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Braga JD, Komaru T, Umino M, Nagao T, Matsubara K, Egusa A, Yanaka N, Nishimura T, Kumrungsee T. Histidine-containing dipeptide deficiency links to hyperactivity and depression-like behaviors in old female mice. Biochem Biophys Res Commun 2024; 729:150361. [PMID: 38972141 DOI: 10.1016/j.bbrc.2024.150361] [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: 04/01/2024] [Revised: 05/28/2024] [Accepted: 07/04/2024] [Indexed: 07/09/2024]
Abstract
Carnosine, anserine, and homocarnosine are histidine-containing dipeptides (HCDs) abundant in the skeletal muscle and nervous system in mammals. To date, studies have extensively demonstrated effects of carnosine and anserine, the predominant muscular HCDs, on muscular functions and exercise performance. However, homocarnosine, the predominant brain HCD, is underexplored. Moreover, roles of homocarnosine and its related HCDs in the brain and behaviors remain poorly understood. Here, we investigated potential roles of endogenous brain homocarnosine and its related HCDs in behaviors by using carnosine synthase-1-deficient (Carns1-/-) mice. We found that old Carns1-/- mice (female 12 months old) exhibited hyperactivity- and depression-like behaviors with higher plasma corticosterone levels on light-dark transition and forced swimming tests, but had no defects in spontaneous locomotor activity, repetitive behavior, olfactory functions, and learning and memory abilities, as compared with their age-matched wild-type (WT) mice. We confirmed that homocarnosine and its related HCDs were deficient across brain areas of Carns1-/- mice. Homocarnosine deficiency exhibited small effects on its constituent γ-aminobutyric acid (GABA) in the brain, in which GABA levels in hypothalamus and olfactory bulb were higher in Carns1-/- mice than in WT mice. In WT mice, homocarnosine and GABA were highly present in hypothalamus, thalamus, and olfactory bulb, and their brain levels did not decrease in old mice when compared with younger mice (3 months old). Our present findings provide new insights into roles of homocarnosine and its related HCDs in behaviors and neurological disorders.
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Affiliation(s)
- Jason D Braga
- Program of Food and AgriLife Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8527, Japan; Institute of Food Science and Technology, College of Agriculture, Food, Environment and Natural Resources, Cavite State University, Indang, Cavite, 4122, Philippines
| | - Takumi Komaru
- Program of Food and AgriLife Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8527, Japan
| | - Mitsuki Umino
- Department of Human Life Science Education, Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, 739-8527, Japan
| | - Tomoka Nagao
- Program of Food and AgriLife Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8527, Japan
| | - Kiminori Matsubara
- Department of Human Life Science Education, Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, 739-8527, Japan
| | - Ai Egusa
- Department of Food Science and Technology, Nippon Veterinary and Life Science University, Tokyo, 180-8602, Japan
| | - Noriyuki Yanaka
- Program of Food and AgriLife Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8527, Japan
| | - Toshihide Nishimura
- Department of Food Nutrition, Kagawa Nutrition University, Saitama, 350-0214, Japan
| | - Thanutchaporn Kumrungsee
- Program of Food and AgriLife Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8527, Japan; Smart Agriculture, Graduate School of Innovation and Practice for Smart Society, Hiroshima University, Hiroshima, 739-8527, Japan.
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Früholz I, Meyer-Luehmann M. The intricate interplay between microglia and adult neurogenesis in Alzheimer's disease. Front Cell Neurosci 2024; 18:1456253. [PMID: 39360265 PMCID: PMC11445663 DOI: 10.3389/fncel.2024.1456253] [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: 06/28/2024] [Accepted: 08/26/2024] [Indexed: 10/04/2024] Open
Abstract
Microglia, the resident immune cells of the central nervous system, play a crucial role in regulating adult neurogenesis and contribute significantly to the pathogenesis of Alzheimer's disease (AD). Under physiological conditions, microglia support and modulate neurogenesis through the secretion of neurotrophic factors, phagocytosis of apoptotic cells, and synaptic pruning, thereby promoting the proliferation, differentiation, and survival of neural progenitor cells (NPCs). However, in AD, microglial function becomes dysregulated, leading to chronic neuroinflammation and impaired neurogenesis. This review explores the intricate interplay between microglia and adult neurogenesis in health and AD, synthesizing recent findings to provide a comprehensive overview of the current understanding of microglia-mediated regulation of adult neurogenesis. Furthermore, it highlights the potential of microglia-targeted therapies to modulate neurogenesis and offers insights into potential avenues for developing novel therapeutic interventions.
