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You Y, Chen Z, Hu WW. The role of microglia heterogeneity in synaptic plasticity and brain disorders: Will sequencing shed light on the discovery of new therapeutic targets? Pharmacol Ther 2024; 255:108606. [PMID: 38346477 DOI: 10.1016/j.pharmthera.2024.108606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/05/2024] [Accepted: 02/02/2024] [Indexed: 02/18/2024]
Abstract
Microglia play a crucial role in interacting with neuronal synapses and modulating synaptic plasticity. This function is particularly significant during postnatal development, as microglia are responsible for removing excessive synapses to prevent neurodevelopmental deficits. Dysregulation of microglial synaptic function has been well-documented in various pathological conditions, notably Alzheimer's disease and multiple sclerosis. The recent application of RNA sequencing has provided a powerful and unbiased means to decipher spatial and temporal microglial heterogeneity. By identifying microglia with varying gene expression profiles, researchers have defined multiple subgroups of microglia associated with specific pathological states, including disease-associated microglia, interferon-responsive microglia, proliferating microglia, and inflamed microglia in multiple sclerosis, among others. However, the functional roles of these distinct subgroups remain inadequately characterized. This review aims to refine our current understanding of the potential roles of heterogeneous microglia in regulating synaptic plasticity and their implications for various brain disorders, drawing from recent sequencing research and functional studies. This knowledge may aid in the identification of pathogenetic biomarkers and potential factors contributing to pathogenesis, shedding new light on the discovery of novel drug targets. The field of sequencing-based data mining is evolving toward a multi-omics approach. With advances in viral tools for precise microglial regulation and the development of brain organoid models, we are poised to elucidate the functional roles of microglial subgroups detected through sequencing analysis, ultimately identifying valuable therapeutic targets.
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Affiliation(s)
- Yi You
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Zhong Chen
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Wei-Wei Hu
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China.
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2
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Hasan R, Humphrey J, Bettencourt C, Newcombe J, Lashley T, Fratta P, Raj T. Transcriptomic analysis of frontotemporal lobar degeneration with TDP-43 pathology reveals cellular alterations across multiple brain regions. Acta Neuropathol 2022; 143:383-401. [PMID: 34961893 PMCID: PMC10725322 DOI: 10.1007/s00401-021-02399-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 12/28/2022]
Abstract
Frontotemporal lobar degeneration (FTLD) is a group of heterogeneous neurodegenerative disorders affecting the frontal and temporal lobes of the brain. Nuclear loss and cytoplasmic aggregation of the RNA-binding protein TDP-43 represents the major FTLD pathology, known as FTLD-TDP. To date, there is no effective treatment for FTLD-TDP due to an incomplete understanding of the molecular mechanisms underlying disease development. Here we compared postmortem tissue RNA-seq transcriptomes from the frontal cortex, temporal cortex, and cerebellum between 28 controls and 30 FTLD-TDP patients to profile changes in cell-type composition, gene expression and transcript usage. We observed downregulation of neuronal markers in all three regions of the brain, accompanied by upregulation of microglia, astrocytes, and oligodendrocytes, as well as endothelial cells and pericytes, suggesting shifts in both immune activation and within the vasculature. We validate our estimates of neuronal loss using neuropathological atrophy scores and show that neuronal loss in the cortex can be mainly attributed to excitatory neurons, and that increases in microglial and endothelial cell expression are highly correlated with neuronal loss. All our analyses identified a strong involvement of the cerebellum in the neurodegenerative process of FTLD-TDP. Altogether, our data provides a detailed landscape of gene expression alterations to help unravel relevant disease mechanisms in FTLD.
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Affiliation(s)
- Rahat Hasan
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Genetics and Genomic Sciences and Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Estelle and Daniel Maggin Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jack Humphrey
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Genetics and Genomic Sciences and Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Estelle and Daniel Maggin Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Conceição Bettencourt
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - Jia Newcombe
- NeuroResource, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, London, UK
| | - Tammaryn Lashley
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - Pietro Fratta
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Towfique Raj
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Genetics and Genomic Sciences and Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Estelle and Daniel Maggin Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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3
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Switching Roles: Beneficial Effects of Adipose Tissue-Derived Mesenchymal Stem Cells on Microglia and Their Implication in Neurodegenerative Diseases. Biomolecules 2022; 12:biom12020219. [PMID: 35204722 PMCID: PMC8961583 DOI: 10.3390/biom12020219] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/14/2022] [Accepted: 01/22/2022] [Indexed: 01/08/2023] Open
Abstract
Neurological disorders, including neurodegenerative diseases, are often characterized by neuroinflammation, which is largely driven by microglia, the resident immune cells of the central nervous system (CNS). Under these conditions, microglia are able to secrete neurotoxic substances, provoking neuronal cell death. However, microglia in the healthy brain carry out CNS-supporting functions. This is due to the ability of microglia to acquire different phenotypes that can play a neuroprotective role under physiological conditions or a pro-inflammatory, damaging one during disease. Therefore, therapeutic strategies focus on the downregulation of these neuroinflammatory processes and try to re-activate the neuroprotective features of microglia. Mesenchymal stem cells (MSC) of different origins have been shown to exert such effects, due to their immunomodulatory properties. In recent years, MSC derived from adipose tissue have been made the center of attention because of their easy availability and extraction methods. These cells induce a neuroprotective phenotype in microglia and downregulate neuroinflammation, resulting in an improvement of clinical symptoms in a variety of animal models for neurological pathologies, e.g., Alzheimer’s disease, traumatic brain injury and ischemic stroke. In this review, we will discuss the application of adipose tissue-derived MSC and their conditioned medium, including extracellular vesicles, in neurological disorders, their beneficial effect on microglia and the signaling pathways involved.
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4
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Yamashita H, Komine O, Fujimori-Tonou N, Yamanaka K. Comprehensive expression analysis with cell-type-specific transcriptome in ALS-linked mutant SOD1 mice: Revisiting the active role of glial cells in disease. Front Cell Neurosci 2022; 16:1045647. [PMID: 36687517 PMCID: PMC9846815 DOI: 10.3389/fncel.2022.1045647] [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: 09/15/2022] [Accepted: 12/05/2022] [Indexed: 01/06/2023] Open
Abstract
Non-cell autonomous mechanisms are involved in the pathogenesis of amyotrophic lateral sclerosis (ALS), an adult neurodegenerative disease characterized by selective motor neuron loss. While the emerging role of glial cells in ALS has been noted, the detailed cell-type-specific role of glial cells has not been clarified. Here, we examined mRNA expression changes using microarrays of the spinal cords of three distinct lines of mutant superoxide dismutase (SOD) 1 transgenic mice, an established ALS model. Our analysis used a transcriptome database of component cell types in the central nervous system (CNS), as well as SOD1 G93A cell-type transcriptomes. More than half of the differentially expressed genes (DEGs) were highly expressed in microglia, and enrichment analysis of DEGs revealed that immunological reactions were profoundly involved and some transcription factors were upregulated. Our analysis focused on DEGs that are highly expressed in each cell type, as well as chemokines, caspases, and heat shock proteins. Disease-associated microglial genes were upregulated, while homeostatic microglial genes were not, and galectin-3 (Mac2), a known activated microglial marker, was predicted to be ectopically expressed in astrocytes in mutant SOD1 mice. In mutant SOD1 mice, we developed a prediction model for the pathophysiology of different cell types related to TREM2, apolipoprotein E, and lipoproteins. Our analysis offers a viable resource to understand not only the molecular pathologies of each CNS constituent cell type, but also the cellular crosstalk between different cell types under both physiological and pathological conditions in model mice for various neurodegenerative diseases.
