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Fessel J. The several ways to authentically cure Alzheimer's dementia. Ageing Res Rev 2023; 92:102093. [PMID: 37865143 DOI: 10.1016/j.arr.2023.102093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/11/2023] [Accepted: 10/11/2023] [Indexed: 10/23/2023]
Abstract
Although drugs may slow its progression, authentic cure of AD has never been accomplished. Here, six approaches are suggested that might achieve genuine cure. The six therapies include: 1) treatments addressing levels of TGF-β and Wnt/β-catenin, that become significantly reduced after MCI transitions to AD, and addressing also the impaired epithelial-to-mesenchymal transition (EMT) in AD's pathogenesis; 2) and 3) are two formulations that address the inadequate counter-responses to initial loss of cognition; 4) treatments addressing the brain cells whose impaired functions result in MCI and dementia; 5) the need for using partner drugs even when a particular drug addresses a single pathogenetic cause such as amyloid deposition; 6) enhancing the likelihood of genuine cure by using combinations of approaches chosen from the foregoing. Briefly, genuine cure of AD is possible; however, since AD denotes not one but multiple, phenotypically similar conditions, no one therapy can be generalized to all cases.
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Affiliation(s)
- Jeffrey Fessel
- Department of Medicine, University of California, 2069 Filbert Street, San Francisco, CA 94123, USA.
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2
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Fessel J. Analysis of Why Alzheimer's Dementia Never Spontaneously Reverses, Suggests the Basis for Curative Treatment. J Clin Med 2023; 12:4873. [PMID: 37510988 PMCID: PMC10381682 DOI: 10.3390/jcm12144873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/13/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
A paradox regarding Alzheimer's dementia (AD) and mild cognitive impairment (MCI) is thats spontaneous cure of AD has never been reported, whereas spontaneous cure for MCI occurs fequently. This article analyzes what accounts for this difference. It holds that it is not merely because, for any condition, a stage is reached beyond which it cannot be reversed, since even widely metastatic cancer would be curable were there effective chemotherapy and rheumatoid arthritis became controllable when immune-suppressant treatment was introduced; thus, so could AD be reversible via effective therapy. The analysis presented leads to an explanation of the paradox that is in four categories: (1) levels of transforming growth factor-β are significantly reduced after the transition from MCI to AD; (2) levels of Wnt/β-catenin are significantly reduced after the transition; (3) there is altered epidermal-mesenchymal transition (EMT) in neurons after the transition; (4) there may be risk factors that are either newly operative or pre-existing but worsened at the time of transition, that are particular to individual patients. It is suggested that addressing and ameliorating all of those four categories might cure AD. Medications to address and ameliorate each of the four categories are described.
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Affiliation(s)
- Jeffrey Fessel
- Department of Medicine, University of California, 2069 Filbert Street, San Francisco, CA 94123, USA
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3
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TGF-β as a Key Modulator of Astrocyte Reactivity: Disease Relevance and Therapeutic Implications. Biomedicines 2022; 10:biomedicines10051206. [PMID: 35625943 PMCID: PMC9138510 DOI: 10.3390/biomedicines10051206] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/12/2022] [Accepted: 05/20/2022] [Indexed: 02/06/2023] Open
Abstract
Astrocytes are essential for normal brain development and functioning. They respond to brain injury and disease through a process referred to as reactive astrogliosis, where the reactivity is highly heterogenous and context-dependent. Reactive astrocytes are active contributors to brain pathology and can exert beneficial, detrimental, or mixed effects following brain insults. Transforming growth factor-β (TGF-β) has been identified as one of the key factors regulating astrocyte reactivity. The genetic and pharmacological manipulation of the TGF-β signaling pathway in animal models of central nervous system (CNS) injury and disease alters pathological and functional outcomes. This review aims to provide recent understanding regarding astrocyte reactivity and TGF-β signaling in brain injury, aging, and neurodegeneration. Further, it explores how TGF-β signaling modulates astrocyte reactivity and function in the context of CNS disease and injury.
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4
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Ma R, Kutchy NA, Chen L, Meigs DD, Hu G. Primary cilia and ciliary signaling pathways in aging and age-related brain disorders. Neurobiol Dis 2022; 163:105607. [PMID: 34979259 PMCID: PMC9280856 DOI: 10.1016/j.nbd.2021.105607] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 12/08/2021] [Accepted: 12/30/2021] [Indexed: 12/12/2022] Open
Abstract
Brain disorders are characterized by the progressive loss of structure and function of the brain as a consequence of progressive degeneration and/or death of nerve cells. Aging is a major risk factor for brain disorders such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and stroke. Various cellular and molecular events have been shown to play a role in the progress of neurodegenerative diseases. Emerging studies suggest that primary cilia could be a key regulator in brain diseases. The primary cilium is a singular cellular organelle expressed on the surface of many cell types, such as astrocytes and neurons in the mature brain. Primary cilia detect extracellular cues, such as Sonic Hedgehog (SHH) protein, and transduce these signals into cells to regulate various signaling pathways. Abnormalities in ciliary length and frequency (ratio of ciliated cells) have been implicated in various human diseases, including brain disorders. This review summarizes current findings and thoughts on the role of primary cilia and ciliary signaling pathways in aging and age-related brain disorders.
