainLinks-BrainTools Centre, University of Freiburg, Freiburg, 79110, Germany.,Freiburg Institute of Advanced Studies, University of Freiburg, Freiburg, 79104, Germany
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15
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Rosin JM, Tretiakov N, Hanniman E, Hampton K, Kurrasch DM. Gestational Bisphenol A Exposure Impacts Embryonic Hypothalamic Microglia Numbers, Ramification, and Phagocytic Cups. Front Neurosci 2022; 16:830399. [PMID: 35250464 PMCID: PMC8894877 DOI: 10.3389/fnins.2022.830399] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/21/2022] [Indexed: 12/20/2022] Open
Abstract
Microglia are a resident population of phagocytic immune cells that reside within the central nervous system (CNS). During gestation, they are highly sensitive to their surrounding environment and can alter their physiology to respond to perceived neural insults, potentially leading to adverse influences on nearby neural progenitors. Given that bisphenol A (BPA) itself can impact developing brains, and that microglia express estrogen receptors to which BPA can bind, here we asked whether fetal microglia are responsive to gestational BPA exposure. Accordingly, we exposed pregnant dams to control or 50 mg of BPA per kg diet during gestation to investigate the impact of maternal BPA on embryonic hypothalamic microglia. Gestational BPA exposure from embryonic day 0.5 (E0.5) to E15.5 resulted in a significant increase in the number of microglia present in the hypothalamus of both male and female embryos. Staining for microglial activation using CD68 showed no change between control and prenatal BPA-exposed microglia, regardless of sex. Similarly, analysis of cultured embryonic brains demonstrated that gestational BPA exposure failed to change the secretion of cytokines or chemokines, regardless of embryo sex or the dose (50 μg of BPA per kg or 50 mg of BPA per kg maternal diet) of BPA treatment. In contrast, live-cell imaging of microglia dynamics in E15.5 control and gestationally-exposed BPA hypothalamic slices showed increased ramification of microglia exposed to BPA. Moreover, live-cell imaging also revealed a significant increase in the number of microglial phagocytic cups visible following exposure to gestational BPA. Together, these results suggest that gestational BPA exposure impacts embryonic hypothalamic microglia, perhaps leading them to alter their interactions with developing neural programs.
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Affiliation(s)
- Jessica M. Rosin
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Jessica M. Rosin,
| | - Nikol Tretiakov
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Emily Hanniman
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Kiana Hampton
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Deborah M. Kurrasch
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Deborah M. Kurrasch,
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16
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Koshko L, Scofield S, Mor G, Sadagurski M. Prenatal Pollutant Exposures and Hypothalamic Development: Early Life Disruption of Metabolic Programming. Front Endocrinol (Lausanne) 2022; 13:938094. [PMID: 35909533 PMCID: PMC9327615 DOI: 10.3389/fendo.2022.938094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/13/2022] [Indexed: 11/23/2022] Open
Abstract
Environmental contaminants in ambient air pollution pose a serious risk to long-term metabolic health. Strong evidence shows that prenatal exposure to pollutants can significantly increase the risk of Type II Diabetes (T2DM) in children and all ethnicities, even without the prevalence of obesity. The central nervous system (CNS) is critical in regulating whole-body metabolism. Within the CNS, the hypothalamus lies at the intersection of the neuroendocrine and autonomic systems and is primarily responsible for the regulation of energy homeostasis and satiety signals. The hypothalamus is particularly sensitive to insults during early neurodevelopmental periods and may be susceptible to alterations in the formation of neural metabolic circuitry. Although the precise molecular mechanism is not yet defined, alterations in hypothalamic developmental circuits may represent a leading cause of impaired metabolic programming. In this review, we present the current knowledge on the links between prenatal pollutant exposure and the hypothalamic programming of metabolism.
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Affiliation(s)
- Lisa Koshko
- Integrative Biosciences Center, Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Sydney Scofield
- Integrative Biosciences Center, Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Gil Mor
- C.S. Mott Center for Human Growth and Development, Department of Obstetrics and Gynecology School of Medicine, Wayne State University, Detroit, MI, United States
| | - Marianna Sadagurski
- Integrative Biosciences Center, Department of Biological Sciences, Wayne State University, Detroit, MI, United States
- *Correspondence: Marianna Sadagurski,
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17
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Microglia-like Cells Promote Neuronal Functions in Cerebral Organoids. Cells 2021; 11:cells11010124. [PMID: 35011686 PMCID: PMC8750120 DOI: 10.3390/cells11010124] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 12/17/2022] Open
Abstract
Human cerebral organoids, derived from induced pluripotent stem cells, offer a unique in vitro research window to the development of the cerebral cortex. However, a key player in the developing brain, the microglia, do not natively emerge in cerebral organoids. Here we show that erythromyeloid progenitors (EMPs), differentiated from induced pluripotent stem cells, migrate to cerebral organoids, and mature into microglia-like cells and interact with synaptic material. Patch-clamp electrophysiological recordings show that the microglia-like population supported the emergence of more mature and diversified neuronal phenotypes displaying repetitive firing of action potentials, low-threshold spikes and synaptic activity, while multielectrode array recordings revealed spontaneous bursting activity and increased power of gamma-band oscillations upon pharmacological challenge with NMDA. To conclude, microglia-like cells within the organoids promote neuronal and network maturation and recapitulate some aspects of microglia-neuron co-development in vivo, indicating that cerebral organoids could be a useful biorealistic human in vitro platform for studying microglia-neuron interactions.
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18
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Clabough E, Ingersoll J, Reekes T, Gleichsner A, Ryan A. Acute Ethanol Exposure during Synaptogenesis Rapidly Alters Medium Spiny Neuron Morphology and Synaptic Protein Expression in the Dorsal Striatum. Int J Mol Sci 2021; 23:290. [PMID: 35008713 PMCID: PMC8745582 DOI: 10.3390/ijms23010290] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 12/26/2022] Open
Abstract
Fetal alcohol spectrum disorders are caused by the disruption of normal brain development in utero. The severity and range of symptoms is dictated by both the dosage and timing of ethanol administration, and the resulting developmental processes that are impacted. In order to investigate the effects of an acute, high-dose intoxication event on the development of medium spiny neurons (MSNs) in the striatum, mice were injected with ethanol on P6, and neuronal morphology was assessed after 24 h, or at 1 month or 5 months of age. Data indicate an immediate increase in MSN dendritic length and branching, a rapid decrease in spine number, and increased levels of the synaptic protein PSD-95 as a consequence of this neonatal exposure to ethanol, but these differences do not persist into adulthood. These results demonstrate a rapid neuronal response to ethanol exposure and characterize the dynamic nature of neuronal architecture in the MSNs. Although differences in neuronal branching and spine density induced by ethanol resolve with time, early changes in the caudate/putamen region have a potential impact on the execution of complex motor skills, as well as aspects of long-term learning and addictive behavior.
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Affiliation(s)
- Erin Clabough
- Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA
| | - James Ingersoll
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA; (J.I.); (T.R.)
| | - Tyler Reekes
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA; (J.I.); (T.R.)
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA 71104, USA
| | - Alyssa Gleichsner
- Department of Biological Science, SUNY Plattsburgh, Plattsburgh, NY 12901, USA; (A.G.); (A.R.)
| | - Amy Ryan
- Department of Biological Science, SUNY Plattsburgh, Plattsburgh, NY 12901, USA; (A.G.); (A.R.)
