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Yin Y, Yang H, Li R, Wu G, Qin Q, Tang Y. A systematic review of the role of TREM2 in Alzheimer's disease. Chin Med J (Engl) 2024; 137:1684-1694. [PMID: 38915213 PMCID: PMC11268819 DOI: 10.1097/cm9.0000000000003000] [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: 12/30/2023] [Indexed: 06/26/2024] Open
Abstract
BACKGROUND Given the established genetic linkage between triggering receptors expressed on myeloid cells 2 (TREM2) and Alzheimer's disease (AD), an expanding research body has delved into the intricate role of TREM2 within the AD context. However, a conflicting landscape of outcomes has emerged from both in vivo and in vitro investigations. This study aimed to elucidate the multifaceted nuances and gain a clearer comprehension of the role of TREM2. METHODS PubMed database was searched spanning from its inception to January 2022. The search criteria took the form of ("Alzheimer's disease" OR "AD") AND ("transgenic mice model" OR "transgenic mouse model") AND ("Triggering receptor expressed on myeloid cells" OR "TREM2"). Inclusion criteria consisted of the following: (1) publication of original studies in English; (2) utilization of transgenic mouse models for AD research; and (3) reports addressing the subject of TREM2. RESULTS A total of 43 eligible articles were identified. Our analysis addresses four pivotal queries concerning the interrelation of TREM2 with microglial function, Aβ accumulation, tau pathology, and inflammatory processes. However, the diverse inquiries posed yielded inconsistent responses. Nevertheless, the inconsistent roles of TREM2 within these AD mouse models potentially hinge upon factors such as age, sex, brain region, model type, and detection methodologies. CONCLUSIONS This review substantiates the evolving understanding of TREM2's disease progression-dependent impacts. Furthermore, it reviews the interplay between TREM2 and its effects across diverse tissues and temporal stages.
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Affiliation(s)
- Yunsi Yin
- Department of Neurology & Innovation Center for Neurological Disorders, Xuanwu Hospital, Capital Medical University, National Center for Neurological Disorders, Beijing 100053, China
| | - Hanchen Yang
- Department of Neurology & Innovation Center for Neurological Disorders, Xuanwu Hospital, Capital Medical University, National Center for Neurological Disorders, Beijing 100053, China
| | - Ruiyang Li
- Department of Neurology & Innovation Center for Neurological Disorders, Xuanwu Hospital, Capital Medical University, National Center for Neurological Disorders, Beijing 100053, China
| | - Guangshan Wu
- Department of Neurology & Innovation Center for Neurological Disorders, Xuanwu Hospital, Capital Medical University, National Center for Neurological Disorders, Beijing 100053, China
| | - Qi Qin
- Department of Neurology & Innovation Center for Neurological Disorders, Xuanwu Hospital, Capital Medical University, National Center for Neurological Disorders, Beijing 100053, China
| | - Yi Tang
- Department of Neurology & Innovation Center for Neurological Disorders, Xuanwu Hospital, Capital Medical University, National Center for Neurological Disorders, Beijing 100053, China
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2
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Brennan FH, Swarts EA, Kigerl KA, Mifflin KA, Guan Z, Noble BT, Wang Y, Witcher KG, Godbout JP, Popovich PG. Microglia promote maladaptive plasticity in autonomic circuitry after spinal cord injury in mice. Sci Transl Med 2024; 16:eadi3259. [PMID: 38865485 DOI: 10.1126/scitranslmed.adi3259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 05/16/2024] [Indexed: 06/14/2024]
Abstract
Robust structural remodeling and synaptic plasticity occurs within spinal autonomic circuitry after severe high-level spinal cord injury (SCI). As a result, normally innocuous visceral or somatic stimuli elicit uncontrolled activation of spinal sympathetic reflexes that contribute to systemic disease and organ-specific pathology. How hyperexcitable sympathetic circuitry forms is unknown, but local cues from neighboring glia likely help mold these maladaptive neuronal networks. Here, we used a mouse model of SCI to show that microglia surrounded active glutamatergic interneurons and subsequently coordinated multi-segmental excitatory synaptogenesis and expansion of sympathetic networks that control immune, neuroendocrine, and cardiovascular functions. Depleting microglia during critical periods of circuit remodeling after SCI prevented maladaptive synaptic and structural plasticity in autonomic networks, decreased the frequency and severity of autonomic dysreflexia, and prevented SCI-induced immunosuppression. Forced turnover of microglia in microglia-depleted mice restored structural and functional indices of pathological dysautonomia, providing further evidence that microglia are key effectors of autonomic plasticity. Additional data show that microglia-dependent autonomic plasticity required expression of triggering receptor expressed on myeloid cells 2 (Trem2) and α2δ-1-dependent synaptogenesis. These data suggest that microglia are primary effectors of autonomic neuroplasticity and dysautonomia after SCI in mice. Manipulating microglia may be a strategy to limit autonomic complications after SCI or other forms of neurologic disease.
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Affiliation(s)
- Faith H Brennan
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Department of Biomedical and Molecular Sciences and Center for Neuroscience Studies, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Emily A Swarts
- Department of Biomedical and Molecular Sciences and Center for Neuroscience Studies, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Kristina A Kigerl
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Katherine A Mifflin
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Zhen Guan
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Benjamin T Noble
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Yan Wang
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Kristina G Witcher
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Institute for Behavioral Medicine Research, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Jonathan P Godbout
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Institute for Behavioral Medicine Research, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Phillip G Popovich
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Institute for Behavioral Medicine Research, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
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3
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Shi Q, Gutierrez RA, Bhat MA. Microglia, Trem2, and Neurodegeneration. Neuroscientist 2024:10738584241254118. [PMID: 38769824 DOI: 10.1177/10738584241254118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Microglia are a specialized type of neuroimmune cells that undergo morphological and molecular changes through multiple signaling pathways in response to pathological protein aggregates, neuronal death, tissue injury, or infections. Microglia express Trem2, which serves as a receptor for a multitude of ligands enhancing their phagocytic activity. Trem2 has emerged as a critical modulator of microglial activity, especially in many neurodegenerative disorders. Human TREM2 mutations are associated with an increased risk of developing Alzheimer disease (AD) and other neurodegenerative diseases. Trem2 plays dual roles in neuroinflammation and more specifically in disease-associated microglia. Most recent developments on the molecular mechanisms of Trem2, emphasizing its role in uptake and clearance of amyloid β (Aβ) aggregates and other tissue debris to help protect and preserve the brain, are encouraging. Although Trem2 normally stimulates defense mechanisms, its dysregulation can intensify inflammation, which poses major therapeutic challenges. Recent therapeutic approaches targeting Trem2 via agonistic antibodies and gene therapy methodologies present possible avenues for reducing the burden of neurodegenerative diseases. This review highlights the promise of Trem2 as a therapeutic target, especially for Aβ-associated AD, and calls for more mechanistic investigations to understand the context-specific role of microglial Trem2 in developing effective therapies against neurodegenerative diseases.
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Affiliation(s)
- Qian Shi
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Raul A Gutierrez
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
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4
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Lan G, Chen X, Yang J, Sun P, Cai Y, Li A, Zhu Y, Liu Z, Ma S, Guo T. Microglial Reactivity Correlates with Presynaptic Loss Independent of β-Amyloid and Tau. Ann Neurol 2024; 95:917-928. [PMID: 38356322 PMCID: PMC11060909 DOI: 10.1002/ana.26885] [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: 10/12/2023] [Revised: 12/29/2023] [Accepted: 01/26/2024] [Indexed: 02/16/2024]
Abstract
OBJECTIVE Triggering receptor expressed on myeloid cells-2 (TREM2) and progranulin (PGRN) are critical regulators of microglia activation and can be detected in cerebrospinal fluid (CSF). However, whether microglial reactivity is detrimental or neuroprotective for Alzheimer disease (AD) is still debatable. METHODS We identified 663 participants with baseline β-amyloid (Aβ) positron emission tomography (PET) and CSF biomarker data, including phosphorylated tau181 (p-Tau181), soluble TREM2 (sTREM2), PGRN, and growth-associated protein-43 (GAP-43). Among them, 254 participants had concurrent longitudinal CSF biomarkers. We used multivariate regression analysis to study the associations of CSF microglial biomarkers with Aβ PET, CSF p-Tau181, and CSF GAP-43 cross-sectionally and longitudinally. A Chinese aging cohort's independent CSF samples (n = 65) were analyzed as a validation. RESULTS Higher baseline levels of CSF microglial biomarkers were related to faster rates of CSF sTREM2 increase and CSF PGRN decrease. Elevated CSF p-Tau181 was associated with higher levels of CSF microglial biomarkers and faster rates of CSF sTREM2 increase and CSF PGRN decrease. In both cohorts, higher Aβ burden was associated with attenuated CSF p-Tau181 effects on CSF microglial biomarker increases. Independent of Aβ PET and CSF p-Tau181 pathologies, higher levels of CSF sTREM2 but not CSF PGRN were related to elevated CSF GAP-43 levels and faster rates of CSF GAP-43 increase. INTERPRETATION These findings suggest that higher Aβ burden may attenuate the p-Tau-associated microglial responses, and TREM2-related microglial reactivity may independently correlate with GAP-43-related presynaptic loss. This study highlights the two-edged role of microglial reactivity in AD and other neurodegenerative diseases. ANN NEUROL 2024;95:917-928.
