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Kober DL, Stuchell-Brereton MD, Kluender CE, Dean HB, Strickland MR, Steinberg DF, Nelson SS, Baban B, Holtzman DM, Frieden C, Alexander-Brett J, Roberson ED, Song Y, Brett TJ. Functional insights from biophysical study of TREM2 interactions with apoE and Aβ 1-42. Alzheimers Dement 2020; 17:10.1002/alz.12194. [PMID: 33090700 PMCID: PMC8026773 DOI: 10.1002/alz.12194] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 08/12/2020] [Accepted: 08/20/2020] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Triggering receptor expressed on myeloid cells-2 (TREM2) is an immune receptor expressed on microglia that also can become soluble (sTREM2). How TREM2 engages different ligands remains poorly understood. METHODS We used comprehensive biolayer interferometry (BLI) analysis to investigate TREM2 and sTREM2 interactions with apolipoprotein E (apoE) and monomeric amyloid beta (Aβ) (mAβ42). RESULTS TREM2 engagement of apoE was protein mediated with little effect of lipidation, showing slight affinity differences between isoforms (E4 > E3 > E2). Another family member, TREML2, did not bind apoE. Disease-linked TREM2 variants within a "basic patch" minimally impact apoE binding. Instead, TREM2 uses a unique hydrophobic surface to bind apoE, which requires the apoE hinge region. TREM2 and sTREM2 directly bind mAβ42 and potently inhibit Aβ42 polymerization, suggesting a potential role for soluble sTREM2 in preventing AD pathogenesis. DISCUSSION These findings demonstrate that TREM2 has at least two ligand-binding surfaces that might be therapeutic targets and uncovers a potential function for sTREM2 in directly inhibiting Aβ polymerization.
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Affiliation(s)
- Daniel L. Kober
- Molecular Microbiology and Microbial Pathogenesis Program, Washington University School of Medicine, St. Louis, Missouri 63110
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Melissa D. Stuchell-Brereton
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Colin E. Kluender
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
- Biochemistry, Biophysics, and Structural Biology Program, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Hunter B. Dean
- Center for Neurodegeneration and Experimental Therapeutics, Alzheimer’s Disease Center, Departments of Neurology and Neurobiology, University of Alabama at Birmingham, AL 35294
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL 35294
| | - Michael R. Strickland
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Deborah F. Steinberg
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Samantha S. Nelson
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Berevan Baban
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - David M. Holtzman
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110
- Charles F. and Joanne Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Carl Frieden
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jennifer Alexander-Brett
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Erik D. Roberson
- Center for Neurodegeneration and Experimental Therapeutics, Alzheimer’s Disease Center, Departments of Neurology and Neurobiology, University of Alabama at Birmingham, AL 35294
| | - Yuhua Song
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL 35294
| | - Tom J. Brett
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110
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202
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Cignarella F, Filipello F, Bollman B, Cantoni C, Locca A, Mikesell R, Manis M, Ibrahim A, Deng L, Benitez BA, Cruchaga C, Licastro D, Mihindukulasuriya K, Harari O, Buckland M, Holtzman DM, Rosenthal A, Schwabe T, Tassi I, Piccio L. TREM2 activation on microglia promotes myelin debris clearance and remyelination in a model of multiple sclerosis. Acta Neuropathol 2020; 140:513-534. [PMID: 32772264 PMCID: PMC7498497 DOI: 10.1007/s00401-020-02193-z] [Citation(s) in RCA: 196] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 01/13/2023]
Abstract
Multiple sclerosis (MS) is an inflammatory, demyelinating, and neurodegenerative disease of the central nervous system (CNS) triggered by autoimmune mechanisms. Microglia are critical for the clearance of myelin debris in areas of demyelination, a key step to allow remyelination. TREM2 is expressed by microglia and promotes microglial survival, proliferation, and phagocytic activity. Herein we demonstrate that TREM2 was highly expressed on myelin-laden phagocytes in active demyelinating lesions in the CNS of subjects with MS. In gene expression studies, macrophages from subjects with TREM2 genetic deficiency displayed a defect in phagocytic pathways. Treatment with a new TREM2 agonistic antibody promoted the clearance of myelin debris in the cuprizone model of CNS demyelination. Effects included enhancement of myelin uptake and degradation, resulting in accelerated myelin debris removal by microglia. Most importantly, antibody-dependent TREM2 activation on microglia increased density of oligodendrocyte precursors in areas of demyelination, as well as the formation of mature oligodendrocytes thus enhancing remyelination and axonal integrity. These results are relevant as they propose TREM2 on microglia as a potential new target to promote remyelination.
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Affiliation(s)
- Francesca Cignarella
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
- Alector, 131 Oyster Point Blvd #600, South San Francisco, CA, 94080, USA
| | - Fabia Filipello
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, Pieve Emanuele - Milan, 20090, Italy
| | - Bryan Bollman
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
| | - Claudia Cantoni
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
| | - Alberto Locca
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
| | - Robert Mikesell
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
| | - Melissa Manis
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
| | - Adiljan Ibrahim
- Alector, 131 Oyster Point Blvd #600, South San Francisco, CA, 94080, USA
| | - Li Deng
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
- Department of Anesthesiology, First Affiliated Hospital of Soochow University, Suzhou, 215006, Jiangsu, China
| | - Bruno A Benitez
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Carlos Cruchaga
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Danilo Licastro
- ARGO Open Lab Platform for Genome sequencing, AREA Science Park, Padriciano 99, 34149, Trieste, Italy
| | - Kathie Mihindukulasuriya
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Oscar Harari
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Michael Buckland
- Brain and Mind Centre, University of Sydney, 94 Mallett St Camperdown, Sydney, NSW, 2050, Australia
| | - David M Holtzman
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Arnon Rosenthal
- Alector, 131 Oyster Point Blvd #600, South San Francisco, CA, 94080, USA
| | - Tina Schwabe
- Alector, 131 Oyster Point Blvd #600, South San Francisco, CA, 94080, USA
| | - Ilaria Tassi
- Alector, 131 Oyster Point Blvd #600, South San Francisco, CA, 94080, USA.
| | - Laura Piccio
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA.
- NeuroGenomics and Informatics, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Brain and Mind Centre, University of Sydney, 94 Mallett St Camperdown, Sydney, NSW, 2050, Australia.
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203
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Korvatska O, Kiianitsa K, Ratushny A, Matsushita M, Beeman N, Chien WM, Satoh JI, Dorschner MO, Keene CD, Bammler TK, Bird TD, Raskind WH. Triggering Receptor Expressed on Myeloid Cell 2 R47H Exacerbates Immune Response in Alzheimer's Disease Brain. Front Immunol 2020; 11:559342. [PMID: 33101276 PMCID: PMC7546799 DOI: 10.3389/fimmu.2020.559342] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/25/2020] [Indexed: 01/11/2023] Open
Abstract
The R47H variant in the microglial triggering receptor expressed on myeloid cell 2 (TREM2) receptor is a strong risk factor for Alzheimer’s disease (AD). To characterize processes affected by R47H, we performed an integrative network analysis of genes expressed in brains of AD patients with R47H, sporadic AD without the variant, and patients with polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), systemic disease with early-onset dementia caused by loss-of-function mutations in TREM2 or its adaptor TYRO protein tyrosine kinase-binding protein (TYROBP). Although sporadic AD had few perturbed microglial and immune genes, TREM2 R47H AD demonstrated upregulation of interferon type I response and pro-inflammatory cytokines accompanied by induction of NKG2D stress ligands. In contrast, PLOSL had distinct sets of highly perturbed immune and microglial genes that included inflammatory mediators, immune signaling, cell adhesion, and phagocytosis. TREM2 knockout (KO) in THP1, a human myeloid cell line that constitutively expresses the TREM2- TYROBP receptor, inhibited response to the viral RNA mimetic poly(I:C) and phagocytosis of amyloid-beta oligomers; overexpression of ectopic TREM2 restored these functions. Compared with wild-type protein, R47H TREM2 had a higher stimulatory effect on the interferon type I response signature. Our findings point to a role of the TREM2 receptor in the control of the interferon type I response in myeloid cells and provide insight regarding the contribution of R47H TREM2 to AD pathology.
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Affiliation(s)
- Olena Korvatska
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, Seattle, WA, United States
| | - Alexander Ratushny
- Seattle Biomedical Research Institute and Institute for Systems Biology, Seattle, WA, United States
| | - Mark Matsushita
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
| | - Neal Beeman
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
| | - Wei-Ming Chien
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
| | - Jun-Ichi Satoh
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Tokyo, Japan
| | - Michael O Dorschner
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - Theo K Bammler
- Department of Environmental and Occupational Health Sciences, Seattle, WA, United States
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, WA, United States.,Geriatric Research, Education and Clinical Center, Veteran Affairs Puget Sound Health Care System, Seattle, WA, United States
| | - Wendy H Raskind
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States.,Geriatric Research, Education and Clinical Center, Veteran Affairs Puget Sound Health Care System, Seattle, WA, United States.,Mental Illness Research, Education and Clinical Center, Department of Veteran Affairs, Seattle, WA, United States
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204
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Paouri E, Georgopoulos S. Systemic and CNS Inflammation Crosstalk: Implications for Alzheimer's Disease. Curr Alzheimer Res 2020; 16:559-574. [PMID: 30907316 DOI: 10.2174/1567205016666190321154618] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 02/26/2019] [Accepted: 03/19/2019] [Indexed: 12/14/2022]
Abstract
After years of failed therapeutic attempts targeting beta-amyloid (Aβ) in AD, there is now increasing evidence suggesting that inflammation holds a pivotal role in AD pathogenesis and immune pathways can possibly comprise primary therapeutic targets. Inflammation is a key characteristic of numerous diseases including neurodegenerative disorders and thus not surprisingly suppression of inflammation frequently constitutes a major therapeutic strategy for a wide spectrum of disorders. Several brain-resident and peripherally-derived immune populations and inflammatory mediators are involved in AD pathophysiology, with microglia comprising central cellular player in the disease process. Systemic inflammation, mostly in the form of infections, has long been observed to induce behavioral alterations and cognitive dysfunction, suggesting for a close interaction of the peripheral immune system with the brain. Systemic inflammation can result in neuroinflammation, mainly exhibited as microglial activation, production of inflammatory molecules, as well as recruitment of peripheral immune cells in the brain, thus shaping a cerebral inflammatory milieu that may seriously impact neuronal function. Increasing clinical and experimental studies have provided significant evidence that acute (e.g. infections) or chronic (e.g. autoimmune diseases like rheumatoid arthritis) systemic inflammatory conditions may be associated with increased AD risk and accelerate AD progression. Here we review the current literature that links systemic with CNS inflammation and the implications of this interaction for AD in the context of acute and chronic systemic pathologies as acute infection and rheumatoid arthritis. Elucidating the mechanisms that govern the crosstalk between the peripheral and the local brain immune system may provide the ground for new therapeutic approaches that target the immune-brain interface and shed light on the understanding of AD.
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Affiliation(s)
- Evi Paouri
- Laboratory of Cellular Neurobiology, Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Spiros Georgopoulos
- Laboratory of Cellular Neurobiology, Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
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205
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Kim E, Otgontenger U, Jamsranjav A, Kim SS. Deleterious Alteration of Glia in the Brain of Alzheimer's Disease. Int J Mol Sci 2020; 21:ijms21186676. [PMID: 32932623 PMCID: PMC7555758 DOI: 10.3390/ijms21186676] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 02/07/2023] Open
Abstract
The deterioration of neurons in Alzheimer’s disease (AD) arises from genetic, immunologic, and cellular factors inside the cortex. The traditional consensus of the amyloid-beta (Aβ) paradigm as a singular cause of AD has been under revision, with the accumulation of exploding neurobiological evidence. Among the multifaceted casualties of AD, the involvement of glia gains significance for its dynamic contribution to neurons, either in a neuroprotective or neurotoxic fashion. Basically, microglia and astrocytes contribute to neuronal sustainability by releasing neuroprotective cytokines, maintaining an adequate amount of glutamate in the synapse, and pruning excessive synaptic terminals. Such beneficial effects divert to the other detrimental cascade in chronic neuroinflammatory conditions. In this change, there are new discoveries of specific cytokines, microRNAs, and complementary factors. Previously unknown mechanisms of ion channels such as Kv1.3, Kir2.1, and HCN are also elucidated in the activation of microglia. The activation of glia is responsible for the excitotoxicity through the overflow of glutamate transmitter via mGluRs expressed on the membrane, which can lead to synaptic malfunction and engulfment. The communication between microglia and astrocytes is mediated through exosomes as well as cytokines, where numerous pieces of genetic information are transferred in the form of microRNAs. The new findings tell us that the neuronal environment in the AD condition is a far more complicated and dynamically interacting space. The identification of each molecule in the milieu and cellular communication would contribute to a better understanding of AD in the neurobiological perspective, consequently suggesting a possible therapeutic clue.