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19
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Wang S, Ren D, Arkoun B, Kaushik AL, Matherat G, Lécluse Y, Filipp D, Vainchenker W, Raslova H, Plo I, Godin I. Lyl-1 regulates primitive macrophages and microglia development. Commun Biol 2021; 4:1382. [PMID: 34887504 PMCID: PMC8660792 DOI: 10.1038/s42003-021-02886-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 11/10/2021] [Indexed: 12/22/2022] Open
Abstract
During ontogeny, macrophage populations emerge in the Yolk Sac (YS) via two distinct progenitor waves, prior to hematopoietic stem cell development. Macrophage progenitors from the primitive/"early EMP" and transient-definitive/"late EMP" waves both contribute to various resident primitive macrophage populations in the developing embryonic organs. Identifying factors that modulates early stages of macrophage progenitor development may lead to a better understanding of defective function of specific resident macrophage subsets. Here we show that YS primitive macrophage progenitors express Lyl-1, a bHLH transcription factor related to SCL/Tal-1. Transcriptomic analysis of YS macrophage progenitors indicate that primitive macrophage progenitors present at embryonic day 9 are clearly distinct from those present at later stages. Disruption of Lyl-1 basic helix-loop-helix domain leads initially to an increased emergence of primitive macrophage progenitors, and later to their defective differentiation. These defects are associated with a disrupted expression of gene sets related to embryonic patterning and neurodevelopment. Lyl-1-deficiency also induce a reduced production of mature macrophages/microglia in the early brain, as well as a transient reduction of the microglia pool at midgestation and in the newborn. We thus identify Lyl-1 as a critical regulator of primitive macrophages and microglia development, which disruption may impair resident-macrophage function during organogenesis.
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Affiliation(s)
- Shoutang Wang
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France ,grid.4367.60000 0001 2355 7002Present Address: Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Deshan Ren
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France ,grid.41156.370000 0001 2314 964XPresent Address: Ministry of Education Key Laboratory of Model Animal for Disease study; Model Animal Research Center, Medical school of Nanjing University, Chemistry and Biomedicine Innovation center, Nanjing University, Nanjing, 210093 China
| | - Brahim Arkoun
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France
| | - Anna-Lila Kaushik
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France ,Present Address: Plasseraud IP, 33064 Bordeaux, France
| | - Gabriel Matherat
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France ,grid.22058.3d0000 0001 2104 254XPresent Address: Agence Nationale pour la Recherche, Paris, France
| | - Yann Lécluse
- grid.14925.3b0000 0001 2284 9388PFIC, lUMS AMMICa (US 23 INSERM/UMS 3655 CNRS; Gustave Roussy, Villejuif, France
| | - Dominik Filipp
- grid.418827.00000 0004 0620 870XLaboratory of Immunobiology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - William Vainchenker
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France
| | - Hana Raslova
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France
| | - Isabelle Plo
- grid.14925.3b0000 0001 2284 9388Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France
| | - Isabelle Godin
- Gustave Roussy, INSERM UMR1287, Université Paris-Saclay, Villejuif, France.
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20
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Zhang L, Cao Y, Zhang X, Gu X, Mao Y, Peng B. The origin and repopulation of microglia. Dev Neurobiol 2021; 82:112-124. [PMID: 34874111 DOI: 10.1002/dneu.22862] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/17/2021] [Accepted: 11/20/2021] [Indexed: 12/23/2022]
Abstract
Microglia are important immune cells in the central nervous system. There is growing interest in the study of microglia due to their implication in neurodevelopment, acute injury, and neuropsychiatric disorders. They undergo birth, death, and regeneration during the lifetime. Although data on the ontogeny of microglia have been studied for decades, the birth and repopulation of microglia remain legendary and mysterious. In this review, we discuss recent studies that provide new insights into the origin and regeneration of microglia. Modulating the development of microglia may offer new therapeutic opportunities for preventing deleterious effects of inflammation and controlling excessive inflammation in brain diseases.
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Affiliation(s)
- Lijuan Zhang
- Department of Neurosurgery, Huashan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Yue Cao
- Department of Neurosurgery, Huashan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Xin Zhang
- Department of Neurosurgery, Huashan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Xinyang Gu
- Department of Neurosurgery, Huashan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Ying Mao
- Department of Neurosurgery, Huashan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Bo Peng
- Department of Neurosurgery, Huashan Hospital, Institute for Translational Brain Research, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
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21
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Sobierajski E, Lauer G, Aktas M, Beemelmans C, Beemelmans C, Meyer G, Wahle P. Development of microglia in fetal and postnatal neocortex of the pig, the European wild boar (Sus scrofa). J Comp Neurol 2021; 530:1341-1362. [PMID: 34817865 DOI: 10.1002/cne.25280] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 01/01/2023]
Abstract
Knowledge on cortical development is based mainly on rodents besides primates and carnivores, all being altricial. Here, we analyzed a precocial animal, the pig, looking at dorsoparietal cortex from E45 to P90. At E45, most ionized calcium-binding adapter molecule 1-positive (Iba1+) cells had a macrophage-like morphology and resided in meninges and choroid plexus. Only a few cells were scattered in the ventricular and subventricular zone (VZ and SVZ). At E60/E70, all laminar compartments displayed microglia cells at a low-to-moderate density, being highest in VZ and SVZ followed by intermediate zone/white matter (IZ/WM). The cortical plate and marginal zone displayed only a few Iba1+ cells. Cells were intensely labeled, but still had poorly arborized somata and many resembled ameboid, macrophage-like microglia. Concurrent with a massive increase in cortical volume, microglia cell density increased until E85, and further until E100/E110 (birth at E114) to densities that resemble those seen postnatally. A fraction of microglia colabeled with Ki67 suggesting proliferation in all laminar compartments. Cell-to-cell distance decreased substantially during this time, and the fraction of microglia to all nuclei and to neurons increases in the laminar compartments. Eventually, of all cortical DAPI+ nuclei 7-12% were Iba1+ microglia. From E70 onwards, more and more cells with ramified processes were present in MZ down to IZ/WM, showing, for instance, a close association with NeuN+, NPY+, and GAD65/67+ somata and axon initial segments. These results suggested that the development of microglia cell density and morphology proceeds rapidly from mid-gestation onwards reaching near-adult status already before birth.
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Affiliation(s)
- Eric Sobierajski
- Department of Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - German Lauer
- Department of Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Meriyem Aktas
- Department of Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | | | | | - Gundela Meyer
- Department of Basic Medical Science, Faculty of Medicine, University of La Laguna, Tenerife, Spain
| | - Petra Wahle
- Department of Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
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22
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Carbon Monoxide Modulation of Microglia-Neuron Communication: Anti-Neuroinflammatory and Neurotrophic Role. Mol Neurobiol 2021; 59:872-889. [PMID: 34796462 DOI: 10.1007/s12035-021-02643-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/09/2021] [Indexed: 10/19/2022]
Abstract
Microglia, the 'resident immunocompetent cells' of the central nervous system (CNS), are key players in innate immunity, synaptic refinement and homeostasis. Dysfunctional microglia contribute heavily to creating a toxic inflammatory milieu, a driving factor in the pathophysiology of several CNS disorders. Therefore, strategies to modulate the microglial function are required to tackle exacerbated tissue inflammation. Carbon monoxide (CO), an endogenous gaseous molecule produced by the degradation of haem, has anti-inflammatory, anti-apoptotic, and pro-homeostatic and cytoprotective roles, among others. ALF-826A, a novel molybdenum-based CO-releasing molecule, was used for the assessment of neuron-microglia remote communication. Primary cultures of rat microglia and neurons, or the BV-2 microglial and CAD neuronal murine cell lines, were used to study the microglia-neuron interaction. An approach based on microglial-derived conditioned media in neuronal culture was applied. Medium derived from CO-treated microglia provided indirect neuroprotection against inflammation by limiting the lipopolysaccharide (LPS)-induced expression of reactivity markers (CD11b), the production of reactive oxygen species (ROS) and the secretion of inflammatory factors (TNF-α, nitrites). This consequently prevented neuronal cell death and maintained neuronal morphology. In contrast, in the absence of inflammatory stimulus, conditioned media from CO-treated microglia improved neuronal morphological complexity, which is an indirect manner of assessing neuronal function. Likewise, the microglial medium also prevented neuronal cell death induced by pro-oxidant tert-Butyl hydroperoxide (t-BHP). ALF-826 treatment reinforced microglia secretion of Interleukin-10 (IL-10) and adenosine, mediators that may protect against t-BHP stress in this remote communication model. Chemical inhibition of the adenosine receptors A2A and A1 reverted the CO-derived neuroprotective effect, further highlighting a role for CO in regulating neuron-microglia communication via purinergic signalling. Our findings indicate that CO has a modulatory role on microglia-to-neuron communication, promoting neuroprotection in a non-cell autonomous manner. CO enhances the microglial release of neurotrophic factors and blocks exacerbated microglial inflammation. CO improvement of microglial neurotrophism under non-inflammatory conditions is here described for the first time.
