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Velezmoro Jauregui G, Vukić D, Onyango IG, Arias C, Novotný JS, Texlová K, Wang S, Kovačovicova KL, Polakova N, Zelinkova J, Čarna M, Lacovich V, Head BP, Havas D, Mistrik M, Zorec R, Verkhratsky A, Keegan L, O'Connell MA, Rissman R, Stokin GB. Amyloid precursor protein induces reactive astrogliosis. Acta Physiol (Oxf) 2024; 240:e14142. [PMID: 38584589 DOI: 10.1111/apha.14142] [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: 02/25/2024] [Revised: 03/01/2024] [Accepted: 03/05/2024] [Indexed: 04/09/2024]
Abstract
AIM Astrocytes respond to stressors by acquiring a reactive state characterized by changes in their morphology and function. Molecules underlying reactive astrogliosis, however, remain largely unknown. Given that several studies observed increase in the Amyloid Precursor Protein (APP) in reactive astrocytes, we here test whether APP plays a role in reactive astrogliosis. METHODS We investigated whether APP instigates reactive astroglios by examining in vitro and in vivo the morphology and function of naive and APP-deficient astrocytes in response to APP and well-established stressors. RESULTS Overexpression of APP in cultured astrocytes led to remodeling of the intermediate filament network, enhancement of cytokine production, and activation of cellular programs centered around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion abrogated remodeling of the intermediate filament network and blunted expression of IFN-stimulated gene products in response to lipopolysaccharide. Following traumatic brain injury (TBI), mouse reactive astrocytes also exhibited an association between APP and IFN, while APP deletion curbed the increase in glial fibrillary acidic protein observed canonically in astrocytes in response to TBI. CONCLUSIONS The APP thus represents a candidate molecular inducer and regulator of reactive astrogliosis. This finding has implications for understanding pathophysiology of neurodegenerative and other diseases of the nervous system characterized by reactive astrogliosis and opens potential new therapeutic avenues targeting APP and its pathways to modulate reactive astrogliosis.
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Affiliation(s)
- Gretsen Velezmoro Jauregui
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Dragana Vukić
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- Faculty of Science, National Centre for Biomedical Research, Masaryk University, Brno, Czech Republic
| | - Isaac G Onyango
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
| | - Carlos Arias
- Department of Neurosciences, University of California San Diego, La Jolla, California, USA
| | - Jan S Novotný
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University Olomouc, Olomouc, Czech Republic
| | - Kateřina Texlová
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
| | - Shanshan Wang
- Veterans Affairs San Diego Healthcare System, San Diego, USA
- Department of Anesthesia, University of California San Diego, La Jolla, California, USA
| | | | - Natalie Polakova
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University Olomouc, Olomouc, Czech Republic
| | - Jana Zelinkova
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University Olomouc, Olomouc, Czech Republic
| | - Maria Čarna
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University Olomouc, Olomouc, Czech Republic
| | - Valentina Lacovich
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Brian P Head
- Veterans Affairs San Diego Healthcare System, San Diego, USA
- Department of Anesthesia, University of California San Diego, La Jolla, California, USA
| | | | - Martin Mistrik
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University Olomouc, Olomouc, Czech Republic
| | - Robert Zorec
- Laboratory of Neuroendocrinology, Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
- Celica Biomedical, Technology Park, Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Achucarro Centre for Neuroscience, IIKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, Liaoning Province, China
| | - Liam Keegan
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Mary A O'Connell
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Robert Rissman
- Department of Neurosciences, University of California San Diego, La Jolla, California, USA
| | - Gorazd B Stokin
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University Olomouc, Olomouc, Czech Republic
- Department of Neurology, Gloucestershire Royal Hospital, Gloucestershire NHS Foundation Trust, Gloucester, UK
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2
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Zeng J, Liao Z, Yang H, Wang Q, Wu Z, Hua F, Zhou Z. T cell infiltration mediates neurodegeneration and cognitive decline in Alzheimer's disease. Neurobiol Dis 2024; 193:106461. [PMID: 38437992 DOI: 10.1016/j.nbd.2024.106461] [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: 11/05/2023] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/06/2024] Open
Abstract
Alzheimer's disease (AD) is a prevalent neurodegenerative disorder with pathological features of β-amyloid (Aβ) and hyperphosphorylated tau protein accumulation in the brain, often accompanied by cognitive decline. So far, our understanding of the extent and role of adaptive immune responses in AD has been quite limited. T cells, as essential members of the adaptive immune system, exhibit quantitative and functional abnormalities in the brains of AD patients. Dysfunction of the blood-brain barrier (BBB) in AD is considered one of the factors leading to T cell infiltration. Moreover, the degree of neuronal loss in AD is correlated with the quantity of T cells. We first describe the differentiation and subset functions of peripheral T cells in AD patients and provide an overview of the key findings related to BBB dysfunction and how T cells infiltrate the brain parenchyma through the BBB. Furthermore, we emphasize the risk factors associated with AD, including Aβ, Tau protein, microglial cells, apolipoprotein E (ApoE), and neuroinflammation. We discuss their regulation of T cell activation and proliferation, as well as the connection between T cells, neurodegeneration, and cognitive decline. Understanding the innate immune response is crucial for providing comprehensive personalized therapeutic strategies for AD.
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Affiliation(s)
- Junjian Zeng
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China
| | - Zhiqiang Liao
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China
| | - Hanqin Yang
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China
| | - Qiong Wang
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China
| | - Zhiyong Wu
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China
| | - Fuzhou Hua
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China.
| | - Zhidong Zhou
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, 330006 Nanchang, Jiangxi, China; Key Laboratory of Anesthesiology of Jiangxi Province, 1# Minde Road, 330006 Nanchang City, Jiangxi Province, China.
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3
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Jauregui GV, Vukić D, Onyango IG, Arias C, Novotný JS, Texlová K, Wang S, Kovačovicova KL, Polakova N, Zelinkova J, Čarna M, Strašil VL, Head BP, Havas D, Mistrik M, Zorec R, Verkhratsky A, Keegan L, O'Connel M, Rissman R, Stokin GB. Amyloid precursor protein induces reactive astrogliosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.18.571817. [PMID: 38187544 PMCID: PMC10769227 DOI: 10.1101/2023.12.18.571817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
We present in vitro and in vivo evidence demonstrating that Amyloid Precursor Protein (APP) acts as an essential instigator of reactive astrogliosis. Cell-specific overexpression of APP in cultured astrocytes led to remodelling of the intermediate filament network, enhancement of cytokine production and activation of cellular programs centred around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion in cultured astrocytes abrogated remodelling of the intermediate filament network and blunted expression of IFN stimulated gene (ISG) products in response to lipopolysaccharide (LPS). Following traumatic brain injury (TBI), mouse reactive astrocytes also exhibited an association between APP and IFN, while APP deletion curbed the increase in glial fibrillary acidic protein (GFAP) observed canonically in astrocytes in response to TBI. Thus, APP represents a molecular inducer and regulator of reactive astrogliosis.
