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Green TRF, Rowe RK. Quantifying microglial morphology: an insight into function. Clin Exp Immunol 2024; 216:221-229. [PMID: 38456795 PMCID: PMC11097915 DOI: 10.1093/cei/uxae023] [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: 08/09/2023] [Revised: 01/17/2024] [Accepted: 03/06/2024] [Indexed: 03/09/2024] Open
Abstract
Microglia are specialized immune cells unique to the central nervous system (CNS). Microglia have a highly plastic morphology that changes rapidly in response to injury or infection. Qualitative and quantitative measurements of ever-changing microglial morphology are considered a cornerstone of many microglia-centric research studies. The distinctive morphological variations seen in microglia are a useful marker of inflammation and severity of tissue damage. Although a wide array of damage-associated microglial morphologies has been documented, the exact functions of these distinct morphologies are not fully understood. In this review, we discuss how microglia morphology is not synonymous with microglia function, however, morphological outcomes can be used to make inferences about microglial function. For a comprehensive examination of the reactive status of a microglial cell, both histological and genetic approaches should be combined. However, the importance of quality immunohistochemistry-based analyses should not be overlooked as they can succinctly answer many research questions.
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Affiliation(s)
- Tabitha R F Green
- Department of Integrative Physiology, The University of Colorado Boulder, Boulder, CO, USA
| | - Rachel K Rowe
- Department of Integrative Physiology, The University of Colorado Boulder, Boulder, CO, USA
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Fan H, Zhang M, Wen J, Wang S, Yuan M, Sun H, Shu L, Yang X, Pu Y, Cai Z. Microglia in brain aging: An overview of recent basic science and clinical research developments. J Biomed Res 2024; 38:122-136. [PMID: 38403286 PMCID: PMC11001587 DOI: 10.7555/jbr.37.20220220] [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: 10/05/2022] [Revised: 12/25/2022] [Accepted: 01/12/2023] [Indexed: 02/27/2024] Open
Abstract
Aging is characterized by progressive degeneration of tissues and organs, and it is positively associated with an increased mortality rate. The brain, as one of the most significantly affected organs, experiences age-related changes, including abnormal neuronal activity, dysfunctional calcium homeostasis, dysregulated mitochondrial function, and increased levels of reactive oxygen species. These changes collectively contribute to cognitive deterioration. Aging is also a key risk factor for neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. For many years, neurodegenerative disease investigations have primarily focused on neurons, with less attention given to microglial cells. However, recently, microglial homeostasis has emerged as an important mediator in neurological disease pathogenesis. Here, we provide an overview of brain aging from the perspective of the microglia. In doing so, we present the current knowledge on the correlation between brain aging and the microglia, summarize recent progress of investigations about the microglia in normal aging, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, and then discuss the correlation between the senescent microglia and the brain, which will culminate with a presentation of the molecular complexity involved in the microglia in brain aging with suggestions for healthy aging.
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Affiliation(s)
- Haixia Fan
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
- Department of Neurology, the First Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Minheng Zhang
- Department of Gerontology, the First People's Hospital of Jinzhong, Jinzhong, Shanxi 030009, China
| | - Jie Wen
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Shengyuan Wang
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Minghao Yuan
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Houchao Sun
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Liu Shu
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Xu Yang
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Yinshuang Pu
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
| | - Zhiyou Cai
- Chongqing Medical University, Chongqing 400042, China
- Department of Neurology, Chongqing General Hospital, Chongqing 400013, China
- Chongqing Key Laboratory of Neurodegenerative Diseases, Chongqing 400013, China
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Bobotis BC, Halvorson T, Carrier M, Tremblay MÈ. Established and emerging techniques for the study of microglia: visualization, depletion, and fate mapping. Front Cell Neurosci 2024; 18:1317125. [PMID: 38425429 PMCID: PMC10902073 DOI: 10.3389/fncel.2024.1317125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/15/2024] [Indexed: 03/02/2024] Open
Abstract
The central nervous system (CNS) is an essential hub for neuronal communication. As a major component of the CNS, glial cells are vital in the maintenance and regulation of neuronal network dynamics. Research on microglia, the resident innate immune cells of the CNS, has advanced considerably in recent years, and our understanding of their diverse functions continues to grow. Microglia play critical roles in the formation and regulation of neuronal synapses, myelination, responses to injury, neurogenesis, inflammation, and many other physiological processes. In parallel with advances in microglial biology, cutting-edge techniques for the characterization of microglial properties have emerged with increasing depth and precision. Labeling tools and reporter models are important for the study of microglial morphology, ultrastructure, and dynamics, but also for microglial isolation, which is required to glean key phenotypic information through single-cell transcriptomics and other emerging approaches. Strategies for selective microglial depletion and modulation can provide novel insights into microglia-targeted treatment strategies in models of neuropsychiatric and neurodegenerative conditions, cancer, and autoimmunity. Finally, fate mapping has emerged as an important tool to answer fundamental questions about microglial biology, including their origin, migration, and proliferation throughout the lifetime of an organism. This review aims to provide a comprehensive discussion of these established and emerging techniques, with applications to the study of microglia in development, homeostasis, and CNS pathologies.