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23
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Blank N, Mayer M, Mass E. The development and physiological and pathophysiological functions of resident macrophages and glial cells. Adv Immunol 2021; 151:1-47. [PMID: 34656287 DOI: 10.1016/bs.ai.2021.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In the past, brain function and the onset and progression of neurological diseases have been studied in a neuron-centric manner. However, in recent years the focus of many neuroscientists has shifted to other cell types that promote neurodevelopment and contribute to the functionality of neuronal networks in health and disease. Particularly microglia and astrocytes have been implicated in actively contributing to and controlling neuronal development, neuroinflammation, and neurodegeneration. Here, we summarize the development of brain-resident macrophages and astrocytes and their core functions in the developing brain. We discuss their contribution and intercellular crosstalk during tissue homeostasis and pathophysiology. We argue that in-depth knowledge of non-neuronal cells in the brain could provide novel therapeutic targets to reverse or contain neurological diseases.
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Affiliation(s)
- Nelli Blank
- Developmental Biology of the Immune System, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.
| | - Marina Mayer
- Developmental Biology of the Immune System, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Elvira Mass
- Developmental Biology of the Immune System, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.
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24
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Soares NL, Vieira HLA. Microglia at the Centre of Brain Research: Accomplishments and Challenges for the Future. Neurochem Res 2021; 47:218-233. [PMID: 34586585 DOI: 10.1007/s11064-021-03456-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 02/08/2023]
Abstract
Microglia are the immune guardians of the central nervous system (CNS), with critical functions in development, maintenance of homeostatic tissue balance, injury and repair. For a long time considered a forgotten 'third element' with basic phagocytic functions, a recent surge in interest, accompanied by technological progress, has demonstrated that these distinct myeloid cells have a wide-ranging importance for brain function. This review reports microglial origins, development, and function in the healthy brain. Moreover, it also targets microglia dysfunction and how it contributes to the progression of several neurological disorders, focusing on particular molecular mechanisms and whether these may present themselves as opportunities for novel, microglia-targeted therapeutic approaches, an ever-enticing prospect. Finally, as it has been recently celebrated 100 years of microglia research, the review highlights key landmarks from the past century and looked into the future. Many challenging problems have arisen, thus it points out some of the most pressing questions and experimental challenges for the ensuing century.
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Affiliation(s)
- Nuno L Soares
- Chronic Diseases Research Center (CEDOC) - Faculdade de Ciências Médicas/NOVA Medical School, Universidade Nova de Lisboa, Campo dos Mártires da Pátria 130, 1169-056, Lisboa, Portugal.
| | - Helena L A Vieira
- Chronic Diseases Research Center (CEDOC) - Faculdade de Ciências Médicas/NOVA Medical School, Universidade Nova de Lisboa, Campo dos Mártires da Pátria 130, 1169-056, Lisboa, Portugal.,Department of Chemistry, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, Universidade Nova de Lisboa, Lisboa, Portugal.,Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Lisboa, Portugal
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25
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Abstract
Microglia are the resident immune cells of the central nervous system. Microglial progenitors are generated in the yolk sac during the early embryonic stage. Once microglia enter the brain primordium, these cells colonize the structure through migration and proliferation during brain development. Microglia account for a minor population among the total cells that constitute the developing cortex, but they can associate with many surrounding neural lineage cells by extending their filopodia and through their broad migration capacity. Of note, microglia change their distribution in a stage-dependent manner in the developing brain: microglia are homogenously distributed in the pallium in the early and late embryonic stages, whereas these cells are transiently absent from the cortical plate (CP) from embryonic day (E) 15 to E16 and colonize the ventricular zone (VZ), subventricular zone (SVZ), and intermediate zone (IZ). Previous studies have reported that microglia positioned in the VZ/SVZ/IZ play multiple roles in neural lineage cells, such as regulating neurogenesis, cell survival and neuronal circuit formation. In addition to microglial functions in the zones in which microglia are replenished, these cells indirectly contribute to the proper maturation of post-migratory neurons by exiting the CP during the mid-embryonic stage. Overall, microglial time-dependent distributional changes are necessary to provide particular functions that are required in specific regions. This review summarizes recent advances in the understanding of microglial colonization and multifaceted functions in the developing brain, especially focusing on the embryonic stage, and discuss the molecular mechanisms underlying microglial behaviors.
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Hanslik KL, Marino KM, Ulland TK. Modulation of Glial Function in Health, Aging, and Neurodegenerative Disease. Front Cell Neurosci 2021; 15:718324. [PMID: 34531726 PMCID: PMC8439422 DOI: 10.3389/fncel.2021.718324] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/27/2021] [Indexed: 01/15/2023] Open
Abstract
In the central nervous system (CNS), glial cells, such as microglia and astrocytes, are normally associated with support roles including contributions to energy metabolism, synaptic plasticity, and ion homeostasis. In addition to providing support for neurons, microglia and astrocytes function as the resident immune cells in the brain. The glial function is impacted by multiple aspects including aging and local CNS changes caused by neurodegeneration. During aging, microglia and astrocytes display alterations in their homeostatic functions. For example, aged microglia and astrocytes exhibit impairments in the lysosome and mitochondrial function as well as in their regulation of synaptic plasticity. Recent evidence suggests that glia can also alter the pathology associated with many neurodegenerative disorders including Alzheimer's disease (AD) and Parkinson's disease (PD). Shifts in the microbiome can impact glial function as well. Disruptions in the microbiome can lead to aberrant microglial and astrocytic reactivity, which can contribute to an exacerbation of disease and neuronal dysfunction. In this review, we will discuss the normal physiological functions of microglia and astrocytes, summarize novel findings highlighting the role of glia in aging and neurodegenerative diseases, and examine the contribution of microglia and astrocytes to disease progression.
