1
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Beiter RM, Sheehan PW, Schafer DP. Microglia phagocytic mechanisms: Development informing disease. Curr Opin Neurobiol 2024; 86:102877. [PMID: 38631077 PMCID: PMC11162951 DOI: 10.1016/j.conb.2024.102877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/21/2024] [Accepted: 03/25/2024] [Indexed: 04/19/2024]
Abstract
Microglia are tissue-resident macrophages and professional phagocytes of the central nervous system (CNS). In development, microglia-mediated phagocytosis is important for sculpting the cellular architecture. This includes the engulfment of dead/dying cells, pruning extranumerary synapses and axons, and phagocytosing fragments of myelin sheaths. Intriguingly, these developmental phagocytic mechanisms by which microglia sculpt the CNS are now appreciated as important for eliminating synapses, myelin, and proteins during neurodegeneration. Here, we discuss parallels between neurodevelopment and neurodegeneration, which highlights how development is informing disease. We further discuss recent advances and challenges towards therapeutically targeting these phagocytic pathways and how we can leverage development to overcome these challenges.
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Affiliation(s)
- Rebecca M Beiter
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Patrick W Sheehan
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Dorothy P Schafer
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA.
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2
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Barry-Carroll L, Gomez-Nicola D. The molecular determinants of microglial developmental dynamics. Nat Rev Neurosci 2024; 25:414-427. [PMID: 38658739 DOI: 10.1038/s41583-024-00813-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2024] [Indexed: 04/26/2024]
Abstract
Microglia constitute the largest population of parenchymal macrophages in the brain and are considered a unique subset of central nervous system glial cells owing to their extra-embryonic origins in the yolk sac. During development, microglial progenitors readily proliferate and eventually colonize the entire brain. In this Review, we highlight the origins of microglial progenitors and their entry routes into the brain and discuss the various molecular and non-molecular determinants of their fate, which may inform their specific functions. Specifically, we explore recently identified mechanisms that regulate microglial colonization of the brain, including the availability of space, and describe how the expansion of highly proliferative microglial progenitors facilitates the occupation of the microglial niche. Finally, we shed light on the factors involved in establishing microglial identity in the brain.
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Affiliation(s)
- Liam Barry-Carroll
- Nutrineuro, UMR 1286 INRAE, Bordeaux University, Bordeaux INP, Bordeaux, France
| | - Diego Gomez-Nicola
- School of Biological Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
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3
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Hussein MT, Sayed RKA, Mokhtar DM. Neuron mapping in the Molly fish optic tectum: An emphasis on the adult neurogenesis process. Microsc Res Tech 2024. [PMID: 38778562 DOI: 10.1002/jemt.24617] [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: 12/19/2023] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Teleost fish exhibit the most pronounced and widespread adult neurogenesis. Recently, functional development and the fate of newborn neurons have been reported in the optic tectum (OT) of fish. To determine the role of neurogenesis in the OT, this study used histological, immunohistochemical, and electron microscopic investigations on 18 adult Molly fish specimens (Poecilia sphenops). The OT of the Molly fish was a bilateral lobed structure located in the dorsal part of the mesencephalon. It exhibited a laminated structure made up of alternating fiber and cellular layers, which were organized into six main layers. The stratum opticum (SO) was supplied by optic nerve fibers, in which the neuropil was the main component. Radial bipolar neurons that possessed bundles of microtubules were observed in the stratum fibrosum et griseum superficiale (SFGS). Furthermore, oligodendrocytes with their processes wrapped around the nerve fibers could be observed. The stratum album centrale (SAC) consisted mainly of the axons of the stratum griseum centrale (SGC) and the large tectal, pyriform, and horizontal neurons. The neuronal cells of the SO and large tectal cells of the SAC expressed autophagy-related protein-5 (APG5). Interleukin-1β (IL-1β) was expressed in both neurons and glia cells of SGC. Additionally, inducible nitric oxide synthase (iNOS) was expressed in the neuropil of the SAC synaptic layer and granule cells of the stratum periventriculare (SPV). Also, transforming growth factor beta (TGF-β), SRY-box transcription factor 9 (SOX9), and myostatin were clearly expressed in the proliferative neurons. In all strata, S100 protein and Oligodendrocyte Lineage Transcription Factor 2 (Olig2) were expressed by microglia, oligodendrocytes, and astrocytes. In conclusion, it was possible to identify different varieties of neurons in the optic tectum, each with a distinct role. The existence of astrocytes, proliferative neurons, and stem cells highlights the regenerative capacity of OT. RESEARCH HIGHLIGHTS: The OT of the Molly fish exhibited a laminated structure made up of alternating fiber and cellular layers, which were organized into six main layers. Radial bipolar neurons that possessed bundles of microtubules were observed in the stratum fibrosum et griseum superficiale (SFGS). The stratum album central (SAC) consisted mainly of the axons of the stratum griseum centrale (SGC) and the large tectal, pyriform, and horizontal neurons. Inducible nitric oxide synthase (iNOS) was expressed in the neuropil of the SAC synaptic layer and granule cells of the stratum periventricular (SPV). Also, transforming growth factor beta (TGF-β), SRY-box transcription factor 9 (SOX9), and myostatin were clearly expressed in the proliferative neurons. The existence of astrocytes, proliferative neurons, and stem cells highlights the regenerative capacity of OT.
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Affiliation(s)
- Manal T Hussein
- Department of Cell and Tissues, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
| | - Ramy K A Sayed
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Sohag University, Sohag, Egypt
| | - Doaa M Mokhtar
- Department of Cell and Tissues, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
- Department of Histology and Anatomy, School of Veterinary Medicine, Badr University in Assiut, New Nasser City, Assiut, Egypt
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4
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Fritze J, Muralidharan C, Stamp E, Ahlenius H. Microglia undergo disease-associated transcriptional activation and CX3C motif chemokine receptor 1 expression regulates neurogenesis in the aged brain. Dev Neurobiol 2024. [PMID: 38616340 DOI: 10.1002/dneu.22939] [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: 07/31/2023] [Revised: 01/31/2024] [Accepted: 03/16/2024] [Indexed: 04/16/2024]
Abstract
Adult neurogenesis continues throughout life but declines dramatically with age and in neurodegenerative disorders such as Alzheimer's disease. In parallel, microglia become activated resulting in chronic inflammation in the aged brain. A unique type of microglia, suggested to support neurogenesis, exists in the subventricular zone (SVZ), but little is known how they are affected by aging. We analyzed the transcriptome of aging microglia and identified a unique neuroprotective activation profile in aged SVZ microglia, which is partly shared with disease-associated microglia (DAM). CX3C motif chemokine receptor 1 (CX3CR1) is characteristically expressed by brain microglia where it directs migration to targets for phagocytosis. We show that Cx3cr1 expression, as in DAM, is downregulated in old SVZ microglia and that heterozygous Cx3cr1 mice have increased proliferation and neuroblast number in the aged SVZ but not in the dentate gyrus, identifying CX3CR1 signaling as a novel age and brain region-specific regulator of neurogenesis.