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Affiliation(s)
- Gretsen Velezmoro Jauregui
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
| | - Dragana Vukić
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- National Centre for Biomedical Research, Faculty of Science, Masaryk University, Brno Czech Republic
| | - Isaac G Onyango
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
| | - Carlos Arias
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Jan S Novotný
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
| | - Kateřina Texlová
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
| | - Shanshan Wang
- Veterans Affairs San Diego Healthcare System, San Diego, USA
- Department of Anesthesia, University of California San Diego, San Diego, USA
| | | | - Natalie Polakova
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
| | - Jana Zelinkova
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
| | - Maria Čarna
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
| | | | - Brian P Head
- Veterans Affairs San Diego Healthcare System, San Diego, USA
- Department of Anesthesia, University of California San Diego, San Diego, USA
| | | | - Martin Mistrik
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
| | - Robert Zorec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Celica Biomedical, Technology Park, Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Achucarro Centre for Neuroscience, IIKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- Department of Stem Cell Biology, State Research Institute Centre for innovative Medicine, Vilnius, Lithuania
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, Liaoning Province, China
| | - Liam Keegan
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Mary O'Connel
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Robert Rissman
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Gorazd B Stokin
- Translational Ageing and Neuroscience Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czech Republic
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
- Department of Neurology, Gloucestershire Royal Hospital, Gloucestershire NHS Foundation Trust, Gloucester, UK
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4
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Eckfeld C, Schoeps B, Häußler D, Frädrich J, Bayerl F, Böttcher JP, Knolle P, Heisz S, Prokopchuk O, Hauner H, Munkhbaatar E, Demir IE, Hermann CD, Krüger A. TIMP-1 is a novel ligand of Amyloid Precursor Protein and triggers a proinflammatory phenotype in human monocytes. J Cell Biol 2023; 222:213799. [PMID: 36629908 PMCID: PMC9837626 DOI: 10.1083/jcb.202206095] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/21/2022] [Accepted: 11/28/2022] [Indexed: 01/12/2023] Open
Abstract
The emerging cytokine tissue inhibitor of metalloproteinases-1 (TIMP-1) correlates with the progression of inflammatory diseases, including cancer. However, the effects of TIMP-1 on immune cell activation and underlying molecular mechanisms are largely unknown. Unbiased ligand-receptor-capture-screening revealed TIMP-1-interaction with Amyloid Precursor Protein (APP) family members, namely APP and Amyloid Precursor-like Protein-2 (APLP2), which was confirmed by pull-down assays and confocal microscopy. We found that TIMP-1 triggered glucose uptake and proinflammatory cytokine expression in human monocytes. In cancer patients, TIMP-1 expression positively correlated with proinflammatory cytokine expression and processes associated with monocyte activation. In pancreatic cancer, TIMP-1 plasma levels correlated with the monocyte activation marker sCD163, and the combined use of both clinically accessible plasma proteins served as a powerful prognostic indicator. Mechanistically, TIMP-1 triggered monocyte activation by its C-terminal domain and via APP as demonstrated by in vitro interference, in silico docking, and the employment of recombinant TIMP-1 variants. Identification of TIMP-1 as a trigger of monocyte activation opens new therapeutic perspectives for inflammatory diseases.
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Affiliation(s)
- Celina Eckfeld
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany
| | - Benjamin Schoeps
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany
| | - Daniel Häußler
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany
| | - Julian Frädrich
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany
| | - Felix Bayerl
- School of Medicine, Institute of Molecular Immunology, Technical University of Munich, Munich, Germany
| | - Jan Philipp Böttcher
- School of Medicine, Institute of Molecular Immunology, Technical University of Munich, Munich, Germany
| | - Percy Knolle
- School of Medicine, Institute of Molecular Immunology, Technical University of Munich, Munich, Germany
| | - Simone Heisz
- School of Life Sciences, Else Kröner-Fresenius-Center for Nutritional Medicine, Chair of Nutritional Medicine, Technical University of Munich, Freising-Weihenstephan, Germany
| | - Olga Prokopchuk
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany,Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Hans Hauner
- School of Life Sciences, Else Kröner-Fresenius-Center for Nutritional Medicine, Chair of Nutritional Medicine, Technical University of Munich, Freising-Weihenstephan, Germany,School of Life Sciences, Institute for Nutritional Medicine, Technical University of Munich, Munich, Germany
| | - Enkhtsetseg Munkhbaatar
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Ihsan Ekin Demir
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Chris D. Hermann
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany
| | - Achim Krüger
- https://ror.org/02kkvpp62School of Medicine, Institute of Experimental Oncology and Therapy Research, Technical University of Munich, Munich, Germany,Correspondence to Achim Krüger:
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5
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Secretases Related to Amyloid Precursor Protein Processing. MEMBRANES 2021; 11:membranes11120983. [PMID: 34940484 PMCID: PMC8706128 DOI: 10.3390/membranes11120983] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/24/2021] [Accepted: 12/10/2021] [Indexed: 11/29/2022]
Abstract
Alzheimer’s disease (AD) is a common neurodegenerative disease whose prevalence increases with age. An increasing number of findings suggest that abnormalities in the metabolism of amyloid precursor protein (APP), a single transmembrane aspartic protein that is cleaved by β- and γ-secretases to produce β-amyloid protein (Aβ), are a major pathological feature of AD. In recent years, a large number of studies have been conducted on the APP processing pathways and the role of secretion. This paper provides a summary of the involvement of secretases in the processing of APP and the potential drug targets that could provide new directions for AD therapy.
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Dai L, Shen Y. Insights into T-cell dysfunction in Alzheimer's disease. Aging Cell 2021; 20:e13511. [PMID: 34725916 PMCID: PMC8672785 DOI: 10.1111/acel.13511] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/22/2021] [Accepted: 10/22/2021] [Indexed: 12/11/2022] Open
Abstract
T cells, the critical immune cells of the adaptive immune system, are often dysfunctional in Alzheimer's disease (AD) and are involved in AD pathology. Reports highlight neuroinflammation as a crucial modulator of AD pathogenesis, and aberrant T cells indirectly contribute to neuroinflammation by secreting proinflammatory mediators via direct crosstalk with glial cells infiltrating the brain. However, the mechanisms underlying T‐cell abnormalities in AD appear multifactorial. Risk factors for AD and pathological hallmarks of AD have been tightly linked with immune responses, implying the potential regulatory effects of these factors on T cells. In this review, we discuss how the risk factors for AD, particularly Apolipoprotein E (ApoE), Aβ, α‐secretase, β‐secretase, γ‐secretase, Tau, and neuroinflammation, modulate T‐cell activation and the association between T cells and pathological AD hallmarks. Understanding these associations is critical to provide a comprehensive view of appropriate therapeutic strategies for AD.
