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Lalwani RC, Volmar CH, Wahlestedt C, Webster KA, Shehadeh LA. Contextualizing the Role of Osteopontin in the Inflammatory Responses of Alzheimer's Disease. Biomedicines 2023; 11:3232. [PMID: 38137453 PMCID: PMC10741223 DOI: 10.3390/biomedicines11123232] [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: 10/25/2023] [Revised: 12/01/2023] [Accepted: 12/03/2023] [Indexed: 12/24/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by progressive accumulations of extracellular amyloid-beta (Aβ) aggregates from soluble oligomers to insoluble plaques and hyperphosphorylated intraneuronal tau, also from soluble oligomers to insoluble neurofibrillary tangles (NFTs). Tau and Aβ complexes spread from the entorhinal cortex of the brain to interconnected regions, where they bind pattern recognition receptors on microglia and astroglia to trigger inflammation and neurotoxicity that ultimately lead to neurodegeneration and clinical AD. Systemic inflammation is initiated by Aβ's egress into the circulation, which may be secondary to microglial activation and can confer both destructive and reparative actions. Microglial activation pathways and downstream drivers of Aβ/NFT neurotoxicity, including inflammatory regulators, are primary targets for AD therapy. Osteopontin (OPN), an inflammatory cytokine and biomarker of AD, is implicated in Aβ clearance and toxicity, microglial activation, and inflammation, and is considered to be a potential therapeutic target. Here, using the most relevant works from the literature, we review and contextualize the evidence for a central role of OPN and associated inflammation in AD.
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Affiliation(s)
- Roshni C. Lalwani
- Interdisciplinary Stem Cell Institute, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA;
| | - Claude-Henry Volmar
- Department of Psychiatry, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (C.-H.V.); (C.W.)
- Center for Therapeutic Innovation, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Claes Wahlestedt
- Department of Psychiatry, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (C.-H.V.); (C.W.)
- Center for Therapeutic Innovation, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Keith A. Webster
- Integene International Holdings, LLC, Miami, FL 33137, USA;
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
- Everglades BioPharma, Houston, TX 77098, USA
| | - Lina A. Shehadeh
- Interdisciplinary Stem Cell Institute, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA;
- Department of Medicine, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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Huat TJ, Onraet T, Camats-Perna J, Newcombe EA, Ngo KC, Sue AN, Mirzaei M, LaFerla FM, Medeiros R. Deletion of MyD88 in astrocytes prevents β-amyloid-induced neuropathology in mice. Glia 2023; 71:431-449. [PMID: 36271704 PMCID: PMC9970273 DOI: 10.1002/glia.24285] [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: 05/18/2022] [Revised: 10/04/2022] [Accepted: 10/07/2022] [Indexed: 11/07/2022]
Abstract
As the understanding of immune responses in Alzheimer's disease (AD) is in its early phases, there remains an urgency to identify the cellular and molecular processes driving chronic inflammation. In AD, a subpopulation of astrocytes acquires a neurotoxic phenotype which prompts them to lose typical physiological features. While the underlying molecular mechanisms are still unknown, evidence suggests that myeloid differentiation primary response 88 (MyD88) adaptor protein may play a role in coordinating these cells' immune responses in AD. Herein, we combined studies in human postmortem samples with a conditional genetic knockout mouse model to investigate the link between MyD88 and astrocytes in AD. In silico analyses of bulk and cell-specific transcriptomic data from human postmortem brains demonstrated an upregulation of MyD88 expression in astrocytes in AD versus non-AD individuals. Proteomic studies revealed an increase in glial fibrillary acidic protein in multiple brain regions of AD subjects. These studies also showed that although overall MyD88 steady-state levels were unaffected by AD, this protein was enriched in astrocytes near amyloid plaques and neurofibrillary tangles. Functional studies in mice indicated that the deletion of astrocytic MyD88 protected animals from the acute synaptic toxicity and cognitive impairment caused by the intracerebroventricular administration of β-amyloid (Aβ). Lastly, unbiased proteomic analysis revealed that loss of astrocytic MyD88 resulted in altered astrocyte reactivity, lower levels of immune-related proteins, and higher expression of synaptic-related proteins in response to Aβ. Our studies provide evidence of the pivotal role played by MyD88 in the regulation of astrocytes response to AD.
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Affiliation(s)
- Tee Jong Huat
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland. Brisbane, QLD, Australia
- Centre for Stem Cell Ageing and Regenerative Engineering, The University of Queensland. Brisbane, QLD, Australia
| | - Tessa Onraet
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland. Brisbane, QLD, Australia
| | - Judith Camats-Perna
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland. Brisbane, QLD, Australia
| | - Estella A. Newcombe
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland. Brisbane, QLD, Australia
| | - Kim C. Ngo
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine. Irvine, CA, USA
| | - Ashley N. Sue
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine. Irvine, CA, USA
| | - Mehdi Mirzaei
- Clinical Medicine Department, Faculty of Medicine, Health and Human Sciences, Macquarie University. Sydney, NSW, Australia
| | - Frank M. LaFerla
- Department of Neurobiology and Behavior, University of California, Irvine. Irvine, CA, USA
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine. Irvine, CA, USA
| | - Rodrigo Medeiros
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland. Brisbane, QLD, Australia
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine. Irvine, CA, USA
- Correspondence: Rodrigo Medeiros, University of California, Irvine, 3400A Biological Sciences III, Irvine, CA 92697-4545.
