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Liu Y, Xie J, Yu Z, Gong M, Li Q, Yang G, Xu B, Xu T. Electroacupuncture at ST25 mediated glial cells pruning of pancreatic TRPV1 neural synapse responds to neuropathy-associated beta cell dysfunction. Chin Med 2025; 20:65. [PMID: 40380290 DOI: 10.1186/s13020-025-01099-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2024] [Accepted: 03/23/2025] [Indexed: 05/19/2025] Open
Abstract
Electroacupuncture (EA) is verified to modulate glycemic changes in T2DM, and this is partially related to sensory neurotransmitters. However, EA-mediated communication mechanism between them and acupoint specificity have not been fully clarified. Thus, we replicated the diabetic rat model induced by a high-fat diet/streptozotocin (HFD-STZ), and investigated the alleviating effects on insulin resistance (IR) and inflammation severity after EA at ST25. We also compared the effect difference of EA at ST37. Furthermore, we studied the changes of pancreatic sensory neurotransmitters and β cells (and their surrounding components) in detail. Serum glucose, insulin, IR, TNF-α and IL-10 were significantly elevated in model rats, and β cell function was impaired, which reversed by EA at ST25 or ST37 to varying degrees. EA at ST25 can enhance the expression of calcitonin gene-related peptide (CGRP), attenuate transient receptor potential vanilloid 1(TRPV1) and correct the secretion mismatch between them, while EA at ST37 has no such effect. Subsequently, EA at ST25-mediated TRPV1-CGRP-β cell circuit demonstrates an advantage in regulating glucose metabolism via direct insulin inhibition by CGRP. EA at ST25 rather than ST37 regulates the activity of peri-ilset glial cells and macrophages, playing a neuro-protective role and controlling inflammation. EA at ST37 exhibits its partial therapeutic effect on T2DM as it improves serum GLP-1. It also implies that the dominant target organ of ST37 may not be the pancreas, but other associated viscera. Hence, our study elucidates the EA-mediated glial cell via TRPV1-CGRP pathway regulation of β cell dysfunction after nerve lesion, and the hypoglycemic effect of ST25 is significantly better than that of ST37.
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Affiliation(s)
- Yun Liu
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jiahui Xie
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China
| | - Zhi Yu
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China
| | - Meirong Gong
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China
| | - Qian Li
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China
| | - Guanhu Yang
- Research Department, Swiss University of Traditional Chinese Medicine, Bad Zurzach, Switzerland
- Department of Specialty Medicine, Ohio University, Athens, 43055, USA
| | - Bin Xu
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China.
| | - Tiancheng Xu
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, China.
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2
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Ghena N, Anderson SR, Roberts JM, Irvin E, Schwakopf J, Bosco A, Vetter ML. CD11c-Expressing Microglia Are Transient, Driven by Interactions With Apoptotic Cells. Glia 2025; 73:1077-1089. [PMID: 39828972 PMCID: PMC11920677 DOI: 10.1002/glia.24674] [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: 07/16/2024] [Revised: 12/24/2024] [Accepted: 01/05/2025] [Indexed: 01/22/2025]
Abstract
Microglia, the parenchymal macrophage of the central nervous system, serve crucial remodeling functions throughout development. Microglia are transcriptionally heterogenous, suggesting that distinct microglial states confer discrete roles. Currently, little is known about how dynamic these states are, the cues that promote them, or how they impact microglial function. In the developing retina, we previously found a significant proportion of microglia express CD11c (Integrin αX, Itgax, subunit of complement receptor 4) which has also been reported in other developmental and disease contexts. Here, we sought to understand the regulation and function of CD11c+ microglia. We found that CD11c+ microglia track with prominent waves of neuronal apoptosis in postnatal retina. Using genetic fate mapping, we provide evidence that microglia transition out of the CD11c state to return to homeostasis. We show that CD11c+ microglia have elevated lysosomal content and contribute to the clearance of apoptotic neurons, and found that acquisition of CD11c expression is partially dependent upon the TAM receptor AXL. Using selective ablation, we found CD11c+ microglia are not uniquely critical for phagocytic clearance of apoptotic cells. Together, our data suggest that CD11c+ microglia are a transient state induced by developmental apoptosis rather than a specialized subset mediating phagocytic elimination.
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Affiliation(s)
- Nathaniel Ghena
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
- Interdepartmental Program in NeuroscienceUniversity of UtahSalt Lake CityUtahUSA
| | - Sarah R. Anderson
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
| | - Jacqueline M. Roberts
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
| | - Emmalyn Irvin
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
| | - Joon Schwakopf
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
| | - Alejandra Bosco
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
| | - Monica L. Vetter
- Department of NeurobiologyUniversity of Utah School of MedicineSalt Lake CityUtahUSA
- Interdepartmental Program in NeuroscienceUniversity of UtahSalt Lake CityUtahUSA
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3
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Wang F, Liu H, Ke Y, Huang X, Chen S, Zhuang D, Zhou Y, Wu M, Wang Y, Lai M, Liu H, Zhou W. Ibudilast-Mediated Suppression of Neuronal TLR4 in the Prefrontal Cortex Mitigates Methamphetamine-Induced Neuroinflammation and Addictive Behaviours. Addict Biol 2025; 30:e70033. [PMID: 40237256 PMCID: PMC12001051 DOI: 10.1111/adb.70033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2025] [Revised: 02/26/2025] [Accepted: 04/03/2025] [Indexed: 04/18/2025]
Abstract
Methamphetamine (METH) use leads to addiction, neurotoxicity, and neuroinflammation. Ibudilast, a toll-like receptor 4 (TLR4) inhibitor, has been shown to reduce METH-induced neuroinflammation and self-administration, but its specific role in neuronal TLR4 signalling and associated behavioural outcomes remains poorly understood. This study examined Ibudilast's effects on METH reward, drug-seeking behaviour, and TLR4 signalling in a rat self-administration model. Ibudilast was found to dose-dependently reduce METH intake and motivation for the drug, as evidenced by a downward shift in the dose-response curve and a decrease in breakpoint. Additionally, Ibudilast suppressed both cue- and METH priming-induced drug-seeking behaviours. Western blot analysis revealed elevated TLR4, p-NF-κB and IL-6 in the prefrontal cortex after 14 days of METH self-administration. These increases were significantly attenuated by Ibudilast treatment. Furthermore, local administration of Ibudilast in the prefrontal cortex led to a reduction in METH intake and motivation, as well as decreased TLR4 expression in this brain region. Immunofluorescence staining was revealed that TLR4 was expressed predominantly in neurons and microglia, with METH-induced upregulation of neuronal TLR4 being linked to apoptosis. Ibudilast restored normal spatial interactions between neurons and microglia, thereby mitigating neuroinflammation and neuronal damage. Furthermore, local injection of Ibudilast in the prefrontal cortex led to a reduction in METH intake and motivation, as well as decreased expression of TLR4 in the brain region. These findings underscore the critical role of neuronal TLR4 in METH addiction and highlight Ibudilast's therapeutic potential in addressing METH-related neuroinflammation and behavioural dysregulation.