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Affiliation(s)
- Iris Früholz
- Department of Neurology, Medical Center ˗ University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Melanie Meyer-Luehmann
- Department of Neurology, Medical Center ˗ University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Tang X, Walter E, Wohleb E, Fan Y, Wang C. ATG5 (autophagy related 5) in microglia controls hippocampal neurogenesis in Alzheimer disease. Autophagy 2024; 20:847-862. [PMID: 37915255 PMCID: PMC11062374 DOI: 10.1080/15548627.2023.2277634] [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: 08/28/2023] [Accepted: 10/26/2023] [Indexed: 11/03/2023] Open
Abstract
Macroautophagy/autophagy is the intracellular degradation process of cytoplasmic content and damaged organelles. Autophagy is strongly associated with the progression of Alzheimer disease (AD). Microglia are brain-resident macrophages, and recent studies indicate that autophagy in microglia protects neurons from neurodegeneration. Postnatal neurogenesis, the generation of new neurons from adult neural stem cells (NSCs), is impaired in AD patients as well as in AD animal models. However, the extent to which microglial autophagy influences adult NSCs and neurogenesis in AD animal models has not been studied. Here, we showed that conditional knock out (cKO) of Atg5 (autophagy related 5) in microglia inhibited postnatal neurogenesis in the dentate gyrus (DG) of the hippocampus, but not in the subventricular zone (SVZ) of a 5×FAD mouse model. Interestingly, the protection of neurogenesis by Atg5 in microglia was only observed in female AD mice. To confirm the roles of autophagy in microglia for postnatal hippocampal neurogenesis, we generated additional cKO mice to delete autophagy essential genes Rb1cc1 or Atg14 in microglia. However, these rb1cc1 cKO and atg14 cKO mice did not exhibit neurogenesis defects in the context of a female AD mouse model. Last, we used the CSF1R antagonist to deplete ATG5-deficient microglia and this intervention restored neurogenesis in the hippocampus of 5×FAD mice. These results indicate that microglial ATG5 is essential to maintain postnatal hippocampal neurogenesis in a mouse model of AD. Our findings further support the notion that ATG5 in microglia supports NSC health and may prevent neurodegeneration.Abbreviations: 5×FAD: familial Alzheimer disease; Aβ: β-amyloid; AD: Alzheimer disease; AIF1: allograft inflammatory factor 1; ATG: autophagy related; BrdU: 5-bromo-2'-deoxyuridine; CA: Cornu Ammonis; cKO: conditional knock out; CSF1R: colony stimulating factor 1 receptor; Ctrl: control; DCX: doublecortin; DG: dentate gyrus; GFAP: glial fibrillary acidic protein; GZ: granular zone; H&E: hematoxylin and eosin; IF: immunofluorescence; LD: lipid droplet; LDAM: lipid droplets accumulated microglia; LPS: lipopolysaccharides; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; NSCs: neural stem cells; RB1CC1: RB1-inducible coiled-coil 1; SOX2: SRY (sex determining region Y)-box 2; SGZ: subgranular zone; SVZ: subventricular zone; WT: wild type.
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Affiliation(s)
- Xin Tang
- Department of Cancer Biology, University of Cincinnati College Medicine, Cincinnati, OH, USA
| | - Ellen Walter
- Department of Cancer Biology, University of Cincinnati College Medicine, Cincinnati, OH, USA
| | - Eric Wohleb
- Department of Pharmacology & Systems Physiology, University of Cincinnati College Medicine, Cincinnati, OH, USA
| | - Yanbo Fan
- Department of Cancer Biology, University of Cincinnati College Medicine, Cincinnati, OH, USA
| | - Chenran Wang
- Department of Cancer Biology, University of Cincinnati College Medicine, Cincinnati, OH, USA
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Okano Y, Kase Y, Suematsu Y, Nakamura M, Okano H. Chronological transitions of hepatocyte growth factor treatment effects in spinal cord injury tissue. Inflamm Regen 2024; 44:10. [PMID: 38475915 DOI: 10.1186/s41232-024-00322-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 02/12/2024] [Indexed: 03/14/2024] Open
Abstract
Inflammatory responses are known to suppress neural regeneration in patients receiving stem cell-based regenerative therapy for spinal cord injury (SCI). Consequently, pathways involved in neurogenesis and immunomodulation, such as the hepatocyte growth factor (HGF)/MET signaling cascade, have garnered significant attention. Notably, various studies, including our own, have highlighted the enhanced recovery of locomotor functions achieved in SCI animal models by combining HGF pretreatment and human induced stem cell-derived neural stem/progenitor cell (hiPSC-NS/PC) transplantation. However, these studies implicitly hypothesized that the functionality of HGF in SCI would be time consistent and did not elucidate its dynamics. In the present article, we investigated the time-course of the effect of HGF on SCI, aiming to uncover a more precise mechanism for HGF administration, which is indispensable for developing crystallizing protocols for combination therapy. To this end, we performed a detailed investigation of the temporal variation of HGF using the RNA-seq data we obtained in our most recent study. Leveraging the time-series design of the data, which we did not fully exploit previously, we identified three components in the effects of HGF that operate at different times: early effects, continuous effects, and delayed effects. Our findings suggested a concept where the three components together contribute to the acceleration of neurogenesis and immunomodulation, which reinforce the legitimacy of empirically fine-tuned protocols for HGF administration and advocate the novel possibility that the time-inconsistent effects of HGF progressively augment the efficacy of combined therapy.
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Affiliation(s)
- Yuji Okano
- Department of Physiology, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan
- Department of Extended Intelligence for Medicine, The Ishii-Ishibashi Laboratory, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan
- Division of CNS Regeneration and Drug Discovery, International Center for Brain Science (ICBS), Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake-Shi, Aichi, 470-1192, Japan
| | - Yoshitaka Kase
- Department of Physiology, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan
- Division of CNS Regeneration and Drug Discovery, International Center for Brain Science (ICBS), Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake-Shi, Aichi, 470-1192, Japan
| | - Yu Suematsu
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan
| | - Masaya Nakamura
- Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan.
