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Melnik M, Miyoshi E, Ma R, Corrada M, Kawas C, Bohannan R, Caraway C, Miller CA, Hinman JD, John V, Bilousova T, Gylys KH. Simultaneous isolation of intact brain cells and cell-specific extracellular vesicles from cryopreserved Alzheimer's disease cortex. J Neurosci Methods 2024; 406:110137. [PMID: 38626853 DOI: 10.1016/j.jneumeth.2024.110137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/25/2024] [Accepted: 04/12/2024] [Indexed: 04/21/2024]
Abstract
BACKGROUND The neuronal and gliaI populations within the brain are tightly interwoven, making isolation and study of large populations of a single cell type from brain tissue a major technical challenge. Concurrently, cell-type specific extracellular vesicles (EVs) hold enormous diagnostic and therapeutic potential in neurodegenerative disorders including Alzheimer's disease (AD). NEW METHOD Postmortem AD cortical samples were thawed and gently dissociated. Following filtration, myelin and red blood cell removal, cell pellets were immunolabeled with fluorescent antibodies and analyzed by flow cytometry. The cell pellet supernatant was applied to a triple sucrose cushion for brain EV isolation. RESULTS Neuronal, astrocyte and microglial cell populations were identified. Cell integrity was demonstrated using calcein AM, which is retained by cells with esterase activity and an intact membrane. For some experiments cell pellets were fixed, permeabilized, and immunolabeled for cell-specific markers. Characterization of brain small EV fractions showed the expected size, depletion of EV negative markers, and enrichment in positive and cell-type specific markers. COMPARISON WITH EXISTING METHODS AND CONCLUSIONS We optimized and integrated established protocols, aiming to maximize information obtained from each human autopsy brain sample. The uniqueness of our method lies in its capability to isolate cells and EVs from a single cryopreserved brain sample. Our results not only demonstrate the feasibility of isolating specific brain cell subpopulations for RNA-seq but also validate these subpopulations at the protein level. The accelerated study of EVs from human samples is crucial for a better understanding of their contribution to neuron/glial crosstalk and disease progression.
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Affiliation(s)
- Mikhail Melnik
- UCLA School of Nursing, Los Angeles, CA 90095, USA; Neuroscience Interdepartmental Program, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | | | - Ricky Ma
- UCLA School of Nursing, Los Angeles, CA 90095, USA
| | - Maria Corrada
- Departments of Neurology, Irvine, CA 92697, USA; Institute for Memory Impairments and Neurological Disorders, UC Irvine, Irvine, CA 92697, USA
| | - Claudia Kawas
- Departments of Neurology, Irvine, CA 92697, USA; Neurobiology & Behavior, Irvine, CA 92697, USA; Institute for Memory Impairments and Neurological Disorders, UC Irvine, Irvine, CA 92697, USA
| | - Ryan Bohannan
- Institute for Memory Impairments and Neurological Disorders, UC Irvine, Irvine, CA 92697, USA
| | - Chad Caraway
- Institute for Memory Impairments and Neurological Disorders, UC Irvine, Irvine, CA 92697, USA
| | | | - Jason D Hinman
- Mary S. Easton Center for Alzheimer's Research at UCLA, Los Angeles, CA 90073, USA; Departments of Neurology, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Varghese John
- Mary S. Easton Center for Alzheimer's Research at UCLA, Los Angeles, CA 90073, USA; Departments of Neurology, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Tina Bilousova
- UCLA School of Nursing, Los Angeles, CA 90095, USA; Mary S. Easton Center for Alzheimer's Research at UCLA, Los Angeles, CA 90073, USA; Departments of Neurology, UCLA School of Medicine, Los Angeles, CA 90095, USA.
| | - Karen H Gylys
- UCLA School of Nursing, Los Angeles, CA 90095, USA; Mary S. Easton Center for Alzheimer's Research at UCLA, Los Angeles, CA 90073, USA; Neuroscience Interdepartmental Program, UCLA School of Medicine, Los Angeles, CA 90095, USA
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Liang Z, Zhuang H, Cao X, Ma G, Shen L. Subcellular proteomics insights into Alzheimer's disease development. Proteomics Clin Appl 2024; 18:e2200112. [PMID: 37650321 DOI: 10.1002/prca.202200112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/27/2023] [Accepted: 08/12/2023] [Indexed: 09/01/2023]
Abstract
Alzheimer's disease (AD), one of the most common dementias, is a neurodegenerative disease characterized by cognitive impairment and decreased judgment function. The expected number of AD patient is increasing in the context of the world's advancing medical care and increasing human life expectancy. Since current molecular mechanism studies on AD pathogenesis are incomplete, there is no specific and effective therapeutic agent. Mass spectrometry (MS)-based unbiased proteomics studies provide an effective and comprehensive approach. Many advances have been made in the study of the mechanism, diagnostic markers, and drug targets of AD using proteomics. This paper focus on subcellular level studies, reviews studies using proteomics to study AD-associated mitochondrial dysfunction, synaptic, and myelin damage, the protein composition of amyloid plaques (APs) and neurofibrillary tangles (NFTs), changes in tissue extracellular vehicles (EVs) and exosome proteome, and the protein changes in ribosomes and lysosomes. The methods of sample separation and preparation and proteomic analysis as well as the main findings of these studies are involved. The results of these proteomics studies provide insights into the pathogenesis of AD and provide theoretical resource and direction for future research in AD, helping to identify new biomarkers and drugs targets for AD.
