151
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Sullivan P. Influence of Western diet and APOE genotype on Alzheimer's disease risk. Neurobiol Dis 2020; 138:104790. [DOI: 10.1016/j.nbd.2020.104790] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/28/2020] [Accepted: 02/03/2020] [Indexed: 10/25/2022] Open
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152
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Yang J, Wise L, Fukuchi KI. TLR4 Cross-Talk With NLRP3 Inflammasome and Complement Signaling Pathways in Alzheimer's Disease. Front Immunol 2020; 11:724. [PMID: 32391019 PMCID: PMC7190872 DOI: 10.3389/fimmu.2020.00724] [Citation(s) in RCA: 165] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/30/2020] [Indexed: 01/02/2023] Open
Abstract
Amyloid plaques, mainly composed of abnormally aggregated amyloid β-protein (Aβ) in the brain parenchyma, and neurofibrillary tangles (NFTs), consisting of hyperphosphorylated tau protein aggregates in neurons, are two pathological hallmarks of Alzheimer's disease (AD). Aβ fibrils and tau aggregates in the brain are closely associated with neuroinflammation and synapse loss, characterized by activated microglia and dystrophic neurites. Genome-wide genetic association studies revealed important roles of innate immune cells in the pathogenesis of late-onset AD by recognizing a dozen genetic risk loci that modulate innate immune activities. Furthermore, microglia, brain resident innate immune cells, have been increasingly recognized to play key, opposing roles in AD pathogenesis by either eliminating toxic Aβ aggregates and enhancing neuronal plasticity or producing proinflammatory cytokines, reactive oxygen species, and synaptotoxicity. Aggregated Aβ binds to toll-like receptor 4 (TLR4) and activates microglia, resulting in increased phagocytosis and cytokine production. Complement components are associated with amyloid plaques and NFTs. Aggregated Aβ can activate complement, leading to synapse pruning and loss by microglial phagocytosis. Systemic inflammation can activate microglial TLR4, NLRP3 inflammasome, and complement in the brain, leading to neuroinflammation, Aβ accumulation, synapse loss and neurodegeneration. The host immune response has been shown to function through complex crosstalk between the TLR, complement and inflammasome signaling pathways. Accordingly, targeting the molecular mechanisms underlying the TLR-complement-NLRP3 inflammasome signaling pathways can be a preventive and therapeutic approach for AD.
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Affiliation(s)
- Junling Yang
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, United States
| | - Leslie Wise
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, United States
| | - Ken-Ichiro Fukuchi
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, United States
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153
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Vogt LM, Kwasniewicz E, Talens S, Scavenius C, Bielecka E, Ekdahl KN, Enghild JJ, Mörgelin M, Saxne T, Potempa J, Blom AM. Apolipoprotein E Triggers Complement Activation in Joint Synovial Fluid of Rheumatoid Arthritis Patients by Binding C1q. THE JOURNAL OF IMMUNOLOGY 2020; 204:2779-2790. [PMID: 32253242 DOI: 10.4049/jimmunol.1900372] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 03/10/2020] [Indexed: 12/11/2022]
Abstract
We identified apolipoprotein E (ApoE) as one of the proteins that are found in complex with complement component C4d in pooled synovial fluid of rheumatoid arthritis (RA) patients. Immobilized human ApoE activated both the classical and the alternative complement pathways. In contrast, ApoE in solution demonstrated an isoform-dependent inhibition of hemolysis and complement deposition at the level of sC5b-9. Using electron microscopy imaging, we confirmed that ApoE interacts differently with C1q depending on its context; surface-bound ApoE predominantly bound C1q globular heads, whereas ApoE in a solution favored the hinge/stalk region of C1q. As a model for the lipidated state of ApoE in lipoprotein particles, we incorporated ApoE into phosphatidylcholine/phosphatidylethanolamine liposomes and found that the presence of ApoE on liposomes increased deposition of C1q and C4b from serum when analyzed using flow cytometry. In addition, posttranslational modifications associated with RA, such as citrullination and oxidation, reduced C4b deposition, whereas carbamylation enhanced C4b deposition on immobilized ApoE. Posttranslational modification of ApoE did not alter C1q interaction but affected binding of complement inhibitors factor H and C4b-binding protein. This suggests that changed ability of C4b to deposit on modified ApoE may play an important role. Our data show that posttranslational modifications of ApoE alter its interactions with complement. Moreover, ApoE may play different roles in the body depending on its solubility, and in diseased states such as RA, deposited ApoE may induce local complement activation rather than exert its typical role of inhibition.