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Affiliation(s)
- Jonas Fritze
- Department of Experimental Medical Sciences, Faculty of Medicine, Stem Cells, Aging and Neurodegeneration Group, Lund University, Lund, Sweden
- Lund Stem Cell Center, Lund, Sweden
| | - Chandramouli Muralidharan
- Department of Experimental Medical Sciences, Faculty of Medicine, Stem Cells, Aging and Neurodegeneration Group, Lund University, Lund, Sweden
- Lund Stem Cell Center, Lund, Sweden
- Department of Experimental Medical Science, Faculty of Medicine, Molecular Neurogenetics Group, Lund University, Lund, Sweden
| | - Eleanor Stamp
- Department of Experimental Medical Sciences, Faculty of Medicine, Stem Cells, Aging and Neurodegeneration Group, Lund University, Lund, Sweden
- Lund Stem Cell Center, Lund, Sweden
| | - Henrik Ahlenius
- Department of Experimental Medical Sciences, Faculty of Medicine, Stem Cells, Aging and Neurodegeneration Group, Lund University, Lund, Sweden
- Lund Stem Cell Center, Lund, Sweden
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5
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Milani SZ, Rezabakhsh A, Karimipour M, Salimi L, Mardi N, Narmi MT, Sadeghsoltani F, Valioglu F, Rahbarghazi R. Role of autophagy in angiogenic potential of vascular pericytes. Front Cell Dev Biol 2024; 12:1347857. [PMID: 38380339 PMCID: PMC10877016 DOI: 10.3389/fcell.2024.1347857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/24/2024] [Indexed: 02/22/2024] Open
Abstract
The vasculature system is composed of a multiplicity of juxtaposed cells to generate a functional biological barrier between the blood and tissues. On the luminal surface of blood vessels, endothelial cells (ECs) are in close contact with circulating cells while supporting basal lamina and pericytes wrap the abluminal surface. Thus, the reciprocal interaction of pericytes with ECs is a vital element in the physiological activity of the vascular system. Several reports have indicated that the occurrence of pericyte dysfunction under ischemic and degenerative conditions results in varied micro and macro-vascular complications. Emerging evidence points to the fact that autophagy, a conserved self-digestive cell machinery, can regulate the activity of several cells like pericytes in response to various stresses and pathological conditions. Here, we aim to highlight the role of autophagic response in pericyte activity and angiogenesis potential following different pathological conditions.
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Affiliation(s)
- Soheil Zamen Milani
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Aysa Rezabakhsh
- Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Karimipour
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Leila Salimi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Narges Mardi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | | | - Ferzane Valioglu
- Technology Development Zones Management CO., Sakarya University, Sakarya, Türkiye
| | - Reza Rahbarghazi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Applied Cellular Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
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6
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Morales M, Findley AP, Mitchell DM. Intercellular contact and cargo transfer between Müller glia and to microglia precede apoptotic cell clearance in the developing retina. Development 2024; 151:dev202407. [PMID: 38174987 PMCID: PMC10820749 DOI: 10.1242/dev.202407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024]
Abstract
To clarify our understanding of glial phagocytosis in retinal development, we used real-time imaging of larval zebrafish to provide cell-type specific resolution of this process. We show that radial Müller glia frequently participate in microglial phagocytosis while also completing a subset of phagocytic events. Müller glia actively engage with dying cells through initial target cell contact and phagocytic cup formation, after which an exchange of the dying cell from Müller glia to microglia often takes place. In addition, we find evidence that Müller glia cellular material, possibly from the initial Müller cell phagocytic cup, is internalized into microglial compartments. Previously undescribed Müller cell behaviors were seen, including cargo splitting, wrestling for targets and lateral passing of cargo to neighbors. Collectively, our work provides new insight into glial functions and intercellular interactions, which will allow future work to understand these behaviors on a molecular level.
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Affiliation(s)
- Michael Morales
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Anna P. Findley
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Diana M. Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
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7
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Morales M, Findley AP, Mitchell DM. Intercellular contact and cargo transfer between Müller glia and to microglia precede apoptotic cell clearance in the developing retina. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561302. [PMID: 37873206 PMCID: PMC10592698 DOI: 10.1101/2023.10.06.561302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
To clarify our understanding of glial phagocytosis in retinal development, we used real time imaging of larval zebrafish to provide cell-type specific resolution of this process. We show that radial Müller glia frequently participate in microglial phagocytosis while also completing a subset of phagocytic events. Müller glia (MG) actively engage with dying cells through initial target cell contact and phagocytic cup formation after which an exchange of the dying cell from MG to microglia often takes place. Additionally, we find evidence that Müller glia cellular material, possibly from the initial Müller cell's phagocytic cup, is internalized into microglial compartments. Previously undescribed Müller cell behaviors were seen, including cargo splitting, wrestling for targets, lateral passing of cargo to neighbors, and engulfment of what is possibly synaptic puncta. Collectively, our work provides new insight into glial functions and intercellular interactions, which will allow future work to understand these behaviors on a molecular level.
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Affiliation(s)
| | - Anna P Findley
- Biological Sciences, University of Idaho, Moscow, ID 83844
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8
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Emmerich K, White DT, Kambhampati SP, Casado GL, Fu TM, Chunawala Z, Sahoo A, Nimmagadda S, Krishnan N, Saxena MT, Walker SL, Betzig E, Kannan RM, Mumm JS. Nanoparticle-based targeting of microglia improves the neural regeneration enhancing effects of immunosuppression in the zebrafish retina. Commun Biol 2023; 6:534. [PMID: 37202450 PMCID: PMC10193316 DOI: 10.1038/s42003-023-04898-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/02/2023] [Indexed: 05/20/2023] Open
Abstract
Retinal Müller glia function as injury-induced stem-like cells in zebrafish but not mammals. However, insights gleaned from zebrafish have been applied to stimulate nascent regenerative responses in the mammalian retina. For instance, microglia/macrophages regulate Müller glia stem cell activity in the chick, zebrafish, and mouse. We previously showed that post-injury immunosuppression by the glucocorticoid dexamethasone accelerated retinal regeneration kinetics in zebrafish. Similarly, microglia ablation enhances regenerative outcomes in the mouse retina. Targeted immunomodulation of microglia reactivity may therefore enhance the regenerative potential of Müller glia for therapeutic purposes. Here, we investigated potential mechanisms by which post-injury dexamethasone accelerates retinal regeneration kinetics, and the effects of dendrimer-based targeting of dexamethasone to reactive microglia. Intravital time-lapse imaging revealed that post-injury dexamethasone inhibited microglia reactivity. The dendrimer-conjugated formulation: (1) decreased dexamethasone-associated systemic toxicity, (2) targeted dexamethasone to reactive microglia, and (3) improved the regeneration enhancing effects of immunosuppression by increasing stem/progenitor proliferation rates. Lastly, we show that the gene rnf2 is required for the enhanced regeneration effect of D-Dex. These data support the use of dendrimer-based targeting of reactive immune cells to reduce toxicity and enhance the regeneration promoting effects of immunosuppressants in the retina.
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Affiliation(s)
- Kevin Emmerich
- McKusick-Nathans Institute of the Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - David T White
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Siva P Kambhampati
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
- The Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Grace L Casado
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Tian-Ming Fu
- Janelia Farms Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Department of Electrical and Computer Engineering and Princeton Bioengineering Initiative, Princeton University, Princeton, NJ, USA
| | - Zeeshaan Chunawala
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Arpan Sahoo
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Saumya Nimmagadda
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Nimisha Krishnan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Meera T Saxena
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Steven L Walker
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Eric Betzig
- Janelia Farms Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
| | - Rangaramanujam M Kannan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
- The Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Jeff S Mumm
- McKusick-Nathans Institute of the Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
- The Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
- Solomon H Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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9
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Sun Y, Che J, Zhang J. Emerging non-proinflammatory roles of microglia in healthy and diseased brains. Brain Res Bull 2023; 199:110664. [PMID: 37192719 DOI: 10.1016/j.brainresbull.2023.110664] [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: 07/14/2022] [Revised: 04/04/2023] [Accepted: 05/13/2023] [Indexed: 05/18/2023]
Abstract
Microglia, the resident myeloid cells of the central nervous system, are the first line of defense against foreign pathogens, thereby confining the extent of brain injury. However, the role of microglia is not limited to macrophage-like functions. In addition to proinflammatory response mediation, microglia are involved in neurodevelopmental remodeling and homeostatic maintenance in the absence of disease. An increasing number of studies have also elucidated microglia-mediated regulation of tumor growth and neural repair in diseased brains. Here, we review the non-proinflammatory roles of microglia, with the aim of promoting a deeper understanding of the functions of microglia in healthy and diseased brains and contributing to the development of novel therapeutics that target microglia in neurological disorders.