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Affiliation(s)
- Zhiyuan Liang
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, P. R. China
| | - Hongbin Zhuang
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, P. R. China
| | - Xueshan Cao
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, P. R. China
- College of Physics and Optoelectronics Engineering, Shenzhen University, Shenzhen, P. R. China
| | - Guanwei Ma
- School of Public Health, the key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, P. R. China
| | - Liming Shen
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, P. R. China
- Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, P. R. China
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3
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Allosteric Inhibition of Neutral Sphingomyelinase 2 (nSMase2) by DPTIP: From Antiflaviviral Activity to Deciphering Its Binding Site through In Silico Studies and Experimental Validation. Int J Mol Sci 2022; 23:ijms232213935. [PMID: 36430407 PMCID: PMC9697135 DOI: 10.3390/ijms232213935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/06/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
Flavivirus comprises globally emerging and re-emerging pathogens such as Zika virus (ZIKV), Dengue virus (DENV), and West Nile virus (WNV), among others. Although some vaccines are available, there is an unmet medical need as no effective antiviral treatment has been approved for flaviviral infections. The development of host-directed antivirals (HDAs) targeting host factors that are essential for viral replication cycle offers the opportunity for the development of broad-spectrum antivirals. In the case of flaviviruses, recent studies have revealed that neutral sphingomyelinase 2, (nSMase2), involved in lipid metabolism, plays a key role in WNV and ZIKV infection. As a proof of concept, we have determined the antiviral activity of the non-competitive nSMase2 inhibitor DPTIP against WNV and ZIKV virus. DPTIP showed potent antiviral activity with EC50 values of 0.26 µM and 1.56 µM for WNV and ZIKV, respectively. In order to unravel the allosteric binding site of DPTIP in nSMase2 and the details of the interaction, computational studies have been carried out. These studies have revealed that DPTIP could block the DK switch in nSMase2. Moreover, the analysis of the residues contributing to the binding identified His463 as a crucial residue. Interestingly, the inhibitory activity of DPTIP on the H463A mutant protein supported our hypothesis. Thus, an allosteric cavity in nSMase2 has been identified that can be exploited for the development of new inhibitors with anti-flaviviral activity.
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Polanco JC, Götz J. Exosomal and vesicle-free tau seeds-propagation and convergence in endolysosomal permeabilization. FEBS J 2022; 289:6891-6907. [PMID: 34092031 DOI: 10.1111/febs.16055] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 05/19/2021] [Accepted: 06/04/2021] [Indexed: 01/13/2023]
Abstract
In Alzheimer's disease (AD), β-amyloid peptides aggregate to form amyloid plaques, and the microtubule-associated protein tau forms neurofibrillary tangles. However, severity and duration of AD correlate with the stereotypical emergence of tau tangles throughout the brain, suggestive of a gradual region-to-region spreading of pathological tau. The current notion in the field is that misfolded tau seeds propagate transsynaptically and corrupt the proper folding of soluble tau in recipient neurons. This is supported by accumulating evidence showing that in AD, functional connectivity and not proximity predicts the spreading of tau pathology. Tau seeds can be found in two flavors, vesicle-free, that is, naked as in oligomers and fibrils, or encapsulated by membranes of secreted vesicles known as exosomes. Both types of seeds have been shown to propagate between interconnected neurons. Here, we describe potential ways of how their propagation can be controlled in several subcellular compartments by manipulating mechanisms affecting production, neuron-to-neuron transmission, internalization, endosomal escape, and autophagy. We emphasize that although vesicle-free tau seeds and exosomes differ, they share the ability to trigger endolysosomal permeabilization. Such a mechanistic convergence in endolysosomal permeabilization presents itself as a unique opportunity to target both types of tau seeding. We discuss the cellular response to endolysosomal damage that might be key to control permeabilization, and the significant overlap in the seeding mechanism of proteopathic agents other than tau, which suggests that targeting the endolysosomal pathway could pave the way toward developing broad-spectrum treatments for neurodegenerative diseases.
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Affiliation(s)
- Juan Carlos Polanco
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland, Brisbane, QLD, Australia
| | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland, Brisbane, QLD, Australia
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Tallon C, Bell BJ, Sharma A, Pal A, Malvankar MM, Thomas AG, Yoo SW, Hollinger KR, Coleman K, Wilkinson EL, Kannan S, Haughey NJ, Kannan RM, Rais R, Slusher BS. Dendrimer-Conjugated nSMase2 Inhibitor Reduces Tau Propagation in Mice. Pharmaceutics 2022; 14:2066. [PMID: 36297501 PMCID: PMC9609094 DOI: 10.3390/pharmaceutics14102066] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/11/2022] [Accepted: 09/11/2022] [Indexed: 11/16/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by the progressive accumulation of amyloid-β and hyperphosphorylated tau (pTau), which can spread throughout the brain via extracellular vesicles (EVs). Membrane ceramide enrichment regulated by the enzyme neutral sphingomyelinase 2 (nSMase2) is a critical component of at least one EV biogenesis pathway. Our group recently identified 2,6-Dimethoxy-4-(5-Phenyl-4-Thiophen-2-yl-1H-Imidazol-2-yl)-Phenol (DPTIP), the most potent (30 nM) and selective inhibitor of nSMase2 reported to date. However, DPTIP exhibits poor oral pharmacokinetics (PK), modest brain penetration, and rapid clearance, limiting its clinical translation. To enhance its PK properties, we conjugated DPTIP to a hydroxyl-PAMAM dendrimer delivery system, creating dendrimer-DPTIP (D-DPTIP). In an acute brain injury model, orally administered D-DPTIP significantly reduced the intra-striatal IL-1β-induced increase in plasma EVs up to 72 h post-dose, while oral DPTIP had a limited effect. In a mouse tau propagation model, where a mutant hTau (P301L/S320F) containing adeno-associated virus was unilaterally seeded into the hippocampus, oral D-DPTIP (dosed 3× weekly) significantly inhibited brain nSMase2 activity and blocked the spread of pTau to the contralateral hippocampus. These data demonstrate that dendrimer conjugation of DPTIP improves its PK properties, resulting in significant inhibition of EV propagation of pTau in mice. Dendrimer-based delivery of DPTIP has the potential to be an exciting new therapeutic for AD.
