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Investigating a Curcumin-Loaded PLGA-PEG-PLGA Thermo-Sensitive Hydrogel for the Prevention of Alzheimer’s Disease. Antioxidants (Basel) 2022; 11:antiox11040727. [PMID: 35453412 PMCID: PMC9026862 DOI: 10.3390/antiox11040727] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/01/2022] [Accepted: 04/02/2022] [Indexed: 01/27/2023] Open
Abstract
In Alzheimer’s disease (AD), the most common cause of dementia, patients generally forget to take pills or skip medication due to side effects, affecting the treatment efficacy. In this study, we combined a poly(lactic-co-glycolic acid), (PLGA)-poly(ethylene glycol), and (PEG)-PLGA thermo-sensitive hydrogel with curcumin (PGC) to deliver an intramuscular injection that could continuously release curcumin and maintain it at a constant level in blood to prevent AD development or progression. We evaluated the drug release profile and cytotoxicity of PGC and its effects on AD pathology through in vitro and in vivo studies and on cognitive function through an aluminum-chloride-induced AD rat model. In the in vitro study, PGC exhibited a lack of cytotoxicity, excellent anti-inflammatory and antioxidant properties, and microglial modulation. In the Morris water maze test, the PGC injection-administered AD rats presented well-focused searching behavior with the shortest swimming path and longest retention times in the quadrant where the platform was initially located. Furthermore, PGC reduced amyloid-beta aggregation and deposition and significantly increased hippocampal activity. This study demonstrated that intramuscular PGC injection can effectively prevent AD development or progression in rats without inducing toxicity; therefore, this strategy could help overcome the present challenges in AD management in humans.
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2
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La Rosa F, Saresella M, Marventano I, Piancone F, Ripamonti E, Al-Daghri N, Bazzini C, Zoia CP, Conti E, Ferrarese C, Clerici M. Stavudine Reduces NLRP3 Inflammasome Activation and Modulates Amyloid-β Autophagy. J Alzheimers Dis 2020; 72:401-412. [PMID: 31594217 DOI: 10.3233/jad-181259] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Alzheimer's disease (AD) is associated with the accumulation of amyloid-β (Aβ) within senile plaques in the brain and neuroinflammation, possibly driven by the activation of the NLRP3 inflammasome. Nucleoside reverse transcriptase inhibitors (NRTI) hamper the NLRP3 inflammasome assembly. OBJECTIVE We utilized an in vitro model reproducing the Aβ-driven inflammation seen in AD to analyze whether stavudine (D4T), a prototypical NRTI, modulates Aβ-mediated inflammasome activation and the ability of macrophages to eliminate Aβ via phagocytosis and autophagy. METHODS THP-1-derived macrophages were stimulated in vitro with Aβ42 or with Aβ42 after LPS-priming in the presence/absence of D4T. NLRP3 and TREM2 expression was analyzed by RT-PCR; phagocytosis, as well as ASC-Speck formation, was analyzed by Amnis FlowSight Imaging; NLRP3-produced cytokines were quantified by ELISA and, finally, autophagy was analyzed by measuring p-ERK1/2, p-AKT, beclin, p70-S6Kinase, and Lamp by ELISA and western blot. RESULTS IL-1β, IL-18, and caspase-1 were increased whereas Aβ phagocytosis and TREM2 were reduced in LPS+Aβ42-stimulated cells. D4T reduced NLRP3 assembly as well as IL-18 and caspase-1 production, but did not affect IL-1β production and TREM2 expression. Notably, whereas D4T reduced Aβ phagocytosis, Aβ autophagy by macrophages was stimulated by D4T, as witnessed by the down-modulation of ERK1/2 and AKT phosphorylation and the upregulation of beclin, LAMP, and p70-S6K, their downstream targets. CONCLUSION In this in vitro model of AD, D4T reduces NLRP3 inflammasome-associated inflammation and stimulates Aβ autophagy by macrophages. It will be interesting to verify the possibly beneficial effects of D4T in the clinical scenario.
