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Field SE, Curle AJ, Barker RA. Inflammation and Huntington's disease - a neglected therapeutic target? Expert Opin Investig Drugs 2024; 33:451-467. [PMID: 38758356 DOI: 10.1080/13543784.2024.2348738] [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: 12/19/2023] [Accepted: 04/24/2024] [Indexed: 05/18/2024]
Abstract
INTRODUCTION Huntington's Disease (HD) is a genetic neurodegenerative disease for which there is currently no disease-modifying treatment. One of several underlying mechanisms proposed to be involved in HD pathogenesis is inflammation; there is now accumulating evidence that the immune system may play an integral role in disease pathology and progression. As such, modulation of the immune system could be a potential therapeutic target for HD. AREAS COVERED To date, the number of trials targeting immune aspects of HD has been limited. However, targeting it, may have great advantages over other therapeutic areas, given that many drugs already exist that have actions in this system coupled to the fact that inflammation can be measured both peripherally and, to some extent, centrally using CSF and PET imaging. In this review, we look at evidence that the immune system and the newly emerging area of the microbiome are altered in HD patients, and then present and discuss clinical trials that have targeted different parts of the immune system. EXPERT OPINION We then conclude by discussing how this field might develop going forward, focusing on the role of imaging and other biomarkers to monitor central immune activation and response to novel treatments in HD.
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Affiliation(s)
- Sophie E Field
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, and MRC-WT Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Annabel J Curle
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, and MRC-WT Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Roger A Barker
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, and MRC-WT Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
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Creus-Muncunill J, Haure-Mirande JV, Mattei D, Bons J, Ramirez AV, Hamilton BW, Corwin C, Chowdhury S, Schilling B, Ellerby LM, Ehrlich ME. TYROBP/DAP12 knockout in Huntington's disease Q175 mice cell-autonomously decreases microglial expression of disease-associated genes and non-cell-autonomously mitigates astrogliosis and motor deterioration. J Neuroinflammation 2024; 21:66. [PMID: 38459557 PMCID: PMC10924371 DOI: 10.1186/s12974-024-03052-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 02/19/2024] [Indexed: 03/10/2024] Open
Abstract
INTRODUCTION Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an expansion of the CAG trinucleotide repeat in the Huntingtin gene (HTT). Immune activation is abundant in the striatum of HD patients. Detection of active microglia at presymptomatic stages suggests that microgliosis is a key early driver of neuronal dysfunction and degeneration. Recent studies showed that deletion of Tyrobp, a microglial protein, ameliorates neuronal dysfunction in Alzheimer's disease amyloidopathy and tauopathy mouse models while decreasing components of the complement subnetwork. OBJECTIVE While TYROBP/DAP12-mediated microglial activation is detrimental for some diseases such as peripheral nerve injury, it is beneficial for other diseases. We sought to determine whether the TYROBP network is implicated in HD and whether Tyrobp deletion impacts HD striatal function and transcriptomics. METHODS To test the hypothesis that Tyrobp deficiency would be beneficial in an HD model, we placed the Q175 HD mouse model on a Tyrobp-null background. We characterized these mice with a combination of behavioral testing, immunohistochemistry, transcriptomic and proteomic profiling. Further, we evaluated the gene signature in isolated Q175 striatal microglia, with and without Tyrobp. RESULTS Comprehensive analysis of publicly available human HD transcriptomic data revealed that the TYROBP network is overactivated in the HD putamen. The Q175 mice showed morphologic microglial activation, reduced levels of post-synaptic density-95 protein and motor deficits at 6 and 9 months of age, all of which were ameliorated on the Tyrobp-null background. Gene expression analysis revealed that lack of Tyrobp in the Q175 model does not prevent the decrease in the expression of striatal neuronal genes but reduces pro-inflammatory pathways that are specifically active in HD human brain, including genes identified as detrimental in neurodegenerative diseases, e.g. C1q and members of the Ccr5 signaling pathway. Integration of transcriptomic and proteomic data revealed that astrogliosis and complement system pathway were reduced after Tyrobp deletion, which was further validated by immunofluorescence analysis. CONCLUSIONS Our data provide molecular and functional support demonstrating that Tyrobp deletion prevents many of the abnormalities in the HD Q175 mouse model, suggesting that the Tyrobp pathway is a potential therapeutic candidate for Huntington's disease.
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Affiliation(s)
| | | | - Daniele Mattei
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Joanna Bons
- Buck Institute for Research on Aging, Novato, CA, USA
| | - Angie V Ramirez
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - B Wade Hamilton
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Chuhyon Corwin
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Sarah Chowdhury
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, USA
| | | | | | - Michelle E Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, USA.
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Xu Y, Gao W, Sun Y, Wu M. New insight on microglia activation in neurodegenerative diseases and therapeutics. Front Neurosci 2023; 17:1308345. [PMID: 38188026 PMCID: PMC10770846 DOI: 10.3389/fnins.2023.1308345] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 12/06/2023] [Indexed: 01/09/2024] Open
Abstract
Microglia are immune cells within the central nervous system (CNS) closely linked to brain health and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. In response to changes in the surrounding environment, microglia activate and change their state and function. Several factors, example for circadian rhythm disruption and the development of neurodegenerative diseases, influence microglia activation. In this review, we explore microglia's function and the associated neural mechanisms. We elucidate that circadian rhythms are essential factors influencing microglia activation and function. Circadian rhythm disruption affects microglia activation and, consequently, neurodegenerative diseases. In addition, we found that abnormal microglia activation is a common feature of neurodegenerative diseases and an essential factor of disease development. Here we highlight the importance of microglia activation in neurodegenerative diseases. Targeting microglia for neurodegenerative disease treatment is a promising direction. We introduce the progress of methods targeting microglia for the treatment of neurodegenerative diseases and summarize the progress of drugs developed with microglia as targets, hoping to provide new ideas for treating neurodegenerative diseases.