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Affiliation(s)
- Yinying Sun
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, 200032, Shanghai China.
| | - Ji Che
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, 200032, Shanghai China.
| | - Jun Zhang
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, 200032, Shanghai China; Department of Oncology, Shanghai Medical College, Fudan University, 200032, Shanghai China.
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10
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Chen X, Wang Q, Yang J, Zhang L, Liu TT, Liu J, Deng BL, Liu J. Diagnostic and therapeutic value of P2Y12R in epilepsy. Front Pharmacol 2023; 14:1179028. [PMID: 37234715 PMCID: PMC10206044 DOI: 10.3389/fphar.2023.1179028] [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: 03/03/2023] [Accepted: 04/28/2023] [Indexed: 05/28/2023] Open
Abstract
There lacks biomarkers in current epilepsy diagnosis, and epilepsy is thus exposed to inadequate treatment, making it necessarily important to conduct search on new biomarkers and drug targets. The P2Y12 receptor is primarily expressed on microglia in the central nervous system, and acts as intrinsic immune cells in the central nervous system mediating neuroinflammation. In previous studies, P2Y12R in epilepsy has been found capable of controlling neuroinflammation and regulating neurogenesis as well as immature neuronal projections, and its expression is altered. P2Y12R is involved in microglia inhibition of neuronal activity and timely termination of seizures in acute seizures. In status epilepticus, the failure of P2Y12R in the process of "brake buffering" may not terminate the neuronal hyperexcitability timely. In chronic epilepsy, neuroinflammation causes seizures, which can in turn induce neuroinflammation, while on the other hand, neuroinflammation leads to neurogenesis, thereby causing abnormal neuronal discharges that give rise to seizures. In this case, targeting P2Y12R may be a novel strategy for the treatment of epilepsy. The detection of P2Y12R and its expression changes can contribute to the diagnosis of epilepsy. Meanwhile, the P2Y12R single-nucleotide polymorphism is associated with epilepsy susceptibility and endowed with the potential to individualize epilepsy diagnosis. To this end, functions of P2Y12R in the central nervous system were hereby reviewed, the effects of P2Y12R in epilepsy were explored, and the potential of P2Y12R in the diagnosis and treatment of epilepsy was further demonstrated.
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Affiliation(s)
- Xiang Chen
- Department of Neurology, School of Clinical Medicine, Southwest Medical University, Luzhou, China
| | - Qi Wang
- Department of Neurology, Sichuan Academy of Medical Sciences, Sichuan Provincial People’s Hospital, Chengdu, China
| | - Jie Yang
- Zunyi Medical University, Zunyi, China
| | - Li Zhang
- Electrophysiology Unit, Department of Neurology, Chengdu Fourth People’s Hospital, Chengdu, China
| | - Ting-Ting Liu
- Department of Neurology, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Jun Liu
- Department of Geriatric Neurology, Qinglongchang Ward, Chengdu Sixth People’s Hospital, Chengdu, China
| | - Bin-Lu Deng
- Department of Neurology, School of Clinical Medicine, Southwest Medical University, Luzhou, China
| | - Jie Liu
- Department of Neurology, School of Clinical Medicine, Southwest Medical University, Luzhou, China
- Department of Neurology, Sichuan Academy of Medical Sciences, Sichuan Provincial People’s Hospital, Chengdu, China
- Department of Neurology, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
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11
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Sun LWH, Asana Marican HT, Shen H. In Vivo Imaging of Radiation-Induced Apoptosis at Single-Cell Resolution in Transgenic Zebrafish Embryos. Radiat Res 2023; 199:229-239. [PMID: 36745564 DOI: 10.1667/rade-22-00174.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 01/17/2023] [Indexed: 02/07/2023]
Abstract
Among the various types of cell death induced by ionizing radiation, apoptosis is a highly regulated and well-characterized form. Investigating radiation-induced apoptosis in an intact organism offers advantages in capturing the dynamics of apoptosis under preserved physiology, although high resolution imaging remains challenging. Owing to their optical transparency and genetic amenability, zebrafish is an ideal animal model for research into this aspect. In this study, we present a secA5 transgenic zebrafish expressing genetically encoded secreted ANNEXIN V fused with mVenus, a yellow fluorescent protein that enables reporting of radiation-induced apoptosis. Using in vivo imaging approach, we show that after 2 Gy total-body irradiation, apoptosis could be visualized at single-cell resolution in different cell types throughout the embryo. Elevated apoptosis could be imaged and quantified in the neuroepithelium of the embryonic brain, as well as the proliferative zone and parenchyma of the larval brain. In addition, clearance of apoptotic cells by microglia, the professional phagocytes residing in the brain, could be imaged at single-cell resolution in irradiated larvae. These results establish transgenic secA5 zebrafish as a useful and versatile in vivo system for investigating the dynamic process of radiation-induced apoptosis.
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Affiliation(s)
| | | | - Hongyuan Shen
- Singapore Nuclear Research and Safety Initiative, National University of Singapore, Singapore
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12
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Hutto RA, Rutter KM, Giarmarco MM, Parker ED, Chambers ZS, Brockerhoff SE. Cone photoreceptors transfer damaged mitochondria to Müller glia. Cell Rep 2023; 42:112115. [PMID: 36795565 PMCID: PMC10425575 DOI: 10.1016/j.celrep.2023.112115] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 12/21/2022] [Accepted: 01/30/2023] [Indexed: 02/17/2023] Open
Abstract
Mitochondria are vital organelles that require sophisticated homeostatic mechanisms for maintenance. Intercellular transfer of damaged mitochondria is a recently identified strategy broadly used to improve cellular health and viability. Here, we investigate mitochondrial homeostasis in the vertebrate cone photoreceptor, the specialized neuron that initiates our daytime and color vision. We find a generalizable response to mitochondrial stress that leads to loss of cristae, displacement of damaged mitochondria from their normal cellular location, initiation of degradation, and transfer to Müller glia cells, a key non-neuronal support cell in the retina. Our findings show transmitophagy from cones to Müller glia as a response to mitochondrial damage. Intercellular transfer of damaged mitochondria represents an outsourcing mechanism that photoreceptors use to support their specialized function.
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Affiliation(s)
- Rachel A Hutto
- Biochemistry Department, The University of Washington, Seattle, WA 98195, USA
| | - Kaitlyn M Rutter
- Biochemistry Department, The University of Washington, Seattle, WA 98195, USA
| | | | - Edward D Parker
- Ophthalmology Department, The University of Washington, Seattle, WA 98109, USA
| | - Zachary S Chambers
- Biochemistry Department, The University of Washington, Seattle, WA 98195, USA
| | - Susan E Brockerhoff
- Biochemistry Department, The University of Washington, Seattle, WA 98195, USA; Ophthalmology Department, The University of Washington, Seattle, WA 98109, USA.
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13
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Lovel AG, Mitchell DM. PCNA Staining of Retinal Cryosections to Assess Microglial/Macrophage Proliferation. Methods Mol Biol 2023; 2636:389-400. [PMID: 36881312 DOI: 10.1007/978-1-0716-3012-9_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Detection of the protein PCNA (proliferating cell nuclear antigen) is used to identify cells in the S phase of the cell cycle to indicate cellular proliferation. Here we describe our method to detect PCNA expression by microglia and macrophages in retinal cryosections. We have used this procedure with zebrafish tissue, but this procedure could be applied to cryosections from any organism. Retinal cryosections are subjected to a heat-mediated antigen retrieval step in Citrate Buffer, then immunostained with antibodies to label PCNA and microglia/macrophages, and counterstained for cell nuclei. After fluorescent microscopy, the number of total and PCNA+ microglia/macrophages can be quantified and normalized to compare across samples and groups.