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Affiliation(s)
- Carolyn Tallon
- Johns Hopkins Drug Discovery, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Benjamin J. Bell
- Johns Hopkins Drug Discovery, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Anjali Sharma
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Arindom Pal
- Johns Hopkins Drug Discovery, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | | | - Seung-Wan Yoo
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | - Kaleem Coleman
- Johns Hopkins Drug Discovery, Baltimore, MD 21205, USA
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Elizabeth L. Wilkinson
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Moser Center for Leukodystrophies at Kennedy Krieger, Kennedy Krieger Institute, Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sujatha Kannan
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Hugo W. Moser Research Institute at Kennedy-Krieger Inc., Baltimore, MD 21205, USA
- Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Norman J. Haughey
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Center for Nanomedicine at the Wilmer Eye Institute, Department of Chemical and Biomolecular Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rangaramanujam M. Kannan
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Moser Center for Leukodystrophies at Kennedy Krieger, Kennedy Krieger Institute, Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rana Rais
- Johns Hopkins Drug Discovery, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Barbara S. Slusher
- Johns Hopkins Drug Discovery, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Center for Nanomedicine at the Wilmer Eye Institute, Department of Chemical and Biomolecular Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Johns Hopkins Drug Discovery, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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6
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Murray TE, Richards CM, Robert-Gostlin VN, Bernath AK, Lindhout IA, Klegeris A. Potential neurotoxic activity of diverse molecules released by astrocytes. Brain Res Bull 2022; 189:80-101. [PMID: 35988785 DOI: 10.1016/j.brainresbull.2022.08.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 07/04/2022] [Accepted: 08/14/2022] [Indexed: 11/02/2022]
Abstract
Astrocytes are the main support cells of the central nervous system. They also participate in neuroimmune reactions. In response to pathological and immune stimuli, astrocytes transform to reactive states characterized by increased release of inflammatory mediators. Some of these molecules are neuroprotective and inflammation resolving while others, including reactive oxygen species (ROS), nitric oxide (NO), matrix metalloproteinase (MMP)- 9, L-glutamate, and tumor necrosis factor α (TNF), are well-established toxins known to cause damage to surrounding cells and tissues. We hypothesized that similar to microglia, the brain immune cells, reactive astrocytes can release a broader set of diverse molecules that are potentially neurotoxic. A literature search was conducted to identify such molecules using the following two criteria: 1) evidence of their expression and secretion by astrocytes and 2) direct neurotoxic action. This review describes 14 structurally diverse molecules as less-established astrocyte neurotoxins, including C-X-C motif chemokine ligand (CXCL)10, CXCL12/CXCL12(5-67), FS-7-associated surface antigen ligand (FasL), macrophage inflammatory protein (MIP)- 2α, TNF-related apoptosis inducing ligand (TRAIL), pro-nerve growth factor (proNGF), pro-brain-derived neurotrophic factor (proBDNF), chondroitin sulfate proteoglycans (CSPGs), cathepsin (Cat)B, group IIA secretory phospholipase A2 (sPLA2-IIA), amyloid beta peptides (Aβ), high mobility group box (HMGB)1, ceramides, and lipocalin (LCN)2. For some of these molecules, further studies are required to establish either their direct neurotoxic effects or the full spectrum of stimuli that induce their release by astrocytes. Only limited studies with human-derived astrocytes and neurons are available for most of these potential neurotoxins, which is a knowledge gap that should be addressed in the future. We also summarize available evidence of the role these molecules play in select neuropathologies where reactive astrocytes are a key feature. A comprehensive understanding of the full spectrum of neurotoxins released by reactive astrocytes is key to understanding neuroinflammatory diseases characterized by the adverse activation of these cells and may guide the development of novel treatment strategies.
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Affiliation(s)
- Taryn E Murray
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, British Columbia V1V 1V7, Canada
| | - Christy M Richards
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, British Columbia V1V 1V7, Canada
| | - Victoria N Robert-Gostlin
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, British Columbia V1V 1V7, Canada
| | - Anna K Bernath
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, British Columbia V1V 1V7, Canada
| | - Ivan A Lindhout
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, British Columbia V1V 1V7, Canada
| | - Andis Klegeris
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, British Columbia V1V 1V7, Canada.
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7
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Ghosh S, Ghosh S. Exosome: The “Off-the-Shelf” Cellular Nanocomponent as a Potential Pathogenic Agent, a Disease Biomarker, and Neurotherapeutics. Front Pharmacol 2022; 13:878058. [PMID: 35685643 PMCID: PMC9170956 DOI: 10.3389/fphar.2022.878058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/19/2022] [Indexed: 12/12/2022] Open
Abstract
Exosomes are nanosized “off-the-shelf” lipid vesicles released by almost all cell types and play a significant role in cell–cell communication. Exosomes have already been proven to carry cell-specific cargos of proteins, lipids, miRNA, and noncoding RNA (ribonucleic acid). These vesicles can be selectively taken up by the neighboring cell and can regulate cellular functions. Herein, we have discussed three different roles of exosomes in neuroscience. First, we have discussed how exosomes play the role of a pathogenic agent as a part of cell–cell communication and transmit pathogens such as amyloid-beta (Aβ), further helping in the propagation of neurodegenerative and other neurological diseases. In the next section, the review talks about the role of exosomes in biomarker discovery in neurological disorders. Toward the end, we have reviewed how exosomes can be harnessed and engineered for therapeutic purposes in different brain diseases. This review is based on the current knowledge generated in this field and our comprehension of this domain.
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Extracellular vesicles in the treatment of neurological disorders. Neurobiol Dis 2021; 157:105445. [PMID: 34271084 DOI: 10.1016/j.nbd.2021.105445] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/26/2021] [Accepted: 07/10/2021] [Indexed: 12/28/2022] Open
Abstract
Extracellular vesicles (EVs) are small, cell-derived membranous particles containing various nucleic acids, proteins, and lipids that play essential roles in intercellular communication. Evidence indicating that part of the regenerative benefit from stem cell therapy arises through EVs released from transplanted cells created interest in using EVs for clinical applications. EVs from various cellular sources, including mesenchymal stem cells, neural stem cells, and glia, are efficacious in models of neurological disease. In these models, EVs attenuate reactive gliosis, neuronal death, pro-inflammatory signaling, as well as reduce cognitive, behavioral, and motor deficits. EVs are naturally permeable to the blood-brain barrier and can be modified to contain molecules of interest, thereby also serving as a vehicle to transport therapeutics into the brain. This review summarizes the current state of research using EVs as a treatment in models of neurological disorders and highlights considerations for future research.
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9
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Annadurai N, De Sanctis JB, Hajdúch M, Das V. Tau secretion and propagation: Perspectives for potential preventive interventions in Alzheimer's disease and other tauopathies. Exp Neurol 2021; 343:113756. [PMID: 33989658 DOI: 10.1016/j.expneurol.2021.113756] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/26/2021] [Accepted: 05/10/2021] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is characterised by the accumulation of intracytoplasmic aggregates of tau protein, which are suggested to spread in a prion-like manner between interconnected brain regions. This spreading is mediated by the secretion and uptake of tau from the extracellular space or direct cell-to-cell transmission through cellular protrusions. The prion-like tau then converts the endogenous, normal tau into pathological forms, resulting in neurodegeneration. The endoplasmic reticulum/Golgi-independent tau secretion through unconventional secretory pathways involves delivering misfolded and aggregated tau to the plasma membrane and its release into the extracellular space by non-vesicular and vesicular mechanisms. Although cytoplasmic tau was thought to be released only from degenerating cells, studies now show that cells constitutively secrete tau at low levels under physiological conditions. The mechanisms of secretion of tau under physiological and pathological conditions remain unclear. Therefore, a better understanding of these pathways is essential for developing therapeutic approaches that can target prion-like tau forms to prevent neurodegeneration progression in AD. This review focuses on unconventional secretion pathways involved in the spread of tau pathology in AD and presents these pathways as prospective areas for future AD drug discovery and development.