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Affiliation(s)
- Guoyu Lan
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen, China, 518000
| | - Xuhui Chen
- Department of Neurology, Peking University Shenzhen Hospital, Shenzhen, China, 518000
| | - Jie Yang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
| | - Pan Sun
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen, China, 518000
| | - Yue Cai
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
| | - Anqi Li
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
| | - Yalin Zhu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
| | - Zhen Liu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
| | | | - Shaohua Ma
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen, China, 518000
| | - Tengfei Guo
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China, 518000
- Department of Neurology, Peking University Shenzhen Hospital, Shenzhen, China, 518000
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Sun MK, Alkon DL. Alzheimer's therapeutic development: shifting neurodegeneration to neuroregeneration. Trends Pharmacol Sci 2024; 45:197-209. [PMID: 38360510 PMCID: PMC10939773 DOI: 10.1016/j.tips.2024.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/13/2024] [Accepted: 01/22/2024] [Indexed: 02/17/2024]
Abstract
Alzheimer's disease (AD), similar to AD-related dementias, is characterized by impaired/lost neuronal structures and functions due to a long progression of neurodegeneration. Derailed endogenous signal pathways and disease processes have critical roles in neurodegeneration and are pharmacological targets in inducing neuroregeneration. Pharmacologically switching/shifting the brain status from neurodegeneration to neuroregeneration is emerging as a new therapeutic concept, one that is not only achievable, but also essential for effective therapy for AD. The results of the pharmacological-induced shift from neurodegeneration to neuroregeneration are twofold: arresting cognitive deterioration (and directing the brain toward cognitive recovery) in established AD, and preventing neurodegeneration through building up cognitive resilience in patients with preclinical or probable AD. In this review, we discuss these new developments in AD pharmacology and relevant clinical trials.
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Affiliation(s)
- Miao-Kun Sun
- Synaptogenix, Inc., 1185 Avenue of the Americas, 3rd Floor, New York, NY 10036, USA.
| | - Daniel L Alkon
- Synaptogenix, Inc., 1185 Avenue of the Americas, 3rd Floor, New York, NY 10036, USA
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Zgorzynska E. TREM2 in Alzheimer's disease: Structure, function, therapeutic prospects, and activation challenges. Mol Cell Neurosci 2024; 128:103917. [PMID: 38244651 DOI: 10.1016/j.mcn.2024.103917] [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: 08/03/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/22/2024] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a membrane glycoprotein that plays a crucial role in the regulation of microglial survival, activation, phagocytosis, as well as in the maintenance of brain homeostasis and the inflammatory response to injury or neurodegeneration. This review provides a comprehensive overview of TREM2 structure and functions, highlighting the role of its variants in the development and progression of Alzheimer's disease (AD), a devastating neurodegenerative disease that affects millions of people worldwide. Additionally, the article discusses the potential of TREM2 as a therapeutic target in AD, analyzing the current state of research and future prospects. Given the significant challenges associated with the activation of TREM2, particularly due to its diverse isoforms and the delicate balance required to modulate the immune response without triggering hyperactivation, this review aims to enhance our understanding of TREM2 in AD and inspire further research into this promising yet challenging therapeutic target.
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Affiliation(s)
- Emilia Zgorzynska
- Department of Cell-to-Cell Communication, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland.
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7
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Wen L, Bi D, Shen Y. Complement-mediated synapse loss in Alzheimer's disease: mechanisms and involvement of risk factors. Trends Neurosci 2024; 47:135-149. [PMID: 38129195 DOI: 10.1016/j.tins.2023.11.010] [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: 06/20/2023] [Revised: 10/25/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023]
Abstract
The complement system is increasingly recognized as a key player in the synapse loss and cognitive impairments observed in Alzheimer's disease (AD). In particular, the process of complement-dependent synaptic pruning through phagocytosis is over-activated in AD brains, driving detrimental excessive synapse elimination and contributing to synapse loss, which is the strongest neurobiological correlate of cognitive impairments in AD. Herein we review recent advances in characterizing complement-mediated synapse loss in AD, summarize the underlying mechanisms, and discuss the possible involvement of AD risk factors such as aging and various risk genes. We conclude with an overview of key questions that remain to be addressed.
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Affiliation(s)
- Lang Wen
- Department of Neurology and Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Neurodegenerative Disease Research Center, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Danlei Bi
- Department of Neurology and Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Neurodegenerative Disease Research Center, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China; Anhui Province Key Laboratory of Biomedical Aging Research, University of Science and Technology of China, Hefei, 230026, China; Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, 230026, China; CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230026, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Yong Shen
- Department of Neurology and Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Neurodegenerative Disease Research Center, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China; Anhui Province Key Laboratory of Biomedical Aging Research, University of Science and Technology of China, Hefei, 230026, China; CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 230026, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
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8
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Zhang L, Yao Q, Hu J, Qiu B, Xiao Y, Zhang Q, Zeng Y, Zheng S, Zhang Y, Wan Y, Zheng X, Zeng Q. Hotspots and trends of microglia in Alzheimer's disease: a bibliometric analysis during 2000-2022. Eur J Med Res 2024; 29:75. [PMID: 38268044 PMCID: PMC10807212 DOI: 10.1186/s40001-023-01602-9] [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: 10/29/2023] [Accepted: 12/17/2023] [Indexed: 01/26/2024] Open
Abstract
BACKGROUND Alzheimer's disease is one common type of dementia. Numerous studies have suggested a correlation between Alzheimer's disease and inflammation. Microglia mainly participate in the inflammatory response in the brain. Currently, ample evidence has shown that microglia are closely related to the occurrence and development of Alzheimer's disease. OBJECTIVE We opted for bibliometric analysis to comprehensively summarize the advancements in the study of microglia in Alzheimer's disease, aiming to provide researchers with current trends and future research directions. METHODS All articles and reviews pertaining to microglia in Alzheimer's disease from 2000 to 2022 were downloaded through Web of Science Core Collection. The results were subjected to bibliometric analysis using VOSviewer 1.6.18 and CiteSpace 6.1 R2. RESULTS Overall, 7449 publications were included. The number of publications was increasing yearly. The United States has published the most publications. Harvard Medical School has published the most papers of all institutions. Journal of Alzheimer's Disease and Journal of Neuroscience were the journals with the most studies and the most commonly cited, respectively. Mt Heneka is the author with the highest productivity and co-citation. After analysis, the most common keywords are neuroinflammation, amyloid-beta, inflammation, neurodegeneration. Gut microbiota, extracellular vesicle, dysfunction and meta-analysis are the hotspots of research at the present stage and are likely to continue. CONCLUSION NLRP3 inflammasome, TREM2, gut microbiota, mitochondrial dysfunction, exosomes are research hotspots. The relationship between microglia-mediated neuroinflammation and Alzheimer's disease have been the focus of current research and the development trend of future research.
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Affiliation(s)
- Lijie Zhang
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China
| | - Qiuru Yao
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Nursing, Southern Medical University, Guangzhou, China
| | - Jinjing Hu
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China
| | - Baizhi Qiu
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Nursing, Southern Medical University, Guangzhou, China
| | - Yupeng Xiao
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China
| | - Qi Zhang
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China
| | - Yuting Zeng
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Shuqi Zheng
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China
| | - Youao Zhang
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Yantong Wan
- College of Anesthesiology, Southern Medical University, Guangzhou, China.
| | - Xiaoyan Zheng
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China.
| | - Qing Zeng
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China.
- School of Rehabilitation Sciences, Southern Medical University, Guangzhou, China.
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9
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Batista AF, Khan KA, Papavergi MT, Lemere CA. The Importance of Complement-Mediated Immune Signaling in Alzheimer's Disease Pathogenesis. Int J Mol Sci 2024; 25:817. [PMID: 38255891 PMCID: PMC10815224 DOI: 10.3390/ijms25020817] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 01/05/2024] [Accepted: 01/07/2024] [Indexed: 01/24/2024] Open
Abstract
As an essential component of our innate immune system, the complement system is responsible for our defense against pathogens. The complement cascade has complex roles in the central nervous system (CNS), most of what we know about it stems from its role in brain development. However, in recent years, numerous reports have implicated the classical complement cascade in both brain development and decline. More specifically, complement dysfunction has been implicated in neurodegenerative disorders, such as Alzheimer's disease (AD), which is the most common form of dementia. Synapse loss is one of the main pathological hallmarks of AD and correlates with memory impairment. Throughout the course of AD progression, synapses are tagged with complement proteins and are consequently removed by microglia that express complement receptors. Notably, astrocytes are also capable of secreting signals that induce the expression of complement proteins in the CNS. Both astrocytes and microglia are implicated in neuroinflammation, another hallmark of AD pathogenesis. In this review, we provide an overview of previously known and newly established roles for the complement cascade in the CNS and we explore how complement interactions with microglia, astrocytes, and other risk factors such as TREM2 and ApoE4 modulate the processes of neurodegeneration in both amyloid and tau models of AD.
