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Cao H, Li B, Mu M, Li S, Chen H, Tao H, Wang W, Zou Y, Zhao Y, Liu Y, Tao X. Nicotine suppresses crystalline silica-induced astrocyte activation and neuronal death by inhibiting NF-κB in the mouse hippocampus. CNS Neurosci Ther 2024; 30:e14508. [PMID: 37864452 PMCID: PMC11017465 DOI: 10.1111/cns.14508] [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: 06/22/2023] [Revised: 09/25/2023] [Accepted: 10/06/2023] [Indexed: 10/22/2023] Open
Abstract
AIMS Exposure to crystalline silica (CS) in occupational settings induces chronic inflammation in the respiratory system and, potentially, the brain. Some workers are frequently concurrently exposed to both CS and nicotine. Here, we explored the impact of nicotine on CS-induced neuroinflammation in the mouse hippocampus. METHODS In this study, we established double-exposed models of CS and nicotine in C57BL/6 mice. To assess depression-like behavior, experiments were conducted at 3, 6, and 9 weeks. Serum inflammatory factors were analyzed by ELISA. Hippocampus was collected for RNA sequencing analysis and examining the gene expression patterns linked to inflammation and cell death. Microglia and astrocyte activation and hippocampal neuronal death were assessed using immunohistochemistry and immunofluorescence staining. Western blotting was used to analyze the NF-κB expression level. RESULTS Mice exposed to CS for 3 weeks showed signs of depression. This was accompanied by elevated IL-6 in blood, destruction of the blood-brain barrier, and activation of astrocytes caused by an increased NF-κB expression in the CA1 area of the hippocampus. The elevated levels of astrocyte-derived Lcn2 and upregulated genes related to inflammation led to higher neuronal mortality. Moreover, nicotine mitigated the NF-κB expression, astrocyte activation, and neuronal death, thereby ameliorating the associated symptoms. CONCLUSION Silica exposure induces neuroinflammation and neuronal death in the mouse hippocampal CA1 region and depressive behavior. However, nicotine inhibits CS-induced neuroinflammation and neuronal apoptosis, alleviating depressive-like behaviors in mice.
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Affiliation(s)
- Hangbing Cao
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Bing Li
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Min Mu
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Shanshan Li
- School of PharmacyBengbu Medical CollegeBengbuChina
| | - Haoming Chen
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Huihui Tao
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Wenyang Wang
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Yuanjie Zou
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Yehong Zhao
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Yang Liu
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
| | - Xinrong Tao
- Key Laboratory of Industrial Dust Control and Occupational Health of the Ministry of EducationAnhui University of Science and TechnologyHuainanChina
- Key Laboratory of Industrial Dust Deep Reduction and Occupational Health and Safety of Anhui Higher Education InstitutesAnhui University of Science and TechnologyHuainanChina
- Anhui Province Engineering Laboratory of Occupational Health and SafetyAnhui University of Science and TechnologyHuainanChina
- School of Medicine, Department of Medical Frontier Experimental CenterAnhui University of Science and TechnologyHuainanChina
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Spiteri AG, Pilkington KR, Wishart CL, Macia L, King NJC. High-Dimensional Methods of Single-Cell Microglial Profiling to Enhance Understanding of Neuropathological Disease. Curr Protoc 2024; 4:e985. [PMID: 38439574 DOI: 10.1002/cpz1.985] [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] [Indexed: 03/06/2024]
Abstract
Microglia are the innate myeloid cells of the central nervous system (CNS) parenchyma, functionally implicated in almost every defined neuroinflammatory and neurodegenerative disorder. Current understanding of disease pathogenesis for many neuropathologies is limited and/or lacks reliable diagnostic markers, vaccines, and treatments. With the increasing aging of society and rise in neurogenerative diseases, improving our understanding of their pathogenesis is essential. Analysis of microglia from murine disease models provides an investigative tool to unravel disease processes. In many neuropathologies, bone-marrow-derived monocytes are recruited to the CNS, adopting a phenotype similar to that of microglia. This significantly confounds the accurate identification of cell-type-specific functions and downstream therapeutic targeting. The