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Affiliation(s)
- Narendran Annadurai
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 77900 Olomouc, Czech Republic
| | - Juan B De Sanctis
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 77900 Olomouc, Czech Republic
| | - Marián Hajdúch
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 77900 Olomouc, Czech Republic
| | - Viswanath Das
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 5, 77900 Olomouc, Czech Republic.
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10
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Zhu C, Bilousova T, Focht S, Jun M, Elias CJ, Melnik M, Chandra S, Campagna J, Cohn W, Hatami A, Spilman P, Gylys KH, John V. Pharmacological inhibition of nSMase2 reduces brain exosome release and α-synuclein pathology in a Parkinson's disease model. Mol Brain 2021; 14:70. [PMID: 33875010 PMCID: PMC8056538 DOI: 10.1186/s13041-021-00776-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 03/30/2021] [Indexed: 12/11/2022] Open
Abstract
Aim We have previously reported that cambinol (DDL-112), a known inhibitor of neutral sphingomyelinase-2 (nSMase2), suppressed extracellular vesicle (EV)/exosome production in vitro in a cell model and reduced tau seed propagation. The enzyme nSMase2 is involved in the production of exosomes carrying proteopathic seeds and could contribute to cell-to-cell transmission of pathological protein aggregates implicated in neurodegenerative diseases such as Parkinson’s disease (PD). Here, we performed in vivo studies to determine if DDL-112 can reduce brain EV/exosome production and proteopathic alpha synuclein (αSyn) spread in a PD mouse model. Methods The acute effects of single-dose treatment with DDL-112 on interleukin-1β-induced extracellular vesicle (EV) release in brain tissue of Thy1-αSyn PD model mice and chronic effects of 5 week DDL-112 treatment on behavioral/motor function and proteinase K-resistant αSyn aggregates in the PD model were determined. Results/discussion In the acute study, pre-treatment with DDL-112 reduced EV/exosome biogenesis and in the chronic study, treatment with DDL-112 was associated with a reduction in αSyn aggregates in the substantia nigra and improvement in motor function. Inhibition of nSMase2 thus offers a new approach to therapeutic development for neurodegenerative diseases with the potential to reduce the spread of disease-specific proteopathic proteins. Supplementary Information The online version contains supplementary material available at 10.1186/s13041-021-00776-9.
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Affiliation(s)
- Chunni Zhu
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Tina Bilousova
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA.,School of Nursing, University of California, Los Angeles, CA, 90095, USA
| | - Samantha Focht
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Michael Jun
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Chris Jean Elias
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Mikhail Melnik
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Sujyoti Chandra
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Jesus Campagna
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Whitaker Cohn
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Asa Hatami
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | - Patricia Spilman
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA
| | | | - Varghese John
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, CA, 90095, USA.
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11
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Tallon C, Hollinger KR, Pal A, Bell BJ, Rais R, Tsukamoto T, Witwer KW, Haughey NJ, Slusher BS. Nipping disease in the bud: nSMase2 inhibitors as therapeutics in extracellular vesicle-mediated diseases. Drug Discov Today 2021; 26:1656-1668. [PMID: 33798648 DOI: 10.1016/j.drudis.2021.03.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/04/2021] [Accepted: 03/24/2021] [Indexed: 12/11/2022]
Abstract
Extracellular vesicles (EVs) are indispensable mediators of intercellular communication, but they can also assume a nefarious role by ferrying pathological cargo that contributes to neurological, oncological, inflammatory, and infectious diseases. The canonical pathway for generating EVs involves the endosomal sorting complexes required for transport (ESCRT) machinery, but an alternative pathway is induced by the enrichment of lipid membrane ceramides generated by neutral sphingomyelinase 2 (nSMase2). Inhibition of nSMase2 has become an attractive therapeutic strategy for inhibiting EV biogenesis, and a growing number of small-molecule nSMase2 inhibitors have shown promising therapeutic activity in preclinical disease models. This review outlines the function of EVs, their potential role in disease, the discovery and efficacy of nSMase2 inhibitors, and the path to translate these findings into therapeutics.
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Affiliation(s)
- Carolyn Tallon
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kristen R Hollinger
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Arindom Pal
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Benjamin J Bell
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rana Rais
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Takashi Tsukamoto
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kenneth W Witwer
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Norman J Haughey
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Barbara S Slusher
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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12
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Ruan Z, Pathak D, Venkatesan Kalavai S, Yoshii-Kitahara A, Muraoka S, Bhatt N, Takamatsu-Yukawa K, Hu J, Wang Y, Hersh S, Ericsson M, Gorantla S, Gendelman HE, Kayed R, Ikezu S, Luebke JI, Ikezu T. Alzheimer's disease brain-derived extracellular vesicles spread tau pathology in interneurons. Brain 2021; 144:288-309. [PMID: 33246331 PMCID: PMC7880668 DOI: 10.1093/brain/awaa376] [Citation(s) in RCA: 123] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/29/2020] [Accepted: 08/17/2020] [Indexed: 12/16/2022] Open
Abstract
Extracellular vesicles are highly transmissible and play critical roles in the propagation of tau pathology, although the underlying mechanism remains elusive. Here, for the first time, we comprehensively characterized the physicochemical structure and pathogenic function of human brain-derived extracellular vesicles isolated from Alzheimer's disease, prodromal Alzheimer's disease, and non-demented control cases. Alzheimer's disease extracellular vesicles were significantly enriched in epitope-specific tau oligomers in comparison to prodromal Alzheimer's disease or control extracellular vesicles as determined by dot blot and atomic force microscopy. Alzheimer's disease extracellular vesicles were more efficiently internalized by murine cortical neurons, as well as more efficient in transferring and misfolding tau, than prodromal Alzheimer's disease and control extracellular vesicles in vitro. Strikingly, the inoculation of Alzheimer's disease or prodromal Alzheimer's disease extracellular vesicles containing only 300 pg of tau into the outer molecular layer of the dentate gyrus of 18-month-old C57BL/6 mice resulted in the accumulation of abnormally phosphorylated tau throughout the hippocampus by 4.5 months, whereas inoculation of an equal amount of tau from control extracellular vesicles, isolated tau oligomers, or fibrils from the same Alzheimer's disease donor showed little tau pathology. Furthermore, Alzheimer's disease extracellular vesicles induced misfolding of endogenous tau in both oligomeric and sarkosyl-insoluble forms in the hippocampal region. Unexpectedly, phosphorylated tau was primarily accumulated in glutamic acid decarboxylase 67 (GAD67) GABAergic interneurons and, to a lesser extent, glutamate receptor 2/3-positive excitatory mossy cells, showing preferential extracellular vesicle-mediated GABAergic interneuronal tau propagation. Whole-cell patch clamp recordings of CA1 pyramidal cells showed significant reduction in the amplitude of spontaneous inhibitory post-synaptic currents. This was accompanied by reductions in c-fos+ GAD67+ neurons and GAD67+ neuronal puncta surrounding pyramidal neurons in the CA1 region, confirming reduced GABAergic transmission in this region. Our study posits a novel mechanism for the spread of tau in hippocampal GABAergic interneurons via brain-derived extracellular vesicles and their subsequent neuronal dysfunction.