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Affiliation(s)
- Fangmin Wang
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
- Department of PsychiatryThe Affiliated Kangning Hospital of Ningbo UniversityPeople's Republic of China
| | - Huizhen Liu
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
| | - Yuting Ke
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Xiaolei Huang
- Department of ObstetricsThe Affiliated Lihuili Hospital of Ningbo UniversityNingboP. R. China
| | - Shanshan Chen
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
- Department of PsychiatryThe Affiliated Kangning Hospital of Ningbo UniversityPeople's Republic of China
| | - Dingding Zhuang
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
- Department of PsychiatryThe Affiliated Kangning Hospital of Ningbo UniversityPeople's Republic of China
| | - Yiying Zhou
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
| | - Manqing Wu
- Shanghai Mental Health CenterShanghaiPeople's Republic of China
| | - Yuting Wang
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
| | - Miaojun Lai
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
- Department of PsychiatryThe Affiliated Kangning Hospital of Ningbo UniversityPeople's Republic of China
| | - Huifen Liu
- Zhejiang Provincial Key Lab of Addiction ResearchThe Affiliated Kangning Hospital of Ningbo UniversityNingboPeople's Republic of China
- Department of PsychiatryThe Affiliated Kangning Hospital of Ningbo UniversityPeople's Republic of China
| | - Wenhua Zhou
- Department of PsychiatryThe Affiliated Kangning Hospital of Ningbo UniversityPeople's Republic of China
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4
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Ren J, Zhou Y, Hu Y, Yang J, Fang H, Lyu X, Guo J, Shi X, Li Q. A model-based factorization method for scRNA data unveils bifurcating transcriptional modules underlying cell fate determination. eLife 2025; 13:RP97424. [PMID: 39907554 PMCID: PMC11798574 DOI: 10.7554/elife.97424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2025] Open
Abstract
Manifold-learning is particularly useful to resolve the complex cellular state space from single-cell RNA sequences. While current manifold-learning methods provide insights into cell fate by inferring graph-based trajectory at cell level, challenges remain to retrieve interpretable biology underlying the diverse cellular states. Here, we described MGPfactXMBD, a model-based manifold-learning framework and capable to factorize complex development trajectories into independent bifurcation processes of gene sets, and thus enables trajectory inference based on relevant features. MGPfactXMBD offers a more nuanced understanding of the biological processes underlying cellular trajectories with potential determinants. When bench-tested across 239 datasets, MGPfactXMBD showed advantages in major quantity-control metrics, such as branch division accuracy and trajectory topology, outperforming most established methods. In real datasets, MGPfactXMBD recovered the critical pathways and cell types in microglia development with experimentally valid regulons and markers. Furthermore, MGPfactXMBD discovered evolutionary trajectories of tumor-associated CD8+ T cells and yielded new subtypes of CD8+ T cells with gene expression signatures significantly predictive of the responses to immune checkpoint inhibitor in independent cohorts. In summary, MGPfactXMBD offers a manifold-learning framework in scRNA-seq data which enables feature selection for specific biological processes and contributing to advance our understanding of biological determination of cell fate.
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Affiliation(s)
- Jun Ren
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen UniversityXiamenChina
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen UniversityXiamenChina
- School of Informatics, Xiamen University, XiamenXiamenChina
| | - Ying Zhou
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen UniversityXiamenChina
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen UniversityXiamenChina
| | - Yudi Hu
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen UniversityXiamenChina
| | - Jing Yang
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen UniversityXiamenChina
| | - Hongkun Fang
- Department of Scientific Research Management, Weifang People’s Hospital, Shandong Second Medical UniversityWeifangChina
| | - Xuejing Lyu
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen UniversityXiamenChina
| | - Jintao Guo
- Department of Scientific Research Management, Weifang People’s Hospital, Shandong Second Medical UniversityWeifangChina
| | - Xiaodong Shi
- School of Informatics, Xiamen University, XiamenXiamenChina
| | - Qiyuan Li
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen UniversityXiamenChina
- Department of Hematology, The First Affiliated Hospital of Xiamen University and Institute of Hematology, School of Medicine, Xiamen UniversityXiamenChina
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5
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Cai L, Fan Q, Pang R, Chen C, Zhang Y, Xie H, Huang J, Wang Y, Li P, Huang D, Jin X, Zhou Y, Li Y. Microglia programmed cell death in neurodegenerative diseases and CNS injury. Apoptosis 2025; 30:446-465. [PMID: 39656359 PMCID: PMC11799081 DOI: 10.1007/s10495-024-02041-5] [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] [Accepted: 11/03/2024] [Indexed: 02/06/2025]
Abstract
Programmed cell death (PCD) has emerged as a critical regulatory mechanism in the initiation and progression of various pathological conditions. PCD in microglia, including necroptosis, pyroptosis, apoptosis, ferroptosis, and autophagy, occurs in a variety of central nervous system (CNS) diseases. Dysregulation of microglia can lead to excessive tissue damage or neuronal death in CNS injury. Various injury stimuli trigger aberrant activation of the PCD pathway of microglia, which then further leads to inflammatory cascades that exacerbates CNS pathology in a vicious cycle. Therefore, targeting PCD in microglia is considered an important avenue for the treatment of various neurodegenerative diseases and CNS injury. In this review, we summarize the major and recent findings focusing on the mechanisms of PCD in microglia modulating functions in neurodegenerative diseases and CNS injury and provide a systematic overview of the current inhibitors targeting various PCD pathways, which may provide important therapeutic targets that merit further investigation.
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Affiliation(s)
- Ling Cai
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiuyue Fan
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Rui Pang
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Chen
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yueman Zhang
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Haiyi Xie
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jingyi Huang
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Wang
- Clinical Research Center, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peiying Li
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Clinical Research Center, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dan Huang
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xia Jin
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Yuxi Zhou
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Yan Li
- Department of Anesthesiology, Key Laboratory of the Ministry of Education, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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6
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Huang KC, Tawfik M, Samuel MA. Retinal ganglion cell circuits and glial interactions in humans and mice. Trends Neurosci 2024; 47:994-1013. [PMID: 39455342 PMCID: PMC11631666 DOI: 10.1016/j.tins.2024.09.010] [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: 05/17/2024] [Revised: 08/30/2024] [Accepted: 09/26/2024] [Indexed: 10/28/2024]
Abstract
Retinal ganglion cells (RGCs) are the brain's gateway for vision, and their degeneration underlies several blinding diseases. RGCs interact with other neuronal cell types, microglia, and astrocytes in the retina and in the brain. Much knowledge has been gained about RGCs and glia from mice and other model organisms, often with the assumption that certain aspects of their biology may be conserved in humans. However, RGCs vary considerably between species, which could affect how they interact with their neuronal and glial partners. This review details which RGC and glial features are conserved between mice, humans, and primates, and which differ. We also discuss experimental approaches for studying human and primate RGCs. These strategies will help to bridge the gap between rodent and human RGC studies and increase study translatability to guide future therapeutic strategies.
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Affiliation(s)
- Kang-Chieh Huang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030. USA.
| | - Mohamed Tawfik
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030. USA
| | - Melanie A Samuel
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030. USA.