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Affiliation(s)
- Yucong Xu
- Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Wei Gao
- Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yingnan Sun
- Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Minghua Wu
- Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
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Steinberg N, Galleguillos D, Zaidi A, Horkey M, Sipione S. Naïve Huntington's disease microglia mount a normal response to inflammatory stimuli but display a partially impaired development of innate immune tolerance that can be counteracted by ganglioside GM1. J Neuroinflammation 2023; 20:276. [PMID: 37996924 PMCID: PMC10668379 DOI: 10.1186/s12974-023-02963-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 11/18/2023] [Indexed: 11/25/2023] Open
Abstract
Chronic activation and dysfunction of microglia have been implicated in the pathogenesis and progression of many neurodegenerative disorders, including Huntington's disease (HD). HD is a genetic condition caused by a mutation that affects the folding and function of huntingtin (HTT). Signs of microglia activation have been observed in HD patients even before the onset of symptoms. It is unclear, however, whether pro-inflammatory microglia activation in HD results from cell-autonomous expression of mutant HTT, is the response of microglia to a diseased brain environment, or both. In this study, we used primary microglia isolated from HD knock-in (Q140) and wild-type (Q7) mice to investigate their response to inflammatory conditions in vitro in the absence of confounding effects arising from brain pathology. We show that naïve Q140 microglia do not undergo spontaneous pro-inflammatory activation and respond to inflammatory triggers, including stimulation of TLR4 and TLR2 and exposure to necrotic cells, with similar kinetics of pro-inflammatory gene expression as wild-type microglia. Upon termination of the inflammatory insult, the transcription of pro-inflammatory cytokines is tapered off in Q140 and wild-type microglia with similar kinetics. However, the ability of Q140 microglia to develop tolerance in response to repeated inflammatory stimulations is partially impaired in vitro and in vivo, potentially contributing to the establishment of chronic neuroinflammation in HD. We further show that ganglioside GM1, a glycosphingolipid with anti-inflammatory effects on wild-type microglia, not only decreases the production of pro-inflammatory cytokines and nitric oxide in activated Q140 microglia, but also dramatically dampen microglia response to re-stimulation with LPS in an experimental model of tolerance. These effects are independent from the expression of interleukin 1 receptor associated kinase 3 (Irak-3), a strong modulator of LPS signaling involved in the development of innate immune tolerance and previously shown to be upregulated by immune cell treatment with gangliosides. Altogether, our data suggest that external triggers are required for HD microglia activation, but a cell-autonomous dysfunction that affects the ability of HD microglia to acquire tolerance might contribute to the establishment of neuroinflammation in HD. Administration of GM1 might be beneficial to attenuate chronic microglia activation and neuroinflammation.
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Affiliation(s)
- Noam Steinberg
- Department of Pharmacology, Neuroscience and Mental Health Institute and Glycomics Institute of Alberta, University of Alberta, Edmonton, AB, Canada
| | - Danny Galleguillos
- Department of Pharmacology, Neuroscience and Mental Health Institute and Glycomics Institute of Alberta, University of Alberta, Edmonton, AB, Canada
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Asifa Zaidi
- Department of Pharmacology, Neuroscience and Mental Health Institute and Glycomics Institute of Alberta, University of Alberta, Edmonton, AB, Canada
| | | | - Simonetta Sipione
- Department of Pharmacology, Neuroscience and Mental Health Institute and Glycomics Institute of Alberta, University of Alberta, Edmonton, AB, Canada.
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Wilton DK, Mastro K, Heller MD, Gergits FW, Willing CR, Fahey JB, Frouin A, Daggett A, Gu X, Kim YA, Faull RLM, Jayadev S, Yednock T, Yang XW, Stevens B. Microglia and complement mediate early corticostriatal synapse loss and cognitive dysfunction in Huntington's disease. Nat Med 2023; 29:2866-2884. [PMID: 37814059 PMCID: PMC10667107 DOI: 10.1038/s41591-023-02566-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 08/24/2023] [Indexed: 10/11/2023]
Abstract
Huntington's disease (HD) is a devastating monogenic neurodegenerative disease characterized by early, selective pathology in the basal ganglia despite the ubiquitous expression of mutant huntingtin. The molecular mechanisms underlying this region-specific neuronal degeneration and how these relate to the development of early cognitive phenotypes are poorly understood. Here we show that there is selective loss of synaptic connections between the cortex and striatum in postmortem tissue from patients with HD that is associated with the increased activation and localization of complement proteins, innate immune molecules, to these synaptic elements. We also found that levels of these secreted innate immune molecules are elevated in the cerebrospinal fluid of premanifest HD patients and correlate with established measures of disease burden.In preclinical genetic models of HD, we show that complement proteins mediate the selective elimination of corticostriatal synapses at an early stage in disease pathogenesis, marking them for removal by microglia, the brain's resident macrophage population. This process requires mutant huntingtin to be expressed in both cortical and striatal neurons. Inhibition of this complement-dependent elimination mechanism through administration of a therapeutically relevant C1q function-blocking antibody or genetic ablation of a complement receptor on microglia prevented synapse loss, increased excitatory input to the striatum and rescued the early development of visual discrimination learning and cognitive flexibility deficits in these models. Together, our findings implicate microglia and the complement cascade in the selective, early degeneration of corticostriatal synapses and the development of cognitive deficits in presymptomatic HD; they also provide new preclinical data to support complement as a therapeutic target for early intervention.