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Affiliation(s)
- Bianca Caroline Bobotis
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Centre for Advanced Materials and Related Technology, Victoria, BC, Canada
| | - Torin Halvorson
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada
- Department of Surgery, University of British Columbia, Vancouver, BC, Canada
- British Columbia Children’s Hospital Research Institute, Vancouver, BC, Canada
| | - Micaël Carrier
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Département de Psychiatrie et de Neurosciences, Faculté de Médecine, Université Laval, Québec City, QC, Canada
- Axe neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Centre for Advanced Materials and Related Technology, Victoria, BC, Canada
- Axe neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
- Department of Molecular Medicine, Université Laval, Québec City, QC, Canada
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Ago Y, Rintz E, Musini KS, Ma Z, Tomatsu S. Molecular Mechanisms in Pathophysiology of Mucopolysaccharidosis and Prospects for Innovative Therapy. Int J Mol Sci 2024; 25:1113. [PMID: 38256186 PMCID: PMC10816168 DOI: 10.3390/ijms25021113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
Mucopolysaccharidoses (MPSs) are a group of inborn errors of the metabolism caused by a deficiency in the lysosomal enzymes required to break down molecules called glycosaminoglycans (GAGs). These GAGs accumulate over time in various tissues and disrupt multiple biological systems, including catabolism of other substances, autophagy, and mitochondrial function. These pathological changes ultimately increase oxidative stress and activate innate immunity and inflammation. We have described the pathophysiology of MPS and activated inflammation in this paper, starting with accumulating the primary storage materials, GAGs. At the initial stage of GAG accumulation, affected tissues/cells are reversibly affected but progress irreversibly to: (1) disruption of substrate degradation with pathogenic changes in lysosomal function, (2) cellular dysfunction, secondary/tertiary accumulation (toxins such as GM2 or GM3 ganglioside, etc.), and inflammatory process, and (3) progressive tissue/organ damage and cell death (e.g., skeletal dysplasia, CNS impairment, etc.). For current and future treatment, several potential treatments for MPS that can penetrate the blood-brain barrier and bone have been proposed and/or are in clinical trials, including targeting peptides and molecular Trojan horses such as monoclonal antibodies attached to enzymes via receptor-mediated transport. Gene therapy trials with AAV, ex vivo LV, and Sleeping Beauty transposon system for MPS are proposed and/or underway as innovative therapeutic options. In addition, possible immunomodulatory reagents that can suppress MPS symptoms have been summarized in this review.
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Affiliation(s)
- Yasuhiko Ago
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA; (Y.A.); (K.S.M.); (Z.M.)
| | - Estera Rintz
- Department of Molecular Biology, Faculty of Biology, University of Gdansk, 80-308 Gdansk, Poland;
| | - Krishna Sai Musini
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA; (Y.A.); (K.S.M.); (Z.M.)
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Zhengyu Ma
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA; (Y.A.); (K.S.M.); (Z.M.)
| | - Shunji Tomatsu
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA; (Y.A.); (K.S.M.); (Z.M.)