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Affiliation(s)
- Francesca La Rosa
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Marina Saresella
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | | | - Federica Piancone
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | | | - Nasser Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Chiara Bazzini
- Laboratory of Neurobiology, School of Medicine and Surgery, Monza, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Chiara Paola Zoia
- Laboratory of Neurobiology, School of Medicine and Surgery, Monza, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Elisa Conti
- Laboratory of Neurobiology, School of Medicine and Surgery, Monza, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Carlo Ferrarese
- Laboratory of Neurobiology, School of Medicine and Surgery, Monza, Italy.,Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy.,Department of Neuroscience, S. Gerardo Hospital, Monza, Italy
| | - Mario Clerici
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy.,Department of Physiopathology and Transplants, University of Milan, Milan, Italy
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3
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Toomey CE, Heywood W, Benson BC, Packham G, Mills K, Lashley T. Investigation of pathology, expression and proteomic profiles in human TREM2 variant postmortem brains with and without Alzheimer's disease. Brain Pathol 2020; 30:794-810. [PMID: 32267026 PMCID: PMC8018003 DOI: 10.1111/bpa.12842] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/11/2020] [Accepted: 03/26/2020] [Indexed: 12/17/2022] Open
Abstract
Triggering receptor expressed on myeloid cells 2 TREM2 was identified as a risk factor for late onset Alzheimer’s disease (AD). Here we compared TREM2 cases with a variant (TREM2+) and cases without a TREM2 variant (TREM2−), considering pathological burden, inflammatory response and altered canonical pathways and biochemical functions between the cohorts. We hypothesised that TREM2+ cases would have a loss of function, indicating an altered inflammatory profile compared to TREM2− cases. Immunohistochemistry was performed using antibodies against Aβ, tau and microglia markers in TREM2+ cases, with and without AD, which were compared to sporadic TREM2− AD, familial AD and neurologically normal control cases. Aβ and tau load were measured along with the composition of Aβ plaques, in addition to microglial load and circularity. Expression and proteomic profiles were determined from the frontal cortex of selected cases. TREM2+ control cases had no Aβ or tau deposition. No differences in the amount of Aβ or tau, or the composition of Aβ plaques were observed between TREM2+ and TREM2− SAD cases. There were no differences in microglial load observed between disease groups. However, the TREM2+ SAD cases showed more amoeboid microglia than the TREM2− SAD cases, although no differences in the spatial relationship of microglia and Aβ plaques were identified. Visualisation of the canonical pathways and biological functions showed differences between the disease groups and the normal controls, clearly showing a number of pathways upregulated in TREM2+ SAD, TREM2− SAD and FAD groups whilst, the TREM2+ controls cases showed a downregulation of the majority of the represented pathways. These findings suggest that the TREM2+ control group, although carrying the TREM2+ variant, have no pathological hallmarks of AD, have altered microglial and expression profiles compared to the TREM2+ SAD cases. This indicates that other unknown factors may initiate the onset of AD, with TREM2 influencing the microglial involvement in disease pathogenesis.
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Affiliation(s)
- Christina E Toomey
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, London, UK.,Department of Neurodegenerative diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Wendy Heywood
- Centre for Translational Omics, Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Bridget C Benson
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, London, UK
| | - Georgia Packham
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, London, UK
| | - Kevin Mills
- Centre for Translational Omics, Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Tammaryn Lashley
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, London, UK.,Department of Neurodegenerative diseases, UCL Queen Square Institute of Neurology, London, UK
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4
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Morris G, Puri BK, Maes M, Olive L, Berk M, Carvalho AF. The role of microglia in neuroprogressive disorders: mechanisms and possible neurotherapeutic effects of induced ketosis. Prog Neuropsychopharmacol Biol Psychiatry 2020; 99:109858. [PMID: 31923453 DOI: 10.1016/j.pnpbp.2020.109858] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 01/03/2020] [Accepted: 01/05/2020] [Indexed: 12/23/2022]
Abstract
A comprehensive review of molecular mechanisms involved in the promotion and maintenance of distinct microglia phenotypes is provided. The acquisition and perpetuation of predominantly pro-inflammatory microglial phenotypes have been implicated in the pathophysiology of several neuroprogressive diseases and is associated with reduced ATP production via oxidative phosphorylation, increased ATP generation by glycolysis, elevated oxidative and nitrosative stress and other metabolic, inflammatory and hormonal insults. Microglia can also adopt a predominantly anti-inflammatory phenotypes with neuroprotective properties. Strategies that promote and maintain a predominantly anti-inflammatory phenotype may hold promise as novel therapeutic opportunities for neuroprogressive illness. Induced ketosis may promote a transition towards predominantly anti-inflammatory microglial states/phenotypes by several mechanisms, including inhibition of glycolysis and increased NAD+ production; engagement of microglial GPR109A receptors; histone deacetylase inhibition; and elevated n-3 polyunsaturated fatty acids levels. Since microglia activation can now be assessed in vivo, these data provide a clear rationale for the design of transdiagnostic randomized controlled trials of the ketogenic diet and other ketosis-inducing strategies for neuroprogressive diseases, which may also provide mechanistic insights through the assessment of "target engagement".
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Affiliation(s)
- Gerwyn Morris
- Deakin University, IMPACT Strategic Research Centre, Barwon Health, School of Medicine, Geelong, Victoria, Australia
| | | | - Michael Maes
- Deakin University, IMPACT Strategic Research Centre, Barwon Health, School of Medicine, Geelong, Victoria, Australia
| | - Lisa Olive
- Deakin University, IMPACT Strategic Research Centre, Barwon Health, School of Medicine, Geelong, Victoria, Australia
| | - Michael Berk
- Deakin University, IMPACT Strategic Research Centre, Barwon Health, School of Medicine, Geelong, Victoria, Australia; Deakin University, CMMR Strategic Research Centre, School of Medicine, Geelong, Victoria, Australia; Orygen, The National Centre of Excellence in Youth Mental Health, The Department of Psychiatry and the Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Andre F Carvalho
- Deakin University, IMPACT Strategic Research Centre, Barwon Health, School of Medicine, Geelong, Victoria, Australia; Department of Psychiatry, University of Toronto, Toronto, ON, Canada; Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada.