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Affiliation(s)
- Anna G Lovel
- Biological Sciences, University of Idaho, Moscow, ID, USA
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14
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North HF, Weissleder C, Fullerton JM, Webster MJ, Weickert CS. Increased immune cell and altered microglia and neurogenesis transcripts in an Australian schizophrenia subgroup with elevated inflammation. Schizophr Res 2022; 248:208-218. [PMID: 36108465 DOI: 10.1016/j.schres.2022.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 07/18/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022]
Abstract
We previously identified a subgroup of schizophrenia cases (~40 %) with heightened inflammation in the neurogenic subependymal zone (SEZ) (North et al., 2021b). This schizophrenia subgroup had changes indicating reduced microglial activity, increased peripheral immune cells, increased stem cell dormancy/quiescence and reduced neuronal precursor cells. The present follow-up study aimed to replicate and extend those novel findings in an independent post-mortem cohort of schizophrenia cases and controls from Australia. RNA was extracted from SEZ tissue from 20 controls and 22 schizophrenia cases from the New South Wales Brain Tissue Resource Centre, and gene expression analysis was performed. Cluster analysis of inflammation markers (IL1B, IL1R1, SERPINA3 and CXCL8) revealed a high-inflammation schizophrenia subgroup comprising 52 % of cases, which was a significantly greater proportion than the 17 % of high-inflammation controls. Consistent with our previous report (North et al., 2021b), those with high-inflammation and schizophrenia had unchanged mRNA expression of markers for steady-state and activated microglia (IBA1, HEXB, CD68), decreased expression of phagocytic microglia markers (P2RY12, P2RY13), but increased expression of markers for macrophages (CD163), monocytes (CD14), natural killer cells (FCGR3A), and the adhesion molecule ICAM1. Similarly, the high-inflammation schizophrenia subgroup emulated increased quiescent stem cell marker (GFAPD) and decreased neuronal progenitor (DLX6-AS1) and immature neuron marker (DCX) mRNA expression; but also revealed a novel increase in a marker of immature astrocytes (VIM). Replicating primary results in an independent cohort demonstrates that inflammatory subgroups in the SEZ in schizophrenia are reliable, robust and enhance understanding of neuropathological heterogeneity when studying schizophrenia.
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Affiliation(s)
- Hayley F North
- Neuroscience Research Australia, Sydney, NSW, Australia; School of Psychiatry, Faculty of Medicine & Health, University of New South Wales, Sydney, NSW, Australia
| | - Christin Weissleder
- Neuroscience Research Australia, Sydney, NSW, Australia; German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany; Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Janice M Fullerton
- Neuroscience Research Australia, Sydney, NSW, Australia; School of Medical Sciences, Faculty of Medicine & Health, University of New South Wales, Sydney, NSW, Australia
| | - Maree J Webster
- Laboratory of Brain Research, Stanley Medical Research Institute, 9800 Medical Center Drive, Rockville, MD, USA
| | - Cynthia Shannon Weickert
- Neuroscience Research Australia, Sydney, NSW, Australia; School of Psychiatry, Faculty of Medicine & Health, University of New South Wales, Sydney, NSW, Australia; Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, NY, USA.
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15
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Cserép C, Schwarcz AD, Pósfai B, László ZI, Kellermayer A, Környei Z, Kisfali M, Nyerges M, Lele Z, Katona I, Ádám Dénes. Microglial control of neuronal development via somatic purinergic junctions. Cell Rep 2022; 40:111369. [PMID: 36130488 PMCID: PMC9513806 DOI: 10.1016/j.celrep.2022.111369] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 06/28/2022] [Accepted: 08/25/2022] [Indexed: 11/30/2022] Open
Abstract
Microglia, the resident immune cells of the brain, play important roles during development. Although bi-directional communication between microglia and neuronal progenitors or immature neurons has been demonstrated, the main sites of interaction and the underlying mechanisms remain elusive. By using advanced methods, here we provide evidence that microglial processes form specialized contacts with the cell bodies of developing neurons throughout embryonic, early postnatal, and adult neurogenesis. These early developmental contacts are highly reminiscent of somatic purinergic junctions that are instrumental for microglia-neuron communication in the adult brain. The formation and maintenance of these junctions is regulated by functional microglial P2Y12 receptors, and deletion of P2Y12Rs disturbs proliferation of neuronal precursors and leads to aberrant cortical cytoarchitecture during development and in adulthood. We propose that early developmental formation of somatic purinergic junctions represents an important interface for microglia to monitor the status of immature neurons and control neurodevelopment.
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Affiliation(s)
- Csaba Cserép
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary.
| | - Anett D Schwarcz
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Balázs Pósfai
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary; Szentágothai János Doctoral School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Zsófia I László
- "Momentum" Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, 1083 Budapest, Hungary; University of Dundee, School of Medicine, Dundee DD1 9SY, UK
| | - Anna Kellermayer
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Zsuzsanna Környei
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Máté Kisfali
- "Momentum" Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Miklós Nyerges
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Zsolt Lele
- "Momentum" Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - István Katona
- "Momentum" Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, 1083 Budapest, Hungary; Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
| | - Ádám Dénes
- "Momentum" Laboratory of Neuroimmunology, Institute of Experimental Medicine, 1083 Budapest, Hungary.
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16
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Sebastian A, Hum NR, McCool JL, Wilson SP, Murugesh DK, Martin KA, Rios-Arce ND, Amiri B, Christiansen BA, Loots GG. Single-cell RNA-Seq reveals changes in immune landscape in post-traumatic osteoarthritis. Front Immunol 2022; 13:938075. [PMID: 35967299 PMCID: PMC9373730 DOI: 10.3389/fimmu.2022.938075] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/06/2022] [Indexed: 12/13/2022] Open
Abstract
Osteoarthritis (OA) is the most common joint disease, affecting over 300 million people world-wide. Accumulating evidence attests to the important roles of the immune system in OA pathogenesis. Understanding the role of various immune cells in joint degeneration or joint repair after injury is vital for improving therapeutic strategies for treating OA. Post-traumatic osteoarthritis (PTOA) develops in ~50% of individuals who have experienced an articular trauma like an anterior cruciate ligament (ACL) rupture. Here, using the high resolution of single-cell RNA sequencing, we delineated the temporal dynamics of immune cell accumulation in the mouse knee joint after ACL rupture. Our study identified multiple immune cell types in the joint including neutrophils, monocytes, macrophages, B cells, T cells, NK cells and dendritic cells. Monocytes and macrophage populations showed the most dramatic changes after injury. Further characterization of monocytes and macrophages reveled 9 major subtypes with unique transcriptomics signatures, including a tissue resident Lyve1hiFolr2hi macrophage population and Trem2hiFcrls+ recruited macrophages, both showing enrichment for phagocytic genes and growth factors such as Igf1, Pdgfa and Pdgfc. We also identified several genes induced or repressed after ACL injury in a cell type-specific manner. This study provides new insight into PTOA-associated changes in the immune microenvironment and highlights macrophage subtypes that may play a role in joint repair after injury.