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Affiliation(s)
- André F. Batista
- Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (A.F.B.); (K.A.K.); (M.-T.P.)
| | - Khyrul A. Khan
- Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (A.F.B.); (K.A.K.); (M.-T.P.)
| | - Maria-Tzousi Papavergi
- Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (A.F.B.); (K.A.K.); (M.-T.P.)
- School for Mental Health and Neuroscience (MHeNs), Department of Psychiatry and Neuropsychology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Cynthia A. Lemere
- Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (A.F.B.); (K.A.K.); (M.-T.P.)
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10
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Vecchiarelli HA, Lopes LT, Paolicelli RC, Stevens B, Wake H, Tremblay MÈ. Synapse Regulation. ADVANCES IN NEUROBIOLOGY 2024; 37:179-208. [PMID: 39207693 DOI: 10.1007/978-3-031-55529-9_11] [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 are the resident immune cells of the brain. As such, they rapidly detect changes in normal brain homeostasis and accurately respond by fine-tuning in a tightly regulated manner their morphology, gene expression, and functional behavior. Depending on the nature of these changes, microglia can thicken and retract their processes, proliferate and migrate, release numerous signaling factors and compounds influencing neuronal physiology (e.g., cytokines and trophic factors), in addition to secreting proteases able to transform the extracellular matrix, and phagocytosing various types of cellular debris, etc. Because microglia also transform rapidly (on a time scale of minutes) during experimental procedures, studying these very special cells requires methods that are specifically non-invasive. The development of such methods has provided unprecedented insights into the roles of microglia during normal physiological conditions. In particular, transcranial two-photon in vivo imaging revealed that presumably "resting" microglia continuously survey the brain parenchyma with their highly motile processes, in addition to modulating their structural and functional interactions with neuronal circuits along the changes in neuronal activity and behavioral experience occurring throughout the lifespan. In this chapter, we will describe how surveillant microglia interact with synaptic elements and modulate the number, maturation, function, and plasticity of synapses in the healthy developing, mature, and aging brain, with consequences on neuronal activity, learning and memory, and the behavioral outcome.
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Affiliation(s)
| | | | - Rosa C Paolicelli
- Division of Psychiatry Research, University of Zurich, Schlieren, Switzerland
| | - Beth Stevens
- Department of Neurology, Harvard Medical School, Center for Life Science, Boston Children's Hospital, F.M. Kirby Neurobiology Center, Boston, MA, USA
| | - Hiroaki Wake
- Division of Brain Circuits, National Institute for Basic Biology, Myodaiji-cho, Okazaki, Japan
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada.
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11
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Shi J, Huang S. Comparative Insight into Microglia/Macrophages-Associated Pathways in Glioblastoma and Alzheimer's Disease. Int J Mol Sci 2023; 25:16. [PMID: 38203185 PMCID: PMC10778632 DOI: 10.3390/ijms25010016] [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: 11/08/2023] [Revised: 12/09/2023] [Accepted: 12/14/2023] [Indexed: 01/12/2024] Open
Abstract
Microglia and macrophages are pivotal to the brain's innate immune response and have garnered considerable attention in the context of glioblastoma (GBM) and Alzheimer's disease (AD) research. This review delineates the complex roles of these cells within the neuropathological landscape, focusing on a range of signaling pathways-namely, NF-κB, microRNAs (miRNAs), and TREM2-that regulate the behavior of tumor-associated macrophages (TAMs) in GBM and disease-associated microglia (DAMs) in AD. These pathways are critical to the processes of neuroinflammation, angiogenesis, and apoptosis, which are hallmarks of GBM and AD. We concentrate on the multifaceted regulation of TAMs by NF-κB signaling in GBM, the influence of TREM2 on DAMs' responses to amyloid-beta deposition, and the modulation of both TAMs and DAMs by GBM- and AD-related miRNAs. Incorporating recent advancements in molecular biology, immunology, and AI techniques, through a detailed exploration of these molecular mechanisms, we aim to shed light on their distinct and overlapping regulatory functions in GBM and AD. The review culminates with a discussion on how insights into NF-κB, miRNAs, and TREM2 signaling may inform novel therapeutic approaches targeting microglia and macrophages in these neurodegenerative and neoplastic conditions. This comparative analysis underscores the potential for new, targeted treatments, offering a roadmap for future research aimed at mitigating the progression of these complex diseases.
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Affiliation(s)
- Jian Shi
- Department of Neurology, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA 94121, USA
| | - Shiwei Huang
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN 55455, USA
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12
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Sudwarts A, Thinakaran G. Alzheimer's genes in microglia: a risk worth investigating. Mol Neurodegener 2023; 18:90. [PMID: 37986179 PMCID: PMC10662636 DOI: 10.1186/s13024-023-00679-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 11/07/2023] [Indexed: 11/22/2023] Open
Abstract
Despite expressing many key risk genes, the role of microglia in late-onset Alzheimer's disease pathophysiology is somewhat ambiguous, with various phenotypes reported to be either harmful or protective. Herein, we review some key findings from clinical and animal model investigations, discussing the role of microglial genetics in mediating perturbations from homeostasis. We note that impairment to protective phenotypes may include prolonged or insufficient microglial activation, resulting in dysregulated metabolomic (notably lipid-related) processes, compounded by age-related inflexibility in dynamic responses. Insufficiencies of mouse genetics and aggressive transgenic modelling imply severe limitations in applying current methodologies for aetiological investigations. Despite the shortcomings, widely used amyloidosis and tauopathy models of the disease have proven invaluable in dissecting microglial functional responses to AD pathophysiology. Some recent advances have brought modelling tools closer to human genetics, increasing the validity of both aetiological and translational endeavours.
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Affiliation(s)
- Ari Sudwarts
- Byrd Alzheimer's Center and Research Institute, University of South Florida, Tampa, FL, 33613, USA.
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
| | - Gopal Thinakaran
- Byrd Alzheimer's Center and Research Institute, University of South Florida, Tampa, FL, 33613, USA.
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
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13
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Armstrong MJ, Jin Y, Vattathil SM, Huang Y, Schroeder JP, Bennet DA, Qin ZS, Wingo TS, Jin P. Role of TET1-mediated epigenetic modulation in Alzheimer's disease. Neurobiol Dis 2023; 185:106257. [PMID: 37562656 PMCID: PMC10530206 DOI: 10.1016/j.nbd.2023.106257] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/30/2023] [Accepted: 08/07/2023] [Indexed: 08/12/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder influenced by a complex interplay of environmental, epigenetic, and genetic factors. DNA methylation (5mC) and hydroxymethylation (5hmC) are DNA modifications that serve as tissue-specific and temporal regulators of gene expression. TET family enzymes dynamically regulate these epigenetic modifications in response to environmental conditions, connecting environmental factors with gene expression. Previous epigenetic studies have identified 5mC and 5hmC changes associated with AD. In this study, we performed targeted resequencing of TET1 on a cohort of early-onset AD (EOAD) and control samples. Through gene-wise burden analysis, we observed significant enrichment of rare TET1 variants associated with AD (p = 0.04). We also profiled 5hmC in human postmortem brain tissues from AD and control groups. Our analysis identified differentially hydroxymethylated regions (DhMRs) in key genes responsible for regulating the methylome: TET3, DNMT3L, DNMT3A, and MECP2. To further investigate the role of Tet1 in AD pathogenesis, we used the 5xFAD mouse model with a Tet1 KO allele to examine how Tet1 loss influences AD pathogenesis. We observed significant changes in neuropathology, 5hmC, and RNA expression associated with Tet1 loss, while the behavioral alterations were not significant. The loss of Tet1 significantly increased amyloid plaque burden in the 5xFAD mouse (p = 0.044) and lead to a non-significant trend towards exacerbated AD-associated stress response in 5xFAD mice. At the molecular level, we found significant DhMRs enriched in genes involved in pathways responsible for neuronal projection organization, dendritic spine development and organization, and myelin assembly. RNA-Seq analysis revealed a significant increase in the expression of AD-associated genes such as Mpeg1, Ctsd, and Trem2. In conclusion, our results suggest that TET enzymes, particularly TET1, which regulate the methylome, may contribute to AD pathogenesis, as the loss of TET function increases AD-associated pathology.