increased capacity to analyze more phenotypic markers using spectral-cytometry-based technologies allows improved separation of microglia from monocyte-derived cells. Full-spectrum profiling enables enhanced marker resolution, time-efficient analysis of >40 fluorescence parameters, and extraction of cellular autofluorescence parameters. Coupling this system with additional cytometric technologies, including cell sorting and high-parameter imaging, can improve the understanding of microglial phenotypes in disease. To this end, we provide detailed, step-by-step protocols for the analysis of murine brain tissue by high-parameter ex vivo cytometric analysis using the Aurora spectral cytometer (Cytek), including best practices for unmixing and autofluorescence extraction, cell sorting for single-cell RNA analysis, and imaging mass cytometry. Together, this provides a toolkit for researchers to comprehensively investigate microglial disease processes at protein, RNA, and spatial levels for the identification of therapeutic targets in neuropathology. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Processing the mouse brain into a single-cell suspension for microglia isolation Basic Protocol 2: Staining single-cell mouse brain suspensions for microglial phenotyping by spectral cytometry Basic Protocol 3: Flow cytometric sorting of mouse microglia for ex vivo analysis Basic Protocol 4: Processing the mouse brain for imaging mass cytometry for spatial microglia analysis.
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Affiliation(s)
- Alanna G Spiteri
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | | | - Claire L Wishart
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | - Laurence Macia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, Australia
| | - Nicholas J C King
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, Australia
- The University of Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, Australia
- The University of Sydney Nano Institute, The University of Sydney, Sydney, Australia
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3
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Kirschstein T, Köhling R. Functional changes in neuronal circuits due to antibody-driven autoimmune response. Neurobiol Dis 2023:106221. [PMID: 37414365 DOI: 10.1016/j.nbd.2023.106221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 06/26/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023] Open
Abstract
Autoimmune-mediated encephalitis syndromes are increasingly being recognized as important clinical entities. They need to be thought of as differential diagnosis in any patient presenting with fast-onset psychosis or psychiatric problems, memory deficits or other cognitive problems, including aphasias, as well as seizures or motor automatisms, but also rigidity, paresis, ataxia or dystonic / parkinsonian symptoms. Diagnosis including imaging and CSF search for antibodies needs to be fast, as progression of these inflammatory processes is often causing scarring of brain tissue, with hypergliosis and atrophy. As these symptoms show, the autoantibodies present in these cases appear to act within the CNS. Several of such antibodies have by now been identified such as IgG directed against NMDA-receptors, AMPA receptors, GABAA and GABAB receptors, and voltage gated potassium channels and proteins of the potassium channel complex (i.e. LGI1 and CASPR2). These are neuropil / surface antigens where antibody interaction can well be envisaged to cause dysfunction of the target protein, including internalization. Others, such as antibodies directed against GAD65 (an intracellular enzyme responsible for GABA-synthesis from glutamate), are discussed to constitute epiphenomena, but not causal agents in disease progression. This review will focus on the current knowledge of antibody interaction mechanisms, especially discussing cellular excitability changes and synaptic interactions in hippocampal and other brain networks. One challenge in this context is to find viable hypotheses for the emergence of both, hyperexcitability and seizures, and presumably reduced synaptic plasticity and underlying cognitive dysfunction.
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Affiliation(s)
- Timo Kirschstein
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Gertrudenstraße 9, 18057 Rostock, Germany; Center for Translational Neuroscience Research, Rostock University Medical Center, 18057 Rostock, Germany
| | - Rüdiger Köhling
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Gertrudenstraße 9, 18057 Rostock, Germany; Center for Translational Neuroscience Research, Rostock University Medical Center, 18057 Rostock, Germany.