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Affiliation(s)
| | | | | | - Sang Seong Kim
- Correspondence: ; Tel.: +82-31-400-5812; Fax: +82-31-400-5958
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206
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Raha-Chowdhury R, Henderson JW, Raha AA, Vuono R, Bickerton A, Jones E, Fincham R, Allinson K, Holland A, Zaman SH. Choroid Plexus Acts as Gatekeeper for TREM2, Abnormal Accumulation of ApoE, and Fibrillary Tau in Alzheimer's Disease and in Down Syndrome Dementia. J Alzheimers Dis 2020; 69:91-109. [PMID: 30909239 PMCID: PMC6598012 DOI: 10.3233/jad-181179] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: Genetic factors that influence Alzheimer’s disease (AD) risk include mutations in TREM2 and allelic variants of Apolipoprotein E, influencing AD pathology in the general population and in Down syndrome (DS). Evidence shows that dysfunction of the choroid plexus may compromise the blood-cerebrospinal fluid (CSF) barrier, altering secretary, transport and immune function that can affect AD pathology. Objective: To investigate the genotype and phenotype of DS individuals in relation to choroid plexus damage and blood-CSF barrier leakage to identify markers that could facilitate early diagnosis of AD in DS. Methods: To assess allele frequency and haplotype associations ApoE, Tau, TREM2, and HLA-DR were analyzed by SNP analysis in DS participants (n = 47) and controls (n = 50). The corresponding plasma protein levels were measured by ELISA. Postmortem brains from DS, AD, and age-matched controls were analyzed by immunohistochemistry. Results: Haplotype analysis showed that individuals with Tau H1/H1 and ApoEɛ4 genotypes were more prevalent among DS participants with an earlier diagnosis of dementia (17%) compared to H1/H2 haplotypes (6%). Plasma TREM2 levels decreased whereas phospho-tau levels increased with age in DS. In AD and DS brain, insoluble tau and ApoE were found to accumulate in the choroid plexus. Conclusion: Accumulation of tau and ApoE in the choroid plexus may increase the oligomerization rate of Aβ42 and impair tau trafficking, leading to AD pathology. We have identified a high-risk haplotype: ApoEɛ4, Tau/H1, and TREM2/T, that manifests age-related changes potentially opening a window for treatment many years prior to the manifestation of the AD dementia.
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Affiliation(s)
- Ruma Raha-Chowdhury
- Cambridge Intellectual and Developmental Disabilities Research Group, Department of Psychiatry, Cambridge, UK.,John van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - James W Henderson
- John van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Animesh Alexander Raha
- John van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Romina Vuono
- John van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Anastasia Bickerton
- Cambridge Intellectual and Developmental Disabilities Research Group, Department of Psychiatry, Cambridge, UK
| | - Elizabeth Jones
- Cambridge Intellectual and Developmental Disabilities Research Group, Department of Psychiatry, Cambridge, UK
| | - Robert Fincham
- Clinical Pathology, Addenbrookes Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Kieren Allinson
- Clinical Pathology, Addenbrookes Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Anthony Holland
- Cambridge Intellectual and Developmental Disabilities Research Group, Department of Psychiatry, Cambridge, UK
| | - Shahid H Zaman
- Cambridge Intellectual and Developmental Disabilities Research Group, Department of Psychiatry, Cambridge, UK.,Cambridgeshire and Peterborough Foundation NHS Trust, Cambridge, UK
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207
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Ennerfelt HE, Lukens JR. The role of innate immunity in Alzheimer's disease. Immunol Rev 2020; 297:225-246. [PMID: 32588460 PMCID: PMC7783860 DOI: 10.1111/imr.12896] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 12/12/2022]
Abstract
The amyloid hypothesis has dominated Alzheimer's disease (AD) research for almost 30 years. This hypothesis hinges on the predominant clinical role of the amyloid beta (Aβ) peptide in propagating neurofibrillary tangles (NFTs) and eventual cognitive impairment in AD. Recent research in the AD field has identified the brain-resident macrophages, known as microglia, and their receptors as integral regulators of both the initiation and propagation of inflammation, Aβ accumulation, neuronal loss, and memory decline in AD. Emerging studies have also begun to reveal critical roles for distinct innate immune pathways in AD pathogenesis, which has led to great interest in harnessing the innate immune response as a therapeutic strategy to treat AD. In this review, we will highlight recent advancements in our understanding of innate immunity and inflammation in AD onset and progression. Additionally, there has been mounting evidence suggesting pivotal contributions of environmental factors and lifestyle choices in AD pathogenesis. Therefore, we will also discuss recent findings, suggesting that many of these AD risk factors influence AD progression via modulation of microglia and immune responses.
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Affiliation(s)
- Hannah E. Ennerfelt
- Center for Brain Immunology and Glia (BIG), Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
- Cell and Molecular Biology Training Program, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - John R. Lukens
- Center for Brain Immunology and Glia (BIG), Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
- Cell and Molecular Biology Training Program, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
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208
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Price BR, Sudduth TL, Weekman EM, Johnson S, Hawthorne D, Woolums A, Wilcock DM. Therapeutic Trem2 activation ameliorates amyloid-beta deposition and improves cognition in the 5XFAD model of amyloid deposition. J Neuroinflammation 2020; 17:238. [PMID: 32795308 PMCID: PMC7427742 DOI: 10.1186/s12974-020-01915-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/30/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Triggering receptor expressed on myeloid cell-2 (TREM2) is a lipid and lipoprotein binding receptor expressed by cells of myeloid origin. Homozygous TREM2 mutations cause early onset progressive presenile dementia while heterozygous, point mutations triple the risk of Alzheimer's disease (AD). Although human genetic findings support the notion that loss of TREM2 function exacerbates neurodegeneration, it is not clear whether activation of TREM2 in a disease state would result in therapeutic benefits. To determine the viability of TREM2 activation as a therapeutic strategy, we sought to characterize an agonistic Trem2 antibody (AL002a) and test its efficacy and mechanism of action in an aggressive mouse model of amyloid deposition. METHODS To determine whether agonism of Trem2 results in therapeutic benefits, we designed both intracranial and systemic administration studies. 5XFAD mice in the intracranial administration study were assigned to one of two injection groups: AL002a, a Trem2-agonizing antibody, or MOPC, an isotype-matched control antibody. Mice were then subject to a single bilateral intracranial injection into the frontal cortex and hippocampus and euthanized 72 h later. The tissue from the left hemisphere was histologically examined for amyloid-beta and microglia activation, whereas the tissue from the right hemisphere was used for biochemical analyses. Similarly, mice in the systemic administration study were randomized to one of the aforementioned injection groups and the assigned antibody was administered intraperitoneally once a week for 14 weeks. Mice underwent behavioral assessment between the 12- and 14-week timepoints and were euthanized 24 h after their final injection. The tissue from the left hemisphere was used for histological analyses whereas the tissue from the right hemisphere was used for biochemical analyses. RESULTS Here, we show that chronic activation of Trem2, in the 5XFAD mouse model of amyloid deposition, leads to reversal of the amyloid-associated gene expression signature, recruitment of microglia to plaques, decreased amyloid deposition, and improvement in spatial learning and novel object recognition memory. CONCLUSIONS These findings indicate that Trem2 activators may be effective for the treatment of AD and possibly other neurodegenerative disorders.
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Affiliation(s)
- Brittani R Price
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Tiffany L Sudduth
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Erica M Weekman
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Sherika Johnson
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Danielle Hawthorne
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Abigail Woolums
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA.
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA.
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209
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TMEM59 interacts with TREM2 and modulates TREM2-dependent microglial activities. Cell Death Dis 2020; 11:678. [PMID: 32826884 PMCID: PMC7442838 DOI: 10.1038/s41419-020-02874-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 08/01/2020] [Accepted: 08/03/2020] [Indexed: 12/20/2022]
Abstract
The surface receptor triggering receptor expressed on myeloid cells 2 (TREM2) plays a crucial role in maintaining a multitude of microglial activities, such as survival, proliferation, migration, metabolism, inflammation, and phagocytosis. However, the molecular mechanisms underlying TREM2-mediated microglial activities remain largely elusive. Herein, we found that TREM2 interacted with the type I transmembrane protein TMEM59, whose expression could facilitate autophagic flux through its carboxyl-terminus. TMEM59 expression was decreased upon lipopolysaccharide treatment. While downregulation of TMEM59 promoted anti-inflammatory factor expression and attenuated lipopolysaccharide treatment-induced inflammation. Importantly, we found that overexpression of TREM2 reduced TMEM59 protein levels through promoting its degradation, whereas TMEM59 levels were elevated in Trem2-deficient microglia. Finally, impaired survival, proliferation, migration, and phagocytosis, as well as dysregulated autophagy and metabolism in Trem2-deficient microglia were attenuated upon TMEM59 silencing. Together, our findings reveal a novel function of TREM2 in mediating TMEM59 protein degradation and demonstrate the importance of TMEM59 homeostasis in maintaining TREM2-mediated microglial activities.
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210
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Fitz NF, Wolfe CM, Playso BE, Biedrzycki RJ, Lu Y, Nam KN, Lefterov I, Koldamova R. Trem2 deficiency differentially affects phenotype and transcriptome of human APOE3 and APOE4 mice. Mol Neurodegener 2020; 15:41. [PMID: 32703241 PMCID: PMC7379780 DOI: 10.1186/s13024-020-00394-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/16/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Alzheimer's Disease (AD) is a neurodegenerative disorder influenced by aging and genetic risk factors. The inheritance of APOEε4 and variants of Triggering Receptor Expressed on Myeloid cells 2 (TREM2) are major genetic risk factors for AD. Recent studies showed that APOE binds to TREM2, thus raising the possibility of an APOE-TREM2 interaction that can modulate AD pathology. METHODS The aim of this study was to investigate this interaction using complex AD model mice - a crossbreed of Trem2ko and APP/PSEN1dE9 mice expressing human APOE3 or APOE4 isoforms (APP/E3 and APP/E4 respectively), and their WT littermates (E3 and E4), and evaluate cognition, steady-state amyloid load, plaque compaction, plaque growth rate, glial response, and brain transcriptome. RESULTS In both, APP/E3 and APP/E4 mice, Trem2 deletion reduced plaque compaction but did not significantly affect steady-state plaque load. Importantly, the lack of TREM2 increased plaque growth that negatively correlated to the diminished microglia barrier, an effect most pronounced at earlier stages of amyloid deposition. We also found that Trem2 deficiency significantly decreased plaque-associated APOE protein in APP/E4 but not in APP/E3 mice in agreement with RNA-seq data. Interestingly, we observed a significant decrease of Apoe mRNA expression in plaque-associated microglia of APP/E4/Trem2ko vs APP/E4 mice. The absence of TREM2, worsened cognitive performance in APP transgenic mice but not their WT littermates. Gene expression analysis identified Trem2 signature - a cluster of highly connected immune response genes, commonly downregulated as a result of Trem2 deletion in all genotypes including APP and WT littermates. Furthermore, we identified sets of genes that were affected in TREM2- and APOE isoform-dependent manner. Among them were Clec7a and Csf1r upregulated in APP/E4 vs APP/E3 mice, a result further validated by in situ hybridization analysis. In contrast, Tyrobp and several genes involved in the C1Q complement cascade had a higher expression level in APP/E3 versus their APP/E4 counterparts. CONCLUSIONS Our data demonstrate that lack of Trem2 differentially impacts the phenotype and brain transcriptome of APP mice expressing human APOE isoforms. The changes probably reflect the different effect of APOE isoforms on amyloid deposition.
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Affiliation(s)
- Nicholas F. Fitz
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Cody M. Wolfe
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Brittany E. Playso
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Richard J. Biedrzycki
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Yi Lu
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Kyong Nyon Nam
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Iliya Lefterov
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Radosveta Koldamova
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
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211
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Peripheral TREM2 mRNA levels in early and late-onset Alzheimer disease's patients. Mol Biol Rep 2020; 47:5903-5909. [PMID: 32681391 DOI: 10.1007/s11033-020-05661-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/08/2020] [Indexed: 01/09/2023]
Abstract
'Triggering receptor expressed on myeloid cells 2' (TREM2) gene is involved in Alzheimer's disease (AD) and TREM2 mRNA expression is known to be increased in the peripheral blood cells of AD patients. In this study, we examined the expression levels of TREM2 mRNA in peripheral leukocytes of early and late-onset AD patients. We have also investigated the effect of the presence of APOE ε4 allele on TREM2 expression. TREM2 mRNA expression was analyzed in 30 early-onset AD (EOAD) patients, 38 late-onset AD (LOAD) patients, and in their age-matched controls by using quantitative real-time polymerase chain reaction. TREM2 levels in LOAD patients were higher than EOAD. Also, in elderly controls significantly higher TREM2 levels were found compared with young controls. Moreover, APOE ε4 carriers in LOAD patients exhibited significantly higher TREM2 expression levels than APOE ε4 non-carriers and elderly controls. Also, correlation analysis showed that TREM2 mRNA expression was increased by age. The differential expression of TREM2 mRNA levels between EOAD and LOAD patients might be independent of the AD disease status and results from an age-related increase in TREM2 expression. In LOAD patients, increased age and the presence of APOE ε4 allele further increase TREM2 expression. Taken together, we can suggest that age is a factor that increases TREM2 expression, and TREM2 and APOE ε4 may interact together in the pathogenesis of LOAD.