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Affiliation(s)
- Aimy Sebastian
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
- *Correspondence: Aimy Sebastian, ; Gabriela G. Loots,
| | - Nicholas R. Hum
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Jillian L. McCool
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
- School of Natural Sciences, University of California Merced, Merced, CA, United States
| | - Stephen P. Wilson
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Deepa K. Murugesh
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Kelly A. Martin
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Naiomy Deliz Rios-Arce
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Beheshta Amiri
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Blaine A. Christiansen
- Department of Orthopaedic Surgery, University of California Davis Health, Sacramento, CA, United States
| | - Gabriela G. Loots
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
- School of Natural Sciences, University of California Merced, Merced, CA, United States
- *Correspondence: Aimy Sebastian, ; Gabriela G. Loots,
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17
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Thiel WA, Blume ZI, Mitchell DM. Compensatory engulfment and Müller glia reactivity in the absence of microglia. Glia 2022; 70:1402-1425. [PMID: 35451181 DOI: 10.1002/glia.24182] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/05/2022] [Accepted: 04/08/2022] [Indexed: 01/25/2023]
Abstract
Microglia are known for important phagocytic functions in the vertebrate retina. Reports also suggest that Müller glia have phagocytic capacity, though the relative levels and contexts in which this occurs remain to be thoroughly examined. Here, we investigate Müller glial engulfment of dying cells in the developing zebrafish retina in the presence and absence of microglia, using a genetic mutant in which microglia do not develop. We show that in normal conditions clearance of dying cells is dominated by microglia; however, Müller glia do have a limited clearance role. In retinas lacking intact microglial populations, we found a striking increase in the engulfment load assumed by the Müller glia, which displayed prominent cellular compartments containing apoptotic cells, several of which localized with the early phagosome/endosome marker Rab5. Consistent with increased engulfment, lysosomal staining was also increased in Müller glia in the absence of microglia. Increased engulfment load led to evidence of Müller glia reactivity including upregulation of gfap but did not trigger cell cycle re-entry by differentiated Müller glia. Our work provides important insight into the phagocytic capacity of Müller glia and the ability for compensatory functions and downstream effects. Therefore, effects of microglial deficiency or depletion on other glial cell types should be well-considered in experimental manipulations, in neurodegenerative disease, and in therapeutic approaches that target microglia. Our findings further justify future work to understand differential mechanisms and contexts of phagocytosis by glial cells in the central nervous system, and the significance of these mechanisms in health and disease.
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Affiliation(s)
- Whitney A Thiel
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA
| | - Zachary I Blume
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA
| | - Diana M Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA
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18
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Wieghofer P, Engelbert M, Chui TYP, Rosen RB, Sakamoto T, Sebag J. Hyalocyte origin, structure, and imaging. EXPERT REVIEW OF OPHTHALMOLOGY 2022; 17:233-248. [PMID: 36632192 PMCID: PMC9831111 DOI: 10.1080/17469899.2022.2100762] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Introduction Hyalocytes have been recognized as resident tissue macrophages of the vitreous body since the mid-19th century. Despite this, knowledge about their origin, turnover, and dynamics is limited. Areas covered Historically, initial studies on the origin of hyalocytes used light and electron microscopy. Modern investigations across species including rodents and humans will be described. Novel imaging is now available to study human hyalocytes in vivo. The shared ontogeny with retinal microglia and their eventual interdependence as well as differences will be discussed. Expert opinion Owing to a common origin as myeloid cells, hyalocytes and retinal microglia have similarities, but hyalocytes appear to be distinct as resident macrophages of the vitreous body.
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Affiliation(s)
- Peter Wieghofer
- Cellular Neuroanatomy, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstraße 2, 86159 Augsburg, Germany,Corresponding authors: Peter Wieghofer. , J Sebag.
| | - Michael Engelbert
- Vitreous Retina Macula Consultants of New York, New York, NY 10022, USA.,LuEsther T. Mertz Retinal Research Center, Manhattan Eye, Ear and Throat Hospital, New York, NY 10065, USA.,Department of Ophthalmology, New York University School of Medicine, New York, NY 10016, USA
| | - Toco YP Chui
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Richard B Rosen
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, New York; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Taiji Sakamoto
- Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - J Sebag
- Doheny Eye Institute, UCLA, Los Angeles, CA, USA.,Clinical Ophthalmology, Stein Eye Institute, Geffen School of Medicine, UCLA, Los Angeles, CA, USA.,VMR Institute for Vitreous Macula Retina, Huntington Beach, CA, USA.,Corresponding authors: Peter Wieghofer. , J Sebag.
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19
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Thiel W, Esposito EJ, Findley AP, Blume ZI, Mitchell DM. Modulation of retinoid-X-receptors differentially regulates expression of apolipoprotein genes apoc1 and apoeb by zebrafish microglia. Biol Open 2021; 11:273656. [PMID: 34878094 PMCID: PMC8822359 DOI: 10.1242/bio.058990] [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] [Received: 08/13/2021] [Accepted: 11/30/2021] [Indexed: 11/20/2022] Open
Abstract
Transcriptome analyses performed in both human and zebrafish indicate strong expression of Apoe and Apoc1 by microglia. Apoe expression by microglia is well appreciated, but Apoc1 expression has not been well-examined. PPAR/RXR and LXR/RXR receptors appear to regulate expression of the apolipoprotein gene cluster in macrophages, but a similar role in microglia in vivo has not been studied. Here, we characterized microglial expression of apoc1 in the zebrafish central nervous system (CNS) in situ and demonstrate that in the CNS, apoc1 expression is unique to microglia. We then examined the effects of PPAR/RXR and LXR/RXR modulation on microglial expression of apoc1 and apoeb during early CNS development using a pharmacological approach. Changes in apoc1 and apoeb transcripts in response to pharmacological modulation were quantified by RT-qPCR in whole heads, and in individual microglia using hybridization chain reaction (HCR) in situ hybridization. We found that expression of apoc1 and apoeb by microglia were differentially regulated by LXR/RXR and PPAR/RXR modulating compounds, respectively, during development. Our results also suggest RXR receptors could be involved in endogenous induction of apoc1 expression by microglia. Collectively, our work supports the use of zebrafish to better understand regulation and function of these apolipoproteins in the CNS. Summary: Here we investigate expression of two apolipoprotein genes by microglia in the zebrafish model during normal development, and in contexts of pharmacological manipulations that target candidate regulatory receptors.
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Affiliation(s)
- Whitney Thiel
- Biological Sciences, University of Idaho, Moscow, ID 83844, Russia
| | - Emma J Esposito
- Biological Sciences, University of Idaho, Moscow, ID 83844, Russia
| | - Anna P Findley
- Biological Sciences, University of Idaho, Moscow, ID 83844, Russia
| | - Zachary I Blume
- Biological Sciences, University of Idaho, Moscow, ID 83844, Russia
| | - Diana M Mitchell
- Biological Sciences, University of Idaho, Moscow, ID 83844, Russia
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20
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Zhang X, Wang X, Wang S, Peng W, Ullah R, Fu J, Zhou Y, Shen Y. Trilogy Development of Proopiomelanocortin Neurons From Embryonic to Adult Stages in the Mice Retina. Front Cell Dev Biol 2021; 9:718851. [PMID: 34676208 PMCID: PMC8523858 DOI: 10.3389/fcell.2021.718851] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Proopiomelanocortin-positive amacrine cells (POMC ACs) were first discovered in adult mouse retinas in 2010; however, the development of POMC-ACs has not been studied. We bred POMC-EGFP mice to label POMC-positive cells and investigated the development of POMC neurons from embryonic to adult stages. We found that POMC neuron development is mainly divided into three stages: the embryonic stage, the closed-eye stage, and the open-eye stage. Each stage has unique characteristics. In the embryonic stage, POMC neurons appeared in the retina at about E13. There was a cell number developmental peak at E15, followed by a steep decline at E16. POMC neurons showed a large soma and increased spine numbers at the closed-eye stage, and two dendritic sublaminas formed in the inner plexiform layer (IPL). The appearance and increased soma size and dendrite numbers did not occur continuously in space. We found that the soma number was asymmetric between the superior and inferior retinas according to the developmental topographic map. Density peaked in the superior retina, which existed persistently in the retinal ganglion cell layer (GCL), but disappeared from the inner nuclear layer (INL) at about P6. At the same time, the soma distribution in the INL was the most regular. At the open-eye stage, the development of POMC neurons was nearly stable only with only an increase in the IPL width, which increased the soma–dendrite distance.