- Division of CNS Regeneration and Drug Discovery, International Center for Brain Science (ICBS), Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake-Shi, Aichi, 470-1192, Japan.
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Šimončičová E, Henderson Pekarik K, Vecchiarelli HA, Lauro C, Maggi L, Tremblay MÈ. Adult Neurogenesis, Learning and Memory. ADVANCES IN NEUROBIOLOGY 2024; 37:221-242. [PMID: 39207695 DOI: 10.1007/978-3-031-55529-9_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Neural plasticity can be defined as the ability of neural circuits to be shaped by external and internal factors. It provides the brain with a capacity for functional and morphological remodelling, with many lines of evidence indicating that these changes are vital for learning and memory formation. The basis of this brain plasticity resides in activity- and experience-driven modifications of synaptic strength, including synaptic formation, elimination or weakening, as well as of modulation of neuronal population, which drive the structural reorganization of neural networks. Recent evidence indicates that brain-resident glial cells actively participate in these processes, suggesting that mechanisms underlying plasticity in the brain are multifaceted. Establishing the 'tripartite' synapse, the role of astrocytes in modulating synaptic transmission in response to neuronal activity was recognized first. Further redefinition of the synapse as 'quad-partite' followed to acknowledge the contribution of microglia which were revealed to affect numerous brain functions via dynamic interactions with synapses, acting as 'synaptic sensors' that respond to neuronal activity and neurotransmitter release, as well as crosstalk with astrocytes. Early studies identified microglial ability to dynamically survey their local brain environment and established their integral role in the active interfacing of environmental stimuli (both internal and external), with brain plasticity and remodelling. Following the introduction to neurogenesis, this chapter details the role that microglia play in regulating neurogenesis in adulthood, specifically as it relates to learning and memory, as well as factors involved in modulation of microglia. Further, a microglial perspective is introduced for the context of environmental enrichment impact on neurogenesis, learning and memory across states of stress, ageing, disease and injury.
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Affiliation(s)
- Eva Šimončičová
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | | | | | - Clotilde Lauro
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Laura Maggi
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada.
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Choi SH, Tanzi RE. Adult neurogenesis in Alzheimer's disease. Hippocampus 2023; 33:307-321. [PMID: 36748337 DOI: 10.1002/hipo.23504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/08/2023] [Accepted: 01/11/2023] [Indexed: 02/08/2023]
Abstract
Alzheimer's disease (AD) is the most common form of age-related dementia, characterized by progressive memory loss and cognitive disturbances. The hippocampus, where adult hippocampal neurogenesis (AHN), a relatively novel form of brain plasticity that refers to the birth of new neurons, occurs, is one of the first brain regions to be affected in AD patients. Recent studies showed that AHN persists throughout life in humans, but it drops sharply in AD patients. Next questions to consider would be whether AHN impairment is a contributing factor to learning and memory impairment in AD and whether restoring AHN could ameliorate or delay cognitive dysfunction. Here, we outline and discuss the current knowledge about the state of AHN in AD patients, AHN impairment as a potentially relevant mechanism underlying memory deficits in AD, therapeutic potential of activating AHN in AD, and the mechanisms of AHN impairment in AD.
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Affiliation(s)
- Se Hoon Choi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
- McCance Center for Brain Health, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Rudolph E Tanzi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
- McCance Center for Brain Health, Massachusetts General Hospital, Boston, Massachusetts, USA
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7
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Pan WT, Liu PM, Ma D, Yang JJ. Advances in photobiomodulation for cognitive improvement by near-infrared derived multiple strategies. J Transl Med 2023; 21:135. [PMID: 36814278 PMCID: PMC9945713 DOI: 10.1186/s12967-023-03988-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 02/14/2023] [Indexed: 02/24/2023] Open
Abstract
Cognitive function is an important ability of the brain, but cognitive dysfunction can easily develop once the brain is injured in various neuropathological conditions or diseases. Photobiomodulation therapy is a type of noninvasive physical therapy that is gradually emerging in the field of neuroscience. Transcranial photobiomodulation has been commonly used to regulate neural activity in the superficial cortex. To stimulate deeper brain activity, advanced photobiomodulation techniques in conjunction with photosensitive nanoparticles have been developed. This review addresses the mechanisms of photobiomodulation on neurons and neural networks and discusses the advantages, disadvantages and potential applications of photobiomodulation alone or in combination with photosensitive nanoparticles. Photobiomodulation and its associated strategies may provide new breakthrough treatments for cognitive improvement.
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Affiliation(s)
- Wei-tong Pan
- grid.412633.10000 0004 1799 0733Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 China ,grid.207374.50000 0001 2189 3846Neuroscience Research Institute, Zhengzhou University Academy of Medical Sciences, Zhengzhou, 450052 China ,Henan Province International Joint Laboratory of Pain, Cognition and Emotion, Zhengzhou, 450000 People’s Republic of China
| | - Pan-miao Liu
- grid.412633.10000 0004 1799 0733Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 China ,grid.207374.50000 0001 2189 3846Neuroscience Research Institute, Zhengzhou University Academy of Medical Sciences, Zhengzhou, 450052 China ,Henan Province International Joint Laboratory of Pain, Cognition and Emotion, Zhengzhou, 450000 People’s Republic of China
| | - Daqing Ma
- Division of Anaesthetics, Pain Medicine & Intensive Care, Department of Surgery & Cancer, Faculty of Medicine, Imperial College London, Chelsea & Westminster Hospital, London, UK. .,National Clinical Research Center for Child Health, Hangzhou, 310052, China.