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7
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Wang Q, Zeng F, Fang C, Sun Y, Zhao X, Rong X, Zhang H, Xu Y. Galectin-3 alleviates demyelination by modulating microglial anti-inflammatory polarization through PPARγ-CD36 axis. Brain Res 2024; 1842:149106. [PMID: 38986827 DOI: 10.1016/j.brainres.2024.149106] [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: 05/08/2024] [Revised: 06/27/2024] [Accepted: 06/29/2024] [Indexed: 07/12/2024]
Abstract
Demyelination is characterized by disruption of myelin sheath and disorders in myelin formation. Currently, there are no effective therapeutic treatments available. Microglia, especially anti-inflammatory phenotype microglia are critical for remyelination. Galectin-3 (Gal-3), which is known to modulate microglia activation, is correlated with myelination. In this study, we aimed to elucidate the roles of Gal-3 during myelin formation and explore the efficiency and mechanism of rGal-3 administration in remyelination. We enrolled Gal-3 knockout (Lgals3 KO) mice and demonstrated Lgals3 KO causes demyelination during spontaneous myelinogenesis. We performed a cuprizone (CPZ) intoxication model and found Lgals3 KO aggravates demyelinated lesions and favors microglial pro-inflammatory phenotype polarization. Recombinant Gal-3 (rGal-3) administration alleviates CPZ intoxication and drives microglial towards anti-inflammatory phenotype. Additionally, RNA sequencing results reveal the correlation between Gal-3 and the PPARγ-CD36 axis. Thus, we performed SSO and GW9662 administration to inhibit the activation of the PPARγ-CD36 axis and found that rGal-3 administration modulates microglial phenotype polarization by regulating the PPARγ-CD36 axis. Together, our findings highlight the importance of Gal-3 in myelination and provide insights into rGal-3 administration for modulating microglial anti-inflammatory phenotype polarization through the PPARγ-CD36 axis.
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Affiliation(s)
- Qian Wang
- Department of Infectious and Liver Diseases, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China; Department of Neonatology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China.
| | - Fansen Zeng
- Department of Infectious and Liver Diseases, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China
| | - Chunxiao Fang
- Department of Infectious and Liver Diseases, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China
| | - Yi Sun
- Department of Neonatology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China
| | - Xiaopeng Zhao
- Department of Neonatology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China
| | - Xiao Rong
- Department of Neonatology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China
| | - Huayan Zhang
- Department of Neonatology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China.
| | - Yi Xu
- Department of Infectious and Liver Diseases, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, PR China.
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8
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Ghena N, Anderson SR, Roberts JM, Irvin E, Schwakopf J, Bosco A, Vetter ML. CD11c-expressing microglia are transient, driven by interactions with apoptotic cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.24.600082. [PMID: 38979153 PMCID: PMC11230207 DOI: 10.1101/2024.06.24.600082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Microglia, the parenchymal macrophage of the central nervous system serve crucial remodeling functions throughout development. Microglia are transcriptionally heterogenous, suggesting that distinct microglial states confer discrete roles. Currently, little is known about how dynamic these states are, the cues that promote them, or how they impact microglial function. In the developing retina, we previously found a significant proportion of microglia express CD11c (Integrin αX, complement receptor 4, Itgax) which has also been reported in other developmental and disease contexts. Here, we sought to understand the regulation and function of CD11c+ microglia. We found that CD11c+ microglia track with prominent waves of neuronal apoptosis in postnatal retina. Using genetic fate mapping, we provide evidence that microglia transition out of the CD11c state to return to homeostasis. We show that CD11c+ microglia have elevated lysosomal content and contribute to the clearance of apoptotic neurons, and found that acquisition of CD11c expression is, in part, dependent upon the TAM receptor Axl. Using selective ablation, we found CD11c+ microglia are not uniquely critical for phagocytic clearance of apoptotic cells. Together, our data suggest CD11c+ microglia are a transient state induced by developmental apoptosis rather than a specialized subset mediating phagocytic elimination.
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Affiliation(s)
- Nathaniel Ghena
- Department of Neurobiology, University of Utah School of Medicine
- Interdepartmental Program in Neuroscience, University of Utah
| | - Sarah R Anderson
- Department of Neurobiology, University of Utah School of Medicine
| | | | - Emmalyn Irvin
- Department of Neurobiology, University of Utah School of Medicine
| | - Joon Schwakopf
- Department of Neurobiology, University of Utah School of Medicine
| | - Alejandra Bosco
- Department of Neurobiology, University of Utah School of Medicine
| | - Monica L Vetter
- Department of Neurobiology, University of Utah School of Medicine
- Interdepartmental Program in Neuroscience, University of Utah
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9
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Huo A, Wang J, Li Q, Li M, Qi Y, Yin Q, Luo W, Shi J, Cong Q. Molecular mechanisms underlying microglial sensing and phagocytosis in synaptic pruning. Neural Regen Res 2024; 19:1284-1290. [PMID: 37905877 PMCID: PMC11467947 DOI: 10.4103/1673-5374.385854] [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: 04/15/2023] [Revised: 06/08/2023] [Accepted: 08/03/2023] [Indexed: 11/02/2023] Open
Abstract
Microglia are the main non-neuronal cells in the central nervous system that have important roles in brain development and functional connectivity of neural circuits. In brain physiology, highly dynamic microglial processes are facilitated to sense the surrounding environment and stimuli. Once the brain switches its functional states, microglia are recruited to specific sites to exert their immune functions, including the release of cytokines and phagocytosis of cellular debris. The crosstalk of microglia between neurons, neural stem cells, endothelial cells, oligodendrocytes, and astrocytes contributes to their functions in synapse pruning, neurogenesis, vascularization, myelination, and blood-brain barrier permeability. In this review, we highlight the neuron-derived "find-me," "eat-me," and "don't eat-me" molecular signals that drive microglia in response to changes in neuronal activity for synapse refinement during brain development. This review reveals the molecular mechanism of neuron-microglia interaction in synaptic pruning and presents novel ideas for the synaptic pruning of microglia in disease, thereby providing important clues for discovery of target drugs and development of nervous system disease treatment methods targeting synaptic dysfunction.
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Affiliation(s)
- Anran Huo
- Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University; Institute of Neuroscience and Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu Province, China
| | - Jiali Wang
- Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University; Institute of Neuroscience and Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu Province, China
| | - Qi Li
- Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University; Institute of Neuroscience and Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu Province, China
| | - Mengqi Li
- Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University; Institute of Neuroscience and Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu Province, China
| | - Yuwan Qi
- Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University; Institute of Neuroscience and Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu Province, China
| | - Qiao Yin
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Weifeng Luo
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Jijun Shi
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Qifei Cong
- Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University; Institute of Neuroscience and Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu Province, China
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10
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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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11
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Quinlan S, Khan T, McFall D, Campos-Rodriguez C, Forcelli PA. Early life phenobarbital exposure dysregulates the hippocampal transcriptome. Front Pharmacol 2024; 15:1340691. [PMID: 38606173 PMCID: PMC11007044 DOI: 10.3389/fphar.2024.1340691] [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: 12/05/2023] [Accepted: 03/01/2024] [Indexed: 04/13/2024] Open
Abstract
Introduction: Phenobarbital (PB) and levetiracetam (LEV) are the first-line therapies for neonates with diagnosed seizures, however, a growing body of evidence shows that these drugs given during critical developmental windows trigger lasting molecular changes in the brain. While the targets and mechanism of action of these drugs are well understood-what is not known is how these drugs alter the transcriptomic landscape, and therefore molecular profile/gene expression during these critical windows of neurodevelopment. PB is associated with a range of neurotoxic effects in developing animals, from cell death to altered synaptic development to lasting behavioral impairment. LEV does not produce these effects. Methods: Here we evaluated the effects of PB and Lev on the hippocampal transcriptome by RNA sequencing. Neonatal rat pups were given a single dose of PB, Lev or vehicle and sacrificed 72 h later-at time at which drug is expected to be cleared. Results: We found PB induces broad changes in the transcriptomic profile (124 differentially expressed transcripts), as compared to relatively small changes in LEV-treated animals (15 transcripts). PB exposure decreased GABAergic and oligodendrocyte markers pvalb and opalin, and increased the marker of activated microglia, cd68 and the astrocyte- associated gene vegfa. These data are consistent with the existing literature showing developmental neurotoxicity associated with PB, but not LEV. Discussion: The widespread change in gene expression after PB, which affected transcripts reflective of multiple cell types, may provide a link between acute drug administration and lasting drug toxicity.