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Affiliation(s)
- Rong Ma
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA; Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Naseer A Kutchy
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA; Department of Anatomy, Physiology and Pharmacology, School of Veterinary Medicine, St. George's University, Grenada
| | - Liang Chen
- Department of Computer Science, College of Engineering, Shantou University, Shantou, Guangdong 515063, China; Key Laboratory of Intelligent Manufacturing Technology, Ministry of Education, Shantou University, Shantou, Guangdong 515063, China
| | - Douglas D Meigs
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Guoku Hu
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA.
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5
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Dietary Protein Source Influences Brain Inflammation and Memory in a Male Senescence-Accelerated Mouse Model of Dementia. Mol Neurobiol 2020; 58:1312-1329. [PMID: 33169333 DOI: 10.1007/s12035-020-02191-y] [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] [Received: 07/16/2020] [Accepted: 10/29/2020] [Indexed: 12/21/2022]
Abstract
Dementia is a pathological condition characterized by a decline in memory, as well as in other cognitive and social functions. The cellular and molecular mechanisms of brain damage in dementia are not completely understood; however, neuroinflammation is involved. Evidence suggests that chronic inflammation may impair cognitive performance and that dietary protein source may differentially influence this process. Dietary protein source has previously been shown to modify systemic inflammation in mouse models. Thus, we aimed to investigate the effect of chronic dietary protein source substitution in an ageing and dementia male mouse model, the senescence-accelerated mouse-prone 8 (SAMP8) model. We observed that dietary protein source differentially modified memory as shown by inhibitory avoidance testing at 4 months of age. Also, dietary protein source differentially modified neuroinflammation and gliosis in male SAMP8 mice. Our results suggest that chronic dietary protein source substitution may influence brain ageing and memory-related mechanisms in male SAMP8 mice. Moreover, the choice of dietary protein source in mouse diets for experimental purposes may need to be carefully considered when interpreting results.
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Li YQ, Chen Y, Fang JY, Jiang SQ, Li P, Li F. Integrated network pharmacology and zebrafish model to investigate dual-effects components of Cistanche tubulosa for treating both Osteoporosis and Alzheimer's Disease. JOURNAL OF ETHNOPHARMACOLOGY 2020; 254:112764. [PMID: 32173426 DOI: 10.1016/j.jep.2020.112764] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 03/02/2020] [Accepted: 03/10/2020] [Indexed: 06/10/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Osteoporosis (OP) and Alzheimer's disease (AD) are common geriatric concurrent diseases, and many studies indicate the connection of their pathogenesis. Cistanche tubulosa (Schenk) Wight (CT) is a widely used traditional Chinese medicine and has been extensively applied to treat OP and AD, respectively. However, the active ingredients for both concurrent diseases simultaneously and underlying mechanisms are limited. AIM OF STUDY This work aimed at establishing an effective and reliable network screening method to find dual-effects compounds in CT that can protect AD and OP concurrently. And it will provide new perspectives of the link between OP and AD on molecular mechanisms. MATERIAL AND METHODS The dual-effects of CT were systematically analyzed with integrating multiple databases and extensive analysis at a network pharmacology level. Classified drug-target interaction network was constructed to reveal differences in effects between different types of compounds. To prove the effectiveness of this network, some compounds were selected to verify in Pre-induced OP model and AlCl3-induced AD model of zebrafish according to the topological parameters. RESULTS 22 dual-effects active ingredients in CT were initially screened out via network pharmacology with a closely connection with 81 OP and AD-related targets. Classified network analysis found the better bioactivities of phenylethanoid glycosides and flavonoids. The dual-effects of four selected compounds demonstrated that the network is reasonable and effective, suggesting the dual-effects of the remaining 18 compounds. Moreover, we identified 9 putative targets and two pathways that were significantly related to OP and AD. CONCLUSIONS We successfully identified 22 dual-effects active components in CT. This systematic screening strategy provided a new protocol to objectively discover multi-effects compounds of traditional Chinese medicine, and even a macroscopic perspective that will improve our understanding of the link between OP and AD on molecular mechanisms.