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212
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Rodríguez-Gómez JA, Kavanagh E, Engskog-Vlachos P, Engskog MK, Herrera AJ, Espinosa-Oliva AM, Joseph B, Hajji N, Venero JL, Burguillos MA. Microglia: Agents of the CNS Pro-Inflammatory Response. Cells 2020; 9:E1717. [PMID: 32709045 PMCID: PMC7407646 DOI: 10.3390/cells9071717] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/21/2022] Open
Abstract
The pro-inflammatory immune response driven by microglia is a key contributor to the pathogenesis of several neurodegenerative diseases. Though the research of microglia spans over a century, the last two decades have increased our understanding exponentially. Here, we discuss the phenotypic transformation from homeostatic microglia towards reactive microglia, initiated by specific ligand binding to pattern recognition receptors including toll-like receptor-4 (TLR4) or triggering receptors expressed on myeloid cells-2 (TREM2), as well as pro-inflammatory signaling pathways triggered such as the caspase-mediated immune response. Additionally, new research disciplines such as epigenetics and immunometabolism have provided us with a more holistic view of how changes in DNA methylation, microRNAs, and the metabolome may influence the pro-inflammatory response. This review aimed to discuss our current knowledge of pro-inflammatory microglia from different angles, including recent research highlights such as the role of exosomes in spreading neuroinflammation and emerging techniques in microglia research including positron emission tomography (PET) scanning and the use of human microglia generated from induced pluripotent stem cells (iPSCs). Finally, we also discuss current thoughts on the impact of pro-inflammatory microglia in neurodegenerative diseases.
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Affiliation(s)
- José A. Rodríguez-Gómez
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Medical Physiology and Biophysics, Faculty of Medicine, University of Seville, 41009 Sevilla, Spain
| | - Edel Kavanagh
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Pinelopi Engskog-Vlachos
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institute, 17177 Stockholm, Sweden; (P.E.-V.); (B.J.)
| | - Mikael K.R. Engskog
- Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry, Uppsala University, 751 23 Uppsala, Sweden;
| | - Antonio J. Herrera
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Ana M. Espinosa-Oliva
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Bertrand Joseph
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institute, 17177 Stockholm, Sweden; (P.E.-V.); (B.J.)
| | - Nabil Hajji
- Division of Brain Sciences, The John Fulcher Molecular Neuro-Oncology Laboratory, Imperial College London, London W12 ONN, UK;
| | - José L. Venero
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Miguel A. Burguillos
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
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213
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Villa C, Lavitrano M, Salvatore E, Combi R. Molecular and Imaging Biomarkers in Alzheimer's Disease: A Focus on Recent Insights. J Pers Med 2020; 10:jpm10030061. [PMID: 32664352 PMCID: PMC7565667 DOI: 10.3390/jpm10030061] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/28/2020] [Accepted: 07/07/2020] [Indexed: 12/15/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common neurodegenerative disease among the elderly, affecting millions of people worldwide and clinically characterized by a progressive and irreversible cognitive decline. The rapid increase in the incidence of AD highlights the need for an easy, efficient and accurate diagnosis of the disease in its initial stages in order to halt or delay the progression. The currently used diagnostic methods rely on measures of amyloid-β (Aβ), phosphorylated (p-tau) and total tau (t-tau) protein levels in the cerebrospinal fluid (CSF) aided by advanced neuroimaging techniques like positron emission tomography (PET) and magnetic resonance imaging (MRI). However, the invasiveness of these procedures and the high cost restrict their utilization. Hence, biomarkers from biological fluids obtained using non-invasive methods and novel neuroimaging approaches provide an attractive alternative for the early diagnosis of AD. Such biomarkers may also be helpful for better understanding of the molecular mechanisms underlying the disease, allowing differential diagnosis or at least prolonging the pre-symptomatic stage in patients suffering from AD. Herein, we discuss the advantages and limits of the conventional biomarkers as well as recent promising candidates from alternative body fluids and new imaging techniques.
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Affiliation(s)
- Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
- Correspondence: (C.V.); (R.C.)
| | - Marialuisa Lavitrano
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
- Institute for the Experimental Endocrinology and Oncology, National Research Council (IEOS-CNR), 80131 Naples, Italy;
| | - Elena Salvatore
- Department of Neurosciences and Reproductive and Odontostomatological Sciences, Federico II University, 80131 Naples, Italy;
| | - Romina Combi
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
- Correspondence: (C.V.); (R.C.)
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214
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Yang J, Fu Z, Zhang X, Xiong M, Meng L, Zhang Z. TREM2 ectodomain and its soluble form in Alzheimer's disease. J Neuroinflammation 2020; 17:204. [PMID: 32635934 PMCID: PMC7341574 DOI: 10.1186/s12974-020-01878-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 06/23/2020] [Indexed: 12/14/2022] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a receptor mainly expressed on the surface of microglia. It mediates multiple pathophysiological processes in various diseases. Recently, TREM2 has been found to play a role in the development of Alzheimer's disease (AD). TREM2 is a transmembrane protein that is specifically expressed on microglia in the brain. It contains a long ectodomain that directly interacts with the extracellular environment to regulate microglial function. The ectodomain of TREM2 is processed by a disintegrin and metalloprotease, resulting in the release of a soluble form of TREM2 (sTREM2). Recent studies have demonstrated that sTREM2 is a bioactive molecule capable of binding ligands, activating microglia, and regulating immune responses during the AD continuum. Clinical studies revealed that sTREM2 level is elevated in cerebrospinal fluid (CSF) of AD patients, and the sTREM2 level is positively correlated with the levels of classical CSF biomarkers, namely t-tau and p-tau, indicating that it is a reliable predictor of the early stages of AD. Herein, we summarize the key results on the generation, structure, and function of sTREM2 to provide new insights into TREM2-related mechanisms underlying AD pathogenesis and to promote the development of TREM2-based therapeutic strategy.
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Affiliation(s)
- Jiaolong Yang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Zhihui Fu
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Xingyu Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Min Xiong
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Lanxia Meng
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
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215
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Liccardo D, Marzano F, Carraturo F, Guida M, Femminella GD, Bencivenga L, Agrimi J, Addonizio A, Melino I, Valletta A, Rengo C, Ferrara N, Rengo G, Cannavo A. Potential Bidirectional Relationship Between Periodontitis and Alzheimer's Disease. Front Physiol 2020; 11:683. [PMID: 32719612 PMCID: PMC7348667 DOI: 10.3389/fphys.2020.00683] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/26/2020] [Indexed: 12/15/2022] Open
Abstract
Alzheimer’s disease (AD) is the most prevalent form of dementia in the elderly population, representing a global public health priority. Despite a large improvement in understanding the pathogenesis of AD, the etiology of this disorder remains still unclear, and no current treatment is able to prevent, slow, or stop its progression. Thus, there is a keen interest in the identification and modification of the risk factors and novel molecular mechanisms associated with the development and progression of AD. In this context, it is worth noting that several findings support the existence of a direct link between neuronal and non-neuronal inflammation/infection and AD progression. Importantly, recent studies are now supporting the existence of a direct relationship between periodontitis, a chronic inflammatory oral disease, and AD. The mechanisms underlying the association remain to be fully elucidated, however, it is generally accepted, although not confirmed, that oral pathogens can penetrate the bloodstream, inducing a low-grade systemic inflammation that negatively affects brain function. Indeed, a recent report demonstrated that oral pathogens and their toxic proteins infect the brain of AD patients. For instance, when AD progresses from the early to the more advanced stages, patients could no longer be able to adequately adhere to proper oral hygiene practices, thus leading to oral dysbiosis that, in turn, fuels infection, such as periodontitis. Therefore, in this review, we will provide an update on the emerging (preclinical and clinical) evidence that supports the relationship existing between periodontitis and AD. More in detail, we will discuss data attesting that periodontitis and AD share common risk factors and a similar hyper-inflammatory phenotype.
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Affiliation(s)
- Daniela Liccardo
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.,Center for Translational Medicine, Temple University, Philadelphia, PA, United States
| | - Federica Marzano
- Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy
| | | | - Marco Guida
- Department of Biology, University of Naples Federico II, Naples, Italy
| | | | - Leonardo Bencivenga
- Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy
| | - Jacopo Agrimi
- Division of Cardiology, Johns Hopkins University, Baltimore, MD, United States
| | - Armida Addonizio
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy
| | - Imma Melino
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy
| | - Alessandra Valletta
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy
| | - Carlo Rengo
- Department of Prosthodontics and Dental Materials, School of Dental Medicine, University of Siena, Siena, Italy
| | - Nicola Ferrara
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.,Istituti Clinici Scientifici ICS Maugeri - S.p.A.-Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Scientifico di Telese Terme, Telese, Italy
| | - Giuseppe Rengo
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.,Istituti Clinici Scientifici ICS Maugeri - S.p.A.-Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Scientifico di Telese Terme, Telese, Italy
| | - Alessandro Cannavo
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Naples, Italy
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216
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Gray SC, Kinghorn KJ, Woodling NS. Shifting equilibriums in Alzheimer's disease: the complex roles of microglia in neuroinflammation, neuronal survival and neurogenesis. Neural Regen Res 2020; 15:1208-1219. [PMID: 31960800 PMCID: PMC7047786 DOI: 10.4103/1673-5374.272571] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 09/02/2019] [Accepted: 10/22/2019] [Indexed: 12/13/2022] Open
Abstract
Alzheimer's disease is the leading cause of dementia. Its increased prevalence in developed countries, due to the sharp rise in ageing populations, presents one of the costliest challenges to modern medicine. In order to find disease-modifying therapies to confront this challenge, a more complete understanding of the pathogenesis of Alzheimer's disease is necessary. Recent studies have revealed increasing evidence for the roles played by microglia, the resident innate immune system cells of the brain. Reflecting the well-established roles of microglia in reacting to pathogens and inflammatory stimuli, there is now a growing literature describing both protective and detrimental effects for individual cytokines and chemokines produced by microglia in Alzheimer's disease. A smaller but increasing number of studies have also addressed the divergent roles played by microglial neurotrophic and neurogenic factors, and how their perturbation may play a key role in the pathogenesis of Alzheimer's disease. Here we review recent findings on the roles played by microglia in neuroinflammation, neuronal survival and neurogenesis in Alzheimer's disease. In each case, landmark studies have provided evidence for the divergent ways in which microglia can either promote neuronal function and survival, or perturb neuronal function, leading to cell death. In many cases, the secreted molecules of microglia can lead to divergent effects depending on the magnitude and context of microglial activation. This suggests that microglial functions must be maintained in a fine equilibrium, in order to support healthy neuronal function, and that the cellular microenvironment in the Alzheimer's disease brain disrupts this fine balance, leading to neurodegeneration. Thus, an understanding of microglial homeostasis, both in health and across the trajectory of the disease state, will improve our understanding of the pathogenic mechanisms underlying Alzheimer's disease, and will hopefully lead to the development of microglial-based therapeutic strategies to restore equilibrium in the Alzheimer's disease brain.
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Affiliation(s)
- Sophie C. Gray
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Kerri J. Kinghorn
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Nathaniel S. Woodling
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK
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217
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Yan X, Wang B, Hu Y, Wang S, Zhang X. Abnormal Mitochondrial Quality Control in Neurodegenerative Diseases. Front Cell Neurosci 2020; 14:138. [PMID: 32655368 PMCID: PMC7324542 DOI: 10.3389/fncel.2020.00138] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/22/2020] [Indexed: 12/12/2022] Open
Abstract
Neurodegenerative diseases, including Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis, are characterized by a progressive loss of selective neuron subtypes in the central nervous system (CNS). Although various factors account for the initiation and development of these diseases, accumulating evidence shows that impaired mitochondrial function is a prominent and common mechanism. Mitochondria play a critical role in neurons and are involved in energy production, cellular metabolism regulation, intracellular calcium homeostasis, immune responses, and cell fate. Thus, cells in the CNS heavily rely on mitochondrial integrity. Many aspects of mitochondrial dysfunction are manifested in neurodegenerative diseases, including aberrant mitochondrial quality control (mitoQC), mitochondrial-driven inflammation, and bioenergetic defects. Herein, we briefly summarize the molecular basis of mitoQC, including mitochondrial proteostasis, biogenesis, dynamics, and organelle degradation. We also focus on the research, to date, regarding aberrant mitoQC and mitochondrial-driven inflammation in several common neurodegenerative diseases. In addition, we outline novel therapeutic strategies that target aberrant mitoQC in neurodegenerative diseases.