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Affiliation(s)
- Seán Quinlan
- Department of Physiology and Pharmacology, Georgetown University, Washington, DC, United States
| | - Tahiyana Khan
- Department of Physiology and Pharmacology, Georgetown University, Washington, DC, United States
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States
| | - David McFall
- Department of Physiology and Pharmacology, Georgetown University, Washington, DC, United States
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States
| | | | - Patrick A. Forcelli
- Department of Physiology and Pharmacology, Georgetown University, Washington, DC, United States
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States
- Department of Neuroscience, Georgetown University, Washington, DC, United States
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12
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Weyer MP, Strehle J, Schäfer MKE, Tegeder I. Repurposing of pexidartinib for microglia depletion and renewal. Pharmacol Ther 2024; 253:108565. [PMID: 38052308 DOI: 10.1016/j.pharmthera.2023.108565] [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: 09/28/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/07/2023]
Abstract
Pexidartinib (PLX3397) is a small molecule receptor tyrosine kinase inhibitor of colony stimulating factor 1 receptor (CSF1R) with moderate selectivity over other members of the platelet derived growth factor receptor family. It is approved for treatment of tenosynovial giant cell tumors (TGCT). CSF1R is highly expressed by microglia, which are macrophages of the central nervous system (CNS) that defend the CNS against injury and pathogens and contribute to synapse development and plasticity. Challenged by pathogens, apoptotic cells, debris, or inflammatory molecules they adopt a responsive state to propagate the inflammation and eventually return to a homeostatic state. The phenotypic switch may fail, and disease-associated microglia contribute to the pathophysiology in neurodegenerative or neuropsychiatric diseases or long-lasting detrimental brain inflammation after brain, spinal cord or nerve injury or ischemia/hemorrhage. Microglia also contribute to the growth permissive tumor microenvironment of glioblastoma (GBM). In rodents, continuous treatment for 1-2 weeks via pexidartinib food pellets leads to a depletion of microglia and subsequent repopulation from the remaining fraction, which is aided by peripheral monocytes that search empty niches for engraftment. The putative therapeutic benefit of such microglia depletion or forced renewal has been assessed in almost any rodent model of CNS disease or injury or GBM with heterogeneous outcomes, but a tendency of partial beneficial effects. So far, microglia monitoring e.g. via positron emission imaging is not standard of care for patients receiving Pexidartinib (e.g. for TGCT), so that the depletion and repopulation efficiency in humans is still largely unknown. Considering the virtuous functions of microglia, continuous depletion is likely no therapeutic option but short-lasting transient partial depletion to stimulate microglia renewal or replace microglia in genetic disease in combination with e.g. stem cell transplantation or as part of a multimodal concept in treatment of glioblastoma appears feasible. The present review provides an overview of the preclinical evidence pro and contra microglia depletion as a therapeutic approach.
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Affiliation(s)
- Marc-Philipp Weyer
- Institute of Clinical Pharmacology, Goethe-University Frankfurt, Faculty of Medicine, Frankfurt, Germany
| | - Jenny Strehle
- Department of Anesthesiology, University Medical Center Johannes Gutenberg-University Mainz, Germany
| | - Michael K E Schäfer
- Department of Anesthesiology, University Medical Center Johannes Gutenberg-University Mainz, Germany
| | - Irmgard Tegeder
- Institute of Clinical Pharmacology, Goethe-University Frankfurt, Faculty of Medicine, Frankfurt, Germany.
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13
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Marín-Teva JL, Sepúlveda MR, Neubrand VE, Cuadros MA. Microglial Phagocytosis During Embryonic and Postnatal Development. ADVANCES IN NEUROBIOLOGY 2024; 37:151-161. [PMID: 39207691 DOI: 10.1007/978-3-031-55529-9_9] [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
Microglia play decisive roles during the development of the central nervous system (CNS). Phagocytosis is one of the classical functions attributed to microglia, being involved in nearly all phases of the embryonic and postnatal development of the brain, such as rapid clearance of cell debris to avoid an inflammatory response, controlling the number of neuronal and glial cells or their precursors, contribution to axon guidance and to refinement of synaptic connections. To carry out all these tasks, microglial cells are equipped with a panoply of receptors, that convert microglia to the "professional phagocytes" of the nervous parenchyma. These receptors are modulated by spatiotemporal cues that adapt the properties of microglia to the needs of the developing CNS. Thus, in this chapter, we will discuss the role of microglial phagocytosis in all the aforementioned processes. First, we will explain the general phagocytic process, to describe afterward the performance of microglial cells in detail.
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Affiliation(s)
- José L Marín-Teva
- Department of Cell Biology, Faculty of Sciences, University of Granada, Granada, Spain.
| | - M Rosario Sepúlveda
- Department of Cell Biology, Faculty of Sciences, University of Granada, Granada, Spain
| | - Veronika E Neubrand
- Department of Cell Biology, Faculty of Sciences, University of Granada, Granada, Spain
| | - Miguel A Cuadros
- Department of Cell Biology, Faculty of Sciences, University of Granada, Granada, Spain
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14
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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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15
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Tang J, Jin Y, Jia F, Lv T, Manaenko A, Zhang LF, Zhang Z, Qi X, Xue Y, Zhao B, Zhang X, Zhang JH, Lu J, Hu Q. Gas6 Promotes Microglia Efferocytosis and Suppresses Inflammation Through Activating Axl/Rac1 Signaling in Subarachnoid Hemorrhage Mice. Transl Stroke Res 2023; 14:955-969. [PMID: 36324028 DOI: 10.1007/s12975-022-01099-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/05/2022]
Abstract
Early brain injury (EBI) following subarachnoid hemorrhage (SAH) is characterized by rapid development of neuron apoptosis and dysregulated inflammatory response. Microglia efferocytosis plays a critical role in the clearance of apoptotic cells, attenuation of inflammation, and minimizing brain injury in various pathological conditions. Here, using a mouse SAH model, we aim to investigate whether microglia efferocytosis is involved in post-SAH inflammation and to determine the underlying signaling pathway. We hypothesized that TAM receptors and their ligands regulate this process. To prove our hypothesis, the expression and cellular location of TAM (Tyro3, Axl, and Mertk) receptors and their ligands growth arrest-specific 6 (Gas6) and Protein S (ProS1) were examined by PCR, western blots, and fluorescence immunostaining. Thirty minutes after SAH, mice received an intraventricular injection of recombinant Gas6 (rGas6) or recombinant ProS1 (rPros1) and underwent evaluations of inflammatory mediator expression, neurological deficits, and blood-brain barrier integrity at 24 h. Microglia efferocytosis of apoptotic neurons was analyzed in vivo and in vitro. The potential mechanism was determined by inhibiting or knocking down TAM receptors and Rac1 by specific inhibitors or siRNA. SAH induced upregulation of Axl and its ligand Gas6. The administration of rGas6 but not rPros1 promoted microglia efferocytosis, alleviated inflammation, and ameliorated SAH-induced BBB breakdown and neurological deficits. The beneficial effects of rGas6 were arrogated by inhibiting or knocking down Axl and Rac1. We concluded that rGas6 attenuated the development of early brain injury in mice after SAH by facilitating microglia efferocytosis and preventing inflammatory response, which is partly dependent on activation of Axl and Rac1.