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Affiliation(s)
- Ying-Qi Li
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Yi Chen
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Jia-Yi Fang
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Si-Qi Jiang
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Ping Li
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China.
| | - Fei Li
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China; College of Pharmacy, Xinjiang Medical University, Urumqi, 830011, China.
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7
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Ghanbari M, Munshi ST, Ma B, Lendemeijer B, Bansal S, Adams HH, Wang W, Goth K, Slump DE, den Hout MC, IJcken WF, Bellusci S, Pan Q, Erkeland SJ, Vrij FM, Kushner SA, Ikram MA. A functional variant in the miR‐142 promoter modulating its expression and conferring risk of Alzheimer disease. Hum Mutat 2019; 40:2131-2145. [DOI: 10.1002/humu.23872] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 06/13/2019] [Accepted: 07/11/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Mohsen Ghanbari
- Department of Epidemiology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
- Department of Genetics, School of Medicine Mashhad University of Medical Sciences Mashhad Iran
| | - Shashini T. Munshi
- Department of Psychiatry, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Buyun Ma
- Department of Gastroenterology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Bas Lendemeijer
- Department of Psychiatry, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Sakshi Bansal
- Department of Psychiatry, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Hieab H. Adams
- Department of Epidemiology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
- Department of Clinical Genetics, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
- Department of Radiology and Nuclear Medicine, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Wenshi Wang
- Department of Gastroenterology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Kerstin Goth
- Department of Lung Matrix Remodeling, Excellence Cluster Cardio‐Pulmonary System (ECCPS) University Justus Liebig Giessen Giessen Germany
| | - Denise E. Slump
- Department of Psychiatry, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Mirjam C.G.N. den Hout
- Center for Biomics, Department of Cell Biology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Wilfred F.J. IJcken
- Center for Biomics, Department of Cell Biology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Saverio Bellusci
- Department of Lung Matrix Remodeling, Excellence Cluster Cardio‐Pulmonary System (ECCPS) University Justus Liebig Giessen Giessen Germany
| | - Qiuwei Pan
- Department of Gastroenterology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Stefan J. Erkeland
- Department of Immunology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Femke M.S. Vrij
- Department of Psychiatry, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - Steven A. Kushner
- Department of Psychiatry, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
| | - M. Arfan Ikram
- Department of Epidemiology, Erasmus MC University Medical Center Rotterdam Rotterdam the Netherlands
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Li C, Zug C, Qu H, Schluesener H, Zhang Z. Hesperidin ameliorates behavioral impairments and neuropathology of transgenic APP/PS1 mice. Behav Brain Res 2015; 281:32-42. [DOI: 10.1016/j.bbr.2014.12.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/01/2014] [Accepted: 12/06/2014] [Indexed: 12/29/2022]
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Zhang ZY, Li C, Zug C, Schluesener HJ. Icariin ameliorates neuropathological changes, TGF-β1 accumulation and behavioral deficits in a mouse model of cerebral amyloidosis. PLoS One 2014; 9:e104616. [PMID: 25101849 PMCID: PMC4125230 DOI: 10.1371/journal.pone.0104616] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 07/14/2014] [Indexed: 12/24/2022] Open
Abstract
Icariin, a major constituent of flavonoids from the Chinese medicinal herb Epimedium brevicornum, exhibits multiple biological properties, including anti-inflammatory, neuroregulatory and neuroprotective activities. Therefore, Icariin might be applied in treatment of neurodegenerative disorders, including Alzheimer's disease (AD), which is neuropathologically characterized by β-amyloid aggregation, hyperphosphorylated tau and neuroinflammation. Potential therapeutic effects of Icariin were investigated in an animal model of cerebral amyloidosis for AD, transgenic APP/PS1 mouse. Icariin was suspended in carboxymethylcellulose and given orally to APP/PS1 mice. Therapeutic effects were monitored by behavioral tests, namely nesting assay, before and during the experimental treatment. Following an oral treatment of 10 days, Icariin significantly attenuated Aβ deposition, microglial activation and TGF-β1 immunoreactivity at amyloid plaques in cortex and hippocampus of transgenic mice 5 months of age, and restored impaired nesting ability. Our results suggest that Icariin might be considered a promising therapeutic option for human AD.
