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Abokyi S, Tse DYY. Age-related driving mechanisms of retinal diseases and neuroprotection by transcription factor EB-targeted therapy. Neural Regen Res 2025; 20:366-377. [PMID: 38819040 DOI: 10.4103/nrr.nrr-d-23-02033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 03/07/2024] [Indexed: 06/01/2024] Open
Abstract
Retinal aging has been recognized as a significant risk factor for various retinal disorders, including diabetic retinopathy, age-related macular degeneration, and glaucoma, following a growing understanding of the molecular underpinnings of their development. This comprehensive review explores the mechanisms of retinal aging and investigates potential neuroprotective approaches, focusing on the activation of transcription factor EB. Recent meta-analyses have demonstrated promising outcomes of transcription factor EB-targeted strategies, such as exercise, calorie restriction, rapamycin, and metformin, in patients and animal models of these common retinal diseases. The review critically assesses the role of transcription factor EB in retinal biology during aging, its neuroprotective effects, and its therapeutic potential for retinal disorders. The impact of transcription factor EB on retinal aging is cell-specific, influencing metabolic reprogramming and energy homeostasis in retinal neurons through the regulation of mitochondrial quality control and nutrient-sensing pathways. In vascular endothelial cells, transcription factor EB controls important processes, including endothelial cell proliferation, endothelial tube formation, and nitric oxide levels, thereby influencing the inner blood-retinal barrier, angiogenesis, and retinal microvasculature. Additionally, transcription factor EB affects vascular smooth muscle cells, inhibiting vascular calcification and atherogenesis. In retinal pigment epithelial cells, transcription factor EB modulates functions such as autophagy, lysosomal dynamics, and clearance of the aging pigment lipofuscin, thereby promoting photoreceptor survival and regulating vascular endothelial growth factor A expression involved in neovascularization. These cell-specific functions of transcription factor EB significantly impact retinal aging mechanisms encompassing proteostasis, neuronal synapse plasticity, energy metabolism, microvasculature, and inflammation, ultimately offering protection against retinal aging and diseases. The review emphasizes transcription factor EB as a potential therapeutic target for retinal diseases. Therefore, it is imperative to obtain well-controlled direct experimental evidence to confirm the efficacy of transcription factor EB modulation in retinal diseases while minimizing its risk of adverse effects.
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Affiliation(s)
- Samuel Abokyi
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region, China
- Research Center for SHARP Vision, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region, China
| | - Dennis Yan-Yin Tse
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region, China
- Research Center for SHARP Vision, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region, China
- Center for Eye and Vision Research, Sha Tin, Hong Kong Special Administrative Region, China
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2
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Matteoli M. The role of microglial TREM2 in development: A path toward neurodegeneration? Glia 2024. [PMID: 38837837 DOI: 10.1002/glia.24574] [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: 01/20/2024] [Revised: 05/11/2024] [Accepted: 05/21/2024] [Indexed: 06/07/2024]
Abstract
The nervous and the immune systems undergo a continuous cross talk, starting from early development and continuing throughout adulthood and aging. Defects in this cross talk contribute to neurodevelopmental and neurodegenerative diseases. Microglia are the resident immune cells in the brain that are primarily involved in this bidirectional communication. Among the microglial genes, trem2 is a key player, controlling the functional state of microglia and being at the forefront of many processes that require interaction between microglia and other brain components, such as neurons and oligodendrocytes. The present review focuses on the early developmental window, describing the early brain processes in which TREM2 is primarily involved, including the modulation of synapse formation and elimination, the control of neuronal bioenergetic states as well as the contribution to myelination processes and neuronal circuit formation. By causing imbalances during these early maturation phases, dysfunctional TREM2 may have a striking impact on the adult brain, making it a more sensitive target for insults occurring during adulthood and aging.