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Affiliation(s)
- Matthew J Armstrong
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Yulin Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Selina M Vattathil
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Yanting Huang
- Department of Computer Science, Emory University, Atlanta, GA 30322, USA
| | - Jason P Schroeder
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David A Bennet
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL 60612, USA
| | - Zhaohui S Qin
- Department of Biostatistics and Bioinformatics, Emory University Rollins School of Public Health, Atlanta, GA 30322, USA
| | - Thomas S Wingo
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
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14
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Wu X, Gao Y, Shi C, Tong J, Ma D, Shen J, Yang J, Ji M. Complement C1q drives microglia-dependent synaptic loss and cognitive impairments in a mouse model of lipopolysaccharide-induced neuroinflammation. Neuropharmacology 2023; 237:109646. [PMID: 37356797 DOI: 10.1016/j.neuropharm.2023.109646] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 06/19/2023] [Accepted: 06/22/2023] [Indexed: 06/27/2023]
Abstract
Activated microglia and subsequent release of pro-inflammatory cytokines result in neuroinflammatory status which further damage neurological function including cognitive impairments in various neurological conditions. However, the underlying molecular mechanisms during these pathological processing remain unknown. In the current study, mice received intraperitoneal administrations of LPS (0.5 mg/kg, daily, Escherichia coli O55:B5) for seven consecutive days and their different cohorts were used for behavioral assessment with open field, Y maze, and novel object recognition test or for electrophysiology recordings of mEPSC, LFP or LTP in in vivo or ex vivo preparation. The hippocampus from some cohorts were harvested for immunostaining or Western blotting of c1q, Iba-1, CD68, PSD95 and dendritic spine density or for transcriptome and proteomics analysis. Repeated LPS injections induced an up-regulation of complement system protein c1q and distinct microglial phenotype with an enrichment of the complement-phagosome pathway. Microglial synaptic engulfment and profound synaptic loss were found. These pathological changes were accompanied with the significantly decreased excitatory synaptic transmission, disturbed theta oscillations, impaired hippocampal long-term potentiation, and cognitive impairments. Notably, neutralization of c1q signaling robustly prevented these changes. Collectively, our data provide evidence that activated microglia and complement cascade c1q signaling in the hippocampus may account for synaptic loss and cognitive impairments in a mouse model of neuroinflammation induced by repeated LPS injections. Our work implicates that complement system may be a therapeutic target for developing therapies to prevent or treat cognitive disorders related to neuroinflammation or other disease conditions including neurodegenerative disease per se.
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Affiliation(s)
- Xinmiao Wu
- Department of Anesthesiology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yuzhu Gao
- Department of Anesthesiology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Cuina Shi
- Department of Anesthesiology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jianhua Tong
- Department of Anesthesiology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Daqing Ma
- Division of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, UK
| | - Jinchun Shen
- Department of Anesthesiology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China.
| | - Jianjun Yang
- Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
| | - Muhuo Ji
- Department of Anesthesiology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
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15
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Abstract
As resident immune cells of the brain, microglia serve pivotal roles in regulating neuronal function under both physiological and pathological conditions, including aging and the most prevalent neurodegenerative disease, Alzheimer's disease (AD). Instructed by neurons, microglia regulate synaptic function and guard brain homeostasis throughout life. Dysregulation of microglial function, however, can lead to dire consequences, including aggravated cognitive decline during aging and exacerbated neuropathology in diseases. The triggering receptor expressed on myeloid cells 2 (TREM2) is a key regulator of microglial function. Loss-of-function variants of TREM2 are associated with an increased risk of AD. TREM2 orchestrates the switch of microglial transcriptome programming that modulates microglial chemotaxis, phagocytosis, and inflammatory responses, as well as microglial regulation of synaptic function in health and disease. Intriguingly, the outcome of microglial/TREM2 function is influenced by age and the context of neuropathology. This review summarizes the rapidly growing research on TREM2 under physiological conditions and in AD, particularly highlighting the impact of TREM2 on neuronal function.
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Affiliation(s)
- Wenhui Qu
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN 55455
| | - Ling Li
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN 55455
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN 55455
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16
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Sun Y, Che J, Zhang J. Emerging non-proinflammatory roles of microglia in healthy and diseased brains. Brain Res Bull 2023; 199:110664. [PMID: 37192719 DOI: 10.1016/j.brainresbull.2023.110664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 04/04/2023] [Accepted: 05/13/2023] [Indexed: 05/18/2023]
Abstract
Microglia, the resident myeloid cells of the central nervous system, are the first line of defense against foreign pathogens, thereby confining the extent of brain injury. However, the role of microglia is not limited to macrophage-like functions. In addition to proinflammatory response mediation, microglia are involved in neurodevelopmental remodeling and homeostatic maintenance in the absence of disease. An increasing number of studies have also elucidated microglia-mediated regulation of tumor growth and neural repair in diseased brains. Here, we review the non-proinflammatory roles of microglia, with the aim of promoting a deeper understanding of the functions of microglia in healthy and diseased brains and contributing to the development of novel therapeutics that target microglia in neurological disorders.
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Affiliation(s)
- Yinying Sun
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, 200032, Shanghai China.
| | - Ji Che
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, 200032, Shanghai China.
| | - Jun Zhang
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, 200032, Shanghai China; Department of Oncology, Shanghai Medical College, Fudan University, 200032, Shanghai China.
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17
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Qu W, Canoll P, Hargus G. Molecular Insights into Cell Type-specific Roles in Alzheimer's Disease: Human Induced Pluripotent Stem Cell-based Disease Modelling. Neuroscience 2023; 518:10-26. [PMID: 35569647 PMCID: PMC9974106 DOI: 10.1016/j.neuroscience.2022.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/04/2022] [Accepted: 05/06/2022] [Indexed: 10/18/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia resulting in widespread degeneration of the central nervous system with severe cognitive impairment. Despite the devastating toll of AD, the incomplete understanding of the complex molecular mechanisms hinders the expeditious development of effective cures. Emerging evidence from animal studies has shown that different brain cell types play distinct roles in the pathogenesis of AD. Glutamatergic neurons are preferentially affected in AD and pronounced gliosis contributes to the progression of AD in both a cell-autonomous and a non-cell-autonomous manner. Much has been discovered through genetically modified animal models, yet frequently failed translational attempts to clinical applications call for better disease models. Emerging evidence supports the significance of human-induced pluripotent stem cell (iPSC) derived brain cells in modeling disease development and progression, opening new avenues for the discovery of molecular mechanisms. This review summarizes the function of different cell types in the pathogenesis of AD, such as neurons, microglia, and astrocytes, and recognizes the potential of utilizing the rapidly growing iPSC technology in modeling AD.
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Affiliation(s)
- Wenhui Qu
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, United States
| | - Peter Canoll
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States
| | - Gunnar Hargus
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, United States.
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18
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Popescu AS, Butler CA, Allendorf DH, Piers TM, Mallach A, Roewe J, Reinhardt P, Cinti A, Redaelli L, Boudesco C, Pradier L, Pocock JM, Thornton P, Brown GC. Alzheimer's disease-associated R47H TREM2 increases, but wild-type TREM2 decreases, microglial phagocytosis of synaptosomes and neuronal loss. Glia 2023; 71:974-990. [PMID: 36480007 PMCID: PMC10952257 DOI: 10.1002/glia.24318] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/22/2022] [Accepted: 11/25/2022] [Indexed: 12/14/2022]
Abstract
Triggering receptor on myeloid cells 2 (TREM2) is an innate immune receptor, upregulated on the surface of microglia associated with amyloid plaques in Alzheimer's disease (AD). Individuals heterozygous for the R47H variant of TREM2 have greatly increased risk of developing AD. We examined the effects of wild-type (WT), R47H and knock-out (KO) of human TREM2 expression in three microglial cell systems. Addition of mouse BV-2 microglia expressing R47H TREM2 to primary mouse neuronal cultures caused neuronal loss, not observed with WT TREM2. Neuronal loss was prevented by using annexin V to block exposed phosphatidylserine, an eat-me signal and ligand of TREM2, suggesting loss was mediated by microglial phagocytosis of neurons exposing phosphatidylserine. Addition of human CHME-3 microglia expressing R47H TREM2 to LUHMES neuronal-like cells also caused loss compared to WT TREM2. Expression of R47H TREM2 in BV-2 and CHME-3 microglia increased their uptake of phosphatidylserine-beads and synaptosomes versus WT TREM2. Human iPSC-derived microglia with heterozygous R47H TREM2 had increased phagocytosis of synaptosomes vs common-variant TREM2. Additionally, phosphatidylserine liposomes increased activation of human iPSC-derived microglia expressing homozygous R47H TREM2 versus common-variant TREM2. Finally, overexpression of TREM2 in CHME-3 microglia caused increased expression of cystatin F, a cysteine protease inhibitor, and knock-down of cystatin F increased CHME-3 uptake of phosphatidylserine-beads. Together, these data suggest that R47H TREM2 may increase AD risk by increasing phagocytosis of synapses and neurons via greater activation by phosphatidylserine and that WT TREM2 may decrease microglial phagocytosis of synapses and neurons via cystatin F.