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Affiliation(s)
- Leonie M Vogt
- Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, 21428 Malmö, Sweden
| | - Ewa Kwasniewicz
- Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, 21428 Malmö, Sweden
| | - Simone Talens
- Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, 21428 Malmö, Sweden
| | - Carsten Scavenius
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Ewa Bielecka
- Malopolska Centre of Biotechnology, Jagiellonian University, PL-30-387 Kraków, Poland
| | - Kristina N Ekdahl
- Rudbeck Laboratory, Department of Immunology, Genetics, and Pathology, Uppsala University, 751 85 Uppsala, Sweden.,Linnaeus Centre for Biomaterials Chemistry, Linnaeus University, 391 82 Kalmar, Sweden
| | - Jan J Enghild
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Matthias Mörgelin
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, 221 84 Lund, Sweden
| | - Tore Saxne
- Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, S-22185 Lund, Sweden
| | - Jan Potempa
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland; and.,Department of Oral Immunity and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY 40202
| | - Anna M Blom
- Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, 21428 Malmö, Sweden;
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154
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Goldberg BS, Ackerman ME. Antibody-mediated complement activation in pathology and protection. Immunol Cell Biol 2020; 98:305-317. [PMID: 32142167 DOI: 10.1111/imcb.12324] [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: 10/24/2019] [Revised: 02/27/2020] [Accepted: 03/03/2020] [Indexed: 01/10/2023]
Abstract
Antibody-dependent complement activity is associated not only with autoimmune morbidity, but also with antitumor efficacy. In infectious disease, both recombinant monoclonal antibodies and polyclonal antibodies generated in natural adaptive responses can mediate complement activity to protective, therapeutic or disease-enhancing effect. Recent advances have contributed to the structural resolution of molecular complexes involved in antibody-mediated complement activation, defining the avid nature of participating interactions and pointing to how antibody isotype, subclass, hinge flexibility, glycosylation state, amino acid sequence and the contextual nature of the cognate antigen/epitope are all factors that can determine complement activity through impact on antibody multimerization and subsequent recruitment of complement component 1q. Beyond the efficiency of activation, complement activation products interact with various cell types that mediate immune adherence, trafficking, immune education and innate functions. Similarly, depending on the anatomical location and extent of activation, complement can support homeostatic restoration or be leveraged by pathogens or neoplasms to enhance infection or promote tumorigenic microenvironments, respectively. Advances in means to suppress complement activation by intravenous immunoglobulin (IVIG), IVIG mimetics and complement-intervening antibodies represent proven and promising exploratory therapeutic strategies, while antibody engineering has likewise offered frameworks to enhance, eliminate or isolate complement activation to interrogate in vivo mechanisms of action. Such strategies promise to support the optimization of antibody-based drugs that are able to tackle emerging and difficult-to-treat diseases by improving our understanding of the synergistic and antagonistic relationships between antibody mechanisms mediated by Fc receptors, direct binding and the products of complement activation.
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Affiliation(s)
| | - Margaret E Ackerman
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
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155
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156
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Xie CB, Jane-Wit D, Pober JS. Complement Membrane Attack Complex: New Roles, Mechanisms of Action, and Therapeutic Targets. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1138-1150. [PMID: 32194049 DOI: 10.1016/j.ajpath.2020.02.006] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/24/2020] [Accepted: 02/03/2020] [Indexed: 12/11/2022]
Abstract
The complement membrane attack complex (MAC) is classically known as a cytolytic effector of innate and adaptive immunity that forms pores in the plasma membrane of pathogens or targeted cells, leading to osmolysis. Nucleated cells resist MAC-mediated cytolysis by expression of inhibitors that block MAC assembly or by rapid removal of MAC through endocytosis or shedding. In the absence of lysis, MAC may induce intracellular signaling and cell activation, responses implicated in a variety of autoimmune, inflammatory, and transplant disease settings. New discoveries into the structure and biophysical properties of MAC revealed heterogeneous MAC precursors and conformations that provide insights into MAC function. In addition, new mechanisms of MAC-mediated signaling and its contribution to disease pathogenesis have recently come to light. MAC-activated cells have been found to express proinflammatory proteins-often through NF-κB-dependent transcription, assemble inflammasomes, enabling processing, and facilitate secretion of IL-1β and IL-18, as well as other signaling pathways. These recent insights into the mechanisms of action of MAC provide an updated framework to therapeutic approaches that can target MAC assembly, signaling, and proinflammatory effects in various complement-mediated diseases.
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Affiliation(s)
- Catherine B Xie
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut
| | - Dan Jane-Wit
- Division of Cardiovascular Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Jordan S Pober
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut.
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157
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Cui H, Jiang D, Banerjee S, Xie N, Kulkarni T, Liu RM, Duncan SR, Liu G. Monocyte-derived alveolar macrophage apolipoprotein E participates in pulmonary fibrosis resolution. JCI Insight 2020; 5:134539. [PMID: 32027623 PMCID: PMC7141408 DOI: 10.1172/jci.insight.134539] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 01/30/2020] [Indexed: 12/14/2022] Open
Abstract
Recent studies have presented compelling evidence that it is not tissue-resident, but rather monocyte-derived alveolar macrophages (TR-AMs and Mo-AMs, respectively) that are essential to development of experimental lung fibrosis. However, whether apolipoprotein E (ApoE), which is produced abundantly by Mo-AMs in the lung, plays a role in the pathogenesis is unclear. In this study, we found that pulmonary ApoE was almost exclusively produced by Mo-AMs in mice with bleomycin-induced lung fibrosis. We showed that, although ApoE was not necessary for developing maximal fibrosis in bleomycin-injured lung, it was required for the resolution of this pathology. We found that ApoE directly bound to Collagen I and mediated Collagen I phagocytosis in vitro and in vivo, and this process was dependent on low-density lipoprotein receptor-related protein 1 (LPR1). Furthermore, interference of ApoE/LRP1 interaction impaired the resolution of lung fibrosis in bleomycin-treated WT mice. In contrast, supplementation of ApoE promoted this process in ApoE-/- animals. In conclusion, Mo-AM-derived ApoE is beneficial to the resolution of lung fibrosis, supporting the notion that Mo-AMs may have distinct functions in different phases of lung fibrogenesis. The findings also suggest a potentially novel therapeutic target for treating lung fibrosis, to which effective remedies remain scarce.