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Affiliation(s)
- Kendra L. Hanslik
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Kaitlyn M. Marino
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Tyler K. Ulland
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
- Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI, United States
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27
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Milinkeviciute G, Chokr SM, Castro EM, Cramer KS. CX3CR1 mutation alters synaptic and astrocytic protein expression, topographic gradients, and response latencies in the auditory brainstem. J Comp Neurol 2021; 529:3076-3097. [PMID: 33797066 DOI: 10.1002/cne.25150] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/04/2021] [Accepted: 03/27/2021] [Indexed: 01/14/2023]
Abstract
The precise and specialized circuitry in the auditory brainstem develops through adaptations of cellular and molecular signaling. We previously showed that elimination of microglia during development impairs synaptic pruning that leads to maturation of the calyx of Held, a large encapsulating synapse that terminates on neurons of the medial nucleus of the trapezoid body (MNTB). Microglia depletion also led to a decrease in glial fibrillary acidic protein (GFAP), a marker for mature astrocytes. Here, we investigated the role of signaling through the fractalkine receptor (CX3CR1), which is expressed by microglia and mediates communication with neurons. CX3CR1-/- and wild-type mice were studied before and after hearing onset and at 9 weeks of age. Levels of GFAP were significantly increased in the MNTB in mutants at 9 weeks. Pruning was unaffected at the calyx of Held, but we found an increase in expression of glycinergic synaptic marker in mutant mice at P14, suggesting an effect on maturation of inhibitory inputs. We observed disrupted tonotopic gradients of neuron and calyx size in MNTB in mutant mice. Auditory brainstem recording (ABR) revealed that CX3CR1-/- mice had normal thresholds and amplitudes but decreased latencies and interpeak latencies, particularly for the highest frequencies. These results demonstrate that disruption of fractalkine signaling has a significant effect on auditory brainstem development. Our findings highlight the importance of neuron-microglia-astrocyte communication in pruning of inhibitory synapses and establishment of tonotopic gradients early in postnatal development.
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Affiliation(s)
- Giedre Milinkeviciute
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA
| | - Sima M Chokr
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA
| | - Emily M Castro
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA
| | - Karina S Cramer
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA
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28
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Davoli-Ferreira M, Thomson CA, McCoy KD. Microbiota and Microglia Interactions in ASD. Front Immunol 2021; 12:676255. [PMID: 34113350 PMCID: PMC8185464 DOI: 10.3389/fimmu.2021.676255] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022] Open
Abstract
Autism spectrum disorders (ASD) are serious, highly variable neurodevelopmental disorders, commonly characterized by the manifestation of specific behavioral abnormalities, such as stereotypic behaviors and deficits in social skills, including communication. Although the neurobiological basis for ASD has attracted attention in recent decades, the role of microglial cells, which are the main resident myeloid cell population in the brain, is still controversial and underexplored. Microglia play several fundamental roles in orchestrating brain development and homeostasis. As such, alterations in the intrinsic functions of these cells could be one of the driving forces responsible for the development of various neurodevelopmental disorders, including ASD. Microglia are highly sensitive to environmental cues. Amongst the environmental factors known to influence their intrinsic functions, the gut microbiota has emerged as a central player, controlling both microglial maturation and activation. Strikingly, there is now compelling data suggesting that the intestinal microbiota can play a causative role in driving the behavioural changes associated with ASD. Not only is intestinal dysbiosis commonly reported in ASD patients, but therapies targeting the microbiome can markedly alleviate behavioral symptoms. Here we explore the emerging mechanisms by which altered microglial functions could contribute to several major etiological factors of ASD. We then demonstrate how pre- and postnatal environmental stimuli can modulate microglial cell phenotype and function, underpinning the notion that reciprocal interactions between microglia and intestinal microbes could play a crucial role in ASD aetiology.
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Affiliation(s)
- Marcela Davoli-Ferreira
- Department of Physiology and Pharmacology, Snyder Institute of Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Carolyn A Thomson
- Department of Physiology and Pharmacology, Snyder Institute of Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Kathy D McCoy
- Department of Physiology and Pharmacology, Snyder Institute of Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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29
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Rosin JM, Sinha S, Biernaskie J, Kurrasch DM. A subpopulation of embryonic microglia respond to maternal stress and influence nearby neural progenitors. Dev Cell 2021; 56:1326-1345.e6. [PMID: 33887203 DOI: 10.1016/j.devcel.2021.03.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 01/21/2021] [Accepted: 03/11/2021] [Indexed: 12/31/2022]
Abstract
The interplay between hypothalamic neurons and microglia as they integrate stressors to regulate homeostasis is of growing interest. We asked if microglia in the embryonic hypothalamus were likewise stress responsive and, if so, whether their precocious activation perturbs nearby neural stem cell (NSC) programs. We performed single-cell transcriptomics to define embryonic hypothalamic microglia heterogeneity and identified four microglial subsets, including a subpopulation adjacent to NSCs that was responsive to gestational cold stress. Stress exposure elevated CCL3 and CCL4 secretion, but only in male brains, and ex vivo CCL4 treatment of hypothalamic NSCs altered proliferation and differentiation. Concomitantly, gestational stress decreased PVN oxytocin neurons only in male embryos, which was reversed by microglia depletion. Adult offspring exposed to gestational stress displayed altered social behaviors, which was likewise microglia dependent, but only in males. Collectively, immature hypothalamic microglia play an unappreciated role in translating maternal stressors to sexually dimorphic perturbation of neurodevelopmental programs.
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Affiliation(s)
- Jessica M Rosin
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Sarthak Sinha
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Jeff Biernaskie
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Deborah M Kurrasch
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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30
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Sharma K, Bisht K, Eyo UB. A Comparative Biology of Microglia Across Species. Front Cell Dev Biol 2021; 9:652748. [PMID: 33869210 PMCID: PMC8047420 DOI: 10.3389/fcell.2021.652748] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/10/2021] [Indexed: 12/26/2022] Open
Abstract
Microglia are unique brain-resident, myeloid cells. They have received growing interest for their implication in an increasing number of neurodevelopmental, acute injury, and neurodegenerative disorders of the central nervous system (CNS). Fate-mapping studies establish microglial ontogeny from the periphery during development, while recent transcriptomic studies highlight microglial identity as distinct from other CNS cells and peripheral myeloid cells. This evidence for a unique microglial ontogeny and identity raises questions regarding their identity and functions across species. This review will examine the available evidence for microglia in invertebrate and vertebrate species to clarify similarities and differences in microglial identity, ontogeny, and physiology across species. This discussion highlights conserved and divergent microglial properties through evolution. Finally, we suggest several interesting research directions from an evolutionary perspective to adequately understand the significance of microglia emergence. A proper appreciation of microglia from this perspective could inform the development of specific therapies geared at targeting microglia in various pathologies.
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Affiliation(s)
- Kaushik Sharma
- Center for Brain Immunology and Glia, University of Virginia, Charlottesville, VA, United States.,Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Kanchan Bisht
- Center for Brain Immunology and Glia, University of Virginia, Charlottesville, VA, United States.,Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Ukpong B Eyo
- Center for Brain Immunology and Glia, University of Virginia, Charlottesville, VA, United States.,Department of Neuroscience, University of Virginia, Charlottesville, VA, United States
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31
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Embryonic Microglia Interact with Hypothalamic Radial Glia during Development and Upregulate the TAM Receptors MERTK and AXL following an Insult. Cell Rep 2021; 34:108587. [PMID: 33406432 DOI: 10.1016/j.celrep.2020.108587] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 09/23/2020] [Accepted: 12/10/2020] [Indexed: 02/07/2023] Open
Abstract
Despite a growing appreciation for microglial influences on the developing brain, the responsiveness of microglia to insults during gestation remains less well characterized, especially in the embryo when microglia themselves are still maturing. Here, we asked if fetal microglia could coordinate an innate immune response to an exogenous insult. Using time-lapse imaging, we showed that hypothalamic microglia actively surveyed their environment by near-constant "touching" of radial glia projections. However, following an insult (i.e., IUE or AAV transduction), this seemingly passive touching became more intimate and long lasting, ultimately resulting in the retraction of radial glial projections and degeneration into small pieces. Mechanistically, the TAM receptors MERTK and AXL were upregulated in microglia following the insult, and Annexin V treatment inhibited radial glia breakage and engulfment by microglia. These data demonstrate a remarkable responsiveness of embryonic microglia to insults during gestation, a critical window for neurodevelopment.