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Affiliation(s)
- Junjia Tang
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201620, China
| | - Yichao Jin
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Feng Jia
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Tao Lv
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Anatol Manaenko
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Lin-Feng Zhang
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Zeyu Zhang
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Xin Qi
- Discipline of Neuroscience, Department of Physiology and Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yajun Xue
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201620, China
| | - Bin Zhao
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Xiaohua Zhang
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - John H Zhang
- Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, USA
| | - Jianfei Lu
- Discipline of Neuroscience, Department of Physiology and Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Songjiang Institute and Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201600, China.
| | - Qin Hu
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China.
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16
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Vecchiarelli HA, Tremblay MÈ. Microglial Transcriptional Signatures in the Central Nervous System: Toward A Future of Unraveling Their Function in Health and Disease. Annu Rev Genet 2023; 57:65-86. [PMID: 37384734 DOI: 10.1146/annurev-genet-022223-093643] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
Microglia, the resident immune cells of the central nervous system (CNS), are primarily derived from the embryonic yolk sac and make their way to the CNS during early development. They play key physiological and immunological roles across the life span, throughout health, injury, and disease. Recent transcriptomic studies have identified gene transcript signatures expressed by microglia that may provide the foundation for unprecedented insights into their functions. Microglial gene expression signatures can help distinguish them from macrophage cell types to a reasonable degree of certainty, depending on the context. Microglial expression patterns further suggest a heterogeneous population comprised of many states that vary according to the spatiotemporal context. Microglial diversity is most pronounced during development, when extensive CNS remodeling takes place, and following disease or injury. A next step of importance for the field will be to identify the functional roles performed by these various microglial states, with the perspective of targeting them therapeutically.
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Affiliation(s)
- Haley A Vecchiarelli
- Division of Medical Sciences, University of Victoria, British Columbia, Canada; ,
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, British Columbia, Canada; ,
- Centre for Advanced Materials and Related Technology and Institute on Aging and Lifelong Health, University of Victoria, British Columbia, Canada
- Département de Médecine Moléculaire and Axe Neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Quebec, Canada
- Department of Neurology and Neurosurgery, Faculty of Medicine and Health Sciences, McGill University, Quebec, Canada
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of British Columbia, British Columbia, Canada
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17
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Stanley ER, Biundo F, Gökhan Ş, Chitu V. Differential regulation of microglial states by colony stimulating factors. Front Cell Neurosci 2023; 17:1275935. [PMID: 37964794 PMCID: PMC10642290 DOI: 10.3389/fncel.2023.1275935] [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: 08/10/2023] [Accepted: 10/09/2023] [Indexed: 11/16/2023] Open
Abstract
Recent studies have emphasized the role of microglia in the progression of many neurodegenerative diseases. The colony stimulating factors, CSF-1 (M-CSF), granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF) regulate microglia through different cognate receptors. While the receptors for GM-CSF (GM-CSFR) and G-CSF (G-CSFR) are specific for their ligands, CSF-1 shares its receptor, the CSF-1 receptor-tyrosine kinase (CSF-1R), with interleukin-34 (IL-34). All four cytokines are expressed locally in the CNS. Activation of the CSF-1R in macrophages is anti-inflammatory. In contrast, the actions of GM-CSF and G-CSF elicit different activated states. We here review the roles of each of these cytokines in the CNS and how they contribute to the development of disease in a mouse model of CSF-1R-related leukodystrophy. Understanding their roles in this model may illuminate their contribution to the development or exacerbation of other neurodegenerative diseases.
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Affiliation(s)
- E. Richard Stanley
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Fabrizio Biundo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Şölen Gökhan
- Department of Neurology, Albert Einstein College of Medicine, Institute for Brain Disorders and Neural Regeneration, Bronx, NY, United States
| | - Violeta Chitu
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, United States
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18
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Wurl JA, Mac Nair CE, Dietz JA, Shestopalov VI, Nickells RW. Contralateral Astrocyte Response to Acute Optic Nerve Damage Is Mitigated by PANX1 Channel Activity. Int J Mol Sci 2023; 24:15641. [PMID: 37958624 PMCID: PMC10647301 DOI: 10.3390/ijms242115641] [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: 09/05/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Glial reactivity is considered a hallmark of damage-induced innate immune responses in the central nervous system. In the visual system, unilateral optic nerve damage elicits dramatic glial reactivity in the retina directly affected by the lesion and a similar, albeit more modest, effect in the contralateral eye. Evaluation of astrocyte changes in a mouse model of optic nerve crush indicates that astrocyte reactivity, as a function of retinal coverage and cellular hypertrophy, occurs within both the experimental and contralateral retinas, although the hypertrophic response of the astrocytes in the contralateral eyes is delayed for at least 24 h. Evaluation of astrocytic reactivity as a function of Gfap expression indicates a similar, muted but significant, response in contralateral eyes. This constrained glial response is completely negated by conditional knock out of Panx1 in both astrocytes and Müller cells. Further studies are required to identify if this is an autocrine or a paracrine suppression of astroglial reactivity.
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Affiliation(s)
- Jasmine A. Wurl
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
| | - Caitlin E. Mac Nair
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
| | - Joel A. Dietz
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
| | - Valery I. Shestopalov
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA;
| | - Robert W. Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
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19
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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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20
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Abstract
Because the central nervous system is largely nonrenewing, neurons and their synapses must be maintained over the lifetime of an individual to ensure circuit function. Age is a dominant risk factor for neural diseases, and declines in nervous system function are a common feature of aging even in the absence of disease. These alterations extend to the visual system and, in particular, to the retina. The retina is a site of clinically relevant age-related alterations but has also proven to be a uniquely approachable system for discovering principles that govern neural aging because it is well mapped, contains diverse neuron types, and is experimentally accessible. In this article, we review the structural and molecular impacts of aging on neurons within the inner and outer retina circuits. We further discuss the contribution of non-neuronal cell types and systems to retinal aging outcomes. Understanding how and why the retina ages is critical to efforts aimed at preventing age-related neural decline and restoring neural function.