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Affiliation(s)
- Alma S. Popescu
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - Claire A. Butler
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Neuroscience, BioPharmaceuticals R&DAstraZenecaCambridgeUK
| | | | - Thomas M. Piers
- Department of NeuroinflammationUCL Queen Square Institute of NeurologyLondonUK
| | - Anna Mallach
- Department of NeuroinflammationUCL Queen Square Institute of NeurologyLondonUK
| | - Julian Roewe
- Neuroscience DiscoveryAbbVie Deutschland GmbH & Co. KGLudwigshafenGermany
| | - Peter Reinhardt
- Neuroscience DiscoveryAbbVie Deutschland GmbH & Co. KGLudwigshafenGermany
| | | | | | | | | | - Jennifer M. Pocock
- Department of NeuroinflammationUCL Queen Square Institute of NeurologyLondonUK
| | - Peter Thornton
- Neuroscience, BioPharmaceuticals R&DAstraZenecaCambridgeUK
| | - Guy C. Brown
- Department of BiochemistryUniversity of CambridgeCambridgeUK
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19
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Liu Y, Shen X, Zhang Y, Zheng X, Cepeda C, Wang Y, Duan S, Tong X. Interactions of glial cells with neuronal synapses, from astrocytes to microglia and oligodendrocyte lineage cells. Glia 2023; 71:1383-1401. [PMID: 36799296 DOI: 10.1002/glia.24343] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 02/18/2023]
Abstract
The mammalian brain is a complex organ comprising neurons, glia, and more than 1 × 1014 synapses. Neurons are a heterogeneous group of electrically active cells, which form the framework of the complex circuitry of the brain. However, glial cells, which are primarily divided into astrocytes, microglia, oligodendrocytes (OLs), and oligodendrocyte precursor cells (OPCs), constitute approximately half of all neural cells in the mammalian central nervous system (CNS) and mainly provide nutrition and tropic support to neurons in the brain. In the last two decades, the concept of "tripartite synapses" has drawn great attention, which emphasizes that astrocytes are an integral part of the synapse and regulate neuronal activity in a feedback manner after receiving neuronal signals. Since then, synaptic modulation by glial cells has been extensively studied and substantially revised. In this review, we summarize the latest significant findings on how glial cells, in particular, microglia and OL lineage cells, impact and remodel the structure and function of synapses in the brain. Our review highlights the cellular and molecular aspects of neuron-glia crosstalk and provides additional information on how aberrant synaptic communication between neurons and glia may contribute to neural pathologies.
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Affiliation(s)
- Yao Liu
- Songjiang Institute and Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xi Shen
- Songjiang Institute and Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuhan Zhang
- College of Basic Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoli Zheng
- Songjiang Institute and Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Yao Wang
- Department of Assisted Reproduction, The Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shumin Duan
- Songjiang Institute and Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, Zhejiang University, Hangzhou, China
| | - Xiaoping Tong
- Songjiang Institute and Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, China
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20
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Zhu Y, Yan P, Wang R, Lai J, Tang H, Xiao X, Yu R, Bao X, Zhu F, Wang K, Lu Y, Dang J, Zhu C, Zhang R, Dang W, Zhang B, Fu Q, Zhang Q, Kang C, Chen Y, Chen X, Liang Q, Wang K. Opioid-induced fragile-like regulatory T cells contribute to withdrawal. Cell 2023; 186:591-606.e23. [PMID: 36669483 DOI: 10.1016/j.cell.2022.12.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 09/04/2022] [Accepted: 12/19/2022] [Indexed: 01/20/2023]
Abstract
Dysregulation of the immune system is a cardinal feature of opioid addiction. Here, we characterize the landscape of peripheral immune cells from patients with opioid use disorder and from healthy controls. Opioid-associated blood exhibited an abnormal distribution of immune cells characterized by a significant expansion of fragile-like regulatory T cells (Tregs), which was positively correlated with the withdrawal score. Analogously, opioid-treated mice also showed enhanced Treg-derived interferon-γ (IFN-γ) expression. IFN-γ signaling reshaped synaptic morphology in nucleus accumbens (NAc) neurons, modulating subsequent withdrawal symptoms. We demonstrate that opioids increase the expression of neuron-derived C-C motif chemokine ligand 2 (Ccl2) and disrupted blood-brain barrier (BBB) integrity through the downregulation of astrocyte-derived fatty-acid-binding protein 7 (Fabp7), which both triggered peripheral Treg infiltration into NAc. Our study demonstrates that opioids drive the expansion of fragile-like Tregs and favor peripheral Treg diapedesis across the BBB, which leads to IFN-γ-mediated synaptic instability and subsequent withdrawal symptoms.
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Affiliation(s)
- Yongsheng Zhu
- National Biosafety Evidence Foundation, Bio-evidence Sciences Academy, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, Xi'an, Shaanxi 710115, China
| | - Peng Yan
- National Biosafety Evidence Foundation, Bio-evidence Sciences Academy, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, Xi'an, Shaanxi 710115, China
| | - Rui Wang
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; School of Informatics, Xiamen University, Xiamen, Fujian 361005, China
| | - Jianghua Lai
- National Biosafety Evidence Foundation, Bio-evidence Sciences Academy, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, Xi'an, Shaanxi 710115, China
| | - Hua Tang
- Xi'an International Medical Center Hospital, Xi'an, Shaanxi 710117, China
| | - Xu Xiao
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; School of Informatics, Xiamen University, Xiamen, Fujian 361005, China
| | - Rongshan Yu
- National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; School of Informatics, Xiamen University, Xiamen, Fujian 361005, China
| | - Xiaorui Bao
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Feng Zhu
- Center for Translational Medicine, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
| | - Kena Wang
- National Biosafety Evidence Foundation, Bio-evidence Sciences Academy, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, Xi'an, Shaanxi 710115, China
| | - Ye Lu
- National Biosafety Evidence Foundation, Bio-evidence Sciences Academy, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, Xi'an, Shaanxi 710115, China
| | - Jie Dang
- School of Basic Medicine, Ningxia Medical University, Yinchuan, Ningxia 750004, China
| | - Chao Zhu
- Department of Nephrology, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| | - Rui Zhang
- Department of Emergency Medicine, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Wei Dang
- The Sixth Ward, Xi'an Mental Health Center, Xi'an, Shannxi 710100, China
| | - Bao Zhang
- National Biosafety Evidence Foundation, Bio-evidence Sciences Academy, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, Xi'an, Shaanxi 710115, China
| | - Quanze Fu
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Qian Zhang
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Chongao Kang
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Yujie Chen
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Xiaoyu Chen
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China
| | - Qing Liang
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
| | - Kejia Wang
- Fujian Provincial Key Laboratory of Organ and Tissue Regeneration, Xiamen Key Laboratory of Regeneration Medicine, Organ Transplantation Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China; National Institute for Data Science in Health and Medicine, School of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
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21
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TREM2 and Microglia Contribute to the Synaptic Plasticity: from Physiology to Pathology. Mol Neurobiol 2023; 60:512-523. [PMID: 36318443 DOI: 10.1007/s12035-022-03100-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 10/20/2022] [Indexed: 11/07/2022]
Abstract
Synapses are bridges for information transmission in the central nervous system (CNS), and synaptic plasticity is fundamental for the normal function of synapses, contributing substantially to learning and memory. Numerous studies have proven that microglia can participate in the occurrence and progression of neurodegenerative diseases (NDDs), such as Alzheimer's disease (AD), by regulating synaptic plasticity. In this review, we summarize the main characteristics of synapses and synaptic plasticity under physiological and pathological conditions. We elaborate the origin and development of microglia and the two well-known microglial signaling pathways that regulate synaptic plasticity. We also highlight the unique role of triggering receptor expressed on myeloid cells 2 (TREM2) in microglia-mediated regulation of synaptic plasticity and its relationship with AD. Finally, we propose four possible ways in which TREM2 is involved in regulating synaptic plasticity. This review will help researchers understand how NDDs develop from the perspective of synaptic plasticity.