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Affiliation(s)
- Huachun Cui
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Dingyuan Jiang
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Pulmonary and Critical Care Medicine, Center of Respiratory Medicine, China-Japan Friendship Hospital, National Clinical Research Center for Respiratory Diseases, Beijing, China
| | - Sami Banerjee
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Na Xie
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Tejaswini Kulkarni
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Rui-Ming Liu
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Steven R. Duncan
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Gang Liu
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
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158
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Keep RF, Jones HC, Drewes LR. This was the year that was: brain barriers and brain fluid research in 2019. Fluids Barriers CNS 2020; 17:20. [PMID: 32138786 PMCID: PMC7059280 DOI: 10.1186/s12987-020-00181-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This editorial highlights advances in brain barrier and brain fluid research published in 2019, as well as addressing current controversies and pressing needs. Topics include recent advances related to: the cerebral endothelium and the neurovascular unit; the choroid plexus, arachnoid membrane; cerebrospinal fluid and the glymphatic hypothesis; the impact of disease states on brain barriers and brain fluids; drug delivery to the brain; and translation of preclinical data to the clinic. This editorial also mourns the loss of two important figures in the field, Malcolm B. Segal and Edward G. Stopa.
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Affiliation(s)
- Richard F. Keep
- Department of Neurosurgery, University of Michigan, R5018 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200 USA
| | | | - Lester R. Drewes
- Department of Biomedical Sciences, University of Minnesota Medical School Duluth, Duluth, MN 55812 USA
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159
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Singhrao SK, Harding A. Is Alzheimer's disease a polymicrobial host microbiome dysbiosis? Expert Rev Anti Infect Ther 2020; 18:275-277. [PMID: 32048530 DOI: 10.1080/14787210.2020.1729741] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Sim K Singhrao
- Dementia and Neurodegenerative Diseases Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Alice Harding
- Dementia and Neurodegenerative Diseases Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
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160
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β-hydroxybutyrate Impedes the Progression of Alzheimer's Disease and Atherosclerosis in ApoE-Deficient Mice. Nutrients 2020; 12:nu12020471. [PMID: 32069870 PMCID: PMC7071244 DOI: 10.3390/nu12020471] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 02/11/2020] [Accepted: 02/12/2020] [Indexed: 01/05/2023] Open
Abstract
β-hydroxybutyrate (β-OHB) has been shown to exert an anti-inflammatory activity. Apolipoprotein-E (ApoE) is strongly associated with atherosclerosis and Alzheimer's disease (AD). This study aimed to explore the therapeutic effect of β-OHB in the brain and the aorta of high-fat diet (HFD)-fed ApoE-deficient mice. We found in Apo-E deficient mice that β-OHB attenuated lipid deposition in the choroid plexus (ChP) and decreased amyloid plaque in the substantia nigra pars compacta. We also found decreased CD68-positive macroglia infiltration of the ChP in β-OHB-treated ApoE-deficient mice. β-OHB treatment ameliorated IgG extravasation into the hippocampal region of the brain. In vitro study using ChP mice cell line revealed that β-OHB attenuated oxidized low-density lipoprotein-induced ApoE-specific differentially expressed inflammatory ChP genes. Treatment with β-OHB reduced aortic plaque formation without affecting blood lipid profiles and decreased serum production of resistin, a well-established risk factor for both AD and atherosclerosis. Thus, the current study suggests and describes the therapeutic potential of β-OHB for the treatment of AD and atherosclerosis.
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161
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162
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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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163
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Fuior EV, Gafencu AV. Apolipoprotein C1: Its Pleiotropic Effects in Lipid Metabolism and Beyond. Int J Mol Sci 2019; 20:ijms20235939. [PMID: 31779116 PMCID: PMC6928722 DOI: 10.3390/ijms20235939] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/19/2019] [Accepted: 11/21/2019] [Indexed: 12/20/2022] Open
Abstract
Apolipoprotein C1 (apoC1), the smallest of all apolipoproteins, participates in lipid transport and metabolism. In humans, APOC1 gene is in linkage disequilibrium with APOE gene on chromosome 19, a proximity that spurred its investigation. Apolipoprotein C1 associates with triglyceride-rich lipoproteins and HDL and exchanges between lipoprotein classes. These interactions occur via amphipathic helix motifs, as demonstrated by biophysical studies on the wild-type polypeptide and representative mutants. Apolipoprotein C1 acts on lipoprotein receptors by inhibiting binding mediated by apolipoprotein E, and modulating the activities of several enzymes. Thus, apoC1 downregulates lipoprotein lipase, hepatic lipase, phospholipase A2, cholesterylester transfer protein, and activates lecithin-cholesterol acyl transferase. By controlling the plasma levels of lipids, apoC1 relates directly to cardiovascular physiology, but its activity extends beyond, to inflammation and immunity, sepsis, diabetes, cancer, viral infectivity, and-not last-to cognition. Such correlations were established based on studies using transgenic mice, associated in the recent years with GWAS, transcriptomic and proteomic analyses. The presence of a duplicate gene, pseudogene APOC1P, stimulated evolutionary studies and more recently, the regulatory properties of the corresponding non-coding RNA are steadily emerging. Nonetheless, this prototypical apolipoprotein is still underexplored and deserves further research for understanding its physiology and exploiting its therapeutic potential.