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4
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Spiteri AG, Wishart CL, Ni D, Viengkhou B, Macia L, Hofer MJ, King NJC. Temporal tracking of microglial and monocyte single-cell transcriptomics in lethal flavivirus infection. Acta Neuropathol Commun 2023; 11:60. [PMID: 37016414 PMCID: PMC10074823 DOI: 10.1186/s40478-023-01547-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/08/2023] [Indexed: 04/06/2023] Open
Abstract
As the resident parenchymal myeloid population in the central nervous system (CNS), microglia are strategically positioned to respond to neurotropic virus invasion and have been implicated in promoting both disease resolution and progression in the acute and post-infectious phase of virus encephalitis. In a mouse model of West Nile virus encephalitis (WNE), infection of the CNS results in recruitment of large numbers of peripheral immune cells into the brain, the majority being nitric oxide (NO)-producing Ly6Chi inflammatory monocyte-derived cells (MCs). In this model, these cells enhance immunopathology and mortality. However, the contribution of microglia to this response is currently undefined. Here we used a combination of experimental tools, including single-cell RNA sequencing (scRNA-seq), microglia and MC depletion reagents, high-dimensional spectral cytometry and computational algorithms to dissect the differential contribution of microglia and MCs to the anti-viral immune response in severe neuroinflammation seen in WNE. Intriguingly, analysis of scRNA-seq data revealed 6 unique microglia and 3 unique MC clusters that were predominantly timepoint-specific, demonstrating substantial transcriptional adaptation with disease progression over the course of WNE. While microglia and MC adopted unique gene expression profiles, gene ontology enrichment analysis, coupled with microglia and MC depletion studies, demonstrated a role for both of these cells in the trafficking of peripheral immune cells into the CNS, T cell responses and viral clearance. Over the course of infection, microglia transitioned from a homeostatic to an anti-viral and then into an immune cell-recruiting phenotype. Conversely, MC adopted antigen-presenting, immune cell-recruiting and NO-producing phenotypes, which all had anti-viral function. Overall, this study defines for the first time the single-cell transcriptomic responses of microglia and MCs over the course of WNE, demonstrating both protective and pathological roles of these cells that could potentially be targeted for differential therapeutic intervention to dampen immune-mediated pathology, while maintaining viral clearance functions.
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Affiliation(s)
- Alanna G Spiteri
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia
- Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Claire L Wishart
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia
- Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Duan Ni
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- Chronic Diseases Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Barney Viengkhou
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Laurence Macia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- Chronic Diseases Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Markus J Hofer
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- The University of Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Nicholas J C King
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia.
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia.
- Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, 2006, Australia.
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia.
- The University of Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW, 2006, Australia.
- Sydney Nano, The University of Sydney, Sydney, NSW, 2006, Australia.
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Wu YG, Song LJ, Yin LJ, Yin JJ, Wang Q, Yu JZ, Xiao BG, Ma CG. The effects and potential of microglial polarization and crosstalk with other cells of the central nervous system in the treatment of Alzheimer's disease. Neural Regen Res 2022; 18:947-954. [PMID: 36254973 PMCID: PMC9827789 DOI: 10.4103/1673-5374.355747] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Microglia are resident immune cells in the central nervous system. During the pathogenesis of Alzheimer's disease, stimulatory factors continuously act on the microglia causing abnormal activation and unbalanced phenotypic changes; these events have become a significant and promising area of research. In this review, we summarize the effects of microglial polarization and crosstalk with other cells in the central nervous system in the treatment of Alzheimer's disease. Our literature search found that phenotypic changes occur continuously in Alzheimer's disease and that microglia exhibit extensive crosstalk with astrocytes, oligodendrocytes, neurons, and penetrated peripheral innate immune cells via specific signaling pathways and cytokines. Collectively, unlike previous efforts to modulate microglial phenotypes at a single level, targeting the phenotypes of microglia and the crosstalk with other cells in the central nervous system may be more effective in reducing inflammation in the central nervous system in Alzheimer's disease. This would establish a theoretical basis for reducing neuronal death from central nervous system inflammation and provide an appropriate environment to promote neuronal regeneration in the treatment of Alzheimer's disease.