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Affiliation(s)
- Zhi Ruan
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Dhruba Pathak
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Srinidhi Venkatesan Kalavai
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Asuka Yoshii-Kitahara
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Satoshi Muraoka
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Nemil Bhatt
- Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Kayo Takamatsu-Yukawa
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jianqiao Hu
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Yuzhi Wang
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Samuel Hersh
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Maria Ericsson
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Santhi Gorantla
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Howard E Gendelman
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Rakez Kayed
- Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Seiko Ikezu
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jennifer I Luebke
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA 02118, USA
- Center for Systems Neuroscience, Boston University, Boston, MA 02118, USA
| | - Tsuneya Ikezu
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
- Center for Systems Neuroscience, Boston University, Boston, MA 02118, USA
- Department of Neurology and Alzheimer’s Disease Center, Boston University School of Medicine, Boston, MA 02118, USA
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13
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Skácel J, Slusher BS, Tsukamoto T. Small Molecule Inhibitors Targeting Biosynthesis of Ceramide, the Central Hub of the Sphingolipid Network. J Med Chem 2021; 64:279-297. [PMID: 33395289 PMCID: PMC8023021 DOI: 10.1021/acs.jmedchem.0c01664] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ceramides are composed of a sphingosine and a single fatty acid connected by an amide linkage. As one of the major classes of biologically active lipids, ceramides and their upstream and downstream metabolites have been implicated in several pathological conditions including cancer, neurodegeneration, diabetes, microbial pathogenesis, obesity, and inflammation. Consequently, tremendous efforts have been devoted to deciphering the dynamics of metabolic pathways involved in ceramide biosynthesis. Given that several distinct enzymes can produce ceramide, different enzyme targets have been pursued depending on the underlying disease mechanism. The main objective of this review is to provide a comprehensive overview of small molecule inhibitors reported to date for each of these ceramide-producing enzymes from a medicinal chemistry perspective.
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Affiliation(s)
- Jan Skácel
- Johns Hopkins Drug Discovery and Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21205, United States
| | - Barbara S. Slusher
- Johns Hopkins Drug Discovery and Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21205, United States
| | - Takashi Tsukamoto
- Johns Hopkins Drug Discovery and Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21205, United States
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14
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Manjula R, Anuja K, Alcain FJ. SIRT1 and SIRT2 Activity Control in Neurodegenerative Diseases. Front Pharmacol 2021; 11:585821. [PMID: 33597872 PMCID: PMC7883599 DOI: 10.3389/fphar.2020.585821] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/21/2020] [Indexed: 12/12/2022] Open
Abstract
Sirtuins are NAD+ dependent histone deacetylases (HDAC) that play a pivotal role in neuroprotection and cellular senescence. SIRT1-7 are different homologs from sirtuins. They play a prominent role in many aspects of physiology and regulate crucial proteins. Modulation of sirtuins can thus be utilized as a therapeutic target for metabolic disorders. Neurological diseases have distinct clinical manifestations but are mainly age-associated and due to loss of protein homeostasis. Sirtuins mediate several life extension pathways and brain functions that may allow therapeutic intervention for age-related diseases. There is compelling evidence to support the fact that SIRT1 and SIRT2 are shuttled between the nucleus and cytoplasm and perform context-dependent functions in neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). In this review, we highlight the regulation of SIRT1 and SIRT2 in various neurological diseases. This study explores the various modulators that regulate the activity of SIRT1 and SIRT2, which may further assist in the treatment of neurodegenerative disease. Moreover, we analyze the structure and function of various small molecules that have potential significance in modulating sirtuins, as well as the technologies that advance the targeted therapy of neurodegenerative disease.
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Affiliation(s)
- Ramu Manjula
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, United States
| | - Kumari Anuja
- School of Biotechnology, KIIT University, Bhubaneswar, India
| | - Francisco J. Alcain
- Department of Medical Sciences, Faculty of Medicine, University of Castilla-La Mancha, Albacete, Spain
- Oxidative Stress and Neurodegeneration Group, Regional Center for Biomedical Research, University of Castilla-La Mancha, Ciudad Real, Spain
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15
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Exosomal tau with seeding activity is released from Alzheimer's disease synapses, and seeding potential is associated with amyloid beta. J Transl Med 2021; 101:1605-1617. [PMID: 34462532 PMCID: PMC8590975 DOI: 10.1038/s41374-021-00644-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 07/07/2021] [Accepted: 07/09/2021] [Indexed: 01/23/2023] Open
Abstract
Synaptic transfer of tau has long been hypothesized from the human pathology pattern and has been demonstrated in vitro and in vivo, but the precise mechanisms remain unclear. Extracellular vesicles such as exosomes have been suggested as a mechanism, but not all tau is exosomal. The present experiments use a novel flow cytometry assay to quantify depolarization of synaptosomes by KCl after loading with FM2-10, which induces a fluorescence reduction associated with synaptic vesicle release; the degree of reduction in cryopreserved human samples equaled that seen in fresh mouse synaptosomes. Depolarization induced the release of vesicles in the size range of exosomes, along with tetraspanin markers of extracellular vesicles. A number of tau peptides were released, including tau oligomers; released tau was primarily unphosphorylated and C-terminal truncated, with Aβ release just above background. When exosomes were immunopurified from release supernatants, a prominent tau band showed a dark smeared appearance of SDS-stable oligomers along with the exosomal marker syntenin-1, and these exosomes induced aggregation in the HEK tau biosensor assay. However, the flow-through did not seed aggregation. Size exclusion chromatography of purified released exosomes shows faint signals from tau in the same fractions that show a CD63 band, an exosomal size signal, and seeding activity. Crude synaptosomes from control, tauopathy, and AD cases demonstrated lower seeding in tauopathy compared to AD that is correlated with the measured Aβ42 level. These results show that AD synapses release exosomal tau that is C-terminal-truncated, oligomeric, and with seeding activity that is enhanced by Aβ. Taken together with previous findings, these results are consistent with a direct prion-like heterotypic seeding of tau by Aβ within synaptic terminals, with subsequent loading of aggregated tau onto exosomes that are released and competent for tau seeding activity.