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Affiliation(s)
- Xu Yan
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Biyao Wang
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Yue Hu
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Sijian Wang
- Center of Implant Dentistry, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Xinwen Zhang
- Center of Implant Dentistry, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
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218
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Yan X, Wang B, Hu Y, Wang S, Zhang X. Abnormal Mitochondrial Quality Control in Neurodegenerative Diseases. Front Cell Neurosci 2020; 14:138. [PMID: 32655368 DOI: 10.3389/fncel.2020.00138/xml/nlm] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/22/2020] [Indexed: 05/25/2023] Open
Abstract
Neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's, and amyotrophic lateral sclerosis, are characterized by a progressive loss of selective neuron subtypes in the central nervous system (CNS). Although various factors account for the initiation and development of these diseases, accumulating evidence shows that impaired mitochondrial function is a prominent and common mechanism. Mitochondria play a critical role in neurons and are involved in energy production, cellular metabolism regulation, intracellular calcium homeostasis, immune responses, and cell fate. Thus, cells in the CNS heavily rely on mitochondrial integrity. Many aspects of mitochondrial dysfunction are manifested in neurodegenerative diseases, including aberrant mitochondrial quality control (mitoQC), mitochondrial-driven inflammation, and bioenergetic defects. Herein, we briefly summarize the molecular basis of mitoQC, including mitochondrial proteostasis, biogenesis, dynamics, and organelle degradation. We also focus on the research, to date, regarding aberrant mitoQC and mitochondrial-driven inflammation in several common neurodegenerative diseases. In addition, we outline novel therapeutic strategies that target aberrant mitoQC in neurodegenerative diseases.
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Affiliation(s)
- Xu Yan
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Biyao Wang
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Yue Hu
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Sijian Wang
- Center of Implant Dentistry, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Xinwen Zhang
- Center of Implant Dentistry, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
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219
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Schwabe T, Srinivasan K, Rhinn H. Shifting paradigms: The central role of microglia in Alzheimer's disease. Neurobiol Dis 2020; 143:104962. [PMID: 32535152 DOI: 10.1016/j.nbd.2020.104962] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 05/01/2020] [Accepted: 06/10/2020] [Indexed: 12/31/2022] Open
Abstract
Recent human genetic studies have challenged long standing hypotheses about the chain of events in Alzheimer's disease (AD), as the identification of genetic risk factors in microglial genes supports a causative role for microglia in the disease. Parallel transcriptome and histology studies at the single-cell level revealed a rich palette of microglial states affected by disease status and genetic risk factors. Taken together, those findings support microglia dysfunction as a central mechanism in AD etiology and thus the therapeutic potential of modulating microglial activity for AD treatment. Here we review how human genetic studies discovered microglial AD risk genes, such as TREM2, CD33, MS4A and APOE, and how experimental studies are beginning to decipher the cellular functions of some of these genes. Our review also focuses on recent transcriptomic studies of human microglia from postmortem tissue to critically assess areas of similarity and dissimilarity between human and mouse models currently in use in order to better understand the biology of innate immunity in AD.
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220
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Chen S, Peng J, Sherchan P, Ma Y, Xiang S, Yan F, Zhao H, Jiang Y, Wang N, Zhang JH, Zhang H. TREM2 activation attenuates neuroinflammation and neuronal apoptosis via PI3K/Akt pathway after intracerebral hemorrhage in mice. J Neuroinflammation 2020; 17:168. [PMID: 32466767 PMCID: PMC7257134 DOI: 10.1186/s12974-020-01853-x] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 05/21/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Neuroinflammation is an important host defense response to secondary brain injury after intracerebral hemorrhage (ICH). Triggering receptor expressed on myeloid cells 2 (TREM2) confers strong neuroprotective effects by attenuating neuroinflammation in experimental ischemic stroke. Recent studies suggest that apolipoprotein E (apoE) is a novel, high-affinity ligand of TREM2. This study aimed to investigate the effects of TREM2 activation on neuroinflammation and neuronal apoptosis in a mouse model of ICH. METHODS Adult male CD1 mice (n = 216) were subjected to intrastriatal injection of bacterial collagenase. The TREM2 ligand, apoE-mimetic peptide COG1410 was administered intranasally at 1 h after ICH induction. To elucidate the underlying mechanism, TREM2 small interfering RNA (siRNA) and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 were administered intracerebroventricularly prior to COG1410 treatment. Neurobehavioral tests, brain water content, immunofluorescence, western blotting, and Fluoro-Jade C- and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed. RESULTS Endogenous TREM2 expression was increased and peaked at 24 h after ICH. TREM2 was expressed on microglia, astrocytes, and neurons. COG1410 improved both short-term and long-term neurological functions, reduced brain edema, inhibited microglia/macrophage activation and neutrophil infiltration, and suppressed neuronal apoptotic cell death in perihematomal areas after ICH. Knockdown of endogenous TREM2 by TREM2 siRNA aggravated neurological deficits and decreased the expression of TREM2 in naïve and ICH mice. COG1410 was associated with upregulation of TREM2, PI3K, phosphorylated-Akt, and Bcl-2 and downregulation of TNF-α, IL-1β, and Bax after ICH. The neuroprotective effects of COG1410 were abolished by both TREM2 siRNA and PI3K inhibitor LY294002. CONCLUSIONS Our finding demonstrated that TREM2 activation improved neurological functions and attenuated neuroinflammation and neuronal apoptosis after ICH, which was, at least in part, mediated by activation of PI3K/Akt signaling pathway. Therefore, activation of TREM2 may be a potential therapeutic strategy for the management of ICH patients.
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Affiliation(s)
- Shengpan Chen
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA
| | - Jianhua Peng
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China
| | - Prativa Sherchan
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA
| | - Yongjie Ma
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Sishi Xiang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Feng Yan
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Hao Zhao
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Yong Jiang
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China
- Laboratory of Neurological Diseases and Brain Functions, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Ning Wang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - John H Zhang
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA.
- Department of Neurosurgery, Loma Linda University Medical Center, Loma Linda, CA, 92354, USA.
| | - Hongqi Zhang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China.
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A Role of Low-Density Lipoprotein Receptor-Related Protein 4 (LRP4) in Astrocytic Aβ Clearance. J Neurosci 2020; 40:5347-5361. [PMID: 32457076 DOI: 10.1523/jneurosci.0250-20.2020] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/10/2020] [Accepted: 05/16/2020] [Indexed: 01/28/2023] Open
Abstract
Amyloid-β (Aβ) deposition occurs years before cognitive symptoms appear and is considered a cause of Alzheimer's disease (AD). The imbalance of Aβ production and clearance leads to Aβ accumulation and Aβ deposition. Increasing evidence indicates an important role of astrocytes, the most abundant cell type among glial cells in the brain, in Aβ clearance. We explored the role of low-density lipoprotein receptor-related protein 4 (LRP4), a member of the LDLR family, in AD pathology. We show that Lrp4 is specifically expressed in astrocytes and its levels in astrocytes were higher than those of Ldlr and Lrp1, both of which have been implicated in Aβ uptake. LRP4 was reduced in postmortem brain tissues of AD patients. Genetic deletion of the Lrp4 gene augmented Aβ plaques in 5xFAD male mice, an AD mouse model, and exacerbated the deficits in neurotransmission, synchrony between the hippocampus and PFC, and cognition. Mechanistically, LRP4 promotes Aβ uptake by astrocytes likely by interacting with ApoE. Together, our study demonstrates that astrocytic LRP4 plays an important role in Aβ pathology and cognitive function.SIGNIFICANCE STATEMENT This study investigates how astrocytes, a type of non-nerve cells in the brain, may contribute to Alzheimer's disease (AD) development. We demonstrate that the low-density lipoprotein receptor-related protein 4 (LRP4) is reduced in the brain of AD patients. Mimicking the reduced levels in an AD mouse model exacerbates cognitive impairment and increases amyloid aggregates that are known to damage the brain. We show that LRP4 could promote the clearance of amyloid protein by astrocytes. Our results reveal a previously unappreciated role of LRP4 in AD development.
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222
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González-Guevara E, Cárdenas G, Pérez-Severiano F, Martínez-Lazcano JC. Dysregulated Brain Cholesterol Metabolism Is Linked to Neuroinflammation in Huntington's Disease. Mov Disord 2020; 35:1113-1127. [PMID: 32410324 DOI: 10.1002/mds.28089] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/08/2020] [Accepted: 04/15/2020] [Indexed: 12/12/2022] Open
Abstract
Huntington's disease is an autosomal-dominant, neurodegenerative disorder caused by a CAG repeat expansion in exon-1 of the huntingtin gene. Alterations in cholesterol metabolism and distribution have been reported in Huntington's disease, including abnormal interactions between mutant huntingtin and sterol regulatory element-binding proteins, decreased levels of apolipoprotein E/cholesterol/low-density lipoprotein receptor complexes, and alterations in the synthesis of ATP-binding cassette transporter A1. Plasma levels of 24S-hydroxycholestrol, a key intermediary in cholesterol metabolism and a possible marker in neurodegenerative diseases, decreased proportionally to the degree of caudate nucleus atrophy. The interaction of mutant huntingtin with sterol regulatory element-binding proteins is of particular interest given that sterol regulatory element-binding proteins play a dual role: They take part in lipid and cholesterol metabolism, but also in the inflammatory response that induces immune cell migration as well as toxic effects, particularly in astrocytes. This work summarizes current evidence on the metabolic and immune implications of sterol regulatory element-binding protein dysregulation in Huntington's disease, highlighting the potential use of drugs that modulate these alterations. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Edith González-Guevara
- Laboratorio de Neurofarmacología Molecular y Nanotecnología, Instituto Nacional de Neurología y Neurocirugía "MVS", Mexico City, Mexico
| | - Graciela Cárdenas
- Departamento de Neurología y Enfermedades Neuro-Infecciosas, Instituto Nacional de Neurología y Neurocirugía "MVS", Mexico City, Mexico
| | - Francisca Pérez-Severiano
- Laboratorio de Neurofarmacología Molecular y Nanotecnología, Instituto Nacional de Neurología y Neurocirugía "MVS", Mexico City, Mexico
| | - Juan Carlos Martínez-Lazcano
- Laboratorio de Neurofarmacología Molecular y Nanotecnología, Instituto Nacional de Neurología y Neurocirugía "MVS", Mexico City, Mexico
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Kloske CM, Wilcock DM. The Important Interface Between Apolipoprotein E and Neuroinflammation in Alzheimer's Disease. Front Immunol 2020; 11:754. [PMID: 32425941 PMCID: PMC7203730 DOI: 10.3389/fimmu.2020.00754] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 04/02/2020] [Indexed: 12/13/2022] Open
Abstract
Alzheimer’s disease (AD) is the most prevalent form of neurodegenerative disease, currently affecting over 5 million Americans with projections expected to rise as the population ages. The hallmark pathologies of AD are Aβ plaques composed of aggregated beta-amyloid (Aβ), and tau tangles composed of hyperphosphorylated, aggregated tau. These pathologies are typically accompanied by an increase in neuroinflammation as an attempt to ameliorate the pathology. This idea has pushed the field toward focusing on mechanisms and the influence neuroinflammation has on disease progression. The vast majority of AD cases are sporadic and therefore, researchers investigate genetic risk factors that could lead to AD. Apolipoprotein E (ApoE) is the largest genetic risk factor for developing AD. ApoE has 3 isoforms-ApoE2, ApoE3, and ApoE4. ApoE4 constitutes an increased risk of AD, with one copy increasing the risk about 4-fold and two copies increasing the risk about 15-fold compared to those with the ApoE3 allele. ApoE4 has been shown to play a role in Aβ deposition, tau tangle formation, neuroinflammation and many subsequent pathways. However, while we know that ApoE4 plays a role in these pathways and virtually all aspects of AD, the exact mechanism of how ApoE4 impacts AD progression is murky at best and therefore the role ApoE4 plays in these pathways needs to be elucidated. This review aims to discuss the current literature regarding the pathways and mechanisms of ApoE4 in AD progression with a focus on its role in neuroinflammation.
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Affiliation(s)
- Courtney M Kloske
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
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224
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Loving BA, Bruce KD. Lipid and Lipoprotein Metabolism in Microglia. Front Physiol 2020; 11:393. [PMID: 32411016 PMCID: PMC7198855 DOI: 10.3389/fphys.2020.00393] [Citation(s) in RCA: 115] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/02/2020] [Indexed: 12/25/2022] Open
Abstract
Microglia, once viewed as static bystanders with limited homeostatic functions, are now considered key players in the development of neuroinflammatory and neurodegenerative diseases. Microglial activation is a salient feature of neuroinflammation involving a dynamic process that generates multitudinous microglial phenotypes that can respond to a variety of situational cues in the central nervous system. Recently, a flurry of single cell RNA-sequencing studies have defined microglial phenotypes in unprecedented detail, and have highlighted robust changes in the expression of genes involved in lipid and lipoprotein metabolism. Increased expression of genes such as Apolipoprotein E (ApoE), Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) and Lipoprotein Lipase (LPL) in microglia during development, damage, and disease, suggest that increased lipid metabolism is needed to fuel protective cellular functions such as phagocytosis. This review describes our current understanding of lipid and lipoprotein metabolism in microglia, and highlights microglial lipid metabolism as a modifiable target for the treatment of neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis.