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Affiliation(s)
- Elena V. Fuior
- Institute of Cellular Biology and Pathology “N. Simionescu”, 050568 Bucharest, Romania;
| | - Anca V. Gafencu
- Institute of Cellular Biology and Pathology “N. Simionescu”, 050568 Bucharest, Romania;
- Correspondence:
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164
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Donat C, Thanei S, Trendelenburg M. Binding of von Willebrand Factor to Complement C1q Decreases the Phagocytosis of Cholesterol Crystals and Subsequent IL-1 Secretion in Macrophages. Front Immunol 2019; 10:2712. [PMID: 31824501 PMCID: PMC6881245 DOI: 10.3389/fimmu.2019.02712] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/05/2019] [Indexed: 12/17/2022] Open
Abstract
Complement C1q, the initiation molecule of the classical pathway, exerts various immunomodulatory functions independent of complement activation. Non-classical functions of C1q include the clearance of apoptotic cells and cholesterol crystals (CC), as well as the modulation of cytokine secretion by immune cells such as macrophages. Moreover, C1q has been shown to act as a binding partner for von Willebrand factor (vWF), initiation molecule of primary hemostasis. However, the consequences of this C1q-vWF interaction on the phagocytosis of CC by macrophages has remained elusive until now. Here, we used CC-C1q-vWF complexes to study immunological effects on human monocyte-derived macrophages (HMDMs). HMDMs were investigated by analyzing surface receptor expression, phagocytosis of CC complexes, cytokine secretion, and caspase-1 activity. We found that vWF only bound to CC in a C1q-dependent manner. Exposure of macrophages to CC-C1q-vWF complexes resulted in an upregulated expression of phagocytosis-mediating receptors MerTK, LRP-1, and SR-A1 as well as CD14, LAIR1, and PD-L1 when compared to CC-C1q without vWF, whereas phagocytosis of CC-C1q complexes was hampered in the presence of vWF. In addition, we observed a diminished caspase-1 activation and subsequent reduction in pro-inflammatory IL-1β cytokine secretion, IL-1β/IL-1RA ratio and IL-1α/IL-1RA ratio. In conclusion, our results demonstrate that vWF binding to C1q substantially modulates the effects of C1q on HMDMs. In this way, the C1q-vWF interaction might be beneficial in dampening inflammation, e.g., in the context of atherosclerosis.
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Affiliation(s)
- Claudia Donat
- Laboratory of Clinical Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Sophia Thanei
- Laboratory of Clinical Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Marten Trendelenburg
- Laboratory of Clinical Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland.,Division of Internal Medicine, University Hospital of Basel, Basel, Switzerland
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165
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Lee JD, Coulthard LG, Woodruff TM. Complement dysregulation in the central nervous system during development and disease. Semin Immunol 2019; 45:101340. [PMID: 31708347 DOI: 10.1016/j.smim.2019.101340] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 10/15/2019] [Accepted: 10/24/2019] [Indexed: 12/14/2022]
Abstract
The complement cascade is an important arm of the immune system that plays a key role in protecting the central nervous system (CNS) from infection. Recently, it has also become clear that complement proteins have fundamental roles in the developing and aging CNS that are distinct from their roles in immunity. During neurodevelopment, complement signalling is involved in diverse processes including neural tube closure, neural progenitor proliferation and differentiation, neuronal migration, and synaptic pruning. In acute neurotrauma and ischamic brain injury, complement drives inflammation and neuronal death, but also neuroprotection and regeneration. In diseases of the aging CNS including dementias and motor neuron disease, chronic complement activation is associated with glial activation, and synapse and neuron loss. Proper regulation of complement is thus essential to allow for an appropriately developed CNS and prevention of excessive damage following neurotrauma or during neurodegeneration. This review provides a comprehensive overview of the evidence for functional roles of complement in brain formation, and its dysregulation during acute and chronic disease. We also provide working models for how complement can lead to neurodevelopmental disorders such as schizophrenia and autism, and either protect, or propagate neurodegenerative diseases including Alzheimer's disease and amyotrophic lateral sclerosis.
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Affiliation(s)
- John D Lee
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Liam G Coulthard
- Royal Brisbane and Women's Hospital, Herston, Australia; School of Clinical Medicine, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Trent M Woodruff
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Australia.
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166
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Bathini P, Brai E, Auber LA. Olfactory dysfunction in the pathophysiological continuum of dementia. Ageing Res Rev 2019; 55:100956. [PMID: 31479764 DOI: 10.1016/j.arr.2019.100956] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/29/2019] [Accepted: 08/26/2019] [Indexed: 12/21/2022]
Abstract
Sensory capacities like smell, taste, hearing, vision decline with aging, but increasing evidence show that sensory dysfunctions are one of the early signs diagnosing the conversion from physiological to pathological brain state. Smell loss represents the best characterized sense in clinical practice and is considered as one of the first preclinical signs of Alzheimer's and Parkinson's disease, occurring a decade or more before the onset of cognitive and motor symptoms. Despite the numerous scientific reports and the adoption in clinical practice, the etiology of sensory damage as prodromal of dementia remains largely unexplored and more studies are needed to resolve the mechanisms underlying sensory network dysfunction. Although both cognitive and sensory domains are progressively affected, loss of sensory experience in early stages plays a major role in reducing the autonomy of demented people in their daily tasks or even possibly contributing to their cognitive decline. Interestingly, the chemosensory circuitry is devoid of a blood brain barrier, representing a vulnerable port of entry for neurotoxic species that can spread to the brain. Furthermore, the exposure of the olfactory system to the external environment make it more susceptible to mechanical injury and trauma, which can cause degenerative neuroinflammation. In this review, we will summarize several findings about chemosensory impairment signing the conversion from healthy to pathological brain aging and we will try to connect those observations to the promising research linking environmental influences to sporadic dementia. The scientific body of knowledge will support the use of chemosensory diagnostics in the presymptomatic stages of AD and other biomarkers with the scope of finding treatment strategies before the onset of the disease.