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Affiliation(s)
- Jeffrey D Zhu
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, USA;
| | - Sharma Pooja Tarachand
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, USA;
| | - Qudrat Abdulwahab
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, USA;
| | - Melanie A Samuel
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, USA;
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21
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Traxler L, Lucciola R, Herdy JR, Jones JR, Mertens J, Gage FH. Neural cell state shifts and fate loss in ageing and age-related diseases. Nat Rev Neurol 2023; 19:434-443. [PMID: 37268723 PMCID: PMC10478103 DOI: 10.1038/s41582-023-00815-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2023] [Indexed: 06/04/2023]
Abstract
Most age-related neurodegenerative diseases remain incurable owing to an incomplete understanding of the disease mechanisms. Several environmental and genetic factors contribute to disease onset, with human biological ageing being the primary risk factor. In response to acute cellular damage and external stimuli, somatic cells undergo state shifts characterized by temporal changes in their structure and function that increase their resilience, repair cellular damage, and lead to their mobilization to counteract the pathology. This basic cell biological principle also applies to human brain cells, including mature neurons that upregulate developmental features such as cell cycle markers or glycolytic reprogramming in response to stress. Although such temporary state shifts are required to sustain the function and resilience of the young human brain, excessive state shifts in the aged brain might result in terminal fate loss of neurons and glia, characterized by a permanent change in cell identity. Here, we offer a new perspective on the roles of cell states in sustaining health and counteracting disease, and we examine how cellular ageing might set the stage for pathological fate loss and neurodegeneration. A better understanding of neuronal state and fate shifts might provide the means for a controlled manipulation of cell fate to promote brain resilience and repair.
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Affiliation(s)
- Larissa Traxler
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Raffaella Lucciola
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Joseph R Herdy
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Jeffrey R Jones
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Jerome Mertens
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA.
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA.
| | - Fred H Gage
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA.
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22
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Xu Y, Moulding D, Jin W, Beggs S. Microglial phagocytosis mediates long-term restructuring of spinal GABAergic circuits following early life injury. Brain Behav Immun 2023; 111:127-137. [PMID: 37037363 PMCID: PMC11932970 DOI: 10.1016/j.bbi.2023.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/21/2023] [Accepted: 04/05/2023] [Indexed: 04/12/2023] Open
Abstract
Peripheral injury during the early postnatal period alters the somatosensory system, leading to behavioural hyperalgesia upon re-injury in adulthood. Spinal microglia have been implicated as the cellular mediators of this phenomenon, but the mechanism is unclear. We hypothesised that neonatal injury (1) alters microglial phagocytosis of synapses in the dorsal horn leading to long-term structural changes in neurons, and/or (2) trains microglia, leading to a stronger microglial response after re-injury in adulthood. Using hindpaw surgical incision as a model we showed that microglial density and phagocytosis increased in the dorsal horn region innervated by the hindpaw. Dorsal horn microglia increased engulfment of synapses following injury, with a preference for those expressing the vesicular GABA transporter VGAT and primary afferent A-fibre terminals in neonates. This led to a long-term reduction of VGAT density in the dorsal horn and reduced microglial phagocytosis of VGLUT2 terminals. We also saw an increase in apoptosis following neonatal injury, which was not limited to the dorsal horn suggesting that larger circuit wide changes are happening. In adults, hindpaw incision increased microglial engulfment of predominantly VGAT synapses but did not alter the engulfment of A-fibres. This engulfment was not affected by prior neonatal injury, suggesting that microglial phagocytosis was not trained. These results highlight microglial phagocytosis in the dorsal horn as an important physiological response towards peripheral injury with potential long-term consequences and reveals differences in microglial responses between neonates and adults.
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Affiliation(s)
- Yajing Xu
- University College London, United Kingdom
| | - Dale Moulding
- University College London, United Kingdom; UCL GOS Institute of Child Health, United Kingdom
| | | | - Simon Beggs
- University College London, United Kingdom; UCL GOS Institute of Child Health, United Kingdom.
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23
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Birkle TJY, Brown GC. Syk inhibitors protect against microglia-mediated neuronal loss in culture. Front Aging Neurosci 2023; 15:1120952. [PMID: 37009452 PMCID: PMC10050448 DOI: 10.3389/fnagi.2023.1120952] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 02/28/2023] [Indexed: 03/17/2023] Open
Abstract
Microglia are brain macrophages and play beneficial and/or detrimental roles in many brain pathologies because of their inflammatory and phagocytic activity. Microglial inflammation and phagocytosis are thought to be regulated by spleen tyrosine kinase (Syk), which is activated by multiple microglial receptors, including TREM2 (Triggering Receptor Expressed on Myeloid Cells 2), implicated in neurodegeneration. Here, we have tested whether Syk inhibitors can prevent microglia-dependent neurodegeneration induced by lipopolysaccharide (LPS) in primary neuron-glia cultures. We found that the Syk inhibitors BAY61-3606 and P505-15 (at 1 and 10 μM, respectively) completely prevented the neuronal loss induced by LPS, which was microglia-dependent. Syk inhibition also prevented the spontaneous loss of neurons from older neuron-glia cultures. In the absence of LPS, Syk inhibition depleted microglia from the cultures and induced some microglial death. However, in the presence of LPS, Syk inhibition had relatively little effect on microglial density (reduced by 0-30%) and opposing effects on the release of two pro-inflammatory cytokines (IL-6 decreased by about 45%, TNFα increased by 80%). Syk inhibition also had no effect on the morphological transition of microglia exposed to LPS. On the other hand, inhibition of Syk reduced microglial phagocytosis of beads, synapses and neurons. Thus, Syk inhibition in this model is most likely neuroprotective by reducing microglial phagocytosis, however, the reduced microglial density and IL-6 release may also contribute. This work adds to increasing evidence that Syk is a key regulator of the microglial contribution to neurodegenerative disease and suggests that Syk inhibitors may be used to prevent excessive microglial phagocytosis of synapses and neurons.
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Affiliation(s)
| | - Guy C. Brown
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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24
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Guha Ray A, Odum OP, Wiseman D, Weinstock A. The diverse roles of macrophages in metabolic inflammation and its resolution. Front Cell Dev Biol 2023; 11:1147434. [PMID: 36994095 PMCID: PMC10041730 DOI: 10.3389/fcell.2023.1147434] [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: 01/18/2023] [Accepted: 02/14/2023] [Indexed: 03/14/2023] Open
Abstract
Macrophages are one of the most functionally diverse immune cells, indispensable to maintain tissue integrity and metabolic health. Macrophages perform a myriad of functions ranging from promoting inflammation, through inflammation resolution to restoring and maintaining tissue homeostasis. Metabolic diseases encompass a growing list of diseases which develop from a mix of genetics and environmental cues leading to metabolic dysregulation and subsequent inflammation. In this review, we summarize the contributions of macrophages to four metabolic conditions-insulin resistance and adipose tissue inflammation, atherosclerosis, non-alcoholic fatty liver disease and neurodegeneration. The role of macrophages is complex, yet they hold great promise as potential therapies to address these growing health concerns.