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501-1112, Japan
- Department of Pediatrics, Thomas Jefferson University, Philadelphia, PA 19144, USA
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Müller L, Di Benedetto S. Aged brain and neuroimmune responses to COVID-19: post-acute sequelae and modulatory effects of behavioral and nutritional interventions. Immun Ageing 2023; 20:17. [PMID: 37046272 PMCID: PMC10090758 DOI: 10.1186/s12979-023-00341-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/03/2023] [Indexed: 04/14/2023]
Abstract
Advanced age is one of the significant risk determinants for coronavirus disease 2019 (COVID-19)-related mortality and for long COVID complications. The contributing factors may include the age-related dynamical remodeling of the immune system, known as immunosenescence and chronic low-grade systemic inflammation. Both of these factors may induce an inflammatory milieu in the aged brain and drive the changes in the microenvironment of neurons and microglia, which are characterized by a general condition of chronic inflammation, so-called neuroinflammation. Emerging evidence reveals that the immune privilege in the aging brain may be compromised. Resident brain cells, such as astrocytes, neurons, oligodendrocytes and microglia, but also infiltrating immune cells, such as monocytes, T cells and macrophages participate in the complex intercellular networks and multiple reciprocal interactions. Especially changes in microglia playing a regulatory role in inflammation, contribute to disturbing of the brain homeostasis and to impairments of the neuroimmune responses. Neuroinflammation may trigger structural damage, diminish regeneration, induce neuronal cell death, modulate synaptic remodeling and in this manner negatively interfere with the brain functions.In this review article, we give insights into neuroimmune interactions in the aged brain and highlight the impact of COVID-19 on the functional systems already modulated by immunosenescence and neuroinflammation. We discuss the potential ways of these interactions with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and review proposed neuroimmune mechanisms and biological factors that may contribute to the development of persisting long COVID conditions. We summarize the potential mechanisms responsible for long COVID, including inflammation, autoimmunity, direct virus-mediated cytotoxicity, hypercoagulation, mitochondrial failure, dysbiosis, and the reactivation of other persisting viruses, such as the Cytomegalovirus (CMV). Finally, we discuss the effects of various interventional options that can decrease the propagation of biological, physiological, and psychosocial stressors that are responsible for neuroimmune activation and which may inhibit the triggering of unbalanced inflammatory responses. We highlight the modulatory effects of bioactive nutritional compounds along with the multimodal benefits of behavioral interventions and moderate exercise, which can be applied as postinfectious interventions in order to improve brain health.
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Affiliation(s)
- Ludmila Müller
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Lentzeallee 94, 14195, Berlin, Germany.
| | - Svetlana Di Benedetto
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Lentzeallee 94, 14195, Berlin, Germany
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Yang P, Davidson JO, Zhou KQ, Wilson R, Wassink G, Prasad JD, Bennet L, Gunn AJ, Dean JM. Therapeutic Hypothermia Attenuates Cortical Interneuron Loss after Cerebral Ischemia in Near-Term Fetal Sheep. Int J Mol Sci 2023; 24:ijms24043706. [PMID: 36835117 PMCID: PMC9962824 DOI: 10.3390/ijms24043706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/26/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
Therapeutic hypothermia significantly improves outcomes after neonatal hypoxic-ischemic (HI) encephalopathy but is only partially protective. There is evidence that cortical inhibitory interneuron circuits are particularly vulnerable to HI and that loss of interneurons may be an important contributor to long-term neurological dysfunction in these infants. In the present study, we examined the hypothesis that the duration of hypothermia has differential effects on interneuron survival after HI. Near-term fetal sheep received sham ischemia or cerebral ischemia for 30 min, followed by cerebral hypothermia from 3 h after ischemia end and continued up to 48 h, 72 h, or 120 h recovery. Sheep were euthanized after 7 days for histology. Hypothermia up to 48 h recovery resulted in moderate neuroprotection of glutamate decarboxylase (GAD)+ and parvalbumin+ interneurons but did not improve survival of calbindin+ cells. Hypothermia up to 72 h recovery was associated with significantly increased survival of all three interneuron phenotypes compared with sham controls. By contrast, while hypothermia up to 120 h recovery did not further improve (or impair) GAD+ or parvalbumin+ neuronal survival compared with hypothermia up to 72 h, it was associated with decreased survival of calbindin+ interneurons. Finally, protection of parvalbumin+ and GAD+ interneurons, but not calbindin+ interneurons, with hypothermia was associated with improved recovery of electroencephalographic (EEG) power and frequency by day 7 after HI. The present study demonstrates differential effects of increasing the duration of hypothermia on interneuron survival after HI in near-term fetal sheep. These findings may contribute to the apparent preclinical and clinical lack of benefit of very prolonged hypothermia.