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Affiliation(s)
- Zhi-Yuan Zhang
- Division of Immunopathology of the Nervous System, Institute of Pathology and Neuropathology, University of Tuebingen, Tuebingen, Germany
- * E-mail:
| | - Chaoyun Li
- Division of Immunopathology of the Nervous System, Institute of Pathology and Neuropathology, University of Tuebingen, Tuebingen, Germany
| | - Caroline Zug
- Division of Immunopathology of the Nervous System, Institute of Pathology and Neuropathology, University of Tuebingen, Tuebingen, Germany
| | - Hermann J. Schluesener
- Division of Immunopathology of the Nervous System, Institute of Pathology and Neuropathology, University of Tuebingen, Tuebingen, Germany
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10
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Joniec-Maciejak I, Ciesielska A, Wawer A, Sznejder-Pachołek A, Schwenkgrub J, Cudna A, Hadaczek P, Bankiewicz KS, Członkowska A, Członkowski A. The influence of AAV2-mediated gene transfer of human IL-10 on neurodegeneration and immune response in a murine model of Parkinson's disease. Pharmacol Rep 2014; 66:660-9. [PMID: 24948069 DOI: 10.1016/j.pharep.2014.03.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 03/09/2014] [Accepted: 03/13/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND The aim of this study was to examine the effect of AAV2-hIL-10 (vector containing cDNA for human interleukin 10) on dopaminergic system activity (measured as DA levels and TH mRNA expression in mouse striata), and other monoamine and amino acid neurotransmitters concentration as well as development of inflammatory processes (measured as TGF-β, IFN-γ and GFAP mRNA expression) in a murine MPTP neurotoxicant model of Parkinson's disease. METHODS Male C57BL/6 mice 12 months-old were used in this study. AAV2-hIL-10 vector was bilaterally administered into striatum at 14, 21 or 28 days prior to MPTP intoxication. Animals were sacrificed at 7 days following MPTP injection. The expression of hIL-10 (human interleukin 10) was examined by ELISA. Striatal monoamine and amino acid neurotransmitters were measured by HPLC method. TH, TGF-β, IFN-γ and GFAP mRNA expression was examined by RT-PCR method. RESULTS MPTP treatment dramatically reduced DA levels and decreased TH mRNA expression in mouse striata, effects that were significantly impeded by AAV2-hIL-10 administration prior to MPTP intoxication. AAV2-hIL-10 infusion increased IFN-γ, TGF-β and GFAP mRNA expression. CONCLUSIONS Our data suggest that the transfer of AAV2-hIL-10 into the striatum may play a neuroprotective role in the mouse MPTP model of PD and these effects are mediated by the anti-inflammatory action of IL-10.
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Affiliation(s)
- Ilona Joniec-Maciejak
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Warsaw, Poland.
| | - Agnieszka Ciesielska
- Department of Neurosurgery, University of California at San Francisco, San Francisco, CA, USA
| | - Adriana Wawer
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Warsaw, Poland
| | - Anna Sznejder-Pachołek
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Warsaw, Poland
| | - Joanna Schwenkgrub
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Warsaw, Poland
| | - Agnieszka Cudna
- Second Department of Neurology, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Piotr Hadaczek
- Department of Neurosurgery, University of California at San Francisco, San Francisco, CA, USA
| | - Kristof S Bankiewicz
- Department of Neurosurgery, University of California at San Francisco, San Francisco, CA, USA
| | - Anna Członkowska
- Second Department of Neurology, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Andrzej Członkowski
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Warsaw, Poland
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11
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Fernández-Botrán R, Ahmed Z, Crespo FA, Gatenbee C, Gonzalez J, Dickson DW, Litvan I. Cytokine expression and microglial activation in progressive supranuclear palsy. Parkinsonism Relat Disord 2011; 17:683-8. [PMID: 21741294 DOI: 10.1016/j.parkreldis.2011.06.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/18/2011] [Accepted: 06/04/2011] [Indexed: 01/10/2023]
Abstract
Although little is known about the etiology of progressive supranuclear palsy (PSP), genetic and epigenetic factors, oxidative injury and inflammation are thought to contribute to its development and/or progression. Evidence for activated glia involvement in PSP has raised the possibility that neuroinflammation may contribute to its pathogenesis. To investigate the correlation between neuroinflammation and PSP, a comparative study was conducted on the patterns of cytokine expression in different regions of the brains of PSP, Alzheimer's disease (AD) patients and normal controls. Our results show different patterns of cytokine expression in each disease, with the expression of IL-1β transcripts being significantly higher in the substantia nigra of PSP than in AD and controls, while AD brains had significantly higher IL-1β expression in the parietal cortex compared to PSP and controls. In addition, expression of TGFβ was significantly higher in the cortical areas (particularly frontal and parietal lobes) of AD compared to PSP and controls. These results show a disease-specific topographical relationship among the expression of certain cytokines (IL-1β and TGFβ), microglial activation and neurodegenerative changes, suggesting that these cytokines may contribute to the pathologic process. If so, the use of cytokine-inhibitors and/or other anti-inflammatory agents may be able to slow disease progression in PSP.