| | - Jian-jun Yang
- grid.412633.10000 0004 1799 0733Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 China ,grid.207374.50000 0001 2189 3846Neuroscience Research Institute, Zhengzhou University Academy of Medical Sciences, Zhengzhou, 450052 China ,Henan Province International Joint Laboratory of Pain, Cognition and Emotion, Zhengzhou, 450000 People’s Republic of China
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Salta E, Lazarov O, Fitzsimons CP, Tanzi R, Lucassen PJ, Choi SH. Adult hippocampal neurogenesis in Alzheimer's disease: A roadmap to clinical relevance. Cell Stem Cell 2023; 30:120-136. [PMID: 36736288 PMCID: PMC10082636 DOI: 10.1016/j.stem.2023.01.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 02/05/2023]
Abstract
Adult hippocampal neurogenesis (AHN) drops sharply during early stages of Alzheimer's disease (AD), via unknown mechanisms, and correlates with cognitive status in AD patients. Understanding AHN regulation in AD could provide a framework for innovative pharmacological interventions. We here combine molecular, behavioral, and clinical data and critically discuss the multicellular complexity of the AHN niche in relation to AD pathophysiology. We further present a roadmap toward a better understanding of the role of AHN in AD by probing the promises and caveats of the latest technological advancements in the field and addressing the conceptual and methodological challenges ahead.
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Affiliation(s)
- Evgenia Salta
- Laboratory of Neurogenesis and Neurodegeneration, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands
| | - Orly Lazarov
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois at Chicago, 808 S Wood St., Chicago, IL 60612, USA
| | - Carlos P Fitzsimons
- Brain Plasticity group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Rudolph Tanzi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, McCance Center for Brain Health, 114 16th Street, Boston, MA 02129, USA.
| | - Paul J Lucassen
- Brain Plasticity group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands; Center for Urban Mental Health, University of Amsterdam, Kruislaan 404, 1098 SM, Amsterdam, The Netherlands.
| | - Se Hoon Choi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, McCance Center for Brain Health, 114 16th Street, Boston, MA 02129, USA.
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9
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Sah A, Rooney S, Kharitonova M, Sartori SB, Wolf SA, Singewald N. Enriched Environment Attenuates Enhanced Trait Anxiety in Association with Normalization of Aberrant Neuro-Inflammatory Events. Int J Mol Sci 2022; 23:13052. [PMID: 36361832 PMCID: PMC9657487 DOI: 10.3390/ijms232113052] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/14/2022] [Accepted: 10/20/2022] [Indexed: 11/22/2022] Open
Abstract
Neuroinflammation is discussed to play a role in specific subgroups of different psychiatric disorders, including anxiety disorders. We have previously shown that a mouse model of trait anxiety (HAB) displays enhanced microglial density and phagocytic activity in key regions of anxiety circuits compared to normal-anxiety controls (NAB). Using minocycline, we provided causal evidence that reducing microglial activation within the dentate gyrus (DG) attenuated enhanced anxiety in HABs. Besides pharmacological intervention, "positive environmental stimuli", which have the advantage of exerting no side-effects, have been shown to modulate inflammation-related markers in human beings. Therefore, we now investigated whether environmental enrichment (EE) would be sufficient to modulate upregulated neuroinflammation in high-anxiety HABs. We show for the first time that EE can indeed attenuate enhanced trait anxiety, even when presented as late as adulthood. We further found that EE-induced anxiolysis was associated with the attenuation of enhanced microglial density (using Iba-1 as the marker) in the DG and medial prefrontal cortex. Additionally, EE reduced Iba1 + CD68+ microglia density within the anterior DG. Hence, the successful attenuation of trait anxiety by EE was associated in part with the normalization of neuro-inflammatory imbalances. These results suggest that pharmacological and/or positive behavioral therapies triggering microglia-targeted anti-inflammatory effects could be promising as novel alternatives or complimentary anxiolytic therapeutic approaches in specific subgroups of individuals predisposed to trait anxiety.
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Affiliation(s)
- Anupam Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82/III, A-6020 Innsbruck, Austria
| | - Sinead Rooney
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82/III, A-6020 Innsbruck, Austria
| | - Maria Kharitonova
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82/III, A-6020 Innsbruck, Austria
| | - Simone B. Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82/III, A-6020 Innsbruck, Austria
| | - Susanne A. Wolf
- Cellular Neurocience, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
- Department of Experimental Ophthalmology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82/III, A-6020 Innsbruck, Austria
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Altered corticostriatal synchronization associated with compulsive-like behavior in APP/PS1 mice. Exp Neurol 2021; 344:113805. [PMID: 34242631 DOI: 10.1016/j.expneurol.2021.113805] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 04/17/2021] [Accepted: 07/02/2021] [Indexed: 11/22/2022]
Abstract
Mild behavioral impairment (MBI), which can include compulsive behavior, is an early sign of Alzheimer's disease (AD), but its underlying neural mechanisms remain unclear. Here, we show that 3-5-month-old APP/PS1 mice display obsessive-compulsive disorder (OCD)-like behavior. The number of parvalbumin-positive (PV) interneurons and level of high gamma (γhigh) oscillation are significantly decreased in the striatum of AD mice. This is accompanied by enhanced β-γhigh coupling and firing rates of putative striatal projection neurons (SPNs), indicating decorrelation between PV interneurons and SPNs. Local field potentials (LFPs) simultaneously recorded in prefrontal cortex (PFC) and striatum (Str) demonstrate a decrease in γhigh-band coherent activity and spike-field coherence in corticostriatal circuits of APP/PS1 mice. Furthermore, levels of GABAB receptor (GABABR), but not GABAA receptor (GABAAR), and glutamatergic receptors, were markedly reduced, in line with presymptomatic AD-related behavioral changes. These findings suggest that MBI occurs as early as 3-5 months in APP/PS1 mice and that altered corticostriatal synchronization may play a role in mediating the behavioral phenotypes observed.