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Affiliation(s)
- Praveen Bathini
- Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Emanuele Brai
- VIB-KU Leuven Center for Brain & Disease Research, Laboratory for the Research of Neurodegenerative Diseases, Leuven, Belgium
| | - Lavinia Alberi Auber
- Department of Medicine, University of Fribourg, Fribourg, Switzerland; Swiss Integrative Center of Human Health, Fribourg, Switzerland.
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167
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Olsen I, Singhrao SK. Is there a link between genetic defects in the complement cascade and Porphyromonas gingivalis in Alzheimer's disease? J Oral Microbiol 2019; 12:1676486. [PMID: 31893014 PMCID: PMC6818111 DOI: 10.1080/20002297.2019.1676486] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 09/17/2019] [Indexed: 12/18/2022] Open
Abstract
Defects, as determined by Genome-Wide Association Studies (GWAS), in the complement cascade of innate immunity have been suggested to play a key role in Alzheimer's disease (AD). These defective genes encode sub-component 1s (C1s), complement receptor 1, complement component 9, and clusterin, a fluid-phase regulatory protein. A dysregulated complement cascade has been shown to relate to cell activation, defective complement mediated clearance and possible cognitive decline in AD patients. Porphyromonas gingivalis, a putative keystone pathogen of periodontal disease, has been reported to be associated with human AD. The inflammatory burden following experimental oral infection in mice and putative entry of this bacterium into the brain appears to drive the formation of amyloid-beta plaques and neurofibrillary tangles with loss of cognition. P. gingivalis is a master of immune subversion in this inflammatory cascade and may establish microbial dysbiosis where it is located. Here we discuss if P. gingivalis may enhance the detrimental effects of the defective GWAS complement cascade protein genes.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Sim K Singhrao
- Dementia and Neurodegenerative Diseases Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
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168
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Isacson O, Brekk OR, Hallett PJ. Novel Results and Concepts Emerging From Lipid Cell Biology Relevant to Degenerative Brain Aging and Disease. Front Neurol 2019; 10:1053. [PMID: 31649605 PMCID: PMC6794469 DOI: 10.3389/fneur.2019.01053] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/17/2019] [Indexed: 01/26/2023] Open
Abstract
While very rare familial forms of proteinopathy can cause Parkinson's disease (PD), Lewy body dementia (LBD) and age-related dementias, recent in-depth studies of lipid disturbances in the majority of the common forms of these diseases instead suggest a primary pathogenesis in lipid pathways. This review synthesizes a perspective from new data that point to an interdependence of lipids and proteinopathy. This article describes disturbed relationships in lipid homeostasis that causes neuropathology to develop over time and with age, which includes altered mechanisms of glia-neuron exchange of lipids and inflammatory signals.
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Affiliation(s)
- Ole Isacson
- McLean Hospital and Harvard Medical School, Neuroregeneration Research Institute, Belmont, MA, United States
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169
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Islam T, Gharibyan AL, Golchin SA, Pettersson N, Brännström K, Hedberg I, Virta MM, Olofsson L, Olofsson A. Apolipoprotein E impairs amyloid-β fibril elongation and maturation. FEBS J 2019; 287:1208-1219. [PMID: 31571352 DOI: 10.1111/febs.15075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/18/2019] [Accepted: 09/27/2019] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) is strongly linked to amyloid depositions of the Aβ peptide (Aβ). The lipid-binding protein apolipoprotein E (ApoE) has been found to interfere with Aβ amyloid formation and to exert a strong clinical impact to the pathology of AD. The APOE gene exists in three allelic isoforms represented by APOE ε2, APOE ε3, and APOE ε4. Carriers of the APOE ε4 variant display a gene dose-dependent increased risk of developing the disease. Aβ amyloids are formed via a nucleation-dependent mechanism where free monomers are added onto a nucleus in a template-dependent manner. Using a combination of surface plasmon resonance and thioflavin-T assays, we here show that ApoE can target the process of fibril elongation and that its interference effectively prevents amyloid maturation. We expose a complex equilibrium where the concentration of ApoE, Aβ monomers, and the amount of already formed Aβ fibrils will affect the relative proportion and formation rate of mature amyloids versus alternative assemblies. The result illustrates a mechanism which may affect both the clearance rate of Aβ assemblies in vivo and the population of cytotoxic Aβ assemblies.
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Affiliation(s)
- Tohidul Islam
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Anna L Gharibyan
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Solmaz A Golchin
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Nina Pettersson
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | | | - Isabell Hedberg
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Merit-Miriam Virta
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Linnea Olofsson
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Anders Olofsson
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
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170
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Çakici N, van Beveren NJM, Judge-Hundal G, Koola MM, Sommer IEC. An update on the efficacy of anti-inflammatory agents for patients with schizophrenia: a meta-analysis. Psychol Med 2019; 49:2307-2319. [PMID: 31439071 PMCID: PMC6763537 DOI: 10.1017/s0033291719001995] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 07/04/2019] [Accepted: 07/16/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Accumulating evidence shows that a propensity towards a pro-inflammatory status in the brain plays an important role in schizophrenia. Anti-inflammatory drugs might compensate this propensity. This study provides an update regarding the efficacy of agents with some anti-inflammatory actions for schizophrenia symptoms tested in randomized controlled trials (RCTs). METHODS PubMed, Embase, the National Institutes of Health website (http://www.clinicaltrials.gov), and the Cochrane Database of Systematic Reviews were systematically searched for RCTs that investigated clinical outcomes. RESULTS Our search yielded 56 studies that provided information on the efficacy of the following components on symptom severity: aspirin, bexarotene, celecoxib, davunetide, dextromethorphan, estrogens, fatty acids, melatonin, minocycline, N-acetylcysteine (NAC), pioglitazone, piracetam, pregnenolone, statins, varenicline, and withania somnifera extract. The results of aspirin [mean weighted effect size (ES): 0.30; n = 270; 95% CI (CI) 0.06-0.54], estrogens (ES: 0.78; n = 723; CI 0.36-1.19), minocycline (ES: 0.40; n = 946; CI 0.11-0.68), and NAC (ES: 1.00; n = 442; CI 0.60-1.41) were significant in meta-analysis of at least two studies. Subgroup analysis yielded larger positive effects for first-episode psychosis (FEP) or early-phase schizophrenia studies. Bexarotene, celecoxib, davunetide, dextromethorphan, fatty acids, pregnenolone, statins, and varenicline showed no significant effect. CONCLUSIONS Some, but not all agents with anti-inflammatory properties showed efficacy. Effective agents were aspirin, estrogens, minocycline, and NAC. We observed greater beneficial results on symptom severity in FEP or early-phase schizophrenia.