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Affiliation(s)
- Daniel K Wilton
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US.
| | - Kevin Mastro
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Molly D Heller
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Frederick W Gergits
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Carly Rose Willing
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Jaclyn B Fahey
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Arnaud Frouin
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Anthony Daggett
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Xiaofeng Gu
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Yejin A Kim
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Richard L M Faull
- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Suman Jayadev
- Department of Neurology, University of Washington, Seattle, WA, USA
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Ted Yednock
- Annexon Biosciences, South San Francisco, CA, USA
| | - X William Yang
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Beth Stevens
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US.
- Stanley Center, Broad Institute, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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6
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Cvetanovic M, Gray M. Contribution of Glial Cells to Polyglutamine Diseases: Observations from Patients and Mouse Models. Neurotherapeutics 2023; 20:48-66. [PMID: 37020152 PMCID: PMC10119372 DOI: 10.1007/s13311-023-01357-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2023] [Indexed: 04/07/2023] Open
Abstract
Neurodegenerative diseases are broadly characterized neuropathologically by the degeneration of vulnerable neuronal cell types in a specific brain region. The degeneration of specific cell types has informed on the various phenotypes/clinical presentations in someone suffering from these diseases. Prominent neurodegeneration of specific neurons is seen in polyglutamine expansion diseases including Huntington's disease (HD) and spinocerebellar ataxias (SCA). The clinical manifestations observed in these diseases could be as varied as the abnormalities in motor function observed in those who have Huntington's disease (HD) as demonstrated by a chorea with substantial degeneration of striatal medium spiny neurons (MSNs) or those with various forms of spinocerebellar ataxia (SCA) with an ataxic motor presentation primarily due to degeneration of cerebellar Purkinje cells. Due to the very significant nature of the degeneration of MSNs in HD and Purkinje cells in SCAs, much of the research has centered around understanding the cell autonomous mechanisms dysregulated in these neuronal cell types. However, an increasing number of studies have revealed that dysfunction in non-neuronal glial cell types contributes to the pathogenesis of these diseases. Here we explore these non-neuronal glial cell types with a focus on how each may contribute to the pathogenesis of HD and SCA and the tools used to evaluate glial cells in the context of these diseases. Understanding the regulation of supportive and harmful phenotypes of glia in disease could lead to development of novel glia-focused neurotherapeutics.
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Affiliation(s)
- Marija Cvetanovic
- Department of Neuroscience, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, USA
| | - Michelle Gray
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL, USA.
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Saba J, Couselo FL, Bruno J, Carniglia L, Durand D, Lasaga M, Caruso C. Neuroinflammation in Huntington's Disease: A Starring Role for Astrocyte and Microglia. Curr Neuropharmacol 2022; 20:1116-1143. [PMID: 34852742 PMCID: PMC9886821 DOI: 10.2174/1570159x19666211201094608] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/06/2021] [Accepted: 11/26/2021] [Indexed: 11/22/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative genetic disorder caused by a CAG repeat expansion in the huntingtin gene. HD causes motor, cognitive, and behavioral dysfunction. Since no existing treatment affects the course of this disease, new treatments are needed. Inflammation is frequently observed in HD patients before symptom onset. Neuroinflammation, characterized by the presence of reactive microglia, astrocytes and inflammatory factors within the brain, is also detected early. However, in comparison to other neurodegenerative diseases, the role of neuroinflammation in HD is much less known. Work has been dedicated to altered microglial and astrocytic functions in the context of HD, but less attention has been given to glial participation in neuroinflammation. This review describes evidence of inflammation in HD patients and animal models. It also discusses recent knowledge on neuroinflammation in HD, highlighting astrocyte and microglia involvement in the disease and considering anti-inflammatory therapeutic approaches.
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Affiliation(s)
- Julieta Saba
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Federico López Couselo
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Julieta Bruno
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Lila Carniglia
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Daniela Durand
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mercedes Lasaga
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carla Caruso
- Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina,Address correspondence to this author at the Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Paraguay 2155 Piso 10, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina, Tel: +54 11 5285 3380; E-mail:
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Kacher R, Mounier C, Caboche J, Betuing S. Altered Cholesterol Homeostasis in Huntington’s Disease. Front Aging Neurosci 2022; 14:797220. [PMID: 35517051 PMCID: PMC9063567 DOI: 10.3389/fnagi.2022.797220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 03/18/2022] [Indexed: 12/25/2022] Open
Abstract
Huntington’s disease (HD) is an autosomal dominant genetic disorder caused by an expansion of the CAG repeat in the first exon of Huntingtin’s gene. The associated neurodegeneration mainly affects the striatum and the cortex at early stages and progressively spreads to other brain structures. Targeting HD at its earlier stages is under intense investigation. Numerous drugs were tested, with a rate of success of only 3.5% approved molecules used as symptomatic treatment. The restoration of cholesterol metabolism, which is central to the brain homeostasis and strongly altered in HD, could be an interesting disease-modifying strategy. Cholesterol is an essential membrane component in the central nervous system (CNS); alterations of its homeostasis have deleterious consequences on neuronal functions. The levels of several sterols, upstream of cholesterol, are markedly decreased within the striatum of HD mouse model. Transcription of cholesterol biosynthetic genes is reduced in HD cell and mouse models as well as post-mortem striatal and cortical tissues from HD patients. Since the dynamic of brain cholesterol metabolism is complex, it is essential to establish the best method to target it in HD. Cholesterol, which does not cross the blood-brain-barrier, is locally synthesized and renewed within the brain. All cell types in the CNS synthesize cholesterol during development but as they progress through adulthood, neurons down-regulate their cholesterol synthesis and turn to astrocytes for their full supply. Cellular levels of cholesterol reflect the dynamic balance between synthesis, uptake and export, all integrated into the context of the cross talk between neurons and glial cells. In this review, we describe the latest advances regarding the role of cholesterol deregulation in neuronal functions and how this could be a determinant factor in neuronal degeneration and HD progression. The pathways and major mechanisms by which cholesterol and sterols are regulated in the CNS will be described. From this overview, we discuss the main clinical strategies for manipulating cholesterol metabolism in the CNS, and how to reinstate a proper balance in HD.