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Affiliation(s)
- Linbin Dai
- Institute on Aging and Brain Disorders The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Sciences and Technology of China Hefei China
- Neurodegenerative Disease Research Center University of Science and Technology of China Hefei China
- Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei China
| | - Yong Shen
- Institute on Aging and Brain Disorders The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Sciences and Technology of China Hefei China
- Neurodegenerative Disease Research Center University of Science and Technology of China Hefei China
- Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei China
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Spitzer P, Walter M, Göth C, Oberstein TJ, Linning P, Knölker HJ, Kornhuber J, Maler JM. Pharmacological Inhibition of Amyloidogenic APP Processing and Knock-Down of APP in Primary Human Macrophages Impairs the Secretion of Cytokines. Front Immunol 2020; 11:1967. [PMID: 33013850 PMCID: PMC7494750 DOI: 10.3389/fimmu.2020.01967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/21/2020] [Indexed: 12/18/2022] Open
Abstract
It has been previously shown that the amyloid precursor protein (APP) support the innate immune defense as an immune receptor. Amyloid β (Aβ) peptides seem to have properties of an antimicrobial peptide and can act as opsonines. In APP-deficient mouse models, a reduced secretion of cytokines has been observed. Still, it is unclear whether this can be attributed to the lack of APP or to the missing secretion of Aβ peptides. We inhibited the secretion of Aβ peptides in primary human monocyte derived macrophages with the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine-t-butyl-ester (DAPT) or the β-secretase inhibitor GL-189. Alternatively, we knocked down APP by transfection with siRNA. We measured tumor necrosis factor α (TNFα), interleukin 6 (IL-6) and interleukin (IL-10) by enzyme linked immunosorbent assay (ELISA) and evaluated the phagocytotic activity by flow cytometry. We observed reduced concentrations of TNFα and IL-6 in the media of APPk/d macrophages and after inhibition of the β-, or γ-secretase, especially after additional immunological activation with lipopolysaccharide (LPS). Secretion of IL-10 was increased after pharmacological inhibition of APP processing when the macrophages were not immunologically activated but was decreased during LPS-induced inflammation in APPk/d macrophages. No changes of the phagocytotic activity were observed. We conclude that macrophage APP and Aβ peptides support the initiation of an immune response and are involved in the regulation of TNFα, IL-6, and IL-10 secretion by human monocyte-derived macrophages.
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Affiliation(s)
- Philipp Spitzer
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
| | - Matthias Walter
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
| | - Caroline Göth
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
| | - Timo Jan Oberstein
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
| | - Philipp Linning
- Faculty of Chemistry, Technische Universität Dresden, Dresden, Germany
| | | | - Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
| | - Juan Manuel Maler
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
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8
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Amyloid Beta Peptide (Aβ 1-42) Reverses the Cholinergic Control of Monocytic IL-1β Release. J Clin Med 2020; 9:jcm9092887. [PMID: 32906646 PMCID: PMC7564705 DOI: 10.3390/jcm9092887] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/01/2020] [Accepted: 09/03/2020] [Indexed: 12/14/2022] Open
Abstract
Amyloid-β peptide (Aβ1-42), the cleavage product of the evolutionary highly conserved amyloid precursor protein, presumably plays a pathogenic role in Alzheimer's disease. Aβ1-42 can induce the secretion of the pro-inflammatory cytokine intereukin-1β (IL-1β) in immune cells within and out of the nervous system. Known interaction partners of Aβ1-42 are α7 nicotinic acetylcholine receptors (nAChRs). The physiological functions of Aβ1-42 are, however, not fully understood. Recently, we identified a cholinergic mechanism that controls monocytic release of IL-1β by canonical and non-canonical agonists of nAChRs containing subunits α7, α9, and/or α10. Here, we tested the hypothesis that Aβ1-42 modulates this inhibitory cholinergic mechanism. Lipopolysaccharide-primed monocytic U937 cells and human mononuclear leukocytes were stimulated with the P2X7 receptor agonist 2'(3')-O-(4-benzoylbenzoyl)adenosine-5'-triphosphate triethylammonium salt (BzATP) in the presence or absence of nAChR agonists and Aβ1-42. IL-1β concentrations were measured in the supernatant. Aβ1-42 dose-dependently (IC50 = 2.54 µM) reversed the inhibitory effect of canonical and non-canonical nicotinic agonists on BzATP-mediated IL-1β-release by monocytic cells, whereas reverse Aβ42-1 was ineffective. In conclusion, we discovered a novel pro-inflammatory Aβ1-42 function that enables monocytic IL-1β release in the presence of nAChR agonists. These findings provide evidence for a novel physiological function of Aβ1-42 in the context of sterile systemic inflammation.
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9
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Wang B, Chen T, Wang J, Jia Y, Ren H, Wu F, Hu M, Chen Y. Methamphetamine modulates the production of interleukin-6 and tumor necrosis factor-alpha via the cAMP/PKA/CREB signaling pathway in lipopolysaccharide-activated microglia. Int Immunopharmacol 2018; 56:168-178. [PMID: 29414647 DOI: 10.1016/j.intimp.2018.01.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 01/01/2023]
Abstract
Methamphetamine (METH) elicits neuroinflammatory effects that may implicate its regulatory role on the microglial immune response. However, the mechanism underlying this remains unclear. In the present study, the effects of METH on lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) productions were tested in BV-2 cells and primary microglial cells. Additionally, western blot analysis was used to examine the phosphorylation of mitogenactivated protein kinases (MAPKs). Next, we detected the alterations in cAMP content and the phosphorylation levels of CREB in microglial cells to determine the involvement of the cAMP/CREB signaling pathway. We also used an adenylyl cyclase (AC) agonist (forskolin) and antagonist (MDL-12330A) and a PKA antagonist (H89) to confirm their participation. We observed that METH alone did not affect the production of IL-6 or TNF-α. In contrast, METH augmented the IL-6 production and inhibited the TNF-α production induced by LPS. A similar effect of forskolin was also observed in BV-2 cells. While MAPK activation was not influenced by METH alone, the LPS-induced phosphorylation of p38, JNK and ERK1/2 were all reduced by METH. Both the concentration of cAMP and the phosphorylation of CREB were increased by METH in LPS-activated microglial cells. The effects of METH were altered by MDL-12330A and H89. Moreover, the inhibition of the phosphorylation of ERK1/2 by METH was also reversed. These results suggest that the differential regulation of IL-6 and TNF-α by METH in LPS-activated microglial cells may be attributable to the cAMP/PKA/CREB signaling pathway.
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Affiliation(s)
- Biao Wang
- Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Teng Chen
- Forensic Medicine College of Xi'an Jiaotong University, Key Laboratory of the Health Ministry for Forensic Medicine, Xi'an 710061, China
| | - Jing Wang
- Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Yuwei Jia
- Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Huixun Ren
- Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Feng Wu
- Graduate Teaching and Experiment Centre, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Mei Hu
- Editorial Department of Infectious Disease Information, 302 Hospital of PLA, Beijing 100039, China
| | - Yanjiong Chen
- Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.
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Amyloid precursor protein modulates macrophage phenotype and diet-dependent weight gain. Sci Rep 2017; 7:43725. [PMID: 28262782 PMCID: PMC5338020 DOI: 10.1038/srep43725] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/26/2017] [Indexed: 02/07/2023] Open
Abstract
It is well known that mutations in the gene coding for amyloid precursor protein are responsible for autosomal dominant forms of Alzheimer’s disease. Proteolytic processing of the protein leads to a number of metabolites including the amyloid beta peptide. Although brain amyloid precursor protein expression and amyloid beta production are associated with the pathophysiology of Alzheimer’s disease, it is clear that amyloid precursor protein is expressed in numerous cell types and tissues. Here we demonstrate that amyloid precursor protein is involved in regulating the phenotype of both adipocytes and peripheral macrophages and is required for high fat diet-dependent weight gain in mice. These data suggest that functions of this protein include modulation of the peripheral immune system and lipid metabolism. This biology may have relevance not only to the pathophysiology of Alzheimer’s disease but also diet-associated obesity.