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Affiliation(s)
- Rafael Fernández-Botrán
- Department of Pathology and Laboratory Medicine, School of Medicine, University of Louisville, Louisville, KY 40292, USA.
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12
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Eslami P, Johnson MF, Terzakaryan E, Chew C, Harris-White ME. TGF beta2-induced changes in LRP-1/T beta R-V and the impact on lysosomal A beta uptake and neurotoxicity. Brain Res 2008; 1241:176-87. [PMID: 18804458 DOI: 10.1016/j.brainres.2008.08.086] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 08/21/2008] [Accepted: 08/25/2008] [Indexed: 01/01/2023]
Abstract
Numerous studies suggest a central role for the low-density lipoprotein receptor-related protein/transforming growth factor beta receptor V in Alzheimer's Disease. We continue our investigation of a ligand for this receptor, transforming growth factor beta2, which is also implicated in Alzheimer Disease pathogenesis, but whose mechanism(s) remain elusive. Confocal imaging reveals that transforming growth factor beta2 rapidly targets amyloid beta peptide to the lysosomal compartment in cortical neurons and induces cell death. Low-density lipoprotein receptor-related protein/transforming growth factor beta receptor V is known as an endocytic receptor, delivering proteins to the lysosomal compartment for degradation. Transforming growth factor beta2 may alter this pathway resulting in increased uptake, intracellular accumulation and toxicity of amyloid beta peptide. RT-PCR and Western blot analysis of transforming growth factor beta2-treated cells demonstrate that transforming growth factor beta2 modestly increases the mRNA and protein levels of low-density lipoprotein receptor-related protein/transforming growth factor beta receptor V as well as increases the uptake activity. Furthermore, transforming growth factor beta2 alters the morphology and numbers of lysosomes in neurons. Lucifer Yellow and lysosomal hydrolase analysis show that transforming growth factor beta2 makes lysosomal membranes unstable and leaky and this effect is exacerbated with the addition of amyloid beta protein. Our data support a key role for low-density lipoprotein receptor-related protein/transforming growth factor beta receptor V in mediating transforming growth factor beta2 enhancement of amyloid beta peptide uptake and neurotoxicity.
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Affiliation(s)
- Pirooz Eslami
- Department of Medicine, University of California, Los Angeles, CA, USA
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13
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Chalmers KA, Love S. Neurofibrillary Tangles May Interfere With Smad 2/3 Signaling in Neurons. J Neuropathol Exp Neurol 2007; 66:158-67. [PMID: 17279001 DOI: 10.1097/nen.0b013e3180303b93] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Transforming growth factor (TGF)-beta is a multifunctional cytokine with anti-inflammatory, reparative and neuroprotective functions. Increased levels of TGFbeta in Alzheimer disease (AD) are associated with perivascular deposition of extracellular matrix, which may impair clearance of beta-amyloid and contribute to the development of cerebral amyloid angiopathy. TGFbeta signaling is transduced by Smad proteins: on TGFbeta receptor activation, Smads 2 and 3 are released from sequestration by microtubules, phosphorylated (forming pSmad2/3), and, together with Smad 4, translocated to the nucleus, where they initiate the transcription of multiple genes. Neuronal microtubule assembly is disturbed in AD when tau, a microtubule-stabilizing protein, is hyperphosphorylated and forms neurofibrillary tangles. We have investigated the relationship between Ser202 phospho-tau and pSmads 2 and 3 in the temporal lobe in AD. Within neurons in control brains, pSmads 2 and 3 were almost exclusively intranuclear. In AD, pSmad 3 bound to phospho-tau (mostly insoluble tau) and accumulated in the cytoplasm of tangle-bearing neurons; this was accompanied by a marked decrease in nuclear pSmad3. pSmads 2 and 3 were also present in neuronal granulovacuolar inclusions. Our findings suggest that neurofibrillary tangles sequester pSmad3, preventing its translocation into the nucleus and the induction of gene transcription. Interference with the Smad signaling may adversely affect survival of tangle-bearing neurons in AD.