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Luo Q, Schnöder L, Hao W, Litzenburger K, Decker Y, Tomic I, Menger MD, Liu Y, Fassbender K. p38α‐MAPK‐deficient myeloid cells ameliorate symptoms and pathology of
APP
‐transgenic Alzheimer's disease mice. Aging Cell 2022; 21:e13679. [PMID: 35909315 PMCID: PMC9381888 DOI: 10.1111/acel.13679] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 06/26/2022] [Accepted: 07/07/2022] [Indexed: 11/27/2022] Open
Abstract
Alzheimer's disease (AD), the most common cause of dementia in the elderly, is pathologically characterized by extracellular deposition of amyloid‐β peptides (Aβ) and microglia‐dominated inflammatory activation in the brain. p38α‐MAPK is activated in both neurons and microglia. How p38α‐MAPK in microglia contributes to AD pathogenesis remains unclear. In this study, we conditionally knocked out p38α‐MAPK in all myeloid cells or specifically in microglia of APP‐transgenic mice, and examined animals for AD‐associated pathologies (i.e., cognitive deficits, Aβ pathology, and neuroinflammation) and individual microglia for their inflammatory activation and Aβ internalization at different disease stages (e.g., at 4 and 9 months of age). Our experiments showed that p38α‐MAPK‐deficient myeloid cells were more effective than p38α‐MAPK‐deficient microglia in reducing cerebral Aβ and neuronal impairment in APP‐transgenic mice. Deficiency of p38α‐MAPK in myeloid cells inhibited inflammatory activation of individual microglia at 4 months but enhanced it at 9 months. Inflammatory activation promoted microglial internalization of Aβ. Interestingly, p38α‐MAPK‐deficient myeloid cells reduced IL‐17a‐expressing CD4‐positive lymphocytes in 9 but not 4‐month‐old APP‐transgenic mice. By cross‐breeding APP‐transgenic mice with Il‐17a‐knockout mice, we observed that IL‐17a deficiency potentially activated microglia and reduced Aβ deposition in the brain as shown in 9‐month‐old myeloid p38α‐MAPK‐deficient AD mice. Thus, p38α‐MAPK deficiency in all myeloid cells, but not only in microglia, prevents AD progression. IL‐17a‐expressing lymphocytes may partially mediate the pathogenic role of p38α‐MAPK in peripheral myeloid cells. Our study supports p38α‐MAPK as a therapeutic target for AD patients.
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Affiliation(s)
- Qinghua Luo
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Laura Schnöder
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Wenlin Hao
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Kathrin Litzenburger
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Yann Decker
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Inge Tomic
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Michael D. Menger
- Institute for Clinical and Experimental Surgery Saarland University Homburg Germany
| | - Yang Liu
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
| | - Klaus Fassbender
- Department of Neurology Saarland University Homburg Germany
- German Institute for Dementia Prevention (DIDP) Saarland University Homburg Germany
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Cucos CA, Dobre M, Dragnea EM, Manda G, Milanesi E. Increased MYD88 blood transcript in a mouse model of Alzheimer’s disease. BMC Neurosci 2022; 23:13. [PMID: 35277123 PMCID: PMC8917693 DOI: 10.1186/s12868-022-00699-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 02/28/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Neuroinflammation plays a prominent role in Alzheimer’s disease (AD), both in pathogenesis and disease progression. It has been shown that TLR/MYD88 signaling is involved in the chronic low-grade sterile inflammation associated with AD. Several studies have evidenced high levels of MYD88 in the brain of patients and animal models of AD, but no study has assessed so far its levels in blood.
Methods
In this study we evaluated the blood mRNA levels of MYD88 in a mouse model of AD, and also the putative effect of Rivastigmine treatment on MYD88 expression. Twenty-eight transgenic APP/TAU mice (AT) and twenty-two control C57/BL6j mice (WT) were included in this study, out of which five transgenic AT and five WT mice were treated with Rivastigmine.
Results
Increased MYD88 transcript in the whole blood from AT mice as compared to WT controls was found, which seems to increase in time due to disease progression and not to aging. This finding suggests that blood leukocytes are primed to develop TLR/MYD-mediated inflammatory processes. Moreover, results indicate that MYD88 blood levels were not modulated by the diseases-specific treatment with Rivastigmine.
Conclusions
Our results suggest that MYD88 might be a promising blood biomarker to monitor AD progression.
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