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5
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Imbalance of Microglial TLR4/TREM2 in LPS-Treated APP/PS1 Transgenic Mice: A Potential Link Between Alzheimer's Disease and Systemic Inflammation. Neurochem Res 2019; 44:1138-1151. [PMID: 30756214 DOI: 10.1007/s11064-019-02748-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 02/01/2019] [Accepted: 02/01/2019] [Indexed: 02/07/2023]
Abstract
Clinically, superimposed systemic inflammation generally has significant deleterious effects on the Alzheimer's disease (AD) progression. However, the related molecular mechanisms remain poorly understood. Microglial toll-like receptor 4 (TLR4) and triggering receptor expressed on myeloid cells 2 (TREM2) are two key regulators of inflammation that may play an essential role in this complex pathophysiological process. In this study, intraperitoneal injection of lipopolysaccharide (LPS) into APP/PS1 transgenic AD model was used to mimic systemic inflammation in the development of AD. Initial results from the cortex showed that compared with wild-type mice, APP/PS1 mice exhibited elevated gene and protein expression levels of both TLR4 and TREM2 with different degree. Interestingly, after LPS treatment, TLR4 expression was persistently up-regulated, while TREM2 expression was significantly down-regulated in APP/PS1 mice, suggesting that the negative regulatory effect of TREM2 on inflammation might be suppressed by LPS-induced hyperactive TLR4. This imbalance of TLR4/TREM2 contributed to microglial over-activation, followed by increased neuronal apoptosis in the cortex of APP/PS1 mice; these changes did not alter the expression level of Aβ1-42. Similar alterations were observed in our in vitro experiment with β-amyloid1-42 (Aβ1-42)-treated N9 microglia. Further, Morris water maze (MWM) testing data indicated that LPS administration acutely aggravated cognitive impairment in APP/PS1 mice, suggesting that the addition of systemic inflammation can potentially accelerate the progression of AD. Collectively, we conclude that an imbalance of TLR4/TREM2 may be a potential link between AD and systemic inflammation. TREM2 can serve as a potential therapeutic target for treating systemic inflammation in AD progression.
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6
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Chun H, Marriott I, Lee CJ, Cho H. Elucidating the Interactive Roles of Glia in Alzheimer's Disease Using Established and Newly Developed Experimental Models. Front Neurol 2018; 9:797. [PMID: 30319529 PMCID: PMC6168676 DOI: 10.3389/fneur.2018.00797] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 09/04/2018] [Indexed: 12/21/2022] Open
Abstract
Alzheimer's disease (AD) is an irreversible neurodegenerative illness and the exact etiology of the disease remains unknown. It is characterized by long preclinical and prodromal phases with pathological features including an accumulation of amyloid-beta (Aβ) peptides into extracellular Aβ plaques in the brain parenchyma and the formation of intracellular neurofibrillary tangles (NFTs) within neurons as a result of abnormal phosphorylation of microtubule-associated tau proteins. In addition, prominent activation of innate immune cells is also observed and/or followed by marked neuroinflammation. While such neuroinflammatory responses may function in a neuroprotective manner by clearing neurotoxic factors, they can also be neurotoxic by contributing to neurodegeneration via elevated levels of proinflammatory mediators and oxidative stress, and altered levels of neurotransmitters, that underlie pathological symptoms including synaptic and cognitive impairment, neuronal death, reduced memory, and neocortex and hippocampus malfunctions. Glial cells, particularly activated microglia and reactive astrocytes, appear to play critical and interactive roles in such dichotomous responses. Accumulating evidences clearly point to their critical involvement in the prevention, initiation, and progression, of neurodegenerative diseases, including AD. Here, we review recent findings on the roles of astrocyte-microglial interactions in neurodegeneration in the context of AD and discuss newly developed in vitro and in vivo experimental models that will enable more detailed analysis of glial interplay. An increased understanding of the roles of glia and the development of new exploratory tools are likely to be crucial for the development of new interventions for early stage AD prevention and cures.
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Affiliation(s)
- Heejung Chun
- Center for Glia-Neuron Interaction, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea
| | - Ian Marriott
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, United States
| | - C Justin Lee
- Center for Glia-Neuron Interaction, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea.,Bio-Med, University of Science and Technology, Daejeon, South Korea
| | - Hansang Cho
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, United States.,Department of Mechanical Engineering and Engineering Science, University of North Carolina at Charlotte, Charlotte, NC, United States.,Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, NC, United States.,The Nanoscale Science Program, University of North Carolina at Charlotte, Charlotte, NC, United States
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7
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Hu LY, Zhou Y, Cui WQ, Hu XM, Du LX, Mi WL, Chu YX, Wu GC, Wang YQ, Mao-Ying QL. Triggering receptor expressed on myeloid cells 2 (TREM2) dependent microglial activation promotes cisplatin-induced peripheral neuropathy in mice. Brain Behav Immun 2018; 68:132-145. [PMID: 29051087 DOI: 10.1016/j.bbi.2017.10.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/04/2017] [Accepted: 10/14/2017] [Indexed: 12/30/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a common adverse side effect of many antineoplastic agents. Patients treated with chemotherapy often report pain and paresthesias in a "glove-and-stocking" distribution. Diverse mechanisms contribute to the development and maintenance of CIPN. However, the role of spinal microglia in CIPN is not completely understood. In this study, cisplatin-treated mice displayed persistent mechanical allodynia, sensory deficits and decreased density of intraepidermal nerve fibers (IENFs). In the spinal cord, activation of microglia, but not astrocyte, was persistently observed until week five after the first cisplatin injection. Additionally, mRNA levels of inflammation related molecules including IL-1β, IL-6, tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS) and CD16, were increased after cisplatin treatment. Intraperitoneal (i.p.) or intrathecal (i.t.) injection with minocycline both alleviated cisplatin-induced mechanical allodynia and sensory deficits, and prevented IENFs loss. Furthermore, cisplatin enhanced triggering receptor expressed on myeloid cells 2 (TREM2) /DNAX-activating protein of 12 kDa (DAP12) signaling in the spinal cord microglia. The blockage of TREM2 by i.t. injecting anti-TREM2 neutralizing antibody significantly attenuated cisplatin-induced mechanical allodynia, sensory deficits and IENFs loss. Meanwhile, anti-TREM2 neutralizing antibody prominently suppressed the spinal IL-6, TNF-α, iNOS and CD16 mRNA level, but it dramatically up-regulated the anti-inflammatory cytokines IL-4 and IL-10. The data demonstrated that cisplatin triggered persistent activation of spinal cord microglia through strengthening TREM2/DAP12 signaling, which further resulted in CIPN. Functional blockage of TREM2 or inhibition of microglia both benefited for cisplatin-induced peripheral neuropathy. Microglial TREM2/DAP12 may serve as a potential target for CIPN intervention.