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Affiliation(s)
- Katy A Chalmers
- Dementia Research Group, University of Bristol Institute of Clinical Neurosciences, Department of Clinical Science at North Bristol, Frenchay Hospital, Bristol, UK
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Tesseur I, Zou K, Esposito L, Bard F, Berber E, Can JV, Lin AH, Crews L, Tremblay P, Mathews P, Mucke L, Masliah E, Wyss-Coray T. Deficiency in neuronal TGF-beta signaling promotes neurodegeneration and Alzheimer's pathology. J Clin Invest 2006; 116:3060-9. [PMID: 17080199 PMCID: PMC1626127 DOI: 10.1172/jci27341] [Citation(s) in RCA: 258] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Accepted: 08/01/2006] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by progressive neurodegeneration and cerebral accumulation of the beta-amyloid peptide (Abeta), but it is unknown what makes neurons susceptible to degeneration. We report that the TGF-beta type II receptor (TbetaRII) is mainly expressed by neurons, and that TbetaRII levels are reduced in human AD brain and correlate with pathological hallmarks of the disease. Reducing neuronal TGF-beta signaling in mice resulted in age-dependent neurodegeneration and promoted Abeta accumulation and dendritic loss in a mouse model of AD. In cultured cells, reduced TGF-beta signaling caused neuronal degeneration and resulted in increased levels of secreted Abeta and beta-secretase-cleaved soluble amyloid precursor protein. These results show that reduced neuronal TGF-beta signaling increases age-dependent neurodegeneration and AD-like disease in vivo. Increasing neuronal TGF-beta signaling may thus reduce neurodegeneration and be beneficial in AD.
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Affiliation(s)
- Ina Tesseur
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Kun Zou
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Luke Esposito
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Frederique Bard
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Elisabeth Berber
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Judith Van Can
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Amy H. Lin
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Leslie Crews
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Patrick Tremblay
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Paul Mathews
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Lennart Mucke
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Eliezer Masliah
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Tony Wyss-Coray
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.
Gladstone Institute of Neurological Disease and
Department of Neurology, University of California San Francisco, San Francisco, California, USA.
Elan Pharmaceuticals Inc., South San Francisco, California, USA.
Departments of Neuroscience and Pathology, University of California San Diego, San Diego, California, USA.
Center for Dementia Research, New York University School of Medicine, Orangeburg, New York, USA.
Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, California, USA
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15
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Hashimoto Y, Nawa M, Chiba T, Aiso S, Nishimoto I, Matsuoka M. Transforming growth factor β2 autocrinally mediates neuronal cell death induced by amyloid-β. J Neurosci Res 2006; 83:1039-47. [PMID: 16511858 DOI: 10.1002/jnr.20804] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Amyloid beta (Abeta), the major component of the senile plaques of Alzheimer's disease, is implicated in neuronal cell death. We have found that Abeta42, a neurotoxic form of Abeta peptide, induces both neuronal and glial expression of TGFbeta2. We have further demonstrated that the addition into culture media of neutralizing antibody to TGFbeta2 or a large amount of the recombinant soluble amyloid precursor protein alpha, the extracellular domain of amyloid precursor protein (APP) generated by alpha secretase, suppresses death in primary cortical neurons (PCNs) induced by Abeta42 in vitro. Combined with the finding in our recent study indicating that TGFbeta2 is a neuronal cell death-inducing ligand for APP, it is suggested that TGFbeta2 is an autocrinal mediator for Abeta42-induced death in PCNs.
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Affiliation(s)
- Yuichi Hashimoto
- Department of Pharmacology, KEIO University School of Medicine, Shinjuku-ku, Tokyo, Japan
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16
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Hashimoto Y, Chiba T, Yamada M, Nawa M, Kanekura K, Suzuki H, Terashita K, Aiso S, Nishimoto I, Matsuoka M. Transforming growth factor beta2 is a neuronal death-inducing ligand for amyloid-beta precursor protein. Mol Cell Biol 2005; 25:9304-17. [PMID: 16227582 PMCID: PMC1265827 DOI: 10.1128/mcb.25.21.9304-9317.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
APP, amyloid beta precursor protein, is linked to the onset of Alzheimer's disease (AD). We have here found that transforming growth factor beta2 (TGFbeta2), but not TGFbeta1, binds to APP. The binding affinity of TGFbeta2 to APP is lower than the binding affinity of TGFbeta2 to the TGFbeta receptor. On binding to APP, TGFbeta2 activates an APP-mediated death pathway via heterotrimeric G protein G(o), c-Jun N-terminal kinase, NADPH oxidase, and caspase 3 and/or related caspases. Overall degrees of TGFbeta2-induced death are larger in cells expressing a familial AD-related mutant APP than in those expressing wild-type APP. Consequently, superphysiological concentrations of TGFbeta2 induce neuronal death in primary cortical neurons, whose one allele of the APP gene is knocked in with the V642I mutation. Combined with the finding indicated by several earlier reports that both neural and glial expression of TGFbeta2 was upregulated in AD brains, it is speculated that TGFbeta2 may contribute to the development of AD-related neuronal cell death.