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Affiliation(s)
- Xuhong Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Xiaoyu Wang
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, China.,Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Senjie Wang
- Department of Endocrinology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Peng
- Department of Endocrinology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Rahim Ullah
- Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Junfen Fu
- Department of Endocrinology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yudong Zhou
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, China.,Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Ye Shen
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
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21
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Synapse development is regulated by microglial THIK-1 K + channels. Proc Natl Acad Sci U S A 2021; 118:2106294118. [PMID: 34642249 PMCID: PMC8545484 DOI: 10.1073/pnas.2106294118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2021] [Indexed: 12/17/2022] Open
Abstract
Microglia are the brain’s resident immune cells, surveying the brain with motile processes, which can remove pathogens but also prune unnecessary junctions between the neurons (synapses). A potassium channel, THIK-1, in the microglial membrane allows efflux of potassium from these cells and thereby regulates their membrane voltage as well as their process motility and release of inflammatory mediators. Here, using THIK-1–blocking drugs and THIK-1–deficient mice, we demonstrate that THIK-1 controls removal of synaptic material by microglia, which reduces the number of functional synapses in the developing brain.
Microglia are the resident immune cells of the central nervous system. They constantly survey the brain parenchyma for redundant synapses, debris, or dying cells, which they remove through phagocytosis. Microglial ramification, motility, and cytokine release are regulated by tonically active THIK-1 K+ channels on the microglial plasma membrane. Here, we examined whether these channels also play a role in phagocytosis. Using pharmacological blockers and THIK-1 knockout (KO) mice, we found that a lack of THIK-1 activity approximately halved both microglial phagocytosis and marker levels for the lysosomes that degrade phagocytically removed material. These changes may reflect a decrease of intracellular [Ca2+]i activity, which was observed when THIK-1 activity was reduced, since buffering [Ca2+]i reduced phagocytosis. Less phagocytosis is expected to result in impaired pruning of synapses. In the hippocampus, mice lacking THIK-1 expression had an increased number of anatomically and electrophysiologically defined glutamatergic synapses during development. This resulted from an increased number of presynaptic terminals, caused by impaired removal by THIK-1 KO microglia. The dependence of synapse number on THIK-1 K+ channels, which control microglial surveillance and phagocytic ability, implies that changes in the THIK-1 expression level in disease states may contribute to altering neural circuit function.
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22
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Oliveira-Giacomelli Á, Petiz LL, Andrejew R, Turrini N, Silva JB, Sack U, Ulrich H. Role of P2X7 Receptors in Immune Responses During Neurodegeneration. Front Cell Neurosci 2021; 15:662935. [PMID: 34122013 PMCID: PMC8187565 DOI: 10.3389/fncel.2021.662935] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/26/2021] [Indexed: 01/16/2023] Open
Abstract
P2X7 receptors are ion-gated channels activated by ATP. Under pathological conditions, the extensive release of ATP induces sustained P2X7 receptor activation, culminating in induction of proinflammatory pathways with inflammasome assembly and cytokine release. These inflammatory conditions, whether occurring peripherally or in the central nervous system (CNS), increase blood-brain-barrier (BBB) permeability. Besides its well-known involvement in neurodegeneration and neuroinflammation, the P2X7 receptor may induce BBB disruption and chemotaxis of peripheral immune cells to the CNS, resulting in brain parenchyma infiltration. For instance, despite common effects on cytokine release, P2X7 receptor signaling is also associated with metalloproteinase secretion and activation, as well as migration and differentiation of T lymphocytes, monocytes and dendritic cells. Here we highlight that peripheral immune cells mediate the pathogenesis of Multiple Sclerosis and Parkinson's and Alzheimer's disease, mainly through T lymphocyte, neutrophil and monocyte infiltration. We propose that P2X7 receptor activation contributes to neurodegenerative disease progression beyond its known effects on the CNS. This review discusses how P2X7 receptor activation mediates responses of peripheral immune cells within the inflamed CNS, as occurring in the aforementioned diseases.
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Affiliation(s)
| | - Lyvia Lintzmaier Petiz
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Roberta Andrejew
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Natalia Turrini
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Jean Bezerra Silva
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Ulrich Sack
- Institute of Clinical Immunology, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
- Institute of Clinical Immunology, Medical Faculty, University of Leipzig, Leipzig, Germany
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23
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Dixon MA, Greferath U, Fletcher EL, Jobling AI. The Contribution of Microglia to the Development and Maturation of the Visual System. Front Cell Neurosci 2021; 15:659843. [PMID: 33967697 PMCID: PMC8102829 DOI: 10.3389/fncel.2021.659843] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/29/2021] [Indexed: 12/20/2022] Open
Abstract
Microglia, the resident immune cells of the central nervous system (CNS), were once considered quiescent cells that sat in readiness for reacting to disease and injury. Over the last decade, however, it has become clear that microglia play essential roles in maintaining the normal nervous system. The retina is an easily accessible part of the central nervous system and therefore much has been learned about the function of microglia from studies in the retina and visual system. Anatomically, microglia have processes that contact all synapses within the retina, as well as blood vessels in the major vascular plexuses. Microglia contribute to development of the visual system by contributing to neurogenesis, maturation of cone photoreceptors, as well as refining synaptic contacts. They can respond to neural signals and in turn release a range of cytokines and neurotrophic factors that have downstream consequences on neural function. Moreover, in light of their extensive contact with blood vessels, they are also essential for regulation of vascular development and integrity. This review article summarizes what we have learned about the role of microglia in maintaining the normal visual system and how this has helped in understanding their role in the central nervous system more broadly.
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Affiliation(s)
- Michael A Dixon
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Ursula Greferath
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Andrew I Jobling
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
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24
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Dhakal S, Rotem-Bamberger S, Sejd JR, Sebbagh M, Ronin N, Frey RA, Beitsch M, Batty M, Taler K, Blackerby JF, Inbal A, Stenkamp DL. Selective Requirements for Vascular Endothelial Cells and Circulating Factors in the Regulation of Retinal Neurogenesis. Front Cell Dev Biol 2021; 9:628737. [PMID: 33898420 PMCID: PMC8060465 DOI: 10.3389/fcell.2021.628737] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/17/2021] [Indexed: 01/01/2023] Open
Abstract
Development of the vertebrate eye requires signaling interactions between neural and non-neural tissues. Interactions between components of the vascular system and the developing neural retina have been difficult to decipher, however, due to the challenges of untangling these interactions from the roles of the vasculature in gas exchange. Here we use the embryonic zebrafish, which is not yet reliant upon hemoglobin-mediated oxygen transport, together with genetic strategies for (1) temporally-selective depletion of vascular endothelial cells, (2) elimination of blood flow through the circulation, and (3) elimination of cells of the erythroid lineage, including erythrocytes. The retinal phenotypes in these genetic systems were not identical, with endothelial cell-depleted retinas displaying laminar disorganization, cell death, reduced proliferation, and reduced cell differentiation. In contrast, the lack of blood flow resulted in a milder retinal phenotype showing reduced proliferation and reduced cell differentiation, indicating that an endothelial cell-derived factor(s) is/are required for laminar organization and cell survival. The lack of erythrocytes did not result in an obvious retinal phenotype, confirming that defects in retinal development that result from vascular manipulations are not due to poor gas exchange. These findings underscore the importance of the cardiovascular system supporting and controlling retinal development in ways other than supplying oxygen. In addition, these findings identify a key developmental window for these interactions and point to distinct functions for vascular endothelial cells vs. circulating factors.