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Affiliation(s)
- Bailey A. Loving
- School of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States
| | - Kimberley D. Bruce
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States
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225
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Götzl JK, Brendel M, Werner G, Parhizkar S, Sebastian Monasor L, Kleinberger G, Colombo AV, Deussing M, Wagner M, Winkelmann J, Diehl-Schmid J, Levin J, Fellerer K, Reifschneider A, Bultmann S, Bartenstein P, Rominger A, Tahirovic S, Smith ST, Madore C, Butovsky O, Capell A, Haass C. Opposite microglial activation stages upon loss of PGRN or TREM2 result in reduced cerebral glucose metabolism. EMBO Mol Med 2020; 11:emmm.201809711. [PMID: 31122931 PMCID: PMC6554672 DOI: 10.15252/emmm.201809711] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Microglia adopt numerous fates with homeostatic microglia (HM) and a microglial neurodegenerative phenotype (MGnD) representing two opposite ends. A number of variants in genes selectively expressed in microglia are associated with an increased risk for neurodegenerative diseases such as Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD). Among these genes are progranulin (GRN) and the triggering receptor expressed on myeloid cells 2 (TREM2). Both cause neurodegeneration by mechanisms involving loss of function. We have now isolated microglia from Grn−/− mice and compared their transcriptomes to those of Trem2−/−mice. Surprisingly, while loss of Trem2 enhances the expression of genes associated with a homeostatic state, microglia derived from Grn−/− mice showed a reciprocal activation of the MGnD molecular signature and suppression of gene characteristic for HM. The opposite mRNA expression profiles are associated with divergent functional phenotypes. Although loss of TREM2 and progranulin resulted in opposite activation states and functional phenotypes of microglia, FDG (fluoro‐2‐deoxy‐d‐glucose)‐μPET of brain revealed reduced glucose metabolism in both conditions, suggesting that opposite microglial phenotypes result in similar wide spread brain dysfunction.
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Affiliation(s)
- Julia K Götzl
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Georg Werner
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Samira Parhizkar
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Gernot Kleinberger
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | | | - Maximilian Deussing
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Matias Wagner
- Institut für Neurogenomik, Helmholtz Zentrum München, Munich, Germany.,Institut of Human Genetics, Technische Universität München, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Juliane Winkelmann
- Institut für Neurogenomik, Helmholtz Zentrum München, Munich, Germany.,Institut of Human Genetics, Technische Universität München, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | | | - Johannes Levin
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Department of Neurology, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Katrin Fellerer
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Anika Reifschneider
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Sebastian Bultmann
- Department of Biology and Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians-Universität München, Munich, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Axel Rominger
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Sabina Tahirovic
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Scott T Smith
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Charlotte Madore
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Oleg Butovsky
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Evergrande Center for Immunologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Anja Capell
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Haass
- Chair of Metabolic Biochemistry, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany .,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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226
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Willemsen L, de Winther MPJ. Macrophage subsets in atherosclerosis as defined by single-cell technologies. J Pathol 2020; 250:705-714. [PMID: 32003464 PMCID: PMC7217201 DOI: 10.1002/path.5392] [Citation(s) in RCA: 128] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 01/17/2020] [Accepted: 01/29/2020] [Indexed: 12/26/2022]
Abstract
Macrophages play a major role in the pathogenesis of atherosclerosis. Many studies have shone light on the different phenotypes and functions that macrophages can acquire upon exposure to local cues. The microenvironment of the atherosclerotic plaque contains a plethora of macrophage-controlling factors, such as cytokines, oxidised low-density lipoproteins and cell debris. Previous research has determined macrophage function within the plaque mainly by using immunohistochemistry and bulk analysis. The recent development and rapid progress of single-cell technologies, such as cytometry by time of flight and single-cell RNA sequencing, now enable comprehensive mapping of the wide range of cell types and their phenotypes present in atherosclerotic plaques. In this review we discuss recent advances applying these technologies in defining macrophage subsets residing in the atherosclerotic arterial wall of mice and men. Resulting from these studies, we describe three main macrophage subsets: resident-like, pro-inflammatory and anti-inflammatory foamy TREM2hi macrophages, which are found in both mouse and human atherosclerotic plaques. Furthermore, we discuss macrophage subset-specific markers and functions. More insights into the characteristics and phenotype of immune cells within the atherosclerotic plaque may guide future clinical approaches to treat disease. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Lisa Willemsen
- Experimental Vascular Biology, Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Amsterdam UMCUniversity of AmsterdamAmsterdamThe Netherlands
| | - Menno PJ de Winther
- Experimental Vascular Biology, Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Amsterdam UMCUniversity of AmsterdamAmsterdamThe Netherlands
- Institute for Cardiovascular Prevention (IPEK)Ludwig Maximilians UniversityMunichGermany
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227
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Gonzalez-Cotto M, Guo L, Karwan M, Sen SK, Barb J, Collado CJ, Elloumi F, Palmieri EM, Boelte K, Kolodgie FD, Finn AV, Biesecker LG, McVicar DW. TREML4 Promotes Inflammatory Programs in Human and Murine Macrophages and Alters Atherosclerosis Lesion Composition in the Apolipoprotein E Deficient Mouse. Front Immunol 2020; 11:397. [PMID: 32292401 PMCID: PMC7133789 DOI: 10.3389/fimmu.2020.00397] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 02/19/2020] [Indexed: 12/16/2022] Open
Abstract
The Triggering Receptor Expressed on Myeloid cells-like 4 (TREML4) is a member of the TREM receptor family, known modulators of inflammatory responses. We have previously found that TREML4 expression positively correlates with human coronary arterial calcification (CAC). However, the role of TREML4 in the pathogenesis of cardiovascular disease remains incompletely defined. Since macrophages play a key role in inflammatory conditions, we investigated if activated macrophages selectively expressed TREML4 and found that carriage of either one of the eQTL SNP's previously associated with increased TREML4 expression conferred higher expression in human inflammatory macrophages (M1) compared to alternatively activated macrophages (M2). Furthermore, we found that TREML4 expression in human M1 dysregulated several inflammatory pathways related to leukocyte activation, apoptosis and extracellular matrix degradation. Similarly, murine M1 expressed substantial levels of Treml4, as did oxLDL treated macrophages. Transcriptome analysis confirmed that murine Treml4 controls the expression of genes related to inflammation and lipid regulation pathways, suggesting a possible role in atherosclerosis. Analysis of Apoe-/-/Treml4-/- mice showed reduced plaque burden and lesion complexity as indicated by decreased stage scores, macrophage content and collagen deposition. Finally, transcriptome analysis of oxLDL-loaded murine macrophages showed that Treml4 represses a specific set of genes related to carbohydrate, ion and amino acid membrane transport. Metabolomic analysis confirmed that Treml4 deficiency may promote a beneficial relationship between iron homeostasis and glucose metabolism. Together, our results suggest that Treml4 plays a role in the development of cardiovascular disease, as indicated by Treml4-dependent dysregulation of macrophage inflammatory pathways, macrophage metabolism and promotion of vulnerability features in advanced lesions.
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Affiliation(s)
- Marieli Gonzalez-Cotto
- Cancer and Inflammation Program, National Cancer Institute, NIH, Frederick, MD, United States
| | - Liang Guo
- CVPath Institute, Gaithersburg, MD, United States
| | - Megan Karwan
- Laboratory Animal Sciences Program, Leidos Biomedical Research Inc., Cancer and Inflammation Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
| | - Shurjo K. Sen
- Laboratory Animal Sciences Program, Leidos Biomedical Research Inc., Cancer and Inflammation Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
| | - Jennifer Barb
- Mathematical and Statistical Computing Laboratory, Center for Information Technology (CIT), NIH, Bethesda, MD, United States
| | | | - Fathi Elloumi
- Center for Cancer Research Collaborative Bioinformatics Resource, Leidos Biomedical Research, Inc., Bethesda, MD, United States
| | - Erika M. Palmieri
- Cancer and Inflammation Program, National Cancer Institute, NIH, Frederick, MD, United States
| | - Kimberly Boelte
- Cancer and Inflammation Program, National Cancer Institute, NIH, Frederick, MD, United States
| | - Frank D. Kolodgie
- Laboratory Animal Sciences Program, Leidos Biomedical Research Inc., Cancer and Inflammation Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
| | - Aloke V. Finn
- Laboratory Animal Sciences Program, Leidos Biomedical Research Inc., Cancer and Inflammation Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
| | - Leslie G. Biesecker
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, United States
| | - Daniel W. McVicar
- Cancer and Inflammation Program, National Cancer Institute, NIH, Frederick, MD, United States
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228
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Tian H, Shakya A, Chen R, Wang F, Wu W, Li W. Comparative Ligandomic Analysis of Human Lung Epithelial Cells Exposed to PM 2.5. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 2020; 33:165-173. [PMID: 32209175 PMCID: PMC7607556 DOI: 10.3967/bes2020.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/16/2019] [Indexed: 05/30/2023]
Abstract
OBJECTIVE To investigate whether exposure to particulate matter of diameter equal to or less than 2.5 μm (PM 2.5) alters the response of lung epithelial cells to extrinsic regulation by globally profiling cell surface ligands and quantifying their binding activity. METHODS Human A549 lung epithelial cells (LECs) were treated with or without PM 2.5. Ligandomic profiling was applied to these cells for the global identification of LEC-binding ligands with simultaneous quantification of binding activity. Quantitative comparisons of the entire ligandome profiles systematically identified ligands with increased or decreased binding to PM 2.5-treated LECs. RESULTS We found 143 ligands with increased binding to PM 2.5-treated LECs and 404 ligands with decreased binding. Many other ligands showed no change in binding activity. For example, apolipoprotein E (ApoE), Notch2, and growth arrest-specific 6 (Gas6) represent ligands with increased, decreased, or unchanged binding activity, respectively. Both ApoE and Gas6 are phagocytosis ligands, suggesting that phagocytic receptors on LECs after stimulation with PM 2.5 were differentially upregulated by PM 2.5. CONCLUSION These results suggest that the newly-developed ligandomics is a valuable approach to globally profile the response of LECs to PM 2.5 in terms of regulating the expression of cell surface receptors, as quantified by ligand binding activity. This quantitative ligandome profiling will provide in-depth understanding of the LEC molecular response on the cell surface to particulate matter air pollution.
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Affiliation(s)
- Hong Tian
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan, 453003, China
| | - Akhalesh Shakya
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami School of Medicine, Miami, Florida 33136
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Feng Wang
- Department of Genomic Medicine, UT MD Anderson Cancer Center. Houston TX 77054
| | - Weidong Wu
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan, 453003, China
| | - Wei Li
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami School of Medicine, Miami, Florida 33136
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Bonvicini C, Scassellati C, Benussi L, Di Maria E, Maj C, Ciani M, Fostinelli S, Mega A, Bocchetta M, Lanzi G, Giacopuzzi E, Ferraboli S, Pievani M, Fedi V, Defanti CA, Giliani S, Frisoni GB, Ghidoni R, Gennarelli M. Next Generation Sequencing Analysis in Early Onset Dementia Patients. J Alzheimers Dis 2020; 67:243-256. [PMID: 30530974 PMCID: PMC6398561 DOI: 10.3233/jad-180482] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background: Early onset dementias (EOD) are rare neurodegenerative dementias that present before 65 years. Genetic factors have a substantially higher pathogenetic contribution in EOD patients than in late onset dementia. Objective: To identify known and/or novel rare variants in major candidate genes associated to EOD by high-throughput sequencing. Common-risk variants of apolipoprotein E (APOE) and prion protein (PRNP) genes were also assessed. Methods: We studied 22 EOD patients recruited in Memory Clinics, in the context of studies investigating genetic forms of dementia. Two methodological approaches were applied for the target-Next Generation Sequencing (NGS) analysis of these patients. In addition, we performed progranulin plasma dosage, C9Orf72 hexanucleotide repeat expansion analysis, and APOE genotyping. Results: We detected three rare known pathogenic mutations in the GRN and PSEN2 genes and eleven unknown-impact mutations in the GRN, VCP, MAPT, FUS, TREM2, and NOTCH3 genes. Six patients were carriers of only common risk variants (APOE and PRNP), and one did not show any risk mutation/variant. Overall, 69% (n = 9) of our early onset Alzheimer’s disease (EAOD) patients, compared with 34% (n = 13) of sporadic late onset Alzheimer’s disease (LOAD) patients and 27% (n = 73) of non-affected controls (ADNI, whole genome data), were carriers of at least two rare/common risk variants in the analyzed candidate genes panel, excluding the full penetrant mutations. Conclusion: This study suggests that EOD patients without full penetrant mutations are characterized by higher probability to carry polygenic risk alleles that patients with LOAD forms. This finding is in line with recently reported evidence, thus suggesting that the genetic risk factors identified in LOAD might modulate the risk also in EOAD.