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Affiliation(s)
- Yuichi Hashimoto
- Department of Pharmacology, KEIO University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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17
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Lee EO, Kang JL, Chong YH. The amyloid-beta peptide suppresses transforming growth factor-beta1-induced matrix metalloproteinase-2 production via Smad7 expression in human monocytic THP-1 cells. J Biol Chem 2005; 280:7845-53. [PMID: 15632190 DOI: 10.1074/jbc.m409101200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Accumulation of the amyloid-beta (Abeta) peptide in the brain is a crucial factor in the development of Alzheimer disease. Expression of transforming growth factor-beta1 (TGF-beta1), an immunosuppressive cytokine, has been associated in vivo with Abeta accumulation in transgenic mice and recently with Abeta clearance by activated microglia, suggesting its deleterious and beneficial effects in neuronal cells. In this study, we demonstrated that TGF-beta1 stimulated the production of matrix metalloproteinase-2 (MMP-2) in a time- and dose-dependent manner in a human monocytic THP-1 cell line. Notably, we found that Abeta1-42 consistently inhibited the TGF-beta1-induced production of MMP-2, the endogenous gene containing Smad response elements, whereas the reverse peptide, Abeta42-1, evidenced little effect. Additionally, Abeta1-42 reduced TGF-beta1-induced increase in plasminogen activator inhibitor-1 (PAI-1). This inhibitory effect of Abeta1-42 was also seen in human astroglial T98G cell line. Furthermore, Abeta1-42 significantly induced the expression of Smad7, which appears in turn to mediate the Abeta suppression of the TGF-beta1-induced MMP-2 production. Indeed, Smad7 overexpression mimicked the inhibitory effect of Abeta1-42 on TGF-beta1-induced MMP-2 production. Importantly, Abeta1-42 markedly suppressed the transactivation of the transfected reporter construct, p3TP-Lux, which contains TGF-beta1-inducible Smad response elements. This was concomitant with a decreased MMP-2 production in TGF-beta1-treated cells. Inhibition of cellular Smad7 levels via the small interference RNA method significantly ameliorated the Abeta1-42-mediated suppression of TGF-beta1-inducible transcription reporter activity, thereby restoring MMP-2 induction, whereas Smad7 transfection down-regulated TGF-beta1-inducible transcription reporter activity. Collectively, these data suggest that Abeta1-42 may play an important role in the negative regulation of TGF-beta1-induced MMP-2 production via Smad7 expression.
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Affiliation(s)
- Eun Ok Lee
- Department of Microbiology, College of Medicine, Division of Molecular Biology and Neuroscience, Ewha Medical Research Institute, Ewha Womans University, 911-1, Mok-6-dong, Yangcheonku, Seoul 158-710, Korea
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18
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Crews L, Wyss-Coray T, Masliah E. Insights into the pathogenesis of hydrocephalus from transgenic and experimental animal models. Brain Pathol 2004; 14:312-6. [PMID: 15446587 PMCID: PMC8095739 DOI: 10.1111/j.1750-3639.2004.tb00070.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Hydrocephalus is a progressive brain disorder characterized by abnormalities in the flow of cerebrospinal fluid (CSF) and ventricular dilatation that leads to cerebral atrophy, and if left untreated, can be fatal. Genetic mutations, congenital malformations, infectious diseases, intracerebral hemorrhages and tumors are common conditions resulting in hydrocephalus. Although the causes of obstructive hydrocephalus are better understood, the mechanisms resulting in chronic, progressive communicating congenital and acquired hydrocephalus are less well understood. In this regard, recent studies in transgenic (tg) mice suggest that increased expression of cytokines such as TGF-beta1 might play an important role by disrupting the vascular extracellular matrix (ECM) remodeling, promoting hemorrhages, and altering the reabsorption of CSF. In this context, the main objective of this manuscript is to provide an overview on the cellular and molecular mechanisms of hydrocephalus based on studies derived from tg and experimental animal models.
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Affiliation(s)
- Leslie Crews
- Department of Neurosciences, University of California San Diego, La Jolla 92093-0624, USA
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19
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Abstract
The cause of progressive supranuclear palsy (PSP), the most common form of the atypical parkinsonian disorders, is unknown. PSP is characterized by four-repeat tau aggregates in neurons (neurofibrillary tangles) and glia in specific basal ganglia and brainstem areas. A thorough literature review led us to hypothesize that genetic and/or environmental factors contribute to its development. It is likely that inheritance of the H1/H1 tau genotype represents a predisposition to develop PSP requiring other environmental or genetic factors. Less likely, a relatively rare mutation with low penetrance could contribute to the abnormal tau aggregation present in this disorder. The possible role of chemicals in the diet or occupation, hypertension, traumatic brain injury, coffee, and inflammation or oxidative injury are reviewed.