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Manocha GD, Ghatak A, Puig KL, Kraner SD, Norris CM, Combs CK. NFATc2 Modulates Microglial Activation in the AβPP/PS1 Mouse Model of Alzheimer's Disease. J Alzheimers Dis 2017; 58:775-787. [PMID: 28505967 PMCID: PMC6265241 DOI: 10.3233/jad-151203] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease (AD) brains are characterized by fibrillar amyloid-β (Aβ) peptide containing plaques and associated reactive microglia. The proinflammatory phenotype of the microglia suggests that they may negatively affect disease course and contribute to behavioral decline. This hypothesis predicts that attenuating microglial activation may provide benefit against disease. Prior work from our laboratory and others has characterized a role for the transcription factor, nuclear factor of activated T cells (NFAT), in regulating microglial phenotype in response to different stimuli, including Aβ peptide. We observed that the NFATc2 isoform was the most highly expressed in murine microglia cultures, and inhibition or deletion of NFATc2 was sufficient to attenuate the ability of the microglia to secrete cytokines. In order to determine whether the NFATc2 isoform, in particular, was a valid immunomodulatory target in vivo, we crossed an NFATc2-/- line to a well-known AD mouse model, an AβPP/PS1 mouse line. As expected, the AβPP/PS1 x NFATc2-/- mice had attenuated cytokine levels compared to AβPP/PS1 mice as well as reduced microgliosis and astrogliosis with no effect on plaque load. Although some species differences in relative isoform expression may exist between murine and human microglia, it appears that microglial NFAT activity is a viable target for modulating the proinflammatory changes that occur during AD.
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Affiliation(s)
- Gunjan D. Manocha
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Atreyi Ghatak
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Kendra L. Puig
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Susan D. Kraner
- Department of Pharmacology and Nutritional Sciences and the Sanders Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Christopher M. Norris
- Department of Pharmacology and Nutritional Sciences and the Sanders Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Colin K. Combs
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
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Altered Innate Immune and Glial Cell Responses to Inflammatory Stimuli in Amyloid Precursor Protein Knockout Mice. PLoS One 2015; 10:e0140210. [PMID: 26447481 PMCID: PMC4598170 DOI: 10.1371/journal.pone.0140210] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/23/2015] [Indexed: 11/30/2022] Open
Abstract
Amyloid precursor protein (APP) and its cleaved products have been reported to have important functions in CNS health, including in memory and synapse formation, cell survival and neuroprotection. Furthermore APP and its cleaved products have been shown to be transiently increased in response to various CNS stressors, suggesting a role in response to acute cellular injury. In an attempt to further understand the function of APP in response to CNS injury, we have used intracranial LPS injection as an inflammatory injury model in APP knock out mice (APPKO). Our data show that innate immune responses to LPS injection is significantly blunted in APPKO mice compared to APP sufficient wild type (BL6) mice. Morphologically, glial cells in APPKO mice appear less reactive, with shorter ramified processes and smaller cell bodies in response to LPS. Additionally, quantitative RT-PCR analysis for several glia markers and innate immune cytokine levels (e.g. TNFα, IL-6, IL-1β and IL-10) showed significantly reduced expression levels in LPS injected APPKO mice. In vitro cell culture assays confirmed this attenuated response to LPS stimulation by primary microglial cells isolated from APPKO mice. Our data suggests that APP full length protein and/or its cleaved products are necessary to mount a complete and effective innate immune cell response to inflammatory injury.
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Tang W, Tam JHK, Seah C, Chiu J, Tyrer A, Cregan SP, Meakin SO, Pasternak SH. Arf6 controls beta-amyloid production by regulating macropinocytosis of the Amyloid Precursor Protein to lysosomes. Mol Brain 2015; 8:41. [PMID: 26170135 PMCID: PMC4501290 DOI: 10.1186/s13041-015-0129-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 06/11/2015] [Indexed: 11/15/2022] Open
Abstract
Alzheimer’s disease (AD) is characterized by the deposition of Beta-Amyloid (Aβ) peptides in the brain. Aβ peptides are generated by cleavage of the Amyloid Precursor Protein (APP) by the β − and γ − secretase enzymes. Although this process is tightly linked to the internalization of cell surface APP, the compartments responsible are not well defined. We have found that APP can be rapidly internalized from the cell surface to lysosomes, bypassing early and late endosomes. Here we show by confocal microscopy and electron microscopy that this pathway is mediated by macropinocytosis. APP internalization is enhanced by antibody binding/crosslinking of APP suggesting that APP may function as a receptor. Furthermore, a dominant negative mutant of Arf6 blocks direct transport of APP to lysosomes, but does not affect classical endocytosis to endosomes. Arf6 expression increases through the hippocampus with the development of Alzheimer’s disease, being expressed mostly in the CA1 and CA2 regions in normal individuals but spreading through the CA3 and CA4 regions in individuals with pathologically diagnosed AD. Disruption of lysosomal transport of APP reduces both Aβ40 and Aβ42 production by more than 30 %. Our findings suggest that the lysosome is an important site for Aβ production and that altering APP trafficking represents a viable strategy to reduce Aβ production.
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Affiliation(s)
- Weihao Tang
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Joshua H K Tam
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Claudia Seah
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada.
| | - Justin Chiu
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Andrea Tyrer
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Sean P Cregan
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Susan O Meakin
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Biochemistry, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Stephen H Pasternak
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Clinical Neurological Sciences, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
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Puig KL, Manocha GD, Combs CK. Amyloid precursor protein mediated changes in intestinal epithelial phenotype in vitro. PLoS One 2015; 10:e0119534. [PMID: 25742317 PMCID: PMC4351204 DOI: 10.1371/journal.pone.0119534] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/28/2015] [Indexed: 12/13/2022] Open
Abstract
Background Although APP and its proteolytic metabolites have been well examined in the central nervous system, there remains limited information of their functions outside of the brain. For example, amyloid precursor protein (APP) and amyloid beta (Aβ) immunoreactivity have both been demonstrated in intestinal epithelial cells. Based upon the critical role of these cells in absorption and secretion, we sought to determine whether APP or its metabolite amyloid β (Aβ), had a definable function in these cells. Methodology/Principal Findings The human colonic epithelial cell line, Caco-2 cells, were cultured to examine APP expression and Aβ secretion, uptake, and stimulation. Similar to human colonic epithelium stains, Caco-2 cells expressed APP. They also secreted Aβ 1-40 and Aβ 1-42, with LPS stimulating higher concentrations of Aβ 1-40 secretion. The cells also responded to Aβ 1-40 stimulation by increasing IL-6 cytokine secretion and decreasing cholesterol uptake. Conversely, stimulation with a sAPP-derived peptide increased cholesterol uptake. APP was associated with CD36 but not FATP4 in co-IP pull down experiments from the Caco-2 cells. Moreover, stimulation of APP with an agonist antibody acutely decreased CD36-mediated cholesterol uptake. Conclusions/Significance APP exists as part of a multi-protein complex with CD36 in human colonic epithelial cells where its proteolytic fragments have complex, reciprocal roles in regulating cholesterol uptake. A biologically active peptide fragment from the N-terminal derived, sAPP, potentiated cholesterol uptake while the β secretase generated product, Aβ1-40, attenuated it. These data suggest that APP is important in regulating intestinal cholesterol uptake in a fashion dependent upon specific proteolytic pathways. Moreover, this biology may be applicable to cells beyond the gastrointestinal tract.