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Affiliation(s)
- Susov Dhakal
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Shahar Rotem-Bamberger
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Josilyn R Sejd
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Meyrav Sebbagh
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Nathan Ronin
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Ruth A Frey
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Mya Beitsch
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Megan Batty
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States.,Department of Biology, Gonzaga University, Spokane, WA, United States
| | - Kineret Taler
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Jennifer F Blackerby
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States.,Department of Biology, Gonzaga University, Spokane, WA, United States
| | - Adi Inbal
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
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25
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Nagashima M, Hitchcock PF. Inflammation Regulates the Multi-Step Process of Retinal Regeneration in Zebrafish. Cells 2021; 10:cells10040783. [PMID: 33916186 PMCID: PMC8066466 DOI: 10.3390/cells10040783] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/25/2021] [Accepted: 03/27/2021] [Indexed: 12/20/2022] Open
Abstract
The ability to regenerate tissues varies between species and between tissues within a species. Mammals have a limited ability to regenerate tissues, whereas zebrafish possess the ability to regenerate almost all tissues and organs, including fin, heart, kidney, brain, and retina. In the zebrafish brain, injury and cell death activate complex signaling networks that stimulate radial glia to reprogram into neural stem-like cells that repair the injury. In the retina, a popular model for investigating neuronal regeneration, Müller glia, radial glia unique to the retina, reprogram into stem-like cells and undergo a single asymmetric division to generate multi-potent retinal progenitors. Müller glia-derived progenitors then divide rapidly, numerically matching the magnitude of the cell death, and differentiate into the ablated neurons. Emerging evidence reveals that inflammation plays an essential role in this multi-step process of retinal regeneration. This review summarizes the current knowledge of the inflammatory events during retinal regeneration and highlights the mechanisms whereby inflammatory molecules regulate the quiescence and division of Müller glia, the proliferation of Müller glia-derived progenitors and the survival of regenerated neurons.
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26
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Jones MC, Koh JM, Cheong KH. Synaptic Pruning in Schizophrenia: Does Minocycline Modulate Psychosocial Brain Development? Bioessays 2021; 42:e2000046. [PMID: 33448432 DOI: 10.1002/bies.202000046] [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: 03/05/2020] [Revised: 05/29/2020] [Indexed: 02/06/2023]
Abstract
Recent studies suggest that the tetracycline antibiotic minocycline, or its cousins, hold therapeutic potential for affective and psychotic disorders. This is proposed on the basis of a direct effect on microglia-mediated frontocortical synaptic pruning (FSP) during adolescence, perhaps in genetically susceptible individuals harboring risk alleles in the complement component cascade that is involved in this normal process of CNS circuit refinement. In reviewing this field, it is argued that minocycline is actually probing and modulating a deeply evolved and intricate system wherein psychosocial stimuli sculpt the circuitry of the "social brain" underlying adult behavior and personality. Furthermore, this system can generate psychiatric morbidity that is not dependent on genetic variation. This view has important ramifications for understanding "pathologies" of human social behavior and cognition as well as providing long-sought potential mechanistic links between social experience and susceptibility to mental and physical disease.
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Affiliation(s)
- Michael C Jones
- Science, Mathematics & Technology Cluster, Singapore University of Technology and Design (SUTD), 8 Somapah Road, S487372, Singapore
| | - Jin Ming Koh
- California Institute of Technology, Pasadena, CA, 91125, USA
| | - Kang Hao Cheong
- Science, Mathematics & Technology Cluster, Singapore University of Technology and Design (SUTD), 8 Somapah Road, S487372, Singapore.,SUTD-Massachusetts Institute of Technology International Design Centre, S487372, Singapore
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27
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Grenn FP, Kim JJ, Makarious MB, Iwaki H, Illarionova A, Brolin K, Kluss JH, Schumacher‐Schuh AF, Leonard H, Faghri F, Billingsley K, Krohn L, Hall A, Diez‐Fairen M, Periñán MT, Foo JN, Sandor C, Webber C, Fiske BK, Gibbs JR, Nalls MA, Singleton AB, Bandres‐Ciga S, Reed X, Blauwendraat C. The Parkinson's Disease Genome-Wide Association Study Locus Browser. Mov Disord 2020; 35:2056-2067. [PMID: 32864809 PMCID: PMC7754106 DOI: 10.1002/mds.28197] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/27/2020] [Accepted: 06/10/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Parkinson's disease (PD) is a neurodegenerative disease with an often complex component identifiable by genome-wide association studies. The most recent large-scale PD genome-wide association studies have identified more than 90 independent risk variants for PD risk and progression across more than 80 genomic regions. One major challenge in current genomics is the identification of the causal gene(s) and variant(s) at each genome-wide association study locus. The objective of the current study was to create a tool that would display data for relevant PD risk loci and provide guidance with the prioritization of causal genes and potential mechanisms at each locus. METHODS We included all significant genome-wide signals from multiple recent PD genome-wide association studies including themost recent PD risk genome-wide association study, age-at-onset genome-wide association study, progression genome-wide association study, and Asian population PD risk genome-wide association study. We gathered data for all genes 1 Mb up and downstream of each variant to allow users to assess which gene(s) are most associated with the variant of interest based on a set of self-ranked criteria. Multiple databases were queried for each gene to collect additional causal data. RESULTS We created a PD genome-wide association study browser tool (https://pdgenetics.shinyapps.io/GWASBrowser/) to assist the PD research community with the prioritization of genes for follow-up functional studies to identify potential therapeutic targets. CONCLUSIONS Our PD genome-wide association study browser tool provides users with a useful method of identifying potential causal genes at all known PD risk loci from large-scale PD genome-wide association studies. We plan to update this tool with new relevant data as sample sizes increase and new PD risk loci are discovered. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Francis P. Grenn
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Jonggeol J. Kim
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Mary B. Makarious
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Hirotaka Iwaki
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
- Data Tecnica InternationalGlen EchoMarylandUSA
| | | | - Kajsa Brolin
- Lund UniversityTranslational Neurogenetics Unit, Department of Experimental Medical ScienceLundSweden
| | - Jillian H. Kluss
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | | | - Hampton Leonard
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
- Data Tecnica InternationalGlen EchoMarylandUSA
| | - Faraz Faghri
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
- Data Tecnica InternationalGlen EchoMarylandUSA
| | - Kimberley Billingsley
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Lynne Krohn
- Department of Human GeneticsMcGill UniversityMontrealQuebecCanada
| | - Ashley Hall
- Department of Molecular and Clinical PharmacologyInstitute of Translational Medicine, University of LiverpoolLiverpoolUK
| | - Monica Diez‐Fairen
- Fundació Docència i Recerca Mútua Terrassa and Movement Disorders Unit, Department of NeurologyUniversity Hospital Mútua TerrassaBarcelonaSpain
| | - Maria Teresa Periñán
- Unidad de Trastornos del Movimiento, Servicio de Neurología y Neurofisiología Clínica, Instituto de Biomedicina de SevillaHospital Universitario Virgen del Rocío/CSIC/Universidad de SevillaSevilleSpain
| | - Jia Nee Foo
- Lee Kong Chian School of MedicineNanyang Technological University SingaporeSingaporeSingapore
- Human GeneticsGenome Institute of Singapore, A*STARSingaporeSingapore
| | - Cynthia Sandor
- UK Dementia Research Institute, Cardiff UniversityCardiffUK
| | - Caleb Webber
- UK Dementia Research Institute, Cardiff UniversityCardiffUK
| | - Brian K. Fiske
- The Michael J. Fox Foundation for Parkinson's Research, Grand Central StationNew YorkNYUSA
| | - J. Raphael Gibbs
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Mike A. Nalls
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
- Data Tecnica InternationalGlen EchoMarylandUSA
| | - Andrew B. Singleton
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Sara Bandres‐Ciga
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Xylena Reed
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
| | - Cornelis Blauwendraat
- Laboratory of NeurogeneticsNational Institute on Aging, National Institutes of HealthBethesdaMarylandUSA
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28
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Takalo M, Wittrahm R, Wefers B, Parhizkar S, Jokivarsi K, Kuulasmaa T, Mäkinen P, Martiskainen H, Wurst W, Xiang X, Marttinen M, Poutiainen P, Haapasalo A, Hiltunen M, Haass C. The Alzheimer's disease-associated protective Plcγ2-P522R variant promotes immune functions. Mol Neurodegener 2020; 15:52. [PMID: 32917267 PMCID: PMC7488484 DOI: 10.1186/s13024-020-00402-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 09/06/2020] [Indexed: 01/19/2023] Open
Abstract
Background Microglia-specific genetic variants are enriched in several neurodegenerative diseases, including Alzheimer’s disease (AD), implicating a central role for alterations of the innate immune system in the disease etiology. A rare coding variant in the PLCG2 gene (rs72824905, p.P522R) expressed in myeloid lineage cells was recently identified and shown to reduce the risk for AD. Methods To assess the role of the protective variant in the context of immune cell functions, we generated a Plcγ2-P522R knock-in (KI) mouse model using CRISPR/Cas9 gene editing. Results Functional analyses of macrophages derived from homozygous KI mice and wild type (WT) littermates revealed that the P522R variant potentiates the primary function of Plcγ2 as a Pip2-metabolizing enzyme. This was associated with improved survival and increased acute inflammatory response of the KI macrophages. Enhanced phagocytosis was observed in mouse BV2 microglia-like cells overexpressing human PLCγ2-P522R, but not in PLCγ2-WT expressing cells. Immunohistochemical analyses did not reveal changes in the number or morphology of microglia in the cortex of Plcγ2-P522R KI mice. However, the brain mRNA signature together with microglia-related PET imaging suggested enhanced microglial functions in Plcγ2-P522R KI mice. Conclusion The AD-associated protective Plcγ2-P522R variant promotes protective functions associated with TREM2 signaling. Our findings provide further support for the idea that pharmacological modulation of microglia via TREM2-PLCγ2 pathway-dependent stimulation may be a novel therapeutic option for the treatment of AD.