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11
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Sita G, Graziosi A, Hrelia P, Morroni F. NLRP3 and Infections: β-Amyloid in Inflammasome beyond Neurodegeneration. Int J Mol Sci 2021; 22:ijms22136984. [PMID: 34209586 PMCID: PMC8268482 DOI: 10.3390/ijms22136984] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 06/18/2021] [Accepted: 06/25/2021] [Indexed: 12/11/2022] Open
Abstract
Amyloid beta (Aβ)-induced abnormal neuroinflammation is recognized as a major pathological feature of Alzheimer’s disease (AD), which results in memory impairment. Research exploring low-grade systemic inflammation and its impact on the development and progression of neurodegenerative disease has increased. A particular research focus has been whether systemic inflammation arises only as a secondary effect of disease, or it is also a cause of pathology. The inflammasomes, and more specifically the NLRP3 inflammasome, are crucial components of the innate immune system and are usually activated in response to infection or tissue damage. Although inflammasome activation plays critical roles against various pathogens in host defense, overactivation of inflammasome contributes to the pathogenesis of inflammatory diseases, including acute central nervous system (CNS) injuries and chronic neurodegenerative diseases, such as AD. This review summarizes the current literature on the role of the NLRP3 inflammasome in the pathogenesis of AD, and its involvement in infections, particularly SARS-CoV-2. NLRP3 might represent the crossroad between the hypothesized neurodegeneration and the primary COVID-19 infection.
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12
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The interplay of neurovasculature and adult hippocampal neurogenesis. Neurosci Lett 2021; 760:136071. [PMID: 34147540 DOI: 10.1016/j.neulet.2021.136071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 05/06/2021] [Accepted: 06/15/2021] [Indexed: 01/14/2023]
Abstract
The subgranular zone of the dentate gyrus provides a local microenvironment (niche) for neural stem cells. In the adult brain, it has been established that the vascular compartment of such niches has a significant role in regulating adult hippocampal neurogenesis. More recently, evidence showed that neurovascular coupling, the relationship between blood flow and neuronal activity, also regulates hippocampal neurogenesis. Here, we review the most recent articles on addressing the intricate relationship between neurovasculature and adult hippocampal neurogenesis and a novel pathway where functional hyperemia enhances hippocampal neurogenesis. In the end, we have further reviewed recent research showing that impaired neurovascular coupling may cause declined neurogenesis and contribute to brain damage in neurodegenerative diseases.
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Macrophages and Stem Cells-Two to Tango for Tissue Repair? Biomolecules 2021; 11:biom11050697. [PMID: 34066618 PMCID: PMC8148606 DOI: 10.3390/biom11050697] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 04/26/2021] [Accepted: 05/04/2021] [Indexed: 12/25/2022] Open
Abstract
Macrophages (MCs) are present in all tissues, not only supporting homeostasis, but also playing an important role in organogenesis, post-injury regeneration, and diseases. They are a heterogeneous cell population due to their origin, tissue specificity, and polarization in response to aggression factors, depending on environmental cues. Thus, as pro-inflammatory M1 phagocytic MCs, they contribute to tissue damage and even fibrosis, but the anti-inflammatory M2 phenotype participates in repairing processes and wound healing through a molecular interplay with most cells in adult stem cell niches. In this review, we emphasize MC phenotypic heterogeneity in health and disease, highlighting their systemic and systematic contribution to tissue homeostasis and repair. Unraveling the intervention of both resident and migrated MCs on the behavior of stem cells and the regulation of the stem cell niche is crucial for opening new perspectives for novel therapeutic strategies in different diseases.
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14
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Liu H, Zhang H, Ma Y. Molecular mechanisms of altered adult hippocampal neurogenesis in Alzheimer's disease. Mech Ageing Dev 2021; 195:111452. [PMID: 33556365 DOI: 10.1016/j.mad.2021.111452] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 01/23/2021] [Accepted: 01/25/2021] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia globally. AD is a progressive neurodegenerative disorder, eventually manifesting as severe cognitive impairment. Adult hippocampal neurogenesis (AHN) occurs throughout adulthood and plays an important role in hippocampus-dependent learning and memory. The stages of AHN, predominantly comprising the proliferation, differentiation, survival, and maturation of newborn neurons, are affected to varying degrees in AD. However, the exact molecular mechanisms remain to be elucidated. Recent evidence suggests that the molecules involved in AD pathology contribute to the compromised AHN in AD. Notably, various interventions may have common signaling pathways that, once identified, could be harnessed to enhance adult neurogenesis. This in turn could putatively rescue cognitive deficits associated with impaired neurogenesis as observed in animal models of AD. In this manuscript, we review the current knowledge concerning AHN under normal physiological and AD pathological conditions and highlight the possible role of specific molecules in AHN alteration in AD. In addition, we summarize in vivo experiments with emphasis on the effect of the activation of certain key signalings on AHN in AD rodent models. We propose that these signaling targets and corresponding interventions should be considered when developing novel therapies for AD.