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Affiliation(s)
- Cristian Bonvicini
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Catia Scassellati
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Luisa Benussi
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Emilio Di Maria
- Department of Health Sciences, University of Genova and Division of Medical Genetics, Galliera Hospital, Genova, Italy
| | - Carlo Maj
- Genetics Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Institute for Genomic Statistics and Bioinformatics, Bonn, Germany
| | - Miriam Ciani
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Silvia Fostinelli
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Anna Mega
- Laboratory Alzheimer's Neuroimaging and Epidemiology, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Martina Bocchetta
- Laboratory Alzheimer's Neuroimaging and Epidemiology, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Gaetana Lanzi
- A. Nocivelli' Institute for Molecular Medicine Spedali Civili and University of Brescia, Brescia, Italy
| | - Edoardo Giacopuzzi
- Genetics Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Sergio Ferraboli
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Michela Pievani
- Laboratory Alzheimer's Neuroimaging and Epidemiology, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | | | - Carlo Alberto Defanti
- Fondazione Europea Ricerca Biomedica, Centro di Eccellenza Alzheimer, Ospedale Briolini Gazzaniga, Bergamo, Italy
| | - Silvia Giliani
- A. Nocivelli' Institute for Molecular Medicine Spedali Civili and University of Brescia, Brescia, Italy
| | | | - Giovanni Battista Frisoni
- Laboratory Alzheimer's Neuroimaging and Epidemiology, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Laboratory of Neuroimaging of Aging (LANVIE), University Hospitals and University of Geneva, Geneva, Switzerland; Department of Internal Medicine, University Hospitals and University of Geneva, Geneva, Switzerland
| | - Roberta Ghidoni
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Massimo Gennarelli
- Genetics Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
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230
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Nugent AA, Lin K, van Lengerich B, Lianoglou S, Przybyla L, Davis SS, Llapashtica C, Wang J, Kim DJ, Xia D, Lucas A, Baskaran S, Haddick PC, Lenser M, Earr TK, Shi J, Dugas JC, Andreone BJ, Logan T, Solanoy HO, Chen H, Srivastava A, Poda SB, Sanchez PE, Watts RJ, Sandmann T, Astarita G, Lewcock JW, Monroe KM, Di Paolo G. TREM2 Regulates Microglial Cholesterol Metabolism upon Chronic Phagocytic Challenge. Neuron 2020; 105:837-854.e9. [DOI: 10.1016/j.neuron.2019.12.007] [Citation(s) in RCA: 207] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 08/07/2019] [Accepted: 12/04/2019] [Indexed: 12/26/2022]
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231
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232
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Dash R, Choi HJ, Moon IS. Mechanistic insights into the deleterious roles of Nasu-Hakola disease associated TREM2 variants. Sci Rep 2020; 10:3663. [PMID: 32107424 PMCID: PMC7046722 DOI: 10.1038/s41598-020-60561-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 02/13/2020] [Indexed: 02/06/2023] Open
Abstract
Recently, the critical roles played by genetic variants of TREM2 (Triggering Receptor Expressed on Myeloid cells 2) in Alzheimer's disease have been aggressively highlighted. However, few studies have focused on the deleterious roles of Nasu-Hakola disease (NHD) associated TREM2 variants. In order to get insights into the contributions made by these variants to neurodegeneration, we investigated the influences of four NHD associated TREM2 mutations (Y38C, W50C, T66M, and V126G) on loss-of-function, and followed this with in silico prediction and conventional molecular dynamics simulation. NHD mutations were predicted to be highly deleterious by eight different in silico bioinformatics tools and found to induce conformational changes by molecular dynamics simulation. As compared with the wild-type, the four variants produced substantial differences in the collective motions of loop regions, which not only promoted structural remodeling in the CDR2 (complementarity-determining region 2) loop but also in the CDR1 loop, by changing inter- and intra-loop hydrogen bonding networks. In addition, structural studies in a free energy landscape analysis showed that Y38, T66, and V126 are crucial for maintaining the structural features of CDR1 and CDR2 loops, and that mutations in these positions produced steric clashes and loss of ligand binding. These results showed the presence of mutations in the TREM2 ectodomain induced flexibility and caused structural alterations. Dynamical scenarios, as provided by the present study, may be critical to our understanding of the roles of these TREM2 mutations in neurodegenerative diseases.
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Affiliation(s)
- Raju Dash
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea
| | - Ho Jin Choi
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea
| | - Il Soo Moon
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea.
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233
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Hashemiaghdam A, Mroczek M. Microglia heterogeneity and neurodegeneration: The emerging paradigm of the role of immunity in Alzheimer's disease. J Neuroimmunol 2020; 341:577185. [PMID: 32045774 DOI: 10.1016/j.jneuroim.2020.577185] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 02/01/2020] [Accepted: 02/01/2020] [Indexed: 12/22/2022]
Abstract
Alzheimer's disease (AD) is the most common dementia type affecting nearly 44 million people worldwide. Recent findings point to microglia as a significant contributor to neural development, neuroinflammation, and degeneration. Dysregulated immunoactivity in AD has been broadly studied, and current research on animal models enabled us to identify a new cluster of microglia (disease-associated microglia) alongside previously detected glial populations (e.g., plaque-associated microglia, dark microglia, Human Alzheimer's microglia) associated with neuroinflammation and with macrophagic activity. These distinct populations of glia show a spatial distribution within plaques with unique imaging features and distinct gene expression profile. Novel genetic approaches using single-nuclei RNA sequencing (sn-RNA seq) allowed researchers to identify gene expression profiles from fixed human samples. Recent studies, exposing transcriptomic clusters of disease-related cells and analyzing sequenced RNA from sorted myeloid cells, seem to confirm the hypothesis of the central role of glia in the pathogenesis of Alzheimer's disease. These discoveries may shed light on the effects of microglial activation and differences in gene expression profiles, furthering research towards the development of a cell-specific therapy. In this review, we examine recent studies that guide us towards recognizing the role of diverse populations of glial cells and their possible heterogeneous functional states in the pathogenesis of AD in humans.
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Affiliation(s)
| | - Magdalena Mroczek
- The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
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234
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Garcia-Reitboeck P, Phillips A, Piers TM, Villegas-Llerena C, Butler M, Mallach A, Rodrigues C, Arber CE, Heslegrave A, Zetterberg H, Neumann H, Neame S, Houlden H, Hardy J, Pocock JM. Human Induced Pluripotent Stem Cell-Derived Microglia-Like Cells Harboring TREM2 Missense Mutations Show Specific Deficits in Phagocytosis. Cell Rep 2020; 24:2300-2311. [PMID: 30157425 PMCID: PMC6130048 DOI: 10.1016/j.celrep.2018.07.094] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/31/2018] [Accepted: 07/27/2018] [Indexed: 12/22/2022] Open
Abstract
Dysfunction of microglia, the brain’s immune cells, is linked to neurodegeneration. Homozygous missense mutations in TREM2 cause Nasu-Hakola disease (NHD), an early-onset dementia. To study the consequences of these TREM2 variants, we generated induced pluripotent stem cell-derived microglia-like cells (iPSC-MGLCs) from patients with NHD caused by homozygous T66M or W50C missense mutations. iPSC-MGLCs expressed microglial markers and secreted higher levels of TREM2 than primary macrophages. TREM2 expression and secretion were reduced in variant lines. LPS-mediated cytokine secretion was comparable between control and TREM2 variant iPSC-MGLCs, whereas survival was markedly reduced in cells harboring missense mutations when compared with controls. Furthermore, TREM2 missense mutations caused a marked impairment in the phagocytosis of apoptotic bodies, but not in Escherichia coli or zymosan substrates. Coupled with changes in apoptotic cell-induced cytokine release and migration, these data identify specific deficits in the ability of iPSC-MGLCs harboring TREM2 missense mutations to respond to specific pathogenic signals. Generated human microglia-like cells from TREM2 T66M and W50C mutation carriers Heterozygous and homozygous TREM2 variants impair shedding of soluble TREM2 Cytokine secretion not altered in TREM2 variants following LPS exposure Substrate specific impairment of microglial function observed in TREM2 variants
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Affiliation(s)
- Pablo Garcia-Reitboeck
- Department of Neuroinflammation, University College London Institute of Neurology, London WC1N 1PJ, UK; Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Alexandra Phillips
- Department of Neuroinflammation, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Thomas M Piers
- Department of Neuroinflammation, University College London Institute of Neurology, London WC1N 1PJ, UK; Eisai:UCL Therapeutic Innovation Group, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Claudio Villegas-Llerena
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Matt Butler
- Department of Neuroinflammation, University College London Institute of Neurology, London WC1N 1PJ, UK; Eisai:UCL Therapeutic Innovation Group, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Anna Mallach
- Department of Neuroinflammation, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Celia Rodrigues
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Charles E Arber
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Amanda Heslegrave
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Henrik Zetterberg
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK; Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41345, Sweden
| | - Harald Neumann
- Neural Regeneration Group, Institute of Reconstructive Neurobiology, University of Bonn, Bonn 53127, Germany
| | - Stephen Neame
- Neurology Business Group, Hatfield Research Laboratories, Neurology Innovation Centre, Eisai Limited, Hatfield, AL10 9SN, UK
| | - Henry Houlden
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - John Hardy
- Department of Molecular Neuroscience, University College London Institute of Neurology, London WC1N 1PJ, UK
| | - Jennifer M Pocock
- Department of Neuroinflammation, University College London Institute of Neurology, London WC1N 1PJ, UK.
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235
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Bandow K, Hasegawa H, Tomomura M, Tomomura A. Caldecrin inhibits lipopolysaccharide-induced pro-inflammatory cytokines and M1 macrophage polarization through the immunoreceptor triggering receptor expressed in myeloid cells-2. Biochem Biophys Res Commun 2020; 523:1027-1033. [PMID: 31973822 DOI: 10.1016/j.bbrc.2020.01.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/08/2020] [Indexed: 12/14/2022]
Abstract
Caldecrin was previously isolated as a serum calcium-decreasing factor from the pancreas and is known to suppress receptor activator of nuclear factor-κB ligand (RANKL)-induced calcium oscillation pathways in osteoclasts. Here, we explored the effects of caldecrin on lipopolysaccharide (LPS)-Toll-like receptor-4 (TLR-4) signaling pathways in macrophages. Caldecrin inhibited the LPS-induced gene expression of pro-inflammatory cytokines and M1 macrophage polarization in mouse bone marrow macrophages and the RAW264.7 mouse macrophage cell line. Next, we focused on triggering receptor expressed in myeloid cells-2 (TREM-2) as a co-receptor common to RANKL receptor and TLR-4, and established Trem2-KO RAW264.7 cells, in which Trem2 gene was deleted using the CRISPR/Cas9 system. Caldecrin-mediated alterations in pro-inflammatory cytokine expression and M1 macrophage polarization were not observed in Trem2-KO RAW264.7 cells. These results suggest that caldecrin is not only an inhibitor of osteoclast activation but also a negative regulator of LPS-induced inflammatory responses, functioning via TREM-2.
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Affiliation(s)
- Kenjiro Bandow
- Division of Biochemistry, Department of Oral Biology and Tissue Engineering, 1-1 Keyakidai, Sakado, Saitama, 350-0283, Japan
| | - Hiroya Hasegawa
- Division of Orthodontics, Department of Human Development and Fostering, Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama, 350-0283, Japan
| | - Mineko Tomomura
- Division of Biochemistry, Department of Oral Biology and Tissue Engineering, 1-1 Keyakidai, Sakado, Saitama, 350-0283, Japan; Department of Oral Health Sciences, Meikai University School of Health Sciences, 1 Akemi, Urayasu, Chiba, 279-8550, Japan
| | - Akito Tomomura
- Division of Biochemistry, Department of Oral Biology and Tissue Engineering, 1-1 Keyakidai, Sakado, Saitama, 350-0283, Japan.
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236
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Singh AK, Mishra G, Maurya A, Awasthi R, Kumari K, Thakur A, Rai A, Rai GK, Sharma B, Kulkarni GT, Singh SK. Role of TREM2 in Alzheimer's Disease and its Consequences on β- Amyloid, Tau and Neurofibrillary Tangles. Curr Alzheimer Res 2020; 16:1216-1229. [DOI: 10.2174/1567205016666190903102822] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/21/2019] [Accepted: 08/21/2019] [Indexed: 11/22/2022]
Abstract
:
Alzheimer's Disease (AD) is age-related neurodegenerative disorder recognized by a steadily
gradual cognitive decline that has devastating personal and socioeconomic implications. Recently, some
genetic factors for AD have been identified which attracted wide attention of researchers in different
areas of AD biology and possible new therapeutic targets. Alternative forms of triggering receptor expressed
on myeloid cells 2 (TREM2) genes are examples of such risk factors, which contribute higher
risk for developing AD. Comprehending TREM2 function pledge to provide salient insight into how
neuroinflammation contributes to AD pathology. The dearth of microglial TREM2 shepherd to augmented
tau pathology is couple with frequent enhancement of activated neuronal stress kinases. The involvement
of TREM2 in the regulation of tau-associated innate immune response of the CNS has clearly
demonstrated through these findings. However, whether decrease level of TREM2 assists pathology of
tau through changed clearance and pathological escalation of tau or through direct contact between microglia
and neuron and any alternative possible mechanisms need to examine. This review briefly summarizes
distinct functional roles of TREM2 in AD pathology and highlights the TREM2 gene regulation.