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Affiliation(s)
- Yi-Ge Wu
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine/Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, Shanxi Province, China
| | - Li-Juan Song
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine/Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, Shanxi Province, China,Department of Physiology, Shanxi Medical University, Taiyuan, Shanxi Province, China
| | - Li-Jun Yin
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine/Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, Shanxi Province, China
| | - Jun-Jun Yin
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine/Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, Shanxi Province, China,Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China
| | - Qing Wang
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine/Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, Shanxi Province, China
| | - Jie-Zhong Yu
- Institute of Brain Science/Shanxi Key Laboratory of Inflammatory Neurodegenerative Diseases/Medical School, Shanxi Datong University, Datong, Shanxi Province, China
| | - Bao-Guo Xiao
- Institute of Neurology, Huashan Hospital, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Cun-Gen Ma
- The Key Research Laboratory of Benefiting Qi for Acting Blood Circulation Method to Treat Multiple Sclerosis of State Administration of Traditional Chinese Medicine/Research Center of Neurobiology, Shanxi University of Chinese Medicine, Jinzhong, Shanxi Province, China,Institute of Brain Science/Shanxi Key Laboratory of Inflammatory Neurodegenerative Diseases/Medical School, Shanxi Datong University, Datong, Shanxi Province, China,Correspondence to: Cun-Gen Ma, .
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Spiteri AG, Ni D, Ling ZL, Macia L, Campbell IL, Hofer MJ, King NJC. PLX5622 Reduces Disease Severity in Lethal CNS Infection by Off-Target Inhibition of Peripheral Inflammatory Monocyte Production. Front Immunol 2022; 13:851556. [PMID: 35401512 PMCID: PMC8990748 DOI: 10.3389/fimmu.2022.851556] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/03/2022] [Indexed: 11/18/2022] Open
Abstract
PLX5622 is a CSF-1R inhibitor and microglia-depleting reagent, widely used to investigate the biology of this central nervous system (CNS)-resident myeloid population, but the indirect or off-target effects of this agent remain largely unexplored. In a murine model of severe neuroinflammation induced by West Nile virus encephalitis (WNE), we showed PLX5622 efficiently depleted both microglia and a sub-population of border-associated macrophages in the CNS. However, PLX5622 also significantly depleted mature Ly6Chi monocytes in the bone marrow (BM), inhibiting their proliferation and lethal recruitment into the infected brain, reducing neuroinflammation and clinical disease scores. Notably, in addition, BM dendritic cell subsets, plasmacytoid DC and classical DC, were depleted differentially in infected and uninfected mice. Confirming its protective effect in WNE, cessation of PLX5622 treatment exacerbated disease scores and was associated with robust repopulation of microglia, rebound BM monopoiesis and markedly increased inflammatory monocyte infiltration into the CNS. Monoclonal anti-CSF-1R antibody blockade late in WNE also impeded BM monocyte proliferation and recruitment to the brain, suggesting that the protective effect of PLX5622 is via the inhibition of CSF-1R, rather than other kinase targets. Importantly, BrdU incorporation in PLX5622-treated mice, suggest remaining microglia proliferate independently of CSF-1 in WNE. Our study uncovers significantly broader effects of PLX5622 on the myeloid lineage beyond microglia depletion, advising caution in the interpretation of PLX5622 data as microglia-specific. However, this work also strikingly demonstrates the unexpected therapeutic potential of this molecule in CNS viral infection, as well as other monocyte-mediated diseases.