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22
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Qu W, Jeong A, Zhong R, Thieschafer JS, Gram A, Li L. Deletion of Small GTPase H-Ras Rescues Memory Deficits and Reduces Amyloid Plaque-Associated Dendritic Spine Loss in Transgenic Alzheimer's Mice. Mol Neurobiol 2023; 60:495-511. [PMID: 36287323 PMCID: PMC10771223 DOI: 10.1007/s12035-022-03082-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/27/2022] [Indexed: 01/25/2023]
Abstract
Alzheimer's disease (AD) is a fatal neurodegenerative disorder, affecting millions of lives without a cure. While the molecular mechanism of AD remains obscure, emerging evidence suggests that small GTPases, a group of GTP-binding proteins that regulate a plethora of essential cellular events, modulate the pathogenic process of AD. Among those, the small GTPase H-Ras, extensively studied in cancer, regulates synaptic function, and both upstream and downstream signaling pathways of H-Ras have been implicated in AD. However, the role of H-Ras per se in AD pathogenesis had not been explored previously. In the present study, the impact of Hras deletion on cognitive function and amyloid pathology was investigated in transgenic APP/PS1 mice of AD. Behavioral assessments showed that the absence of Hras rescued spatial memory deficit in APP/PS1 mice at 9 months of age. The pathological evaluation demonstrated that Hras deletion reduced cortical amyloid deposition and astrogliosis. Furthermore, Hras deficiency protected against amyloid plaque-associated loss of dendritic spines in APP/PS1 mice. Intriguingly, canonical signaling pathways downstream of H-Ras were not affected by the absence of Hras in the brain. Unbiased transcriptomic analysis revealed that lack of H-Ras affected the expression of select genes in the brain of AD mice and identified a novel connection between H-Ras and Annexin A4, a calcium-dependent phospholipid-binding protein that has been shown to regulate membrane repair, neuroinflammation, and calcium homeostasis. Taken together, these data indicate that H-Ras modifies the pathogenic process of AD and may serve as a potential therapeutic target for AD.
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Affiliation(s)
- Wenhui Qu
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
- Department of Pathology & Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Angela Jeong
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Rui Zhong
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Josslen S Thieschafer
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Andrea Gram
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ling Li
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA.
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA.
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23
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Qiao W, Chen Y, Zhong J, Madden BJ, Charlesworth CM, Martens YA, Liu CC, Knight J, Ikezu TC, Kurti A, Zhu Y, Meneses A, Rosenberg CL, Kuchenbecker LA, Vanmaele LK, Li F, Chen K, Shue F, Dacquel MV, Fryer J, Pandey A, Zhao N, Bu G. Trem2 H157Y increases soluble TREM2 production and reduces amyloid pathology. Mol Neurodegener 2023; 18:8. [PMID: 36721205 PMCID: PMC9890893 DOI: 10.1186/s13024-023-00599-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 01/19/2023] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND The rare p.H157Y variant of TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) was found to increase Alzheimer's disease (AD) risk. This mutation is located at the cleavage site of TREM2 extracellular domain. Ectopic expression of TREM2-H157Y in HEK293 cells resulted in increased TREM2 shedding. However, the physiological outcomes of the TREM2 H157Y mutation remain unknown in the absence and presence of AD related pathologies. METHODS We generated a novel Trem2 H157Y knock-in mouse model through CRISPR/Cas9 technology and investigated the effects of Trem2 H157Y on TREM2 proteolytic processing, synaptic function, and AD-related amyloid pathologies by conducting biochemical assays, targeted mass spectrometry analysis of TREM2, hippocampal electrophysiology, immunofluorescent staining, in vivo micro-dialysis, and cortical bulk RNA sequencing. RESULTS Consistent with previous in vitro findings, Trem2 H157Y increases TREM2 shedding with elevated soluble TREM2 levels in the brain and serum. Moreover, Trem2 H157Y enhances synaptic plasticity without affecting microglial density and morphology, or TREM2 signaling. In the presence of amyloid pathology, Trem2 H157Y accelerates amyloid-β (Aβ) clearance and reduces amyloid burden, dystrophic neurites, and gliosis in two independent founder lines. Targeted mass spectrometry analysis of TREM2 revealed higher ratios of soluble to full-length TREM2-H157Y compared to wild-type TREM2, indicating that the H157Y mutation promotes TREM2 shedding in the presence of Aβ. TREM2 signaling was further found reduced in Trem2 H157Y homozygous mice. Transcriptomic profiling revealed that Trem2 H157Y downregulates neuroinflammation-related genes and an immune module correlated with the amyloid pathology. CONCLUSION Taken together, our findings suggest beneficial effects of the Trem2 H157Y mutation in synaptic function and in mitigating amyloid pathology. Considering the genetic association of TREM2 p.H157Y with AD risk, we speculate TREM2 H157Y in humans might increase AD risk through an amyloid-independent pathway, such as its effects on tauopathy and neurodegeneration which merit further investigation.
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Affiliation(s)
- Wenhui Qiao
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Yixing Chen
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Jun Zhong
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905 USA
| | - Benjamin J. Madden
- Medical Genome Facility, Proteomics Core, Mayo Clinic, Rochester, MN USA
| | | | - Yuka A. Martens
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Chia-Chen Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Joshua Knight
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | | | - Aishe Kurti
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Yiyang Zhu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Axel Meneses
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | | | | | - Lucy K. Vanmaele
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Fuyao Li
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Kai Chen
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Francis Shue
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | | | - John Fryer
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ 85259 USA
| | - Akhilesh Pandey
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905 USA
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN USA
- Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104 India
| | - Na Zhao
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
- SciNeuro Pharmaceuticals, Rockville, MD 20805 USA
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24
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Tan S, Gao H, Sun J, Li N, Zhang Y, Yang L, Wang M, Wang Q, Zhai Q. CD33/TREM2 Signaling Mediates Sleep Deprivation-Induced Memory Impairment by Regulating Microglial Phagocytosis. Neuromolecular Med 2023:10.1007/s12017-023-08733-6. [PMID: 36639554 DOI: 10.1007/s12017-023-08733-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 01/04/2023] [Indexed: 01/15/2023]
Abstract
Sleep deprivation causes significant memory impairment in healthy adults. Extensive research has focused on identifying the biological mechanisms underlying memory impairment. Microglia-mediated synaptic elimination plays an indispensable role in sleep deprivation. Here, the potential role of the CD33/TREM2 signaling pathway in modulating memory decline during chronic sleep restriction (CSR) was evaluated. In this study, adult male C57BL/6 mice were sleep-restricted using an automated sleep deprivation apparatus for 20 h per day for 7 days. The Y-maze test revealed that spontaneous alternation was significantly reduced in CSR mice compared with control mice. The percentage of exploratory preference for the novel object in CSR mice was significantly decreased compared with that in control mice. These memory deficits correlated with aberrant microglial activation and increased phagocytic ability. Moreover, in CSR mice, the CD33 protein level in hippocampal tissue was significantly downregulated, but the TREM2 protein level was increased. In BV2 microglial cells, downregulation of CD33 increased TREM2 expression and improved microglial phagocytosis. Then, the sialic ligand monosialo-ganglioside 1 (GM1, 20 mg/kg, i.p.) was administered to mice once a day during CSR. Our results further showed that GM1 activated CD33 and consequently disturbed TREM2-mediated microglial phagocytosis. Finally, GM1 reversed CSR-induced synaptic loss and memory impairment via the CD33/TREM2 signaling pathway in the CA1 region of the hippocampus. This study provides novel evidence that activating CD33 and/or inhibiting TREM2 activity represent potential therapies for sleep loss-induced memory deficits through the modulation of microglial phagocytosis.
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Affiliation(s)
- Shuwen Tan
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Hui Gao
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Jianyu Sun
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Na Li
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Yuxin Zhang
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Liu Yang
- Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Min Wang
- Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, China
| | - Qiang Wang
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
| | - Qian Zhai
- Department of Anesthesiology and Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
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25
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Altered expression of microglial markers of phagocytosis in schizophrenia. Schizophr Res 2023; 251:22-29. [PMID: 36527956 DOI: 10.1016/j.schres.2022.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/07/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022]
Abstract
BACKGROUND Cognitive disturbances in schizophrenia have been linked to a lower density of dendritic spines on pyramidal neurons in the prefrontal cortex (PFC). Complement component C4, which has previously been found at higher levels in schizophrenia, marks synapses for phagocytosis by microglia. Thus, elevated consumption of dendritic spines by microglia mediated through excessive complement activity may play a role in lower spine density in schizophrenia. However, it is unclear if microglia themselves have the molecular capacity for enhanced phagocytosis of spines in schizophrenia. METHODS Transcript levels for complement components and microglia-specific phagocytic markers were quantified using quantitative PCR in the PFC of 62 matched pairs of schizophrenia and unaffected comparison subjects and in antipsychotic-exposed monkeys. RESULTS Relative to comparison subjects, schizophrenia subjects had higher mRNA levels for C4 (+154 %); C1q (+69 %), which initiates the classical complement pathway that includes C4; and for microglia-specific markers that enable phagocytic activity including TAM receptor tyrosine kinases Axl (+27 %) and MerTK (+27 %) and lysosome-associated glycoprotein CD68 (+27 %) (all p ≤ .042). Transcript levels for microglial phagocytic markers were correlated with C4 mRNA levels in schizophrenia subjects (all r ≥ 0.31, p ≤ .015). We also found further evidence consistent with microglial activation in schizophrenia, including higher mRNA levels for THIK1 (TWIK-related halothane-inhibited potassium channel: +30 %) and lower mRNA levels for the purinergic receptor P2Y12 (-27 %) (all p ≤ .016). Transcript levels were unchanged in antipsychotic-exposed monkeys. CONCLUSIONS These results are consistent with the presence of increased complement activity and an elevated molecular capacity of microglia for phagocytosis in the same schizophrenia subjects.