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32
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Lago-Baldaia I, Fernandes VM, Ackerman SD. More Than Mortar: Glia as Architects of Nervous System Development and Disease. Front Cell Dev Biol 2020; 8:611269. [PMID: 33381506 PMCID: PMC7767919 DOI: 10.3389/fcell.2020.611269] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are an essential component of the nervous system of vertebrates and invertebrates. In the human brain, glia are as numerous as neurons, yet the importance of glia to nearly every aspect of nervous system development has only been expounded over the last several decades. Glia are now known to regulate neural specification, synaptogenesis, synapse function, and even broad circuit function. Given their ubiquity, it is not surprising that the contribution of glia to neuronal disease pathogenesis is a growing area of research. In this review, we will summarize the accumulated evidence of glial participation in several distinct phases of nervous system development and organization-neural specification, circuit wiring, and circuit function. Finally, we will highlight how these early developmental roles of glia contribute to nervous system dysfunction in neurodevelopmental and neurodegenerative disorders.
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Affiliation(s)
- Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Sarah D. Ackerman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, United States
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33
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Developmental Maturation of the Cerebellar White Matter-an Instructive Environment for Cerebellar Inhibitory Interneurons. THE CEREBELLUM 2020; 19:286-308. [PMID: 32002802 PMCID: PMC7082410 DOI: 10.1007/s12311-020-01111-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the developing cerebellum, the nascent white matter (WM) serves as an instructive niche for cerebellar cortical inhibitory interneurons. As their Pax2 expressing precursors transit the emerging WM, their laminar fate is programmed. The source(s) and nature of the signals involved remain unknown. Here, we used immunocytochemistry to follow the cellular maturation of the murine cerebellar WM during this critical period. During the first few days of postnatal development, when most Pax2 expressing cells are formed and many of them reach the cerebellar gray matter, only microglial cells can be identified in the territories through which Pax2 cells migrate. From p4 onward, cells expressing the oligodendrocytic or astrocyte markers, CNP-1, MBP or GFAP, started to appear in the nascent WM. Expression of macroglial markers increased with cerebellar differentiation, yet deep nuclei remained GFAP-negative at all ages. The progressive spread of maturing glia did not correlate with the exit of Pax2 cells from the WM, as indicated by the extensive mingling of these cells up to p15. Whereas sonic hedgehog-associated p75NTR expression could be verified in granule cell precursors, postmitotic Pax2 cells are p75NTR negative at all ages analyzed. Thus, if Pax2 cells, like their precursors, are sensitive to sonic hedgehog, this does not affect their expression of p75NTR. Our findings document that subsequently generated sets of Pax2 expressing precursors of inhibitory cerebellar interneurons are confronted with a dynamically changing complement of cerebellar glia. The eventual identification of fate-defining pathways should profit from the covariation with glial maturation predicted by the present findings.
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34
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Xu P, Shan C, Dunn TJ, Xie X, Xia H, Gao J, Allende Labastida J, Zou J, Villarreal PP, Schlagal CR, Yu Y, Vargas G, Rossi SL, Vasilakis N, Shi PY, Weaver SC, Wu P. Role of microglia in the dissemination of Zika virus from mother to fetal brain. PLoS Negl Trop Dis 2020; 14:e0008413. [PMID: 32628667 PMCID: PMC7365479 DOI: 10.1371/journal.pntd.0008413] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 07/16/2020] [Accepted: 05/22/2020] [Indexed: 12/17/2022] Open
Abstract
Global Zika virus (ZIKV) outbreaks and their link to microcephaly have raised major public health concerns. However, the mechanism of maternal-fetal transmission remains largely unknown. In this study, we determined the role of yolk sac (YS) microglial progenitors in a mouse model of ZIKV vertical transmission. We found that embryonic (E) days 6.5-E8.5 were a critical window for ZIKV infection that resulted in fetal demise and microcephaly, and YS microglial progenitors were susceptible to ZIKV infection. Ablation of YS microglial progenitors significantly reduced the viral load in both the YS and the embryonic brain. Taken together, these results support the hypothesis that YS microglial progenitors serve as “Trojan horses,” contributing to ZIKV fetal brain dissemination and congenital brain defects. ZIKV is more likely to cause fetal demise and brain malformations when the mother is infected at an early stage of pregnancy, which is the critical time window when a special type of immune cells called microglia appear in the YS and migrate to the fetal brain. YS-derived microglia are susceptible to ZIKV infection and can act as “Trojan horses” to bring ZIKV from the mother to the fetal brain.
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Affiliation(s)
- Pei Xu
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Chao Shan
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Tiffany J. Dunn
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Xuping Xie
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Hongjie Xia
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Junling Gao
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Javier Allende Labastida
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jing Zou
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Paula P. Villarreal
- Center for Biomedical Engineering, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Caitlin R. Schlagal
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yongjia Yu
- Department of Radiology and Oncology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Gracie Vargas
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biomedical Engineering, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Shannan L. Rossi
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Nikolaos Vasilakis
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- World Reference Center for Emerging Viruses and Arboviruses, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Pei-Yong Shi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Scott C. Weaver
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- World Reference Center for Emerging Viruses and Arboviruses, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail: (SCW); (PW)
| | - Ping Wu
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail: (SCW); (PW)
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35
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Accogli A, Addour-Boudrahem N, Srour M. Neurogenesis, neuronal migration, and axon guidance. HANDBOOK OF CLINICAL NEUROLOGY 2020; 173:25-42. [PMID: 32958178 DOI: 10.1016/b978-0-444-64150-2.00004-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Development of the central nervous system (CNS) is a complex, dynamic process that involves a precisely orchestrated sequence of genetic, environmental, biochemical, and physical factors from early embryonic stages to postnatal life. Duringthe past decade, great strides have been made to unravel mechanisms underlying human CNS development through the employment of modern genetic techniques and experimental approaches. In this chapter, we review the current knowledge regarding the main developmental processes and signaling mechanisms of (i) neurogenesis, (ii) neuronal migration, and (iii) axon guidance. We discuss mechanisms related to neural stem cells proliferation, migration, terminal translocation of neuronal progenitors, and axon guidance and pathfinding. For each section, we also provide a comprehensive overview of the underlying regulatory processes, including transcriptional, posttranscriptional, and epigenetic factors, and a myriad of signaling pathways that are pivotal to determine the fate of neuronal progenitors and newly formed migrating neurons. We further highlight how impairment of this complex regulating system, such as mutations in its core components, may cause cortical malformation, epilepsy, intellectual disability, and autism in humans. A thorough understanding of normal human CNS development is thus crucial to decipher mechanisms responsible for neurodevelopmental disorders and in turn guide the development of effective and targeted therapeutic strategies.
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Affiliation(s)
- Andrea Accogli
- Unit of Medical Genetics, Istituto Giannina Gaslini Pediatric Hospital, Genova, Italy; Departments of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal-Child Science, Università degli Studi di Genova, Genova, Italy
| | | | - Myriam Srour
- Research Institute, McGill University Health Centre, Montreal, QC, Canada; Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montreal, QC, Canada.