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Affiliation(s)
- Alanna G Spiteri
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
| | - Duan Ni
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.,Chronic Diseases Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Zheng Lung Ling
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
| | - Laurence Macia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.,Chronic Diseases Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Iain L Campbell
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Markus J Hofer
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia.,The University of Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW, Australia
| | - Nicholas J C King
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, NSW, Australia.,Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.,The University of Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW, Australia.,The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW, Australia
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Spiteri AG, Wishart CL, Pamphlett R, Locatelli G, King NJC. Microglia and monocytes in inflammatory CNS disease: integrating phenotype and function. Acta Neuropathol 2022; 143:179-224. [PMID: 34853891 PMCID: PMC8742818 DOI: 10.1007/s00401-021-02384-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/11/2021] [Accepted: 11/11/2021] [Indexed: 02/08/2023]
Abstract
In neurological diseases, the actions of microglia, the resident myeloid cells of the CNS parenchyma, may diverge from, or intersect with, those of recruited monocytes to drive immune-mediated pathology. However, defining the precise roles of each cell type has historically been impeded by the lack of discriminating markers and experimental systems capable of accurately identifying them. Our ability to distinguish microglia from monocytes in neuroinflammation has advanced with single-cell technologies, new markers and drugs that identify and deplete them, respectively. Nevertheless, the focus of individual studies on particular cell types, diseases or experimental approaches has limited our ability to connect phenotype and function more widely and across diverse CNS pathologies. Here, we critically review, tabulate and integrate the disease-specific functions and immune profiles of microglia and monocytes to provide a comprehensive atlas of myeloid responses in viral encephalitis, demyelination, neurodegeneration and ischemic injury. In emphasizing the differential roles of microglia and monocytes in the severe neuroinflammatory disease of viral encephalitis, we connect inflammatory pathways common to equally incapacitating diseases with less severe inflammation. We examine these findings in the context of human studies and highlight the benefits and inherent limitations of animal models that may impede or facilitate clinical translation. This enables us to highlight common and contrasting, non-redundant and often opposing roles of microglia and monocytes in disease that could be targeted therapeutically.
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Comparative Review of Microglia and Monocytes in CNS Phagocytosis. Cells 2021; 10:cells10102555. [PMID: 34685535 PMCID: PMC8534258 DOI: 10.3390/cells10102555] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 01/08/2023] Open
Abstract
Macrophages maintain tissue homeostasis by phagocytosing and removing unwanted materials such as dead cells and cell debris. Microglia, the resident macrophages of the central nervous system (CNS), are no exception. In addition, a series of recent studies have shown that microglia phagocytose the neuronal synapses that form the basis of neural circuit function. This discovery has spurred many neuroscientists to study microglia. Importantly, in the CNS parenchyma, not only microglia but also blood-derived monocytes, which essentially differentiate into macrophages after infiltration, exert phagocytic ability, making the study of phagocytosis in the CNS even more interesting and complex. In particular, in the diseased brain, the phagocytosis of tissue-damaging substances, such as myelin debris in multiple sclerosis (MS), has been shown to be carried out by both microglia and blood-derived monocytes. However, it remains largely unclear why blood-derived monocytes need to invade the parenchyma, where microglia are already abundant, to assist in phagocytosis. We will also discuss whether this phagocytosis can affect the fate of the phagocytosing cell itself as well as the substance being phagocytosed and the surrounding environment in addition to future research directions. In this review, we will introduce recent studies to answer a question that often arises when studying microglial phagocytosis: under what circumstances and to what extent blood-derived monocytes infiltrate the CNS and contribute to phagocytosis. In addition, the readers will learn how recent studies have experimentally distinguished between microglia and infiltrating monocytes. Finally, we aim to contribute to the progress of phagocytosis research by discussing the effects of phagocytosis on phagocytic cells.