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Affiliation(s)
- Hirofumi Yamashita
- Department of Neurology, Japanese Red Cross Wakayama Medical Center, Wakayama, Japan.,Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Okiru Komine
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Noriko Fujimori-Tonou
- Support Unit for Bio-Material Analysis, RRD, RIKEN Center for Brain Science, Wako, Japan
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.,Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya University, Nagoya, Japan.,Institute for Glyco-Core Research (iGCORE), Nagoya University, Nagoya, Japan
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5
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Saliutina M. Opportunities of multi-omics approach for the search for new diagnostic and therapeutic targets in multiple sclerosis. Zh Nevrol Psikhiatr Im S S Korsakova 2022; 122:57-62. [DOI: 10.17116/jnevro202212205157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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6
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Bettegazzi B, Bellani S, Cattaneo S, Codazzi F, Grohovaz F, Zacchetti D. Gα13 Contributes to LPS-Induced Morphological Alterations and Affects Migration of Microglia. Mol Neurobiol 2021; 58:6397-6414. [PMID: 34529232 DOI: 10.1007/s12035-021-02553-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 08/26/2021] [Indexed: 11/24/2022]
Abstract
Microglia are the resident immune cells of the CNS that are activated in response to a variety of stimuli. This phenotypical change is aimed to maintain the local homeostasis, also by containing the insults and repair the damages. All these processes are tightly regulated and coordinated and a failure in restoring homeostasis by microglia can result in the development of neuroinflammation that can facilitate the progression of pathological conditions. Indeed, chronic microglia activation is commonly recognized as a hallmark of many neurological disorders, especially at an early stage. Many complex pathways, including cytoskeletal remodeling, are involved in the control of the microglial phenotypical and morphological changes that occur during activation. In this work, we focused on the small GTPase Gα13 and its role at the crossroad between RhoA and Rac1 signaling when microglia is exposed to pro-inflammatory stimulation. We propose the direct involvement of Gα13 in the cytoskeletal rearrangements mediated by FAK, LIMK/cofilin, and Rac1 during microglia activation. In fact, we show that Gα13 knockdown significantly inhibited LPS-induced microglial cell activation, in terms of both changes in morphology and migration, through the modulation of FAK and one of its downstream effectors, Rac1. In conclusion, we propose Gα13 as a critical factor in the regulation of morphological and functional properties of microglia during activation, which might become a target of intervention for the control of microglia inflammation.
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Affiliation(s)
- Barbara Bettegazzi
- IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy.
- Vita-Salute San Raffaele University, via Olgettina 58, 20132, Milan, Italy.
| | - Serena Bellani
- IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
| | - Stefano Cattaneo
- IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, via Olgettina 58, 20132, Milan, Italy
| | - Franca Codazzi
- IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, via Olgettina 58, 20132, Milan, Italy
| | - Fabio Grohovaz
- IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
- Vita-Salute San Raffaele University, via Olgettina 58, 20132, Milan, Italy
| | - Daniele Zacchetti
- IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy.
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7
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Brain Immunoinformatics: A Symmetrical Link between Informatics, Wet Lab and the Clinic. Symmetry (Basel) 2021. [DOI: 10.3390/sym13112168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Breakthrough advances in informatics over the last decade have thoroughly influenced the field of immunology. The intermingling of machine learning with wet lab applications and clinical results has hatched the newly defined immunoinformatics society. Immunoinformatics of the central neural system, referred to as neuroimmunoinformatics (NII), investigates symmetrical and asymmetrical interactions of the brain-immune interface. This interdisciplinary overview on NII is addressed to bioscientists and computer scientists. We delineate the dominating trajectories and field-shaping achievements and elaborate on future directions using bridging language and terminology. Computation, varying from linear modeling to complex deep learning approaches, fuels neuroimmunology through three core directions. Firstly, by providing big-data analysis software for high-throughput methods such as next-generation sequencing and genome-wide association studies. Secondly, by designing models for the prediction of protein morphology, functions, and symmetrical and asymmetrical protein–protein interactions. Finally, NII boosts the output of quantitative pathology by enabling the automatization of tedious processes such as cell counting, tracing, and arbor analysis. The new classification of microglia, the brain’s innate immune cells, was an NII achievement. Deep sequencing classifies microglia in “sensotypes” to accurately describe the versatility of immune responses to physiological and pathological challenges, as well as to experimental conditions such as xenografting and organoids. NII approaches complex tasks in the brain-immune interface, recognizes patterns and allows for hypothesis-free predictions with ultimate targeted individualized treatment strategies, and personalizes disease prognosis and treatment response.
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8
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Butler CA, Popescu AS, Kitchener EJA, Allendorf DH, Puigdellívol M, Brown GC. Microglial phagocytosis of neurons in neurodegeneration, and its regulation. J Neurochem 2021; 158:621-639. [PMID: 33608912 DOI: 10.1111/jnc.15327] [Citation(s) in RCA: 118] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 01/13/2021] [Accepted: 02/10/2021] [Indexed: 02/06/2023]
Abstract
There is growing evidence that excessive microglial phagocytosis of neurons and synapses contributes to multiple brain pathologies. RNA-seq and genome-wide association (GWAS) studies have linked multiple phagocytic genes to neurodegenerative diseases, and knock-out of phagocytic genes has been found to protect against neurodegeneration in animal models, suggesting that excessive microglial phagocytosis contributes to neurodegeneration. Here, we review recent evidence that microglial phagocytosis of live neurons and synapses causes neurodegeneration in animal models of Alzheimer's disease and other tauopathies, Parkinson's disease, frontotemporal dementias, multiple sclerosis, retinal degeneration and neurodegeneration induced by ischaemia, infection or ageing. We also review factors regulating microglial phagocytosis of neurons, including: nucleotides, frackalkine, phosphatidylserine, calreticulin, UDP, CD47, sialylation, complement, galectin-3, Apolipoprotein E, phagocytic receptors, Siglec receptors, cytokines, microglial epigenetics and expression profile. Some of these factors may be potential treatment targets to prevent neurodegeneration mediated by excessive microglial phagocytosis of live neurons and synapses.
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Affiliation(s)
- Claire A Butler
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Alma S Popescu
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | | | - Mar Puigdellívol
- Department of Biochemistry, University of Cambridge, Cambridge, UK.,Departament de Biomedicina, Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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9
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Pembroke WG, Hartl CL, Geschwind DH. Evolutionary conservation and divergence of the human brain transcriptome. Genome Biol 2021; 22:52. [PMID: 33514394 PMCID: PMC7844938 DOI: 10.1186/s13059-020-02257-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 12/20/2020] [Indexed: 12/20/2022] Open
Abstract
Background Mouse models have allowed for the direct interrogation of genetic effects on molecular, physiological, and behavioral brain phenotypes. However, it is unknown to what extent neurological or psychiatric traits may be human- or primate-specific and therefore which components can be faithfully recapitulated in mouse models. Results We compare conservation of co-expression in 116 independent data sets derived from human, mouse, and non-human primate representing more than 15,000 total samples. We observe greater changes occurring on the human lineage than mouse, and substantial regional variation that highlights cerebral cortex as the most diverged region. Glia, notably microglia, astrocytes, and oligodendrocytes are the most divergent cell type, three times more on average than neurons. We show that cis-regulatory sequence divergence explains a significant fraction of co-expression divergence. Moreover, protein coding sequence constraint parallels co-expression conservation, such that genes with loss of function intolerance are enriched in neuronal, rather than glial modules. We identify dozens of human neuropsychiatric and neurodegenerative disease risk genes, such as COMT, PSEN-1, LRRK2, SHANK3, and SNCA, with highly divergent co-expression between mouse and human and show that 3D human brain organoids recapitulate in vivo co-expression modules representing several human cell types. Conclusions We identify robust co-expression modules reflecting whole-brain and regional patterns of gene expression. Compared with those that represent basic metabolic processes, cell-type-specific modules, most prominently glial modules, are the most divergent between species. These data and analyses serve as a foundational resource to guide human disease modeling and its interpretation. Supplementary Information The online version contains supplementary material available at 10.1186/s13059-020-02257-z.
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Affiliation(s)
- William G Pembroke
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Christopher L Hartl
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Daniel H Geschwind
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA. .,Center for Autism Research and Treatment, Semel Institute, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA. .,Department of Human Genetics, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.
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10
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Woo YH, Martinez LR. Cryptococcus neoformans-astrocyte interactions: effect on fungal blood brain barrier disruption, brain invasion, and meningitis progression. Crit Rev Microbiol 2021; 47:206-223. [PMID: 33476528 DOI: 10.1080/1040841x.2020.1869178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cryptococcus neoformans is an opportunistic, neurotropic, and encapsulated fungus that causes life-threatening cryptococcal meningitis (CM), especially in regions of the world where AIDS is endemic. The polysaccharide capsule of C. neoformans is the fungus major virulent factor, being copiously released during infection and causing immunosuppressive defects in the host. Although the capsular material is commonly associated with reactive astrocytes in fatal CM, little is known about the molecular and cellular interactions among astroglia and C. neoformans. As astrocytes also make up the neurovascular unit at the blood-brain barrier (BBB), which C. neoformans must transverse to colonize the central nervous system and cause CM; these cells may play a significant regulatory role in the prevention and progression of infection. For example, astrocytes are implicated in neurological disease including the regulation of cerebral intracranial pressure, immune function, and water homeostasis. Hence, in this review, we provide a general overview of astroglia biology and discuss the current knowledge on C. neoformans-astrocyte interactions including their involvement in the development of CM. This "gliocentric view" of cerebral cryptococcosis suggests that therapeutic interventions particularly targeting at preserving the neuroprotective function of astrocytes may be used in preventing and managing C. neoformans BBB transmigration, brain invasion, colonization, and meningitis.