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Affiliation(s)
- Irene Litvan
- Movement Disorder Program, University of Louisville School of Medicine, Louisville, Kentucky, USA.
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20
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Janciauskiene S, Sun YX, Wright HT. Interactions of A beta with endogenous anti-inflammatory agents: a basis for chronic neuroinflammation in Alzheimer's disease. Neurobiol Dis 2002; 10:187-200. [PMID: 12270682 DOI: 10.1006/nbdi.2002.0519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- S Janciauskiene
- Department of Medicine, University Hospital Malmö, 20502 Malmö, Sweden
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21
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Tarkowski E, Issa R, Sjögren M, Wallin A, Blennow K, Tarkowski A, Kumar P. Increased intrathecal levels of the angiogenic factors VEGF and TGF-beta in Alzheimer's disease and vascular dementia. Neurobiol Aging 2002; 23:237-43. [PMID: 11804709 DOI: 10.1016/s0197-4580(01)00285-8] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The aim of the present study was to investigate, in patients with Alzheimer's disease (AD), and vascular dementia (VAD), patterns of local release of vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-beta), two cytokines having a pivotal role in hypoxia-induced angiogenesis. The intrathecal levels of these molecules were related to the clinical severity of these diseases and to the intrathecal levels of beta-amyloid protein. Significantly increased cerebrospinal fluid (CSF) levels of both VEGF and TGF-beta were observed in 20 patients with AD and in 26 patients with VAD compared to healthy controls. Interestingly, there was significant correlation between the CSF levels of TGF-beta and VEGF in all the individuals studied. Our study demonstrates, both in patients with AD and in patients with VAD, an intrathecal production of VEGF, a cytokine which plays a pivotal role in angiogenesis. These results suggest that vascular factors might not only play a role in the pathogenesis of VAD but also in the pathogenesis of AD. In addition, we show in AD and VAD an intrathecal production of TGF-beta, a cytokine exerting on one hand anti-inflammatory and angiogenic properties, but on the other promoting amyloidogenesis.
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22
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Goddard I, Bouras M, Keramidas M, Hendrick JC, Feige JJ, Benahmed M. Transforming growth factor-beta receptor types I and II in cultured porcine leydig cells: expression and hormonal regulation. Endocrinology 2000; 141:2068-74. [PMID: 10830292 DOI: 10.1210/endo.141.6.7498] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The steroidogenic activity of testicular Leydig cells is controlled both by the pituitary hormone (LH) and by growth factors such as transforming growth factor-beta peptides (TGFbeta1, -2, and -3; inhibin/activin; and anti-Mullerian hormone). By using primary cultures of porcine Leydig cells as a model, the aim of the study was to identify and characterize the TGFbeta receptors and to study their regulation by LH/hCG. TGFbeta receptors have been identified and characterized through three different approaches, including cross-linking experiments and Western and Northern blotting analyses. In cross-linking experiments, labeled TGFbeta was shown to bind to three different molecular species of 300, 80, and 53 kDa, which may correspond to the protein betaglycan (also known as TGFbeta type III receptor) and TGFbeta type II and I receptors (TGFbetaRII and TGFbetaRI), respectively. The presence of TGFbetaRI and -RII was further demonstrated by Western blotting analysis using specific polyclonal antibodies. Finally, the expression of betaglycan, TGFbetaRII, and TGFbetaRI messenger RNAs, was confirmed by Northern blotting analysis, as shown by the presence of 6.4-, 4.6-, and 5.8-kb messenger RNAs, respectively. By using a RT-PCR approach, the mediators of the TGFbeta signal, Smads 1-7, were also detected in cultured Leydig cells. TGFbetaRI and TGFbetaRII protein levels were enhanced by hCG/LH in a dose-dependent (maximal effect with 0.3 ng/ml hCG) and time-dependent (maximal effect observed after 48 h of hCG treatment) manner. Furthermore, to determine whether the stimulatory effect of LH/hCG was mediated by testosterone, use was made of aminogluthetimide, an inhibitor of cytochrome P450scc. The inhibition oftestosterone formation did not affect the stimulatory effect of LH/hCG on TGFbetaRI and -RII levels, suggesting that the gonadotropin action is not mediated by the steroid hormone. Together, the present findings demonstrate that the TGFbeta receptors are expressed and are under hormonal (gonadotropin) control in cultured porcine Leydig cells.
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Affiliation(s)
- I Goddard
- INSERM, U-407, Communications Cellulaires en Biologie de la Reproduction, Faculté de Médecine Lyon-Sud, Oullins, France
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