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Affiliation(s)
- Radhia Kacher
- Institut du Cerveau - Paris Brain Institute (ICM), AP-HP, INSERM, CNRS, University Hospital Pitié-Salpêtrière, Sorbonne Université, Paris, France
- INSERM, U1216, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France
| | - Coline Mounier
- Neuroscience Paris Seine, Institut de Biologie Paris-Seine, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Paris, France
- U1130, Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Jocelyne Caboche
- Neuroscience Paris Seine, Institut de Biologie Paris-Seine, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Paris, France
- U1130, Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Sandrine Betuing
- Neuroscience Paris Seine, Institut de Biologie Paris-Seine, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
- Centre National de la Recherche Scientifique, UMR 8246, Paris, France
- U1130, Institut National de la Santé et de la Recherche Médicale, Paris, France
- *Correspondence: Sandrine Betuing,
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Redefining microglia states: Lessons and limits of human and mouse models to study microglia states in neurodegenerative diseases. Semin Immunol 2022; 60:101651. [PMID: 36155944 DOI: 10.1016/j.smim.2022.101651] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 09/03/2022] [Indexed: 01/15/2023]
Abstract
Microglia are resident macrophages of the brain parenchyma and play an essential role in various aspects of brain development, plasticity, and homeostasis. With recent advances in single-cell RNA-sequencing, heterogeneous microglia transcriptional states have been identified in both animal models of neurodegenerative disorders and patients. However, the functional roles of these microglia states remain unclear; specifically, the question of whether individual states or combinations of states are protective or detrimental (or both) in the context of disease progression. To attempt to answer this, the field has largely relied on studies employing mouse models, human in vitro and chimeric models, and human post-mortem tissue, all of which have their caveats, but used in combination can enable new biological insight and validation of candidate disease pathways and mechanisms. In this review, we summarize our current understanding of disease-associated microglia states and phenotypes in neurodegenerative disorders, discuss important considerations when comparing mouse and human microglia states and functions, and identify areas of microglia biology where species differences might limit our understanding of microglia state.
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Villegas L, Nørremølle A, Freude K, Vilhardt F. Nicotinamide Adenine Dinucleotide Phosphate Oxidases Are Everywhere in Brain Disease, but Not in Huntington's Disease? Front Aging Neurosci 2021; 13:736734. [PMID: 34803655 PMCID: PMC8602359 DOI: 10.3389/fnagi.2021.736734] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
Huntington’s disease (HD) is an inherited neurodegenerative disorder characterized by neuronal loss and tissue atrophy mainly in the striatum and cortex. In the early stages of the disease, impairment of neuronal function, synaptic dysfunction and white matter loss precedes neuronal death itself. Relative to other neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease and Amyotrophic Lateral Sclerosis, where the effects of either microglia or NADPH oxidases (NOXs) are recognized as important contributors to disease pathogenesis and progression, there is a pronounced lack of information in HD. This information void contrasts with evidence from human HD patients where blood monocytes and microglia are activated well before HD clinical symptoms (PET scans), and the clear signs of oxidative stress and inflammation in post mortem HD brain. Habitually, NOX activity and oxidative stress in the central nervous system (CNS) are equated with microglia, but research of the last two decades has carved out important roles for NOX enzyme function in neurons. Here, we will convey recent information about the function of NOX enzymes in neurons, and contemplate on putative roles of neuronal NOX in HD. We will focus on NOX-produced reactive oxygen species (ROS) as redox signaling molecules in/among neurons, and the specific roles of NOXs in important processes such as neurogenesis and lineage specification, neurite outgrowth and growth cone dynamics, and synaptic plasticity where NMDAR-dependent signaling, and long-term depression/potentiation are redox-regulated phenomena. HD animal models and induced pluripotent stem cell (iPSC) studies have made it clear that the very same physiological processes are also affected in HD, and we will speculate on possible roles for NOX in the pathogenesis and development of disease. Finally, we also take into account the limited information on microglia in HD and relate this to any contribution of NOX enzymes.