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Affiliation(s)
- Lang-Yue Hu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Yang Zhou
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Wen-Qiang Cui
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Xue-Ming Hu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Li-Xia Du
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Wen-Li Mi
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Yu-Xia Chu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Gen-Cheng Wu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Yan-Qing Wang
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China
| | - Qi-Liang Mao-Ying
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Science, Institutes of Brain Science, Collaborative Innovation Center for Brain Science, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, People's Republic of China.
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8
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Morris G, Puri BK, Frye RE. The putative role of environmental aluminium in the development of chronic neuropathology in adults and children. How strong is the evidence and what could be the mechanisms involved? Metab Brain Dis 2017; 32:1335-1355. [PMID: 28752219 PMCID: PMC5596046 DOI: 10.1007/s11011-017-0077-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 07/19/2017] [Indexed: 02/06/2023]
Abstract
The conceptualisation of autistic spectrum disorder and Alzheimer's disease has undergone something of a paradigm shift in recent years and rather than being viewed as single illnesses with a unitary pathogenesis and pathophysiology they are increasingly considered to be heterogeneous syndromes with a complex multifactorial aetiopathogenesis, involving a highly complex and diverse combination of genetic, epigenetic and environmental factors. One such environmental factor implicated as a potential cause in both syndromes is aluminium, as an element or as part of a salt, received, for example, in oral form or as an adjuvant. Such administration has the potential to induce pathology via several routes such as provoking dysfunction and/or activation of glial cells which play an indispensable role in the regulation of central nervous system homeostasis and neurodevelopment. Other routes include the generation of oxidative stress, depletion of reduced glutathione, direct and indirect reductions in mitochondrial performance and integrity, and increasing the production of proinflammatory cytokines in both the brain and peripherally. The mechanisms whereby environmental aluminium could contribute to the development of the highly specific pattern of neuropathology seen in Alzheimer's disease are described. Also detailed are several mechanisms whereby significant quantities of aluminium introduced via immunisation could produce chronic neuropathology in genetically susceptible children. Accordingly, it is recommended that the use of aluminium salts in immunisations should be discontinued and that adults should take steps to minimise their exposure to environmental aluminium.
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Affiliation(s)
- Gerwyn Morris
- Tir Na Nog, Bryn Road seaside 87, Llanelli, Wales, SA15 2LW, UK
| | - Basant K Puri
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, England, W12 0HS, UK.
| | - Richard E Frye
- College of Medicine, Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, Little Rock, AR, 72202, USA
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9
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Perez SE, Nadeem M, He B, Miguel JC, Malek-Ahmadi MH, Chen K, Mufson EJ. Neocortical and hippocampal TREM2 protein levels during the progression of Alzheimer's disease. Neurobiol Aging 2017; 54:133-143. [PMID: 28365005 PMCID: PMC6344038 DOI: 10.1016/j.neurobiolaging.2017.02.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/14/2017] [Accepted: 02/16/2017] [Indexed: 01/09/2023]
Abstract
Heterozygous triggering receptor expressed on myeloid cells (TREM2) mutations are an Alzheimer's disease (AD) risk factor. Nonmutated TREM2 dysregulation occurs in AD brain. Whether TREM2 is altered in prodromal AD remains unknown. Western blotting was used to determine levels of TREM2 (∼25 kDa) and Iba1 in the frontal cortex and TREM2 in the hippocampus from people who died with an ante-mortem clinical diagnosis of non- and mild-cognitive impairment, mild/moderate AD, and severe AD (sAD). Immunohistochemistry defined the relationship between amyloid and Iba1 profiles. Polymerase chain reaction analysis revealed that all subjects did not carry the most common R47H TREM2 variant. TREM2 was significantly upregulated in sAD frontal cortex but stable in hippocampus. Frontal TREM2 mRNA and protein level patterns were similar but not significantly different. Iba1 immunopositive microglia counts increased significantly in frontal cortex containing plaques in sAD. TREM2 and Iba1 levels were not associated with plaques, tangles, neuropathological criteria, or cognitive performance. Frontal cortex TREM2 upregulation is a late event and may not play a major role early in the pathogenesis of the disease.
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Affiliation(s)
- Sylvia E Perez
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Muhammad Nadeem
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Bin He
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Jennifer C Miguel
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA
| | | | - Kewei Chen
- Banner Alzheimer's Institute, Phoenix, AZ, USA
| | - Elliott J Mufson
- Departments of Neurobiology and Neurology, Alzheimer's disease Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, USA.
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10
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Millan MJ. Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review. Prog Neurobiol 2017; 156:1-68. [PMID: 28322921 DOI: 10.1016/j.pneurobio.2017.03.004] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/09/2017] [Accepted: 03/09/2017] [Indexed: 02/06/2023]
Abstract
The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.