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Affiliation(s)
- Hang Liu
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, PR China
| | - Han Zhang
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, PR China
| | - Ying Ma
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, PR China.
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15
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Graykowski D, Cudaback E. Don't know what you got till it's gone: microglial depletion and neurodegeneration. Neural Regen Res 2021; 16:1921-1927. [PMID: 33642360 PMCID: PMC8343303 DOI: 10.4103/1673-5374.308078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In the central nervous system, immunologic surveillance and response are carried out, in large part, by microglia. These resident macrophages derive from myeloid precursors in the embryonic yolk sac, migrating to the brain and eventually populating local tissue prior to blood-brain barrier formation. Preserved for the duration of lifespan, microglia serve the host as more than just a central arm of innate immunity, also contributing significantly to the development and maintenance of neurons and neural networks, as well as neuroregeneration. The critical nature of these varied functions makes the characterization of key roles played by microglia in neurodegenerative disorders, especially Alzheimer's disease, of paramount importance. While genetic models and rudimentary pharmacologic approaches for microglial manipulation have greatly improved our understanding of central nervous system health and disease, significant advances in the selective and near complete in vitro and in vivo depletion of microglia for neuroscience application continue to push the boundaries of research. Here we discuss the research efficacy and utility of various microglial depletion strategies, including the highly effective CSF1R inhibitor models, noteworthy insights into the relationship between microglia and neurodegeneration, and the potential for therapeutic repurposing of microglial depletion and repopulation.
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Affiliation(s)
- David Graykowski
- Department of Health Sciences, DePaul University, Chicago, IL, USA
| | - Eiron Cudaback
- Department of Health Sciences, DePaul University, Chicago, IL, USA
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16
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Jia N, Chong J, Sun L. Application of stem cell biology in treating neurodegenerative diseases. Int J Neurosci 2020; 132:815-825. [PMID: 33081549 DOI: 10.1080/00207454.2020.1840376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
BACKGROUND The appropriate strategies are needed for stimulating the endogenous neurogenesis or introducing extrinsic neural progenitors, which could be harnessed as the regenerative resources for cueing the neurodegenerations. Adult neurogenesis is the endogenous continuing physiology in limited brain regions such as hippocampus, olfactory system, and hypothalamus. Besides adult neurogenesis, induced pluripotent stem cells (iPSCs) induced functional neurons could be another option for regenerative therapies. OBJECTIVE Current studies are trying to improve the adult neurogenesis and enable the iPSCs induced neurons into neural regeneration. Methods: Here in this review, we mainly introduced the recent progress in neural stem cell biology and its application in the treatment of the neurodegenerations. We main separated the strategy in summarizing the mediators and potential targets to promoting endogenous neural regeneration and transplantation of neural progenitors. CONCLUSION By collecting and comparing the advantages disadvantages between above-mentioned two strategies, we will offer the insight on future development of stem cell therapy in treating neurodegenerative patients.
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Affiliation(s)
- Na Jia
- Beijing University of Posts and Telecommunications, Beijing, China
| | - Jingping Chong
- Beijing University of Posts and Telecommunications, Beijing, China.,Shanghai University of Engineering Science, Shanghai, China
| | - Lina Sun
- Beijing University of Posts and Telecommunications, Beijing, China.,College of PE and Sport, Beijing Normal University, Beijing, China
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17
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Denny WA, Flanagan JU. Small-molecule CSF1R kinase inhibitors; review of patents 2015-present. Expert Opin Ther Pat 2020; 31:107-117. [PMID: 33108917 DOI: 10.1080/13543776.2021.1839414] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Colony stimulating factor 1 receptor (CSF-1R, also known as c-FMS kinase) is in the class III receptor tyrosine kinase family, along with c-Kit, Flt3 and PDGFRα. CSF-1/CSF-1R signaling promotes the differentiation and survival of myeloid progenitors into populations of monocytes, macrophages, dendritic cells and osteoclasts, as well as microglial cells and also recruits host macrophages to develop into tumor-associated macrophages (TAMs), which promote tumor progression and metastasis. AREAS COVERED In the last 5 years, and recently stimulated by the approval of pexidartinib (Turalio™, Daiichi Sankyo) in 2019 for the treatment of tenosynovial giant cell tumors, there has been a large increase in activity (both journal articles and patent applications) around small molecule inhibitors of CSF1R. Features of this work have been the surprising diversity of chemical classes shown to be potent and selective inhibitors, and the breadth of disease states (cancer, arthritis, and 'cytokine storm' syndromes) covered by CSF1R inhibitors. All these aspects are covered in the following sections. EXPERT OPINION The field has developed rapidly from 2014 to the present, with many different chemotypes proving to be potent inhibitors. The range of potential utilities of CSF1R inhibitors has also expanded to include dementia, ulcerative colitis/Crohn's disease, rheumatoid arthritis inflammation, and fibrosis.