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Affiliation(s)
- Michela Matteoli
- Department of Biomedical Sciences, Humanitas University, Milan, Italy
- Neuro Center, IRCCS Humanitas Research Hospital, Milan, Italy
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3
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Pocock J, Vasilopoulou F, Svensson E, Cosker K. Microglia and TREM2. Neuropharmacology 2024:110020. [PMID: 38821351 DOI: 10.1016/j.neuropharm.2024.110020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/20/2024] [Accepted: 05/28/2024] [Indexed: 06/02/2024]
Abstract
TREM2 is a membrane receptor solely expressed on microglia in normal brain. In this review we outline recent advances in TREM2 biology and its implications for microglial function, with particular emphasis on findings from iPSC-derived microglia (iMG) expressing TREM2 loss-of-function mutations. Alterations in receptor proximal and distal signalling underlie TREM2 risk variants linked to neurodegenerative disease, principally NH-linked FTD, and late-onset AD, but emerging data suggest roles for TREM2 in PD, MS and ALS. TREM2 downstream functions include phagocytosis of myelin debris, amyloid beta peptides, and phosphatidylserine-expressing cells (resulting from damage or stress). Microglial survival, migration, DAMP signalling, inflammasome activation, and intercellular signalling including tau spreading via exosomes, as well as roles for sTREM2 ain protection and as a biomarker are discussed. The role of TREM2 in metabolic homeostasis, and immunometabolic switching are discussed regarding microglial responses to damage and protection. The use of iPSC models to investigate the role of TREM2 in AD, PD, MS, ALS, and other neurodegenerative diseases could prove invaluable due to their ability to recapitulate human pathology, allowing a full understanding of TREM2 and microglial involvement in the underlying disease mechanisms and progression.
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Affiliation(s)
- Jennifer Pocock
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK.
| | - Foteini Vasilopoulou
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Elina Svensson
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Katharina Cosker
- Department of Neuroinflammation, and Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, UK
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4
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Iyer AK, Vermunt L, Mirfakhar FS, Minaya M, Acquarone M, Koppisetti RK, Renganathan A, You SF, Danhash EP, Verbeck A, Galasso G, Lee SM, Marsh J, Nana AL, Spina S, Seeley WW, Grinberg LT, Temple S, Teunissen CE, Sato C, Karch CM. Cell autonomous microglia defects in a stem cell model of frontotemporal dementia. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.15.24307444. [PMID: 38798451 PMCID: PMC11118656 DOI: 10.1101/2024.05.15.24307444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Neuronal dysfunction has been extensively studied as a central feature of neurodegenerative tauopathies. However, across neurodegenerative diseases, there is strong evidence for active involvement of immune cells like microglia in driving disease pathophysiology. Here, we demonstrate that tau mRNA and protein are expressed in microglia in human brains and in human induced pluripotent stem cell (iPSC)-derived microglia like cells (iMGLs). Using iMGLs harboring the MAPT IVS10+16 mutation and isogenic controls, we demonstrate that a tau mutation is sufficient to alter microglial transcriptional states. We discovered that MAPT IVS10+16 microglia exhibit cytoskeletal abnormalities, stalled phagocytosis, disrupted TREM2/TYROBP networks, and altered metabolism. Additionally, we found that secretory factors from MAPT IVS10+16 iMGLs impact neuronal health, reducing synaptic density in neurons. Key features observed in vitro were recapitulated in human brain tissue and cerebrospinal fluid from MAPT mutations carriers. Together, our findings that MAPT IVS10+16 drives cell-intrinsic dysfunction in microglia that impacts neuronal health has major implications for development of therapeutic strategies.