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Affiliation(s)
- N. Çakici
- Department of Psychiatry and Amsterdam Neuroscience, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
- Antes Center for Mental Health Care, Albrandswaardsedijk 74, 3172 AA, Poortugaal, the Netherlands
| | - N. J. M. van Beveren
- Antes Center for Mental Health Care, Albrandswaardsedijk 74, 3172 AA, Poortugaal, the Netherlands
- Department of Psychiatry, Erasmus Medical Center, Doctor Molewaterplein 40, 3015 GD Rotterdam, the Netherlands
- Department of Neuroscience, Erasmus Medical Center, Doctor Molewaterplein 40, 3015 GD Rotterdam, the Netherlands
| | - G. Judge-Hundal
- Antes Center for Mental Health Care, Albrandswaardsedijk 74, 3172 AA, Poortugaal, the Netherlands
- Department of Psychiatry and Biomedical Sciences of Cells and Systems, University Medical Center Groningen, Deusinglaan 2, 9713AW Groningen, the Netherlands
| | - M. M. Koola
- Department of Psychiatry and Behavioral Sciences, George Washington University School of Medicine and Health Sciences, 2300I St NW, Washington, DC 20052, USA
| | - I. E. C. Sommer
- Department of Psychiatry and Biomedical Sciences of Cells and Systems, University Medical Center Groningen, Deusinglaan 2, 9713AW Groningen, the Netherlands
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171
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Abstract
Sporadic Alzheimer's disease is the most common neurodegenerative disorder and represents a very important public healthcare problem with a devastating economic burden for industrialized countries. Recent knowledge acquired from experimental, epidemiological, radiological and genome-wide association studies (GWAS) underline the role of the innate immune system in the pathophysiology of this disease. This article reviews and discusses the function of the cerebral innate immune system, the newly discovered genes associated with the disease development and the experimental evidence around the role of microglia in the onset and progression of Alzheimer's disease. The discovery of different microglia phenotypes associated with the pathology as well as new molecular players will enable the development of new preventive and therapeutic strategies by modulating neuroinflammation in neurodegenerative diseases.
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172
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Bales KR, Paul SM. Targeting apolipoprotein E for treating Alzheimer's disease. Neurosci Lett 2019; 709:134366. [PMID: 31336138 DOI: 10.1016/j.neulet.2019.134366] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/24/2019] [Accepted: 07/02/2019] [Indexed: 01/22/2023]
Abstract
The ε4 allele of the apolipoprotein E gene represents the most widely reproduced and robust susceptibility loci for the most common late onset and sporadic forms of Alzheimer's disease. While the discovery of this now widely replicated association was reported more than 25 years ago, few therapeutic interventions that specifically target the apolipoprotein pathway in brain have emerged. Here we discuss our current understanding of apolipoprotein E biology in brain, its relationship to the pathogenesis of Alzheimer's disease and present potential future avenues for exploration that may be amenable to drug development.
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Affiliation(s)
- Kelly R Bales
- Neuroscience Discovery, Roche Pharma Research & Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel, Switzerland.
| | - Steven M Paul
- Karuna Therapeutics, Inc., Boston, MA, United States
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173
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Bohlen CJ, Friedman BA, Dejanovic B, Sheng M. Microglia in Brain Development, Homeostasis, and Neurodegeneration. Annu Rev Genet 2019; 53:263-288. [PMID: 31518519 DOI: 10.1146/annurev-genet-112618-043515] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Advances in human genetics have implicated a growing number of genes in neurodegenerative diseases, providing insight into pathological processes. For Alzheimer disease in particular, genome-wide association studies and gene expression studies have emphasized the pathogenic contributions from microglial cells and motivated studies of microglial function/dysfunction. Here, we summarize recent genetic evidence for microglial involvement in neurodegenerative disease with a focus on Alzheimer disease, for which the evidence is most compelling. To provide context for these genetic discoveries, we discuss how microglia influence brain development and homeostasis, how microglial characteristics change in disease, and which microglial activities likely influence the course of neurodegeneration. In all, we aim to synthesize varied aspects of microglial biology and highlight microglia as possible targets for therapeutic interventions in neurodegenerative disease.