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36
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Convergence between Microglia and Peripheral Macrophages Phenotype during Development and Neuroinflammation. J Neurosci 2019; 40:784-795. [PMID: 31818979 DOI: 10.1523/jneurosci.1523-19.2019] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/18/2019] [Accepted: 10/23/2019] [Indexed: 12/30/2022] Open
Abstract
Differently from other myeloid cells, microglia derive exclusively from precursors originating within the yolk sac and migrate to the CNS under development, without any contribution from fetal liver or postnatal hematopoiesis. Consistent with their unique ontology, microglia may express specific physiological markers, which have been partly described in recent years. Here we wondered whether profiles distinguishing microglia from peripheral macrophages vary with age and under pathology. To this goal, we profiled transcriptomes of microglia throughout the lifespan and included a parallel comparison with peripheral macrophages under physiological and neuroinflammatory settings using age- and sex-matched wild-type and bone marrow chimera mouse models. This comprehensive approach demonstrated that the phenotypic differentiation between microglia and peripheral macrophages is age-dependent and that peripheral macrophages do express some of the most commonly described microglia-specific markers early during development, such as Fcrls, P2ry12, Tmem119, and Trem2. Further, during chronic neuroinflammation CNS-infiltrating macrophages and not peripheral myeloid cells acquire microglial markers, indicating that the CNS niche may instruct peripheral myeloid cells to gain the phenotype and, presumably, the function of the microglia cell. In conclusion, our data provide further evidence about the plasticity of the myeloid cell and suggest caution in the strict definition and application of microglia-specific markers.SIGNIFICANCE STATEMENT Understanding the respective role of microglia and infiltrating monocytes in neuroinflammatory conditions has recently seemed possible by the identification of a specific microglia signature. Here instead we provide evidence that peripheral macrophages may express some of the most commonly described microglia markers at some developmental stages or pathological conditions, in particular during chronic neuroinflammation. Further, our data support the hypothesis about phenotypic plasticity and convergence among distinct myeloid cells so that they may act as a functional unit rather than as different entities, boosting their mutual functions in different phases of disease. This holds relevant implications in the view of the growing use of myeloid cell therapies to treat brain disease in humans.
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37
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Pecheva D, Lee A, Poh JS, Chong YS, Shek LP, Gluckman PD, Meaney MJ, Fortier MV, Qiu A. Neural Transcription Correlates of Multimodal Cortical Phenotypes during Development. Cereb Cortex 2019; 30:2740-2754. [PMID: 31773128 DOI: 10.1093/cercor/bhz271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/23/2019] [Accepted: 09/17/2019] [Indexed: 01/01/2023] Open
Abstract
During development, cellular events such as cell proliferation, migration, and synaptogenesis determine the structural organization of the brain. These processes are driven in part by spatiotemporally regulated gene expression. We investigated how the genetic signatures of specific neural cell types shape cortical organization of the human brain throughout infancy and childhood. Using a transcriptional atlas and in vivo magnetic resonance imaging (MRI) data, we demonstrated time-dependent associations between the expression levels of neuronal and glial genes and cortical macro- and microstructure. Neonatal cortical phenotypes were associated with prenatal glial but not neuronal gene expression. These associations reflect cell migration and proliferation during fetal development. Childhood cortical phenotypes were associated with neuronal and astrocyte gene expression related to synaptic signaling processes, reflecting the refinement of cortical connections. These findings indicate that sequential developmental stages contribute to distinct MRI measures at different time points. This helps to bridge the gap between the genetic mechanisms driving cellular changes and widely used neuroimaging techniques.
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Affiliation(s)
- Diliana Pecheva
- Department of Biomedical Engineering and Clinical Imaging Research Center, National University of Singapore, Singapore
| | - Annie Lee
- Department of Biomedical Engineering and Clinical Imaging Research Center, National University of Singapore, Singapore
| | - Joann S Poh
- Department of Biomedical Engineering and Clinical Imaging Research Center, National University of Singapore, Singapore
| | - Yap-Seng Chong
- Singapore Institute for Clinical Sciences, Singapore.,Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
| | - Lynette P Shek
- Department of Pediatrics, Khoo Teck Puat-National University Children's Medical Institute, National University of Singapore, Singapore
| | | | | | - Marielle V Fortier
- Department of Diagnostic and Interventional Imaging, KK Women's and Children's Hospital, Singapore
| | - Anqi Qiu
- Department of Biomedical Engineering and Clinical Imaging Research Center, National University of Singapore, Singapore
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38
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Baaklini CS, Rawji KS, Duncan GJ, Ho MFS, Plemel JR. Central Nervous System Remyelination: Roles of Glia and Innate Immune Cells. Front Mol Neurosci 2019; 12:225. [PMID: 31616249 PMCID: PMC6764409 DOI: 10.3389/fnmol.2019.00225] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/04/2019] [Indexed: 12/31/2022] Open
Abstract
In diseases such as multiple sclerosis (MS), inflammation can injure the myelin sheath that surrounds axons, a process known as demyelination. The spontaneous regeneration of myelin, called remyelination, is associated with restoration of function and prevention of axonal degeneration. Boosting remyelination with therapeutic intervention is a promising new approach that is currently being tested in several clinical trials. The endogenous regulation of remyelination is highly dependent on the immune response. In this review article, we highlight the cell biology of remyelination and its regulation by innate immune cells. For the purpose of this review, we discuss the roles of microglia, and also astrocytes and oligodendrocyte progenitor cells (OPCs) as they are being increasingly recognized to have immune cell functions.
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Affiliation(s)
- Charbel S Baaklini
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Khalil S Rawji
- Wellcome Trust-Medical Research Council, Cambridge Stem Cell Institute, Cambridge Biomedical Campus, University of Cambridge, Cambridge, United Kingdom
| | - Greg J Duncan
- Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health and Science University, Portland, OR, United States
| | - Madelene F S Ho
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Jason R Plemel
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada.,Wellcome Trust-Medical Research Council, Cambridge Stem Cell Institute, Cambridge Biomedical Campus, University of Cambridge, Cambridge, United Kingdom.,Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health and Science University, Portland, OR, United States
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Milinkeviciute G, Henningfield CM, Muniak MA, Chokr SM, Green KN, Cramer KS. Microglia Regulate Pruning of Specialized Synapses in the Auditory Brainstem. Front Neural Circuits 2019; 13:55. [PMID: 31555101 PMCID: PMC6722190 DOI: 10.3389/fncir.2019.00055] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 07/30/2019] [Indexed: 11/13/2022] Open
Abstract
The assembly of uniquely organized sound localization circuits in the brainstem requires precise developmental mechanisms. Glial cells have been shown to shape synaptic connections in the retinogeniculate system during development, but their contributions to specialized auditory synapses have not been identified. Here we investigated the role of microglia in auditory brainstem circuit assembly, focusing on the formation and pruning of the calyx of Held in the medial nucleus of the trapezoid body (MNTB). Microglia were pharmacologically depleted in mice early in development using subcutaneous injections of an inhibitor of colony stimulating factor 1 receptor, which is essential for microglia survival. Brainstems were examined prior to and just after hearing onset, at postnatal days (P) 8 and P13, respectively. We found that at P13 there were significantly more polyinnervated MNTB neurons when microglia were depleted, consistent with a defect in pruning. Expression of glial fibrillary acidic protein (GFAP), a mature astrocyte marker that normally appears in the MNTB late in development, was significantly decreased in microglia-depleted mice at P13, suggesting a delay in astrocyte maturation. Our results demonstrate that monoinnervation of MNTB neurons by the calyx of Held is significantly disrupted or delayed in the absence of microglia. This finding may reflect a direct role for microglia in synaptic pruning. A secondary role for microglia may be in the maturation of astrocytes in MNTB. These findings highlight the significant function of glia in pruning during calyx of Held development.