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16
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Cohn W, Melnik M, Huang C, Teter B, Chandra S, Zhu C, McIntire LB, John V, Gylys KH, Bilousova T. Multi-Omics Analysis of Microglial Extracellular Vesicles From Human Alzheimer's Disease Brain Tissue Reveals Disease-Associated Signatures. Front Pharmacol 2021; 12:766082. [PMID: 34925024 PMCID: PMC8675946 DOI: 10.3389/fphar.2021.766082] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/19/2021] [Indexed: 12/23/2022] Open
Abstract
Alzheimer's disease (AD) is the most common cause of dementia, yet there is no cure or diagnostics available prior to the onset of clinical symptoms. Extracellular vesicles (EVs) are lipid bilayer-delimited particles that are released from almost all types of cell. Genome-wide association studies have linked multiple AD genetic risk factors to microglia-specific pathways. It is plausible that microglia-derived EVs may play a role in the progression of AD by contributing to the dissemination of insoluble pathogenic proteins, such as tau and Aβ. Despite the potential utility of EVs as a diagnostic tool, our knowledge of human brain EV subpopulations is limited. Here we present a method for isolating microglial CD11b-positive small EVs from cryopreserved human brain tissue, as well as an integrated multiomics analysis of microglial EVs enriched from the parietal cortex of four late-stage AD (Braak V-VI) and three age-matched normal/low pathology (NL) cases. This integrated analysis revealed 1,000 proteins, 594 lipids, and 105 miRNAs using shotgun proteomics, targeted lipidomics, and NanoString nCounter technology, respectively. The results showed a significant reduction in the abundance of homeostatic microglia markers P2RY12 and TMEM119, and increased levels of disease-associated microglia markers FTH1 and TREM2, in CD11b-positive EVs from AD brain compared to NL cases. Tau abundance was significantly higher in AD brain-derived microglial EVs. These changes were accompanied by the upregulation of synaptic and neuron-specific proteins in the AD group. Levels of free cholesterol were elevated in microglial EVs from the AD brain. Lipidomic analysis also revealed a proinflammatory lipid profile, endolysosomal dysfunction, and a significant AD-associated decrease in levels of docosahexaenoic acid (DHA)-containing polyunsaturated lipids, suggesting a potential defect in acyl-chain remodeling. Additionally, four miRNAs associated with immune and cellular senescence signaling pathways were significantly upregulated in the AD group. Our data suggest that loss of the homeostatic microglia signature in late AD stages may be accompanied by endolysosomal impairment and the release of undigested neuronal and myelin debris, including tau, through extracellular vesicles. We suggest that the analysis of microglia-derived EVs has merit for identifying novel EV-associated biomarkers and providing a framework for future larger-scale multiomics studies on patient-derived cell-type-specific EVs.
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Affiliation(s)
- Whitaker Cohn
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Mikhail Melnik
- School of Nursing, University of California, Los Angeles, Los Angeles, CA, United States
| | - Calvin Huang
- School of Nursing, University of California, Los Angeles, Los Angeles, CA, United States
| | - Bruce Teter
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Sujyoti Chandra
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Chunni Zhu
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Laura Beth McIntire
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, United States
| | - Varghese John
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Karen H Gylys
- School of Nursing, University of California, Los Angeles, Los Angeles, CA, United States
| | - Tina Bilousova
- Drug Discovery Lab, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States.,School of Nursing, University of California, Los Angeles, Los Angeles, CA, United States
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17
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Jiang S, Bhaskar K. Degradation and Transmission of Tau by Autophagic-Endolysosomal Networks and Potential Therapeutic Targets for Tauopathy. Front Mol Neurosci 2020; 13:586731. [PMID: 33177989 PMCID: PMC7596180 DOI: 10.3389/fnmol.2020.586731] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/24/2020] [Indexed: 01/21/2023] Open
Abstract
Tauopathies are a class of neurodegenerative diseases, including Alzheimer’s disease (AD), Frontotemporal Dementia (FTD), Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), and many others where microtubule-associated protein tau (MAPT or tau) is hyperphosphorylated and aggregated to form insoluble paired helical filaments (PHFs) and ultimately neurofibrillary tangles (NFTs). Autophagic-endolysosomal networks (AELN) play important roles in tau clearance. Excessive soluble neurotoxic forms of tau and tau hyperphosphorylated at specific sites are cleared through the ubiquitin-proteasome system (UPS), Chaperon-mediated Autophagy (CMA), and endosomal microautophagy (e-MI). On the other hand, intra-neuronal insoluble tau aggregates are often degraded within lysosomes by macroautophagy. AELN defects have been observed in AD, FTD, CBD, and PSP, and lysosomal dysfunction was shown to promote the cleavage and neurotoxicity of tau. Moreover, several AD risk genes (e.g., PICALM, GRN, and BIN1) have been associated with dysregulation of AELN in the late-onset sporadic AD. Conversely, tau dissociation from microtubules interferes with retrograde transport of autophagosomes to lysosomes, and that tau fragments can also lead to lysosomal dysfunction. Recent studies suggest that tau is not merely an intra-neuronal protein, but it can be released to brain parenchyma via extracellular vesicles, like exosomes and ectosomes, and thus spread between neurons. Extracellular tau can also be taken up by microglial cells and astrocytes, either being degraded through AELN or propagated via exosomes. This article reviews the complex roles of AELN in the degradation and transmission of tau, potential diagnostic/therapeutic targets and strategies based on AELN-mediated tau clearance and propagation, and the current state of drug development targeting AELN and tau against tauopathies.