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Xia M, Zhang Y, Wu H, Zhang Q, Liu Q, Li G, Zhao T, Liu X, Zheng S, Qian Z, Li H. Forsythoside B attenuates neuro-inflammation and neuronal apoptosis by inhibition of NF-κB and p38-MAPK signaling pathways through activating Nrf2 post spinal cord injury. Int Immunopharmacol 2022; 111:109120. [PMID: 35944463 DOI: 10.1016/j.intimp.2022.109120] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/30/2022] [Accepted: 07/30/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Spinal cord injury (SCI) is a ruinous neurological pathology that results in locomotor and sensory impairment. Neuro-inflammation and secondary neuronal apoptosis contribute to SCI, with anti-inflammatory therapies the focus of many SCI studies. Forsythoside B (FTS•B), a phenylethanoid glycoside extracted from the leaves of Lamiophlomis rotata Kudo, has been shown previously to have anti-inflammatory properties. Nevertheless, the therapeutic effect of FTS•B on neuro-inflammation after SCI is unknown. METHODS Neuro-inflammation was assessed by western blotting (WB), immunofluorescence (IF) staining, and enzyme-linked immunosorbent assay (ELISA) both in vitro and in vivo. Secondary neuronal apoptosis was simulated in a microglia-neuron co-culture model with the degree of apoptosis measured by WB, IF, and TUNEL staining. In vivo, FTS•B (10 mg/kg, 40 mg/kg) were intraperitoneally injected into SCI mice. Morphological changes following SCI were evaluated by Nissl, Hematoxylin-eosin, and Luxol Fast Blue staining. Basso Mouse Scale scores were used to evaluate locomotor function recovery. RESULTS FTS•B markedly decreased the levels of iNOS, COX-2 and signature mediators of inflammation. Phosphorylated p38 and nuclear factor-kappa B (NF-κB) were markedly decreased by FTS•B. Additionally, FTS•B-induced inhibition of NF-κB and p38-MAPK signaling pathways was reversed by Nrf2 downregulation. Administration of FTS•B also significantly reduced apoptosis-related protein levels indicating that FTS•B ameliorated secondary neuronal apoptosis. FTS•B administration inhibited glial scar formation, decreased neuronal death, tissue deficiency, alleviated demyelination, and promoted locomotor recovery. CONCLUSION FTS•B effectively attenuates neuro-inflammation and secondary neuronal apoptosis by inhibition of NF-κB and p38-MAPK signaling pathways through activating Nrf2 after SCI. This study demonstrates FTS•B to be a potential therapeutic for SCI.
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Affiliation(s)
- Mingjie Xia
- Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yanan Zhang
- Postgraduate School, Dalian Medical University, Dalian, China
| | - Honghui Wu
- Postgraduate School, Dalian Medical University, Dalian, China
| | - Qinyang Zhang
- Postgraduate School, Dalian Medical University, Dalian, China
| | - Qiangxian Liu
- Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Guangshen Li
- School of Medicine, Nantong University, Nantong, China
| | - Tianyu Zhao
- Postgraduate School, Dalian Medical University, Dalian, China
| | - Xuepeng Liu
- School of Medicine, Nantong University, Nantong, China
| | - Shengnai Zheng
- Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.
| | - Zhanyang Qian
- School of Medicine, Southeast University, Nanjing, China; Spine Center, Zhongda Hospital of Southeast University, Nanjing, China.
| | - Haijun Li
- Department of Orthopedics, Taizhou People's Hospital Affiliated to Nanjing Medical University, Taizhou, China; Taizhou Clinical Medical School of Nanjing Medical University, Taizhou, China.
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