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Affiliation(s)
- Yeon Hwa Woo
- Department of Metallurgical, Materials and Biomedical Engineering, College of Engineering, The University of Texas at El Paso, El Paso, TX, USA
| | - Luis R Martinez
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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11
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Miedema A, Wijering MHC, Eggen BJL, Kooistra SM. High-Resolution Transcriptomic and Proteomic Profiling of Heterogeneity of Brain-Derived Microglia in Multiple Sclerosis. Front Mol Neurosci 2020; 13:583811. [PMID: 33192299 PMCID: PMC7654237 DOI: 10.3389/fnmol.2020.583811] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022] Open
Abstract
Microglia are important for central nervous system (CNS) homeostasis and first to respond to tissue damage and perturbations. Microglia are heterogeneous cells; in case of pathology, microglia adopt a range of phenotypes with altered functions. However, how these different microglia subtypes are implicated in CNS disease is largely unresolved. Multiple sclerosis (MS) is a chronic demyelinating disease of the CNS, characterized by inflammation and axonal degeneration, ultimately leading to neurological decline. One way microglia are implicated in MS is through stimulation of remyelination. They facilitate efficient remyelination by phagocytosis of myelin debris. In addition, microglia recruit oligodendrocyte precursor cells (OPCs) to demyelinated areas and stimulate remyelination. The development of high-resolution technologies to profile individual cells has greatly contributed to our understanding of microglia heterogeneity and function under normal and pathological conditions. Gene expression profiling technologies have evolved from whole tissue RNA sequencing toward single-cell or nucleus sequencing. Single microglia proteomic profiles are also increasingly generated, offering another layer of high-resolution data. Here, we will review recent studies that have employed these technologies in the context of MS and their respective advantages and disadvantages. Moreover, recent developments that allow for (single) cell profiling while retaining spatial information and tissue context will be discussed.
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Affiliation(s)
- Anneke Miedema
- Section Molecular Neurobiology, Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Marion H C Wijering
- Section Molecular Neurobiology, Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Bart J L Eggen
- Section Molecular Neurobiology, Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Susanne M Kooistra
- Section Molecular Neurobiology, Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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12
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Abstract
Microglia are the major immune cells in the central nervous system and play a key role in the normal function of the brain. Microglia exhibit functional diversity, and they control the inflammation in central nervous system through releasing inflammatory cytokine, clearing apoptotic cells via phagocytosis, regulating synaptic plasticity and the formation of neural network by synapse pruning. Recent studies have strongly indicated that the microglial dysfunction is associated with a variety of neuropsychiatric diseases such as depression, which have been termed as "microgliopathy". The emergency of advanced technologies and tools has enabled us to comprehensively understand the role of microglia in physiology and pathology, and growing studies have targetted microglia to explore the treatment of neuropsychiatric diseases. Here, we describe the key progress of microglia research, and review the recent developments in the understanding of the role of microglia in physiology and etiology of depression.
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13
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Gerrits E, Heng Y, Boddeke EWGM, Eggen BJL. Transcriptional profiling of microglia; current state of the art and future perspectives. Glia 2019; 68:740-755. [PMID: 31846124 PMCID: PMC7064956 DOI: 10.1002/glia.23767] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/11/2019] [Accepted: 12/03/2019] [Indexed: 12/14/2022]
Abstract
Microglia are the tissue macrophages of the central nervous system (CNS) and the first to respond to CNS dysfunction and disease. Gene expression profiling of microglia during development, under homeostatic conditions, and in the diseased CNS provided insight in microglia functions and changes thereof. Single-cell sequencing studies further contributed to our understanding of microglia heterogeneity in relation to age, sex, and CNS disease. Recently, single nucleus gene expression profiling was performed on (frozen) CNS tissue. Transcriptomic profiling of CNS tissues by (single) nucleus RNA-sequencing has the advantage that it can be applied to archived and well-stratified frozen specimens. Here, we give an overview of the significant advances recently made in microglia transcriptional profiling. In addition, we present matched cellular and nuclear microglia RNA-seq datasets we generated from mouse and human CNS tissue to compare cellular versus nuclear transcriptomes from fresh and frozen samples. We demonstrate that microglia can be similarly profiled with cell and nucleus profiling, and importantly also with nuclei isolated from frozen tissue. Nuclear microglia transcriptomes are a reliable proxy for cellular transcriptomes. Importantly, lipopolysaccharide-induced changes in gene expression were conserved in the nuclear transcriptome. In addition, heterogeneity in microglia observed in fresh samples was similarly detected in frozen nuclei of the same donor. Together, these results show that microglia nuclear RNAs obtained from frozen CNS tissue are a reliable proxy for microglia gene expression and cellular heterogeneity and may prove an effective strategy to study of the role of microglia in neuropathology.
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Affiliation(s)
- Emma Gerrits
- Department of Biomedical Sciences of Cells & Systems, Section Molecular Neurobiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Yang Heng
- Department of Biomedical Sciences of Cells & Systems, Section Molecular Neurobiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Erik W G M Boddeke
- Department of Biomedical Sciences of Cells & Systems, Section Molecular Neurobiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Bart J L Eggen
- Department of Biomedical Sciences of Cells & Systems, Section Molecular Neurobiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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14
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Reuschlein AK, Jakobsen E, Mertz C, Bak LK. Aspects of astrocytic cAMP signaling with an emphasis on the putative power of compartmentalized signals in health and disease. Glia 2019; 67:1625-1636. [PMID: 31033018 DOI: 10.1002/glia.23622] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/29/2019] [Accepted: 03/29/2019] [Indexed: 12/17/2022]
Abstract
This review discusses aspects of known and putative compartmentalized 3',5'-cyclic adenosine monophosphate (cAMP) signaling in astrocytes, a cell type that has turned out to be a key player in brain physiology and pathology. cAMP has attracted less attention than Ca2+ in recent years, but could turn out to rival Ca2+ in its potential to drive cellular functions and responses to intra- and extracellular cues. Further, Ca2+ and cAMP are known to engage in extensive crosstalk and cAMP signals often take place within subcellular compartments revolving around multi-protein signaling complexes; however, we know surprisingly little about this in astrocytes. Here, we review aspects of astrocytic cAMP signaling, provide arguments for an increased interest in this subject, suggest possible future research directions within the field, and discuss putative drug targets.
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Affiliation(s)
- Ann-Kathrin Reuschlein
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emil Jakobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christoffer Mertz
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lasse K Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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15
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Fernandez CG, Hamby ME, McReynolds ML, Ray WJ. The Role of APOE4 in Disrupting the Homeostatic Functions of Astrocytes and Microglia in Aging and Alzheimer's Disease. Front Aging Neurosci 2019; 11:14. [PMID: 30804776 PMCID: PMC6378415 DOI: 10.3389/fnagi.2019.00014] [Citation(s) in RCA: 154] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/16/2019] [Indexed: 12/20/2022] Open
Abstract
APOE4 is the greatest genetic risk factor for late-onset Alzheimer’s disease (AD), increasing the risk of developing the disease by 3-fold in the 14% of the population that are carriers. Despite 25 years of research, the exact mechanisms underlying how APOE4 contributes to AD pathogenesis remain incompletely defined. APOE in the brain is primarily expressed by astrocytes and microglia, cell types that are now widely appreciated to play key roles in the pathogenesis of AD; thus, a picture is emerging wherein APOE4 disrupts normal glial cell biology, intersecting with changes that occur during normal aging to ultimately cause neurodegeneration and cognitive dysfunction. This review article will summarize how APOE4 alters specific pathways in astrocytes and microglia in the context of AD and the aging brain. APOE itself, as a secreted lipoprotein without enzymatic activity, may prove challenging to directly target therapeutically in the classical sense. Therefore, a deeper understanding of the underlying pathways responsible for APOE4 toxicity is needed so that more tractable pathways and drug targets can be identified to reduce APOE4-mediated disease risk.