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Affiliation(s)
- William A Denny
- Auckland Cancer Society Research Centre, School of Medical Sciences and Maurice Wilkins Centre, University of Auckland , Auckland, New Zealand
| | - Jack U Flanagan
- Auckland Cancer Society Research Centre, School of Medical Sciences and Maurice Wilkins Centre, University of Auckland , Auckland, New Zealand.,Department of Pharmacology and Clinical Pharmacology, School of Medical Sciences, University of Auckland , Auckland, New Zealand
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18
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Araki T, Ikegaya Y, Koyama R. The effects of microglia‐ and astrocyte‐derived factors on neurogenesis in health and disease. Eur J Neurosci 2020; 54:5880-5901. [PMID: 32920880 PMCID: PMC8451940 DOI: 10.1111/ejn.14969] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022]
Abstract
Hippocampal neurogenesis continues throughout life and has been suggested to play an essential role in maintaining spatial cognitive function under physiological conditions. An increasing amount of evidence has indicated that adult neurogenesis is tightly controlled by environmental conditions in the neurogenic niche, which consists of multiple types of cells including microglia and astrocytes. Microglia maintain the environment of neurogenic niche through their phagocytic capacity and interaction with neurons via fractalkine‐CX3CR1 signaling. In addition, microglia release growth factors such as brain‐derived neurotrophic factor (BDNF) and cytokines such as tumor necrosis factor (TNF)‐α to support the development of adult born neurons. Astrocytes also manipulate neurogenesis by releasing various soluble factors including adenosine triphosphate and lactate. Whereas, under pathological conditions such as Alzheimer's disease, depression, and epilepsy, microglia and astrocytes play a leading role in inflammation and are involved in attenuating the normal process of neurogenesis. The modulation of glial functions on neurogenesis in these brain diseases are attracting attention as a new therapeutic target. This review describes how these glial cells play a role in adult hippocampal neurogenesis in both health and disease, especially focusing glia‐derived factors.
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Affiliation(s)
- Tasuku Araki
- Laboratory of Chemical Pharmacology Graduate School of Pharmaceutical Sciences The University of Tokyo Tokyo Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology Graduate School of Pharmaceutical Sciences The University of Tokyo Tokyo Japan
- Center for Information and Neural Networks Suita City Osaka Japan
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology Graduate School of Pharmaceutical Sciences The University of Tokyo Tokyo Japan
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19
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Hanslik KL, Ulland TK. The Role of Microglia and the Nlrp3 Inflammasome in Alzheimer's Disease. Front Neurol 2020; 11:570711. [PMID: 33071950 PMCID: PMC7530640 DOI: 10.3389/fneur.2020.570711] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 08/13/2020] [Indexed: 12/13/2022] Open
Abstract
Alzheimer's disease (AD) is the most prevalent form of late-onset dementia. AD affects the health of millions of people in the United States and worldwide. Currently, there are no approved therapies that can halt or reverse the clinical progression of AD. Traditionally, AD is characterized first by the appearance of amyloid-β (Aβ) plaques followed by the formation of intraneuronal neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau (p-tau). These lesions are linked to synapse loss and eventual cognitive impairment. Additionally, microgliosis is consistently found in regions of the brain with AD pathology. The role of microglia in AD onset and progression remains unclear. Several recent reports indicate that the assembly of the multi-protein complex known as the NOD, LRR, and pyrin-domain containing 3 (Nlrp3) inflammasome by microglia results in apoptosis spec-like protein containing a CARD (Asc) spec formation, which then nucleates new Aβ plaques, thus amplifying Aβ-associated pathology. NFTs can also activate the Nlrp3 inflammasome leading to enhanced tau-associated pathology. Here, we will review the role of microglia and the activation of the inflammasome in the innate immune response to AD.
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Affiliation(s)
- Kendra L Hanslik
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States
| | - Tyler K Ulland
- Neuroscience Training Program, University of Wisconsin, Madison, WI, United States.,Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI, United States
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20
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Koller EJ, Chakrabarty P. Tau-Mediated Dysregulation of Neuroplasticity and Glial Plasticity. Front Mol Neurosci 2020; 13:151. [PMID: 32973446 PMCID: PMC7472665 DOI: 10.3389/fnmol.2020.00151] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/20/2020] [Indexed: 01/14/2023] Open
Abstract
The inability of individual neurons to compensate for aging-related damage leads to a gradual loss of functional plasticity in the brain accompanied by progressive impairment in learning and memory. Whereas this loss in neuroplasticity is gradual during normal aging, in neurodegenerative diseases such as Alzheimer’s disease (AD), this loss is accelerated dramatically, leading to the incapacitation of patients within a decade of onset of cognitive symptoms. The mechanisms that underlie this accelerated loss of neuroplasticity in AD are still not completely understood. While the progressively increasing proteinopathy burden, such as amyloid β (Aβ) plaques and tau tangles, definitely contribute directly to a neuron’s functional demise, the role of non-neuronal cells in controlling neuroplasticity is slowly being recognized as another major factor. These non-neuronal cells include astrocytes, microglia, and oligodendrocytes, which through regulating brain homeostasis, structural stability, and trophic support, play a key role in maintaining normal functioning and resilience of the neuronal network. It is believed that chronic signaling from these cells affects the homeostatic network of neuronal and non-neuronal cells to an extent to destabilize this harmonious milieu in neurodegenerative diseases like AD. Here, we will examine the experimental evidence regarding the direct and indirect pathways through which astrocytes and microglia can alter brain plasticity in AD, specifically as they relate to the development and progression of tauopathy. In this review article, we describe the concepts of neuroplasticity and glial plasticity in healthy aging, delineate possible mechanisms underlying tau-induced plasticity dysfunction, and discuss current clinical trials as well as future disease-modifying approaches.