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Affiliation(s)
- Giedre Milinkeviciute
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Caden M. Henningfield
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Michael A. Muniak
- Vollum Institute, Oregon Health & Science University, Portland, OR, United States
- Hearing Research, Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, UNSW Sydney, Sydney, NSW, Australia
| | - Sima M. Chokr
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Kim N. Green
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Karina S. Cramer
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
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40
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Rosin JM, Kurrasch DM. Emerging roles for hypothalamic microglia as regulators of physiological homeostasis. Front Neuroendocrinol 2019; 54:100748. [PMID: 31059719 DOI: 10.1016/j.yfrne.2019.100748] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/24/2019] [Accepted: 05/02/2019] [Indexed: 01/22/2023]
Abstract
The hypothalamus is a crucial brain region that responds to external stressors and functions to maintain physiological homeostatic processes, such as core body temperature and energy balance. The hypothalamus regulates homeostasis by producing hormones that thereby influence the production of other hormones that then control the internal milieu of the body. Microglia are resident macrophages and phagocytic immune cells of the central nervous system (CNS), classically known for surveying the brain's environment, responding to neural insults, and disposing of cellular debris. Recent evidence has shown that microglia are also responsive to external stressors and can influence both the development and function of the hypothalamus in a sex-dependent manner. This emerging microglia-hypothalamic interaction raises the intriguing notion that microglia might play an unappreciated role in hypothalamic control of physiological homeostasis. In this review, we briefly outline how the hypothalamus regulates physiological homeostasis and then describe how this literature overlaps with our understanding of microglia's role in the CNS. We also outline the current literature demonstrating how microglia loss or activation affects the hypothalamus, and ultimately homeostasis. We conclude by proposing how microglia could be key regulators of homeostatic processes by sensing cues external to the CNS and transmitting them through the hypothalamus.
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Affiliation(s)
- Jessica M Rosin
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Deborah M Kurrasch
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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41
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Microglia along sex lines: From brain colonization, maturation and function, to implication in neurodevelopmental disorders. Semin Cell Dev Biol 2019; 94:152-163. [PMID: 31201858 DOI: 10.1016/j.semcdb.2019.06.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 12/30/2022]
Abstract
In addition to their traditional role as immune sentinels, recent discoveries over the last decade have shown that microglial functions now include regulation of neuronal/glial cell migration, differentiation and maturation, as well as neuronal network formation. It was thus proposed that disruption of these microglial roles, during critical periods of brain development, could lead to the pathological onset of several neurodevelopmental disorders, including autism spectrum disorder, attention deficit hyperactivity disorder, epilepsy, schizophrenia, and major depressive disorder. The prevalence of these disorders exhibits a clear distinction along sex lines with very little known about the mechanisms underlying this difference. One of the fundamental discoveries that arose from recent research into the physiological roles of microglia in neurodevelopment is their sexual dimorphism, raising the intriguing possibility that sex differences in microglial colonization, maturation and/or function in the developing brain could underlie the emergence of various neurodevelopmental disorders. This review discusses the physiological roles of microglia across neurodevelopment, these roles in the two sexes, and the recent evidence that microglial sexually dimorphic nature may contribute, at least partially, to neurodevelopmental disorders.
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Neuregulin-1 Fosters Supportive Interactions between Microglia and Neural Stem/Progenitor Cells. Stem Cells Int 2019; 2019:8397158. [PMID: 31089334 PMCID: PMC6476022 DOI: 10.1155/2019/8397158] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/31/2018] [Accepted: 02/13/2019] [Indexed: 01/23/2023] Open
Abstract
Microglia play diverse roles in homeostasis and pathology of the central nervous system (CNS). Their response to injury or insult is critical for initiating neuroinflammation and tissue damage as well as resolution of inflammation and wound healing. Changes to the microenvironment of microglia appear to be a key determinant of their phenotype and their role in the endogenous repair process in the injured or diseased CNS. Our recent findings have identified a positive role for neuregulin-1 (Nrg-1) in regulating immune response in spinal cord injury and focal demyelinating lesions. We show that increasing the tissue availability of Nrg-1 after injury can promote endogenous repair by modulating neuroinflammation. In the present study, we sought to elucidate the specific role of Nrg-1 in regulating microglial activity and more importantly their influence on the behavior of neural stem/progenitor cells (NPCs). Using injury-relevant in vitro systems, we demonstrate that Nrg-1 attenuates the expression of proinflammatory mediators in activated microglia. Moreover, we provide novel evidence that availability of Nrg-1 can restore the otherwise suppressed phagocytic ability of proinflammatory microglia. Interestingly, the presence of Nrg-1 in the microenvironment of proinflammatory microglia mitigates their inhibitory effects on NPC proliferation. Nrg-1 treated proinflammatory microglia also augment mobilization of NPCs, while they had no influence on their suppressive effects on NPC differentiation. Mechanistically, we show that Nrg-1 enhances the interactions of proinflammatory microglia and NPCs, at least in part, through reduction of TNF-α expression in microglia. These findings provide new insights into the endogenous regulation of microglia-NPC interactions and identify new potential targets for optimizing this important crosstalk during the regenerative process after CNS injury and neuroinflammatory conditions.
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Smolders SMT, Kessels S, Vangansewinkel T, Rigo JM, Legendre P, Brône B. Microglia: Brain cells on the move. Prog Neurobiol 2019; 178:101612. [PMID: 30954517 DOI: 10.1016/j.pneurobio.2019.04.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/13/2019] [Accepted: 04/01/2019] [Indexed: 02/08/2023]
Abstract
In the last decade, tremendous progress has been made in understanding the biology of microglia - i.e. the fascinating immigrated resident immune cell population of the central nervous system (CNS). Recent literature reviews have largely dealt with the plentiful functions of microglia in CNS homeostasis, development and pathology, and the influences of sex and the microbiome. In this review, the intriguing aspect of their physical plasticity during CNS development will get specific attention. Microglia move around (mobility) and reshape their processes (motility). Microglial migration into and inside the CNS is most prominent throughout development and consequently most of the data described in this review concern mobility and motility in the changing environment of the developing brain. Here, we first define microglia based on their highly specialized age- and region-dependent gene expression signature and associated functional heterogeneity. Next, we describe their origin, the migration route of immature microglial cells towards the CNS, the mechanisms underlying their invasion of the CNS, and their spatiotemporal localization and surveying behaviour inside the developing CNS. These processes are dependent on microglial mobility and motility which are determined by the microenvironment of the CNS. Therefore, we further zoom in on the changing environment during CNS development. We elaborate on the extracellular matrix and the respective integrin receptors on microglia and we discuss the purinergic and molecular signalling in microglial mobility. In the last section, we discuss the physiological and pathological functions of microglia in which mobility and motility are involved to stress the importance of microglial 'movement'.
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Affiliation(s)
- Sophie Marie-Thérèse Smolders
- UHasselt, BIOMED, Diepenbeek, Belgium; INSERM, UMR-S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Paris, France; Sorbonne Universités, UPMC Université Paris 06, UM CR18, Neuroscience Paris Seine, Paris, France
| | | | | | | | - Pascal Legendre
- INSERM, UMR-S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Paris, France; Sorbonne Universités, UPMC Université Paris 06, UM CR18, Neuroscience Paris Seine, Paris, France
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Studying Heterotypic Cell⁻Cell Interactions in the Human Brain Using Pluripotent Stem Cell Models for Neurodegeneration. Cells 2019; 8:cells8040299. [PMID: 30939814 PMCID: PMC6523455 DOI: 10.3390/cells8040299] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 03/26/2019] [Accepted: 03/29/2019] [Indexed: 02/08/2023] Open
Abstract
Human cerebral organoids derived from induced pluripotent stem cells (iPSCs) provide novel tools for recapitulating the cytoarchitecture of the human brain and for studying biological mechanisms of neurological disorders. However, the heterotypic interactions of neurovascular units, composed of neurons, pericytes (i.e., the tissue resident mesenchymal stromal cells), astrocytes, and brain microvascular endothelial cells, in brain-like tissues are less investigated. In addition, most cortical organoids lack a microglia component, the resident immune cells in the brain. Impairment of the blood-brain barrier caused by improper crosstalk between neural cells and vascular cells is associated with many neurodegenerative disorders. Mesenchymal stem cells (MSCs), with a phenotype overlapping with pericytes, have promotion effects on neurogenesis and angiogenesis, which are mainly attributed to secreted growth factors and extracellular matrices. As the innate macrophages of the central nervous system, microglia regulate neuronal activities and promote neuronal differentiation by secreting neurotrophic factors and pro-/anti-inflammatory molecules. Neuronal-microglia interactions mediated by chemokines signaling can be modulated in vitro for recapitulating microglial activities during neurodegenerative disease progression. In this review, we discussed the cellular interactions and the physiological roles of neural cells with other cell types including endothelial cells and microglia based on iPSC models. The therapeutic roles of MSCs in treating neural degeneration and pathological roles of microglia in neurodegenerative disease progression were also discussed.