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Spiteri AG, Terry RL, Wishart CL, Ashhurst TM, Campbell IL, Hofer MJ, King NJC. High-parameter cytometry unmasks microglial cell spatio-temporal response kinetics in severe neuroinflammatory disease. J Neuroinflammation 2021; 18:166. [PMID: 34311763 PMCID: PMC8314570 DOI: 10.1186/s12974-021-02214-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/07/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Differentiating infiltrating myeloid cells from resident microglia in neuroinflammatory disease is challenging, because bone marrow-derived inflammatory monocytes infiltrating the inflamed brain adopt a 'microglia-like' phenotype. This precludes the accurate identification of either cell type without genetic manipulation, which is important to understand their temporal contribution to disease and inform effective intervention in its pathogenesis. During West Nile virus (WNV) encephalitis, widespread neuronal infection drives substantial CNS infiltration of inflammatory monocytes, causing severe immunopathology and/or death, but the role of microglia in this remains unclear. METHODS Using high-parameter cytometry and dimensionality-reduction, we devised a simple, novel gating strategy to identify microglia and infiltrating myeloid cells during WNV-infection. Validating our strategy, we (1) blocked the entry of infiltrating myeloid populations from peripheral blood using monoclonal blocking antibodies, (2) adoptively transferred BM-derived monocytes and tracked their phenotypic changes after infiltration and (3) labelled peripheral leukocytes that infiltrate into the brain with an intravenous dye. We demonstrated that myeloid immigrants populated only the identified macrophage gates, while PLX5622 depletion reduced all 4 subsets defined by the microglial gates. RESULTS Using this gating approach, we identified four consistent microglia subsets in the homeostatic and WNV-infected brain. These were P2RY12hi CD86-, P2RY12hi CD86+ and P2RY12lo CD86- P2RY12lo CD86+. During infection, 2 further populations were identified as 'inflammatory' and 'microglia-like' macrophages, recruited from the bone marrow. Detailed kinetic analysis showed significant increases in the proportions of both P2RY12lo microglia subsets in all anatomical areas, largely at the expense of the P2RY12hi CD86- subset, with the latter undergoing compensatory proliferation, suggesting replenishment of, and differentiation from this subset in response to infection. Microglia altered their morphology early in infection, with all cells adopting temporal and regional disease-specific phenotypes. Late in disease, microglia produced IL-12, downregulated CX3CR1, F4/80 and TMEM119 and underwent apoptosis. Infiltrating macrophages expressed both TMEM119 and P2RY12 de novo, with the microglia-like subset notably exhibiting the highest proportional myeloid population death. CONCLUSIONS Our approach enables detailed kinetic analysis of resident vs infiltrating myeloid cells in a wide range of neuroinflammatory models without non-physiological manipulation. This will more clearly inform potential therapeutic approaches that specifically modulate these cells.
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Affiliation(s)
- Alanna G Spiteri
- Discipline of Pathology, Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | - Rachel L Terry
- Discipline of Pathology, Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Current Address: Children's Cancer Institute, Randwick, New South Wales, Australia
- Current Affiliation: Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Claire L Wishart
- Discipline of Pathology, Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | - Thomas M Ashhurst
- Discipline of Pathology, Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Sydney Cytometry Facility, The University of Sydney and Centenary Institute, Sydney, Australia
- Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity (MBI), Faculty of Medicine and Health, Sydney Medical School, The University of Sydney, Sydney, Australia
| | - Iain L Campbell
- Marie Bashir Institute for Infectious Diseases and Biosecurity (MBI), Faculty of Medicine and Health, Sydney Medical School, The University of Sydney, Sydney, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia
| | - Markus J Hofer
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity (MBI), Faculty of Medicine and Health, Sydney Medical School, The University of Sydney, Sydney, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia
| | - Nicholas J C King
- Discipline of Pathology, Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia.
- Charles Perkins Centre, The University of Sydney, Sydney, Australia.
- Sydney Cytometry Facility, The University of Sydney and Centenary Institute, Sydney, Australia.
- Ramaciotti Facility for Human Systems Biology, The University of Sydney and Centenary Institute, Sydney, Australia.
- Marie Bashir Institute for Infectious Diseases and Biosecurity (MBI), Faculty of Medicine and Health, Sydney Medical School, The University of Sydney, Sydney, Australia.
- Nano Institute, The University of Sydney, Sydney, Australia.
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