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Affiliation(s)
- Luisana Villegas
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Anne Nørremølle
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Kristine Freude
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Frederik Vilhardt
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
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Al-Shekaili HH, Petkau TL, Pena I, Lengyell TC, Verhoeven-Duif NM, Ciapaite J, Bosma M, van Faassen M, Kema IP, Horvath G, Ross C, Simpson EM, Friedman JM, van Karnebeek C, Leavitt BR. A novel mouse model for pyridoxine-dependent epilepsy due to antiquitin deficiency. Hum Mol Genet 2021; 29:3266-3284. [PMID: 32969477 DOI: 10.1093/hmg/ddaa202] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/18/2020] [Accepted: 08/27/2020] [Indexed: 01/09/2023] Open
Abstract
Pyridoxine-dependent epilepsy (PDE) is a rare autosomal recessive disease caused by mutations in the ALDH7A1 gene leading to blockade of the lysine catabolism pathway. PDE is characterized by recurrent seizures that are resistant to conventional anticonvulsant treatment but are well-controlled by pyridoxine (PN). Most PDE patients also suffer from neurodevelopmental deficits despite adequate seizure control with PN. To investigate potential pathophysiological mechanisms associated with ALDH7A1 deficiency, we generated a transgenic mouse strain with constitutive genetic ablation of Aldh7a1. We undertook extensive biochemical characterization of Aldh7a1-KO mice consuming a low lysine/high PN diet. Results showed that KO mice accumulated high concentrations of upstream lysine metabolites including ∆1-piperideine-6-carboxylic acid (P6C), α-aminoadipic semialdehyde (α-AASA) and pipecolic acid both in brain and liver tissues, similar to the biochemical picture in ALDH7A1-deficient patients. We also observed preliminary evidence of a widely deranged amino acid profile and increased levels of methionine sulfoxide, an oxidative stress biomarker, in the brains of KO mice, suggesting that increased oxidative stress may be a novel pathobiochemical mechanism in ALDH7A1 deficiency. KO mice lacked epileptic seizures when fed a low lysine/high PN diet. Switching mice to a high lysine/low PN diet led to vigorous seizures and a quick death in KO mice. Treatment with PN controlled seizures and improved survival of high-lysine/low PN fed KO mice. This study expands the spectrum of biochemical abnormalities that may be associated with ALDH7A1 deficiency and provides a proof-of-concept for the utility of the model to study PDE pathophysiology and to test new therapeutics.
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Affiliation(s)
- Hilal H Al-Shekaili
- British Columbia Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Terri L Petkau
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Izabella Pena
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Tess C Lengyell
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | | | - Jolita Ciapaite
- Department of Genetics, University Medical Center, Utrecht, The Netherlands
| | - Marjolein Bosma
- Department of Genetics, University Medical Center, Utrecht, The Netherlands
| | - Martijn van Faassen
- Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ido P Kema
- Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gabriella Horvath
- Division of Biochemical Diseases, Department of Pediatrics, University of British Columbia and BC Children's Hospital, Vancouver, BC, Canada
| | - Colin Ross
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Elizabeth M Simpson
- British Columbia Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Jan M Friedman
- British Columbia Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Clara van Karnebeek
- Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, BC Children's Research Institute, University of British Columbia, Vancouver, BC, Canada.,Department of Pediatrics, Emma Children's Hospital, Amsterdam University Medical Centres, Amsterdam, The Netherlands.,Department of Pediatrics, Amalia Children's Hospital, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Blair R Leavitt
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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12
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Cheong RY, Baldo B, Sajjad MU, Kirik D, Petersén Å. Effects of mutant huntingtin inactivation on Huntington disease-related behaviours in the BACHD mouse model. Neuropathol Appl Neurobiol 2021; 47:564-578. [PMID: 33330988 PMCID: PMC8247873 DOI: 10.1111/nan.12682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/27/2020] [Accepted: 12/14/2020] [Indexed: 01/02/2023]
Abstract
AIMS Huntington disease (HD) is a fatal neurodegenerative disorder with no disease-modifying treatments approved so far. Ongoing clinical trials are attempting to reduce huntingtin (HTT) expression in the central nervous system (CNS) using different strategies. Yet, the distribution and timing of HTT-lowering therapies required for a beneficial clinical effect is less clear. Here, we investigated whether HD-related behaviours could be prevented by inactivating mutant HTT at different disease stages and to varying degrees in an experimental model. METHODS We generated mutant BACHD mice with either a widespread or circuit-specific inactivation of mutant HTT by using Cre recombinase (Cre) under the nestin promoter or the adenosine A2A receptor promoter respectively. We also simulated a clinical gene therapy scenario with allele-specific HTT targeting by injections of recombinant adeno-associated viral (rAAV) vectors expressing Cre into the striatum of adult BACHD mice. All mice were assessed using behavioural tests to investigate motor, metabolic and psychiatric outcome measures at 4-6 months of age. RESULTS While motor deficits, body weight changes, anxiety and depressive-like behaviours are present in BACHD mice, early widespread CNS inactivation during development significantly improves rotarod performance, body weight changes and depressive-like behaviour. However, conditional circuit-wide mutant HTT deletion from the indirect striatal pathway during development and focal striatal-specific deletion in adulthood failed to rescue any of the HD-related behaviours. CONCLUSIONS Our results indicate that widespread targeting and the timing of interventions aimed at reducing mutant HTT are important factors to consider when developing disease-modifying therapies for HD.
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Affiliation(s)
- Rachel Y. Cheong
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Barbara Baldo
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
- Present address:
Evotec SEHD Research and Translational SciencesHamburgGermany
| | - Muhammad U. Sajjad
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Deniz Kirik
- Brain Repair and Imaging in Neural Systems UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Åsa Petersén
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
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13
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Manickam N, Radhakrishnan RK, Vergil Andrews JF, Selvaraj DB, Kandasamy M. Cell cycle re-entry of neurons and reactive neuroblastosis in Huntington's disease: Possibilities for neural-glial transition in the brain. Life Sci 2020; 263:118569. [PMID: 33049278 DOI: 10.1016/j.lfs.2020.118569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 02/07/2023]
Abstract
Huntington's disease (HD) is an autosomal dominant pathogenic condition that causes progressive degeneration of GABAergic neurons in the brain. The abnormal expansion of the CAG repeats in the exon 1 of the Huntingtin gene (HTT gene) has been associated with the onset and progression of movement disorders, psychiatric disturbance and cognitive decline in HD. Microglial activation and reactive astrogliosis have been recognized as the key pathogenic cellular events in the brains of HD subjects. Besides, HD has been characterized by induced quiescence of neural stem cells (NSCs), reactive neuroblastosis and reduced survival of newborn neurons in the brain. Strikingly, the expression of the mutant HTT gene has been reported to induce the cell cycle re-entry of neurons in HD brains. However, the underlying basis for the induction of cell cycle in neurons and the fate of dedifferentiating neurons in the pathological brain remain largely unknown. Thus, this review article revisits the reports on the regulation of key signaling pathways responsible for altered cell cycle events in diseased brains, with special reference to HD and postulates the occurrence of reactive neuroblastosis as a consequential cellular event of dedifferentiation of neurons. Meanwhile, a substantial number of studies indicate that many neuropathogenic events are associated with the expression of potential glial cell markers by neuroblasts. Taken together, this article represents a hypothesis that transdifferentiation of neurons into glial cells might be highly possible through the transient generation of reactive neuroblasts in the brain upon certain pathological conditions.