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Affiliation(s)
- Abhirami K. Iyer
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Lisa Vermunt
- Neurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam Neuroscience, VU University, Amsterdam UMC, The Netherlands
| | | | - Miguel Minaya
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Mariana Acquarone
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | | | - Arun Renganathan
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Shih-Feng You
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Emma P. Danhash
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Anthony Verbeck
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Grant Galasso
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Scott M. Lee
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Jacob Marsh
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
| | - Alissa L. Nana
- Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Salvatore Spina
- Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - William W. Seeley
- Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | - Lea T. Grinberg
- Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
- Department of Pathology, University of Sao Paulo
| | | | - Charlotte E. Teunissen
- Neurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam Neuroscience, VU University, Amsterdam UMC, The Netherlands
| | - Chihiro Sato
- Department of Neurology, Washington University in St Louis, St Louis, MO, USA
- The Tracy Family Stable Isotope Labeling Quantitation Center, Washington University in St Louis, St Louis, MO, USA
| | - Celeste M. Karch
- Department of Psychiatry, Washington University in St Louis, St Louis, MO, USA
- Hope Center for Neurological Disorders, Washington University in St Louis, St Louis, MO, USA
- Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA
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5
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Tagliatti E, Desiato G, Mancinelli S, Bizzotto M, Gagliani MC, Faggiani E, Hernández-Soto R, Cugurra A, Poliseno P, Miotto M, Argüello RJ, Filipello F, Cortese K, Morini R, Lodato S, Matteoli M. Trem2 expression in microglia is required to maintain normal neuronal bioenergetics during development. Immunity 2024; 57:86-105.e9. [PMID: 38159572 PMCID: PMC10783804 DOI: 10.1016/j.immuni.2023.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 07/17/2023] [Accepted: 12/05/2023] [Indexed: 01/03/2024]
Abstract
Triggering receptor expressed on myeloid cells 2 (Trem2) is a myeloid cell-specific gene expressed in brain microglia, with variants that are associated with neurodegenerative diseases, including Alzheimer's disease. Trem2 is essential for microglia-mediated synaptic refinement, but whether Trem2 contributes to shaping neuronal development remains unclear. Here, we demonstrate that Trem2 plays a key role in controlling the bioenergetic profile of pyramidal neurons during development. In the absence of Trem2, developing neurons in the hippocampal cornus ammonis (CA)1 but not in CA3 subfield displayed compromised energetic metabolism, accompanied by reduced mitochondrial mass and abnormal organelle ultrastructure. This was paralleled by the transcriptional rearrangement of hippocampal pyramidal neurons at birth, with a pervasive alteration of metabolic, oxidative phosphorylation, and mitochondrial gene signatures, accompanied by a delay in the maturation of CA1 neurons. Our results unveil a role of Trem2 in controlling neuronal development by regulating the metabolic fitness of neurons in a region-specific manner.
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Affiliation(s)
- Erica Tagliatti
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy; Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Genni Desiato
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy
| | - Sara Mancinelli
- Humanitas University, Department of Biomedical Sciences, Via Levi Montalicini 4, Pieve Emanuele 20072 Milan, Italy
| | - Matteo Bizzotto
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy; Humanitas University, Department of Biomedical Sciences, Via Levi Montalicini 4, Pieve Emanuele 20072 Milan, Italy
| | - Maria C Gagliani
- Cellular Electron Microscopy Laboratory, Department of Experimental Medicine (DIMES), Human Anatomy, Università di Genova, Via Antonio de Toni 14, 16132 Genova, Italy
| | - Elisa Faggiani
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy
| | | | - Andrea Cugurra
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy
| | - Paola Poliseno
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy
| | - Matteo Miotto
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy
| | - Rafael J Argüello
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Fabia Filipello
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Katia Cortese
- Cellular Electron Microscopy Laboratory, Department of Experimental Medicine (DIMES), Human Anatomy, Università di Genova, Via Antonio de Toni 14, 16132 Genova, Italy
| | - Raffaella Morini
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy
| | - Simona Lodato
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy; Humanitas University, Department of Biomedical Sciences, Via Levi Montalicini 4, Pieve Emanuele 20072 Milan, Italy
| | - Michela Matteoli
- IRCCS Humanitas Research Hospital, via Manzoni 56, Rozzano, 20089 Milan, Italy; Institute of Neuroscience - National Research Council, 20139 Milan, Italy.