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Affiliation(s)
- Kendra L. Puig
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Gunjan D. Manocha
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Colin K. Combs
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
- * E-mail:
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15
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Liu HC, Zheng MH, Du YL, Wang L, Kuang F, Qin HY, Zhang BF, Han H. N9 microglial cells polarized by LPS and IL4 show differential responses to secondary environmental stimuli. Cell Immunol 2012; 278:84-90. [DOI: 10.1016/j.cellimm.2012.06.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 04/12/2012] [Accepted: 06/12/2012] [Indexed: 11/28/2022]
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Amyloid precursor protein and proinflammatory changes are regulated in brain and adipose tissue in a murine model of high fat diet-induced obesity. PLoS One 2012; 7:e30378. [PMID: 22276186 PMCID: PMC3261903 DOI: 10.1371/journal.pone.0030378] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 12/19/2011] [Indexed: 11/23/2022] Open
Abstract
Background Middle age obesity is recognized as a risk factor for Alzheimer's disease (AD) although a mechanistic linkage remains unclear. Based upon the fact that obese adipose tissue and AD brains are both areas of proinflammatory change, a possible common event is chronic inflammation. Since an autosomal dominant form of AD is associated with mutations in the gene coding for the ubiquitously expressed transmembrane protein, amyloid precursor protein (APP) and recent evidence demonstrates increased APP levels in adipose tissue during obesity it is feasible that APP serves some function in both disease conditions. Methodology/Principal Findings To determine whether diet-induced obesity produced proinflammatory changes and altered APP expression in brain versus adipose tissue, 6 week old C57BL6/J mice were maintained on a control or high fat diet for 22 weeks. Protein levels and cell-specific APP expression along with markers of inflammation and immune cell activation were compared between hippocampus, abdominal subcutaneous fat and visceral pericardial fat. APP stimulation-dependent changes in macrophage and adipocyte culture phenotype were examined for comparison to the in vivo changes. Conclusions/Significance Adipose tissue and brain from high fat diet fed animals demonstrated increased TNF-α and microglial and macrophage activation. Both brains and adipose tissue also had elevated APP levels localizing to neurons and macrophage/adipocytes, respectively. APP agonist antibody stimulation of macrophage cultures increased specific cytokine secretion with no obvious effects on adipocyte culture phenotype. These data support the hypothesis that high fat diet-dependent obesity results in concomitant pro-inflammatory changes in brain and adipose tissue that is characterized, in part, by increased levels of APP that may be contributing specifically to inflammatory changes that occur.
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17
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Amyloid precursor protein expression modulates intestine immune phenotype. J Neuroimmune Pharmacol 2011; 7:215-30. [PMID: 22124967 DOI: 10.1007/s11481-011-9327-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/14/2011] [Indexed: 12/16/2022]
Abstract
Amyloid precursor protein (APP) is widely expressed across many tissue and cell types. Proteolytic processing of the protein gives rise to a plethora of protein fragments with varied biological activities. Although a large amount of data has been generated describing the metabolism of the protein in neurons, its role in regulating the phenotype of other cells remains unclear. Based upon prior work demonstrating that APP regulates the activation phenotype of monocytic lineage cells, we hypothesized that APP can regulate macrophage activation phenotype in tissues other than brain. Ileums of the small intestines from C57BL6/J wild type and APP(-/-) mice were compared as a representative tissue normally associated with abundant macrophage infiltration. APP(-/-) intestines demonstrated diminished CD68 immunoreactivity compared to wild type mice. This correlated with significantly less cyclooxygenase-2 (cox-2), CD68, CD40, CD11c, and βIII-tubulin protein levels. Peritoneal macrophages from APP(-/-) mice demonstrated decreased in vitro migratory ability compared to wild type cells and diminished basal KC cytokine secretion. Whereas, APP(-/-) intestinal macrophages had an increase in basal KC cytokine secretion compared to wild type cells. Conversely, there was a significant decrease in multiple cytokine levels in APP(-/-) compared to wild type ileums. Finally, APP(-/-) mice demonstrated impaired absorption and increased motility compared to wild type mice. These data demonstrate the APP expression regulates immune cell secretions and phenotype and intestinal function. This data set describes a novel function for this protein or its metabolites that may be relevant not only for Alzheimer's disease but a range of immune-related disorders.
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Dandona P, Mohamed I, Ghanim H, Sia CL, Dhindsa S, Dandona S, Makdissi A, Chaudhuri A. Insulin suppresses the expression of amyloid precursor protein, presenilins, and glycogen synthase kinase-3beta in peripheral blood mononuclear cells. J Clin Endocrinol Metab 2011; 96:1783-8. [PMID: 21411544 PMCID: PMC3100748 DOI: 10.1210/jc.2010-2961] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Our objective was to determine whether peripheral blood mononuclear cells express amyloid precursor protein (APP) and other mediators involved in the pathogenesis of Alzheimer's disease and whether their expression is suppressed by insulin. RESEARCH DESIGN AND METHODS Ten obese type 2 diabetic patients were infused with insulin (2 U/h with 100 ml 5% dextrose/h) for 4 h. Patients were also infused with 5% dextrose/h or normal physiological saline for 4 h, respectively, on two other days as controls. Blood samples were obtained at 0, 2, 4, and 6 h. RESULTS Insulin infusion significantly suppressed the expression of APP, presenilin-1, presenilin-2, and glycogen synthase kinase-3β in peripheral blood mononuclear cells. Dextrose and saline infusions did not alter these indices. Insulin infusion also caused significant parallel reductions in nuclear factor-κB binding activity and plasma concentrations of serum amyloid A and intercellular adhesion molecule-1. CONCLUSIONS A low dose infusion of insulin suppresses APP, presenilin-1, presenilin-2, and glycogen synthase kinase-3β, key proteins involved in the pathogenesis of Alzheimer's disease, in parallel with exerting its other antiinflammatory effects.
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Affiliation(s)
- Paresh Dandona
- Division of Endocrinology, Diabetes, and Metabolism, State University of New York at Buffalo and Kaleida Health, Buffalo, New York 14209, USA.
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Frisardi V, Solfrizzi V, Seripa D, Capurso C, Santamato A, Sancarlo D, Vendemiale G, Pilotto A, Panza F. Metabolic-cognitive syndrome: a cross-talk between metabolic syndrome and Alzheimer's disease. Ageing Res Rev 2010; 9:399-417. [PMID: 20444434 DOI: 10.1016/j.arr.2010.04.007] [Citation(s) in RCA: 234] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 04/23/2010] [Indexed: 02/07/2023]
Abstract
A growing body of epidemiological evidence suggested that metabolic syndrome (MetS) and Mets components (impaired glucose tolerance, abdominal or central obesity, hypertension, hypertriglyceridemia, and reduced high-density lipoprotein cholesterol) may be important in the development of age-related cognitive decline (ARCD), mild cognitive impairment (MCI), vascular dementia, and Alzheimer's disease (AD). These suggestions proposed in these patients the presence of a "metabolic-cognitive syndrome", i.e. a MetS plus cognitive impairment of degenerative or vascular origin. This could represent a pathophysiological model in which to study in depth the mechanisms linking MetS and MetS components with dementia, particularly AD, and predementia syndromes (ARCD or MCI), suggesting a possible integrating view of the MetS components and their influence on cognitive decline. In the present article, we discussed the role of these factors in the development of cognitive decline and dementia, including underlying mechanisms, supporting their influence on β-amyloid peptide metabolism and tau protein hyperphosphorylation, the principal neuropathological hallmarks of AD. In the next future, trials could then be undertaken to determine if modifications of these MetS components including inflammation, another factor probably related to MetS, could lower risk of developing cognitive decline. Future research aimed at identifying mechanisms that underlie comorbid associations of MetS components will not only provide important insights into the causes and interdependencies of predementia and dementia syndromes, but will also inspire novel strategies for treating and preventing cognitive disorders.