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Affiliation(s)
- Nivethitha Manickam
- Laboratory of Stem Cells and Neuroregeneration, Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| | - Risna Kanjirassery Radhakrishnan
- Laboratory of Stem Cells and Neuroregeneration, Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| | - Jemi Feiona Vergil Andrews
- Laboratory of Stem Cells and Neuroregeneration, Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| | - Divya Bharathi Selvaraj
- Laboratory of Stem Cells and Neuroregeneration, Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| | - Mahesh Kandasamy
- Laboratory of Stem Cells and Neuroregeneration, Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India; Faculty Recharge Programme, University Grants Commission (UGC-FRP), New Delhi 110002, India.
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14
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Crapser JD, Ochaba J, Soni N, Reidling JC, Thompson LM, Green KN. Microglial depletion prevents extracellular matrix changes and striatal volume reduction in a model of Huntington's disease. Brain 2020; 143:266-288. [PMID: 31848580 DOI: 10.1093/brain/awz363] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 08/22/2019] [Accepted: 10/01/2019] [Indexed: 12/12/2022] Open
Abstract
Huntington's disease is associated with a reactive microglial response and consequent inflammation. To address the role of these cells in disease pathogenesis, we depleted microglia from R6/2 mice, a rapidly progressing model of Huntington's disease marked by behavioural impairment, mutant huntingtin (mHTT) accumulation, and early death, through colony-stimulating factor 1 receptor inhibition (CSF1Ri) with pexidartinib (PLX3397) for the duration of disease. Although we observed an interferon gene signature in addition to downregulated neuritogenic and synaptic gene pathways with disease, overt inflammation was not evident by microglial morphology or cytokine transcript levels in R6/2 mice. Nonetheless, CSF1Ri-induced microglial elimination reduced or prevented disease-related grip strength and object recognition deficits, mHTT accumulation, astrogliosis, and striatal volume loss, the latter of which was not associated with reductions in cell number but with the extracellular accumulation of chondroitin sulphate proteoglycans (CSPGs)-a primary component of glial scars. A concurrent loss of proteoglycan-containing perineuronal nets was also evident in R6/2 mice, and microglial elimination not only prevented this but also strikingly increased perineuronal nets in the brains of naïve littermates, suggesting a new role for microglia as homeostatic regulators of perineuronal net formation and integrity.
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Affiliation(s)
- Joshua D Crapser
- Department of Neurobiology and Behavior, University of California, Irvine (UCI), Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Joseph Ochaba
- Department of Neurobiology and Behavior, University of California, Irvine (UCI), Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Neelakshi Soni
- Department of Neurobiology and Behavior, University of California, Irvine (UCI), Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Jack C Reidling
- Department of Neurobiology and Behavior, University of California, Irvine (UCI), Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Leslie M Thompson
- Department of Neurobiology and Behavior, University of California, Irvine (UCI), Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA.,Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA
| | - Kim N Green
- Department of Neurobiology and Behavior, University of California, Irvine (UCI), Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
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15
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Fatoba O, Itokazu T, Yamashita T. Microglia as therapeutic target in central nervous system disorders. J Pharmacol Sci 2020; 144:102-118. [PMID: 32921391 DOI: 10.1016/j.jphs.2020.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/19/2020] [Accepted: 07/07/2020] [Indexed: 12/17/2022] Open
Abstract
Chronic microglial activation is associated with the pathogenesis of several CNS disorders. Microglia show phenotypic diversity and functional complexity in diseased CNS. Thus, understanding the pathology-specific heterogeneity of microglial behavior is crucial for the future development of microglia-modulating therapy for variety of CNS disorders. This review summarizes up-to-date knowledge on how microglia contribute to CNS homeostasis during development and throughout adulthood. We discuss the heterogeneity of microglial phenotypes in the context of CNS disorders with an emphasis on neurodegenerative diseases, demyelinating diseases, CNS trauma, and epilepsy. We conclude this review with a discussion about the disease-specific heterogeneity of microglial function and how it could be exploited for therapeutic intervention.