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Affiliation(s)
- Celia G Fernandez
- The Neurodegeneration Consortium, Institute of Applied Cancer Science (IACS), The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Mary E Hamby
- The Neurodegeneration Consortium, Institute of Applied Cancer Science (IACS), The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Morgan L McReynolds
- The Neurodegeneration Consortium, Institute of Applied Cancer Science (IACS), The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - William J Ray
- The Neurodegeneration Consortium, Institute of Applied Cancer Science (IACS), The University of Texas MD Anderson Cancer Center, Houston, TX, United States
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16
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Calovi S, Mut-Arbona P, Sperlágh B. Microglia and the Purinergic Signaling System. Neuroscience 2018; 405:137-147. [PMID: 30582977 DOI: 10.1016/j.neuroscience.2018.12.021] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 02/07/2023]
Abstract
Microglia are the main resident immune-competent cell type of the central nervous system (CNS); these cells are highly sensitive to subtle changes in the chemical environment of the brain. Microglia are activated during diverse conditions, such as apoptosis, trauma, inflammation, and infection. The specific activities of microglia result from the confluence of environmental stimuli and the cellular state. It is likely that several signaling systems with different biological functions operate in competition and/or synergy, thus regulating similar microglial behaviors. The purinergic system is one of the fundamental signaling systems that establish microglial behavior in a wide spectrum of conditions. Adenosine tri-phosphate (ATP) belongs to the purinergic signaling system, which includes P2X, P2Y, and P1 receptors, as well as other proteins participating in ATP secretion and extracellular ATP degradation, and molecules that recognize purines as a ligand. In this review, we focus on the latest pre-clinical and basic purinergic system and microglial research, with particular attention to data collected in vivo and ex vivo. This chapter is divided into sections related to microglial ATP release, ATP degradation, and ATP-related actions mediated by P2X and P2Y receptor activation.
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Affiliation(s)
- Stefano Calovi
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; János Szentágothai School of Neurosciences, Semmelweis University School of PhD Studies, Budapest, Hungary
| | - Paula Mut-Arbona
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; János Szentágothai School of Neurosciences, Semmelweis University School of PhD Studies, Budapest, Hungary
| | - Beáta Sperlágh
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
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17
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Wang H, Li Y, Ryder JW, Hole JT, Ebert PJ, Airey DC, Qian HR, Logsdon B, Fisher A, Ahmed Z, Murray TK, Cavallini A, Bose S, Eastwood BJ, Collier DA, Dage JL, Miller BB, Merchant KM, O'Neill MJ, Demattos RB. Genome-wide RNAseq study of the molecular mechanisms underlying microglia activation in response to pathological tau perturbation in the rTg4510 tau transgenic animal model. Mol Neurodegener 2018; 13:65. [PMID: 30558641 PMCID: PMC6296031 DOI: 10.1186/s13024-018-0296-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/28/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Activation of microglia, the resident immune cells of the central nervous system, is a prominent pathological hallmark of Alzheimer's disease (AD). However, the gene expression changes underlying microglia activation in response to tau pathology remain elusive. Furthermore, it is not clear how murine gene expression changes relate to human gene expression networks. METHODS Microglia cells were isolated from rTg4510 tau transgenic mice and gene expression was profiled using RNA sequencing. Four age groups of mice (2-, 4-, 6-, and 8-months) were analyzed to capture longitudinal gene expression changes that correspond to varying levels of pathology, from minimal tau accumulation to massive neuronal loss. Statistical and system biology approaches were used to analyze the genes and pathways that underlie microglia activation. Differentially expressed genes were compared to human brain co-expression networks. RESULTS Statistical analysis of RNAseq data indicated that more than 4000 genes were differentially expressed in rTg4510 microglia compared to wild type microglia, with the majority of gene expression changes occurring between 2- and 4-months of age. These genes belong to four major clusters based on their temporal expression pattern. Genes involved in innate immunity were continuously up-regulated, whereas genes involved in the glutamatergic synapse were down-regulated. Up-regulated innate inflammatory pathways included NF-κB signaling, cytokine-cytokine receptor interaction, lysosome, oxidative phosphorylation, and phagosome. NF-κB and cytokine signaling were among the earliest pathways activated, likely driven by the RELA, STAT1 and STAT6 transcription factors. The expression of many AD associated genes such as APOE and TREM2 was also altered in rTg4510 microglia cells. Differentially expressed genes in rTg4510 microglia were enriched in human neurodegenerative disease associated pathways, including Alzheimer's, Parkinson's, and Huntington's diseases, and highly overlapped with the microglia and endothelial modules of human brain transcriptional co-expression networks. CONCLUSION This study revealed temporal transcriptome alterations in microglia cells in response to pathological tau perturbation and provides insight into the molecular changes underlying microglia activation during tau mediated neurodegeneration.
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Affiliation(s)
- Hong Wang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA.
| | - Yupeng Li
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - John W Ryder
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - Justin T Hole
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - Philip J Ebert
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - David C Airey
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - Hui-Rong Qian
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | | | - Alice Fisher
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Zeshan Ahmed
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Tracey K Murray
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Annalisa Cavallini
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Suchira Bose
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Brian J Eastwood
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - David A Collier
- Eli Lilly and Company Limited, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Jeffrey L Dage
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - Bradley B Miller
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | | | - Michael J O'Neill
- Present address: AbbVie Deutschland GmbH & Co. K.G, Ludwigshafen, Germany
| | - Ronald B Demattos
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
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18
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Guttenplan KA, Liddelow SA. Astrocytes and microglia: Models and tools. J Exp Med 2018; 216:71-83. [PMID: 30541903 PMCID: PMC6314517 DOI: 10.1084/jem.20180200] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/16/2018] [Accepted: 11/26/2018] [Indexed: 01/05/2023] Open
Abstract
An amazing array of tools both old and new are available to investigate the function of astrocytes and microglia. Guttenplan and Liddelow discuss tools available to study the physiology and pathophysiology of these cells both in vivo and in culture systems. Glial cells serve as fundamental regulators of the central nervous system in development, homeostasis, and disease. Discoveries into the function of these cells have fueled excitement in glial research, with enthusiastic researchers addressing fundamental questions about glial biology and producing new scientific tools for the community. Here, we outline the pros and cons of in vivo and in vitro techniques to study astrocytes and microglia with the goal of helping researchers quickly identify the best approach for a given research question in the context of glial biology. It is truly a great time to be a glial biologist.
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Affiliation(s)
| | - Shane A Liddelow
- Neuroscience Institute, NYU Langone Medical Center, New York, NY.,Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY.,Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia
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19
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Dubbelaar ML, Kracht L, Eggen BJL, Boddeke EWGM. The Kaleidoscope of Microglial Phenotypes. Front Immunol 2018; 9:1753. [PMID: 30108586 PMCID: PMC6079257 DOI: 10.3389/fimmu.2018.01753] [Citation(s) in RCA: 192] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 07/16/2018] [Indexed: 12/11/2022] Open
Abstract
Gene expression analyses of microglia, the tissue-resident macrophages of the central nervous system (CNS), led to the identification of homeostatic as well as neurological disease-specific gene signatures of microglial phenotypes. Upon alterations in the neural microenvironment, either caused by local insults from within the CNS (during neurodegenerative diseases) or by macroenvironmental incidents, such as social stress, microglia can switch phenotypes-generally referred to as "microglial activation." The interplay between the microenvironment and its influence on microglial phenotypes, regulated by (epi)genetic mechanisms, can be imagined as the different colorful crystal formations (microglial phenotypes) that change upon rotation (microenvironmental changes) of a kaleidoscope. In this review, we will discuss microglial phenotypes in relation to neurodevelopment, homeostasis, in vitro conditions, aging, and neurodegenerative diseases based on transcriptome studies. By overlaying these disease-specific microglial signatures, recent publications have identified a specific set of genes that is differentially expressed in all investigated diseases, called a microglial core gene signature with multiple diseases. We will conclude this review with a discussion about the complexity of this microglial core gene signature associated with multiple diseases.
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Affiliation(s)
- Marissa L Dubbelaar
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Laura Kracht
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Bart J L Eggen
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Erik W G M Boddeke
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
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20
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Zhao X, Eyo UB, Murguan M, Wu LJ. Microglial interactions with the neurovascular system in physiology and pathology. Dev Neurobiol 2018; 78:604-617. [PMID: 29318762 PMCID: PMC5980686 DOI: 10.1002/dneu.22576] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 01/01/2018] [Accepted: 01/06/2018] [Indexed: 01/11/2023]
Abstract
Microglia as immune cells of the central nervous system (CNS) play significant roles not only in pathology but also in physiology, such as shaping of the CNS during development and its proper maintenance in maturity. Emerging research is showing a close association between microglia and the neurovasculature that is critical for brain energy supply. In this review, we summarize the current literature on microglial interaction with the vascular system in the normal and diseased brain. First, we highlight data that indicate interesting potential involvement of microglia in developmental angiogenesis. Then we discuss the evidence for microglial participation with the vasculature in neuropathologies from brain tumors to acute injuries such as ischemic stroke to chronic neurodegenerative conditions. We conclude by suggesting future areas of research to advance the field in light of current technical progress and outstanding questions. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 604-617, 2018.