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26
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Kawabata S. Excessive/Aberrant and Maladaptive Synaptic Plasticity: A Hypothesis for the Pathogenesis of Alzheimer’s Disease. Front Aging Neurosci 2022; 14:913693. [PMID: 35865745 PMCID: PMC9294348 DOI: 10.3389/fnagi.2022.913693] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/08/2022] [Indexed: 01/01/2023] Open
Abstract
The amyloid hypothesis for the pathogenesis of Alzheimer’s disease (AD) is widely accepted. Last year, the US Food and Drug Administration considered amyloid-β peptide (Aβ) as a surrogate biomarker and approved an anti-Aβ antibody, aducanumab, although its effectiveness in slowing the progression of AD is still uncertain. This approval has caused a great deal of controversy. Opinions are divided about whether there is enough evidence to definitely consider Aβ as a causative substance of AD. To develop this discussion constructively and to discover the most suitable therapeutic interventions in the end, an alternative persuasive hypothesis needs to emerge to better explain the facts. In this paper, I propose a hypothesis that excessive/aberrant and maladaptive synaptic plasticity is the pathophysiological basis for AD.
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27
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Qin Q, Wang M, Yin Y, Tang Y. The Specific Mechanism of TREM2 Regulation of Synaptic Clearance in Alzheimer's Disease. Front Immunol 2022; 13:845897. [PMID: 35663962 PMCID: PMC9160359 DOI: 10.3389/fimmu.2022.845897] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 04/19/2022] [Indexed: 01/31/2023] Open
Abstract
Alzheimer’s disease (AD) is a progressive neurodegenerative disease. Synaptic dysfunction is an integral feature of AD pathophysiology and a significant factor in early cognitive impairment in AD. Microglia, which are intrinsic immune cells in the central nervous system, play important regulatory roles in the process of synapse formation. Microglia can refine synaptic connections through synaptic clearance to ensure accurate synaptic transmission. Synaptic clearance is not only existed during central nervous system development but also aberrantly activated during AD pathology. However, the mechanisms of synaptic clearance in AD remain to be investigated. TREM2 is involved in the synaptic clearance of microglia, acting alone or with other molecules, such as apolipoprotein E (APOE). In addition, C1q is essential for microglia-mediated synaptic clearance. In this review, we systematically summarized the potential mechanisms of microglia involved in synaptic clearance, comprehensively reviewed the role of TREM2 in microglia regulating synaptic clearance and proposed our hypothesis that TREM2 interacts with APOE and C1q to promote synaptic clearance. This review provides new insights into the role of TREM2 regulation in microglia synaptic clearance and provides potential prospects for the treatment of AD.
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Affiliation(s)
- Qi Qin
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,National Center for Neurological Disorders, National Clinical Research Center for Geriatric Diseases, Beijing, China
| | - Meng Wang
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yunsi Yin
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yi Tang
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,National Center for Neurological Disorders, National Clinical Research Center for Geriatric Diseases, Beijing, China
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28
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Chronic exposure of alcohol triggers microglia-mediated synaptic elimination inducing cognitive impairment. Exp Neurol 2022; 353:114061. [DOI: 10.1016/j.expneurol.2022.114061] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/10/2022] [Accepted: 03/27/2022] [Indexed: 11/21/2022]
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29
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Liu H, Jin M, Ji M, Zhang W, Liu A, Wang T. Hypoxic pretreatment of adipose-derived stem cell exosomes improved cognition by delivery of circ-Epc1 and shifting microglial M1/M2 polarization in an Alzheimer's disease mice model. Aging (Albany NY) 2022; 14:3070-3083. [PMID: 35366241 PMCID: PMC9037259 DOI: 10.18632/aging.203989] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 02/24/2022] [Indexed: 11/25/2022]
Abstract
Alzheimer's disease (AD) is the most common dementia in the world. Increasing evidence has shown that exosomes from hypoxic pretreated adipose-derived stem cells (ADSCs) could be an effective cognitive function therapeutic in AD-associated pathophysiology. However, their role and regulatory mechanism remain largely unknown. High-throughput sequencing was used to identify differentially expressed circRNAs from ADSCs or hypoxia pretreated ADSC exosomes. Luciferase reporter assays and RT-qPCR were used to investigate the relationships between circ-Epc1, miR-770-3p, and TREM2. APP/PS1 double transgenic AD model mice were then used to study therapeutic effects regarding circ-Epc1 in ADSC exosomes. BV2 cells were used to show the regulatory relationships between circ-Epc1, miR-770-3p, and TREM2 and to show how these interactions modulated phenotypic transformations and inflammatory cytokine expressions in microglia. The results showed that exosomes from hypoxia pretreated ADSCs had a good therapeutic effect on improving cognitive functions by decreasing neuronal damage in the hippocampus. High-throughput sequencing showed that circ-Epc1 played an important role in hypoxia-pretreated ADSC exosomes regarding their ability to improve cognitive functions. Luciferase reporter assays showed that TREM2 and miR-770-3p were downstream targets of circ-Epc1. Overexpressing miR-770-3p or downregulating TREM2 reversed the effects of circ-Epc1 on M2 microglia during lipopolysaccharide treatment. In vivo experiments showed that circ-Epc1-containing ADSC exosomes increased the therapeutic effect of exosomes by improving cognitive function, decreasing neuronal damage, and shifting hippocampal microglia from the M1 polarization to the M2 polarization stages. Taken together, the data show that hypoxic pretreatment of ADSC exosomes improved cognition by delivery of circ-Epc1 and by shifting microglial M1/M2 polarization in an AD mouse model.
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Affiliation(s)
- Haining Liu
- Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China.,Alzheimer's Disease and Related Disorders Center, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Mingming Jin
- Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai 201318, China
| | - Minxiu Ji
- Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China.,Alzheimer's Disease and Related Disorders Center, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Wei Zhang
- Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China.,Alzheimer's Disease and Related Disorders Center, Shanghai Jiao Tong University, Shanghai 200030, China
| | - An Liu
- Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China.,Alzheimer's Disease and Related Disorders Center, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Tao Wang
- Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China.,Alzheimer's Disease and Related Disorders Center, Shanghai Jiao Tong University, Shanghai 200030, China
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30
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Han X, Liu YJ, Liu BW, Ma ZL, Xia TJ, Gu XP. TREM2 and CD163 Ameliorate Microglia-Mediated Inflammatory Environment in the Aging Brain. J Mol Neurosci 2022; 72:1075-1084. [PMID: 35306602 DOI: 10.1007/s12031-022-01965-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/02/2022] [Indexed: 11/28/2022]
Abstract
Aging decreases cognitive functions, especially learning and memory. Neuroinflammation is mediated by microglia and occurs in age-related neurodegenerative diseases. The expression profiles in a dataset of cognitively normal controls (GSE11882) were obtained from the Gene Expression Omnibus (GEO) database. Microarray data were used to explore the expression of age-related genes in the human hippocampus. A total of 120 differentially expressed genes (DEGs) were identified and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. A protein-protein interaction (PPI) network was constructed. A total of 18 key genes were identified by the plugin cytoHubba in Cytoscape software. Two genes with a positive impact on cognition during aging were teased out: triggering receptor expressed on myeloid cells 2 (TREM2) and a scavenger receptor (CD163). Finally, the results of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB) verified that the mRNA expression of these two genes was significantly upregulated in aged mice. Moreover, the levels of the inflammatory factors IL-1β and IL-6 were significantly increased. TREM2 and CD163 may be upregulated to alleviate the inflammatory environment resulting from microglial activation in the aging brain, thereby delaying cognitive decline.
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Affiliation(s)
- Xue Han
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, 210008, Jiangsu, China
| | - Yu-Jia Liu
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, 210008, Jiangsu, China
| | - Bin-Wen Liu
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, 210008, Jiangsu, China
| | - Zheng-Liang Ma
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, 210008, Jiangsu, China.
| | - Tian-Jiao Xia
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, 210008, Jiangsu, China. .,Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Xiao-Ping Gu
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, 210008, Jiangsu, China.