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Affiliation(s)
- Oluwaseun Fatoba
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI-Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Takahide Itokazu
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI-Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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16
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Wilton DK, Stevens B. The contribution of glial cells to Huntington's disease pathogenesis. Neurobiol Dis 2020; 143:104963. [PMID: 32593752 DOI: 10.1016/j.nbd.2020.104963] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 05/07/2020] [Accepted: 06/10/2020] [Indexed: 12/20/2022] Open
Abstract
Glial cells play critical roles in the normal development and function of neural circuits, but in many neurodegenerative diseases, they become dysregulated and may contribute to the development of brain pathology. In Huntington's disease (HD), glial cells both lose normal functions and gain neuropathic phenotypes. In addition, cell-autonomous dysfunction elicited by mutant huntingtin (mHTT) expression in specific glial cell types is sufficient to induce both pathology and Huntington's disease-related impairments in motor and cognitive performance, suggesting that these cells may drive the development of certain aspects of Huntington's disease pathogenesis. In support of this imaging studies in pre-symptomatic HD patients and work on mouse models have suggested that glial cell dysfunction occurs at a very early stage of the disease, prior to the onset of motor and cognitive deficits. Furthermore, selectively ablating mHTT from specific glial cells or correcting for HD-induced changes in their transcriptional profile rescues some HD-related phenotypes, demonstrating the potential of targeting these cells for therapeutic intervention. Here we review emerging research focused on understanding the involvement of different glial cell types in specific aspects of HD pathogenesis. This work is providing new insight into how HD impacts biological functions of glial cells in the healthy brain as well as how HD induced dysfunction in these cells might change the way they integrate into biological circuits.
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Affiliation(s)
- Daniel K Wilton
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Beth Stevens
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Stanley Center, Broad Institute, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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17
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Gleichman AJ, Carmichael ST. Glia in neurodegeneration: Drivers of disease or along for the ride? Neurobiol Dis 2020; 142:104957. [PMID: 32512150 DOI: 10.1016/j.nbd.2020.104957] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 05/13/2020] [Accepted: 06/03/2020] [Indexed: 02/08/2023] Open
Abstract
While much of the research on neurodegenerative diseases has focused on neurons, non-neuronal cells are also affected. The extent to which glia and other non-neuronal cells are causally involved in disease pathogenesis versus more passively responding to disease is an area of active research. This is complicated by the fact that there is rarely one known cause of neurodegenerative diseases; rather, these disorders likely involve feedback loops that perpetuate dysfunction. Here, we will review genetic as well as experimental evidence that suggest that non-neuronal cells are at least partially driving disease pathogenesis in numerous neurodegenerative disorders, including Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis, Huntington's disease, multiple sclerosis, and Parkinson's disease.
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Affiliation(s)
- Amy J Gleichman
- Department of Neurology, David Geffen School of Medicine, University of California - Los Angeles, Los Angeles, CA 90095, United States.
| | - S Thomas Carmichael
- Department of Neurology, David Geffen School of Medicine, University of California - Los Angeles, Los Angeles, CA 90095, United States
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18
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Savage JC, St-Pierre MK, Carrier M, El Hajj H, Novak SW, Sanchez MG, Cicchetti F, Tremblay MÈ. Microglial physiological properties and interactions with synapses are altered at presymptomatic stages in a mouse model of Huntington's disease pathology. J Neuroinflammation 2020; 17:98. [PMID: 32241286 PMCID: PMC7118932 DOI: 10.1186/s12974-020-01782-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder that affects cognitive and motor abilities by primarily targeting the striatum and cerebral cortex. HD is caused by a mutation elongating the CAG repeats within the Huntingtin gene, resulting in HTT protein misfolding. Although the genetic cause of HD has been established, the specific susceptibility of neurons within various brain structures has remained elusive. Microglia, which are the brain's resident macrophages, have emerged as important players in neurodegeneration. Nevertheless, few studies have examined their implication in HD. METHODS To provide novel insights, we investigated the maturation and dysfunction of striatal microglia using the R6/2 mouse model of HD. This transgenic model, which presents with 120+/-5 CAG repeats, displays progressive motor deficits beginning at 6 weeks of age, with full incapacitation by 13 weeks. We studied microglial morphology, phagocytic capacity, and synaptic contacts in the striatum of R6/2 versus wild-type (WT) littermates at 3, 10, and 13 weeks of age, using a combination of light and transmission electron microscopy. We also reconstructed dendrites and determined synaptic density within the striatum of R6/2 and WT littermates, at nanoscale resolution using focused ion beam scanning electron microscopy. RESULTS At 3 weeks of age, prior to any known motor deficits, microglia in R6/2 animals displayed a more mature morphological phenotype than WT animals. Microglia from R6/2 mice across all ages also demonstrated increased phagocytosis, as revealed by light microscopy and transmission electron microscopy. Furthermore, microglial processes from 10-week-old R6/2 mice made fewer contacts with synaptic structures than microglial processes in 3-week-old R6/2 mice and age-matched WT littermates. Synaptic density was not affected by genotype at 3 weeks of age but increased with maturation in WT mice. The location of synapses was lastly modified in R6/2 mice compared with WT controls, from targeting dendritic spines to dendritic trunks at both 3 and 10 weeks of age. CONCLUSIONS These findings suggest that microglia may play an intimate role in synaptic alteration and loss during HD pathogenesis.
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Affiliation(s)
- Julie C Savage
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada.
| | - Marie-Kim St-Pierre
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Micaël Carrier
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Hassan El Hajj
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Sammy Weiser Novak
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
- Waitt Advanced Biophotonics Core, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Maria Gabriela Sanchez
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Francesca Cicchetti
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
- Département de psychiatrie et neurosciences, Faculté de médecine, Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada.
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Québec, QC, Canada.
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.