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Affiliation(s)
- Xiaoliang Zhao
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
| | - Ukpong B. Eyo
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
| | - Madhuvika Murguan
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
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21
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Bak LK, Walls AB, Schousboe A, Waagepetersen HS. Astrocytic glycogen metabolism in the healthy and diseased brain. J Biol Chem 2018; 293:7108-7116. [PMID: 29572349 DOI: 10.1074/jbc.r117.803239] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The brain contains a fairly low amount of glycogen, mostly located in astrocytes, a fact that has prompted the suggestion that glycogen does not have a significant physiological role in the brain. However, glycogen metabolism in astrocytes is essential for several key physiological processes and is adversely affected in disease. For instance, diminished ability to break down glycogen impinges on learning, and epilepsy, Alzheimer's disease, and type 2 diabetes are all associated with abnormal astrocyte glycogen metabolism. Glycogen metabolism supports astrocytic K+ and neurotransmitter glutamate uptake and subsequent glutamine synthesis-three fundamental steps in excitatory signaling at most brain synapses. Thus, there is abundant evidence for a key role of glycogen in brain function. Here, we summarize the physiological brain functions that depend on glycogen, discuss glycogen metabolism in disease, and investigate how glycogen breakdown is regulated at the cellular and molecular levels.
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Affiliation(s)
- Lasse K Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark.
| | - Anne B Walls
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
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22
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Wilhelmsson U, Andersson D, de Pablo Y, Pekny R, Ståhlberg A, Mulder J, Mitsios N, Hortobágyi T, Pekny M, Pekna M. Injury Leads to the Appearance of Cells with Characteristics of Both Microglia and Astrocytes in Mouse and Human Brain. Cereb Cortex 2018; 27:3360-3377. [PMID: 28398520 DOI: 10.1093/cercor/bhx069] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Indexed: 12/21/2022] Open
Abstract
Microglia and astrocytes have been considered until now as cells with very distinct identities. Here, we assessed the heterogeneity within microglia/monocyte cell population in mouse hippocampus and determined their response to injury, by using single-cell gene expression profiling of cells isolated from uninjured and deafferented hippocampus. We found that in individual cells, microglial markers Cx3cr1, Aif1, Itgam, and Cd68 were co-expressed. Interestingly, injury led to the co-expression of the astrocyte marker Gfap in a subpopulation of Cx3cr1-expressing cells from both the injured and contralesional hippocampus. Cells co-expressing astrocyte and microglia markers were also detected in the in vitro LPS activation/injury model and in sections from human brain affected by stroke, Alzheimer's disease, and Lewy body dementia. Our findings indicate that injury and chronic neurodegeneration lead to the appearance of cells that share molecular characteristics of both microglia and astrocytes, 2 cell types with distinct embryologic origin and function.
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Affiliation(s)
- Ulrika Wilhelmsson
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Daniel Andersson
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Yolanda de Pablo
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Roy Pekny
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Anders Ståhlberg
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Jan Mulder
- Science for Life Laboratory, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Nicholas Mitsios
- Science for Life Laboratory, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Tibor Hortobágyi
- Division of Neuropathology, Institute of Pathology, Faculty of Medicine, University of Debrecen, Hungary.,Department of Old Age Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
| | - Milos Pekny
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden.,Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Hunter Medical Research Institute, University of Newcastle, New South Wales, Australia
| | - Marcela Pekna
- Laboratory of Regenerative Neuroimmunology, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden.,Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Hunter Medical Research Institute, University of Newcastle, New South Wales, Australia
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23
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Cao Y, Zhu J, Jia P, Zhao Z. scRNASeqDB: A Database for RNA-Seq Based Gene Expression Profiles in Human Single Cells. Genes (Basel) 2017; 8:genes8120368. [PMID: 29206167 PMCID: PMC5748686 DOI: 10.3390/genes8120368] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 12/14/2022] Open
Abstract
Single-cell RNA sequencing (scRNA-Seq) is rapidly becoming a powerful tool for high-throughput transcriptomic analysis of cell states and dynamics at the single cell level. Both the number and quality of scRNA-Seq datasets have dramatically increased recently. A database that can comprehensively collect, curate, and compare expression features of scRNA-Seq data in humans has not yet been built. Here, we present scRNASeqDB, a database that includes almost all the currently available human single cell transcriptome datasets (n = 38) covering 200 human cell lines or cell types and 13,440 samples. Our online web interface allows users to rank the expression profiles of the genes of interest across different cell types. It also provides tools to query and visualize data, including Gene Ontology and pathway annotations for differentially expressed genes between cell types or groups. The scRNASeqDB is a useful resource for single cell transcriptional studies. This database is publicly available at https://bioinfo.uth.edu/scrnaseqdb/.
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Affiliation(s)
- Yuan Cao
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| | - Junjie Zhu
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Peilin Jia
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| | - Zhongming Zhao
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
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24
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Mancarci BO, Toker L, Tripathy SJ, Li B, Rocco B, Sibille E, Pavlidis P. Cross-Laboratory Analysis of Brain Cell Type Transcriptomes with Applications to Interpretation of Bulk Tissue Data. eNeuro 2017; 4:ENEURO.0212-17.2017. [PMID: 29204516 PMCID: PMC5707795 DOI: 10.1523/eneuro.0212-17.2017] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/25/2017] [Accepted: 10/31/2017] [Indexed: 12/13/2022] Open
Abstract
Establishing the molecular diversity of cell types is crucial for the study of the nervous system. We compiled a cross-laboratory database of mouse brain cell type-specific transcriptomes from 36 major cell types from across the mammalian brain using rigorously curated published data from pooled cell type microarray and single-cell RNA-sequencing (RNA-seq) studies. We used these data to identify cell type-specific marker genes, discovering a substantial number of novel markers, many of which we validated using computational and experimental approaches. We further demonstrate that summarized expression of marker gene sets (MGSs) in bulk tissue data can be used to estimate the relative cell type abundance across samples. To facilitate use of this expanding resource, we provide a user-friendly web interface at www.neuroexpresso.org.
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Affiliation(s)
- B. Ogan Mancarci
- Graduate Program in Bioinformatics, University of British Columbia, Vancouver V6T 1Z4, Canada
- Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Lilah Toker
- Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Shreejoy J. Tripathy
- Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Brenna Li
- Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Brad Rocco
- Campbell Family Mental Health Research Institute of CAMH
- Department of Psychiatry and the Department of Pharmacology and Toxicology, University of Toronto, Vancouver M5S 1A8, Canada
| | - Etienne Sibille
- Campbell Family Mental Health Research Institute of CAMH
- Department of Psychiatry and the Department of Pharmacology and Toxicology, University of Toronto, Vancouver M5S 1A8, Canada
| | - Paul Pavlidis
- Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, Canada
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25
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Wlodarczyk A, Holtman IR, Krueger M, Yogev N, Bruttger J, Khorooshi R, Benmamar-Badel A, de Boer-Bergsma JJ, Martin NA, Karram K, Kramer I, Boddeke EW, Waisman A, Eggen BJ, Owens T. A novel microglial subset plays a key role in myelinogenesis in developing brain. EMBO J 2017; 36:3292-3308. [PMID: 28963396 PMCID: PMC5686552 DOI: 10.15252/embj.201696056] [Citation(s) in RCA: 316] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 08/30/2017] [Accepted: 08/31/2017] [Indexed: 02/06/2023] Open
Abstract
Microglia are resident macrophages of the central nervous system that contribute to homeostasis and neuroinflammation. Although known to play an important role in brain development, their exact function has not been fully described. Here, we show that in contrast to healthy adult and inflammation‐activated cells, neonatal microglia show a unique myelinogenic and neurogenic phenotype. A CD11c+ microglial subset that predominates in primary myelinating areas of the developing brain expresses genes for neuronal and glial survival, migration, and differentiation. These cells are the major source of insulin‐like growth factor 1, and its selective depletion from CD11c+ microglia leads to impairment of primary myelination. CD11c‐targeted toxin regimens induced a selective transcriptional response in neonates, distinct from adult microglia. CD11c+ microglia are also found in clusters of repopulating microglia after experimental ablation and in neuroinflammation in adult mice, but despite some similarities, they do not recapitulate neonatal microglial characteristics. We therefore identify a unique phenotype of neonatal microglia that deliver signals necessary for myelination and neurogenesis.