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MESH Headings
- Aged
- Aged, 80 and over
- Aging/physiology
- Aging/psychology
- Alzheimer Disease/epidemiology
- Alzheimer Disease/metabolism
- Alzheimer Disease/physiopathology
- Alzheimer Disease/therapy
- Amyloid beta-Peptides/metabolism
- Animals
- Biomarkers/metabolism
- Cholesterol, HDL/blood
- Cholesterol, HDL/standards
- Comorbidity
- Diabetes Mellitus, Type 2/epidemiology
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/physiopathology
- Diabetes Mellitus, Type 2/therapy
- Effect Modifier, Epidemiologic
- Humans
- Hyperlipidemias/blood
- Hyperlipidemias/epidemiology
- Hyperlipidemias/metabolism
- Hyperlipidemias/physiopathology
- Hyperlipidemias/therapy
- Hypertension/epidemiology
- Hypertension/metabolism
- Hypertension/physiopathology
- Hypertension/therapy
- Life Style
- Metabolic Syndrome/epidemiology
- Metabolic Syndrome/metabolism
- Metabolic Syndrome/physiopathology
- Metabolic Syndrome/therapy
- Mice
- Obesity, Abdominal/epidemiology
- Obesity, Abdominal/metabolism
- Obesity, Abdominal/physiopathology
- Obesity, Abdominal/therapy
- Population Dynamics
- Risk Factors
- tau Proteins/metabolism
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Affiliation(s)
- Vincenza Frisardi
- Department of Geriatrics, Center for Aging Brain, Memory Unit, University of Bari, Policlinico, Piazza Giulio Cesare, 11, 70124, Bari, Italy.
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Abstract
Age-associated changes within an individual are inherently complex and occur at multiple levels of organismal function. The overall decline in function of various tissues is known to play a key role in both aging and the complex etiology of certain age-associated diseases such as Alzheimer's disease (AD) and cancer. Continuing research highlights the dynamic capacity of polyphenols to protect against age-associated disorders through a variety of important mechanisms. Numerous lines of evidence suggest that dietary polyphenols such as resveratrol, (-)-epigallocatechin-3-gallate (EGCG), and curcumin have the capacity to mitigate age-associated cellular damage induced via metabolic production of reactive oxygen species (ROS). However, recently acquired evidence also demonstrates a likely role for these polyphenols as anticancer agents capable of preventing formation of new vasculature in neoplastic tissues. Polyphenols have also been shown to possess other anticancer properties such as specific cell-signaling actions that may stimulate the activity of the regulatory protein SIRT1. Additionally, polyphenolic compounds have demonstrated their inhibitory effects against chronic vascular inflammation associated with atherosclerosis. These increasingly well-documented results have begun to provide a basis for considering the use of polyphenols in the development of novel therapies for certain human diseases. And while the mechanisms by which these effects occur are yet to be fully understood, it is evident that further investigation may yield a potential use for polyphenols as pharmacological interventions against specific age-associated diseases.
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Affiliation(s)
- Brannon L Queen
- Department of Biology, University of Alabama at Birmingham, AL 35294, USA
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21
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Sondag CM, Combs CK. Adhesion of monocytes to type I collagen stimulates an APP-dependent proinflammatory signaling response and release of Abeta1-40. J Neuroinflammation 2010; 7:22. [PMID: 20302643 PMCID: PMC2850892 DOI: 10.1186/1742-2094-7-22] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 03/19/2010] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Amyloid precursor protein (APP) is a ubiquitously expressed cell surface protein reported to be involved in mediating cell-cell or cell-matrix interactions. Prior work has demonstrated that APP co-localizes with beta1 integrin in different cell types. METHODS In an effort to determine the function of APP on monocytic lineage cells, in particular, the human monocyte cell line, THP-1, was used to assess the role of APP during adhesion to the extracelluar matrix component type I collagen. RESULTS Pull-down assays demonstrated that THP-1 adhesion to collagen stimulated a tyrosine kinase-associated signaling response which included subsequent phosphorylation of p38 MAP kinase and increased association of APP with alpha2beta1 integrin, specifically. In addition, cell adhesion was dependent upon APP expression since APP siRNA knockdown attenuated THP-1 adhesion to collagen compared to mock transfected controls. One consequence of the tyrosine kinase-dependent signaling response was increased secretion of interleukin-1beta (IL-1beta) and Abeta1-40 but not the Abeta1-42 fragment of APP. Increased secretion of IL-1beta was dependent upon p38 MAP kinase activity while Abeta1-40 secretion required Src family kinase activity since the specific p38 inhibitor, SB202190, and the Src family kinase inhibitor, PP2, attenuated IL-1beta and Abeta1-40 secretion, respectively. CONCLUSIONS These data demonstrate that APP is involved in classic integrin-dependent tyrosine kinase-associated adhesion and activation of peripheral monocytic cells. Moreover, divergent APP-dependent signaling is required for increased secretion of both IL-1beta and Abeta1-40 as a component of the adhesion-dependent change in phenotype. This suggests that APP may have a broad role in not only mediating cell-matrix adhesion but also in the function of peripheral immune cells.
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Affiliation(s)
- Cindy M Sondag
- Department of Pharmacology, Physiology & Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, USA
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22
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Sommer G, Kralisch S, Lipfert J, Weise S, Krause K, Jessnitzer B, Lössner U, Blüher M, Stumvoll M, Fasshauer M. Amyloid precursor protein expression is induced by tumor necrosis factor α in 3T3-L1 adipocytes. J Cell Biochem 2009; 108:1418-22. [DOI: 10.1002/jcb.22382] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Sondag CM, Dhawan G, Combs CK. Beta amyloid oligomers and fibrils stimulate differential activation of primary microglia. J Neuroinflammation 2009; 6:1. [PMID: 19123954 PMCID: PMC2632990 DOI: 10.1186/1742-2094-6-1] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 01/05/2009] [Indexed: 12/31/2022] Open
Abstract
Background Beta amyloid (Aβ) peptides are the major constituents of the senile plaques present in Alzheimer's diseased brain. Pathogenesis has been associated with the aggregated form of the peptide as these fibrils are the conformation readily found in the plaques. However, recent studies have shown that the nonaggregated, soluble assemblies of Aβ have the potential to stimulate neuronal dysfunction and may play a prominent role in the pathogenesis of Alzheimer's disease. Methods Soluble, synthetic Aβ1–42 oligomers were prepared producing mainly dimer-trimer conformations as assessed by SDS-PAGE. Similar analysis demonstrated fibril preparations to produce large insoluble aggregates unable to migrate out of the stacking portion of the gels. These peptide preparations were used to stimulate primary murine microglia and cortical neuron cultures. Microglia were analyzed for changes in signaling response and secretory phenotype via Western analysis and ELISA. Viability was examined by quantifying lactate dehydrogenase release from the cultures. Results Aβ oligomers and fibrils were used to stimulate microglia for comparison. Both the oligomers and fibrils stimulated proinflammatory activation of primary microglia but the specific conformation of the peptide determined the activation profile. Oligomers stimulated increased levels of active, phosphorylated Lyn and Syk kinase as well as p38 MAP kinase compared to fibrils. Moreover, oligomers stimulated a differential secretory profile for interleukin 6, monocyte chemoattractant protein-1 and keratinocyte chemoattractant when compared to fibrils. Finally, soluble oligomers stimulated death of cultured cortical neurons that was exacerbated by the presence of microglia. Conclusion These data suggest that fibrils and oligomers stimulate unique signaling responses in microglia leading to discrete secretory changes and effects on neuron survival. This suggests that inflammation changes during disease may be the consequence of unique peptide-stimulated events and each conformation may represent an individual anti-inflammatory therapeutic target.