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Affiliation(s)
- Mark J Millan
- Centre for Therapeutic Innovation in Neuropsychiatry, institut de recherche Servier, 125 chemin de ronde, 78290 Croissy sur Seine, France.
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11
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Möhle L, Israel N, Paarmann K, Krohn M, Pietkiewicz S, Müller A, Lavrik IN, Buguliskis JS, Schott BH, Schlüter D, Gundelfinger ED, Montag D, Seifert U, Pahnke J, Dunay IR. Chronic Toxoplasma gondii infection enhances β-amyloid phagocytosis and clearance by recruited monocytes. Acta Neuropathol Commun 2016; 4:25. [PMID: 26984535 PMCID: PMC4793516 DOI: 10.1186/s40478-016-0293-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 02/19/2016] [Indexed: 01/02/2023] Open
Abstract
INTRODUCTION Alzheimer's disease (AD) is associated with the accumulation of β-amyloid (Aβ) as senile plaques in the brain, thus leading to neurodegeneration and cognitive impairment. Plaque formation depends not merely on the amount of generated Aβ peptides, but more importantly on their effective removal. Chronic infections with neurotropic pathogens, most prominently the parasite Toxoplasma (T.) gondii, are frequent in the elderly, and it has been suggested that the resulting neuroinflammation may influence the course of AD. In the present study, we investigated how chronic T. gondii infection and resulting neuroinflammation affect plaque deposition and removal in a mouse model of AD. RESULTS Chronic infection with T. gondii was associated with reduced Aβ and plaque load in 5xFAD mice. Upon infection, myeloid-derived CCR2(hi) Ly6C(hi) monocytes, CCR2(+) Ly6C(int), and CCR2(+) Ly6C(low) mononuclear cells were recruited to the brain of mice. Compared to microglia, these recruited mononuclear cells showed highly increased phagocytic capacity of Aβ ex vivo. The F4/80(+) Ly6C(low) macrophages expressed high levels of Triggering Receptor Expressed on Myeloid cells 2 (TREM2), CD36, and Scavenger Receptor A1 (SCARA1), indicating phagocytic activity. Importantly, selective ablation of CCR2(+) Ly6C(hi) monocytes resulted in an increased amount of Aβ in infected mice. Elevated insulin-degrading enzyme (IDE), matrix metalloproteinase 9 (MMP9), as well as immunoproteasome subunits β1i/LMP2, β2i/MECL-1, and β5i/LMP7 mRNA levels in the infected brains indicated increased proteolytic Aβ degradation. Particularly, LMP7 was highly expressed by the recruited mononuclear cells in the brain, suggesting a novel mechanism of Aβ clearance. CONCLUSIONS Our results indicate that chronic Toxoplasma infection ameliorates β-amyloidosis in a murine model of AD by activation of the immune system, specifically by recruitment of Ly6C(hi) monocytes and by enhancement of phagocytosis and degradation of soluble Aβ. Our findings provide evidence for a modulatory role of inflammation-induced Aβ phagocytosis and degradation by newly recruited peripheral immune cells in the pathophysiology of AD.
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Affiliation(s)
- Luisa Möhle
- Institute for Medical Microbiology and Hospital Hygiene, University of Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Nicole Israel
- Institute for Molecular and Clinical Immunology, University of Magdeburg, Magdeburg, Germany
| | - Kristin Paarmann
- Department of Pathology (PAT), Translational Neurodegeneration Research and Neuropathology Lab, University of Oslo (UiO) and Oslo University Hospital (OUS), Oslo, Norway
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Neurogenetics, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Markus Krohn
- Department of Pathology (PAT), Translational Neurodegeneration Research and Neuropathology Lab, University of Oslo (UiO) and Oslo University Hospital (OUS), Oslo, Norway
| | - Sabine Pietkiewicz
- Department of Translational Inflammation Research, Institute of Experimental Internal Medicine, University of Magdeburg, Magdeburg, Germany
| | - Andreas Müller
- Institute for Molecular and Clinical Immunology, University of Magdeburg, Magdeburg, Germany
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Inna N Lavrik
- Department of Translational Inflammation Research, Institute of Experimental Internal Medicine, University of Magdeburg, Magdeburg, Germany
| | | | - Björn H Schott
- Center for Behavioral Brain Sciences (CBBS), University of Magdeburg, Magdeburg, Germany
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Department of Psychiatry and Psychotherapy, Campus Mitte, Charité Universitätsmedizin, Berlin, Germany
| | - Dirk Schlüter
- Institute for Medical Microbiology and Hospital Hygiene, University of Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), University of Magdeburg, Magdeburg, Germany
| | - Eckart D Gundelfinger
- Center for Behavioral Brain Sciences (CBBS), University of Magdeburg, Magdeburg, Germany
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Medical Faculty, University of Magdeburg, Magdeburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Dirk Montag
- Neurogenetics, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Ulrike Seifert
- Institute for Molecular and Clinical Immunology, University of Magdeburg, Magdeburg, Germany
| | - Jens Pahnke
- Department of Pathology (PAT), Translational Neurodegeneration Research and Neuropathology Lab, University of Oslo (UiO) and Oslo University Hospital (OUS), Oslo, Norway
- University of Lübeck (UzL), LIED, Lübeck, Germany
- Leibniz Institute of Plant Biochemistry (IPB), Halle, Germany
| | - Ildiko Rita Dunay
- Institute for Medical Microbiology and Hospital Hygiene, University of Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany.