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19
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Hopp SC. Targeting microglia L-type voltage-dependent calcium channels for the treatment of central nervous system disorders. J Neurosci Res 2020; 99:141-162. [PMID: 31997405 DOI: 10.1002/jnr.24585] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/03/2020] [Accepted: 01/08/2020] [Indexed: 12/14/2022]
Abstract
Calcium (Ca2+ ) is a ubiquitous mediator of a multitude of cellular functions in the central nervous system (CNS). Intracellular Ca2+ is tightly regulated by cells, including entry via plasma membrane Ca2+ permeable channels. Of specific interest for this review are L-type voltage-dependent Ca2+ channels (L-VDCCs), due to their pleiotropic role in several CNS disorders. Currently, there are numerous approved drugs that target L-VDCCs, including dihydropyridines. These drugs are safe and effective for the treatment of humans with cardiovascular disease and may also confer neuroprotection. Here, we review the potential of L-VDCCs as a target for the treatment of CNS disorders with a focus on microglia L-VDCCs. Microglia, the resident immune cells of the brain, have attracted recent attention for their emerging inflammatory role in several CNS diseases. Intracellular Ca2+ regulates microglia transition from a resting quiescent state to an "activated" immune-effector state and is thus a valuable target for manipulation of microglia phenotype. We will review the literature on L-VDCC expression and function in the CNS and on microglia in vitro and in vivo and explore the therapeutic landscape of L-VDCC-targeting agents at present and future challenges in the context of Alzheimer's disease, Parkinson's disease, Huntington's disease, neuropsychiatric diseases, and other CNS disorders.
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Affiliation(s)
- Sarah C Hopp
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.,Department of Pharmacology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
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20
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Palpagama TH, Waldvogel HJ, Faull RLM, Kwakowsky A. The Role of Microglia and Astrocytes in Huntington's Disease. Front Mol Neurosci 2019; 12:258. [PMID: 31708741 PMCID: PMC6824292 DOI: 10.3389/fnmol.2019.00258] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 10/10/2019] [Indexed: 12/21/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease. HD patients present with movement disorders, behavioral and psychiatric symptoms and cognitive decline. This review summarizes the contribution of microglia and astrocytes to HD pathophysiology. Neuroinflammation in the HD brain is characterized by a reactive morphology in these glial cells. Microglia and astrocytes are critical in regulating neuronal activity and maintaining an optimal milieu for neuronal function. Previous studies provide evidence that activated microglia and reactive astrocytes contribute to HD pathology through transcriptional activation of pro-inflammatory genes to perpetuate a chronic inflammatory state. Reactive astrocytes also display functional changes in glutamate and ion homeostasis and energy metabolism. Astrocytic and microglial changes may further contribute to the neuronal death observed with the progression of HD. Importantly, the degree to which these neuroinflammatory changes are detrimental to neurons and contribute to the progression of HD pathology is not well understood. Furthermore, recent observations provide compelling evidence that activated microglia and astrocytes exert a variety of beneficial functions that are essential for limiting tissue damage and preserving neuronal function in the HD brain. Therefore, a better understanding of the neuroinflammatory environment in the brain in HD may lead to the development of targeted and innovative therapeutic opportunities.
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Affiliation(s)
- Thulani H Palpagama
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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21
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Kosior N, Petkau TL, Connolly C, Lu G, Leavitt BR. Isolating cells from adult murine brain for validation of cell-type specific cre-mediated deletion. J Neurosci Methods 2019; 328:108422. [PMID: 31493416 DOI: 10.1016/j.jneumeth.2019.108422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 09/03/2019] [Accepted: 09/03/2019] [Indexed: 01/05/2023]
Abstract
BACKGROUND TheCre/loxP system allows for the temporal and spatial investigation of the expression of a single gene in the nervous system. Current methods of validating conditional knock-out mouse models rely on heterogeneous brain tissue or primary culture. These methods may assess the extent of genetic knockdown in the brain but do not provide age-appropriate, cell-type specific information. NEW METHOD We isolated specific cell types from adult murine brain using FACS to assess cell type-specific gene expression in conditional mouse models. RESULTS We identified robust but incomplete genetic knockdown in microglia isolated from two separate microglia-specific knockout models. COMPARISONWITH EXISTING METHODS(S) Genetic knockdown in isolated adult microglia differed significantly from cultured primary microglia. CONCLUSIONS Differences observed in primary cultured microglia compared to isolated adult microglia suggest that current methods used to validate microglia-specific gene deletion over-estimate deletion efficiency. Assessment of gene expression in isolated adult microglia provides a more accurate assessment of Cre-mediated gene deletion.
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Affiliation(s)
- Natalia Kosior
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia and Children's and Women's Hospital, 980 West 28thAvenue, Vancouver, BC, V5Z 4H4, Canada
| | - Terri L Petkau
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia and Children's and Women's Hospital, 980 West 28thAvenue, Vancouver, BC, V5Z 4H4, Canada
| | - Colúm Connolly
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia and Children's and Women's Hospital, 980 West 28thAvenue, Vancouver, BC, V5Z 4H4, Canada
| | - Ge Lu
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia and Children's and Women's Hospital, 980 West 28thAvenue, Vancouver, BC, V5Z 4H4, Canada
| | - Blair R Leavitt
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia and Children's and Women's Hospital, 980 West 28thAvenue, Vancouver, BC, V5Z 4H4, Canada; Division of Neurology, Department of Medicine, University of British Columbia Hospital, S 192-2211 Wesbrook Mall, Vancouver, BC, V6T 2B5, Canada; Brain Research Center, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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Carvalho TG, Alves-Silva J, de Souza JM, Real AL, Doria JG, Vieira EL, Gomes GF, de Oliveira AC, Miranda AS, Ribeiro FM. Metabotropic glutamate receptor 5 ablation accelerates age-related neurodegeneration and neuroinflammation. Neurochem Int 2019; 126:218-228. [DOI: 10.1016/j.neuint.2019.03.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/20/2019] [Accepted: 03/26/2019] [Indexed: 01/26/2023]
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