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Affiliation(s)
- Mari Takalo
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Rebekka Wittrahm
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Benedikt Wefers
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), München, Munich, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München, Munich, Germany
| | - Samira Parhizkar
- Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Kimmo Jokivarsi
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Teemu Kuulasmaa
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Petra Mäkinen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Henna Martiskainen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Wolfgang Wurst
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), München, Munich, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Xianyuan Xiang
- Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Mikael Marttinen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Pekka Poutiainen
- Center of Diagnostic Imaging, Department of Cyclotron and Radiopharmacy, Kuopio University Hospital, Kuopio, Finland
| | - Annakaisa Haapasalo
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Mikko Hiltunen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
| | - Christian Haass
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), München, Munich, Germany. .,Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany. .,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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29
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Pinto MV, Fernandes A. Microglial Phagocytosis-Rational but Challenging Therapeutic Target in Multiple Sclerosis. Int J Mol Sci 2020; 21:ijms21175960. [PMID: 32825077 PMCID: PMC7504120 DOI: 10.3390/ijms21175960] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 08/12/2020] [Accepted: 08/17/2020] [Indexed: 12/14/2022] Open
Abstract
Multiple sclerosis (MS) is the most common autoimmune and demyelinating disease of the central nervous system (CNS), characterized, in the majority of cases, by initial relapses that later evolve into progressive neurodegeneration, severely impacting patients’ motor and cognitive functions. Despite the availability of immunomodulatory therapies effective to reduce relapse rate and slow disease progression, they all failed to restore CNS myelin that is necessary for MS full recovery. Microglia are the primary inflammatory cells present in MS lesions, therefore strongly contributing to demyelination and lesion extension. Thus, many microglial-based therapeutic strategies have been focused on the suppression of microglial pro-inflammatory phenotype and neurodegenerative state to reduce disease severity. On the other hand, the contribution of myelin phagocytosis advocating the neuroprotective role of microglia in MS has been less explored. Indeed, despite the presence of functional oligodendrocyte precursor cells (OPCs), within lesioned areas, MS plaques fail to remyelinate as a result of the over-accumulation of myelin-toxic debris that must be cleared away by microglia. Dysregulation of this process has been associated with the impaired neuronal recovery and deficient remyelination. In line with this, here we provide a comprehensive review of microglial myelin phagocytosis and its involvement in MS development and repair. Alongside, we discuss the potential of phagocytic-mediated therapeutic approaches and encourage their modulation as a novel and rational approach to ameliorate MS-associated pathology.
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Affiliation(s)
- Maria V. Pinto
- Neuron-Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal;
| | - Adelaide Fernandes
- Neuron-Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal;
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal
- Correspondence: ; Tel.: +351-217946400
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30
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Var SR, Byrd-Jacobs CA. Role of Macrophages and Microglia in Zebrafish Regeneration. Int J Mol Sci 2020; 21:E4768. [PMID: 32635596 PMCID: PMC7369716 DOI: 10.3390/ijms21134768] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 12/11/2022] Open
Abstract
Currently, there is no treatment for recovery of human nerve function after damage to the central nervous system (CNS), and there are limited regenerative capabilities in the peripheral nervous system. Since fish are known for their regenerative abilities, understanding how these species modulate inflammatory processes following injury has potential translational importance for recovery from damage and disease. Many diseases and injuries involve the activation of innate immune cells to clear damaged cells. The resident immune cells of the CNS are microglia, the primary cells that respond to infection and injury, and their peripheral counterparts, macrophages. These cells serve as key modulators of development and plasticity and have been shown to be important in the repair and regeneration of structure and function after injury. Zebrafish are an emerging model for studying macrophages in regeneration after injury and microglia in neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease. These fish possess a high degree of neuroanatomical, neurochemical, and emotional/social behavioral resemblance with humans, serving as an ideal simulator for many pathologies. This review explores literature on macrophage and microglial involvement in facilitating regeneration. Understanding innate immune cell behavior following damage may help to develop novel methods for treating toxic and chronic inflammatory processes that are seen in trauma and disease.
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31
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IL-4 and IL-10 promotes phagocytic activity of microglia by up-regulation of TREM2. Cytotechnology 2020; 72:589-602. [PMID: 32623621 DOI: 10.1007/s10616-020-00409-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 06/26/2020] [Indexed: 02/06/2023] Open
Abstract
Triggering receptor expressed on myeloid cells-2 (TREM2) is an innate immune receptor that promotes phagocytosis by microglia. However, whether TREM2 is related to the stimulus-dependent phagocytic activity of microglia is unclear. In this study, the primary cultured microglia were stimulated with interferon (IFN)-γ, interleukin (IL)-4, and interleukin (IL)-10, respectively, and their phagocytic activity against microbeads and apoptotic neural stem cells (NSCs) was measured. TREM2 of microglia was detected by qPCR and western blotting. The TREM2 signal was blocked in microglia using the siRNA technique. The results showed that IL-4 or IL-10 treatment significantly increased the number of microglia gathered around the apoptotic neurosphere. IL-4 and IL-10 treatment also promoted phagocytosis of microbeads and apoptotic NSCs by primary cultured microglia. The TREM2 expression was up-regulated in IL-4- or IL-10- treated microglia. TREM2 siRNA treatment blocked the phagocytic activity of IL-4- or IL-10-treated microglia. In conclusion, these results indicated that IL-4 and IL-10 promote the phagocytic activity of microglia by the up-regulation of TREM2, which suggested a new potential therapeutic target for neurodegenerative disease.
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