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Affiliation(s)
- Cindy M Sondag
- Department of Pharmacology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, USA.
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Maler JM, Spitzer P, Klafki HW, Esselmann H, Lewczuk P, Kornhuber J, Herrmann M, Wiltfang J. Distinct fractional Aβ release patterns in human mononuclear phagocytes. J Neuroimmunol 2009; 206:1-4. [DOI: 10.1016/j.jneuroim.2008.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 08/21/2008] [Accepted: 08/22/2008] [Indexed: 10/21/2022]
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Austin SA, Combs CK. Amyloid precursor protein mediates monocyte adhesion in AD tissue and apoE(-)/(-) mice. Neurobiol Aging 2008; 31:1854-66. [PMID: 19058878 DOI: 10.1016/j.neurobiolaging.2008.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 10/07/2008] [Accepted: 10/17/2008] [Indexed: 10/21/2022]
Abstract
Amyloid precursor protein (APP) is a type 1 integral membrane protein, which is highly conserved and ubiquitously expressed. Numerous data suggest it functions in cellular adhesion. For example, APP binds components of the extracellular matrix to propagate intracellular signaling responses. In order to investigate adhesion-related changes in inflamed vasculature, brains from apolipoprotein E(-/-) (apoE(-/-)) mice were examined for changes related to APP then compared to human Alzheimer's disease (AD) brains. Cerebrovasculature from mouse apoE(-)/(-) and human AD brains revealed strong immunoreactivity for APP, APP phosphorylated at tyrosine residue 682 (pAPP) and Aβ. Further, Western blot analyses from mouse apoE(-/-) and AD brains showed statistically higher protein levels of APP, pAPP and increased APP association with the tyrosine kinase, Src. Lastly, utilizing a modified Stamper-Woodruff adhesion assay, we demonstrated that adhesion of monocytic cells to apoE(-/-) and AD brain endothelium is partially APP dependent. These data suggest that endothelial APP function coupled with increased Aβ production are involved in the vascular dysfunction associated with atherosclerosis and AD.
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Affiliation(s)
- Susan A Austin
- Department of Pharmacology, Physiology & Therapeutics, University of North Dakota, School of Medicine and Health Sciences, 504 Hamline St., Room 116, Grand Forks, ND 58203, United States
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Maler JM, Spitzer P, Klafki HW, Esselmann H, Bibl M, Lewczuk P, Kornhuber J, Herrmann M, Wiltfang J. Adherence-dependent shifts in the patterns of beta-amyloid peptides secreted by human mononuclear phagocytes. Brain Behav Immun 2008; 22:1044-1048. [PMID: 18511234 DOI: 10.1016/j.bbi.2008.04.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2008] [Revised: 04/01/2008] [Accepted: 04/09/2008] [Indexed: 01/13/2023] Open
Abstract
Cells of the mononuclear phagocyte system are closely associated with vascular and neuritic beta-amyloid deposits in Alzheimer's disease. Using one-dimensional and newly developed two-dimensional Abeta-SDS-PAGE Western immunoblot techniques (1D/2D-Abeta-WIB) we investigated the patterns of Abeta peptides released by primary non-adherent and adherence-activated human mononuclear phagocytes in vitro. An overall increase of total released Abeta peptides (Abeta(total)) was observed in adherence-activated mononuclear phagocyte cultures. 2D-Abeta-WIB revealed that the proportion of Abeta(1-40) decreased significantly to 50.2+/-5.4% (n=10) of Abeta(total) compared to 65.9+/-5.6% (n=7) in non-adherent cultures (p<0.0001, t=5.82). Abeta(1-42) accounted for only 3.0+/-2.1% of Abeta(total) and its proportion did not change significantly upon adherence (2.8+/-0.5% of Abeta(total)). In adherence-activated cultures we detected pronounced shifts in the fractional pattern of released Abeta peptides in favour of N-truncated species. The second most prominent Abeta peptide accounted for as much as 12.7+/-3.0% of Abeta(total) (2.0+/-1.2% in non-adherent cultures; p<0.0001, t=9.00) and was identified as Abeta(2-40) by comigration with a synthetic peptide and by N-terminal-specific antibodies. A strong increase of a further Abeta immunoreactive spot migrating at pI 5.45 was observed. It accounted for 9.2+/-1.7% of Abeta(total) as compared to 1.0+/-0.9% in non-adherent cultures (p<0.0001, t=11.61) and presumably represented a variant of Abeta(2-40) as determined by C-terminal Abeta(40)-specific immunoprecipitation and N-terminal-specific immunodetection. Thus, mononuclear phagocytes might be one source of the N-truncated Abeta peptides regularly found in human plasma and are less likely to contribute substantially to plasma Abeta(1-42).
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Affiliation(s)
- Juan Manuel Maler
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Philipp Spitzer
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Hans-Wolfgang Klafki
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Hermann Esselmann
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; Department of Psychiatry and Psychotherapy, University of Essen, Virchowstr. 174, D-45147 Essen, Germany
| | - Mirko Bibl
- Department of Psychiatry and Psychotherapy, University of Essen, Virchowstr. 174, D-45147 Essen, Germany
| | - Piotr Lewczuk
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Martin Herrmann
- Department of Medicine III, Institute for Clinical Immunology, University of Erlangen-Nuremberg, Glückstr. 4a, D-91054 Erlangen, Germany
| | - Jens Wiltfang
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; Department of Psychiatry and Psychotherapy, University of Essen, Virchowstr. 174, D-45147 Essen, Germany
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Lee YH, Tharp WG, Maple RL, Nair S, Permana PA, Pratley RE. Amyloid precursor protein expression is upregulated in adipocytes in obesity. Obesity (Silver Spring) 2008; 16:1493-500. [PMID: 18483477 DOI: 10.1038/oby.2008.267] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The aim of this study was to determine whether amyloid precursor protein (APP) is expressed in human adipose tissue, dysregulated in obesity, and related to insulin resistance and inflammation. APP expression was examined by microarray expression profiling of subcutaneous abdominal adipocytes (SAC) and cultured preadipocytes from obese and nonobese subjects. Quantitative real-time PCR (QPCR) was performed to confirm differences in APP expression in SAC and to compare APP expression levels in adipose tissue, adipocytes, and stromal vascular cells (SVCs) from subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) specimens. Adipose tissue samples were also examined by western blot and immunofluorescence confocal microscopy. Microarray studies demonstrated that APP mRNA expression levels were higher in SAC (approximately 2.5-fold) and preadipocytes (approximately 1.4) from obese subjects. Real-time PCR confirmed increased APP expression in SAC in a separate group of obese compared with nonobese subjects (P=0.02). APP expression correlated to in vivo indices of insulin resistance independently of BMI and with the expression of proinflammatory genes, such as monocyte chemoattractant protein-1 (MCP-1) (R=0.62, P=0.004), macrophage inflammatory protein-1alpha (MIP-1alpha) (R=0.60, P=0.005), and interleukin-6 (IL-6) (R=0.71, P=0.0005). Full-length APP protein was detected in adipocytes by western blotting and APP and its cleavage peptides, Abeta40 and Abeta42, were observed in SAT and VAT by immunofluorescence confocal microscopy. In summary, APP is highly expressed in adipose tissue, upregulated in obesity, and expression levels correlate with insulin resistance and adipocyte cytokine expression levels. These data suggest a possible role for APP and/or Abeta in the development of obesity-related insulin resistance and adipose tissue inflammation.