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45
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DiBona VL, Zhu W, Shah MK, Rafalia A, Ben Cheikh H, Crockett DP, Zhang H. Loss of Par1b/MARK2 primes microglia during brain development and enhances their sensitivity to injury. J Neuroinflammation 2019; 16:11. [PMID: 30654821 PMCID: PMC6335724 DOI: 10.1186/s12974-018-1390-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 12/13/2018] [Indexed: 12/02/2022] Open
Abstract
Background Microglia, the resident immune cells of the brain, exhibit various morphologies that correlate with their functions under physiological and pathological conditions. In conditions such as aging and stress, microglia priming occurs, which leads to altered morphology and lower threshold for activation upon further insult. However, the molecular mechanisms that lead to microglia priming are unclear. Methods To understand the role of Par1b/MARK2 in microglia, we first expressed shRNA targeting luciferase or Par1b/MARK2 in primary microglial cells and imaged the cells using fluorescent microscopy to analyze for morphological changes. A phagocytosis assay was then used to assess functional changes. We then moved in vivo and used a Par1b/MARK2 knockout mouse model to assess for changes in microglia density, morphology, and phagocytosis using immunohistochemistry, confocal imaging, and 3D image reconstruction. Next, we used two-photon in vivo imaging in live Par1b/MARK2 deficient mice to examine microglia dynamics. In addition, a controlled-cortical impact injury was performed on wild-type and Par1b/MARK2-deficient mice and microglial response was determined by confocal imaging. Finally, to help rule out non-cell autonomous effects, we analyzed apoptosis by confocal imaging, cytokine levels by multiplex ELISA, and blood-brain barrier permeability using Evans Blue assay. Results Here, we show that loss of the cell polarity protein Par1b/MARK2 facilitates the activation of primary microglia in culture. We next found that microglia in Par1b/MARK2 deficient mice show increased density and a hypertrophic morphology. These morphological changes are accompanied with alterations in microglia functional responses including increased phagocytosis of neuronal particles early in development and decreased surveillance of the brain parenchyma, all reminiscent of a primed phenotype. Consistent with this, we found that microglia in Par1b/MARK2 deficient mice have a significantly lower threshold for activation upon injury. Conclusions Together, our studies show that loss of Par1b/MARK2 switches microglia from a surveillant to a primed state during development, resulting in an increased neuroinflammatory response to insults. Electronic supplementary material The online version of this article (10.1186/s12974-018-1390-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Victoria L DiBona
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Wenxin Zhu
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Mihir K Shah
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Aditi Rafalia
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Hajer Ben Cheikh
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - David P Crockett
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Huaye Zhang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA.
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An introduction to innate immunity in the central nervous system. ROLE OF INFLAMMATION IN ENVIRONMENTAL NEUROTOXICITY 2019. [DOI: 10.1016/bs.ant.2018.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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47
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Anderson SR, Vetter ML. Developmental roles of microglia: A window into mechanisms of disease. Dev Dyn 2019; 248:98-117. [PMID: 30444278 PMCID: PMC6328295 DOI: 10.1002/dvdy.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/21/2018] [Accepted: 10/21/2018] [Indexed: 12/12/2022] Open
Abstract
Microglia are engineers of the central nervous system (CNS) both in health and disease. In addition to the canonical immunological roles of clearing damaging entities and limiting the spread of toxicity and death, microglia remodel the CNS throughout life. While they have been extensively studied in disease and injury, due to their highly variable functions, their precise role in these contexts still remains uncertain. Over the past decade, we have greatly expanded our understanding of microglial function, including their essential homeostatic roles during development. Here, we review these developmental roles, identify parallels in disease, and speculate whether developmental mechanisms re-emerge in disease and injury. Developmental Dynamics 248:98-117, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Sarah R Anderson
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah
| | - Monica L Vetter
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah
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48
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Caspases orchestrate microglia instrumental functions. Prog Neurobiol 2018; 171:50-71. [DOI: 10.1016/j.pneurobio.2018.09.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 09/21/2018] [Accepted: 09/29/2018] [Indexed: 12/16/2022]
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Najafi AR, Crapser J, Jiang S, Ng W, Mortazavi A, West BL, Green KN. A limited capacity for microglial repopulation in the adult brain. Glia 2018; 66:2385-2396. [PMID: 30370589 PMCID: PMC6269202 DOI: 10.1002/glia.23477] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 05/04/2018] [Accepted: 05/29/2018] [Indexed: 01/21/2023]
Abstract
Microglia are the resident immune cell of the central nervous system (CNS), and serve to protect and maintain the local brain environment. Microglia are critically dependent on signaling through the colony-stimulating factor 1 receptor (CSF1R); administration of CSF1R inhibitors that cross the blood brain barrier (BBB) lead to the elimination of up to 99% of microglia, depending on CNS exposure and treatment duration. Once microglia are depleted, withdrawal of inhibitor stimulates repopulation of the entire CNS with new cells, conceivably enabling a therapeutic strategy for beneficial renewal of the entire microglial tissue. We have explored the kinetics and limits of this repopulation event and show that the rate of microglial repopulation is proportional to the extent of microglial depletion - greater depletion of microglia results in more rapid repopulation. Using a CSF1R inhibitor formulation that eliminates approximately 99% of microglia within 7 days, we subjected mice to multiple rounds of elimination (7 days' treatment) and repopulation (7 days' recovery) and found that the brain only has the capacity for a single complete repopulation event; subsequent elimination and CSF1R inhibitor withdrawal fail to repopulate the brain. However, if the recovery time between, or after, cycles is extended sufficiently then the brain can ultimately repopulate. These kinetic studies define the opportunities and possible limits of the remarkable renewal capacities of microglia.
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Affiliation(s)
- Allison R. Najafi
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
| | - Joshua Crapser
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
| | - Shan Jiang
- Department of Development and Cell Biology, University of California, Irvine, CA 92697
| | - Winnie Ng
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
| | - Ali Mortazavi
- Department of Development and Cell Biology, University of California, Irvine, CA 92697
| | | | - Kim N. Green
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697
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Konishi H, Kiyama H, Ueno M. Dual functions of microglia in the formation and refinement of neural circuits during development. Int J Dev Neurosci 2018; 77:18-25. [DOI: 10.1016/j.ijdevneu.2018.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/20/2018] [Accepted: 09/30/2018] [Indexed: 12/29/2022] Open
Affiliation(s)
- Hiroyuki Konishi
- Department of Functional Anatomy and NeuroscienceNagoya University Graduate School of MedicineNagoya466‐8550Japan
| | - Hiroshi Kiyama
- Department of Functional Anatomy and NeuroscienceNagoya University Graduate School of MedicineNagoya466‐8550Japan
| | - Masaki Ueno
- Department of System Pathology for Neurological DisordersBrain Research InstituteNiigata UniversityNiigata951‐8585Japan
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