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Affiliation(s)
- Shanya Jiang
- Department of Molecular Genetics and Microbiology, The University of New Mexico, Albuquerque, NM, United States
| | - Kiran Bhaskar
- Department of Molecular Genetics and Microbiology, The University of New Mexico, Albuquerque, NM, United States
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18
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Ishibashi Y, Ito M, Hirabayashi Y. The sirtuin inhibitor cambinol reduces intracellular glucosylceramide with ceramide accumulation by inhibiting glucosylceramide synthase. Biosci Biotechnol Biochem 2020; 84:2264-2272. [PMID: 32705968 DOI: 10.1080/09168451.2020.1794785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The accumulation of glucosylceramide (GlcCer), which is synthesized by UDP-glucose ceramide glucosyltransferase (UGCG), is associated with several diseases, including Gaucher disease and Parkinson's disease. Since the inhibition of UGCG can be used to treat diseases caused by GlcCer accumulation, several UGCG inhibitors have been developed. In this study, we report on the inhibition of UGCG activity by cambinol, a sirtuin inhibitor. Unlike conventional UGCG inhibitors, cambinol has no structural similarity to GlcCer. LC-ESI MS/MS analysis revealed that the cellular GlcCer levels were reduced by cambinol with an increase in ceramide, the GlcCer precursor. Histidine 193 plays an important role in the inhibition of UGCG via a known UGCG inhibitor, D-PDMP. However, cambinol was found to inhibit UGCG activity in a histidine 193-independent manner. This study provides insights into the mechanism of inhibition of UGCG activity by cambinol, and provides a basis for the development of a cambinol-based novel UGCG inhibitor.
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Affiliation(s)
- Yohei Ishibashi
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University , Fukuoka, Japan
| | - Makoto Ito
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University , Fukuoka, Japan
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19
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Bilousova T, Simmons BJ, Knapp RR, Elias CJ, Campagna J, Melnik M, Chandra S, Focht S, Zhu C, Vadivel K, Jagodzinska B, Cohn W, Spilman P, Gylys KH, Garg NK, John V. Dual Neutral Sphingomyelinase-2/Acetylcholinesterase Inhibitors for the Treatment of Alzheimer's Disease. ACS Chem Biol 2020; 15:1671-1684. [PMID: 32352753 DOI: 10.1021/acschembio.0c00311] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We report the discovery of a novel class of compounds that function as dual inhibitors of the enzymes neutral sphingomyelinase-2 (nSMase2) and acetylcholinesterase (AChE). Inhibition of these enzymes provides a unique strategy to suppress the propagation of tau pathology in the treatment of Alzheimer's disease (AD). We describe the key SAR elements that affect relative nSMase2 and/or AChE inhibitor effects and potency, in addition to the identification of two analogs that suppress the release of tau-bearing exosomes in vitro and in vivo. Identification of these novel dual nSMase2/AChE inhibitors represents a new therapeutic approach to AD and has the potential to lead to the development of truly disease-modifying therapeutics.
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Affiliation(s)
- Tina Bilousova
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
- School of Nursing, University of California, Los Angeles, California 90095, United States
| | - Bryan J. Simmons
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Rachel R. Knapp
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Chris J. Elias
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Jesus Campagna
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Mikhail Melnik
- School of Nursing, University of California, Los Angeles, California 90095, United States
| | - Sujyoti Chandra
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Samantha Focht
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Chunni Zhu
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Kanagasabai Vadivel
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Barbara Jagodzinska
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Whitaker Cohn
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Patricia Spilman
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
| | - Karen H. Gylys
- School of Nursing, University of California, Los Angeles, California 90095, United States
| | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Varghese John
- Drug Discovery Laboratory, Department of Neurology, Mary S. Easton Center for Alzheimer’s Disease Research, University of California, Los Angeles, California 90095, United States
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20
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Brunello CA, Merezhko M, Uronen RL, Huttunen HJ. Mechanisms of secretion and spreading of pathological tau protein. Cell Mol Life Sci 2020; 77:1721-1744. [PMID: 31667556 PMCID: PMC7190606 DOI: 10.1007/s00018-019-03349-1] [Citation(s) in RCA: 149] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/10/2019] [Accepted: 10/16/2019] [Indexed: 12/12/2022]
Abstract
Accumulation of misfolded and aggregated forms of tau protein in the brain is a neuropathological hallmark of tauopathies, such as Alzheimer's disease and frontotemporal lobar degeneration. Tau aggregates have the ability to transfer from one cell to another and to induce templated misfolding and aggregation of healthy tau molecules in previously healthy cells, thereby propagating tau pathology across different brain areas in a prion-like manner. The molecular mechanisms involved in cell-to-cell transfer of tau aggregates are diverse, not mutually exclusive and only partially understood. Intracellular accumulation of misfolded tau induces several mechanisms that aim to reduce the cellular burden of aggregated proteins and also promote secretion of tau aggregates. However, tau may also be released from cells physiologically unrelated to protein aggregation. Tau secretion involves multiple vesicular and non-vesicle-mediated pathways, including secretion directly through the plasma membrane. Consequently, extracellular tau can be found in various forms, both as a free protein and in vesicles, such as exosomes and ectosomes. Once in the extracellular space, tau aggregates can be internalized by neighboring cells, both neurons and glial cells, via endocytic, pinocytic and phagocytic mechanisms. Importantly, accumulating evidence suggests that prion-like propagation of misfolding protein pathology could provide a general mechanism for disease progression in tauopathies and other related neurodegenerative diseases. Here, we review the recent literature on cellular mechanisms involved in cell-to-cell transfer of tau, with a particular focus in tau secretion.
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Affiliation(s)
- Cecilia A Brunello
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland
| | - Maria Merezhko
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland
| | - Riikka-Liisa Uronen
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland
| | - Henri J Huttunen
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland.
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21
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Pampuscenko K, Morkuniene R, Sneideris T, Smirnovas V, Budvytyte R, Valincius G, Brown GC, Borutaite V. Extracellular tau induces microglial phagocytosis of living neurons in cell cultures. J Neurochem 2019; 154:316-329. [PMID: 31834946 DOI: 10.1111/jnc.14940] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 02/06/2023]
Abstract
Tau is a microtubule-associated protein, found at high levels in neurons, and its aggregation is associated with neurodegeneration. Recently, it was found that tau can be actively secreted from neurons, but the effects of extracellular tau on neuronal viability are unclear. In this study, we investigated whether extracellular tau2N4R can cause neurotoxicity in primary cultures of rat brain neurons and glial cells. Cell cultures were examined for neuronal loss, death, and phosphatidylserine exposure, as well as for microglial phagocytosis by fluorescence microscopy. Aggregation of tau2N4R was assessed by atomic force microscopy. We found that extracellular addition of tau induced a gradual loss of neurons over 1-2 days, without neuronal necrosis or apoptosis, but accompanied by proliferation of microglia in the neuronal-glial co-cultures. Tau addition caused exposure of the 'eat-me' signal phosphatidylserine on the surface of living neurons, and this was prevented by elimination of the microglia or by inhibition of neutral sphingomyelinase. Tau also increased the phagocytic activity of pure microglia, and this was blocked by inhibitors of neutral sphingomyelinase or protein kinase C. The neuronal loss induced by tau was prevented by inhibitors of neutral sphingomyelinase, protein kinase C or the phagocytic receptor MerTK, or by eliminating microglia from the cultures. The data suggest that extracellular tau induces primary phagocytosis of stressed neurons by activated microglia, and identifies multiple ways in which the neuronal loss induced by tau can be prevented.