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Affiliation(s)
- Yong-Ho Lee
- Diabetes and Metabolism Translational Medicine Unit, University of Vermont College of Medicine, Burlington, Vermont, USA
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Sabayan B, Foroughinia F, Mowla A, Borhanihaghighi A. Role of insulin metabolism disturbances in the development of Alzheimer disease: mini review. Am J Alzheimers Dis Other Demen 2008; 23:192-9. [PMID: 18198237 PMCID: PMC10846104 DOI: 10.1177/1533317507312623] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Alzheimer disease (AD) is the most common form of dementia. Different pathogenic processes have been studied that underlie characteristic changes of AD, including A beta protein aggregation, tau phosphorylation, neurovascular dysfunction, and inflammatory processes. Insulin exerts pleiotropic effects in neurons, such as the regulation of neural proliferation, apoptosis, and synaptic transmission. In this setting, any disturbance in the metabolism of insulin in the central nervous system (CNS) may put unfavorable effects on CNS function. It seems that disturbances in insulin metabolism, especially insulin resistance, play a role in most pathogenic processes that promote the development of AD. In this article, the relationships of disturbances in the metabolism of insulin in CNS with A beta peptides aggregation, tau protein phosphorylation, inflammatory markers, neuron apoptosis, neurovascular dysfunction, and neurotransmitter modulation are discussed, and future research directions are provided.
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Affiliation(s)
- Behnam Sabayan
- Student Research Center, Shiraz University of Medical Sciences, Shiraz, Islamic Republic of Iran
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Floden AM, Combs CK. Microglia repetitively isolated from in vitro mixed glial cultures retain their initial phenotype. J Neurosci Methods 2007; 164:218-24. [PMID: 17553568 PMCID: PMC2041803 DOI: 10.1016/j.jneumeth.2007.04.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 04/23/2007] [Accepted: 04/26/2007] [Indexed: 01/25/2023]
Abstract
In vitro culture of rodent microglia is a common system used to model proinflammatory changes in the brain. However, typical postnatal brain isolation protocols are time consuming and cell numbers acquired are often a rate-limiting factor for experimental progress. Large studies that rely on the use of primary microglia can, therefore, require excessive numbers of animals at considerable expense, additional technical support and culture incubator space. Although the addition of mitogens such as macrophage colony-stimulating factor, granulocyte macrophage-colony stimulating factor, and epidermal growth factor to the cultures can facilitate a higher yield, this adds additional expense and likely alters the microglial phenotype. We have defined a simple, inexpensive modification of our standard culture protocol that allows us to repetitively isolate microglia. In order to define a method for improving microglia yield, we utilized our standard mixed glial culture preparation derived from postnatal day 1-3 mouse brains. After isolating microglia from mixed cultures at 14 days in vitro, we added fresh media to the cultures for an additional 7 and 14 days to monitor microglial proliferation. We acquired a constant number of cells at each successive time point although the numbers were reduced from the first isolation. More importantly, in order to determine if our successive microglia isolates differed phenotypically we characterized several parameters of function. We compared their ability to secrete the proinflammatory cytokines interleukin-6 and tumor necrosis factor alpha after LPS stimulation. We also contrasted the phagocytic ability, morphology, and specific immunoreactivity (CD11b, CD68, CD45 and MHC II) of the culture ages. Our data demonstrate that microglia can be obtained from extended-time cultures provided periodic isolation is performed. Moreover, the cells retain a comparable in vitro phenotype. This demonstrates that cells from all ages can be combined for any given study. These findings are a viable and inexpensive way to increase and extend the microglial yield without increasing the number of animals used or adding costly mitogens. This method will be particularly useful for the preparation of microglia cultures from limited transgenic colonies.
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Affiliation(s)
- A M Floden
- Department of Pharmacology, Physiology & Therapeutics, University of North Dakota School of Medicine and Health Sciences, Neuroscience Building, 504 Hamline Street, Grand Forks, ND 58202-9037, United States
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Gralle M, Ferreira ST. Structure and functions of the human amyloid precursor protein: the whole is more than the sum of its parts. Prog Neurobiol 2007; 82:11-32. [PMID: 17428603 DOI: 10.1016/j.pneurobio.2007.02.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 10/26/2006] [Accepted: 02/01/2007] [Indexed: 12/30/2022]
Abstract
The amyloid precursor protein (APP) is a transmembrane protein that plays major roles in the regulation of several important cellular functions, especially in the nervous system, where it is involved in synaptogenesis and synaptic plasticity. The secreted extracellular domain of APP, sAPPalpha, acts as a growth factor for many types of cells and promotes neuritogenesis in post-mitotic neurons. Alternative proteolytic processing of APP releases potentially neurotoxic species, including the amyloid-beta (Abeta) peptide that is centrally implicated in the pathogenesis of Alzheimer's disease (AD). Reinforcing this biochemical link to neuronal dysfunction and neurodegeneration, APP is also genetically linked to AD. In this review, we discuss the biological functions of APP in the context of tissue morphogenesis and restructuring, where APP appears to play significant roles both as a contact receptor and as a diffusible factor. Structural investigation of APP, which is necessary for a deeper understanding of its roles at a molecular level, has also been advancing rapidly. We summarize recent progress in the determination of the structure of isolated APP fragments and of the conformations of full-length sAPPalpha, in both monomeric and dimeric states. The potential role of APP dimerization for the regulation of its biological functions is also discussed.
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Affiliation(s)
- Matthias Gralle
- Instituto de Bioquímica Médica, Programa de Bioquímica e Biofísica Celular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21944-590, Brazil.
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Abstract
Integrins are of interest to neuroscientists because they and many of their ligands are widely expressed in the nervous system and have been shown to have diverse roles in neural development and function (Clegg et al., 2003; Li and Pleasure, 2005; Pinkstaff et al., 1998, 1999; Reichardt and Tomaselli, 1991; Schmid et al., 2005). Integrins have also been implicated in control of pathogenesis in several neurodegenerative diseases, brain tumor pathogenesis, and the aftermath of brain and peripheral nervous system injury (Condic, 2001; Ekstrom et al., 2003; Kloss et al., 1999; Verdier and Penke, 2004; Wallquist et al., 2004). Using integrin antagonists as therapeutic agents in a variety of neurological diseases is of great interest at present (Blackmore and Letourneau, 2006; Mattern et al., 2005; Polman et al., 2006; Wang et al., 2006). In this chapter, we describe methods used in our laboratory to characterize neuronal responses to extracellular matrix proteins, and procedures for assessing integrin roles in neuronal cell attachment and differentiation.
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Affiliation(s)
- Sumiko Denda
- Shiseido Research Center 2, Kanazawa-ku, Yokohama, Japan
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