- Center for Behavioral Brain Sciences (CBBS), University of Magdeburg, Magdeburg, Germany.
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microRNA-34a-Mediated Down-Regulation of the Microglial-Enriched Triggering Receptor and Phagocytosis-Sensor TREM2 in Age-Related Macular Degeneration. PLoS One 2016; 11:e0150211. [PMID: 26949937 PMCID: PMC4780721 DOI: 10.1371/journal.pone.0150211] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 02/10/2016] [Indexed: 12/17/2022] Open
Abstract
The aggregation of Aβ42-peptides and the formation of drusen in age-related macular degeneration (AMD) are due in part to the inability of homeostatic phagocytic mechanisms to clear self-aggregating Aβ42-peptides from the extracellular space. The triggering receptor expressed in myeloid/microglial cells-2 (TREM2), a trans-membrane-spanning, sensor-receptor of the immune-globulin/lectin-like gene superfamily is a critical component of Aβ42-peptide clearance. Here we report a significant deficit in TREM2 in AMD retina and in cytokine- or oxidatively-stressed microglial (MG) cells. RT-PCR, miRNA-array, LED-Northern and Western blot studies indicated up-regulation of a microglial-enriched NF-кB-sensitive miRNA-34a coupled to a down-regulation of TREM2 in the same samples. Bioinformatics/transfection-luciferase reporter assays indicated that miRNA-34a targets the 299 nucleotide TREM2-mRNA-3'UTR, resulting in TREM2 down-regulation. C8B4-microglial cells challenged with Aβ42 were able to phagocytose these peptides, while miRNA-34a down-regulated both TREM2 and the ability of microglial-cells to phagocytose. Treatment of TNFα-stressed MG cells with phenyl-butyl nitrone (PBN), caffeic-acid phenethyl ester (CAPE), the NF-kB - [corrected] inhibitor/resveratrol analog CAY10512 or curcumin abrogated these responses. Incubation of anti-miRNA-34a (AM-34a) normalized miRNA-34a abundance and restored TREM2 back to homeostatic levels. These data support five novel observations: (i) that a ROS- and NF-kB - [corrected] sensitive, miRNA-34a-mediated modulation of TREM2 may in part regulate the phagocytic response; (ii) that gene products encoded on two different chromosomes (miRNA-34a at chr1q36.22 and TREM2 at chr6p21.1) orchestrate a phagocytic-Aβ42-peptide clearance-system; (iii) that this NF-kB-mediated-miRNA-34a-TREM2 mechanism is inducible from outside of the cell; (iv) that when operating normally, this pathway can clear Aβ42 peptide monomers from the extracellular medium; and (v) that anti-NF-kB and/or anti-miRNA (AM)-based therapeutic strategies may be useful against deficits in TREM-2 receptor-based-sensing and -phagocytic signaling that promote pathogenic amyloidogenesis.
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MicroRNA (miRNA) Signaling in the Human CNS in Sporadic Alzheimer's Disease (AD)-Novel and Unique Pathological Features. Int J Mol Sci 2015; 16:30105-16. [PMID: 26694372 PMCID: PMC4691165 DOI: 10.3390/ijms161226223] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 12/12/2015] [Accepted: 12/15/2015] [Indexed: 02/07/2023] Open
Abstract
Of the approximately ~2.65 × 103 mature microRNAs (miRNAs) so far identified in Homo sapiens, only a surprisingly small but select subset—about 35–40—are highly abundant in the human central nervous system (CNS). This fact alone underscores the extremely high selection pressure for the human CNS to utilize only specific ribonucleotide sequences contained within these single-stranded non-coding RNAs (ncRNAs) for productive miRNA–mRNA interactions and the down-regulation of gene expression. In this article we will: (i) consolidate some of our still evolving ideas concerning the role of miRNAs in the CNS in normal aging and in health, and in sporadic Alzheimer’s disease (AD) and related forms of chronic neurodegeneration; and (ii) highlight certain aspects of the most current work in this research field, with particular emphasis on the findings from our lab of a small pathogenic family of six inducible, pro-inflammatory, NF-κB-regulated miRNAs including miRNA-7, miRNA-9, miRNA-34a, miRNA-125b, miRNA-146a and miRNA-155. This group of six CNS-abundant miRNAs significantly up-regulated in sporadic AD are emerging as what appear to be key mechanistic contributors to the sporadic AD process and can explain much of the neuropathology of this common, age-related inflammatory neurodegeneration of the human CNS.
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Zhao Y, Bhattacharjee S, Jones BM, Hill JM, Clement C, Sambamurti K, Dua P, Lukiw WJ. Beta-Amyloid Precursor Protein (βAPP) Processing in Alzheimer's Disease (AD) and Age-Related Macular Degeneration (AMD). Mol Neurobiol 2015; 52:533-44. [PMID: 25204496 PMCID: PMC4362880 DOI: 10.1007/s12035-014-8886-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/27/2014] [Indexed: 01/18/2023]
Abstract
Amyloid is a generic term for insoluble, often intensely hydrophobic, fibrous protein aggregates that arise from inappropriately folded versions of naturally-occurring polypeptides. The abnormal generation and accumulation of amyloid, often referred to as amyloidogenesis, has been associated with the immune and pro-inflammatory pathology of several progressive age-related diseases of the human central nervous system (CNS) including Alzheimer's disease (AD) and age-related macular degeneration (AMD). This 'research perspective' paper reviews some of the research history, biophysics, molecular-genetics and environmental factors concerning the contribution of amyloid beta (Aβ) peptides, derived from beta-amyloid precursor protein (βAPP), to AD and AMD that suggests an extensive similarity in immune and inflammatory degenerative mechanisms between these two CNS diseases.