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Affiliation(s)
- Agnieszka Wlodarczyk
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Inge R Holtman
- Department of Neuroscience, Medical Physiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Martin Krueger
- Institute for Anatomy, University of Leipzig, Leipzig, Germany
| | - Nir Yogev
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Julia Bruttger
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Reza Khorooshi
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Anouk Benmamar-Badel
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Biology, Ecole Normale Supérieure de Lyon, University of Lyon, Lyon, France
| | - Jelkje J de Boer-Bergsma
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Nellie A Martin
- Department of Neurology, Institute of Clinical Research, Odense University Hospital, Odense, Denmark
| | - Khalad Karram
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Isabella Kramer
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Erik Wgm Boddeke
- Department of Neuroscience, Medical Physiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ari Waisman
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Bart Jl Eggen
- Department of Neuroscience, Medical Physiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Trevor Owens
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
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26
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E Hirbec H, Noristani HN, Perrin FE. Microglia Responses in Acute and Chronic Neurological Diseases: What Microglia-Specific Transcriptomic Studies Taught (and did Not Teach) Us. Front Aging Neurosci 2017; 9:227. [PMID: 28785215 PMCID: PMC5519576 DOI: 10.3389/fnagi.2017.00227] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/04/2017] [Indexed: 12/11/2022] Open
Abstract
Over the last decade, microglia have been acknowledged to be key players in central nervous system (CNS) under both physiological and pathological conditions. They constantly survey the CNS environment and as immune cells, in pathological contexts, they provide the first host defense and orchestrate the immune response. It is well recognized that under pathological conditions microglia have both sequential and simultaneous, beneficial and detrimental effects. Cell-specific transcriptomics recently became popular in Neuroscience field allowing concurrent monitoring of the expression of numerous genes in a given cell population. Moreover, by comparing two or more conditions, these approaches permit to unbiasedly identify deregulated genes and pathways. A growing number of studies have thus investigated microglial transcriptome remodeling over the course of neuropathological conditions and highlighted the molecular diversity of microglial response to different diseases. In the present work, we restrict our review to microglia obtained directly from in vivo samples and not cell culture, and to studies using whole-genome strategies. We first critically review the different methods developed to decipher microglia transcriptome. In particular, we compare advantages and drawbacks of flow cytometry and laser microdissection to isolate pure microglia population as well as identification of deregulated microglial genes obtained via RNA sequencing (RNA-Seq) vs. microarrays approaches. Second, we summarize insights obtained from microglia transcriptomes in traumatic brain and spinal cord injuries, pain and more chronic neurological conditions including Amyotrophic lateral sclerosis (ALS), Alzheimer disease (AD) and Multiple sclerosis (MS). Transcriptomic responses of microglia in other non-neurodegenerative CNS disorders such as gliomas and sepsis are also addressed. Third, we present a comparison of the most activated pathways in each neuropathological condition using Gene ontology (GO) classification and highlight the diversity of microglia response to insults focusing on their pro- and anti-inflammatory signatures. Finally, we discuss the potential of the latest technological advances, in particular, single cell RNA-Seq to unravel the individual microglial response diversity in neuropathological contexts.
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Affiliation(s)
- Hélène E Hirbec
- Institute for Functional Genomics, CNRS UMR5203, INSERM U1191, University of MontpellierMontpellier, France.,Laboratory of Excellence in Ion Channel Science and Therapeutics (LabEx ICST)Montpellier, France
| | - Harun N Noristani
- University of Montpellier, INSERM U1198Montpellier, France.,École Pratique des Hautes Études (EPHE)Paris, France
| | - Florence E Perrin
- University of Montpellier, INSERM U1198Montpellier, France.,École Pratique des Hautes Études (EPHE)Paris, France
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27
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A polarizing question: do M1 and M2 microglia exist? Nat Neurosci 2017; 19:987-91. [PMID: 27459405 DOI: 10.1038/nn.4338] [Citation(s) in RCA: 1062] [Impact Index Per Article: 151.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/14/2016] [Indexed: 12/12/2022]
Abstract
Microglial research has entered a fertile, dynamic phase characterized by novel technologies including two-photon imaging, whole-genome transcriptomic and epigenomic analysis with complementary bioinformatics, unbiased proteomics, cytometry by time of flight (CyTOF; Fluidigm) cytometry, and complex high-content experimental models including slice culture and zebrafish. Against this vivid background of newly emerging data, investigators will encounter in the microglial research literature a body of published work using the terminology of macrophage polarization, most commonly into the M1 and M2 phenotypes. It is the assertion of this opinion piece that microglial polarization has not been established by research findings. Rather, the adoption of this schema was undertaken in an attempt to simplify data interpretation at a time when the ontogeny and functional significance of microglia had not yet been characterized. Now, terminology suggesting established meaningful pathways of microglial polarization hinders rather than aids research progress and should be discarded.
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28
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Kudriaeva A, Galatenko VV, Maltseva DV, Khaustova NA, Kuzina E, Tonevitsky AG, Gabibov A, Belogurov A. The Transcriptome of Type I Murine Astrocytes under Interferon-Gamma Exposure and Remyelination Stimulus. Molecules 2017; 22:molecules22050808. [PMID: 28505143 PMCID: PMC6153759 DOI: 10.3390/molecules22050808] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/30/2017] [Accepted: 05/11/2017] [Indexed: 02/04/2023] Open
Abstract
Astrocytes are considered to be an important contributor to central nervous system (CNS) disorders, particularly multiple sclerosis. The transcriptome of these cells is greatly affected by cytokines released by lymphocytes, penetrating the blood–brain barrier—in particular, the classical pro-inflammatory cytokine interferon-gamma (IFNγ). We report here the transcriptomal profiling of astrocytes treated using IFNγ and benztropine, a putative remyelinization agent. Our findings indicate that the expression of genes involved in antigen processing and presentation in astrocytes are significantly upregulated upon IFNγ exposure, emphasizing the critical role of this cytokine in the redirection of immune response towards self-antigens. Data reported herein support previous observations that the IFNγ-induced JAK-STAT signaling pathway may be regarded as a valuable target for pharmaceutical interventions.
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Affiliation(s)
- Anna Kudriaeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia.
| | - Vladimir V Galatenko
- Department of Mathematical Analysis, Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, 119991 Moscow, Russia.
- Big Data and Information Retrieval School, Faculty of Computer Science, National Research University Higher School of Economics, 125319 Moscow, Russia.
- SRC Bioclinicum, 115088 Moscow, Russia.
| | | | | | - Ekaterina Kuzina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia.
| | | | - Alexander Gabibov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia.
- Big Data and Information Retrieval School, Faculty of Computer Science, National Research University Higher School of Economics, 125319 Moscow, Russia.
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia.
| | - Alexey Belogurov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia.
- Big Data and Information Retrieval School, Faculty of Computer Science, National Research University Higher School of Economics, 125319 Moscow, Russia.
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia.
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29
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Glycogen Shunt Activity and Glycolytic Supercompensation in Astrocytes May Be Distinctly Mediated via the Muscle Form of Glycogen Phosphorylase. Neurochem Res 2017; 42:2490-2494. [DOI: 10.1007/s11064-017-2267-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 03/31/2017] [Accepted: 04/10/2017] [Indexed: 02/08/2023]
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30
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Masgrau R, Guaza C, Ransohoff RM, Galea E. Should We Stop Saying 'Glia' and 'Neuroinflammation'? Trends Mol Med 2017; 23:486-500. [PMID: 28499701 DOI: 10.1016/j.molmed.2017.04.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/10/2017] [Accepted: 04/11/2017] [Indexed: 12/15/2022]
Abstract
Central nervous system (CNS) therapeutics based on the theoretical framework of neuroinflammation have only barely succeeded. We argue that a problem may be the wrong use of the term 'neuroinflammation' as a distinct nosological entity when, based on recent evidence, it may not explain CNS disease pathology. Indeed, the terms 'neuroinflammation' and 'glia' could be obsolete. First, unbiased molecular profiling of CNS cell populations and individual cells reveals striking phenotypic heterogeneity in health and disease. Second, astrocytes, microglia, oligodendrocytes, and NG2 cells may contribute to higher-brain functions by performing actions beyond housekeeping. We propose that CNS diseases be viewed as failed circuits caused in part by disease-specific dysfunction of cells traditionally called 'glia', and hence, favor therapies promoting their functional recovery.
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Affiliation(s)
- Roser Masgrau
- Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Medicina, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Carmen Guaza
- Neuroimmunology Group, Functional and Systems Neurobiology Department, Instituto Cajal, Agencia Estatal del Consejo Superior de Investigaciones Científicas, Madrid, España; Spanish Network of Multiple Sclerosis, RETICS, Instituto de Salud Carlos III, Madrid, España
| | | | - Elena Galea
- Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Medicina, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain; ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain.