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6
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Michalski C, Wen Z. Leveraging iPSC technology to assess neuro-immune interactions in neurological and psychiatric disorders. Front Psychiatry 2023; 14:1291115. [PMID: 38025464 PMCID: PMC10672983 DOI: 10.3389/fpsyt.2023.1291115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 10/19/2023] [Indexed: 12/01/2023] Open
Abstract
Communication between the immune and the nervous system is essential for human brain development and homeostasis. Disruption of this intricately regulated crosstalk can lead to neurodevelopmental, psychiatric, or neurodegenerative disorders. While animal models have been essential in characterizing the role of neuroimmunity in development and disease, they come with inherent limitations due to species specific differences, particularly with regard to microglia, the major subset of brain resident immune cells. The advent of induced pluripotent stem cell (iPSC) technology now allows the development of clinically relevant models of the central nervous system that adequately reflect human genetic architecture. This article will review recent publications that have leveraged iPSC technology to assess neuro-immune interactions. First, we will discuss the role of environmental stressors such as neurotropic viruses or pro-inflammatory cytokines on neuronal and glial function. Next, we will review how iPSC models can be used to study genetic risk factors in neurological and psychiatric disorders. Lastly, we will evaluate current challenges and future potential for iPSC models in the field of neuroimmunity.
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Affiliation(s)
- Christina Michalski
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, United States
| | - Zhexing Wen
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States
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7
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Li Y, Xu H, Wang H, Yang K, Luan J, Wang S. TREM2: Potential therapeutic targeting of microglia for Alzheimer's disease. Biomed Pharmacother 2023; 165:115218. [PMID: 37517293 DOI: 10.1016/j.biopha.2023.115218] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 08/01/2023] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease, resulting in the loss of cognitive ability and memory. However, there is no specific treatment to mechanistically inhibit the progression of Alzheimer's disease, and most drugs only provide symptom relief and do not fundamentally reverse AD. Current studies show that triggering receptor expressed on myeloid cells 2 (TREM2) is predominantly expressed in microglia of the central nervous system (CNS) and is involved in microglia proliferation, survival, migration and phagocytosis. The current academic view suggests that TREM2 and its ligands have CNS protective effects in AD. Specifically, TREM2 acts by regulating the function of microglia and promoting the clearance of neuronal toxic substances and abnormal proteins by microglia. In addition, TREM2 is also involved in regulating inflammatory response and cell signaling pathways, affecting the immune response and regulatory role of microglia. Although the relationship between TREM2 and Alzheimer's disease has been extensively studied, its specific mechanism of action is not fully understood. The purpose of this review is to provide a comprehensive analysis of the research of TREM2, including its regulation of the inflammatory response, lipid metabolism and phagocytosis in microglia of CNS in AD, and to explore the potential application prospects as well as limitations of targeting TREM2 for the treatment of AD.
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Affiliation(s)
- Yueran Li
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Huifang Xu
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Huifang Wang
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Kui Yang
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Jiajie Luan
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China
| | - Sheng Wang
- Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui Province, China.
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8
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Lee J, Dimitry JM, Song JH, Son M, Sheehan PW, King MW, Travis Tabor G, Goo YA, Lazar MA, Petrucelli L, Musiek ES. Microglial REV-ERBα regulates inflammation and lipid droplet formation to drive tauopathy in male mice. Nat Commun 2023; 14:5197. [PMID: 37626048 PMCID: PMC10457319 DOI: 10.1038/s41467-023-40927-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 08/16/2023] [Indexed: 08/27/2023] Open
Abstract
Alzheimer's disease, the most common age-related neurodegenerative disease, is characterized by tau aggregation and associated with disrupted circadian rhythms and dampened clock gene expression. REV-ERBα is a core circadian clock protein which also serves as a nuclear receptor and transcriptional repressor involved in lipid metabolism and macrophage function. Global REV-ERBα deletion has been shown to promote microglial activation and mitigate amyloid plaque formation. However, the cell-autonomous effects of microglial REV-ERBα in healthy brain and in tauopathy are unexplored. Here, we show that microglial REV-ERBα deletion enhances inflammatory signaling, disrupts lipid metabolism, and causes lipid droplet (LD) accumulation specifically in male microglia. These events impair microglial tau phagocytosis, which can be partially rescued by blockage of LD formation. In vivo, microglial REV-ERBα deletion exacerbates tau aggregation and neuroinflammation in two mouse tauopathy models, specifically in male mice. These data demonstrate the importance of microglial lipid droplets in tau accumulation and reveal REV-ERBα as a therapeutically accessible, sex-dependent regulator of microglial inflammatory signaling, lipid metabolism, and tauopathy.