We have also addressed the impact of TREM2 on β-amyloid plaques and tau pathology in Alzheimer’s
disease.
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Affiliation(s)
- Anurag K. Singh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India
| | - Gaurav Mishra
- Department of Pharmacy, School of Chemical Sciences & Pharmacy, Central University of Rajasthan, Bandar Sindri, Kishangarh, Ajmer-305817, Rajasthan, India
| | - Anand Maurya
- Department of Pharmacy, School of Chemical Sciences & Pharmacy, Central University of Rajasthan, Bandar Sindri, Kishangarh, Ajmer-305817, Rajasthan, India
| | - Rajendra Awasthi
- Department of Pharmaceutics, Amity Institute of Pharmacy, Amity University Uttar Pradesh, Sector 125, Noida - 201303, India
| | - Komal Kumari
- Department of Pharmacy, School of Chemical Sciences & Pharmacy, Central University of Rajasthan, Bandar Sindri, Kishangarh, Ajmer-305817, Rajasthan, India
| | - Abhimanyu Thakur
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong SAR, China
| | - Arati Rai
- Hygia Institute of Pharmaceutical Education & Research, Lucknow-226020, Uttar Pradesh, India
| | - Gopal Kumar Rai
- Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi- 221005, Uttar Pradesh, India
| | - Bhupesh Sharma
- Department of Pharmacology, Amity Institute of Pharmacy, Amity University Uttar Pradesh, Sector 125, Noida - 201303, India
| | - Giriraj T Kulkarni
- Department of Pharmaceutics, Amity Institute of Pharmacy, Amity University Uttar Pradesh, Sector 125, Noida - 201303, India
| | - Santosh Kumar Singh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India
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Abstract
PURPOSE OF REVIEW Over the last year, research into the immunological and inflammatory signatures of frontotemporal lobar degeneration (FTLD) has accelerated greatly. Herein, we highlight recently proposed roles of brain-resident microglia as well as peripheral myeloid cells in frontotemporal dementia (FTD)-spectrum disorders. RECENT FINDINGS Recent unbiased genetic, transcriptomic, and proteomic surveys using human data confirm significantly altered immune-function genes as well as transcript and protein modules associated with inflammatory and immune function. Beyond human studies, novel animal models indicate important roles for both microglia and monocytes, and central involvement of genes such as Trem2, Apoe, and Tbk1. SUMMARY The importance of neuroinflammatory activity in FTD pathophysiology is unambiguous, but whether this activity is primarily beneficial or detrimental remains unclear, with variable results reported for distinct disease paradigms. Going forward, it will be crucial to determine which types of microglial and peripheral myeloid responses are favorable, in response to which specific proteinopathies, and at which point in disease course.
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238
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Hesse R, Hurtado ML, Jackson RJ, Eaton SL, Herrmann AG, Colom-Cadena M, Tzioras M, King D, Rose J, Tulloch J, McKenzie CA, Smith C, Henstridge CM, Lamont D, Wishart TM, Spires-Jones TL. Comparative profiling of the synaptic proteome from Alzheimer's disease patients with focus on the APOE genotype. Acta Neuropathol Commun 2019; 7:214. [PMID: 31862015 PMCID: PMC6925519 DOI: 10.1186/s40478-019-0847-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 11/13/2019] [Indexed: 12/13/2022] Open
Abstract
Degeneration of synapses in Alzheimer's disease (AD) strongly correlates with cognitive decline, and synaptic pathology contributes to disease pathophysiology. We recently observed that the strongest genetic risk factor for sporadic AD, apolipoprotein E epsilon 4 (APOE4), is associated with exacerbated synapse loss and synaptic accumulation of oligomeric amyloid beta in human AD brain. To begin to understand the molecular cascades involved in synapse loss in AD and how this is mediated by APOE, and to generate a resource of knowledge of changes in the synaptic proteome in AD, we conducted a proteomic screen and systematic in silico analysis of synaptoneurosome preparations from temporal and occipital cortices of human AD and control subjects with known APOE gene status. We examined brain tissue from 33 subjects (7-10 per group). We pooled tissue from all subjects in each group for unbiased proteomic analyses followed by validation with individual case samples. Our analysis identified over 5500 proteins in human synaptoneurosomes and highlighted disease, brain region, and APOE-associated changes in multiple molecular pathways including a decreased abundance in AD of proteins important for synaptic and mitochondrial function and an increased abundance of proteins involved in neuroimmune interactions and intracellular signaling.
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239
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Milà-Alomà M, Suárez-Calvet M, Molinuevo JL. Latest advances in cerebrospinal fluid and blood biomarkers of Alzheimer's disease. Ther Adv Neurol Disord 2019; 12:1756286419888819. [PMID: 31897088 PMCID: PMC6920596 DOI: 10.1177/1756286419888819] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 10/21/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease and its diagnosis has classically been based on clinical symptoms. Recently, a biological rather than a syndromic definition of the disease has been proposed that is based on biomarkers that reflect neuropathological changes. In AD, there are two main biomarker categories, namely neuroimaging and fluid biomarkers [cerebrospinal fluid (CSF) and blood]. As a complex and multifactorial disease, AD biomarkers are important for an accurate diagnosis and to stage the disease, assess the prognosis, test target engagement, and measure the response to treatment. In addition, biomarkers provide us with information that, even if it does not have a current clinical use, helps us to understand the mechanisms of the disease. In addition to the pathological hallmarks of AD, which include amyloid-β and tau deposition, there are multiple concomitant pathological events that play a key role in the disease. These include, but are not limited to, neurodegeneration, inflammation, vascular dysregulation or synaptic dysfunction. In addition, AD patients often have an accumulation of other proteins including α-synuclein and TDP-43, which may have a pathogenic effect on AD. In combination, there is a need to have biomarkers that reflect different aspects of AD pathogenesis and this will be important in the future to establish what are the most suitable applications for each of these AD-related biomarkers. It is unclear whether sex, gender, or both have an effect on the causes of AD. There may be differences in fluid biomarkers due to sex but this issue has often been neglected and warrants further research. In this review, we summarize the current state of the principal AD fluid biomarkers and discuss the effect of sex on these biomarkers.
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Affiliation(s)
- Marta Milà-Alomà
- Barcelonaβeta Brain Research Center (BBRC),
Pasqual Maragall Foundation, Barcelona, Spain
- IMIM (Hospital del Mar Medical Research
Institute), Barcelona
| | - Marc Suárez-Calvet
- Barcelonaβeta Brain Research Center (BBRC),
Pasqual Maragall Foundation, Barcelona, Spain
- IMIM (Hospital del Mar Medical Research
Institute), Barcelona
- Department of Neurology, Hospital del Mar,
Barcelona
| | - José Luís Molinuevo
- Scientific Director, Alzheimer’s Prevention
Program, Barcelonaβeta Brain Research Center, Wellington 30, Barcelona,
08005, Spain
- IMIM (Hospital del Mar Medical Research
Institute), Barcelona
- CIBER Fragilidad y Envejecimiento Saludable,
Madrid, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
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240
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Dean HB, Roberson ED, Song Y. Neurodegenerative Disease-Associated Variants in TREM2 Destabilize the Apical Ligand-Binding Region of the Immunoglobulin Domain. Front Neurol 2019; 10:1252. [PMID: 32021611 PMCID: PMC6985895 DOI: 10.3389/fneur.2019.01252] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 11/11/2019] [Indexed: 01/22/2023] Open
Abstract
Single nucleotide variations in Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) have been linked to both late-onset Alzheimer's disease and behavioral variant frontotemporal dementia (FTD), the latter presenting either in isolation or with cystic bone lesions in a condition called Nasu-Hakola disease. Models of the extracellular domain of TREM2 show that Nasu-Hakola disease-associated mutations are grossly inactivating by truncation, frameshift, or unfolding, that Alzheimer's disease (AD)-associated variants localize to a putative ligand-interacting region (PLIR) on the extracellular surface, and that FTD-associated variants are found in the hydrophobic core. However, while these disease-associated residues are predicted to play some role in disrupting ligand binding to the extracellular domain of TREM2, how they ultimately lead to disease remains unknown. Here, we used in silico molecular modeling to investigate all-atom models of TREM2 and characterize the effects on conformation and dynamical motion of AD-associated R47H and R62H as well as FTD-associated T96K, D86V, and T66M variants compared to the benign N68K variant and the common variant. Our model, which is based on a published 2.2 Å resolution crystal structure of the TREM2 extracellular domain, finds that both AD- and FTD-associated variants cause localized instability in three loops adjacent to the PLIR that correspond to the complementarity-determining regions (CDRs) of antibodies. This instability ultimately disrupts tethering between these CDRs and the core of the immunoglobulin domain, exposing a group of otherwise-buried, negatively charged residues. This instability and exposure of negatively charged residues is most severe following introduction of the T66M variant that has been described as causing FTD even in the heterozygous state and is less severe following introduction of variants that are less strongly tied to FTD or of those associated with AD. Thus, our results provide further evidence that the proposed loss-of-function caused by neurodegenerative disease-associated variants may be driven by altered conformational stability of the ligand-interacting CDR and, ultimately, loss of affinity or specificity for TREM2 ligands.
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Affiliation(s)
- Hunter B Dean
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, United States.,Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, United States.,Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL, United States.,Alzheimer's Disease Center, University of Alabama at Birmingham, Birmingham, AL, United States.,Medical Scientist Training Program, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Erik D Roberson
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, United States.,Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL, United States.,Alzheimer's Disease Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Yuhua Song
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
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241
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Zhong L, Chen XF. The Emerging Roles and Therapeutic Potential of Soluble TREM2 in Alzheimer's Disease. Front Aging Neurosci 2019; 11:328. [PMID: 32038221 PMCID: PMC6988790 DOI: 10.3389/fnagi.2019.00328] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 11/12/2019] [Indexed: 01/14/2023] Open
Abstract
Alzheimer’s disease (AD) is the most common form of dementia characterized by the deposition of extracellular amyloid-β (Aβ)-containing plaques, the formation of intraneuronal neurofibrillary tangles as well as neuroinflammatory changes. As the key player in the brain innate immune system, microglia has now taken a center stage in AD research. A large number of AD risk loci identified by genome-wide association studies are located in or near the genes highly expressed in microglia. Among them, the triggering receptor expressed on myeloid cells 2 (TREM2) has drawn much attention. A rare variant in TREM2 increases AD risk with an odds ratio comparable to the strongest genetic risk factor apolipoprotein ε4 allele. In the past 6 years, extensive studies have dissected the mechanisms by which TREM2 and its variants modulate microglial functions impacting amyloid and tau pathologies in both animal models and human studies. In addition to the full-length TREM2, research on the soluble form of TREM2 (sTREM2) has facilitated the translation of preclinical findings on TREM2. In this review, we summarize our current understanding of the biology and pathobiology of sTREM2 including its origin, its emergence as a disease biomarker, and its potential neuroprotective functions. These aspects are important for understanding the involvement of sTREM2 in AD pathogenesis and may provide novel insights into applying sTREM2 for AD diagnosis and therapy.
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Affiliation(s)
- Li Zhong
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| | - Xiao-Fen Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China.,Shenzhen Research Institute of Xiamen University, Shenzhen, China
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242
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Yao H, Coppola K, Schweig JE, Crawford F, Mullan M, Paris D. Distinct Signaling Pathways Regulate TREM2 Phagocytic and NFκB Antagonistic Activities. Front Cell Neurosci 2019; 13:457. [PMID: 31649511 PMCID: PMC6795686 DOI: 10.3389/fncel.2019.00457] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 09/25/2019] [Indexed: 11/13/2022] Open
Abstract
Several genetic variants of the Triggering Receptor Expressed on Myeloid Cells-2 (TREM2) have been shown to increase the risk of developing Alzheimer’s disease (AD) supporting a role of microglia and immune cells in the pathobiology of AD. We have employed an ectopic model of TREM2 and DAP12 expression in HEK293 cells to study selectively TREM2 dependent signaling and phagocytic functions and evaluated the effects of some of the TREM2 mutations associated with AD. We show that shedding of the TREM2 N-terminal domain does not affect the inhibition of NFκB activation induced by TREM2 while it completely blocks phagocytosis suggesting that TREM2 anti-inflammatory properties can be mediated by the TREM2 C-terminal fragment while the phagocytic activity requires the full-length receptor. In addition, we confirm in that model that apolipoprotein E (APOE) is a ligand for TREM2 and triggers TREM2 signaling. In particular, we show that APOE4 stimulates spleen tyrosine kinase (SYK) activation more potently than APOE2 in a TREM2 dependent manner. Interestingly, TREM2 appears to antagonize NFκB activation induced by phorbol ester but is unable to prevent TNFα induction of NFκB activation suggesting that TREM2 antagonizes inflammatory events triggered downstream of PKC. TREM2 mutations drastically impact TREM2 phagocytosis as well as its ability to antagonize NFκB activation and notably prevent the activation of the PI3K/AKT pathway observed with wild-type TREM2. Overall our data suggest that TREM2 dependent phagocytosis requires an activation of the SYK/PI3K/AKT/PLCγ pathways while the suppression of NFκB activation by TREM2 is independent of SYK, PI3K, and PLCγ activities. This model of ectopic TREM2-DAP12 co-expression appears suitable to study TREM2 signaling as several biological functions of TREM2 and TREM2 mutations that have been previously described in myeloid and microglial cells were also replicated in this model.