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31
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Sousa C, Biber K, Michelucci A. Cellular and Molecular Characterization of Microglia: A Unique Immune Cell Population. Front Immunol 2017; 8:198. [PMID: 28303137 PMCID: PMC5332364 DOI: 10.3389/fimmu.2017.00198] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 02/09/2017] [Indexed: 12/26/2022] Open
Abstract
Microglia are essential for the development and function of the adult brain. Microglia arise from erythro-myeloid precursors in the yolk sac and populate the brain rudiment early during development. Unlike monocytes that are constantly renewed from bone marrow hematopoietic stem cells throughout life, resident microglia in the healthy brain persist during adulthood via constant self-renewal. Their ontogeny, together with the absence of turnover from the periphery and the singular environment of the central nervous system, make microglia a unique cell population. Supporting this notion, recent genome-wide transcriptional studies revealed specific gene expression profiles clearly distinct from other brain and peripheral immune cells. Here, we highlight the breakthrough studies that, over the last decades, helped elucidate microglial cell identity, ontogeny, and function. We describe the main techniques that have been used for this task and outline the crucial milestones that have been achieved to reach our actual knowledge of microglia. Furthermore, we give an overview of the “microgliome” that is currently emerging thanks to the constant progress in the modern profiling techniques.
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Affiliation(s)
- Carole Sousa
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg; Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg
| | - Knut Biber
- Department of Psychiatry and Psychotherapy, Section Molecular Psychiatry, University of Freiburg, Freiburg, Germany; Department of Neuroscience, Section Medical Physiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Alessandro Michelucci
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg; Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-Belval, Luxembourg
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32
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Rice RA, Pham J, Lee RJ, Najafi AR, West BL, Green KN. Microglial repopulation resolves inflammation and promotes brain recovery after injury. Glia 2017; 65:931-944. [PMID: 28251674 DOI: 10.1002/glia.23135] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/15/2017] [Accepted: 02/15/2017] [Indexed: 01/01/2023]
Abstract
Microglia mediate chronic neuroinflammation following central nervous system (CNS) disease or injury, and in doing so, damage the local brain environment by impairing recovery and contributing to disease processes. Microglia are critically dependent on signaling through the colony-stimulating factor 1 receptor (CSF1R) and can be eliminated via administration of CSF1R inhibitors. Resolving chronic neuroinflammation represents a universal goal for CNS disorders, but long-term microglial elimination may not be amenable to clinical use. Notably, withdrawal of CSF1R inhibitors stimulates new microglia to fully repopulate the CNS, affording an opportunity to renew this cellular compartment. To that end, we have explored the effects of acute microglial elimination, followed by microglial repopulation, in a mouse model of extensive neuronal loss. Neuronal loss leads to a prolonged neuroinflammatory response, characterized by the presence of swollen microglia expressing CD68 and CD45, as well as elevated levels of cytokines, chemokines, complement, and other inflammatory signals. These collective responses are largely resolved by microglial repopulation. Furthermore, microglial repopulation promotes functional recovery in mice, with elevated plus maze performance matching that of uninjured mice, despite the loss of 80% of hippocampal neurons. Analyses of synaptic surrogates revealed increases in PSD95 and synaptophysin puncta with microglial repopulation, suggesting that these cells sculpt and regulate the synaptic landscape. Thus, our results show that short-term microglial elimination followed by repopulation may represent a clinically feasible and novel approach to resolve neuroinflammatory events and promote brain recovery.
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Affiliation(s)
- Rachel A Rice
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California, 92697
| | - Jason Pham
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California, 92697
| | - Rafael J Lee
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California, 92697
| | - Allison R Najafi
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California, 92697
| | | | - Kim N Green
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California, 92697
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33
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Miller SJ, Zhang PW, Glatzer J, Rothstein JD. Astroglial transcriptome dysregulation in early disease of an ALS mutant SOD1 mouse model. J Neurogenet 2016; 31:37-48. [DOI: 10.1080/01677063.2016.1260128] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Sean J. Miller
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- The Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
- Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ping-wu Zhang
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- The Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Jenna Glatzer
- The Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Jeffrey D. Rothstein
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- The Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
- Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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34
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Abstract
As the immune-competent cells of the brain, microglia play an increasingly important role in maintaining normal brain function. They invade the brain early in development, transform into a highly ramified phenotype, and constantly screen their environment. Microglia are activated by any type of pathologic event or change in brain homeostasis. This activation process is highly diverse and depends on the context and type of the stressor or pathology. Microglia can strongly influence the pathologic outcome or response to a stressor due to the release of a plethora of substances, including cytokines, chemokines, and growth factors. They are the professional phagocytes of the brain and help orchestrate the immunological response by interacting with infiltrating immune cells. We describe here the diversity of microglia phenotypes and their responses in health, aging, and disease. We also review the current literature about the impact of lifestyle on microglia responses and discuss treatment options that modulate microglial phenotypes.
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Affiliation(s)
- Susanne A Wolf
- Cellular Neurosciences, Max Delbrück Centre for Molecular Medicine in the Helmholtz Association, Berlin 13092, Germany;
| | - H W G M Boddeke
- Department of Neuroscience, University of Groningen, University Medical Center Groningen, Groningen 9713, The Netherlands
| | - Helmut Kettenmann
- Cellular Neurosciences, Max Delbrück Centre for Molecular Medicine in the Helmholtz Association, Berlin 13092, Germany;
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35
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Oosterhof N, Holtman IR, Kuil LE, van der Linde HC, Boddeke EWGM, Eggen BJL, van Ham TJ. Identification of a conserved and acute neurodegeneration-specific microglial transcriptome in the zebrafish. Glia 2016; 65:138-149. [PMID: 27757989 PMCID: PMC5215681 DOI: 10.1002/glia.23083] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/21/2016] [Accepted: 09/28/2016] [Indexed: 12/29/2022]
Abstract
Microglia are brain resident macrophages important for brain development, connectivity, homeostasis and disease. However, it is still largely unclear how microglia functions and their identity are regulated at the molecular level. Although recent transcriptomic studies have identified genes specifically expressed in microglia, the function of most of these genes in microglia is still unknown. Here, we performed RNA sequencing on microglia acutely isolated from healthy and neurodegenerative zebrafish brains. We found that a large fraction of the mouse microglial signature is conserved in the zebrafish, corroborating the use of zebrafish to help understand microglial genetics in mammals in addition to studying basic microglia biology. Second, our transcriptome analysis of microglia following neuronal ablation suggested primarily a proliferative response of microglia, which we confirmed by immunohistochemistry and in vivo imaging. Together with the recent improvements in genome editing technology in zebrafish, these data offer opportunities to facilitate functional genetic research on microglia in vivo in the healthy as well as in the diseased brain. GLIA 2016;65:138–149
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Affiliation(s)
- Nynke Oosterhof
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, Wytemaweg 80, CN, 3015, The Netherlands
| | - Inge R Holtman
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 971 3, AV, Groningen, The Netherlands
| | - Laura E Kuil
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, Wytemaweg 80, CN, 3015, The Netherlands
| | - Herma C van der Linde
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, Wytemaweg 80, CN, 3015, The Netherlands
| | - Erik W G M Boddeke
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 971 3, AV, Groningen, The Netherlands
| | - Bart J L Eggen
- Department of Neuroscience, Section Medical Physiology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 971 3, AV, Groningen, The Netherlands
| | - Tjakko J van Ham
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, Wytemaweg 80, CN, 3015, The Netherlands
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36
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Abstract
Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and frontotemporal lobar dementia are among the most pressing problems of developed societies with aging populations. Neurons carry out essential functions such as signal transmission and network integration in the central nervous system and are the main targets of neurodegenerative disease. In this Review, I address how the neuron's environment also contributes to neurodegeneration. Maintaining an optimal milieu for neuronal function rests with supportive cells termed glia and the blood-brain barrier. Accumulating evidence suggests that neurodegeneration occurs in part because the environment is affected during disease in a cascade of processes collectively termed neuroinflammation. These observations indicate that therapies targeting glial cells might provide benefit for those afflicted by neurodegenerative disorders.