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Affiliation(s)
- Jiyeon Lee
- Department of Neurology and Center On Biological Rhythms And Sleep, Washington University School of Medicine, St. Louis, MO, USA
| | - Julie M Dimitry
- Department of Neurology and Center On Biological Rhythms And Sleep, Washington University School of Medicine, St. Louis, MO, USA
| | - Jong Hee Song
- Mass Spectrometry Technology Access Center at McDonnell Genome Institute (MTAC@MGI) at Washington University School of Medicine, St. Louis, MO, USA
| | - Minsoo Son
- Mass Spectrometry Technology Access Center at McDonnell Genome Institute (MTAC@MGI) at Washington University School of Medicine, St. Louis, MO, USA
| | - Patrick W Sheehan
- Department of Neurology and Center On Biological Rhythms And Sleep, Washington University School of Medicine, St. Louis, MO, USA
| | - Melvin W King
- Department of Neurology and Center On Biological Rhythms And Sleep, Washington University School of Medicine, St. Louis, MO, USA
| | - G Travis Tabor
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA
| | - Young Ah Goo
- Mass Spectrometry Technology Access Center at McDonnell Genome Institute (MTAC@MGI) at Washington University School of Medicine, St. Louis, MO, USA
| | - Mitchell A Lazar
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Erik S Musiek
- Department of Neurology and Center On Biological Rhythms And Sleep, Washington University School of Medicine, St. Louis, MO, USA.
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Quick JD, Silva C, Wong JH, Lim KL, Reynolds R, Barron AM, Zeng J, Lo CH. Lysosomal acidification dysfunction in microglia: an emerging pathogenic mechanism of neuroinflammation and neurodegeneration. J Neuroinflammation 2023; 20:185. [PMID: 37543564 PMCID: PMC10403868 DOI: 10.1186/s12974-023-02866-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 07/30/2023] [Indexed: 08/07/2023] Open
Abstract
Microglia are the resident innate immune cells in the brain with a major role in orchestrating immune responses. They also provide a frontline of host defense in the central nervous system (CNS) through their active phagocytic capability. Being a professional phagocyte, microglia participate in phagocytic and autophagic clearance of cellular waste and debris as well as toxic protein aggregates, which relies on optimal lysosomal acidification and function. Defective microglial lysosomal acidification leads to impaired phagocytic and autophagic functions which result in the perpetuation of neuroinflammation and progression of neurodegeneration. Reacidification of impaired lysosomes in microglia has been shown to reverse neurodegenerative pathology in Alzheimer's disease. In this review, we summarize key factors and mechanisms contributing to lysosomal acidification impairment and the associated phagocytic and autophagic dysfunction in microglia, and how these defects contribute to neuroinflammation and neurodegeneration. We further discuss techniques to monitor lysosomal pH and therapeutic agents that can reacidify impaired lysosomes in microglia under disease conditions. Finally, we propose future directions to investigate the role of microglial lysosomal acidification in lysosome-mitochondria crosstalk and in neuron-glia interaction for more comprehensive understanding of its broader CNS physiological and pathological implications.