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Affiliation(s)
| | | | | | - Ada Weinstock
- Section of Genetic Medicine, Department of Medicine, The University of Chicago, Chicago, IL, United States
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25
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Pitts KM, Margeta MA. Myeloid masquerade: Microglial transcriptional signatures in retinal development and disease. Front Cell Neurosci 2023; 17:1106547. [PMID: 36779012 PMCID: PMC9909491 DOI: 10.3389/fncel.2023.1106547] [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: 11/23/2022] [Accepted: 01/12/2023] [Indexed: 01/27/2023] Open
Abstract
Microglia are dynamic guardians of neural tissue and the resident immune cells of the central nervous system (CNS). The disease-associated microglial signature (DAM), also known as the microglial neurodegenerative phenotype (MGnD), has gained significant attention in recent years as a fundamental microglial response common to various neurodegenerative disease pathologies. Interestingly, this signature shares many features in common with developmental microglia, suggesting the existence of recycled gene programs which play a role both in early neural circuit formation as well as in response to aging and disease. In addition, recent advances in single cell RNA sequencing have revealed significant heterogeneity within the original DAM signature, with contributions from both yolk sac-derived microglia as well as bone marrow-derived macrophages. In this review, we examine the role of the DAM signature in retinal development and disease, highlighting crosstalk between resident microglia and infiltrating monocytes which may critically contribute to the underlying mechanisms of age-related neurodegeneration.
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Affiliation(s)
- Kristen M. Pitts
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
- Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, United States
| | - Milica A. Margeta
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
- Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, United States
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26
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Fu X, Feng S, Qin H, Yan L, Zheng C, Yao K. Microglia: The breakthrough to treat neovascularization and repair blood-retinal barrier in retinopathy. Front Mol Neurosci 2023; 16:1100254. [PMID: 36756614 PMCID: PMC9899825 DOI: 10.3389/fnmol.2023.1100254] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 01/03/2023] [Indexed: 01/24/2023] Open
Abstract
Microglia are the primary resident retinal macrophages that monitor neuronal activity in real-time and facilitate angiogenesis during retinal development. In certain retinal diseases, the activated microglia promote retinal angiogenesis in hypoxia stress through neurovascular coupling and guide neovascularization to avascular areas (e.g., the outer nuclear layer and macula lutea). Furthermore, continuously activated microglia secrete inflammatory factors and expedite the loss of the blood-retinal barrier which causes irreversible damage to the secondary death of neurons. In this review, we support microglia can be a potential cellular therapeutic target in retinopathy. We briefly describe the relevance of microglia to the retinal vasculature and blood-retinal barrier. Then we discuss the signaling pathway related to how microglia move to their destinations and regulate vascular regeneration. We summarize the properties of microglia in different retinal disease models and propose that reducing the number of pro-inflammatory microglial death and conversing microglial phenotypes from pro-inflammatory to anti-inflammatory are feasible for treating retinal neovascularization and the damaged blood-retinal barrier (BRB). Finally, we suppose that the unique properties of microglia may aid in the vascularization of retinal organoids.
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Affiliation(s)
- Xuefei Fu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
| | - Shuyu Feng
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
| | - Huan Qin
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
| | - Lin Yan
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
| | - Caiyan Zheng
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
| | - Kai Yao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China,Hubei Province Key Laboratory of Occupational Hazard Identification and Control, Wuhan University of Science and Technology, Wuhan, China,*Correspondence: Kai Yao,
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27
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Microglia in Cultured Porcine Retina: Qualitative Immunohistochemical Analyses of Reactive Microglia in the Outer Retina. Int J Mol Sci 2023; 24:ijms24010871. [PMID: 36614320 PMCID: PMC9820911 DOI: 10.3390/ijms24010871] [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: 11/30/2022] [Revised: 12/26/2022] [Accepted: 12/29/2022] [Indexed: 01/05/2023] Open
Abstract
A late stage of several retinal disorders is retinal detachment, a complication that results in rapid photoreceptor degeneration and synaptic damages. Experimental retinal detachment in vivo is an invasive and complicated method performed on anesthetized animals. As retinal detachment may result in visual impairment and blindness, research is of fundamental importance for understanding degenerative processes. Both morphological and ethical issues make the porcine retina a favorable organotypic model for studies of the degenerative processes that follow retinal detachment. In the cultured retina, photoreceptor degeneration and synaptic injuries develop rapidly and correlate with resident microglial cells' transition into a reactive phenotype. In this immunohistochemical study, we have begun to analyze the transition of subsets of reactive microglia which are known to localize close to the outer plexiform layer (OPL) in degenerating in vivo and in vitro retina. Biomarkers for reactive microglia included P2Ry12, CD63 and CD68 and the general microglial markers were CD11b, Iba1 and isolectin B4 (IB4). The reactive microglia markers labeled microglia subpopulations, suggesting that protective or harmful reactive microglia may be present simultaneously in the injured retina. Our findings support the usage of porcine retina cultures for studies of photoreceptor injuries related to retinal detachment.
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28
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Murenu E, Gerhardt MJ, Biel M, Michalakis S. More than meets the eye: The role of microglia in healthy and diseased retina. Front Immunol 2022; 13:1006897. [PMID: 36524119 PMCID: PMC9745050 DOI: 10.3389/fimmu.2022.1006897] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/11/2022] [Indexed: 11/30/2022] Open
Abstract
Microglia are the main resident immune cells of the nervous system and as such they are involved in multiple roles ranging from tissue homeostasis to response to insults and circuit refinement. While most knowledge about microglia comes from brain studies, some mechanisms have been confirmed for microglia cells in the retina, the light-sensing compartment of the eye responsible for initial processing of visual information. However, several key pieces of this puzzle are still unaccounted for, as the characterization of retinal microglia has long been hindered by the reduced population size within the retina as well as the previous lack of technologies enabling single-cell analyses. Accumulating evidence indicates that the same cell type may harbor a high degree of transcriptional, morphological and functional differences depending on its location within the central nervous system. Thus, studying the roles and signatures adopted specifically by microglia in the retina has become increasingly important. Here, we review the current understanding of retinal microglia cells in physiology and in disease, with particular emphasis on newly discovered mechanisms and future research directions.
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Affiliation(s)
- Elisa Murenu
- Department of Ophthalmology, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany,*Correspondence: Elisa Murenu, ; ; Stylianos Michalakis,
| | | | - Martin Biel
- Department of Pharmacy, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stylianos Michalakis
- Department of Ophthalmology, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany,*Correspondence: Elisa Murenu, ; ; Stylianos Michalakis,
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29
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Ahmad I, Subramani M. Microglia: Friends or Foes in Glaucoma? A Developmental Perspective. Stem Cells Transl Med 2022; 11:1210-1218. [PMID: 36426733 PMCID: PMC9801300 DOI: 10.1093/stcltm/szac077] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 09/29/2022] [Indexed: 11/27/2022] Open
Abstract
Glaucoma is the most prevalent form of optic neuropathy where a progressive degeneration of retinal ganglion cells (RGCs) leads to irreversible loss of vision. The mechanism underlying glaucomatous degeneration remains poorly understood. However, evidence suggests that microglia, which regulate RGC numbers and synaptic integrity during development and provide homeostatic support in adults, may contribute to the disease process. Hence, microglia represent a valid cellular target for therapeutic approaches in glaucoma. Here, we provide an overview of the role of microglia in RGC development and degeneration in the backdrop of neurogenesis and neurodegeneration in the central nervous system and discuss how pathological recapitulation of microglia-mediated developmental mechanisms may help initiate or exacerbate glaucomatous degeneration.