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37
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Rungta RL, Bernier LP, Dissing-Olesen L, Groten CJ, LeDue JM, Ko R, Drissler S, MacVicar BA. Ca 2+ transients in astrocyte fine processes occur via Ca 2+ influx in the adult mouse hippocampus. Glia 2016; 64:2093-2103. [PMID: 27479868 DOI: 10.1002/glia.23042] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 07/13/2016] [Indexed: 12/20/2022]
Abstract
Astrocytes display complex morphologies with an array of fine extensions extending from the soma and the primary thick processes. Until the use of genetically encoded calcium indicators (GECIs) selectively expressed in astrocytes, Ca2+ signaling was only examined in soma and thick primary processes of astrocytes where Ca2+ -sensitive fluorescent dyes could be imaged. GECI imaging in astrocytes revealed a previously unsuspected pattern of spontaneous Ca2+ transients in fine processes that has not been observed without chronic expression of GECIs, raising potential concerns about the effects of GECI expression. Here, we perform two-photon imaging of Ca2+ transients in adult CA1 hippocampal astrocytes using a new single-cell patch-loading strategy to image Ca2+ -sensitive fluorescent dyes in the cytoplasm of fine processes. We observed that astrocyte fine processes exhibited a high frequency of spontaneous Ca2+ transients whereas astrocyte soma rarely showed spontaneous Ca2+ oscillations similar to previous reports using GECIs. We exploited this new approach to show these signals were independent of neuronal spiking, metabotropic glutamate receptor (mGluR) activity, TRPA1 channels, and L- or T-type voltage-gated calcium channels. Removal of extracellular Ca2+ almost completely and reversibly abolished the spontaneous signals while IP3 R2 KO mice also exhibited spontaneous and compartmentalized signals, suggesting they rely on influx of extracellular Ca2+ . The Ca2+ influx dependency of the spontaneous signals in patch-loaded astrocytes was also observed in astrocytes expressing GCaMP3, further highlighting the presence of Ca2+ influx pathways in astrocytes. The mechanisms underlying these localized Ca2+ signals are critical for understanding how astrocytes regulate important functions in the adult brain. GLIA 2016;64:2093-2103.
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Affiliation(s)
- Ravi L Rungta
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Louis-Philippe Bernier
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Lasse Dissing-Olesen
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Christopher J Groten
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Jeffrey M LeDue
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Rebecca Ko
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Sibyl Drissler
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Brian A MacVicar
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, V6T 2B5, Canada.
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38
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Danbolt NC, Zhou Y, Furness DN, Holmseth S. Strategies for immunohistochemical protein localization using antibodies: What did we learn from neurotransmitter transporters in glial cells and neurons. Glia 2016; 64:2045-2064. [PMID: 27458697 DOI: 10.1002/glia.23027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/19/2016] [Accepted: 06/21/2016] [Indexed: 12/11/2022]
Abstract
Immunocytochemistry and Western blotting are still major methods for protein localization, but they rely on the specificity of the antibodies. Validation of antibody specificity remains challenging mostly because ideal negative controls are often unavailable. Further, immunochemical labeling patterns are also influenced by a number of other factors such as postmortem changes, fixation procedures and blocking agents as well as the general assay conditions (e.g., buffers, temperature, etc.). Western blotting similarly depends on tissue collection and sample preparation as well as the electrophoretic separation, transfer to blotting membranes and the immunochemical probing of immobilized molecules. Publication of inaccurate information on protein distribution has downstream consequences for other researchers because the interpretation of physiological and pharmacological observations depends on information on where ion channels, receptors, enzymes or transporters are located. Despite numerous reports, some of which are strongly worded, erroneous localization data are being published. Here we describe the extent of the problem and illustrate the nature of the pitfalls with examples from studies of neurotransmitter transporters. We explain the importance of supplementing immunochemical observations with other measurements (e.g., mRNA levels and distribution, protein activity, mass spectrometry, electrophysiological recordings, etc.) and why quantitative considerations are integral parts of the quality control. Further, we propose a practical strategy for researchers who plan to embark on a localization study. We also share our thoughts about guidelines for quality control. GLIA 2016;64:2045-2064.
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Affiliation(s)
- Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| | - Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - David N Furness
- School of Life Sciences, Keele University, Keele, Staffs, United Kingdom
| | - Silvia Holmseth
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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39
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Ishimura R, Nagy G, Dotu I, Chuang JH, Ackerman SL. Activation of GCN2 kinase by ribosome stalling links translation elongation with translation initiation. eLife 2016; 5. [PMID: 27085088 PMCID: PMC4917338 DOI: 10.7554/elife.14295] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/14/2016] [Indexed: 12/17/2022] Open
Abstract
Ribosome stalling during translation has recently been shown to cause neurodegeneration, yet the signaling pathways triggered by stalled elongation complexes are unknown. To investigate these pathways we analyzed the brain of C57BL/6J-Gtpbp2nmf205-/- mice in which neuronal elongation complexes are stalled at AGA codons due to deficiencies in a tRNAArgUCU tRNA and GTPBP2, a mammalian ribosome rescue factor. Increased levels of phosphorylation of eIF2α (Ser51) were detected prior to neurodegeneration in these mice and transcriptome analysis demonstrated activation of ATF4, a key transcription factor in the integrated stress response (ISR) pathway. Genetic experiments showed that this pathway was activated by the eIF2α kinase, GCN2, in an apparent deacylated tRNA-independent fashion. Further we found that the ISR attenuates neurodegeneration in C57BL/6J-Gtpbp2nmf205-/- mice, underscoring the importance of cellular and stress context on the outcome of activation of this pathway. These results demonstrate the critical interplay between translation elongation and initiation in regulating neuron survival during cellular stress. DOI:http://dx.doi.org/10.7554/eLife.14295.001 Information stored in DNA is used to make proteins in a two-step process. First, the DNA is copied to make molecules of messenger ribonucleic acid (or messenger RNA for short). Next, machines called ribosomes use the messenger RNAs as templates to assemble chains of amino acids – the building blocks of proteins – in a process called translation. Another type of RNA molecule called transfer RNA carries each amino acid to the ribosomes. If a specific transfer RNA is not available for translation at the right time, the ribosome might stall as it moves along the messenger RNA. At this point, the ribosome needs to be restarted or it will fall off the mRNA without finishing the protein. In 2014, a group of researchers reported that certain types of brain cells are very sensitive to ribosome stalling, and tend to die if translation does not continue. A protein called GTPBP2 was shown to play an important role in restarting stalled ribosomes in these cells. Here, Ishimura, Nagy et al. – including some of the researchers from the earlier work – investigated the molecular pathways that ribosome stalling triggers in brain cells using mutant mice that lacked the GTPBP2 protein. The experiments show that ribosome stalling activates an enzyme known as GCN2, which was already known to sense other types of malfunctions in cellular processes. Ishimura, Nagy et al. also show that GCN2 triggers stress responses in the cells by activating a communication system called the ATF4 pathway. This pathway protects the cells from damage, and its absence results in more rapid cell deterioration and death. The next challenges are to understand the exact mechanism by which GCN2 senses stalled ribosomes, and to find out how ribosome stalling causes the death of brain cells. DOI:http://dx.doi.org/10.7554/eLife.14295.002
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Affiliation(s)
- Ryuta Ishimura
- Howard Hughes Medical Institute, The Jackson Laboratory for Mammalian Genetics, Bar Harbor, United States
| | - Gabor Nagy
- Howard Hughes Medical Institute, The Jackson Laboratory for Mammalian Genetics, Bar Harbor, United States
| | - Ivan Dotu
- Research Programme on Biomedical Informatics, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Jeffrey H Chuang
- The Jackson Laboratory for Genomic Medicine, Farmington, United States.,Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, United States
| | - Susan L Ackerman
- Howard Hughes Medical Institute, The Jackson Laboratory for Mammalian Genetics, Bar Harbor, United States.,Department of Cell and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, United States.,Section of Neurobiology, University of California, La Jolla, United States
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Kaminska B, Mota M, Pizzi M. Signal transduction and epigenetic mechanisms in the control of microglia activation during neuroinflammation. Biochim Biophys Acta Mol Basis Dis 2016; 1862:339-51. [DOI: 10.1016/j.bbadis.2015.10.026] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/12/2015] [Accepted: 10/28/2015] [Indexed: 12/21/2022]
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Crotti A, Ransohoff RM. Microglial Physiology and Pathophysiology: Insights from Genome-wide Transcriptional Profiling. Immunity 2016; 44:505-515. [DOI: 10.1016/j.immuni.2016.02.013] [Citation(s) in RCA: 190] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 02/06/2016] [Accepted: 02/17/2016] [Indexed: 12/22/2022]
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Wes PD, Holtman IR, Boddeke EW, Möller T, Eggen BJ. Next generation transcriptomics and genomics elucidate biological complexity of microglia in health and disease. Glia 2015; 64:197-213. [DOI: 10.1002/glia.22866] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 05/11/2015] [Indexed: 12/11/2022]
Affiliation(s)
| | - Inge R. Holtman
- Department of NeuroscienceSection Medical Physiology, University of Groningen, University Medical Center GroningenGroningen The Netherlands
| | - Erik W.G.M. Boddeke
- Department of NeuroscienceSection Medical Physiology, University of Groningen, University Medical Center GroningenGroningen The Netherlands
| | | | - Bart J.L. Eggen
- Department of NeuroscienceSection Medical Physiology, University of Groningen, University Medical Center GroningenGroningen The Netherlands
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