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Affiliation(s)
- Katryna Pampuscenko
- Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Ramune Morkuniene
- Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Tomas Sneideris
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Rima Budvytyte
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Gintaras Valincius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Vilmante Borutaite
- Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, Lithuania
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22
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Naseri NN, Wang H, Guo J, Sharma M, Luo W. The complexity of tau in Alzheimer's disease. Neurosci Lett 2019; 705:183-194. [PMID: 31028844 PMCID: PMC7060758 DOI: 10.1016/j.neulet.2019.04.022] [Citation(s) in RCA: 170] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/14/2019] [Accepted: 04/08/2019] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is characterized by two major pathological lesions in the brain, amyloid plaques and neurofibrillary tangles (NFTs) composed mainly of amyloid-β (Aβ) peptides and hyperphosphorylated tau, respectively. Although accumulation of toxic Aβ species in the brain has been proposed as one of the important early events in AD, continued lack of success of clinical trials based on Aβ-targeting drugs has triggered the field to seek out alternative disease mechanisms and related therapeutic strategies. One of the new approaches is to uncover novel roles of pathological tau during disease progression. This review will primarily focus on recent advances in understanding the contributions of tau to AD.
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Affiliation(s)
- Nima N Naseri
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, USA.
| | - Hong Wang
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, USA
| | - Jennifer Guo
- The University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Manu Sharma
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, USA
| | - Wenjie Luo
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, USA.
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23
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Stepanek O, Hin N, Thomas AG, Dash R, Alt J, Rais R, Rojas C, Slusher BS, Tsukamoto T. Neutral sphingomyelinase 2 inhibitors based on the 4-(1H-imidazol-2-yl)-2,6-dialkoxyphenol scaffold. Eur J Med Chem 2019; 170:276-289. [PMID: 30921693 PMCID: PMC9850959 DOI: 10.1016/j.ejmech.2019.03.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 01/21/2023]
Abstract
Neutral sphingomyelinase 2 (nSMase2), a key enzyme in ceramide biosynthesis, is a new therapeutic target for the treatment of neurological disorders and cancer. Using 2,6-dimethoxy-4-[4-phenyl-5-(2-thienyl)-1H-imidazol-2-yl]phenol (DPTIP), our initial hit compound (IC50 = 30 nM) from nSMase2 screening efforts, as a molecular template, a series of 4-(1H-imidazol-2-yl)-2,6-dialkoxyphenol derivatives were designed, synthesized, and evaluated. Systematic examination of various regions of DPTIP identified the key pharmacophore required for potent nSMase2 inhibition as well as a number of compounds with the 4-(1H-imidazol-2-yl)-2,6-dialkoxyphenol scaffold with similar or higher inhibitory potency against nSMase2 as compared to DPTIP. Among them, 4-(4,5-diisopropyl-1H-imidazol-2-yl)-2,6-dimethoxyphenol (25b) was found to be metabolically stable against P450 metabolism in liver microsomes and displayed higher plasma exposure following oral administration as compared to DPTIP. Analysis of plasma samples identified an O-glucuronide as the major metabolite. Blockade of the phase II metabolism should further facilitate our efforts to identify potent nSMase2 inhibitors with desirable ADME properties.
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Affiliation(s)
- Ondrej Stepanek
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Niyada Hin
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Ajit G. Thomas
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Ranjeet Dash
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA,Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jesse Alt
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Rana Rais
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA,Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Camilo Rojas
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA,Department of Molecular and Comparative Pathobiology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Barbara S. Slusher
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA,Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Takashi Tsukamoto
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, USA,Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA,Address correspondence to: Tel: +1-410-614-0982;
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24
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25
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Kumar A, Henry RJ, Stoica BA, Loane DJ, Abulwerdi G, Bhat SA, Faden AI. Neutral Sphingomyelinase Inhibition Alleviates LPS-Induced Microglia Activation and Neuroinflammation after Experimental Traumatic Brain Injury. J Pharmacol Exp Ther 2019; 368:338-352. [PMID: 30563941 PMCID: PMC6367691 DOI: 10.1124/jpet.118.253955] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/14/2018] [Indexed: 12/17/2022] Open
Abstract
Neuroinflammation is one of the key secondary injury mechanisms triggered by traumatic brain injury (TBI). Microglial activation, a hallmark of brain neuroinflammation, plays a critical role in regulating immune responses after TBI and contributes to progressive neurodegeneration and neurologic deficits following brain trauma. Here we evaluated the role of neutral sphingomyelinase (nSMase) in microglial activation by examining the effects of the nSMase inhibitors altenusin and GW4869 in vitro (using BV2 microglia cells and primary microglia), as well as in a controlled cortical injury (CCI) model in adult male C57BL/6 mice. Pretreatment of altenusin or GW4869 prior to lipopolysaccharide (LPS) stimulation for 4 or 24 hours, significantly downregulated gene expression of the pro-inflammatory mediators TNF-α, IL-1β, IL-6, iNOS, and CCL2 in microglia and reduced the release of nitric oxide and TNF-α These nSMase inhibitors also attenuated the release of microparticles and phosphorylation of p38 MAPK and ERK1/2. In addition, altenusin pretreatment also reduced the gene expression of multiple inflammatory markers associated with microglial activation after experimental TBI, including TNF-α, IL-1β, IL-6, iNOS, CCL2, CD68, NOX2, and p22phox Overall, our data demonstrate that nSMase inhibitors attenuate multiple inflammatory pathways associated with microglial activation in vitro and after experimental TBI. Thus, nSMase inhibitors may represent promising therapeutics agents targeting neuroinflammation.
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Affiliation(s)
- Asit Kumar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Gelareh Abulwerdi
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Shahnawaz A Bhat
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland
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