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Affiliation(s)
- Emily J Koller
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States
| | - Paramita Chakrabarty
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States.,McKnight Brain Institute, University of Florida, Gainesville, FL, United States
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21
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Lucassen PJ, Fitzsimons CP, Salta E, Maletic-Savatic M. Adult neurogenesis, human after all (again): Classic, optimized, and future approaches. Behav Brain Res 2020; 381:112458. [DOI: 10.1016/j.bbr.2019.112458] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 11/29/2019] [Accepted: 12/28/2019] [Indexed: 02/08/2023]
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22
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Li S, Hayden EY, Garcia VJ, Fuchs DT, Sheyn J, Daley DA, Rentsendorj A, Torbati T, Black KL, Rutishauser U, Teplow DB, Koronyo Y, Koronyo-Hamaoui M. Activated Bone Marrow-Derived Macrophages Eradicate Alzheimer's-Related Aβ 42 Oligomers and Protect Synapses. Front Immunol 2020; 11:49. [PMID: 32082319 PMCID: PMC7005081 DOI: 10.3389/fimmu.2020.00049] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/09/2020] [Indexed: 12/13/2022] Open
Abstract
Impaired synaptic integrity and function due to accumulation of amyloid β-protein (Aβ42) oligomers is thought to be a major contributor to cognitive decline in Alzheimer's disease (AD). However, the exact role of Aβ42 oligomers in synaptotoxicity and the ability of peripheral innate immune cells to rescue synapses remain poorly understood due to the metastable nature of oligomers. Here, we utilized photo-induced cross-linking to stabilize pure oligomers and study their effects vs. fibrils on synapses and protection by Aβ-phagocytic macrophages. We found that cortical neurons were more susceptible to Aβ42 oligomers than fibrils, triggering additional neuritic arborization retraction, functional alterations (hyperactivity and spike waveform), and loss of VGluT1- and PSD95-excitatory synapses. Co-culturing neurons with bone marrow-derived macrophages protected synapses against Aβ42 fibrils; moreover, immune activation with glatiramer acetate (GA) conferred further protection against oligomers. Mechanisms involved increased Aβ42 removal by macrophages, amplified by GA stimulation: fibrils were largely cleared through intracellular CD36/EEA1+-early endosomal proteolysis, while oligomers were primarily removed via extracellular/MMP-9 enzymatic degradation. In vivo studies in GA-immunized or CD115+-monocyte-grafted APPSWE/PS1ΔE9-transgenic mice followed by pre- and postsynaptic analyses of entorhinal cortex and hippocampal substructures corroborated our in vitro findings of macrophage-mediated synaptic preservation. Together, our data demonstrate that activated macrophages effectively clear Aβ42 oligomers and rescue VGluT1/PSD95 synapses, providing rationale for harnessing macrophages to treat AD.
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Affiliation(s)
- Songlin Li
- Institute of Neuroscience and Chemistry, Wenzhou University, Wenzhou, China
- Institute of Life Sciences, Wenzhou University, Wenzhou, China
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - Eric Y. Hayden
- Department of Neurology, David Geffen School of Medicine at UCLA, Mary S. Easton Center for Alzheimer's Disease Research at UCLA, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Veronica J. Garcia
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Dieu-Trang Fuchs
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - Julia Sheyn
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - David A. Daley
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - Altan Rentsendorj
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - Tania Torbati
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, United States
| | - Keith L. Black
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - Ueli Rutishauser
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - David B. Teplow
- Department of Neurology, David Geffen School of Medicine at UCLA, Mary S. Easton Center for Alzheimer's Disease Research at UCLA, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Yosef Koronyo
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Cedars-Sinai Medical Center, Maxine-Dunitz Neurosurgical Institute, Los Angeles, CA, United States
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
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23
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Abstract
Microglia are increasingly shown to be key players in neuron development and synapse connectivity. However, the underlying mechanisms by which microglia regulate neuron function remain poorly understood in part because such analysis is challenging in the brain where neurons and synapses are intermingled and connectivity is only beginning to be mapped. Here, we discuss the features and function of microglia in the ordered mammalian retina where the laminar organization of neurons and synapses facilitates such molecular studies. We discuss microglia origins and consider the evidence for molecularly distinct microglia subpopulations and their potential for differential roles with a particular focus on the early stages of retina development. We then review the models and methods used for the study of these cells and discuss emerging data that link retina microglia to the genesis and survival of particular retina cell subtypes. We also highlight potential roles for microglia in shaping the development and organization of the vasculature and discuss cellular and molecular mechanisms involved in this process. Such insights may help resolve the mechanisms by which retinal microglia impact visual function and help guide studies of related features in brain development and disease.
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Affiliation(s)
- Fenge Li
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danye Jiang
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Melanie A Samuel
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, 77030, USA.
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