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Affiliation(s)
- Christopher J Bohlen
- Department of Neuroscience, Genentech, South San Francisco, California 94080, USA; ,
| | - Brad A Friedman
- Department of Bioinformatics, Genentech, South San Francisco, California 94080, USA
| | - Borislav Dejanovic
- Department of Neuroscience, Genentech, South San Francisco, California 94080, USA; ,
| | - Morgan Sheng
- Department of Neuroscience, Genentech, South San Francisco, California 94080, USA; ,
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174
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Martin-Ventura JL, Martinez-Lopez D, Roldan-Montero R, Gomez-Guerrero C, Blanco-Colio LM. Role of complement system in pathological remodeling of the vascular wall. Mol Immunol 2019; 114:207-215. [PMID: 31377677 DOI: 10.1016/j.molimm.2019.06.016] [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: 04/26/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 11/28/2022]
Abstract
Cardiovascular diseases (CVD) remain the major cause of morbidity and mortality in Europe. The clinical complications associated to arterial wall rupture involve intimal cap rupture in complicated atherosclerotic plaques and medial rupture in abdominal aortic aneurysm (AAA). The mechanisms underlying pathological vascular remodeling include lipid accumulation, cell proliferation, redox imbalance, proteolysis, leukocyte infiltration, cell death, and eventually, thrombosis. The complement system could participate in vascular remodeling by several mechanisms, from an initial protective response that aims in the clearing of cell debris to a potential deleterious role participating in leukocyte chemotaxis and cell activation and bridging innate and adaptive immunity. We have reviewed the presence and distribution of complement components, as well as the triggers of complement activation in atherosclerotic plaques and AAA, to later assess the functional consequences of complement modulation in experimental models of pathological vascular remodeling and the potential role of complement components as potential circulating biomarkers of CVD. On the whole, complement system is a key mechanism involved in vascular remodelling, which could be useful in the diagnostic/prognostic setting, as well as a potential therapeutic target, of CVD.
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Affiliation(s)
- Jose Luis Martin-Ventura
- Vascular Research Lab, IIS-Fundación Jiménez Díaz, Universidad Autonoma de Madrid, and CIBERCV, Spain.
| | - Diego Martinez-Lopez
- Vascular Research Lab, IIS-Fundación Jiménez Díaz, Universidad Autonoma de Madrid, and CIBERCV, Spain
| | - Raquel Roldan-Montero
- Vascular Research Lab, IIS-Fundación Jiménez Díaz, Universidad Autonoma de Madrid, and CIBERCV, Spain
| | - Carmen Gomez-Guerrero
- Vascular Research Lab, IIS-Fundación Jiménez Díaz, Universidad Autonoma de Madrid, and CIBERDEM, Madrid, Spain
| | - Luis Miguel Blanco-Colio
- Vascular Research Lab, IIS-Fundación Jiménez Díaz, Universidad Autonoma de Madrid, and CIBERCV, Spain
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175
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Hallett PJ, Engelender S, Isacson O. Lipid and immune abnormalities causing age-dependent neurodegeneration and Parkinson's disease. J Neuroinflammation 2019; 16:153. [PMID: 31331333 PMCID: PMC6647317 DOI: 10.1186/s12974-019-1532-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 06/25/2019] [Indexed: 12/31/2022] Open
Abstract
This article describes pathogenic concepts and factors, in particular glycolipid abnormalities, that create cell dysfunction and synaptic loss in neurodegenerative diseases. By phenocopying lysosomal storage disorders, such as Gaucher disease and related disorders, age- and dose-dependent changes in glycolipid cell metabolism can lead to Parkinson's disease and related dementias. Recent results show that perturbation of sphingolipid metabolism can precede or is a part of abnormal protein handling in both genetic and idiopathic Parkinson's disease and Lewy body dementia. In aging and genetic predisposition with lipid disturbance, α-synuclein's normal vesicular and synaptic role may be detrimentally shifted toward accommodating and binding such lipids. Specific neuronal glycolipid, protein, and vesicular interactions create potential pathophysiology that is amplified by astroglial and microglial immune mechanisms resulting in neurodegeneration. This perspective provides a new logic for therapeutic interventions that do not focus on protein aggregation, but rather provides a guide to the complex biology and the common sequence of events that lead to age-dependent neurodegenerative disorders.
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Affiliation(s)
- Penelope J Hallett
- Neuroregeneration Research Institute, McLean Hospital/Harvard Medical School, Boston, USA
| | - Simone Engelender
- Neuroregeneration Research Institute, McLean Hospital/Harvard Medical School, Boston, USA.,Present Address: Department of Biochemistry, Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 31096, Haifa, Israel
| | - Ole Isacson
- Neuroregeneration Research Institute, McLean Hospital/Harvard Medical School, Boston, USA.
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176
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Vogels T, Murgoci AN, Hromádka T. Intersection of pathological tau and microglia at the synapse. Acta Neuropathol Commun 2019; 7:109. [PMID: 31277708 PMCID: PMC6612163 DOI: 10.1186/s40478-019-0754-y] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/19/2019] [Indexed: 02/07/2023] Open
Abstract
Tauopathies are a heterogenous class of diseases characterized by cellular accumulation of aggregated tau and include diseases such as Alzheimer’s disease (AD), progressive supranuclear palsy and chronic traumatic encephalopathy. Tau pathology is strongly linked to neurodegeneration and clinical symptoms in tauopathy patients. Furthermore, synapse loss is an early pathological event in tauopathies and is the strongest correlate of cognitive decline. Tau pathology is additionally associated with chronic neuroinflammatory processes, such as reactive microglia, astrocytes, and increased levels of pro-inflammatory molecules (e.g. complement proteins, cytokines). Recent studies show that as the principal immune cells of the brain, microglia play a particularly important role in the initiation and progression of tau pathology and associated neurodegeneration. Furthermore, AD risk genes such as Triggering receptor expressed on myeloid cells 2 (TREM2) and Apolipoprotein E (APOE) are enriched in the innate immune system and modulate the neuroinflammatory response of microglia to tau pathology. Microglia can play an active role in synaptic dysfunction by abnormally phagocytosing synaptic compartments of neurons with tau pathology. Furthermore, microglia are involved in synaptic spreading of tau – a process which is thought to underlie the progressive nature of tau pathology propagation through the brain. Spreading of pathological tau is also the predominant target for tau-based immunotherapy. Active tau vaccines, therapeutic tau antibodies and other approaches targeting the immune system are actively explored as treatment options for AD and other tauopathies. This review describes the role of microglia in the pathobiology of tauopathies and the mechanism of action of potential therapeutics targeting the immune system in tauopathies.