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Affiliation(s)
- Joseph D Quick
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Cristian Silva
- Faculty of Graduate Studies, University of Kelaniya, Kelaniya, Sri Lanka
| | - Jia Hui Wong
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Kah Leong Lim
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Richard Reynolds
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Anna M Barron
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jialiu Zeng
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
| | - Chih Hung Lo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
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10
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Španić Popovački E, Babić Leko M, Langer Horvat L, Brgić K, Vogrinc Ž, Boban M, Klepac N, Borovečki F, Šimić G. Soluble TREM2 Concentrations in the Cerebrospinal Fluid Correlate with the Severity of Neurofibrillary Degeneration, Cognitive Impairment, and Inflammasome Activation in Alzheimer's Disease. Neurol Int 2023; 15:842-856. [PMID: 37489359 PMCID: PMC10366813 DOI: 10.3390/neurolint15030053] [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: 05/22/2023] [Revised: 06/21/2023] [Accepted: 07/05/2023] [Indexed: 07/26/2023] Open
Abstract
BACKGROUND Individuals with specific TREM2 gene variants that encode for a Triggering Receptor Expressed on Myeloid cells 2 have a higher prevalence of Alzheimer's disease (AD). By interacting with amyloid and apolipoproteins, the TREM2 receptor regulates the number of myeloid cells, phagocytosis, and the inflammatory response. Higher TREM2 expression has been suggested to protect against AD. However, it is extremely difficult to comprehend TREM2 signaling in the context of AD. Previous results are variable and show distinct effects on diverse pathological changes in AD, differences between soluble and membrane isoform signaling, and inconsistency between animal models and humans. In addition, the relationship between TREM2 and inflammasome activation pathways is not yet entirely understood. OBJECTIVE This study aimed to determine the relationship between soluble TREM2 (sTREM2) levels in cerebrospinal fluid (CSF) and plasma samples and other indicators of AD pathology. METHODS Using the Enzyme-Linked Immunosorbent Assay (ELISA), we analyzed 98 samples of AD plasma, 35 samples of plasma from individuals with mild cognitive impairment (MCI), and 11 samples of plasma from healthy controls (HC), as well as 155 samples of AD CSF, 90 samples of MCI CSF, and 50 samples of HC CSF. RESULTS CSF sTREM2 levels were significantly correlated with neurofibrillary degeneration, cognitive decline, and inflammasome activity in AD patients. In contrast to plasma sTREM2, CSF sTREM2 levels in the AD group were higher than those in the MCI and HC groups. Moreover, concentrations of sTREM2 in CSF were substantially higher in the MCI group than in the HC group, indicating that CSF sTREM2 levels could be used not only to distinguish between HC and AD patients but also as a biomarker to detect earlier changes in the MCI stage. CONCLUSIONS The results indicate CSF sTREM2 levels reliably predict neurofibrillary degeneration, cognitive decline, and inflammasome activation, and also have a high diagnostic potential for distinguishing diseased from healthy individuals. To add sTREM2 to the list of required AD biomarkers, future studies will need to include a larger number of patients and utilize a standardized methodology.
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Affiliation(s)
- Ena Španić Popovački
- Department of Neuroscience, Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 12, 10000 Zagreb, Croatia
| | - Mirjana Babić Leko
- Department of Neuroscience, Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 12, 10000 Zagreb, Croatia
| | - Lea Langer Horvat
- Department of Neuroscience, Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 12, 10000 Zagreb, Croatia
| | - Klara Brgić
- Department of Neurosurgery, University Hospital Centre Zagreb, Kišpatićeva 12, 10000 Zagreb, Croatia
| | - Željka Vogrinc
- Laboratory for Neurobiochemistry, Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Kišpatićeva 12, 10000 Zagreb, Croatia
| | - Marina Boban
- Department of Neurology, University Hospital Centre Zagreb, Kišpatićeva 12, 10000 Zagreb, Croatia
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
| | - Nataša Klepac
- Department of Neurology, University Hospital Centre Zagreb, Kišpatićeva 12, 10000 Zagreb, Croatia
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
| | - Fran Borovečki
- Department of Neurology, University Hospital Centre Zagreb, Kišpatićeva 12, 10000 Zagreb, Croatia
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
| | - Goran Šimić
- Department of Neuroscience, Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 12, 10000 Zagreb, Croatia
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