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Affiliation(s)
- Iqbal Ahmad
- Corresponding author: Iqbal Ahmad, Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Murali Subramani
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
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30
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Li S, Wernersbach I, Harms GS, Schäfer MKE. Microglia subtypes show substrate- and time-dependent phagocytosis preferences and phenotype plasticity. Front Immunol 2022. [PMID: 36105813 DOI: 10.3389/fimmu.2022b.945485] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Microglia are phagocytosis-competent CNS cells comprising a spectrum of subtypes with beneficial and/or detrimental functions in acute and chronic neurodegenerative disorders. The heterogeneity of microglia suggests differences in phagocytic activity and phenotype plasticity between microglia subtypes. To study these issues, primary murine glial cultures were cultivated in the presence of serum, different growth factors and cytokines to obtain M0-like, M1-like, and M2-like microglia as confirmed by morphology, M1/M2 gene marker expression, and nitric oxide assay. Single-cell analysis after 3 hours of phagocytosis of E.coli particles or IgG-opsonized beads showed equal internalization by M0-like microglia, whereas M1-like microglia preferably internalized E.coli particles and M2-like microglia preferably internalized IgG beads, suggesting subtype-specific preferences for different phagocytosis substrates. Time-lapse live-cells imaging over 16 hours revealed further differences between microglia subtypes in phagocytosis preference and internalization dynamics. M0- and, more efficiently, M1-like microglia continuously internalized E.coli particles for 16 hours, whereas M2-like microglia discontinued internalization after approximately 8 hours. IgG beads were continuously internalized by M0- and M1-like microglia but strikingly less by M2-like microglia. M2-like microglia initially showed continuous internalization similar to M0-like microglia but again discontinuation of internalization after 8 hours suggesting that the time of substrate exposure differently affect microglia subtypes. After prolonged exposure to E.coli particles or IgG beads for 5 days all microglia subtypes showed increased internalization of E.coli particles compared to IgG beads, increased nitric oxide release and up-regulation of M1 gene markers, irrespectively of the phagocytosis substrate, suggesting phenotype plasticity. In summary, microglia subtypes show substrate- and time-dependent phagocytosis preferences and phenotype plasticity. The results suggest that prolonged phagocytosis substrate exposure enhances M1-like profiles and M2-M1 repolarization of microglia. Similar processes may also take place in conditions of acute and chronic brain insults when microglia encounter different types of phagocytic substrates.
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Affiliation(s)
- Shuailong Li
- Department of Anesthesiology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Isa Wernersbach
- Department of Anesthesiology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Gregory S Harms
- Cell Biology Unit, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany.,Departments of Biology and Physics, Wilkes University, Wilkes Barre, PA, United States
| | - Michael K E Schäfer
- Department of Anesthesiology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany.,Focus Program Translational Neurosciences (FTN), Johannes Gutenberg-University Mainz, Mainz, Germany.,Research Center for Immunotherapy (FZI), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
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31
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Li S, Wernersbach I, Harms GS, Schäfer MKE. Microglia subtypes show substrate- and time-dependent phagocytosis preferences and phenotype plasticity. Front Immunol 2022; 13:945485. [PMID: 36105813 PMCID: PMC9465456 DOI: 10.3389/fimmu.2022.945485] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022] Open
Abstract
Microglia are phagocytosis-competent CNS cells comprising a spectrum of subtypes with beneficial and/or detrimental functions in acute and chronic neurodegenerative disorders. The heterogeneity of microglia suggests differences in phagocytic activity and phenotype plasticity between microglia subtypes. To study these issues, primary murine glial cultures were cultivated in the presence of serum, different growth factors and cytokines to obtain M0-like, M1-like, and M2-like microglia as confirmed by morphology, M1/M2 gene marker expression, and nitric oxide assay. Single-cell analysis after 3 hours of phagocytosis of E.coli particles or IgG-opsonized beads showed equal internalization by M0-like microglia, whereas M1-like microglia preferably internalized E.coli particles and M2-like microglia preferably internalized IgG beads, suggesting subtype-specific preferences for different phagocytosis substrates. Time-lapse live-cells imaging over 16 hours revealed further differences between microglia subtypes in phagocytosis preference and internalization dynamics. M0- and, more efficiently, M1-like microglia continuously internalized E.coli particles for 16 hours, whereas M2-like microglia discontinued internalization after approximately 8 hours. IgG beads were continuously internalized by M0- and M1-like microglia but strikingly less by M2-like microglia. M2-like microglia initially showed continuous internalization similar to M0-like microglia but again discontinuation of internalization after 8 hours suggesting that the time of substrate exposure differently affect microglia subtypes. After prolonged exposure to E.coli particles or IgG beads for 5 days all microglia subtypes showed increased internalization of E.coli particles compared to IgG beads, increased nitric oxide release and up-regulation of M1 gene markers, irrespectively of the phagocytosis substrate, suggesting phenotype plasticity. In summary, microglia subtypes show substrate- and time-dependent phagocytosis preferences and phenotype plasticity. The results suggest that prolonged phagocytosis substrate exposure enhances M1-like profiles and M2-M1 repolarization of microglia. Similar processes may also take place in conditions of acute and chronic brain insults when microglia encounter different types of phagocytic substrates.
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Affiliation(s)
- Shuailong Li
- Department of Anesthesiology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Isa Wernersbach
- Department of Anesthesiology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Gregory S. Harms
- Cell Biology Unit, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
- Departments of Biology and Physics, Wilkes University, Wilkes Barre, PA, United States
| | - Michael K. E. Schäfer
- Department of Anesthesiology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
- Focus Program Translational Neurosciences (FTN), Johannes Gutenberg-University Mainz, Mainz, Germany
- Research Center for Immunotherapy (FZI), University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
- *Correspondence: Michael K. E. Schäfer,
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32
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Li C, Wang Y, Xing Y, Han J, Zhang Y, Zhang A, Hu J, Hua Y, Bai Y. Regulation of microglia phagocytosis and potential involvement of exercise. Front Cell Neurosci 2022; 16:953534. [PMID: 35959472 PMCID: PMC9357882 DOI: 10.3389/fncel.2022.953534] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/29/2022] [Indexed: 12/11/2022] Open
Abstract
Microglia are considered the main phagocytic cells in the central nervous system, remodeling neural circuits by pruning synapses during development. Microglial phagocytosis is also a crucial process in maintaining adult brain homeostasis and clearing potential toxic factors, which are recognized to be associated with neurodegenerative and neuroinflammatory disorders. For example, microglia can engulf amyloid-β plaques, myelin debris, apoptotic cells, and extracellular harmful substances by expressing a variety of specific receptors on the cell surface or by reprogramming intracellular glucose and lipid metabolism processes. Furthermore, physical exercise has been implicated to be one of the non-pharmaceutical treatments for various nervous system diseases, which is closely related to neuroplasticity and microglia functions including proliferation, activation, and phagocytosis. This review focuses on the central regulatory mechanisms related to microglia phagocytosis and the potential role of exercise training in this process.
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Affiliation(s)
- Congqin Li
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yong Wang
- Department of Neurology, Minhang Hospital, Fudan University, Shanghai, China
| | - Ying Xing
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jing Han
- State Key Laboratory of Medical Neurobiology, Department of Integrative Medicine and Neurobiology, Brain Science Collaborative Innovation Center, School of Basic Medical Sciences, Institutes of Brain Science, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Yuqian Zhang
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Anjing Zhang
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jian Hu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yan Hua
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yulong Bai
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
- National Center for Neurological Disorders, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
- *Correspondence: Yulong Bai
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