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Affiliation(s)
- Hailan Yao
- The Roskamp Institute, Sarasota, FL, United States.,James A. Haley Veterans' Hospital, Tampa, FL, United States
| | - Kyle Coppola
- The Roskamp Institute, Sarasota, FL, United States.,James A. Haley Veterans' Hospital, Tampa, FL, United States
| | - Jonas Elias Schweig
- The Roskamp Institute, Sarasota, FL, United States.,James A. Haley Veterans' Hospital, Tampa, FL, United States
| | - Fiona Crawford
- The Roskamp Institute, Sarasota, FL, United States.,James A. Haley Veterans' Hospital, Tampa, FL, United States
| | - Michael Mullan
- The Roskamp Institute, Sarasota, FL, United States.,James A. Haley Veterans' Hospital, Tampa, FL, United States
| | - Daniel Paris
- The Roskamp Institute, Sarasota, FL, United States.,James A. Haley Veterans' Hospital, Tampa, FL, United States
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243
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Genetic intolerance analysis as a tool for protein science. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183058. [PMID: 31494120 DOI: 10.1016/j.bbamem.2019.183058] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 08/21/2019] [Accepted: 08/30/2019] [Indexed: 01/04/2023]
Abstract
Recent advances in whole genome and exome sequencing have dramatically increased the database of human gene variations. There are now enough sequenced human exomes and genomes to begin to identify gene variations that are notable because they are NOT observed in sequenced human genomes, apparently because they are subject to "purifying selection", exemplifying genetic intolerance. Such "dysprocreative" gene variations are embryonic lethal or prevent reproduction through any one of a number of possible mechanisms. Here we review an emerging quantitative approach, "Missense Tolerance Ratio" (MTR) analysis, that is used to assess protein-encoding gene (cDNA) sequence intolerance to missense mutations based on analysis of the >100 K and growing number of currently available human genome and exome sequences. This approach is already useful for analyzing intolerance to mutations in cDNA segments with a resolution on the order of 90 bases. Moreover, as the number of sequenced genomes/exomes increases by orders of magnitude it may eventually be possible to assess mutational tolerance in a statistically robust manner at or near single site resolution. Here we focus on how cDNA intolerance analysis complements other bioinformatic methods to illuminate structure-folding-function relationships for the encoded proteins. A set of disease-linked membrane proteins is employed to provide examples.
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244
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Fitz NF, Nam KN, Koldamova R, Lefterov I. Therapeutic targeting of nuclear receptors, liver X and retinoid X receptors, for Alzheimer's disease. Br J Pharmacol 2019; 176:3599-3610. [PMID: 30924124 PMCID: PMC6715597 DOI: 10.1111/bph.14668] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/15/2019] [Accepted: 02/24/2019] [Indexed: 12/18/2022] Open
Abstract
After 15 years of research into Alzheimer's disease (AD) therapeutics, including billions of US dollars provided by federal agencies, pharmaceutical companies, and private foundations, there are still no meaningful therapies that can delay the onset or slow the progression of AD. An understanding of the proteolytic processing of amyloid precursor protein (APP) and the hypothesis that pathogenic mechanisms in familial and sporadic forms of AD are very similar led to the assumption that pharmacological inhibition of secretases or immunological approaches to clear amyloid depositions in the brain would have been the core to drug discovery strategies and successful therapies. However, there are other understudied approaches including targeting genes, gene networks, and metabolic pathways outside the proteolytic processing of APP. The advancement of newly developed sequencing technologies and mass spectrometry, as well as the availability of animal models expressing human apolipoprotein E isoforms, has been critical in rationalizing additional AD therapeutics. The purpose of this review is to present one of those approaches, based on the role of ligand-activated nuclear liver X and retinoid X receptors in the brain. This therapeutic approach was initially proposed utilizing in vitro models 15 years ago and has since been examined in numerous studies using AD-like mouse models. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.
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Affiliation(s)
- Nicholas F Fitz
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kyong Nyon Nam
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Radosveta Koldamova
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Iliya Lefterov
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
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245
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Zhang L, Xu J, Gao J, Wu Y, Yin M, Zhao W. CD200-, CX3CL1-, and TREM2-mediated neuron-microglia interactions and their involvements in Alzheimer's disease. Rev Neurosci 2019; 29:837-848. [PMID: 29729150 DOI: 10.1515/revneuro-2017-0084] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/06/2018] [Indexed: 12/20/2022]
Abstract
Neurons and microglia are two major components in the central nervous system (CNS). The interactions between them play important roles in maintaining homeostasis of the brain. In recent years, substantial studies have focused on the interactions between neurons and microglia, revealing that microglia become reactive when the interactions are pathophysiologically interfered, usually accompanying neuronal injury, which is a common feature for Alzheimer's disease (AD). Many molecules and factors participate in these physiological and pathological processes, either in a contact-dependent or a contact-independent manner. Accumulating studies have revealed that in the CNS, cluster of differentiation-200 (CD200) and fractalkine (CX3CL1) expressed mainly on neurons and triggering receptor expressed on myeloid cells 2 (TREM2) expressed mainly on microglia. These molecules can mediate neuron-microglia interactions in a contact-dependent manner and contribute to the pathogenesis of AD. Here, we review the expression, distribution, and function of CD200, CX3CL1, and TREM2 in regulating neuron-microglia interactions under physiological conditions as well as in AD.
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Affiliation(s)
- Lihang Zhang
- School of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Juan Xu
- School of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Jinchao Gao
- School of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yuncheng Wu
- Department of Neurology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, 100 Haining Road, Shanghai 200080, China
| | - Ming Yin
- School of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Wenjuan Zhao
- School of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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246
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Biber K, Bhattacharya A, Campbell BM, Piro JR, Rohe M, Staal RGW, Talanian RV, Möller T. Microglial Drug Targets in AD: Opportunities and Challenges in Drug Discovery and Development. Front Pharmacol 2019; 10:840. [PMID: 31507408 PMCID: PMC6716448 DOI: 10.3389/fphar.2019.00840] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
Alzheimer’s disease (AD) is a large and increasing unmet medical need with no disease-modifying treatment currently available. Genetic evidence from genome-wide association studies (GWASs) and gene network analysis has clearly revealed a key role of the innate immune system in the brain, of which microglia are the most important element. Single-nucleotide polymorphisms (SNPs) in genes predominantly expressed in microglia have been associated with altered risk of developing AD. Furthermore, microglia-specific pathways are affected on the messenger RNA (mRNA) expression level in post-mortem AD tissue and in mouse models of AD. Together these findings have increased the interest in microglia biology, and numerous scientific reports have proposed microglial molecules and pathways as drug targets for AD. Target identification and validation are generally the first steps in drug discovery. Both target validation and drug lead identification for central nervous system (CNS) targets and diseases entail additional significant obstacles compared to peripheral targets and diseases. This makes CNS drug discovery, even with well-validated targets, challenging. In this article, we will illustrate the special challenges of AD drug discovery by discussing the viability/practicality of possible microglia drug targets including cluster of differentiation 33 (CD33), KCa3.1, kynurenines, ionotropic P2 receptor 7 (P2X7), programmed death-1 (PD-1), Toll-like receptors (TLRs), and triggering receptor expressed in myeloid cells 2 (TREM2).
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Affiliation(s)
- Knut Biber
- AbbVie Deutschland GmbH & Co. KG, Neuroscience Research, Ludwigshafen, Germany
| | | | | | - Justin R Piro
- AbbVie Foundational Neuroscience Center, Cambridge, MA, United States
| | - Michael Rohe
- AbbVie Deutschland GmbH & Co. KG, Neuroscience Research, Ludwigshafen, Germany
| | | | - Robert V Talanian
- AbbVie Foundational Neuroscience Center, Cambridge, MA, United States
| | - Thomas Möller
- AbbVie Foundational Neuroscience Center, Cambridge, MA, United States
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247
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Abstract
Microglia are the primary innate immune cells in the CNS. In the healthy brain, they exhibit a unique molecular homeostatic 'signature', consisting of a specific transcriptional profile and surface protein expression pattern, which differs from that of tissue macrophages. In recent years, there have been a number of important advances in our understanding of the molecular signatures of homeostatic microglia and disease-associated microglia that have provided insight into how these cells are regulated in health and disease and how they contribute to the maintenance of the neural environment.
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248
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Shi Y, Holtzman DM. Interplay between innate immunity and Alzheimer disease: APOE and TREM2 in the spotlight. Nat Rev Immunol 2019; 18:759-772. [PMID: 30140051 DOI: 10.1038/s41577-018-0051-1] [Citation(s) in RCA: 368] [Impact Index Per Article: 73.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer disease is more than a pure proteopathy. Chronic neuroinflammation stands out during the pathogenesis of the disease and in turn modulates disease progression. The central nervous system (CNS) is separated from the blood circulation by the blood-brain barrier. In Alzheimer disease, neuroinflammation heavily relies on innate immune responses that are primarily mediated by CNS-resident microglia. APOE (which encodes apolipoprotein E) is the strongest genetic risk factor for Alzheimer disease, and APOE was recently shown to affect the disease in part through its immunomodulatory function. This function of APOE is likely linked to triggering receptor expressed on myeloid cells 2 (TREM2), which is expressed by microglia in the CNS. Here, we review the rapidly growing literature on the role of disease-associated microglia, TREM2 and APOE in the pathogenesis of Alzheimer disease and present an integrated view of innate immune function in Alzheimer disease.
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Affiliation(s)
- Yang Shi
- Department of Neurology, Hope Center for Neurological Disorders, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA
| | - David M Holtzman
- Department of Neurology, Hope Center for Neurological Disorders, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA.
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249
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Dourlen P, Kilinc D, Malmanche N, Chapuis J, Lambert JC. The new genetic landscape of Alzheimer's disease: from amyloid cascade to genetically driven synaptic failure hypothesis? Acta Neuropathol 2019; 138:221-236. [PMID: 30982098 PMCID: PMC6660578 DOI: 10.1007/s00401-019-02004-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/30/2019] [Accepted: 04/02/2019] [Indexed: 12/18/2022]
Abstract
A strong genetic predisposition (60–80% of attributable risk) is present in Alzheimer’s disease (AD). In view of this major genetic component, identification of the genetic risk factors has been a major objective in the AD field with the ultimate aim to better understand the pathological processes. In this review, we present how the genetic risk factors are involved in APP metabolism, β-amyloid peptide production, degradation, aggregation and toxicity, innate immunity, and Tau toxicity. In addition, on the basis of the new genetic landscape, resulting from the recent high-throughput genomic approaches and emerging neurobiological information, we propose an over-arching model in which the focal adhesion pathway and the related cell signalling are key elements in AD pathogenesis. The core of the focal adhesion pathway links the physiological functions of amyloid precursor protein and Tau with the pathophysiological processes they are involved in. This model includes several entry points, fitting with the different origins for the disease, and supports the notion that dysregulation of synaptic plasticity is a central node in AD. Notably, our interpretation of the latest data from genome wide association studies complements other hypotheses already developed in the AD field, i.e., amyloid cascade, cellular phase or propagation hypotheses. Genetically driven synaptic failure hypothesis will need to be further tested experimentally within the general AD framework.
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Affiliation(s)
- Pierre Dourlen
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Devrim Kilinc
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Nicolas Malmanche
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Julien Chapuis
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Jean-Charles Lambert
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France.
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250
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Apolipoprotein E and Alzheimer disease: pathobiology and targeting strategies. Nat Rev Neurol 2019; 15:501-518. [PMID: 31367008 DOI: 10.1038/s41582-019-0228-7] [Citation(s) in RCA: 697] [Impact Index Per Article: 139.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2019] [Indexed: 02/06/2023]
Abstract
Polymorphism in the apolipoprotein E (APOE) gene is a major genetic risk determinant of late-onset Alzheimer disease (AD), with the APOE*ε4 allele conferring an increased risk and the APOE*ε2 allele conferring a decreased risk relative to the common APOE*ε3 allele. Strong evidence from clinical and basic research suggests that a major pathway by which APOE4 increases the risk of AD is by driving earlier and more abundant amyloid pathology in the brains of APOE*ε4 carriers. The number of amyloid-β (Aβ)-dependent and Aβ-independent pathways that are known to be differentially modulated by APOE isoforms is increasing. For example, evidence is accumulating that APOE influences tau pathology, tau-mediated neurodegeneration and microglial responses to AD-related pathologies. In addition, APOE4 is either pathogenic or shows reduced efficiency in multiple brain homeostatic pathways, including lipid transport, synaptic integrity and plasticity, glucose metabolism and cerebrovascular function. Here, we review the recent progress in clinical and basic research into the role of APOE in AD pathogenesis. We also discuss how APOE can be targeted for AD therapy using a precision medicine approach.
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