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177
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Targeting Apolipoprotein E for Alzheimer's Disease: An Industry Perspective. Int J Mol Sci 2019; 20:ijms20092161. [PMID: 31052389 PMCID: PMC6539182 DOI: 10.3390/ijms20092161] [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: 03/24/2019] [Revised: 04/27/2019] [Accepted: 04/28/2019] [Indexed: 02/08/2023] Open
Abstract
Apolipoprotein E (apoE), a key lipid transport protein in the brain, is predominantly produced by astrocytes. Astrocytes are the most numerous cell type in the brain and are the main support network for neurons. They play a critical role in the synthesis and delivery of cholesterol in the brain. Humans have three common apoE isoforms, apoE2, apoE3 and apoE4, that show a strong genotype effect on the risk and age of onset for sporadic and late onset forms of Alzheimer’s disease (AD). Carriers of an ε4 allele have an increased risk of developing AD, while those with an ε2 allele are protected. Investigations into the contribution of apoE to the development of AD has yielded conflicting results and there is still much speculation about the role of this protein in disease. Here, we review the opposing hypotheses currently described in the literature and the approaches that have been considered for targeting apoE as a novel therapeutic strategy for AD. Additionally, we provide our perspective on the rationale for targeting apoE and the challenges that arise with respect to “drug-ability” of this target.
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178
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Hammond TR, Marsh SE, Stevens B. Immune Signaling in Neurodegeneration. Immunity 2019; 50:955-974. [PMID: 30995509 PMCID: PMC6822103 DOI: 10.1016/j.immuni.2019.03.016] [Citation(s) in RCA: 195] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/17/2019] [Accepted: 03/18/2019] [Indexed: 02/07/2023]
Abstract
Neurodegenerative diseases of the central nervous system progressively rob patients of their memory, motor function, and ability to perform daily tasks. Advances in genetics and animal models are beginning to unearth an unexpected role of the immune system in disease onset and pathogenesis; however, the role of cytokines, growth factors, and other immune signaling pathways in disease pathogenesis is still being examined. Here we review recent genetic risk and genome-wide association studies and emerging mechanisms for three key immune pathways implicated in disease, the growth factor TGF-β, the complement cascade, and the extracellular receptor TREM2. These immune signaling pathways are important under both healthy and neurodegenerative conditions, and recent work has highlighted new functional aspects of their signaling. Finally, we assess future directions for immune-related research in neurodegeneration and potential avenues for immune-related therapies.
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Affiliation(s)
- Timothy R Hammond
- Boston Children's Hospital, F.M. Kirby Neurobiology Center, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Samuel E Marsh
- Boston Children's Hospital, F.M. Kirby Neurobiology Center, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Beth Stevens
- Boston Children's Hospital, F.M. Kirby Neurobiology Center, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.
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179
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Mamazhakypov A, Schermuly RT, Schaefer L, Wygrecka M. Lipids - two sides of the same coin in lung fibrosis. Cell Signal 2019; 60:65-80. [PMID: 30998969 DOI: 10.1016/j.cellsig.2019.04.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/07/2019] [Accepted: 04/12/2019] [Indexed: 12/16/2022]
Abstract
Idiopathic pulmonary fibrosis (IPF) is characterized by progressive extracellular matrix deposition in the lung parenchyma leading to the destruction of lung structure, respiratory failure and premature death. Recent studies revealed that the pathogenesis of IPF is associated with alterations in the synthesis and the activity of lipids, lipid regulating proteins and cell membrane lipid transporters and receptors in different lung cells. Furthermore, deregulated lipid metabolism was found to contribute to the profibrotic phenotypes of lung fibroblasts and alveolar epithelial cells. Consequently, several pharmacological agents, targeting lipids, lipid mediators, and lipoprotein receptors, was successfully tested in the animal models of lung fibrosis and entered early phase clinical trials. In this review, we highlight new therapeutic options to counteract disturbed lipid hemostasis in the maladaptive lung remodeling.
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Affiliation(s)
- Argen Mamazhakypov
- Department of Internal Medicine, Universities of Giessen and Marburg Lung Center, Giessen, Germany.
| | - Ralph T Schermuly
- Department of Internal Medicine, Universities of Giessen and Marburg Lung Center, Giessen, Germany.
| | - Liliana Schaefer
- Goethe University School of Medicine, Frankfurt am Main, Germany.
| | - Malgorzata Wygrecka
- Department of Biochemistry, Universities of Giessen and Marburg Lung Center, Giessen, Germany.
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180
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Poor Oral Health and Its Neurological Consequences: Mechanisms of Porphyromonas gingivalis Involvement in Cognitive Dysfunction. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s40496-019-0212-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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