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Affiliation(s)
- Yuhai Zhao
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
| | - Surjyadipta Bhattacharjee
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
| | - Brandon M. Jones
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
| | - James M. Hill
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Ophthalmology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Microbiology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Pharmacology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Neurology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
| | - Christian Clement
- Department of Natural Sciences, Infectious Diseases, Experimental Therapeutics and Human Toxicology Lab, Southern University at New Orleans, New Orleans, LA 70126 USA
| | | | - Prerna Dua
- Department of Health Information Management, Louisiana State University, Ruston, LA 71272 USA
| | - Walter J. Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Ophthalmology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Microbiology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112 USA
- Department of Natural Sciences, Infectious Diseases, Experimental Therapeutics and Human Toxicology Lab, Southern University at New Orleans, New Orleans, LA 70126 USA
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15
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Zhao Y, Lukiw WJ. Microbiome-generated amyloid and potential impact on amyloidogenesis in Alzheimer's disease (AD). JOURNAL OF NATURE AND SCIENCE 2015; 1:e138. [PMID: 26097896 PMCID: PMC4469284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
According to the 'amyloid cascade hypothesis of Alzheimer's disease' first proposed about 16 years ago, the accumulation of Aβ peptides in the human central nervous system (CNS) is the primary influence driving Alzheimer's disease (AD) pathogenesis, and Aβ peptide accretion is the result of an imbalance between Aβ peptide production and clearance. In the last 18 months multiple laboratories have reported two particularly important observations: (i) that because the microbes of the human microbiome naturally secrete large amounts of amyloid, lipopolysaccharides (LPS) and other related pro-inflammatory pathogenic signals, these may contribute to both the systemic and CNS amyloid burden in aging humans; and (ii) that the clearance of Aβ peptides appears to be intrinsically impaired by deficits in the microglial plasma-membrane enriched triggering receptor expressed in microglial/myeloid-2 cells (TREM2). This brief general commentary-perspective paper: (i) will highlight some of these very recent findings on microbiome-secreted amyloids and LPS and the potential contribution of these microbial-derived pro-inflammatory and neurotoxic exudates to age-related inflammatory and AD-type neurodegeneration in the host; and (ii) will discuss the contribution of a defective microglial-based TREM2 transmembrane sensor-receptor system to amyloidogenesis in AD that is in contrast to the normal, homeostatic clearance of Aβ peptides from the human CNS.
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Affiliation(s)
- Yuhai Zhao
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans, LA 70112, USA
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans, LA 70112, USA
| | - Walter J. Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans, LA 70112, USA
- Department of Ophthalmology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans, LA 70112, USA
- Department of Neurology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans, LA 70112, USA
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Zhao Y, Dua P, Lukiw WJ. Microbial Sources of Amyloid and Relevance to Amyloidogenesis and Alzheimer's Disease (AD). JOURNAL OF ALZHEIMER'S DISEASE & PARKINSONISM 2015; 5:177. [PMID: 25977840 PMCID: PMC4428612 DOI: 10.4172/2161-0460.1000177] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Since the inception of the human microbiome project (HMP) by the US National Institutes of Health (NIH) in 2007 there has been a keen resurgence in our recognition of the human microbiome and its contribution to development, immunity, neurophysiology, metabolic and nutritive support to central nervous system (CNS) health and disease. What is not generally appreciated is that (i) the ~1014 microbial cells that comprise the human microbiome outnumber human host cells by approximately one hundred-to-one; (ii) together the microbial genes of the microbiome outnumber human host genes by about one hundred-and-fifty to one; (iii) collectively these microbes constitute the largest 'diffuse organ system' in the human body, more metabolically active than the liver; strongly influencing host nutritive-, innate-immune, neuroinflammatory-, neuromodulatory- and neurotransmission-functions; and (iv) that these microbes actively secrete highly complex, immunogenic mixtures of lipopolysaccharide (LPS) and amyloid from their outer membranes into their immediate environment. While secreted LPS and amyloids are generally quite soluble as monomers over time they form into highly insoluble fibrous protein aggregates that are implicated in the progressive degenerative neuropathology of several common, age-related disorders of the human CNS including Alzheimer's disease (AD). This general commentary-perspective paper will highlight some recent findings on microbial-derived secreted LPS and amyloids and the potential contribution of these neurotoxic and proinflammatory microbial exudates to age-related inflammatory amyloidogenesis and neurodegeneration, with specific reference to AD wherever possible.