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31
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Chataigner M, Lucas C, Di Miceli M, Pallet V, Laye S, Mehaignerie A, Bouvret E, Dinel AL, Joffre C. Dietary Fish Hydrolysate Improves Memory Performance Through Microglial Signature Remodeling During Aging. Front Nutr 2021; 8:750292. [PMID: 34888336 PMCID: PMC8650686 DOI: 10.3389/fnut.2021.750292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/01/2021] [Indexed: 12/28/2022] Open
Abstract
Brain aging is characterized by a chronic low-grade inflammation, which significantly impairs cognitive function. Microglial cells, the immunocompetent cells of the brain, present a different phenotype, switching from a homeostatic signature (M0) to a more reactive phenotype called “MGnD” (microglial neurodegenerative phenotype), leading to a high production of pro-inflammatory cytokines. Furthermore, microglial cells can be activated by age-induced gut dysbiosis through the vagus nerve or the modulation of the peripheral immune system. Nutrients, in particular n-3 long chain polyunsaturated fatty acids (LC-PUFAs) and low molecular weight peptides, display powerful immunomodulatory properties, and can thus prevent age-related cognitive decline. The objective of this study was to investigate the effects of n-3 LC-PUFAs and low molecular weight peptides contained in a marine by-product-derived hydrolysate on microglial phenotypes and intestinal permeability and their consequences on cognition in mice. We demonstrated that the hydrolysate supplementation for 8 weeks prevented short- and long-term memory decline during aging. These observations were linked to the modulation of microglial signature. Indeed, the hydrolysate supplementation promoted homeostatic microglial phenotype by increasing TGF-β1 expression and stimulated phagocytosis by increasing Clec7a expression. Moreover, the hydrolysate supplementation promoted anti-inflammatory intestinal pathway and tended to prevent intestinal permeability alteration occurring during aging. Therefore, the fish hydrolysate appears as an interesting candidate to prevent cognitive decline during aging.
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Affiliation(s)
- Mathilde Chataigner
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, Bordeaux, France.,Abyss Ingredients, Caudan, France
| | - Céline Lucas
- NutriBrain Research and Technology Transfer, NutriNeuro, Bordeaux, France
| | - Mathieu Di Miceli
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, Bordeaux, France.,Worcester Biomedical Research Group, School of Science and the Environment, University of Worcester, Worcester, United Kingdom
| | - Véronique Pallet
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, Bordeaux, France
| | - Sophie Laye
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, Bordeaux, France
| | | | | | - Anne-Laure Dinel
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, Bordeaux, France.,NutriBrain Research and Technology Transfer, NutriNeuro, Bordeaux, France
| | - Corinne Joffre
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, Bordeaux, France
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32
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Yan Y, Aierken A, Wang C, Song D, Ni J, Wang Z, Quan Z, Qing H. A potential biomarker of preclinical Alzheimer's disease: The olfactory dysfunction and its pathogenesis-based neural circuitry impairments. Neurosci Biobehav Rev 2021; 132:857-869. [PMID: 34810025 DOI: 10.1016/j.neubiorev.2021.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/26/2021] [Accepted: 11/07/2021] [Indexed: 01/24/2023]
Abstract
The olfactory dysfunction can signal and act as a potential biomarker of preclinical AD. However, the precise regulatory mechanism of olfactory function on the neural pathogenesis of AD is still unclear. The impairment of neural networks in olfaction system has been shown to be tightly associated with AD. As key brain regions of the olfactory system, the olfactory bulb (OB) and the piriform cortex (PCx) have a profound influence on the olfactory function. Therefore, this review will explore the mechanism of olfactory dysfunction in preclinical AD in the perspective of abnormal neural networks in the OB and PCx and their associated brain regions, especially from two aspects of aberrant oscillations and synaptic plasticity damages, which help better understand the underlying mechanism of olfactory neural network damages related to AD.
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Affiliation(s)
- Yan Yan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Ailikemu Aierken
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Chunjian Wang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Da Song
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Junjun Ni
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Zhe Wang
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, The National Clinical Research Center for Geriatric Disease, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Zhenzhen Quan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
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Borst K, Dumas AA, Prinz M. Microglia: Immune and non-immune functions. Immunity 2021; 54:2194-2208. [PMID: 34644556 DOI: 10.1016/j.immuni.2021.09.014] [Citation(s) in RCA: 253] [Impact Index Per Article: 84.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/20/2021] [Accepted: 09/16/2021] [Indexed: 12/21/2022]
Abstract
As resident macrophages of the central nervous system (CNS), microglia are associated with diverse functions essential to the developing and adult brain during homeostasis and disease. They are aided in their tasks by intricate bidirectional communication with other brain cells under steady-state conditions as well as with infiltrating peripheral immune cells during perturbations. Harmonious cell-cell communication involving microglia are considered crucial to maintain the healthy state of the tissue environment and to overcome pathology such as neuroinflammation. Analyses of such intercellular pathways have contributed to our understanding of the heterogeneous but context-associated microglial responses to environmental cues across neuropathology, including inflammatory conditions such as infections and autoimmunity, as well as immunosuppressive states as seen in brain tumors. Here, we summarize the latest evidence demonstrating how these interactions drive microglia immune and non-immune functions, which coordinate the transition from homeostatic to disease-related cellular states.
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Affiliation(s)
- Katharina Borst
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany.
| | - Anaelle Aurelie Dumas
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany.
| | - Marco Prinz
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany; Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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Cornell J, Salinas S, Huang HY, Zhou M. Microglia regulation of synaptic plasticity and learning and memory. Neural Regen Res 2021; 17:705-716. [PMID: 34472455 PMCID: PMC8530121 DOI: 10.4103/1673-5374.322423] [Citation(s) in RCA: 163] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Microglia are the resident macrophages of the central nervous system. Microglia possess varied morphologies and functions. Under normal physiological conditions, microglia mainly exist in a resting state and constantly monitor their microenvironment and survey neuronal and synaptic activity. Through the C1q, C3 and CR3 “Eat Me” and CD47 and SIRPα “Don’t Eat Me” complement pathways, as well as other pathways such as CX3CR1 signaling, resting microglia regulate synaptic pruning, a process crucial for the promotion of synapse formation and the regulation of neuronal activity and synaptic plasticity. By mediating synaptic pruning, resting microglia play an important role in the regulation of experience-dependent plasticity in the barrel cortex and visual cortex after whisker removal or monocular deprivation, and also in the regulation of learning and memory, including the modulation of memory strength, forgetfulness, and memory quality. As a response to brain injury, infection or neuroinflammation, microglia become activated and increase in number. Activated microglia change to an amoeboid shape, migrate to sites of inflammation and secrete proteins such as cytokines, chemokines and reactive oxygen species. These molecules released by microglia can lead to synaptic plasticity and learning and memory deficits associated with aging, Alzheimer’s disease, traumatic brain injury, HIV-associated neurocognitive disorder, and other neurological or mental disorders such as autism, depression and post-traumatic stress disorder. With a focus mainly on recently published literature, here we reviewed the studies investigating the role of resting microglia in synaptic plasticity and learning and memory, as well as how activated microglia modulate disease-related plasticity and learning and memory deficits. By summarizing the function of microglia in these processes, we aim to provide an overview of microglia regulation of synaptic plasticity and learning and memory, and to discuss the possibility of microglia manipulation as a therapeutic to ameliorate cognitive deficits associated with aging, Alzheimer’s disease, traumatic brain injury, HIV-associated neurocognitive disorder, and mental disorders.
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Affiliation(s)
- Jessica Cornell
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Shelbi Salinas
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Hou-Yuan Huang
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Miou Zhou
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
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Jeong A, Cheng S, Zhong R, Bennett DA, Bergö MO, Li L. Protein farnesylation is upregulated in Alzheimer's human brains and neuron-specific suppression of farnesyltransferase mitigates pathogenic processes in Alzheimer's model mice. Acta Neuropathol Commun 2021; 9:129. [PMID: 34315531 PMCID: PMC8314463 DOI: 10.1186/s40478-021-01231-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/16/2021] [Indexed: 11/10/2022] Open
Abstract
The pathogenic mechanisms underlying the development of Alzheimer's disease (AD) remain elusive and to date there are no effective prevention or treatment for AD. Farnesyltransferase (FT) catalyzes a key posttranslational modification process called farnesylation, in which the isoprenoid farnesyl pyrophosphate is attached to target proteins, facilitating their membrane localization and their interactions with downstream effectors. Farnesylated proteins, including the Ras superfamily of small GTPases, are involved in regulating diverse physiological and pathological processes. Emerging evidence suggests that isoprenoids and farnesylated proteins may play an important role in the pathogenesis of AD. However, the dynamics of FT and protein farnesylation in human brains and the specific role of neuronal FT in the pathogenic progression of AD are not known. Here, using postmortem brain tissue from individuals with no cognitive impairment (NCI), mild cognitive impairment (MCI), or Alzheimer's dementia, we found that the levels of FT and membrane-associated H-Ras, an exclusively farnesylated protein, and its downstream effector ERK were markedly increased in AD and MCI compared with NCI. To elucidate the specific role of neuronal FT in AD pathogenesis, we generated the transgenic AD model APP/PS1 mice with forebrain neuron-specific FT knockout, followed by a battery of behavioral assessments, biochemical assays, and unbiased transcriptomic analysis. Our results showed that the neuronal FT deletion mitigates memory impairment and amyloid neuropathology in APP/PS1 mice through suppressing amyloid generation and reversing the pathogenic hyperactivation of mTORC1 signaling. These findings suggest that aberrant upregulation of protein farnesylation is an early driving force in the pathogenic cascade of AD and that targeting FT or its downstream signaling pathways presents a viable therapeutic strategy against AD.
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