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Affiliation(s)
- Y Zhao
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans LA 70112 USA ; Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans LA 70112 USA
| | - P Dua
- Department of Health Information Management, Louisiana State University Ruston LA 71270 USA
| | - W J Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans LA 70112 USA ; Department of Ophthalmology, Louisiana State University Health Sciences Center, 533 Bolivar Street, New Orleans LA 70112 USA ; Department of Neurology, Louisiana State University Health Sciences Center, 1542 Tulane Avenue, New Orleans LA 70112 USA
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Hill JM, Lukiw WJ. Microbial-generated amyloids and Alzheimer's disease (AD). Front Aging Neurosci 2015; 7:9. [PMID: 25713531 PMCID: PMC4322713 DOI: 10.3389/fnagi.2015.00009] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 01/21/2015] [Indexed: 01/27/2023] Open
Affiliation(s)
- James M Hill
- Louisiana State University Neuroscience Center, Louisiana State University Health Sciences Center New Orleans, LA, USA ; Departments of Ophthalmology, Louisiana State University Health Sciences Center New Orleans, LA, USA ; Microbiology, Louisiana State University Health Sciences Center New Orleans, LA, USA ; Pharmacology, Louisiana State University Health Sciences Center New Orleans, LA, USA
| | - Walter J Lukiw
- Louisiana State University Neuroscience Center, Louisiana State University Health Sciences Center New Orleans, LA, USA ; Departments of Ophthalmology, Louisiana State University Health Sciences Center New Orleans, LA, USA ; Neurology, Louisiana State University Health Sciences Center New Orleans, LA, USA
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Li X, Montine KS, Keene CD, Montine TJ. Different mechanisms of apolipoprotein E isoform-dependent modulation of prostaglandin E2 production and triggering receptor expressed on myeloid cells 2 (TREM2) expression after innate immune activation of microglia. FASEB J 2015; 29:1754-62. [PMID: 25593125 DOI: 10.1096/fj.14-262683] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/15/2014] [Indexed: 01/14/2023]
Abstract
Several lines of evidence support immune response in brain as a mechanism of injury in Alzheimer disease (AD). Moreover, immune activation is heightened in apolipoprotein E (APOE) ε4 carriers; inhibitors of prostaglandin (PG) synthesis show a partially protective effect on AD risk from APOE ε4; and genetic variants in triggering receptor expressed on myeloid cells 2 (TREM2) are a rare but potent risk for AD. We tested the hypothesis that APOE ε4 inheritance modulates both the PGE2 pathway and TREM2 expression using primary murine microglia from targeted replacement (TR) APOE3/3 and APOE4/4 mice. Microglial cyclooxygenase-2, microsomal PGE synthase, and PGE2 expression were increased 2- to 25-fold in both genotypes by TLR activators; however, this induction was significantly (P < 0.01) greater in TR APOE4/4 microglia with TLR3 and TLR4 activators. Microglial TREM2 expression was reduced approximately 85% by all TLR activators; this reduction was approximately one-third greater in microglia from TR APOE4/4 mice. Importantly, both receptor-associated protein and a nuclear factor κ-light-chain-enhancer inhibitor blocked TR APOE4/4-dependent effects on the PGE2 pathway but not on TREM2 expression. These data demonstrate complementary, but mechanistically distinct, regulation of pro- and anti-inflammatory mediators in TR APOE4/4 murine microglia that yields a more proinflammatory state than with TR APOE3/3.
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Affiliation(s)
- Xianwu Li
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Kathleen S Montine
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Thomas J Montine
- Department of Pathology, University of Washington, Seattle, Washington, USA
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Latypova X, Martin L. 2015: which new directions for Alzheimer's disease? Front Cell Neurosci 2014; 8:417. [PMID: 25538567 PMCID: PMC4260501 DOI: 10.3389/fncel.2014.00417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 11/17/2014] [Indexed: 01/06/2023] Open
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Zhao Y, Hill JM, Bhattacharjee S, Percy ME, Pogue AID, Lukiw WJ. Aluminum-induced amyloidogenesis and impairment in the clearance of amyloid peptides from the central nervous system in Alzheimer's disease. Front Neurol 2014; 5:167. [PMID: 25250012 PMCID: PMC4155793 DOI: 10.3389/fneur.2014.00167] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/20/2014] [Indexed: 12/03/2022] Open
Affiliation(s)
- Yuhai Zhao
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA ; Department of Ophthalmology, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA
| | - James M Hill
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA ; Department of Ophthalmology, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA ; Department of Microbiology, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA
| | - Surjyadipta Bhattacharjee
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA
| | - Maire E Percy
- Department of Physiology, University of Toronto , Toronto, ON , Canada ; Department of Obstetrics and Gynaecology, University of Toronto , Toronto, ON , Canada ; Neurogenetics Laboratory, Surrey Place Centre , Toronto, ON , Canada
| | | | - Walter J Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA ; Department of Ophthalmology, Louisiana State University Health Sciences Center, Louisiana State University , New Orleans, LA , USA ; Alchem Biotech , Toronto, ON , Canada ; Department of Neurology, Louisiana State University Health Sciences Center , New Orleans, LA , USA
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Bhattacharjee S, Zhao Y, Lukiw WJ. Deficits in the miRNA-34a-regulated endogenous TREM2 phagocytosis sensor-receptor in Alzheimer's disease (AD); an update. Front Aging Neurosci 2014; 6:116. [PMID: 24987367 PMCID: PMC4060025 DOI: 10.3389/fnagi.2014.00116] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Accepted: 05/24/2014] [Indexed: 01/22/2023] Open
Affiliation(s)
- Surjyadipta Bhattacharjee
- Departments of Neurology, Neuroscience and Ophthalmology, Louisiana State University Neuroscience Center and Health Sciences Center New Orleans, LA, USA
| | - Yuhai Zhao
- Departments of Neurology, Neuroscience and Ophthalmology, Louisiana State University Neuroscience Center and Health Sciences Center New Orleans, LA, USA
| | - Walter J Lukiw
- Departments of Neurology, Neuroscience and Ophthalmology, Louisiana State University Neuroscience Center and Health Sciences Center New Orleans, LA, USA
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